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Active filters and energy storage systems operated under non-periodic conditions
Abstract
This paper describes power electronics technology relevant to
active filtering and energy storage for the purpose of power
conditioning. The combination of active filtering and energy storage
leads to a versatile system in terms of compensation under nonperiodic
conditions. However, energy storage is much more difficult and costly in
realization than active filtering because modern science offers only
chemical action, electromagnetic or electrostatic field, and kinetic or
potential energy as viable ways of energy storage. This paper is focused
on the present status of active filters, and energy storage systems for
power conditioning, along with a 200 MJ/20-MW flywheel energy storage
system which was commercially installed on a 66 kV power system for the
purpose of line-frequency regulation in 1996
... Several papers have dealt with the definition, characterization, and compensation of non-sinusoidal and non-periodic current/power [6]-[11]. However, most of the previous efforts have focused on the compensation of periodic, non-sinusoidal currents instead of non-periodic currents. ...
... A transient disturbance may also be considered as one kind of non-periodic current from the compensation point of view, e.g., the sudden addition of a large load to the system such as starting a motor or a fault. Several papers have dealt with the definition, characterization, and compensation of non-sinusoidal and non-periodic current/power [6][11]. However, most of the previous efforts have focused on the compensation of periodic, non-sinusoidal currents instead of non-periodic currents. ...
... The diversity of the features of non-periodic currents makes their compensation quite difficult, and theoretically, their compensation is very different from that of periodic distorted currents. However, in practice, these two cases may be quite similar to each other [11]. Generally speaking, after compensation, a sinusoidal source current with a constant rms magnitude is preferred for both cases. ...
This paper presents a new definition of non-active current, which is valid for single-phase and polyphase systems as well as for periodic and non-periodic waveforms. The definition is applied to a shunt compensation system, and different cases of non-periodic current compensation are studied. A variety of compensation characteristics of non-periodic currents and the rating requirements for the compensator are illustrated by simulation.
... Hirofumi Akagi [14] describes power electronics technology relevant to active filtering and energy store the purpose of power conditioning. The combination of active filter-and energy store-leads to a versatile system in terms of compensation under non-periodic conditions. ...
... In reference current generation scheme, reference current is generated by using the distorted wave form. Many control schemes are there for reference current generation, such as p-q theory[14,46], Indirect Current Control Theory, SRF theory, PLL controller and neural network etc. The Hysteresis current controller is principally used for providing gating pulse to the IGBT controller[36,37]. ...
Battery Energy Storage System (BESS) has emerged as one of the most promising technologies for power system use and is receiving increasing attention from power utilities. BESS is traditionally viewed by utilities as an option to supply peak load through load leveling, but there is now a growing recognition that the fast responses provided by the power electronics and microprocessor control within BESS offer a wide range of additional power system applications, such as back-up supply, power factor correction, energy managemait, power quality improvement and the ability to provide 'load shedding' during emergency operation conditions. In this Thesis, an improved integrated battery energy storage system (BESS) controller for distributed energy system is presented. The BESS is integrated in parallel with the full wave bridge converter into the distributed energy system network, hi a normal operating mode, the BESS serves as a power conditioner as well as an active power filter in a distributed power system network. This work presents BESS controller which is designed for regulating the state of charge of the batteries and also to manage the active power in a distributed power system network. The off peak load energy is used to recover the batteries' state of charge through the BESS controller, in this BESS controller, the Indirect Current Control theory. Instantaneous current control theory mode is used and also done study of Synchronous reference frame theory it helps to keep the batteries' state of charge conditions for improving the reliability of the distributed power system. This control strategy is incorporated into the main converter. The controller helps in managing the phase, amplitude and waveform of the current and voltage on the distributed power system network. The controller ensures the power quality and also assists in improving the power factor with respect to the utility for the intermittent distributed generation as well as the load. In this thesis, the proposed algorithm for the control of BESS system is verified by system analysis and simulation to demonstrate its improved performance while feeding a variety of loads in a distributed power system network.
... The voltage active filter can also be used in combination with current passive or active filters, improving the power quality, when carrying out functions of harmonic compensation in current and voltage, besides improving the power factor. The main characteristics of the series compensation equipments are: flexibility in the control, quick time of response, low maintenance cost, the equipment can compensate wide ranges of frequency, it can provide a continuous compensation range and it doesn't present resonance problems [15] [16]. To approach the power quality problems that affect the load operation within the distribution system, in this paper a dynamic voltage regulation device is proposed, which uses the tap changer principle, although incorporating the technology developed in the area of power electronics. ...
... The main characteristics of the series compensation equipments are: flexibility in the control, quick time of response, low maintenance cost, the equipment can compensate wide ranges of frequency, it can provide a continuous compensation range and it doesn't present resonance problems1516. To approach the power quality problems that affect the load operation within the distribution system, in this paper a dynamic voltage regulation device is proposed, which uses the tap changer principle, although incorporating the technology developed in the area of power electronics. ...
A device compensator able to help in improving the daily operation of an electric network by means of the sags and swells mitigation, as well as the correction of harmonic voltages is proposed. The device has been implemented in a laboratory prototype, where the control is carried out through a DSP. The preliminary results are promising and a bigger prototype is under construction.
... The disturbance may be caused by the sudden addition of a large load to the system such as starting a motor, a fault, or other reasons. Definition and compensation of non-sinusoidal and nonperiodic currents and power has been a concern for some time [6][11]. However, most of the previous efforts have focused on the compensation of periodic non-sinusoidal currents instead of non-periodic currents. ...
... The diversity of the features of non-periodic currents makes their compensation quite difficult, and theoretically, their compensation is very different than that for periodic distorted currents. However, from a practical point of view, these two cases may be very close to each other [11]. Generally, in both cases, a sine wave with a constant rms magnitude is preferred for the source current after compensation. ...
Based on a new definition of nonactive current/power, this paper presents the application of a parallel active filter for the compensation of nonperiodic currents. Analysis of the compensation characteristics required for a variety of nonperiodic currents such as those associated with arc furnaces is presented. In addition, the corresponding current rating and energy storage requirements of the compensator are also presented.
... A transient disturbance may also be considered as one kind of nonperiodic current, e.g., a sudden large load current such as starting a motor or a fault. Several papers have dealt with the definition, characterization , and compensation of nonactive current/power [6]–[11]. However, most of the previous efforts have focused on periodic, nonsinusoidal currents instead of nonperiodic currents. ...
... The diversity of the features of nonperiodic currents makes their compensation quite difficult, and theoretically, their compensation is very different from that of periodic distorted currents. However , in practice, these two cases may be quite similar to each other [11]. Generally speaking, after compensation, a sinusoidal source current with a constant rms magnitude is preferred for both cases. ...
... Time-domain based approaches are mostly originated from the Fryze power theory [10]- [11], instantaneous p-q theory [12]- [13,14], and synchronous d-q frame theory [15]. In [16] and [17] an extension of Fryze power theory, and instantaneous power theory is utilized for the compensation of non-periodic current. The time-domain based techniques have the advantage of being simple and instantaneous under some specific conditions. ...
This paper presents a new technique for the compensation of non-periodic load current. The method provides control references for three co-located devices, each corresponding to one moving calculation window and one decomposed part of the compensated current. They are slow compensator with high power rating, large calculation window, and low switching frequency; fast compensator with lower power rating, shorter calculation window, and higher switching frequency; and the reactive compensator which is an ordinary static VAR compensator (SVC). A fuzzy based adaptive window is proposed for the slow compensator to find the optimum window for different load characteristics. The technique is evaluated using real-world data and controller hardware-in-the-loop (HIL) implementation.
... Besides, adding FESS to a DG system can remove this problem. One of the basic commercial applications of FW in association with active filtering to develop frequency distortion on a high voltage power system line has been detailed in [209]. Dynamic voltage compensation on distribution feeders using FES has been investigated in [210]. ...
Energy storage systems (ESSs) play a very important role in recent years. Flywheel is one of the oldest storage energy devices and it has several benefits. Flywheel Energy Storage System (FESS) can be applied from very small micro-satellites to huge power networks. A comprehensive review of FESS for hybrid vehicle, railway, wind power system, hybrid power generation system, power network, marine, space and other applications are presented in this paper. There are three main devices in FESS, including machine, bearing, and Power Electronic Interface (PEI). Furthermore, advantages and disadvantages all of them have been presented. In addition a brief review of new and conventional power electronic converters used in FESS, have been discussed. Finally, practical ways to develop this technology in the future are presented.
... Applications of shunt active filters are expanding, not only into industry and electric power utilities but also into office buildings, hospitals, water supply utilities, and rolling stock [45][46][47][48][49]. ...
Decrease in the cost of power electronic devices and improvement in the efficiency of both power converters and energy storage components have increased the applicability of new technological solutions such as Custom Power (CP) and Flexible AC Transmission Systems (FACTS) Devices. Active Power Filter (APF) is one of the CP devices and can mitigate harmonics, reactive power and unbalanced load currents originating from load side. In this study, a comprehensive review of APF studies, the advantages and disadvantages of each presented techniques are presented. The study also helps the researchers to select the optimum control strategies and power circuit configuration for APF applications.
... The technique has fast response and simple implementation. But the current loop gain crossover frequency must be kept below the modulation frequency [43][44][45][46][47]. To overcome this limitation, this paper presents an effective scheme in Fig. 6 where filter currents are subtracted from ...
Non-linear load deteriorates the quality of current waveforms at the point of common coupling of various consumers. Active power filter (APFs) is used to mitigate the most concern harmonic pollution in an electrical network. The controller part is the nucleus of an active power filter configuration. Active power filter performance is affected significantly by the selection of current control techniques. The active filter and its current control must have the capability to track sudden slope variations in the current reference to compensate the distorted current drawn by the voltage source inverter. Therefore, the choice and implementation of the current regulator is more important for the achievement of a satisfactory performance level. In this survey, technical reviews of various types of controllers covering a wide range have been presented. This work also reveals the advantages and disadvantages of the practiced control strategies. The effectiveness of the study will help the researchers to choose the proper control methods for various applications of active power filter.
... Deste modo, é possível extrair energia do rotor, de forma eficiente, mesmo quando a tensão do sistema cai a valores muito baixos. Recentemente, a literatura tem apresentado exemplos de armazenadores do tipo " flywheel " , que se utilizam deste princípio [1][5][7]. De uma maneira geral, estes sistemas se baseiam na energia armazenada em volantes de inércia com massa pequena e girando a velocidades muito elevadas ou volantes com massa elevada girando a velocidades baixas. ...
... Deste modo, é possível extrair energia do rotor, de forma eficiente, mesmo quando a tensão do sistema cai a valores baixos. Recentemente, a literatura tem apresentado exemplos de armazenadores do tipo "flywheel", que se utilizam deste princípio (Ter-Gazarian, 1994) (Akagi, 2000) (Willis, 2000). De uma maneira geral, estes sistemas podem apresentar duas formas para armazenamento de energia: volantes girando a altíssimas velocidades com momento de inércia pequeno, ou girando a velocidades baixas com momento de inércia elevado. ...
This paper presents a flywheel energy storage system, which uses a switched reluctance motor/generator. It is shown how this device can be used either together with a DVR or alone in order to attenuate the effects of voltage sags and short interruptions. In order to improve the system efficiency, some design alternatives are presented. Finite elements analyses results, validated against laboratory measurements, indicate the advantages, for the intended application, of a suitable choice of ferromagnetic material. A commercial program was used to realize simulations, for the implementation of the control system. It is still suggested in this paper the use of a superconducting magnetic bearing for reduce energy lost, that is produced by frictions.
... Interaction with ac mains An interesting area of investigation is the operation of shunt active filters under unfavorable and realistic conditions of the electric system, as well as the practical limitations that are found [42]. In [43] a research of the behavior of an active filter under periodic and non periodic conditions of frequency is presented. Also, a study of the S-APF in real conditions of operation is presented [44]. ...
This work presents a survey of recent approaches which addresses solutions for current harmonic reduction in three phase three wire systems. The analyzed papers are the most representative solutions focused in to obtain unity power factor in the mains or to fulfil the regulations that are applied, the main comparison is done between shunt active power filters and PWM rectifiers. The revised solutions are varied and a classification according to their operating principle, input currents and output power is done. The main objective is to identify the advantages of each solution in particular
... Many of the loads encountered in modern power electronics cause a significant level of nonsinusoidal and/or nonperiodic voltage and current disturbances in electrical power systems. Arc furnaces, welders, and motor drives are typical nonlinear loads that can cause not only characteristic harmonics (frequency integer multiple of the line frequency) but also subharmonic (frequency lower than the line frequency) and stochastic nonperiodic (frequency higher than the line frequency but not the integer multiple of the line frequency) components to appear in the spectra of voltages and currents [1][2][3][4][5]. ...
This paper presents a 3-phase, 4-wire unified series-parallel active filter (USPAF) system for periodic and nonperiodic disturbance compensation using a generalized nonactive power theory. The USPAF system consists of a series active filter (AF), parallel AF, and split DC-link capacitors with the midpoint of the DC-link connected to the neutral wire. The generalized nonactive power theory is applicable to singlephase or multiphase, sinusoidal or nonsinusoidal, periodic or nonperiodic, and balanced or unbalanced electrical systems. The theory was implemented previously in a parallel AF. In this study, the USPAF system is proposed to compensate for the nonsinusoidal and nonperiodic currents and voltages. Distorted source voltages, source voltage sag, and unbalanced nonlinear load current compensation were simultaneously tested in the experiments. Subharmonic and stochastic nonperiodic current and voltage compensation were simulated in MATLAB/Simulink. Simulation and experimental results verified the validity of the generalized nonactive power theory for the compensation of periodic (nonsinusoidal) and nonperiodic current and voltage disturbances with the USPAF system.
... Nowadays, the microprocessor control and controllable highperformance power switches have turned the active filter to practical technology. According to Akagi (2000) over 1000 active filters are in use in Japan. ...
... Generally, the systems presently suggested to mitigate the effect of voltage sags rely on energy storage systems and one of them is that using the kinetic energy stored in the rotating parts of electrical machines, which has been generally referred to as"flywheel generator" (Bolen, 1992;Ter-Gazarian, 1994). These systems have been re-ceiving attention and are being proposed for voltage and frequency control (Weissbach et alli 1999;Akagi, 2000). ...
The wound rotor induction machine (WRIM) presents characteristics that make it attractive as an energy stor- age system where the energy is stored as kinetic energy in the rotor moving parts. When operating in the dou- bly fed mode (DFIM), with the rotor fed by a variable frequency power converter, the WRIM behaves as a syn- chronous machine, differing from the latter in the vari- able speed operation and larger dumping effect when subjected to disturbances. As the converter only needs to be designed to handle a fraction of the total power, the system can be used at a high level of power. This paper presents the analysis of a Doubly Fed Induction Machine (DFIM) used as a controlled active and reactive power compensator. The simulation and experimental results obtained show that this system can be used for voltage control in a power system as well as load-leveling device.
... The diversity of the features of non-periodic currents makes their compensation quite difficult, and theoretically, their compensation is very different than that for periodic distorted currents. However, from a practical point of view, these two cases may be very close to each other [9]. Anyway, in both cases a sine wave with a constant rms magnitude is preferred for the source current after compensation. ...
This paper presents a discussion of the compensation of non-periodic currents such as those associated with arc furnaces. Based on the compensation objectives for different types of load waveforms, the energy storage requirements of the compensator are also presented. Further, basic concepts required in the definition of nonactive current are presented and illustrated by simulations for a variety of different compensation characteristics of non-periodic currents. Key Words non-active power, reactive power, compensator, nonperiodic current, arc furnace 1.
... Many of the loads encountered in modern power electronics cause a significant level of nonsinusoidal and/or nonperiodic voltage and current disturbances in electrical power systems. Arc furnaces, welders, and motor drives are typical nonlinear loads that can cause not only characteristic harmonics (frequency integer multiple of the line frequency) but also subharmonic (frequency lower than the line frequency) and stochastic nonperiodic (frequency higher than the line frequency but not the integer multiple of the line frequency) components to appear in the spectra of voltages and currents12345. The harmonic currents will produce voltage distortions that can affect other sensitive loads at points of common coupling (PCC) as they interact with the impedance of an electrical distribution system. ...
This paper presents a 3-phase, 4-wire unified series-parallel active filter (USPAF) system for periodic and nonperiodic disturbance compensation using a generalized nonactive power theory. The USPAF system consists of a series active filter (AF), parallel AF, and split DC-link capacitors with the midpoint of the DC-link connected to the neutral wire. The generalized nonactive power theory is applicable to single-phase or multiphase, sinusoidal or nonsinusoidal, periodic or nonperiodic, and balanced or unbalanced electrical systems. The theory was implemented previously in a parallel AF. In this study, the USPAF system is proposed to compensate for the nonsinusoidal and nonperiodic currents and voltages. Distorted source voltages, source voltage sag, and unbalanced nonlinear load current compensation were simultaneously tested in the experiments. Subharmonic and stochastic nonperiodic current and voltage compensation were simulated in MATLAB/Simulink. Simulation and experimental results verified the validity of the generalized nonactive power theory for the compensation of periodic (nonsinusoidal) and nonperiodic current and voltage disturbances with the USPAF system.
... This storage is typically provided by capacitors whose cost may become prohibitive. In addition, if the storage is provided by a series bank of capacitors, control problems related to voltage balancing can become serious [3], [4]. A family of compensators was introduced in [5] that achieve power harmonic matching (PHM) on the line up to a selected (say L-th) harmonic. ...
The paper describes a set of Hilbert space-based analysis tools for reactive power compensation, and uses them to quantify the tradeoffs between line losses and compensator cost. Our method is illustrated on two polyphase examples, one involving a resistive circuit, and the other involving a nonlinear circuit (diode bridge rectifier) which is often encountered in industrial practice. The paper also addresses the issue of an efficient (order-recursive) computational procedure for the considered class of compensators.
... The diversified features of non-periodic currents make the compensation quite difficult, and theoretically, the compensation is different than that for periodic currents. However, practically the two cases are very similar [7], and in both cases a sine wave with a constant rms magnitude is preferred for the source current after compensation. If using a shunt active filter as the compensator, the compensator injects currents that are the difference between the desired source currents and the required load currents. ...
Compensation of irregular currents such as those associated with arc furnaces, transient disturbances, and power electronic converters is presented. The compensation is based on a well-defined nonactive current definition. The basic concepts required in the definition of nonactive current are presented and illustrated by compensation simulations for a variety of different types of nonperiodic currents found in distribution electrical systems, including disturbance, subharmonic, and stochastic currents. Further, based on the compensation objectives for different types of load waveforms, the specifications such as current ratings or capacitance requirements of the active filter are also presented.
... However, most of the previous efforts have focused on periodic nonsinusoidal systems, rather than non-periodic systems [2]. The p-q theory proposed in [3] is valid for three-phase three-wire systems with harmonics, and it has been extended to threephase four-wire systems45. In [6], Hilbert space techniques are adopted for the definition and compensation of reactive power. ...
This paper presents a generalized nonactive power theory, in which the instantaneous currents (active and nonactive) and instantaneous powers (active and nonactive) are defined. This theory is implemented in a parallel nonactive power compensation system. The theory is valid if the system is three-phase or single-phase, sinusoidal or non-sinusoidal, periodic or non-periodic, balanced or unbalanced. Four cases, three-phase balanced RL load, three-phase unbalanced RL load, diode rectifier load, and single-phase RL load are tested in the experiments. Subharmonic load compensation and non-periodic load compensation are simulated in Matlab. The simulation and experimental results not only verify the validity of the theory, but also show that this theory can perform instantaneous nonactive power compensation with fast dynamic response
... An interesting area of investigation is the operation of shunt active filters under unfavorable and realistic conditions of the electric system, as well as the practical limitations that are found [42]. In [43] a research of the behavior of an active filter under periodic and non periodic conditions of frequency is presented. Also, a study of the S-APF in real conditions of operation is presented [44]. ...
This paper presents a survey of recent approaches which addresses solutions for current harmonic reduction in three phase three wire systems. The analyzed works are the most representative solutions focused in to obtain unity power factor in the mains or to fulfil the regulations that are applied, the main comparison is done between shunt active power filters and PWM rectifiers. The revised solutions are varied and a classification according to their operating principle, input currents and output power is done. The main objective is to identify the areas of application of each solution in particular.
... The main characteristics of the series compensation equipments are: flexibility in the control, quick time of response, low maintenance cost, the equipment can compensate wide ranges of frequency, it can provide a continuous compensation range and it doesn't present resonance problems [15][16]. ...
A novel device based on power electronic is presented, designed to help in voltage regulation on the secondary feeder of distribution transformers, to help to mitigate the sag and swell phenomena, and for canceling harmonic voltages. The device is based in the injection of a series voltage with that of the own transformer. Such voltage is created by means of a voltage source converter (VSC) and controlled through a digital signal processor (DSP). Results obtained in a laboratory prototype and by simulation exhibit its applicability
... Generally, power electronic converters generate harmonic components with frequencies that are integer multiplies of the line frequency. However, in some cases, such as line commutated three-phase thyristor based rectifiers, arc furnaces and welding machines are typical loads, the line currents may contain both frequency lower than the line frequency (subharmonic) and frequency higher than the line frequency (stochastic non-periodic, the wave-shape and amplitude are constantly changing) components but not integer multiple of the line frequency [1][2][3][4][5]. These waveforms are considered as non-periodic, although mathematically the currents may still have a periodic waveform, but in any event, the period of the currents is not equal to the period of the line voltage [1,2]. ...
... The additional tasks consist of reactive power compensation, current harmonic reduction, load unbalance compensation, and smoothing of pulsating loads. In this way, the UPS behaves as a Power Conditioning System (PCS) when the grid supply is present, improving significantly the power quality in the grid section next to the Point of Common Coupling (PCC) [3]. Such a power conditioning system requires a storage device that is able to charge and discharge in a time between few seconds and one minute. ...
A power conditioning system with energy storage capability is proposed as a viable solution for improving the quality and the reliability of the electric energy supply. Several tasks can be performed at the same time, such as reactive power compensation, current harmonic reduction, and smoothing of pulsating loads. Moreover, the power conditioning system can operate as an uninterruptible power supply during short time interruptions of the grid supply. The proposed system is a flexible structure that can be coupled to several energy storage devices like batteries, flywheels, supercapacitors, superconductive magnetic energy storage systems. In order to show the power conditioning system performance, experimental tests have been carried out using a flywheel as storage device. The effectiveness of the proposed control system has been successfully verified in several operating conditions of the grid supply and of the load.
... The additional tasks consist of reactive power compensation, current harmonic reduction, load unbalance compensation, and smoothing of pulsating loads. In this way, the UPS behaves as a Power Conditioning System (PCS) when the grid supply is present, improving significantly the power quality in the grid section next to the Point of Common Coupling (PCC) [3]. Such a power conditioning system requires a storage device that is able to charge and discharge in a time between few seconds and one minute. ...
A power conditioning system with energy storage capability is proposed as a viable solution for improving the quality and the reliability of the electric energy supply. Several tasks can be performed at the same time, such as reactive power compensation, current harmonic reduction, and smoothing of pulsating loads. Moreover, the power conditioning system can operate as an uninterruptible power supply during short time interruptions of the grid supply. The proposed system is a flexible structure that can be coupled to several energy storage devices like batteries, flywheels, supercapacitors, superconductive magnetic energy storage systems. In order to show the power conditioning system performance, experimental tests have been carried out using a flywheel as storage device. The effectiveness of the proposed control system has been successfully verified in several operating conditions of the grid supply and of the load.
... However, most of the previous efforts have focused on periodic nonsinusoidal systems, rather than non-periodic systems [2]. The p-q theory proposed in [3] is valid for three-phase three-wire systems with harmonics, and it has been extended to threephase four-wire systems45. In [6], Hilbert space techniques are adopted for the definition and compensation of reactive power. ...
This paper presents a theory of instantaneous nonactive power/current. This generalized theory is independent of the number of phases, whether the load is periodic or non-periodic, and whether the system voltages are balanced or unbalanced. By choosing appropriate parameters such as the averaging interval T<sub>c</sub> and the reference voltage V<sub>p</sub>, the theory has different forms for each specific system application. This theory is consistent with other more traditional concepts. The theory is implemented in a parallel nonactive power compensation system, and several different cases, such as harmonics load, rectifier load, single-phase pulse load, and non-periodic load, are simulated in MATLAB. Unity power factor or pure sinusoidal source current from the utility can be achieved according to different compensation requirements. Furthermore, the dynamic response and its impact on the compensator's energy storage requirement are also presented.
... In active filters the effectiveness of filtering actions is strongly correlated with inverter control techniques and specifically to the algorithm for a real-time identification of the load harmonic content. A widely adopted approach is the Akagy-Nabae (p, q) instantaneous power theory that introduces instantaneous active and reactive power [16][17][18], starting from the instantaneous values of the voltages and of the currents. Another approach is due to Czarnecki [19][20][21] and is based on another orthogonal decomposition of the currents. ...
A calculus procedure is suggested based on integral transformations for obtaining a solution in a closed analytical form of the nonlinear mathematical model of active filters. The analytical solution expresses the reactive power and harmonic compensation of active filters as functions of filter parameters. Therefore this solution can be successfully used for obtaining design guidelines. The theoretical procedure is completed by a numerical analysis.
... If an FES system is included with a FACTS or custom power device with a dc bus, an inverter is added to couple the flywheel motor/generator to the dc bus. For example, a flywheel based on an ac machine could have an inverter interface to the dc bus of the custom power device, as shown in Fig. 5. Flywheel energy storage has been considered for several power system applications, including power quality applications [29]- [32] as well as peak shaving and stability enhancement [33]. ...
While energy storage technologies do not represent energy sources,
they provide valuable added benefits to improve stability power quality,
and reliability of supply. Battery technologies have improved
significantly in order to meet the challenges of practical electric
vehicles and utility applications. Flywheel technologies are now used in
advanced nonpolluting uninterruptible power supplies. Advanced
capacitors are being considered as energy storage for power quality
applications. Superconducting energy storage systems are still in their
prototype stages but receiving attention for utility applications. The
latest technology developments, some performance analysis, and cost
considerations are addressed. This paper concentrates on the performance
benefits of adding energy storage to power electronic compensators for
utility applications
Energy storage technologies do not represent energy sources; they provide valuable benefits to improve stability, power quality, and reliability of supply. Battery technologies have improved significantly to meet the challenges of practical electric vehicles and utility applications. Flywheel technologies are now used in advanced nonpolluting uninterruptible power supplies. Advanced capacitors are being considered as energy storage for power quality applications. Superconducting energy storage systems are still in their prototype stages but receiving attention for utility applications. The latest technology developments, some performance analysis, and cost considerations are addressed. This paper concentrates on the performance benefits of adding energy storage to power electronic compensators for utility applications.
Keywords—Battery energy storage, custom power, energy storage system, flexible ac transmission systems (FACTS), flywheel energy storage, high voltage dc transmission (HVDC), hyper capacitor, power electronics, super capacitor.
In this paper is presented the behavior of an Active Front End Converter in the presence of power quality problems. After spending a brief review of the problems related to power quality such as [1] voltage sags, harmonics, repetitive conducted noises of common type caused by load switching, distributed generation, power factor correction, and the noise suppression to the grid in the range 2kHz –20kHz. It is therefore presented a control model to reduce these disturbances, obtained through the algorithms studied by Akagi [2]; the results obtained by simulation are presented for each of these causes.
In this chapter, the basic principles for parallel power electronics filters are discussed. In Sect. 2.1, the influences of reactive power, harmonics and unbalance are given, which affect and degrade the practical power network. The basic circuit configuration for injecting and absorbing compensating current is discussed. Furthermore, several parallel power filters are given and compared. In Sect. 2.2, instantaneous power theories which are important for detecting the compensation current components and controlling the fast response of power electronic compensators are introduced and addressed. Finally, different power electronic converters are discussed and compared in Sect. 2.3. The effect of dc voltage variation on the switching functions are also introduced in Sect. 2.3.
The distribution feeders often get overloaded under peak power demands. This situation is generally countered by load shedding, which leads to financial losses to utilities and individual users. The compensation of real/reactive power not only provides the voltage profile improvement but also ensures the sustain power to the consumers. This paper presents the new control algorithm to support the real and reactive load power demand by integrating energy storage (ES). The efficiency functions co-relates to the thermal limit and storage energy availability. For a given radial feeder this control algorithm ensures the unity power factor on source side which provides relief in reactive power support from the source. The energy saving due to loss reduction and reliability of supply for critical load justify the additional energy storage investment. This algorithm is implemented with the energy storage system along with the DSTATCOM. The performance of the controller is observed using MATLAB/SIMULINK.
The necessity for compensation for induction motor three-phase active power and electromagnetic torque oscillating components caused by its asymmetry and nonlinearity is grounded. A method of these components compensation by means of variable-frequency electric drive is offered. Expressions for determination of corrective voltage for compensation for oscillating components of three-phase instantaneous active power and electromagnetic torque are substantiated. The efficiency of the offered method is demonstrated on the basis of the results of modeling the operation of variable-frequency electric drive with an asymmetric induction motor. It is shown that the application of this method additionally results in decrease of thermal overload at particular phases.
Before power electronics were developed, non-periodic currents used to occur in distribution systems, apart from arc furnaces supply, mainly during switching and faults. Now, such currents are produced at normal operation of some power electronics equipment. Power electronics enables very fast control of processes and energy flow. Non-periodic currents are by-products of such a fast control. Non-periodic currents in electrical power systems occur as an effect of deformation or conversion of periodic, usually sinusoidal voltage and the periodic component of the supply current is crucial for permanent transfer of energy from generators to loads. Such non-periodic current, with a periodic or quasi-periodic components are referred to as semi-periodic currents in this paper. The paper provides fundamentals of semi-periodic current compensation and discusses a control algorithm of such a compensator.
In this paper, a generalized non-active power theory based control strategy is implemented in a 3-phase 4-wire combined series-parallel active filter (CSPAF) system for periodic and non-periodic waveforms compensation. The CSPAF system consists of a series active filter (SAF) and a parallel active filter (PAF) combination connected a common dc-link. The generalized non-active power theory is valid for single-phase and multi-phase systems, as well as periodic and non-periodic waveforms. The theory was applied in previous studies for current control in the PAF. In this study the theory is used for current and voltage control in the CSPAF system. The CSPAF system is simulated in Matlab/Simulink and an experimental setup is also built, so that different cases can be studied in simulations or experiments. The simulation and experimental results verify that the generalized non-active power theory is suitable for periodic and non-periodic current and voltage waveforms compensation in the CSPAF system.
This paper presents a general definition of nonactive current/power and the implementation for a shunt compensation system. This definition is universal for different loads, such as nonperiodic, unbalanced or single phase, and also flexible in terms of the compensation results. Unity power factor, pure sinusoidal source current, or zero nonactive power supply from the utility can be achieved according to different compensation requirements. In addition, the corresponding current rating and energy storage requirements of the compensation system are also presented.
The paper deals with sample structures of active filters. The aim is the evaluation of an analytical model for analysing the influence that filter parameters have on behaviour of the device. The results give also the opportunity to carry out useful guidelines for filter design. By means of well-known mathematical procedures the traditional mathematical model of active filter is arranged to be suitable of an analytical solution of the system of differential equations. Solutions are expressed as a function of the time and by means of inner parameters. Therefore it is possible a simple evaluation of the influence of the parameter values on output filter currents.
This paper explores the use of a wound rotor doubly fed induction machine (DFIM) as a controlled active and reactive power compensator, for voltage control in a power system as well as load-leveling device, combining the characteristics of a synchronous condenser and those of a low speed flywheel generator. Firstly an analytical model of the DFIM is presented, which is used to demonstrate how the power factor of the stator winding can be controlled with the converter. This analysis is confirmed with simulations. Secondly, a vector control scheme is presented which de-couples the reactive and active power control. This control is validated with SABER simulations.
Summary from only given. Active filters are installed in parallel or in series with harmonic sources, combined with passive filters or integrated into unified power quality conditioners. Each configuration has its own advantages and limitations. Given the current status of electromagnetic transients programs, only an idealized representation of the power circuit of an active filter is possible. This is an important limitation for filter design; however, it allows users to analyze very accurately the interaction between the filter and the power system. This paper includes a complete case study with the application of an active filter for harmonic and reactive power compensation
Conventionally, harmonic filters have hitherto been used to reduce the very undesirable effects of current harmonics in the input current to convertor equipment. The present paper describes an investigation into a new method of eliminating these current harmonics at the source, this being a more fundamental method than merely suppressing their consequences. The cost of the new method is not likely to be more expensive than elaborate filter equipment. The process consists of modifying the primary current waveform by the injection of triple-frequency currents into the convertor. An explanation of the fundamental action is presented, together with an analysis of the effects of triple-frequency current injection upon the harmonics generated by duplex convertor equipment.
Attention has been paid to active filters for power conditioning which provide the following multifunctions: reactive power compensation; harmonic compensation; flicker/imbalance compensation; and voltage regulation. Active filters in a range of 50 kVA-60 MVA have been practically installed in Japan. In the near future, the term "active filters" will have a much wider meaning than it did in the 1970s. For instance, active filters intended for harmonic solutions are expanding their functions from harmonic compensation of nonlinear loads into harmonic isolation between utilities and consumers, and harmonic damping throughout power distribution systems. This paper presents the present status of active filters based on state-of-the-art power electronics technology, and their future prospects and directions toward the 21st Century, including the personal views and expectations of the author
The authors have developed and proposed a novel active filter
system composed of an inverter bypass circuit for the suppression of
harmonic resonance conditions caused between the inductance behind the
load bus and the capacitance of VAr equipment, especially at lower
harmonic frequencies. They have installed this new harmonic compensation
system in combination with TCR-type SVC and shunt LC filters at the
Yamanashi Maglev test line. Here, they describe the outline of the
reactive power and harmonic compensation systems, and harmonic resonance
test results which show satisfactory performance of the active filter
This paper proposes a synchronous reference frame based controller
for a hybrid series active filter system. A hybrid series active filter
system has been designed, built and installed at Beverly Pump Station in
New England Electric utility for 765 kVA adjustable speed drive load to
meet IEEE 519 recommended harmonic standards. The series active filter
is rated 35 kVA-4% of the load kVA, and is controlled by a synchronous
reference frame based controller to act as a harmonic isolator between
the supply and load. This paper discusses the basic synchronous
reference frame controller structure and addresses its operation under
nonunity controller loop gain conditions. Design trade-offs and
implementation issues of the synchronous reference frame controller are
discussed. Operation of the hybrid series active filter system under
off-tuned passive filter conditions and its impact on the performance of
the synchronous reference frame based controller is experimentally
evaluated. Effectiveness of the series active filter to provide harmonic
damping and the use of simpler and low cost power factor correction
capacitors as passive filters, is demonstrated by laboratory
experimental results. Field installation and laboratory experimental
results demonstrate the practical viability of the synchronous reference
frame based controller for hybrid series active filter to provide
harmonic isolation of nonlinear loads and to comply with IEEE 519
recommended harmonic standards
The control strategy of active power filters using switching devices is proposed on the basis of the instantaneous reactive power theory. This aims at excellent compensation characteristics in transient states as well as steady states. The active power filter is developed, of which the power circuit consists of quadruple voltage-source PWM converters. As the result, interesting compensation characteristics were verified experimentally which could not be obtained by the active power filter based on the conventional reactive power theory.
The conventional reactive power in single-phase or three- phase circuits has been defined on the basis of the average value concept for sinusoidal voltage and current waveforms in steady states. The instantaneous reactive power in three-phase circuits is defined on the basis of the instantaneous value concept for arbitrary voltage and current waveforms, including transient states. A new instantaneous reactive power compensator comprising switching devices is proposed which requires practically no energy storage components.
A novel approach to compensating for harmonics in power systems is
presented. It is a combined system of a shunt passive filter and a small
rated series active filter. The compensation principle is described, and
some filtering characteristics are discussed in detail. Excellent
practicability and validity to compensate for harmonics in power systems
are demonstrated experimentally. Although the source harmonic voltage
was only 1%, the source harmonic current reached about 10% before the
series active filter was started. After it was started, no harmonic
current flowed into the shunt passive filter. In addition, no harmonic
voltage appeared at the terminals of the shunt passive filter, because
the source harmonic voltage was applied to the series active filter. The
total loss of the series active filter was less than 40 W. It is
concluded that the combined system is far superior in efficiency to
conventional shunt active filters
Active ac power filters
- L Gyugyi
- E C Strycula
Self-commutated static var generators at Shintakatsuki substation
- A Iizuka
- M Kishida
- Y Mochinaga
- T Uzuka
- K Hirakawa
- F Aoyama
- T Masuyama
Successful commercial operation of doubly-fed adjustable-speed flywheel generating system
- T Nohara
- H Senaba
- T Kageyama
- T Tsukada