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Predictive power control of an AC/DC/AC converter
Abstract
This paper presents a new control scheme for a regenerative AC/DC/AC converter using model based predictive control. The control strategy minimizes quality functions, which represent the desired behavior of the converter. At the inverter side, the load current error is minimized, while at the input side, the active and reactive powers are controlled directly. The main advantages of this method are: no need of linear current controllers, coordinates transformations or modulators for converter and inverter. The rectifier operates with sinusoidal input currents and unity power factor, while sinusoidal currents are generated out at the inverter load.
... With the development of powerful and fast microprocessors, increasing attention has been dedicated to predictive current control. In this method, load and converter models are used to predict current behaviour, and thereby select the most appropriate actuation following arbitrary control criteria [11]. Predictive control is a very wide concept and different control methods have been presented under this name. ...
... This property was exploited in an earlier study [12], where predictive control was used to minimize switching frequency for high-power inverters. Also in [11], this property of predictive control is used to evaluate the behaviour of the current error for each switching state in a single-phase active filter. ...
... Shifting the discrete time one step forward, i(k+1)=[L*i(k)+Ts*v(k+1)] / (R*TS+L) (11) In the proposed predictive algorithm, load current is evaluated for each of the possible seven voltage vectors, giving seven different current predictions. The voltage vector whose current prediction is closest to the expected current reference is applied to the load at the next sampling instant. ...
... A linearized system model can be constructed by inserting the system model into the linearization formula (17). For the given back-to-back system, the gradients ∂f ∂x and ∂f ∂u are given as: ...
... Applying (20) to (17) yields the well-known linear system model:ẋ ...
... As depicted in Figure 1, a centralized control approach, consisting of a predictive current control [16] to control the load side, and a predictive power control [17] to control the grid side, is utilised in this study. This control approach is summarized in figure 2. The controller is defined in three steps: first, the reference output y ref (t) is defined. ...
In this paper, a novel control method for back-toback converters used in grid-to-motor connections is explored. To increase the robustness of low DC-link capacitances, a control method based on variable switching point model predictive control is proposed. While previous model predictive control methods for the back-to-back converter selected a certain switching state to fulfill all control goals, we use the switching time in addition to the switching state in order to minimise deviations from the target voltage. Choosing a variable switching point provides an additional degree of freedom to the control framework and allows the system to cope with the large number of control variables. In this case, the variable switching point is used to minimize the effects of low DC-link capacitances on the system. This can either be achieved by selecting a switching point that yields low DClink capacitor charging or by selecting a switching point that aims to keep the DC-link voltage close to the reference. The proposed method is verified through numerical simulations and hardware-in-the-loop (HIL) experiments and compared to existing approaches. The results show that it is possible to control the DClink using only the switching point of the converter.
... However, a PI controller is used to determine the reference power based on DC link voltage variation which leads to slower dynamics. Also, in [24], a PI controller is used to regulate the DC link voltage and determine the reference power for MPC controller. In addition to slower dynamic response, in both [23] and [24] it is the load's current that is controlled, not the load's voltage. ...
... Also, in [24], a PI controller is used to regulate the DC link voltage and determine the reference power for MPC controller. In addition to slower dynamic response, in both [23] and [24] it is the load's current that is controlled, not the load's voltage. ...
... Measure: v f , i c , i L Calculate: Eq. (23), (24) g opt,inv = ∞ for j = 1 : Number of states do Eq. (25), (26) Cost Function Calculation: ...
... The load current dynamics can be presented by the following equation [11] = + + ...
... The grid voltage is assumed to be sinusoidal and having constant amplitude and constant frequency for the simplification of the simulation. The load current for the balanced three phase circuit can be defined as [11] ...
... Using this equation into Eqn. 4, the future load currents can be estimated as [11] ( + 1) = (1 − ) ( ) + ( ( + 1) − ( + 1)) (8) where, ( +1) is the grid voltage at time ( +1) i.e. the next time step. This grid voltage can be estimated using the measured voltage and current through the following equation [11]. ...
Maximum penetration of produced photovoltaic (PV) power to the grid is very important for modern power system. However, some power is dissipated in the dc/ac converter due to the improper control strategy. It makes the grid connected PV systems inefficient. Therefore, model predictive control (MPC) based energy efficient conversion of PV power is proposed in this paper. MPC selects an optimal control action in every sampling instant for the dc/ac converter by minimizing a predefined cost function. Hence, the controller yields lower current total harmonic distortion (THD) than the traditional pulse width modulation strategy, and thus lower loss in the semiconductor devices. As a result, more power can be penetrated to the ac grid corresponding to a specified PV system. Simulation results in terms of current tracking accuracy, current THD and load flow analysis are presented in order to show the effectiveness of the controller. Index Terms-Model predictive control, dc/ac conversion, total harmonic distortion, load flow analysis.
... Ce problème est traité dans [10][11][12][13][14][15][16], où les auteurs proposent des méthodes pour limiter les variations ou pour régler la fréquence de commutation. Dans [17][18][19][20][21][22][23][24][25][26][27], les méthodes de contrôle direct de la puissance et de placement vectoriel des commandes sont étudiées. Nous pouvons noter que la plupart de ces travaux ont été réalisés sur des convertisseurs DC-AC ou AC multicellulaires, mais le problème des convertisseurs DC-DC multicellulaires entrelacés couplés n'a pas été traité de manière significative. ...
... It has a straight relation with the switching frequency of the power converter. The control of switching frequency is a main issue when using FCS-MPC and many authors propose methods for this purpose [7]- [13] [14][15][16][17][18][19][20]. ...
... -First the = 6 eigen values in order to settle the overall closed loop dynamics. Writing the characteristic equation and identifying it with its desire form leads to = 6 non-linear equations as in equation (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). ...
The interleaved multicell DC-DC power converters are broadly used in many applications and systems especially in renewable energy systems and microgrids. They reduce the current ripple at the input and output side. Also, an implemented magnetic coupling between cells leads to reduce the current ripple in each of them and to improve the dynamical electrical behavior. These properties involve a reduction on the filtering requirements and so, allow to improve the converter compactness as well as its conversion efficiency. Nevertheless, for such power converters, the control complexity is also increased as well as the number of required sensors.The thesis aims to establish different mode of control of interleaved multicell DC-DC converters. The common point of these methods is to control the external quantities at the output of the converter but also the internal quantities, constituted by the circulating currents between parallel cells or in other words the differential currents. Three main strategies are investigated: the first one uses classical linear controllers with different decoupling technics and focuses on the robustness regarding the system parameters variations. The second one uses a Model Predictive Control technic which is designed to provide a fix switching frequency and interleaving of the cells PWM commands. The last one presents a space vector direct control of the differential currents.In a last part, these control principles are tested on a prototype and implemented on a Microcontroller and FPGA board in order to carry out an experimental verification.
... 4. The practical limitation of power converters, such as switching frequency, ripple reduction, neutral point balanced, can be included easily by adding constrained conditions to the synthesis conditions. 5. Most importantly, all the design is done off-line which can highly release the computation burden. ...
... For simplicity of explanation, in the following part, the different control methods are introduced based a typical buck converter. 5 6 ...
... Only the first control policy is implemented, and then the same prediction procedure repeats every sampling period. Due to the high amount of calculations for the online implementation, model predictive control has few applications in power converter control [113,114,115,116,5]. ...
Switched-mode power converters are some of the most widely used power electronics circuits due to their advantages of high conversion efficiency, flexible output voltage, light weight. A variety of control methods have been developed for the switched-mode power converters. However, in many practical situation, additional constraints need to be considered, e.g., safety measurement, current limiting or soft-starting, gross changes of operation point with guaranteed system stability, which has not been fully addressed in the available research works. On the other hand, the majority of the control design for power converters are based on the state-space averaged approach which involves considerable approximation in analysis and synthesis. Hence, advanced control techniques are in demand, which should be more constraints friendly and based on more precise models.
In this thesis, much attention has been spent on designing controllers for both DC-DC converters and DC-AC inverters based on hybrid modelling and Lyapunov stability theory. Due to the existence of the power switches, switched-mode power converters are hybrid systems with both continuous dynamics and discrete transition events. Instead of linearizing the converter model around a specific operating point, hybrid modelling captures both dynamics, which results in more accurate models.
Firstly, a novel sampled-data control approach is proposed for DC-DC converters. DC-DC converters are modeled as sampled-data switched affine systems according to the status of the power switch. In order to avoid the delay of the switching signal, an on-line prediction method is adopted to estimate the system state at the next switching instant. Based on the switched affine model and the predicted system state, a novel switching control algorithm is synthesized by using the switched Lyapunov theory. The proposed approach is able to not only drive the output to a prescribed set point from any initial condition, but also track a varying reference signal, and the switching frequency can be adjusted online with guaranteed stability. In addition, with this approach, Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM) operations can be treated in a unified way. Experimental verification has been carried out to test the effectiveness and merits of the proposed method.
Furthermore, to compensate the information loss due to limited access to the state, a multiple sampling scheme is employed to derive a discrete-time switched affine model with an augmented measurement output for DC-DC converters. Based on the model, an output-feedback switching control law, which drives the system state to a set of attainable switched equilibria, is synthesized by using a quadratic state-space partition. The multiple sampling scheme not only facilitates the controller synthesis, but also improves the energy efficiency of the converter by allowing a lower switching frequency.
In addition, hybrid modelling techniques have been extended to more complicated cases – DC-AC inverters as the increasing number of power switches and the time-variant nature of the references. A current controller based on the hybrid model of the three-phase two-level inverter has been developed, which can drive the inverter currents tracking the desired power references in realtime and keep a unity power factor at the same time. This method has been extended to three-phase NPC inverters later on. However, in order to solve the neutral point balancing issue, a capacitor voltages prediction algorithm, modified from model predictive control, has been adopted. It should also be mentioned that a novel hybrid model for a grid-connected single-phase NPC inverter also has been presented, which models not only the dynamic of the inverter but also the dynamic of the current reference. An experimental test platform including a three-phase NPC inverter and a FPGA control board has been designed to demonstrate the implementation of the proposed control scheme in practice.
... In [16], a nonlinear controller that uses a new complex state-space modeling method is proposed and verified against a grid-tied AFE. In [17], the dclink control is fulfilled by using a proportional-integration (PI) controller, which generates the reference for grid-side inner predictive power controller. For steady state, the dc-link voltage and grid-side active power are controlled nicely. ...
... Generation/Extrapolation a) System states prediction: For a PI-DMPC scheme (see, e.g., [17]), the system states that are necessary to predict are load-side currents i pαβ l [k + 1], grid-side active power P p n [k + 1], and reactive power Q p n [k + 1], which are given by (9)-(11), respectively. ...
... The cost function for the grid side is designed as (9)-(12), respectively. b) Reference generation/extrapolation: The same method for the load-side current and grid-side reactive power reference generation used in PI-DMPC scheme is again adopted for QC-DMPC [see (17)]. The dc-link voltage reference V * dc [k + 1] and grid-side active power reference P * n [k + 1] are obtained here using a dynamic reference generation concept and load-side power estimation. ...
... gives a sufficiently accurate approximation of time-continuous models (see, e.g., [8] and [29]). If the sampling interval is large (larger than hundreds of microseconds in the considered application), Euler discretization in (30) may not meet the required approximation accuracy, and then, more sophisticated discretization methods (like Runge-Kutta or linear multistage) should be considered. ...
... which must then be modulated by the SVM. The future loadside reference value is obtained by applying a second-order extrapolation algorithm (see [29] for more information) ...
... In this paper, all the algorithms [e.g., (25), (29), (33), (34), (48), and (49)] are divided into small subroutines and are implemented using the single-cycle timed loop (SCTL) structure. The FPGA top level clock is set to 40 MHz. ...
... Por otro lado, en Rodríguez et al. (2005) presenta un sistema de control predictivo de potencia de un convertidor AC/DC/AC sobre cada una de las etapas del convertidor, enfocándose principalmente en los requerimientos de corriente y potencia en la carga. Previo al control de corriente, para asegurar una tensión constante hacia el inversor, se controla el voltaje DC del capacitor, manteniéndolo de manera continua y en un rango de referencia que asegure el correcto funcionamiento del control de corriente en la carga. ...
... rectifier, AFEs), ya que permite un flujo bidireccional de potencia, mediante Control Directo de Potencia (Direct Power Control, DPC), donde las potencias activa y reactiva son estimadas usando las medidas de corriente muestreadas para la carga; y el voltaje en la etapa DC es regulado controlando las corrientes de entrada o la entrada de potencia (Rodríguez et. al. 2005). La función de calidad evalúa el error de la entrada de potencia activa y reactiva para el rectificador. Para efectos de cálculos y deducción del sistema de control predictivo, conviene representar el generador como una fuente trifásica con impedancia externa. Donde L s y R s corresponde a la inductancia y resistencia equivalente del ge ...
... Para efectos de cálculos y deducción del sistema de control predictivo, conviene representar el generador como una fuente trifásica con impedancia externa. Donde L s y R s corresponde a la inductancia y resistencia equivalente del generador respectivamente, i s el vector de corriente del generador, v s es el voltaje del generador, v afe es el voltaje generado por el rectificador, V dc el voltaje en el capacitor (Rodríguez et al., 2005). Donde v inv es el voltaje generado por el inversor e i l es la corriente de carga. ...
Resumen La preocupante situación medioambiental a nivel global y la constante innovación han permitido el mejoramiento de la eficiencia energética de los sistemas eólicos debido al avance en el tamaño de los generadores y al desarrollo de la electrónica de potencia para su extracción. Contribuyendo al mejoramiento, este articulo presenta un sistema de control predictivo en la etapa de conversión de potencia que regule los requerimientos de potencia eléctrica del sistema según la carga presente. El controlador predictivo se enfoca para un convertidor AC/DC/AC aplicado a un sistema aerogenerador con acople directo, particularmente a los requerimientos de potencia y corriente de la carga. Vía simulación se comprueba su funcionamiento y se compara con una topología de conversión usada para sistemas convencionales. Se analiza el sistema simulado bajo características de viento medidas en la zona sur. Además, se consideran fallas en el enlace DC y en la carga, para el análisis de robustez. De los resultados se observa como el sistema controlado mantiene valores de voltaje y corriente requeridos por la carga frente a variaciones de viento, y también se muestra que el sistema controlado tiene un buen desempeño ante ocurrencia de fallas eléctricas. Abstract The constant innovation and improvement of non-conventional energy sources, have made wind power is a competitive energy source, so the investigation has made rapid progress in the size of wind turbines and developing the associated power electronics more efficient. From the standpoint of energy efficiency, this paper develops a predictive control system in the power conversion in order to regulate the electric power requirements of the system according to the present load. The development of predictive control is performed to the AC/DC/AC converter applied to a wind turbine system with direct coupling. Via simulation tests the performance of this driver and compared with a conversion topology used for
... 3) Using predictive direct power control (P-DPC). Rodriguez et al. proposed a new strategy that eliminates the hysteresis controllers and switching table [16], [17]. In the proposed control strategy, the effects of each switching state on the input power are evaluated, and the switching state that minimizes a quality function is selected and applied during the next sampling period. ...
... When k is set to 24, the values of f ξ and f μ are integers between -24 and +24. According to (16), (23) and (24), the approximate proportional relationship between f ξ , f μ and the change rates of the active and reactive power can be expressed as: ...
... To obtain the values of f ξ and f μ in the tables, the following steps should be followed. For example, if the value of f ξ of vector u 16 when n θ =7 is to be found, the specific steps are presented as follows: ...
This paper proposes a novel direct power control (DPC) strategy for neutral-point-clamped (NPC) three-level rectifiers, to directly control the active power, the reactive power and the neutral point potential of the rectifiers by referring to three pre-calculated vector influence tables and minimizing an objective function. In the three vector influence tables, the influences of different voltage vectors on the active power, the reactive power and the neutral-point potential are shown explicitly. A conceptual description and control algorithm of the proposed controller are presented in this paper. Then, numerical simulations and experiments are carried out to validate the proposed method. Both the simulation and experimental results show that good performances during both the steady-state and transient operating conditions are achieved. As a result, the proposed strategy has been proven to be effective for NPC three-level rectifiers.
... In [16], a nonlinear controller that uses a new complex state-space modeling method is proposed and verified against a grid-tied AFE. In [17], the dclink control is fulfilled by using a proportional-integration (PI) controller, which generates the reference for grid-side inner predictive power controller. For steady state, the dc-link voltage and grid-side active power are controlled nicely. ...
... Generation/Extrapolation a) System states prediction: For a PI-DMPC scheme (see, e.g., [17]), the system states that are necessary to predict are load-side currents i pαβ l [k + 1], grid-side active power P p n [k + 1], and reactive power Q p n [k + 1], which are given by (9)-(11), respectively. ...
... The cost function for the grid side is designed as (9)-(12), respectively. b) Reference generation/extrapolation: The same method for the load-side current and grid-side reactive power reference generation used in PI-DMPC scheme is again adopted for QC-DMPC [see (17)]. The dc-link voltage reference V * dc [k + 1] and grid-side active power reference P * n [k + 1] are obtained here using a dynamic reference generation concept and load-side power estimation. ...
Voltage source back-to-back power converters are widely used in grid-tied applications. This paper presents a quasi-centralized direct model predictive control (QC-DMPC) scheme for back-to-back converter control without a dc-link outer-loop controller. Furthermore, the QC-DMPC is experimentally compared with a conventional proportional-integration (PI) dc-link controller-based DMPC (PI-DMPC) scheme. For the QC-DMPC scheme, the dc-link voltage is directly controlled by a grid-side predictive controller using a dynamic reference generation concept and load-side power estimation. For the PI-DMPC scheme, the dc-link voltage is controlled by an external PI controller. Both schemes are implemented on a field programmable gate array (FPGA)-based platform. Effectiveness of the proposed QC-DMPC is verified by both simulation and experimental data. Moreover, FPGA implementation issues (resource usage and timing information), dc-link control performance, and robustness to parameter variation of the two DMPC schemes are compared in detail. The results emphasize that the QC-DMPC may outperform the PI-DMPC scheme in normal operation but with a slightly higher usage of FPGA resources. However, PI-DMPC scheme is more robust when parameter variations are considered.
... gives a sufficiently accurate approximation of time-continuous models (see e.g. [8], [29]). If the sampling interval is large (larger than hundreds of µs in the considered application), Euler discretization in (30) may not meet the required approximation accuracy, then more sophisticated discretization methods (like Runge-Kutta or linear multistage) should be considered. ...
... which must then be modulated by the SVM. The future load side reference value is obtained by applying a second-order extrapolation algorithm (see [29] for more information): ...
... In this work, all the algorithms (e.g. (25), (29), (33), (34), (48) and (49)) are divided into small sub-routines and are implemented using the Single-Cycle-Timed-Loop (SCTL) structure. The FPGA top level clock is set to 40 MHz. ...
This work proposes and experimentally verifies
a Constant-Switching-Frequency Model Predictive Controller
(CSF-MPC) with Space Vector Modulator (SVM) and a novel
Virtual Flux (VF) estimation method for a back-to-back voltage
source power converter. The novelty of the proposed method is
the development of a time domain Initial Bias Compensation
Virtual Flux (IBC-VF) estimation method and its combination
with a constant-switching-frequency model predictive control
scheme. Theoretical analysis and implementation procedures
of the proposed method are developed in detail. With the
proposed IBC-VF method, the net side voltage and power can be
accurately estimated from the second sampling interval (200µs)
on. The whole IBC-VF based CSF-MPC scheme is realized in the
αβ frame and, so, does not require Park’s transformation. The
proposed control scheme is implemented on a commercial off-
the-shelf FPGA based platform. By using a Single-Cycle-Timed-
Loop (SCTL) technique, the whole calculation is finished within
2.6µs, making a calculation-time compensation obsolete. Both
simulation and experimental results emphasize the effectiveness
of the proposed scheme.
... However, most MPCs in literature, including the references above, are adopted as an inner loop of the outer PI controller, which constructs the conventional PI controller-based model predictive control (PI-MPC). A DC-link voltage PI controller is always necessary to generate reference for MPC to control the back-to-back converter with PI-MPC [24]. This is a typical cascaded control structure because MPC is nesting inside the external voltage PI control loop [25], [26]. ...
... Citation information: DOI 10.1109/TPEL.2024.3350897 [24], [28]. The control structure is cascaded, as the inner MPC is nesting inside the outer voltage PI control loop. ...
In this paper, a cascade-free model predictive control scheme without the outer DC-link voltage control loop is proposed for the back-to-back converter-fed permanent magnet synchronous machine (PMSM) drive system. Specifically, the voltage regulation term is integrated together with the power regulation term into a newlyconstructed cost function so that the control of DC-link voltage as well as power can be realized by a single cost function. To predict accurately and to reduce the sensitivity to variable parameters, the expressions of DC-link voltage and power are dynamically corrected, thus enhancing the robustness. In addition to presenting no tracking deviation in steady state, the DC-link voltage also presents smaller deviation from reference and faster recovery time in dynamics. It is beneficial to enhancing the reliability of system since the voltage surge on power switches and diodes has been reduced. Besides, controllable power flow, sinusoidal phase current, and well-regulated electromagnetic torque can be achieved in the system as well. A series of experiments are carried out to test the feasibility of the proposed scheme. Performance comparisons with the classical proportional integration controller-based model predictive control (PI-MPC) and the modified cascade-free quasi-centralized model predictive control (QC-MPC) validate the improvements of the proposed control scheme
... However, most MPCs in literature are generally developed as an inner controller to cooperate with the outer PI controller, thereby forming the conventional PI controller-based MPC (PI-MPC). It is a cascaded structure since the inner MPC is nested within the outer PI control loop [18]. To further improve the dynamic response, a cascade-free algorithm without the outer speed PI controller is developed in [19]. ...
... MPC is generally adopted as the inner controller to track the active power setpoint P * g and reactive power setpoint Q * g in GC, and the cost function in conventional PI-MPC strategy is defined as [18] ...
In this paper, a direct predictive voltage control (DPVC) is proposed for the grid-connected permanent magnet synchronous generator (PMSG) system. In the proposed strategy, the dc-link voltage regulation and power regulation terms are merged into one cost function, thereby eliminating the conventional cascade control structure. The strategy selects the voltage vector that not only will generate a dc-link voltage closer to the setpoint at instant
$k+2$
, but will generate an active power that can further reduce that voltage error for the future instant. To cope with the mismatch between the actual and nominal parameters, Kalman filter has been added to compensate for the steady-state error. Besides, to enhance the dynamic performance and to save the effort of parameter tuning, the weighting factor is further eliminated from the cost function by sorting the terms into two groups and independently evaluating each group in turn. To fully validate the effectiveness of the proposed strategy, the experimental test waveforms of the DPVC strategy with and without weighting factor have been presented and compared with that of the conventional PI-MPC strategy in various testing conditions.
... Predictive Power Control (PPC) is an MPC technique that aims to control both, the active as well as the reactive power which is flowing into the system. It has been introduced for the back-to-back converter in [5]. Based on PPC, several more advanced model predictive control methods have been proposed in [6]. ...
... One example of a popular nonlinear system in power electronics is the Three-level neutral point clamped (NPC) backto-back PMSG wind turbine system [6]. The Three-level NPC back-to-back PMSG system is a promising technology in the field of renewable energy applications [5]- [7], [12]. A detailed description of the system is given in [12]. ...
This paper investigates the combination of twomodel predictive control concepts, sequential model predictivecontrol and long-horizon model predictive control for powerelectronics. To achieve sequential model predictive control, theoptimization problem is split into two subproblems: The first onesummarizes all control goals which linearly depend on the systeminputs. Sequential model predictive control generally requires toobtain more than one solution for the first subproblem. Due tothe mixed-integer nature of finite control set model predictivecontrol power electronics a special sphere decoder is thereforeproposed within the paper. The second subproblem consists ofall those control goals which depend nonlinearly on the systeminputs and is solved by an exhaustive search. The effectivenessof the proposed method is validated via numerical simulationsat different scenarios on a three-level neutral point clampedpermanent magnet synchronous generator wind turbine systemand compared to other long-horizon model predictive controlmethods.
... Predictive Power Control (PPC) is an MPC technique that aims to control both, the active as well as the reactive power which is flowing into the system. It has been introduced for the back-to-back converter in [5]. Based on PPC, several more advanced model predictive control methods have been proposed in [6]. ...
... One example of a popular nonlinear system in power electronics is the Three-level neutral point clamped (NPC) backto-back PMSG wind turbine system [6]. The Three-level NPC back-to-back PMSG system is a promising technology in the field of renewable energy applications [5]- [7], [12]. A detailed description of the system is given in [12]. ...
This paper investigates the combination of two model predictive control concepts, sequential model predictive control and long-horizon model predictive control for power electronics. To achieve sequential model predictive control, the optimization problem is split into two subproblems: The first one summarizes all control goals which linearly depend on the system inputs. Sequential model predictive control generally requires to obtain more than one solution for the first subproblem. Due to the mixed-integer nature of finite control set model predictive control power electronics a special sphere decoder is therefore proposed within the paper. The second subproblem consists of all those control goals which depend nonlinearly on the system inputs and is solved by an exhaustive search. The effectiveness of the proposed method is validated via numerical simulations at different scenarios on a three-level neutral point clamped permanent magnet synchronous generator wind turbine system and compared to otherlong-horizon model predictive control methods
... Also it is very popular due to fast transient response, increased control accuracy, low total harmonic distortion (THD), easy implementation and so on. Amongst the various predictive algorithms [9][10][11][12][13][14][15][16][17][18][19], the deadbeat predictive control uses the system model to track the reference in the next sampling period. It has found numerous applications in current control of inverters, rectifiers, active filters and so on. ...
... However, in this control the high sensitivity to grid voltage measurement causes grid current distortions. Further, the application of all these predictive control algorithms is preferably found in dc/ac, ac/dc and ac/dc/ac converters for motors controls [19][20][21][22][23]. Moreover, in [24,25] the application of predictive control to active filters is proposed. ...
This study aims to propose a control which is a combination of model predictive control (MPC) and hysteresis current control (HCC) referred as hysteresis-based predictive control. Similar to MPC, the system model is incorporated and used to determine predicted compensator currents without considering cost function. Further, these currents are compared with the reference currents extracted using instantaneous symmetrical component theory to generate switching for inverter. The control provides nearly constant switching frequency of neutral-point clamped (NPC) inverter in distributed static compensator applications. The method employs possible voltage vectors to obtain output current predictions. The zero tracking error is verified using validating condition (quality function) to ensure the proper current predictions. Further, by controlling the uncontrolled states and selecting maximum ON time with symmetrical switching sequence, nearly constant switching frequency is obtained. The performance of the proposed current control is compared with HCC and MPC and the remarkable improvement in terms of tracking; reduced current error bandwidth; reduced and constant switching frequency and load compensation are presented. Moreover, the theoretical and analytical comparisons are carried out to demonstrate the superiority of the proposed control. An extensive simulation and programming are carried out using MATLAB to extract the simulated results and validated through experimental studies.
... control of a two-level active-front end in [11], and further developed in [12]. In [13], a strategy which is based on duty cycle control is presented. ...
... This paper presents Model Predictive Direct Power Control (MPDPC), a new approach to the control of grid-connected converters, which regulates the instantaneous real and reactive power delivered to the grid within a set of symmetrical bounds, whilst minimising the device switching frequency of the converter. The use of a multi-step prediction horizon distinguishes MPDPC from the FCS-MPC-based strategies presented in [11] - [14]. The key benefit of MPDPC is the ability to achieve average device switching frequencies of well under 500 Hz whilst remaining within the acceptable limits of grid current harmonic distortion. ...
This paper presents a model predictive direct power control scheme for high-power grid-connected neutral-point-clamped converters. The controller regulates the instantaneous real and reactive powers, as well as the neutral-point potential of the converter, within a set of symmetrical bounds while, at the same time, minimizing the switching frequency of the converter. The proposed approach is distinct from previous predictive power control strategies in that a long prediction horizon is used, allowing lower device switching frequencies to be achieved. A detailed model of the system is provided, and the control algorithm is discussed. Simulation results validate the applicability of the controller to a 3-kV 6.72-MVA system. Experimental results, which are presented for a 240-V 1.68-kVA prototype, show good agreement with those obtained in simulation and further validate the concept.
... An optimized control action is then chosen to minimize a function that is based on a reference and predicted states, also known as a cost function. The use of MPC in power electronics began in the 1980s in low switching frequency applications since higher switching frequencies require more complex calculations due to the fact that cost function optimization requires a lot of computational effort, which was not available at that time [30,31,35,36]. It was only from the 1990s onwards that this technology had a leap of development due to the great technological advance of microprocessors capable of performing a large number of mathematical operations. ...
The multilevel back-to-back cascaded H-bridge converter (CHB-B2B) presents a significantly reduced components per level in comparison to other classical back-to-back multilevel topologies. However, this advantage cannot be fulfilled because of the several internal short circuits presented in the CHB-B2B when a conventional PWM modulation is applied. To solve this issue, a powerful math tool known as graph theory emerges as a solution for defining the converter switching matrix to be used with an appropriate control strategy, such as the model-based predictive control (MPC). Therefore, this research paper proposes a MPC with the graph theory approach applied to CHB-B2B which capable of not only eliminating the short circuit stages, but also exploring all the switching states remaining without losing the converter controllability and power quality. To demonstrate the proposed strategy applicability, the MPC with graph theory approach is tested in four different types of SST configurations, input-parallel output-parallel (IPOP), input-parallel output series (IPOS), input-series output-parallel (ISOP), and input-series output series (ISOS), attending distribution grids with different voltage and power levels. Real-time experimental results obtained in a hardware-in-the-loop (HIL) platform demonstrate the proposed strategy’s effectiveness, such as DC-link voltages regulation, multilevel voltage synthesis, and currents with reduced harmonic content.
... They often do not consider other connected power converters because they are made to control just one power converter. As a result, the control of (extensive) interconnected systems is typically dependent on local decentralized control schemes, with no information being exchanged between the power converters, as seen in [1], [15], [16], [17], [18], and [19]. Without changing the overall control strategy, decentralized MPC techniques can be simply scaled up by adding more power converters and establishing quick data exchange amongst the power converters. ...
This article proposes coordinated model predictive control (MPC) techniques for a DC-coupled hybrid microgrid system with solar photovoltaic and wind generated system. To achieve optimum power generation in the microgrid, the finite-control-set MPC (FCS-MPC) controls both PV-wind generated power using a DC-DC converter and a controlled rectifier. The mathematical formulation of the proposed hybrid microgrid system is described, and maximum power point tracking is employed to guarantee that the grid receives the maximum power. Furthermore, the 3-
$\Phi $
bidirectional two-level inverter is connected between the DC-bus and AC grid which is controlled by the grid side FCS-MPC controller. The FCS-MPC is used in all system control parts, eliminating the use of four proportional controllers (PI) and giving a better dynamic response. Additionally, the outcomes are evaluated in comparison to current techniques. The proposed power management technique is also based on the relationship between the overall demand and the produced power provided by both WDG and PV sources. Due to the unpredictability of the sources, several scenarios, including (i) Fixed radiation and fixed wind speed, (ii) Wind speed variation and constant radiation, and (iii) Changing solar radiation and steady wind speed, are considered to validate the performance of the proposed scheme. The findings are then discussed.
... Où T s est le temps de la période de commutation de la modulation vectorielle spatiale qui est la somme de tous les temps d'application des vecteurs utilisés pendant uneétape de calcul [107] : ...
Abstract
The use of multi-phase machines, which are destinated to achieve specific objectives related to the number of phases superior to three phasese,leads to a suitable control which essentially corresponds to the cost and simplicity of manipulation and requires a multi-phase power source produced by inverters of the same number of phases. The analysis of a five-phase inverter as well as the five phase load( preceeded by the analysis of three phase inveter mostly used in industry) are modulated in dq planes and simulated with MATLAB / SIMULINK.the calculation of the switching action can be delivered to the inverter is available in many methods. In this paper both the concept of neighbor vectors and the model predictive control are exploited for the calculation of the different switching. These two methods are compared to each other taking into account their effects on the output current. In addition the MPC controller is implemented for many values of the tuning parameter Lamda. Experimental simulation using MATLAB / SIMULINK confirms the influence of every method on the quality of the output current , i.e. the total harmonic distortion. the Simulink space, which is used, has advantages allowing the operator to manipulate the parameters in easy and fast way, and display the results.
Résumé
L'utilisation des machines polyphasés ,qui sont destinées à accomplir des taches speciales et relatives au nombre de phases superieur à trois, conduit à une commande appropriée qui correspond essentiellement au coût et à la simplicité de la manipulation et nécessite une source d'alimentation polyphasés produite par des convertisseurs du même nombre de phases. L'analyse d'un onduleur à cinq phases (précédé par l'étude de l'onduleur triphasé le plus utilisé dans l'industrie) ainsi que la charge à cinq phases sont modulées dans des plans dq et simulées avec MATLAB / SIMULINK. Le calcul de l'action de commutation peut être fourni à l'onduleur est disponible de nombreuses méthodes. Dans cette thèse, le concept des vecteurs voisins et le contrôle prédictif du modèle sont exploités pour le calcul des différentes commutations. Ces deux méthodes sont comparées en prenant en compte leurs effets sur le courant de sortie. De plus, le contrôleur MPC à base de modèle est implémenté pour de nombreuses valeurs du paramètre de réglage Lamda. Une simulation expérimentale utilisant MATLAB / SIMULINK confirme l’influence de chaque méthode sur la qualité du courant de sortie, c’est-à-dire la distorsion harmonique totale. L'espace Simulink utilisé présente des avantages permettant à l'opérateur de manipuler les paramètres de manière simple et rapide et d'afficher les résultats.
Mots clés : onduleur cinq phases, SVPWM, MPC
ملخص
يؤدي استخدام الآلات متعددة الاطوار ، والتي تهدف إلى تحقيق أهداف محددة تتعلق بعدد الاطوار التي تفوق ثلاث و التي لا تستطيع الالات ثلاثية الاطوار تحقيقها لنفس الكفاءة و المردود، إلى تحكم مناسب يتوافق بشكل أساسي مع تكلفة وبساطة المعالجة ويتطلب مصدر طاقة متعدد الاطوار يتم تحقيقه بواسطة مموجات من نفس عدد الاطوار.
ان دراسة و تحليل المموج خماسي الاطوار ) و التي تسبقها دراسة مماثلة للموج ثلاثي الاطوار ) و كذا الحمولة MATLAB / واجراء محاكاة لها في البرنامج ماتلاب dq المتصلة به بتضمينها في معلم ثنائي الابعاد .SIMULINK
إن حساب اوقات و اوامر غلق و فتح قاطعات الاستطاعة المشكلة للموج متاح باستعمال كثير من الطرق. التحكم التنبئي المبني على نموذج و تمت MPC في هذه الاطروحة ، تم التركيز على احدى الطرق المتقدمة تعتمد على مبدأ الاشعة المتجاورة. ان SVPWM مقارنته يطريقة اخرى واسعة الاستعمال و ذات كفاءة عالية مقارنة الطريقتين تعتمد اساسا على تاثير الطريقتين على جودة اشارة تيار الخروج المنتج. اضافة الى ذلك فات التركيز على الطريقة الاولى اخذ في الحسبان اجراء التجارب بقيم مختلفة لعوامل الترجيح.
ان النتائج لعملية المتحصل عليها اثبتت تاثير كل طريقة على جودة تيار الخروج ن خلال حساب التشويه التوافقي سمح بالتعامل مع مختلف العوامل MATLAB / SIMULINK الكلي. ان استعمال فضاء المحاكاة ماطلاب بسهولة و سرعة كبيرتين و اظهر النتائج بكل وضوح.
الكلمات المفتاحية: المموج خماسي الاطوار’ التحكم التنبئي المبني على نموذج’ تضمين عرض النبضة الشعاعي
... Où T s est le temps de la période de commutation de la modulation vectorielle spatiale qui est la somme de tous les temps d'application des vecteurs utilisés pendant uneétape de calcul [107] : ...
The use of multi-phase machines, which are destinated to achieve specific objectives related to the number of phases superior to three phases, leads to a suitable control which essentially corresponds to the cost and simplicity of manipulation and requires a multi-phase power source produced by inverters of the same number of phases. The analysis of a five-phase inverter as well as the five phase load( preceeded by the analysis of three phase inverter mostly used in industry) are modulated in dq planes and simulated with MATLAB / SIMULINK.the calculation of the switching action can be delivered to the inverter is available in many methods. In this paper both the concept of neighbor vectors and the model predictive control are exploited for the calculation of the different switching. These two methods are compared to each other taking into account their effects on the output current. In addition the MPC controller is implemented for many values of the tuning parameter Lambda. Experimental simulation using MATLAB / SIMULINK confirms the influence of every method on the quality of the output current , i.e. the total harmonic distortion. the Simulink space, which is used, has advantages allowing the operator to manipulate the parameters in easy and fast way, and display the results.
... M. Rossi Regarding the latter, several direct MPC-based strategies for the power control of a grid-tied two-level converter have been proposed in [4], [5], [6]. However, for MV applications the power electronic converter has to be operated at a low switching frequency because the switching losses typically dominate the conduction losses. ...
This paper presents a direct model predictive power control for a series-connected modular rectifier. The topology combines a diode rectifier and an active-front-end (AFE) converter to achieve a medium voltage target. A voltage control loop regulates the total dc voltage, providing the power references to the inner direct model predictive control. Operation under the desired real and reactive power is achieved, while minimizing the converter switching frequency. Moreover, successful operation and control of the AFE converter is guaranteed thanks to a hard constraint included in the optimization problem.
... We use predictive current control to control [10] the load side and predictive power control [11] to control the grid side. ...
In this paper, we propose a predictive control algorithm for back-to-back converters that is robust to low DC-link capacitance. To achieve this goal, an additional control objective, i.e., the charging of the DC-link capacitor within each sampling period, is included in the cost function to penalize the DC-link voltage ripple. In this way, a global optimized switching state is obtained and the good performances are illustrated with small DC-link capacitance in both transients and steady state. Simulation results confirm the effectiveness of the proposed method for both, high and low DC-link capacitance.
... where, represents the sampling period and the predictive load current for (K+1)th instant can be expressed as [14][15] ...
Designing a controller for a grid-connected inverter is a difficult task due to intermittent photovoltaic (PV) source which is connected to the input of the inverter. Inappropriate operation of the inverter produces high total harmonic distortion (THD) in the output current. This causes a significant amount of power loss and thus less power penetration to the grid. Hence, a predictive current control (PCC) based grid-connected inverter for penetrating more PV power to the ac grid is presented in this paper. The PCC selects an optimized switching signal based on a predefined cost function and thus provides a lower current THD. The existing controllers such as proportional-resonant and selective harmonic elimination are also simulated for the same parameters and compared to the proposed controller. To verify the effectiveness of the controller, the reference current of the controller is also varied in a wide range and tested for current THD. Simulation results show that the proposed PCC yields lower current THD than the existing controllers.
... Modification is done in this method so that it well fitted to drives and to all sinusoidal current and voltage waveforms are required is that of the rotating frame current regulator shown in figure1. The advantages of this control are satisfactory for drives of low and medium performance, Cinch and robust, unresponsive to load parameters and by increasing the switching frequency, performance of Linear control can be improved [6][7][8][9][10]. Delta modulation The fundamental diagram of a delta modulator current control is shown in figure 4. It is same as that of hysteresis control, but its operating principle is quite different. ...
In modern practice, voltage source inverter with current controllers is used in all applications to get faster response, good accuracy and high level performance. In this paper various methods of current controllers are discussed with three phase voltage source PWM converter. The first method includes PI current regulator, the second method comprises predictive current regulator with constant switching frequency, third method is hysteresis current controller and the fourth method fuzzy-logic based controllers are discussed.
... In the reference Chihab et al. (2015), various current control techniques applied to the PWM inverter are classified into two groups: linear current control (PI, PI-synchronous power, PI-rotary power, and state feedback), nonlinear current control (particle swarm optimization (PSO) based PI control, fuzzy logic control, and sliding mode, predictive power control) (Henrique et al. 2016;Dida and Benattous 2015;Pereira et al. 2016;Rodríguez et al. 2005). The reference Pichan et al. (2013) proposes a technique for controlling the current by fuzzy logic. ...
This paper presents experimental performance improvement of induction motor fed by five-leg AC–DC–AC converter with DC-link voltages offset compensation. In order to control the rectifier, a sliding mode control approach is proposed to track the DC-link voltage. The grid-side converter control is performed via a predictive power control, which minimizes the instantaneous input reactive power present in the system and compensates the undesirable harmonic contents of the grid current, under a unity power factor. In motor side, the inverter control is performed via a predictive torque control to achieve an accurate torque and flux references tracking with ripples reduction. The implementation of the proposed control architecture is achieved via a dSPACE 1104 card. The experimental results show that the proposed control strategy develops a faster active power response leading to low DC-link voltage variation, while the grid current is nearly sinusoidal with low total harmonic distortion. Experimental results reveal also that the drive system, associated with PTC technique, can effectively reduce flux and torque ripples with better dynamic and steady-state performance. Further, the proposed approaches minimize the average switching frequency.
... Other quality functions could evaluate the error integral over a sampling period, or the square error. Also, additional terms can be added to the quality function to improve other control aspects like minimising the switching frequency and DC link voltage balancing, as presented in [17], for a three-phase neutral point clamped inverter. ...
... Based on the analysis of the convention PI current control method above, this paper proposes a model predictive current control for 3TSMC. The FCS MPC is an attractive alternative to the classical control methods, due to its fast dynamic response, simple concept, and ability to include nonlinearities [5][6]. This technique has been successfully applied to a wide range of power converters, as reported in [7]-[ 1 1]. ...
This paper proposes a sample model predictive current control strategy for the third-harmonic injection two-stage matrix converter (3TSMC). The discrete-time model of 3TSMC is used to predict the future behavior for every feasible switching state. The control method chooses the optimal switching state that minimizes the cost functions, for rectifier and inverter. The model predictive current control consists of two parts. One is to produce sinusoidal three-phase input currents, and the other is to obtain high quality output currents. Besides, this control strategy guaranty good dynamic performance. Compared with the conventional PI current control method, the current quality has significantly improved by applying proposed approach. The feasibility of the proposed method is verified through simulation.
... gives a sufficiently accurate approximation of time-continuous models (see e.g. [20], [25]). ...
... In literature, it have been introduced several types of terms that can be included in a cost function and shows how these terms are related to different control design requirements for the system. Depending on the nature of the different terms involved in the formulation of the cost function, they can be classified in different groups, such as: cost function without weighting factor in which no need to set the weighting factor applied in [17,26,27] and [28]; cost function with weighting factor in the secondary term investigated in [29,30]; cost function with equally important terms proposed in [23]. Till the date in literature no analytical or numerical methods or control design theories to adjust the weighting factor for equally important term and currently they are evaluated with the iterative evaluation method [31]. ...
This paper proposes a weighting factor optimization method in predictive control algorithm for torque ripple reduction in an induction motor fed by an indirect matrix converter (IMC). In this paper, the torque ripple behavior is analyzed to validate the proposed weighting factor optimization method in the predictive control platform and shows the effectiveness of the system. Therefore, an optimization method is adopted here to calculate the optimum weighting factor corresponds to minimum torque ripple and is compared with the results of conventional weighting factor based predictive control algorithm. The predictive control algorithm selects the optimum switching state that minimizes a cost function based on optimized weighting factor to actuate the indirect matrix converter. The conventional and introduced weighting factor optimization method in predictive control algorithm are validated through simulations and experimental validation in DS1104 R&D controller platform and show the potential control, tracking of variables with their respective references and consequently reduces the torque ripple.
www.jeet.or.kr/LTKPSWeb/uploadfiles/be/201409/290920141542510941250.pdf
http://umexpert.um.edu.my/file/publication/00005361_115163.pdf
Model predictive control (MPC) concepts find an increasing application in the control of electronic power converters of different topologies. This is mainly due to the fast increase in computing power, e.g., by the application of system-on-chip architectures (FPGA $+$ DSP on a single chip). MPC strategies are usually developed for a single power converter. In many real applications, the power converters are coupled to other power converters, where decentralized MPC strategies do not yield optimal control performance. On the other hand, centralized MPC concepts that control the overall coupled converter system are not practically feasible due to the increase in computational demands. For this reason, this work studies the utilization of a data link between the power converters to use cooperative MPC strategies. In contrast to earlier works on this topic, it is investigated how a long prediction horizon of recently developed MPC concepts can be beneficially used for the control of coupled power converters. In particular, cooperative MPC strategies are proposed that use the predicted system behavior transferred by the other coupled converters. The benefits of these strategies will be demonstrated by comparison to a decentralized and a centralized MPC strategy. It will be shown that the proposed strategy also allows to reduce the size of certain system components as, e.g., the dc-link capacitor, which entails reduced costs and an increased system dynamics.
A direct speed control strategy based on finite control set model predictive control (FCS-MPC) with a voltage smoother is presented herein. In the proposed concept, a finite set of smoothed voltage vectors characterized by an adjustable amplitude and a movable origin is introduced as voltage candidates in the FCS-MPC scheme. The controller predicts the future current and speed and outputs the optimal smoothed voltage using pulse-width modulation. Owing to this control scheme, an abrupt change in the output voltage, which causes a large current ripple, is avoided without additional computational costs. Simulation and experimental results obtained using a permanent magnet synchronous motor fed by a two-level three-phase inverter show that the proposed method effectively reduces the current ripple while achieving a high dynamic drive compared with the conventional FCS-MPC scheme.
This paper addresses a controller for a full converter of variable-speed wind generators (VSWTs) composed of permanent magnet synchronous generators. Conventionally, several proportional-integral (PI) controllers and a phase lock loop (PLL) are used in the full converter for voltage-oriented control. The use of cascaded control loops with PI controllers degrades the control performance due to the wind-up of the integrators and complicates the tuning task. In this paper, we propose a new full converter control scheme based on predictive control and a single P-controller in the α-β stationary frame to replace the integrators and the PLL. The proposed controller can reduce the parameter tuning effort, is free from integrator wind-up and is robust to symmetrical and asymmetrical voltage dips. The effectiveness of the proposed method is verified through simulations.
Power electronic traction transformer (PETT) is a module-cascaded converter with high-frequency-link technology to realize high power conversion. A typical structure of PETT contains a single-phase cascaded H-bridge rectifier in the first stage and several dual active full-bridge DC-DC converters in the second stage. For PETT adopting such complex topological structure, the control strategy also becomes complicated and should be carefully designed. In this paper, a power-linked predictive control strategy for PETT is proposed based on the predictive controls of H-bridge rectifier and dual active full-bridge DC-DC converter. A power link is brought into the control strategy to connect H-bridge rectifier with DC-DC converter, through which the input power of PETT can match the output power. Moreover, the voltage balance control and power balance control are also combined with predictive control by power-linked predictive control strategy. Using such strategy, the fluctuation of H-bridge rectifier DC voltage is suppressed, the circumfluence among modules is reduced, and the dynamic and steady-state performances are both improved compared with traditional strategy. Simulation and experimentation platforms with both resistance load and motor load are built to show the effectiveness and correctness of power-linked predictive control strategy.
We present a novel model predictive control algorithm for three level neutral point clamped converter back-to-back PMSG wind turbine systems. In order to reduce the computational complexity we utilize a cascaded approach. The wind turbine as well as the grid outputs are optimized within the outer loop. In order to reduce the computational effort a modified sphere decoder is applied. The K best solution candidates of the outer loop are then passed on to the inner loop. The DC-link balance is optimized in the inner loop. Since the number of solution candidates is limited within the inner loop, an exhaustive search is applied. The framework is verified by means of numerical simulations.
This paper proposes a computationally efficient modified model predictive control (MMPC) method for AFE-rectifier based AC-DC-AC converter system, to eliminate the common-mode-voltage (CMV) without any degradation of harmonic profile of the load current, as well as to significantly reduce the computational time of the predictive algorithm. The proposed MMPC method is formulated in voltage domain rather than current domain as in traditional MPC method. In the proposed MMPC method, sector pre-determination is adopted, to reduce the available finite-control-set (FCS), which significantly reduces the computational time for the predictive algorithm. Also, CMV is eliminated by applying synchronization between the rectifier and inverter parts of AFE-rectifier based AC-DC-AC converter, when selecting the optimal switching combination for the next sampling interval. The proposed MMPC method is verified in MATLAB-Simulink. The results confirm that the proposed method achieve the following outcomes: significantly reduces the computational time, completely eliminates the CMV without degradation of harmonic content, and opens the door to improve the power quality in any CMV sensitive industry applications by utilizing faster sampling frequency.
This paper presents a solar energy processor based on Packed U-Cells inverter for grid applications. The proposed single phase multilevel inverter PUC allows the generation of 7-level output voltage. Two control techniques are used in this work. MPPT is applied on the PV in order to extract the maximum power, while the aim of MPC or the model predictive control is to balance three variables in the system; the grid current, the capacitor voltage in the PUC as well as the BOOST output voltage. The feasibility of the designed system is validated by simulation using Matlab-Simulink-SimPowerSystems.
Multi-terminal HVDC transmission based on the development of HVDC is an important way of power transmission of new energy in the future. But its control strategy is complex, especially the coordinated control between stations. A three-terminal parallel VSC-MTDC simulation model in the MATLAB/Simulink platform is built in the article. An improved model predictive control strategy with power self-coordination is put forward. A single converter station takes the model predictive control with power consumption as the cost function. And the coordinated control between converter stations is fulfilled by DC power control which is controlled by the cost function in model predictive control. Thus, coordinated control between converter stations and the control of converter are of organic combination through the cost function. When disturb occurs in any converter station except the main converter or one converter station is out of work, the main converter station provides the power compensation to ensure the system keep working, Without the need for additional coordinated controller design, greatly reducing the economic consumption, improving economic benefit. And each converter station is relatively independent, the system stability is better. In general, the simulation results prove the effectiveness of this method, which provides a new way for VSC-MTDC control.
A fixed switching frequency scheme for finite-control-set model predictive control is presented to achieve an output waveform quality that compares well to that of a pulse-width-modulator-based linear controller, while retaining the benefits of model predictive control. The controller is divided into two parts: the offline calculation and storage of the coefficients of the prediction equations and the online evaluation of the controller. The controller is experimentally evaluated on a five-level flying-capacitor converter.
Quasi-centralized direct model predictive control (QC-DMPC) scheme may serve as an effective alternative for back-to-back power converter in permanent magnet synchronous generator (PMSG) wind turbine systems. However, model errors and imperfect power efficiency lead to evident dc-link voltage tracking offset. This paper proposes a revised quasi-centralized direct model predictive control (RQC-DMPC) scheme for back-to-back converter PMSG wind turbine systems, within which, the dc-link voltage is directly controlled by a grid side predictive controller with a flexibly designed cost function using a revised dynamic reference generation concept. The dc-link voltage steady status tracking errors are eliminated. To reduce the computational efforts of the classical scheme, a computational efficient concept is incorporated into the proposed method. The proposed scheme is implemented on an entirely field programmable gate array-based platform. The effectiveness of the proposed method is verified through experimental data. The dc-link control performance comparison with classical proportional-integration controller-based methods and the QC-DMPC scheme under different scenarios are also experimentally investigated. The results emphasize the improvement of the proposed RQC-DMPC scheme.
The dc-link voltage fluctuation caused by the change of working state of the load motor has been one of the key issues in the pulse width modulation rectifier-inverter system. In this study, an improved model predictive control (MPC) scheme is proposed to address this problem. The MPC is applied to both the rectifier stage and the inverter stage in the system. Direct power control is used in the rectifier stage and the direct torque control is employed in the inverter stage, with the key novelty of the active power reference values being defined by both real-time and periodic compensation power based on the system-level power-balance model. Meanwhile, an MPC algorithm based on a two-step prediction is introduced to compensate for the delay of a digital controller. Comparison has been conducted between the proposed scheme and three other methods. Simulation and experimental results show that the proposed control scheme exhibits good performance in both the rectifier stage and the inverter stage with improved dynamic response and suppressed voltage fluctuation of the dc-link voltage.
El Batolito de Sabanalarga es a un cuerpo alargado de 410 Km2 que se extiende entre las Cordilleras Central y Occidental de Colombia, intruye en el borde occidental la Formación Barroso y las Diabasas de San José de Urama y en el borde oriental las rocas metamórficas del Complejo Cajamarca. El Batolito de Sabanalarga está formado por al menos dos pulsos magmáticos: uno inicial representado por gabros y dioritas de afinidad subalcalina toleítica y un segundo pulso constituido por cuarzodioritas y tonalitas de afinidad subalcalina de la serie calcoalcalina baja en K. El magmatismo se generó en un ambiente localizado por encima de la zona de subducción, en un arco volcánico plutónico localizado en el borde de sutura entre la corteza continental y la corteza oceánica, afectando ambas cortezas. Hace parte del arco las rocas volcánicas de la Formación Barroso. La edad del Batolito y del arco en general, en concordancia con los datos radiométricos, las relaciones intrusivas y el registro fósil, ocurrió dentro del rango comprendido entre el Cenomaniano-Aptiano superior, localizándose el plutonismo en el rango de edad entre 83 M.a y 102 M.a. Magmatismo como el de la Diorita de Altavista, el Gabro de San Diego y el Batolito Antioqueño, es contemporáneo con el arco que generó el Batolito de Sabanalarga, pudiendo ser parte del mismo evento magmático.
This paper proposes a novel and simple direct power control of three-phase pulsewidth-modulated (PWM) rectifiers with constant switching frequency using space-vector modulation (DPC-SVM). The active and reactive powers are used as the pulse width modulated (PWM) control variables instead of the three-phase line currents being used. Moreover, line voltage sensors are replaced by a virtual flux estimator. The theoretical principle of this method is discussed. The steady-state and dynamic results of DPC-SVM that illustrate the operation and performance of the proposed system are presented. It is shown that DPC-SVM exhibits several features, such as a simple algorithm, good dynamic response, constant switching frequency, and particularly it provides sinusoidal line current when supply voltage is not ideal. Results have proven excellent performance and verify the validity of the proposed system.
This work presents the application of predictive current control in a voltage source inverter. The method uses a discrete-time model of the system to predict the future value of the load current for all possible voltage vectors generated by the inverter. The voltage vector which minimizes the current error at the next sampling time is selected. The performance of the proposed predictive control method is compared with hysteresis and PWM control. The results show that the predictive method controls very effectively the load current and compares very well with the classical solutions.
While known modulation strategies for matrix converters are based on PWM or vector-modulation, this paper presents a novel time-discrete modulation method by which the switching state of the matrix converter is changed only at equidistant points in time. The decision about which switching state is to be set for the following sampling period, is made by use of a quality function. Using this approach, the switching state is selected in such a way as unity displacement factor is seen at the supply side whilst the load currents follow their reference values with good accuracy. The quality function mentioned above is determined via a mathematical model of the matrix converter and the controlled system. The one switching state that induces the optimum value of the quality function is selected for the next sampling interval. Measurements taken on a model plant, consisting of a matrix converter and a standard induction machine with a rated output power of 11 kW show that the matrix converter, equipped with the control method presented here, offers some advantages over systems with conventional frequency converters.
A voltage-sourced rectifier control scheme for use with AC/DC/AC
variable speed drives is presented. A control scheme is derived that
directly calculates the duration of time spent on the zero state and on
each switching state adjacent to the reference vector, over a constant
switching interval, in order to drive the line current vector to the
reference vector. In addition, under transient conditions, when deadbeat
control is not possible, a control scheme is presented that ensures that
the line current vector is driven in the direction of the reference
current vector. The current reference for the rectifier controller is
derived from the bus voltage error and a feedforward term based on the
estimated converter output power. The proposed space vector-based
rectifier regulator is shown to exhibit improved harmonic and transient
performance over existing per-phase duty cycle prediction methods,
especially at modulation indices near unity. The deadbeat control of the
rectifier input current is accomplished every half-cycle with constant
switching frequency while still symmetrically distributing the zero
state within the half-cycle period
This paper addresses a control method of reducing the size of the
DC-link capacitors of a converter-inverter system. The main idea is to
utilize the inverter operation status in the current control of the
converter. Specifically, the information on the load power is
incorporated in synthesizing the converter current control input so that
a proper DC voltage level is maintained. We describe the dynamics of
load current and apply feedback linearization theory to obtain an input
output linearized system. Theoretically, this control strategy is
effective in regulating the DC voltage level, even though the DC-link
capacitor is arbitrarily small and load varies abruptly. The superior
performance is demonstrated through simulation and experiment. An
experiment was performed with a 9-kW pulsewidth modulation
converter-vector inverter system having a 75-μF DC-link capacitor
This paper proposes a novel control strategy of a pulsewidth
modulation (PWM) converter with no power-source voltage sensors. The
strategy has two main features to improve a total power factor and
efficiency, taking harmonic components into account without detecting
the voltage waveforms. One feature is a direct instantaneous power
control technique for the converter, which has been developed to control
the instantaneous active and reactive power directly by selecting the
optimum switching state of the converter. The other feature is an
estimation technique of the power-source voltages, which can be
performed by calculating the active and reactive power for each
switching state of the converter from the line currents. A
digital-signal-processor-based experimental system was developed, and
experimental tests were conducted to examine the controllability. As a
result, it was confirmed that the total power factor and efficiency were
more than 97% and 93% over the load power range from 200 to 1400 W,
respectively. These results have proven the excellent performance of the
proposed system
The paper introduces the family of quasi-direct converters, i.e.,
forced-commutated AC/DC/AC power converters including small energy
storage devices in the DC link. In particular, the case of the
three-phase to three-phase quasi-direct power converter is considered.
Since energy storage minimization calls for instantaneous input/output
power balance, a proper control strategy is needed. The paper describes
a simple and effective control technique which also provides high-power
factor and small distortion of the supply currents. After a discussion
of the general properties of quasi-direct power converters, design
criteria of both power and control sections are given, and experimental
results of a 2-kVA prototype are reported
Generalized theory of the instantaneous reactive power in three phase circuits
- H Akagi
- Y Kanagawa
- A Nabae
H. Akagi, Y. Kanagawa, and A. Nabae, " Generalized theory of the instantaneous reactive power in three phase circuits, " in Proc. of IEEJ Int. Power Electronics Conference, IPEC, Tokyo, Japan. pp. 1375-1386. 1983. IAS 2005 939 0-7803-9208-6/05/$20.00 © 2005 IEEE