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System DG unit current waveforms with THD after compensation with active and passive filters: (a) system currents; (b) PV currents, (c) MT currents; (d) FC currents; (e) NLL 1 currents; (f) NLL 2 currents.
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In recent years, renewable energy sources have been considered the most encouraging resources for grid and off-grid power generation. This paper presents an improved current control strategy for a three-phase photovoltaic grid-connected inverter (GCI) under unbalanced and nonlinear load conditions. It is challenging to suppress the harmonic content...
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Renewable energy (RE) has become a focal point of interest as an alternative source of energy to the traditional fossil fuel and other energy sources due to the fact that it is more environmentally friendly, abundant and economically feasible. Many countries aggressively promote feed-in tariff schemes and solar photovoltaic (PV) systems have become...
Citations
... Classical control schemes, such as Proportional-Integral (PI) or Proportional-Integral-Derivative (PID), are widely employed in several engineering applications due to their straightforward implementation and efficient dynamic response when faced with changes to the reference signals [28]. However, to track sinusoidal references, such controllers must map the problem domain into Park or Clarke frameworks, which increases the number of required calculations [29]. ...
Open Access manuscript. Available at: https://doi.org/10.1016/j.heliyon.2024.e33019
... This controller's reign is demonstrated using comparison optimization [9] different methods, such as genetic and artificial bee colonies and particle swarm optimization (PSO), a grey wolf optimization procedure with adaptive controller [10], the system response contributes to the preservation of system wolf optimization [11]. The powerful meta-heuristic are grey wolf optimizer (GWO). ...
The renewable energy resources depend on environmental concerns. Photovoltaic (PV) systems are an interesting form of renewable energy resource. The two main problems associated with PV systems are nonuniformity of irradiation and temperature change. PV achieving maximum power point tracking are dependent on power electronics converters. Emissions are a key challenge for the future of conventional renewable energy resources, which play an important role in the generation system. It is crucial in applications and industry because the primary goal of optimization is to discover specific research. We offer using the population of search agents based on fitness, the multi-objective grey wolf optimizer, a more modern meta-heuristic based on the hunting habits and social structure of grey wolves, for optimizing adaptive controllers for failures in grid analysis and power system integration various faults in the grid cause several power quality issues. Harmonics, voltage sag and swell imbalances, and many power conditioning topologies. This was carried out using MATLAB/Simulink, and the results showed a superior and flexible performance in reducing voltage sag and voltage swell problems and imperfections at various loading situations.
... where = + and = + , and are the grid and inverter side resistance respectively and is the grid side inductance, while is the inverter side inductance [7], [14]. On the controller side, the decoupled condition is given as: ...
... Single-phase grid-connected power control in dq synchronous reference … (Ali Salam Al-Khayyat)7 ...
This paper presents the performance of controlling the active and reactive power of single-phase grid connected inverter by dq synchronous reference frame and space vector modulation (SVM) which is implemented by using field programmable gate array (FPGA) due to the flexibility they offer in comparison to other digital signal processors, hence it become the standard instruments for implementing various types of pulse width modulation (PWM) digital signal processors (DSPs). The SVM method has used because of its superiority in terms of harmonic distortion, switching losses and utilization of direct current (DC) bus. The synchronization is achieved by using second order generalized integrator (SOGI) due to its simple structure, certain filtering ability and frequency adaptability, in which the phase locked loop (PLL) ensures high performance for single-phase inverter. The active and reactive inverter current has been controlled and decoupled from each other and the dynamic response has been improved and became fast with proper feed-forward and decoupling grid voltage term. The system has simulated by MATLAB and the result shows robust control of injected grid current, active and reactive power control and DC link voltage control.
... Against this background, we proposed three-phase and single-phase inverters. These are no longer used to send pure sinusoidal current signals to the grid in phases [17]− [19]. To achieve these goals, the choice of these photovoltaic inverters is based on the equivalence between the reactive power supplied and the nominal power consumed by the grid, with the cost of these inverters. ...
Currently, the energy transfer process to the grid of the PV system is based on the importance of less harmonics and high efficiency. The evaluation of harmonics distortion of current is based on the value of THDi (<<5%), this last becomes very high if the current leakage is high, which causes losses of the grid and safety problems. Therefore, our job is to improve the classic control method of PV inverters used to reduce grid loss and improve electricity prices. This study is a proposal toward the modelization and improvement of the three-phase two-level, and multi-level photovoltaic (PV) inverter command, using space vector, and sinusoidal control based on controlling the active and reactive current delivered into the grid indirectly with a resonant controller (PIR) for a nonlinear load (NLL). The results of the simulations obtained by the new control methodology, SPWM, and SVPWM show that its performance is better compared with the simple modulation (PWM); the total harmonic distortion (THD) of current in both methods (SVPWM) and (SPWM) is better than that obtained with conventional commands. Also, multilevel converters control produces better quality waveforms, reducing current harmonic distortion.
... Synchronized or in-phase operation of the power electronic systems with the grid plays an important role in enhancing the overall operational efficiency of the system. Grid-synchronization technique extracts the parameters of the grid voltage signals which are then used inside the controller of grid-connected converters [1][2][3][4][5][6][7]. ...
A grid-synchronization-based fundamental frequency positive-sequence (FFPS) and negative-sequence (FFNS) amplitudes estimation technique is proposed for unbalanced and distorted grid. In this technique, the sequence amplitudes are extracted by extracting
the phase-angle of the FFPS and FFNS components. The extracted phase-angles have DC and double frequency AC components. The AC component is filtered out by using a Moving Average Filter (MAF) of appropriate window length. From the extracted phase-angle, the unknown frequency can be estimated by using a suitable controller.
A frequency-fixed equidistant samples-based pre-loop filter is also applied to eliminate the effect of measurement offset. The proposed technique has a very simple structure and is easy to tune. Small-signal modeling-based stability analysis and gain tuning procedure are also provided. The proposed technique strikes a good balance between
fast convergence and disturbance rejection capability. Comparative numerical simulation and experimental results with similar other techniques demonstrate the suitability and performance enhancement by the proposed technique.
... The line current components id and iq regulate the active and reactive power [25].First, feedback and feedforward signals are converted into dq-frame and then the current controller compensator produced the control signal in the dq-frame. Control signals are subsequently transmitted to the VSC's SPWM system in the abc-frame [26]. As a result, if the load current, Ioabc, is disrupted, the control goal is to regulate the amplitude and frequency of the load voltage, Vsabc. ...
... Proposed current controller diagram can be seen in Fig.14. In the dq-frame of SPWM, the reference voltage command signals to SPWM can be defined as follows [26]: where Vsd and Vsq are dq-coordinate of AC system voltages and id and iq are dq-coordinate of AC system current respectively. and are proportional and integral coefficients of current PI controller. ...
The microgrid is a small-scale, autonomous decentralized power plant with its own distributed generation, storage capacity and multiple loads, with the capacity to function in grid interconnected and an island mode. The decentralized control of microgrids with parallel operated voltage source converters (VSCs) is proposed in this paper to improve power quality using a machine learning approach. The DNN based MPPT controller is proposed and its best performance is presented. The SRF-PLL is utilized for AC side synchronization in VSC control. The proposed microgrid involves two PV arrays fed to two voltage source converters along with their independent controls, connected in parallel through LC filters and line coupling transformers and serves the loads at PCC. The proposed model is simulated using MATLAB/Simulink. The dq-framed inner loop control is employed to individually regulate the real and reactive power at the point of common coupling. Furthermore, the proposed model is analyzed and compared by employing a mathematical model of AC system dynamics, inner loop control, output voltage quality, AC harmonic spectrum analysis, and total harmonic distortion (THD) in both grid interconnected and island mode. In island mode, AC harmonic spectrum and THD are accomplished within the permissible range.
... So, the multitask option is preferred as detailed in [10], where frequency and voltage regulation at the PCC are taken into consideration. In [15][16][17], the synchronous reference frame technique (SRF) is proposed for standalone and gridconnected systems. The obtained results under the presence of nonlinear loads show satisfactory performance. ...
... The authors have succeeded to validate the proposed control for the off-grid system in real-time, and the obtained results show satisfactory performance. Compared to the SRF technique proposed in [15][16][17], or the instantaneous power theory, SMC is complex and requires an accurate technique to select the optimal SM gains (β 1 and β 2 ) to achieve high performance. ...
In this paper, a composite control strategy for improved off-grid configuration based on photovoltaic (PV array), a wind turbine (WT), and a diesel engine (DE) generator to achieve high performance while supplying nonlinear loads is investigated. To operate the WT efficiently under variable speed conditions and to obtain accurate and fast convergence to the maximum global operating point without a speed sensor, an iterative interpolation method is integrated with the perturbation and observation (P&O) technique. To ensure the balance of power in the system and to achieve the maximum power from the PV array without using any maximum power point tracking (MPPT) method, and ensuring stable operation during the disturbance, a double-loop control strategy for a two-switches buck-boost converter is developed. Furthermore, to protect the synchronous generator of the diesel generator (DG) from the 5th and 7th order-harmonics created by the connected nonlinear loads and to solve the issue of the filter resonance, the interfacing three-phase inverter is controlled using an improved synchronous-reference frame algorithm (SRF) with virtual impedance active damping. The presented work demonstrates effective and efficient control along with improved performance and cost-effective option as compared to the similar works reported in the literature. The performance of the presented off-grid configuration and its developed composite control strategy are tested using MATLAB/Simulink and validated through small-scale hardware prototyping.
... An improved, automatic, coordinated voltage control strategy performed by the authors in [18] combines the advantages of several controls which demonstrates a better control performance, especially in extreme environments. Furthermore, different strategies for controlling the distributed generators in terms of a current harmonic compensator [20][21][22] or unbalanced three-phase loads have been discussed and analyzed [23]. It is challenging to suppress the harmonic content below a pre-set value or to compensate for unbalanced loads [20]. ...
... Furthermore, different strategies for controlling the distributed generators in terms of a current harmonic compensator [20][21][22] or unbalanced three-phase loads have been discussed and analyzed [23]. It is challenging to suppress the harmonic content below a pre-set value or to compensate for unbalanced loads [20]. Similarly, a novel energy-management method for a grid-connected PV inverter is investigated. ...
This paper deals with photovoltaic (PV) power plant modeling and its integration into the medium-voltage distribution network. Apart from solar cells, a simulation model includes a boost converter, voltage-oriented controller and LCL filter. The main emphasis is given to the comparison of two optimization methods—particle swarm optimization (PSO) and the Ziegler–Nichols (ZN) tuning method, approaches that are used for the parameters of Proportional-Integral (PI) controllers determination. A PI controller is commonly used because of its performance, but it is limited in its effectiveness if there is a change in the parameters of the system. In our case, the aforementioned change is caused by switching the feeders of the distribution network from an open-loop to a closed-loop arrangement. The simulation results have claimed the superiority of the PSO algorithm, while the classical ZN tuning method is acceptable in a limited area of operation.
... According to the mathematical model of the three-phase GPV system as discussed [86], the output voltages of the inverter in the SRF are given by Equations (12) and (13) respectively. ...
... According to the mathematical model of the three-phase GPV system as discussed [86], the output voltages of the inverter in the SRF are given by Equations (12) and (13) ...
Renewable energy (RE) has become a focal point of interest as an alternative source of energy to the traditional fossil fuel and other energy sources due to the fact that it is more environmentally friendly, abundant and economically feasible. Many countries aggressively promote feed-in tariff schemes and solar photovoltaic (PV) systems have become one of the fastest growing RE sources that can be integrated into the grid distribution network. This paper reviews the recent development of grid-connected PV (GPV) generation systems comprising of several sub-components such as PV modules, DC-DC converter, maximum power point tracking (MPPT) technique, and an inverter. In addition, various grid synchronization and islanding detection methods are elaborated. The future key challenges to build a smart and efficient GPV generation system were also presented.
... The compensator gains, i.e., K p and K i are optimized using the automatic electronic voltage and current regulator (EVIR). An increase in the excitation current in the field winding of the generator causes the terminal voltage to increase 28 . The EVIR controls the voltage/current using power electronic devices; they are an actuator, exciter, generator, and sensor 29 . ...
... Moreover, to assess the performance of the proposed VI compensator, we also present an analysis using voltage and current waveforms along with a discussion on total harmonic distortion (THD) 25 . The proposed VI compensator is also compared with some of the recent state of the art PID based techniques including Naderipour et al. 28 , Trinh et al. 12 , Moussa et al. 33 , and Mousavi et al. 4 . ...
... Figure 7 shows the unit step response of the system as well as a comparison with the compensators proposed in existing literature 4 al. 28 , and Moussa et al. 33 show a sluggish response requiring 2.2, 2.9, 1, and 1.2 seconds, respectively. This shows that the proposed VI compensator achieves a steady state in the least amount of time. ...
Power quality is important for the reliable operation of power grids. Unwanted harmonics cause serious degradation of power quality. This problem is more obvious for distributed generations connected to a microgrid. To solve this issue, this paper proposes an improved voltage and current (VI) compensator to collectively suppress voltage and current harmonics in a three-phase hybrid fuel cell and photovoltaic grid-connected inverters using a synchronous reference frame (SRF) based technique in the presence of non-linear loads. It is shown that the proposed compensator can effectively reduce the harmonic contents in voltage and current without any dependence on offset devices such as active and passive filters. Simulations in MATLAB/Simulink show that the proposed control strategy not only reduces the total harmonic distortion to less than 5% (as per the IEEE 519 standard) but also results in the least total harmonic distortion (THD) as compared to existing techniques.
