Sinusoidal Grid Currents Research Articles

Parameter‐free predictive control with flexibility in power adjustment for grid‐connected converters under unbalanced grid conditions

AbstractThis paper introduces a novel finite control set predictive direct power control method for grid‐connected converters without cost function evaluations. Unlike conventional predictive direct power control, since the proposed method does not use the model parameters, their uncertainties do not cause prediction error and inappropriate voltage vector selection. The method employs a new form of voltage vector selection based on the slopes of active and reactive powers. The slopes are predicted in a manner with a low sensitivity to sampling noise, without updating a look‐up table, and recursive methods. Hence, there are no stagnation and convergence issues. Also, the proposed method avoids startup problems caused by data‐lacking due to directly regulating the active and reactive power by a switching logic. Flexible power oscillations control with balanced sinusoidal grid currents without any signal sequence extraction can also be achieved under this method in unbalanced grid conditions. The proposed method is assessed by both simulation and experimental studies, and its performance is compared with existing robust combined and model predictive control methods. The outcomes highlight the influence of the proposed approach and establish its superiority over the other considered methods.

High-Efficient Direct Power Control Scheme Using Predictive Virtual Flux for Three-Phase Active Rectifiers

In recent years, the pulse-width-modulation (PWM) converter has been found to have extensive applications in renewable energy, industrial fields, and others. The high efficiency requirement is crucial to operating a PWM rectifier in various applications, in addition to the fundamental control objectives of sinusoidal grid currents and the correct DC bus voltage. Additionally, in practical application, another issue arises when the grid voltage frequently experiences distortion, leading to a distorted grid current and a significant rise in total harmonic distortion (THD). To resolve these problems, a model predictive virtual flux-based direct power control (MPVFDPC) with improved power loss performance is proposed based on an integrated switching state predetermination strategy. The proposed MPVFDPC for PWM rectifier inherits the merits of both virtual flux control and direct power control, which have fast dynamic performance and the grid current THD is considerably decreased under distorted grid voltage states. The proposed technique aims to minimize switching loss under ideal and distorted grid voltage states by exploiting the discontinuous modulation concept by using a switching state predetermination strategy. The MPVFDPC with switching state predetermination strategy is proven by employing it in experiments as well as simulations in comparison with previous models: predictive direct power control (Conv. MPDPC) and conventional MPVFDPC (Conv. MPVFDPC). The acquired waveforms and quantitative data are employed to prove the effectiveness of the developed algorithm.

Implementation of an adaptive control approach in a single‐phase grid‐tied solar photovoltaic system for power quality improvement

SummaryThis work focuses on a novel single‐phase complex band‐pass filter‐based frequency‐locked loop (1ϕ‐CBF‐FLL) control for a grid‐tied solar photovoltaic array (SPVA)‐based energy generating system. Among the novel characteristics of this 1ϕ‐CBF‐FLL control algorithm are as follows: (1) It offers a quick convergence rate; (2) it has the ability to mitigate harmonics and DC offset; and (3) it has simplicity in execution. A voltage source converter (VSC), boost converter, 1‐ϕ grid, ripple filter, and nonlinear loads are all part of the system. Feeding 1‐ϕ nonlinear loads and the grid with active power from the solar array is managed by the VSC. Furthermore, grid current quality is enhanced by the use of VSC. Between the solar array and DC‐link capacitor, there is a boost converter that uses the perturb and observe (P&O) technique to track the maximum power from the SPVA. The primary aim of the proposed system is to remove power quality (PQ) issues brought on by nonlinear and imbalanced loads and to supply sinusoidal grid currents during solar irradiance fluctuations. Additionally, a comparison between 1ϕ‐CBF‐FLL control and other control algorithms is presented. The effectiveness of this 1ϕ‐CBF‐FLL control is examined under varying nonlinear loads and in various environmental settings. Test results are used to confirm the simulated results of the proposed system. According to the IEEE‐519 standard, the recommended control may achieve a source current of total harmonic distortion (THD) of 4.02%, which is lower than 5%, a source voltage of THD of 3.21%, and a load current of THD of 24.54%.

New single‐stage bidirectional three‐phase ac‐dc solid‐state transformer

AbstractHigh‐power applications with low‐voltage (LV) dc loads, for example, fast charging stations for electric vehicles (EVs), are typically supplied from the medium‐voltage (MV) grid. Aiming for low volume, MVac‐LVdc solid‐state transformers (SSTs) that provide galvanic separation with medium‐frequency transformers (MFTs) are thus considered, which are conventionally realized as two‐stage systems that consist of an ac‐dc power‐factor‐correction (PFC) rectifier and an isolated dc‐dc converter. This letter extends a new single‐stage isolated bidirectional PFC rectifier concept to MV levels, resulting in an SST that performs MVac‐LVdc conversion in a single converter stage and, unlike many modular SST concepts, employs only a single MFT. The SST's primary side operates modular‐multilevel‐converter (MMC) bridge legs, whose input voltages contain large ac components, in the quasi‐two‐level mode to minimize the cell capacitors. The secondary side employs a standard LV three‐phase rectifier, and a dual‐active‐bridge‐(DAB)‐like modulation strategy allows power flow regulation and ensures sinusoidal grid currents. The concept is explained and validated using detailed circuit simulations of an exemplary 1‐MW system operating between a 10‐kV three‐phase grid and an 800‐V dc output. The component stresses are evaluated, and an efficiency of 98.1% and a power density of up to 0.6 kW/dm3 are estimated.

Multimode Control for Power Quality Improvement in an Electronically Coupled Distributed Generation Unit Under Grid Connected and Autonomous Modes

This paper develops a new multimode control strategy for power quality (PQ) improvement in distributed generation (DG) units that employs a voltage source converter (VSC) as the electronic interface medium. The devised control strategy seamlessly operates for both the grid connected (GC) and autonomous/stand-alone (SA) modes of microgrid (MG). A novel computationally efficient comb-filter driven discrete time oscillator is developed for current reference generation (CRG) under GC operation. It constitutes a cluster of zeros to introduce notch peaks at integer multiples of the fundamental frequency thereby ensuring improved harmonic rejection capability. Consequently, it ensures unconditionally balanced and sinusoidal grid currents with improved PQ to comply with grid interconnection codes prescribed in the IEEE std-519 and std-1547 even under electrical anomalies. In the SA mode, the CRG scheme is developed in a stationary reference frame with an improved vector proportional integral (VPI) compensator. Despite the uncertainty of load parameters, the proposed VPI guarantees zero steady-state error and superior transient response. A finite state machine-based synchronization framework is proposed to ensure secure and seamless transfer of MG between GC and SA even under disturbances. The practical viability of the proposed multimode control has been demonstrated by applying various switching rules in both GC and SA modes of MG operation.

A novel proposal for harmonic compensation in the grid-connected photovoltaic system under electric anomalies

The accurate estimation and online calibration of the fundamental weight components (FWC) from harmonically contaminated load current is crucial to evaluate the performance of grid-integrated photovoltaic (PV) units especially when exposed to grid anomalies. Driven by this motivation, an adaptive regularized least logarithmic absolute difference (RLLAD) filter is proposed for FWC estimation during nonlinear loading. The proposed filter pertinently captures the FWC of the harmonically distorted load currents. The resulting FWC guarantees balanced and sinusoidal grid currents even under disturbances in the grid voltage and load current thereby achieving different power quality (PQ) improvement targets i.e., grid current balancing and harmonic suppression, active and reactive power management, neutral current compensation, and power factor correction. The proposed RLLAD filter ensures comparable convergence performance and minimum steady-state oscillations in the grid reference currents. Proceeding further, to counter the nonlinearity introduced by the PV array, a feed-forward compensator is judiciously equipped. From a practical standpoint, it ensures superior DC-link voltage stabilization especially under abrupt transition in solar insolation level. The performance of the RLLAD filter is comprehensively assessed through numerical simulations in MATLAB/Simulink software. Furthermore, the practical viability of devised RLLAD filter is confirmed under rigorous experimental scenarios through OPAL-RT control suite. The experimental results demonstrate practicability of the proposed adaptive RLLAD filter and thus, considered to be a promising solution as compared to existing benchmarks and state-of-the-art approaches for online FWC estimation and PQ improvement. Most importantly, in terms of nonlinear load tracking capability, the proposed RLLAD filter is shown to outperform the classical LLAD filter with a response speed of less than 400 μs.

Adaptive qXE-LMF Filter for Improving Power Quality Using Grid-Supporting Photovoltaic System

In practice, nonlinear electrical loads pose various power quality (PQ) challenges. Driven by these challenges, a parallel combination of a nonlinear load and a photovoltaic (PV) inverter with adaptive quantum normalized-least mean fourth ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> XE-LMF) filter is proposed and experimentally validated to detect and compensate for the harmonics in harmonically contaminated currents. A scheme with an adaptive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> XE-LMF using fundamental weight components is used to generate the harmonics in the inverter output current thereby improving the PQ of the grid supply. The resulting grid current is pure and balanced; the PV inverter connected in parallel with the nonlinear load provides reactive and harmonic current support. Practically, the adaptive feature enables the online learning of filter weights of the load current harmonics to guarantee unconditionally balanced sinusoidal grid current. The proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> XE-LMF filter ensures fast convergence and minimum steady-state oscillations in the grid reference currents. An improved anti-windup PI compensator is used to ensure dc-link voltage stabilization. The practicality of the proposed adaptive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> XE-LMF filter is experimentally demonstrated using a three-phase four-wire uncontrolled rectifier-based nonlinear load. The experimental results also demonstrate the robustness of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> XE-LMF filter against changes in solar insolation level and nonlinear loads.

A variable step size robust normalized least mean absolute third‐based control scheme for a grid‐tied multifunctional photovoltaic system

SummaryThis paper develops a variable step size robust normalized least mean absolute third (VSSRNLMAT)‐based control scheme for a three‐phase grid‐tied multifunctional photovoltaic system (GTMPVS). The GTMPVS delivers PV power to grid‐connected loads and feeds excess power to the grid through a voltage source converter (VSC) when PV power is available. It enhances power quality (PQ) by mitigating current harmonics and compensating for an unbalanced load and reactive power simultaneously. The proposed control scheme accurately extracts the fundamental active and reactive weight components of nonlinear load current. The power exchange at the grid side occurs with balanced and sinusoidal grid currents. During the absence of PV power, the VSC continues its operation as a distribution static compensator (DSTATCOM), thus increasing the effective utilization of the power electronic switches employed in the VSC. The GTMPVS model is created in MATLAB/Simulink. The response of GTMPVS is observed under steady‐state and dynamic operating conditions while feeding power to a nonlinear load. The dynamic operating conditions are created by a change in solar irradiation and an unbalanced nonlinear load. Further, the proposed VSSRNLMAT control scheme is compared with some of the other adaptive filtering‐based control schemes, including least mean square (LMS), least mean fourth (LMF), least mean absolute third (LMAT), and normalized LMAT (NLMAT) in terms of convergence, oscillations, mean square deviation (MSD), computational complexity, and grid current total harmonic distortion (THD). It is found that the VSSRNLMAT control scheme offers THD of grid current as per IEEE‐519 standard. The proposed control scheme is implemented to operate the laboratory‐developed GTMPVS to verify the simulation results.

Sliding Mode Controller with Disturbance Rejection for Bidirectional Transformerless AC/DC Converter in EV Onboard Charger

Transformerless power converters are trending in automotive sector as the demand for onboard chargers rises. The high efficiency and leakage current mitigating property of highly efficient and reliable inverter concept (HERIC) converter make it an excellent choice among transformerless topologies. By using appropriate modulation technique, the HERIC converter can transmit bidirectional power. This article presents design of sliding mode controller (SMC) for bidirectional HERIC converter to enhance the tracking performance. The SMC parameters are selected utilizing Harris hawks optimization (HHO) algorithm. During vehicle-to-grid (V2G) operation, sliding mode controller is developed for reactive power regulation of the grid connected HERIC converter and for grid-to-vehicle (G2V) operation, the converter is operated with very low voltage ripples in the DC side. The stability analysis is done by considering model uncertainties to guarantee sinusoidal grid current, low THD, and unity power factor even in the presence of grid disturbances and parametric variations. The Typhoon Hardware in the Loop (HIL) 402 device is used to execute the real-time testing. The results confirmed the efficacy and robustness of the designed controller under different scenarios for both modes of operation.

PROPORTIONAL INTEGRAL QUASI RESONANT CONTROLLER FOR ZERO-SEQUENCE CIRCULATING CURRENT AND RIPPLES SUPPRESSION IN PARALLEL THREE-PHASE PWM RECTIFIERS

Parallel three-phase pulse with modulation (PWM) rectifiers with common sc and ac buses are widely used in power systems due to their many advantages such as flexibility, sinusoidal grid currents, lower switching frequency, and good reliability. However, this topology suffers from zero-sequence circulating current (ZSCC) generated by numerous reasons including filters inductors unbalanced, unequal dead time, and losses of synchronism between the control of each rectifier, which will distort the ac-side currents and increase power losses. This paper proposes both an adjusted space vector pulse width modulated (ASVPWM) method and proportional integral quasi resonant controller (PIQRC) method not only to force the ZSCC to be zero but also to reduce its ripples, which results in low frequency harmonic components in the ac side currents. This twofold objective can be achieved by adjusting the zero-vector duty ratios of ASVPWM to suppress the ZSCC and by using PIQRC to mitigate its predominant harmonics. Finally, the superiority and efficiency of the proposed control method in terms of ZSCC suppression and current ripple reduction are verified through comparative analysis with the conventional ZSCC-PI controller.

Switched-capacitor-based five-level inverter with closed-loop control for grid-connected PV application

Multilevel inverters (MLIs) have received a lot of attention in the power sector. The use of MLI to improve the power quality and performance of photovoltaic (PV) systems has increased significantly. The layout, expense, and voltage stress of an MLI connecting PV device are the main MLI constraints that must be optimized. This paper describes a five-level (5-L) inverter interfacing a single-stage tied to the grid to a PV system with a feedback control technique and a lower component count. The inverter will generate a higher voltage at the inverter output, indicating that it can raise the voltage. To prove the supremacy of the 5-L switched capacitor (SC) inverter, a comparative analysis is performed. A 3.424 kW PV system is used to test the feasibility of the 5-L SC inverter. The feedback control approach ensures that appropriate power monitoring, voltage balancing, proper SC inverter functioning, and the injection of clean sinusoidal grid current are maintained regardless of the dynamic changes that may occur. A 5-L SC inverter structure is used to do a thorough MATLAB/Simulation and experimental study.

Control and Performance of 240-Clamped Space Vector PWM in Three-Phase Grid-Connected Photovoltaic Converters Under Adverse Grid Conditions

This article evaluates the performance of a relatively new pulsewidth modulation (PWM) method i.e., 240 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> -clamped space vector PWM (240CPWM), in three-phase grid-connected photovoltaic (PV) converters under various grid voltage conditions. 240CPWM is a minimum switching loss PWM method that reduces the switching loss by 85% at unity power factor and has better total harmonic distortion (THD) as compared to conventional space vector PWM. A unique six-pulse dynamically varying dc-link voltage is required for 240CPWM. Typically, a three-phase grid-connected PV system consists of a dc–dc stage followed by a dc–ac stage. In this article, the dc–dc stage is operated in closed-loop control to shape the dynamic dc-link voltage required for 240CPWM. The dc–ac stage is operated in the current control mode using a proportional–integral controller along with a harmonic compensator to ensure sinusoidal grid currents along with maximum power point tracking. The modulation index of the dc–ac stage is uncontrolled and fixed at the maximum value, and the primary control mechanism changes the magnitude, phase, and wave shape of the dc-link voltage. The coordinated control of dc–dc and dc–ac stages is ensured for better dynamic performance and grid support functions. Finally, the performance of the grid-connected PV converter with 240CPWM is validated using a three-phase 3-kW 208-V hardware prototype under nonunity power factors, voltage unbalance, and voltage sag/swell conditions for the first time. The implemented control with 240CPWM achieves smooth operation under nonunity power factor and grid voltage disturbance conditions with THD as low as 3.5% and peak combined efficiency of dc–dc and dc–ac stages as 96.4%.

Hybrid MLI Topology Using Open-End Windings for Active Power Filter Applications

Different multilevel converter topologies have been presented for achieving more output voltage steps, hence improving system performance and lowering costs. In this paper, a hybrid multilevel inverter (MLI) topology is proposed for active-power-filter applications. The proposed MLI is a combination of two standard topologies: the cascaded H-bridge and the three-phase cascaded voltage source inverter. This configuration enhances the voltage levels of the proposed MLI while using fewer switches than typical MLI topologies. The proposed MLI was developed in the MATLAB/Simulink environment, and a closed-loop control technique was used to achieve a unity power factor connection of the PV modules to the grid, as well as to compensate for harmonics caused by nonlinear loads. To demonstrate that the configuration was working correctly and that the control was precise, the proposed MLI was constructed in a laboratory. A MicroLabBox real-time controller handled data acquisition and switch gating. The proposed topology was experimentally connected to the grid and the MLI was experimentally used as an active power filter to compensate for the harmonics generated due to nonlinear loads. This control technique was able to generating a sinusoidal grid current that was in phase with the grid voltage, and the grid current’s total harmonic distortion was within acceptable limits. To validate the practicability of the proposed MLI, both simulation and experimental results are presented.

Analysis of predictive control algorithm based PWM boost converter-based hybrid networks

The Power Electronic Converter (PEC) interfacing with the Renewable Energy Hybrid System (REHS) like solar, wind, etc is very much important and its implementations and validations are most required to reduce the harmonic distortions, unity power factor, DC-link voltage regulation, and lower frequency with high-speed operations. The PEC is like us three phase Pulse Width Modulation of Bidirectional Power Electronic Converter (BPEC). This paper proposes the novel Tracking Controller based Predictive (TCP) with PI controller is implemented and validated using dSpace TMS 1102 Digital Signal Processor in the VSC. This processor is used to generate the reference currents and a novel tracking controller based predictive Instantaneous Reference Current Generation using Synchronous Detection Method (IRCGSDM), based on this controller the real time data are sensed through current and voltage transducer from 1KVA inverter realized and software (MATLAB Simulink) simulations are validated through MATLAB Software, This novel TCP controller algorithm achieved a fast response in the DC-link voltage regulation, reactive power compensation with unity power factor and nearest sinusoidal grid currents using predetermination of cost function minimization.

Grid integration of three phase solar powered fault‐tolerant cascaded H‐bridge inverter

AbstractGrid integration of solar photovoltaic (PV) systems is becoming popular recently due to the merits of stable support to conventional grid, limiting global warming and reduced emissions. However, maintaining capacitor voltage balancing, unity power factor, sinusoidal grid current, and harmonic profile improvement are challenging tasks owing to change in irradiation conditions. Multilevel inverters (MLI) in grid‐connected systems will enhance the system's power quality in terms of voltage and current total harmonic distortion (THD). One of the most promising multilevel topologies for renewable energy applications is the cascaded H‐bridge (CHB) inverter. Since CHB inverters include many components, they have a higher risk of failure, lowering system reliability. Due to the change in irradiation condition, the voltage across the corresponding DC link capacitor may vary. Therefore, the DC‐link capacitor balancing is mandatory and done by an individual control scheme. This paper presents a highly reliable, robust, and modular solar PV‐fed fault‐tolerant CHB inverter with an individual voltage/current control strategy for grid integration. Higher reliability and modularity, power factor correction, and harmonic profile improvement are the main objectives of the proposed system. The proposed system has been simulated in MATLAB/Simulink and validated with experimental results on the developed prototype for different irradiation conditions.

Harmonic Distortion Minimization in Power System Using Differential Evolution Based Active Power Filters

Aims : The main focus in this work is to improve balanced and sinusoidal grid currents by feeding compensating current at point of common coupling (PCC). Background: In recent years the advancement in electronics and electrical appliances are widely improved and are also more sophisticated. These appliances require uninterrupted and quality power. Therefore in the growing power system scenario, several issues like malfunction of electrical sensitive devices, overheat in transformer, interference in communication, failures in computer network etc., adversely affects the power quality (PQ). These issues are generated due to rapid use of non-linear loads in three-phase system which generates harmonics in the system. To overcome from these PQ issues, several PQ mitigation custom power devices are integrated in power distribution network. But, the conventional PQ mitigation devices are insufficient to eliminate PQ problems such as current and voltage harmonics, voltage sag/swell and voltage unbalances associated with the power distribution network. Objective : The objective of using A-PSO is to find the global optimum of the spread factor parameter at the upper level. APSO, has a faster convergence speed and correct response compared to the PSO algorithm. Method : SO A-PSO M p-q. Result: A-PSO is giving better results than PSO. Conclusion : A three-phase system with SHAPF injected at PCC is proposed in this paper. The SHAPF injects filter current at PCC for supressing the harmonics using a modified pq scheme. For controlling the PIC, two optimised parameters are discussed and found that reducing the harmonics distortions using A-PSO is giving better results compare to the conventional PSO.

A grid-connected single-stage closed-loop controlled five-level boosting inverter for solar PV systems

ABSTRACT Multilevel inverters (MLIs) have gotten a lot of attention recently in the power industry because of their efficiency. The application of MLI in photovoltaic (PV) systems to improve power quality and performance has grown dramatically. An innovative, low-component-count 5-L boosting inverter interfaces a single-stage grid-tied PV system with a closed-loop control method in this research. The proposed MLI is put to the test using a 2.1 kW PV system. This technique guarantees optimum power monitoring, DC link voltage balancing, appropriate MLI operation and injection of clean sinusoidal grid current. The suggested system’s outcome is tested by Matlab/Simulink.

Single-Phase PFC Rectifier With Integrated Flying Capacitor Power Pulsation Buffer

Single-phase Power Factor Correction (PFC) rectifiers with sinusoidal grid currents are inherently subject to an input power fluctuating at twice the mains frequency. In order to potentially mitigate bulky, heavy and failure-prone electrolytic dc-link capacitors, active Power Pulsation Buffer (PPB) concepts are proposed in the literature. For converter systems employing Flying Capacitor (FC) multilevel bridge-legs, the FCs can be utilized as a twice-mains frequency energy storage, i.e., as an integrated active PPB without the need for additional power components. Such ac-dc-stage-integrated FC PPBs capable of buffering the complete input power variation are known in literature which, however, require sophisticated control strategies with varying switching frequency and discontinuous conduction mode. This paper presents a novel ac-dc-stage-integrated FC-PPB approach which is compatible with standard PFC control concepts and enables a significant reduction in dc-link voltage variation. First, a control concept cycling the FC voltage in a wide range without interfering with the grid current controller is derived step by step and verified by means of circuit simulations. Design guidelines for the calculation of suitable FC capacitance values are presented and the limits in buffering capability are discussed. The concept is then experimentally verified with a 2.2kW three-level FC single-phase PFC rectifier employing 600V GaN power semiconductors where the dc-link voltage variation is reduced by 28% compared to conventional operation. Last, the applicability of the ac-dc-stage-integrated FC-PPB concept to other FC converter topologies is discussed.

From MPC-Based to End-to-End (E2E) Learning-Based Control Policy for Grid-Tied 3L-NPC Transformerless Inverter

This paper proposes an end-to-end (E2E) learning-based control policy to directly control a transformerless grid-tied three-level neutral-point-clamped (3L-NPC) inverter powered by a photovoltaic (PV) array. This E2E control policy is represented by an artificial neural network (ANN) and a time-delay neural network (TDNN), namely, ANN- and TDNN-based control policies, to properly estimate the optimal switching vector of the 3L-NPC. With such learning-based control policy, there exists no need for deriving or understanding deeply the complex mathematical model of the 3L-NPC, as the dynamics of both the system and the control scheme, as well as the cost function to be minimized, are learned via an end-to-end learning fashion that maps directly from the raw observations to the optimal switching states. This definitely eliminates the major barriers of the model-based control strategies (i.e., model predictive control (MPC)) such as (i) the need for an accurate system model, and (ii) the exponential increase in computational complexity. In order to train the two control policies, the conventional MPC is employed, as an expert, for acquiring a set of training data (i.e., input-output pairs) and, thereafter, for assessing our proposed control schemes. The proposed E2E control strategies are validated using MATLAB/Simulink software, where the impact of having different input features and training data are studied. With the proposed control policies, especially the TDNN-based control policy that has only one time-delay window, a high-quality sinusoidal grid current is achieved with low total harmonic distortion (THD), resulting in enhancing the power quality of the utility grid. In addition, the leakage current is minimized compared to the conventional MPC by more than 25%. However, the same dynamic behavior is almost obtained during the irradiation changes compared to the MPC strategy. Moreover, the experimental verification of the proposed E2E control strategy is implemented on the basis of the Hardware-in-the-Loop (HIL) real-time simulator using the C2000TM-microcontroller-LaunchPadXL TMS320F28379D kit, demonstrating the applicability and good performance of our proposed control strategy under realistic conditions.

Adjoint least mean square control for solar photovoltaic array grid‐connected energy generating system

This study deals with a new control for a double-stage grid-integrated solar photovoltaic array (SPVA)-based energy generation system, which is based on adjoint least mean square (ALMS) control. This ALMS control algorithm has some new features: (1) it provides a fast rate of convergence, (2) harmonics mitigation ability, and (3) ease of implementation. The solar PV energy generating system includes a DC–DC boost converter, a voltage source converter (VSC), a ripple filter, a three-phase grid, and local non-linear loads. The VSC is controlled for feeding the active power from the solar array to the grid and three-phase non-linear loads. Moreover, VSC control is used to improve the grid current quality. A DC–DC boost converter is coupled between the photovoltaic array and the DC-link capacitor, which tracks the maximum SPVA power from the SPV array by using perturb & observe algorithm. Here, the main goals of SPVA generating system are to eradicate power quality problems caused by unbalanced and non-linear loads and to provide sinusoidal grid currents at solar PV array irradiance variation. Moreover, a comparison of ALMS control is made with other control algorithms. Performance of this ALMS control is studied at varying non-linear loads and under different environmental conditions on a developed prototype in the laboratory. The simulated results of the system are validated with test results. Detailed behaviour of the grid-integrated SPV system and harmonics spectrum of grid currents are given here while meeting the IEEE 519 Standard.