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This paper presents an experimental validation of, phase-lock loop less modified control strategy for single-phase shunt active power filter (APF) to compensate current harmonics and reactive power in single-phase distribution system under distorted supply voltage. The control technique is divided into two parts: first associated with selected frequency signal extraction by using Hilbert transform-based adaptive tuned filter from distorted supply voltage followed by reference current signal generation using DC-link energy balance method. Second deals with an improved pulse width modulation technique which reduces switching ripple and switching frequency for voltage source inverter used as a shunt APF. The overall control scheme is simulated using MATLAB/Simulink environment in the steady state and transient condition of the load. A detailed hardware design and other parameters of proposed system have been presented. A laboratory prototype has been developed using dSPACE DS1104 controller card having TMS320F240 as a slave DSP to verify the simulation results. Simulated and experimental results show that the proposed control technique gives a flexible and fast dynamic response in single-phase distribution system. The harmonic spectral performance of the proposed technique is as per the recommendation of IEEE-519 standards. [ABSTRACT FROM AUTHOR]

• An adaptive VSSAPS control algorithm for reference current generation is designed. • A multifunctional 3-phase inverter for a grid-interfaced solar PV system is examined. • The VSSAPS controller efficiently complies grid-connected IEEE Std 519-2014 and Std 1547-2003. • Control strategy validated utilizing dSPACE 1104 RTI control board. This article proposes a variable-step-size Affine Projection Sign algorithm that improves power quality ancillary services in a grid-interactive solar photovoltaic system. VSS-APS algorithm features decreased steady-state fluctuation, faster convergence, and robustness to disturbances. The VSS-APS algorithm efficiently extracts contaminated source current active and non-active fundamental weight components to estimate source current reference signals. The solar grid-integrated voltage source inverter manages solar PV unit active power and provides free multipurpose PQ-ancillary services. Harmonic current, active power, load, neutral current, reactive power, and power factor correction are the PQ indices that improved significantly with the proposed VSS-APS control. VSS-APS improves GISVSI's steady-state and dynamic performance. MATLAB®/SIMULINK and a scaled laboratory prototype developed to test the VSS-APS control approach. The DSP-dSPACE 1104 controller implements the suggested controller in real time. The proposed VSS-APS control algorithm is compared with the conventional algorithms, and test results from a laboratory experiment demonstrate its feasibility and benefits. The experimental results show that the proposed VSS-APS algorithm is effective in improving power quality while complying to IEEE 519-2014 and IEEE 1547-2003 standards for grid connections. [ABSTRACT FROM AUTHOR]

Summary: This paper presents an active current detection method (ACDM) for three‐phase grid‐tied solar photovoltaic (PV) system. The proposed control utilizes the character triangular function (CTF) for fundamental component extraction and minimizes the computational burden. This shows the effectiveness of proposed ACDM under variety of operating conditions. Moreover, the design of control algorithm allows superior voltage regulation in outer voltage control loop, which reduces the peak overshoot during transients. This will also help in regulating grid current quickly, and it accurately follows the reference current. Further, the proposed control algorithm effectively deals with several power quality (PQ) issues and maintains the continuous power flow to satisfy the load demand. Finally, the withstand capability of the proposed ACDM controller is verified by simulation studies under MATLAB®/Simulink environment and experimentally validated by dSPACE‐1104 based downscaled laboratory prototype. [ABSTRACT FROM AUTHOR]

This study aims to propose optimised and robust current controller for the transformerless grid‐integrated photovoltaic inverter. Challenge of ensuring improved power quality while minimising the DC‐component under non‐ideal grid condition is at the forefront in the photovoltaic system. In this context, an advanced current controller is designed and developed in the stationary reference frame with proportional‐integral (PI) plus four‐vector PI (4VPI) controllers. The PI‐controller modulates the shape of fundamental current to follow its reference induced from outer DC‐link loop. Meanwhile, 4VPI controllers are tuned at the multiple of grid frequencies including third‐(3ω0), fifth‐(5ω0), seventh‐(7ω0), and ninth‐(9ω0) to introduce infinite gain and thereby alleviating stationary errors in the current loop of the photovoltaic inverter. The most distinguishing feature of the proposed controller is its inherent control robustness, and therefore, it operates satisfactorily against control delay time and frequency excursion. Traditionally, cumbersome trial‐and‐error techniques have been largely employed to adjust the PI‐VPI controller gains. Nonetheless, tuning of these parameters has made many practitioners switch‐off from employing the proposed controller. Given this, the particle swarm optimisation algorithm is proposed. Finally, the practicality of the proposed controller is verified through comprehensive set of simulation and experimental tests conducted on a laboratory‐developed prototype using dSPACE‐1104. [ABSTRACT FROM AUTHOR]

In this paper, modelling and hardware implementation of three-phase interleaved inverter-based shunt active power filter (SAPF) is proposed to mitigate current harmonics, reactive power for ensuring unity power factor and load balancing without shoot-through effect. Shoot-through effect is one of the hazardous issues in conventional voltage source inverters such as damage of power electronic switches, electromagnetic interference, ringing in the power circuitry. The present power system has inevitable non-linear loads which create large variations in the supply voltage distortions. Therefore, the compensation capability and efficiency of the SAPFs degrades. A novel predictive tuned filter is proposed in this paper to estimate the variations in the amplitude of supply voltage, frequency and harmonics for extracting the fundamental voltage signal. The fundamental extracted signal is further processed for reference current generation using generalized p-q theory. The performance of the proposed system is simulated using MATLAB®/Simulink environment and tested under different supply voltage conditions. The simulation results have been validated by developing a prototype in the laboratory by using a dSPACE1104 controller. It is found from the simulated and experimental results that the proposed system is fast, robust and accurate which improves the power quality without shoot-through problem. [ABSTRACT FROM AUTHOR]

In this study, harmonics related to power quality issue and energy demand growth are considered simultaneously towards the realistic planning of medium voltage radial distribution system. Mostly, harmonics of distribution networks are produced in the presence of non-linear loads. Therefore, Distributed Energy Resource (DERs) can be placed to mitigate the harmonic distortions and to supply the required system energy demand. This paper presents a Modified Group experience of Teaching Learning Based Optimization approach, which can deal with allocation of DERs efficaciously in distorted and non-distorted radial distribution networks. The effectiveness of the proposed approach is validated on standards 33-bus and 69-bus test systems along with 83-bus (Taiwan Power Company) practical radial non-distorted distribution system. The results are compared with already well-established existing methods as suggested in the literature. Further, the proposed algorithm is applied to DER planning considering harmonics generating loads in above-mentioned test systems. The results with linear as well as non-linear loads on all three test systems prove that the proposed strategy can be a robust approach to enhance the system performance towards mitigating increased load demand within the constraints of the distribution system. [ABSTRACT FROM AUTHOR]

This article presents a modified fuzzy controller (MFC) to generate a reference signal for the control algorithm to drive the shunt active power filter (SAPF) for improving the power quality of a microgrid at the distribution end. The proposed MFC, based on the alive-and-kicking behavior of the system, is used to regulate the DC-link voltage of the SAPF. The MFC is implemented through the general dynamic behavior of a process with introducing the new rules set. It is compared with the PI controller for evaluation of optimal steady-state, dynamic, and transient performance of SAPF, namely the reactive power and DC voltage control. The effectiveness of the proposed controller is tested on non-linear loads using a hardware prototype. The STM32F407VGT (ARM Ltd., San Jose, California, USA) processor is used to interface algorithm with the hardware setup. The results of the proposed controller scheme are promising and are compared with MATLAB (The MathWorks, Natick, Massachusetts, USA) simulation results. The system is capable for minimizing current harmonics, reactive power and improving the power factor. Also, the advantage of the STM32F407VGT over the Digital Signal Processor (Texas Instruments, USA) is introduced. The performance of the proposed controller is better in comparison with conventional controller. [ABSTRACT FROM AUTHOR]

Shunt active power filters are the most viable solution for solving current harmonic, reactive power compensation, and load unbalancing problems widely presented in electrical distribution systems. In this article, development and implementation of a digital signal processor based three-phase four-wire shunt active power filter are analyzed to compensate non-linear and unbalanced loads under non-ideal supply voltages conditions. The proposed algorithm is divided into two parts, the first associated with the calculation of the positive-sequence component of unbalanced supply voltage and second deriving a simple and attractive fundamental extraction filter to extract the fundamental frequency component from distorted positive-sequence voltage. Average power and DC-link energy balance methods are used to calculate peak value of the supply current, which is required to flow from source to load. The behavior and effectiveness of the proposed control algorithm has been verified by simulation using MATLAB/Simulink (The MathWorks, Natick, Massachusetts, USA) environment for different cases of supply voltage. A laboratory prototype has been developed to verify the simulation results. The control scheme is realized using a TMS320F28335 floating-point digital signal processor (Texas Instruments, Dallas, Texas, USA) based system. It is found that simulated and experimental harmonic spectral performances are in compliance with the recommendations about harmonic limits imposed by the IEEE-519 Standard. [ABSTRACT FROM AUTHOR]

This paper presents a novel Digital Signal Processor (DSP) based control algorithm for 3-phase shunt active power filter (APF) using neural network and indirect current control strategy to eliminate current harmonics and reactive power compensation under ideal and distorted supply voltage. The compensation process is based on sensing of source current instead of filter current, and thus differs from conventional techniques for elimination of switching ripples. Fundamental frequency signal extraction is done using adaptive linear neuron (ADALINE) network from distorted voltage signal without using low-pass filter or phase-locked-loop block. ADALINE gives simple, robust and accurate design for selected frequency extraction. Instead of calculating oscillating and reactive power, the reference generation is used to calculate average active power component. Various simulation results are presented to study the performance of proposed design during steady-state and transient conditions of non-linear loads using MATLAB/ Simulink tool under sinusoidal and distorted supply voltage conditions. Simulated response has been validated with a laboratory prototype using a Texas make floating-point TMS320F28335 DSP. Based on the simulated and experimental results it can be concluded that the spectral performance of the input current are in compliance with the harmonic limits imposed by IEEE-519 standard. [ABSTRACT FROM AUTHOR]

Summary: Multilevel inverter based shunt active power filter is cost‐effective and decisive solution for mitigating numerous power quality problems in case of medium‐voltage distribution sector. Performance of the filtering unit and nature of source current mainly depends on current control loop of control algorithm. Conventionally, proportional‐integral controllers are used in current control loop for AC current controllability, but it suffers from severe problems, namely, magnitude and phase error in steady‐state conditions. This paper presents an advanced current control loop that consists of a new breed of compensator called proportional‐resonant compensator for cascaded H‐bridge multilevel inverter based shunt active power filter in order to maintain zero steady‐state current error. Stability of proposed current control loop and closed‐loop control mechanism is extensively checked and analyzed using transfer function approach and root‐locus criteria. A complete mathematical analysis of the proposed control system has been presented, and parameters of proportional‐resonant regulator are finely tuned using bode plot technique. The performance of proposed control mechanism is tested using MATLAB/Simulink. A detailed experimental analysis has been carried out to verify effectiveness of the proposed controller over conventional one. Source current waveform becomes sinusoidal, and harmonic limits are in compliance with IEEE‐519 standard after successful operation of filtering unit. [ABSTRACT FROM AUTHOR]

Summary: This paper presents design and hardware implementation of single‐phase interleaved inverter as shunt active power filter (SAPF) to mitigate shoot‐through phenomena and power quality problems like current harmonics and reactive power compensation. Shoot‐through phenomena are 1 of the failure mode in conventional voltage source inverter (VSI) which may damage power switches. This also introduces ringing effect and temperature rise and affects the reliability and efficiency of the system. However, external dead band circuits are used to eliminate these problems, but they reduce the harmonic compensation level. Further, the multitudinal sliding mode controller (MSMC) is proposed for stabilizing the DC‐link voltage under steady‐state and transient condition of the load. This has shown an excellent tracking capability with reduced DC‐link voltage ripples compared to the conventional sliding mode and PI controllers. DC‐link energy balance theorem is used for reference current generation. The proposed topology has been modeled using MATLAB®/Simulink environment and tested under the steady and transient condition of the load in different supply voltage conditions. A laboratory prototype has been designed and developed using dSPACE 1104 controller to validate the simulation results. The test results show the viability of the control algorithm and performance of the proposed interleaved inverter in the power quality applications. [ABSTRACT FROM AUTHOR]

The voltage sourced-inverter (VSI) interfaced photovoltaic (PV) system with classic controller supplies the true power demand of the loads coupled at the Point of Interconnection (PoI). Thus, PV systems assets practically remain dormant at nighttime which reduces the device utilization factor of the VSI. Therefore, to subjugate the underutilization of VSI, this paper presents a synchronously rotating dq-frame and adaptive phase-locked loop (PLL) structure. The proposed system serves the following distinctive functions: (i) True power management function which is fundamentally responsible for sharing power requirement of the nonlinear load based on the renewable power accessibility at DC-link; and (ii) Active harmonic filtering (AHF) which is responsible for deliberately producing controlled harmonics in the output current and, in turn confronting the power quality (PQ) challenges. The envisaged control structure can be purposefully employed to transfer the power into the electric grid while providing grid current harmonic mitigation and balancing, reactive power elimination, and unity power factor (UPF) operation. In this respect, it is an inexpensive substitute to existing commercial shunt AHF meant for this job. The most distinctive feature of the presented structure is its computational effectiveness and easy implementation. Furthermore, insights are provided on the operating principle of a DC-link voltage control loop and power balance operation. The proposed PV system employs an incremental conductance (InC)-based technique to ensure optimal power evacuation from the PV arrays. Finally, the MATLAB/Simulink simulation and dSPACE-1104 based experimental results confirm the potential merits of the proposed structure to restrict the grid current distortions within the 5% and thereby complying with THD limit specified in the IEEE-519. [ABSTRACT FROM AUTHOR]

The increasing prevalence of photovoltaic (PV)-wind-battery-based microgrids and their integration into distribution networks have brought new challenges in grid ancillary services, such as poor power quality (PQ), grid instability, voltage and current fluctuations, and low efficiency of microgrids. These adverse effects are due to the intermittent nature of PV and wind power generation. The present work proposes an adaptive dynamic power management (ADPM) approach and enhanced instantaneous symmetrical component theory (EISCT) to improve the microgrid operation and grid ancillary services. The proposed ADPM-based EISCT not only utilizes a single grid side converter (GSC) but also reduces the sensor requirement and control structure complexity and thereby eliminates communication mismatch. The control structure, proposed in this research, has two major segments. The first segment focuses on active power management control through ADPM to facilitate efficient power flow between the utility grid and microgrid sources which helps in ensuring efficient power sharing. The second component is dedicated to synchronizing the renewable energy sources of the microgrid with the utility grid and simultaneously maintaining PQ compliance as per IEEE 519–2022 standards. The efficacy and adaptability of the proposed structure are validated through MATLAB®/Simulink® environment and the practical superiority of the system has been tested by using MicroLabBox® DS1202-based real-time hardware set-up. The experimental result shows improved performance of the developed structure under various microgrid operating conditions including dynamic loading situations, and battery system state-of-charge (SOC). The simulation and experimental results suggested that the DC-link ripples have been reduced to 2%, peak overshoot to 1.8%, settling time during the transition to 1.2s, battery response time to 0.3s, and the total harmonic distortion (THD) to less than 5%. These results demonstrated the superiority of the ADPM-based EISCT over conventional strategies. [ABSTRACT FROM AUTHOR]

• Presents an HFAO filter for improving mode transfer ability in microgrid operation. • HFAO filter accurately tracks harmonic frequency signal under distorted grid condition. • Improved performance under intermittent renewable energy generation. • A comparative analysis is included to validate superior filtering capability. This article proposes a multifunctional control scheme to enhance the mode adaptive capability that prevents the collapse of microgrids subsequent to the failure of the utility grid and power generation units. The proposed control scheme allows photovoltaic, wind, and battery energy storage-based microgrids to operate impeccably during grid-connected and islanding modes. Static transfer switches are used to isolate and relink the microgrid to the utility on occurrence and clearing of faults. However, due to the presence of harmonics of variable frequencies in the utility grid, the mode transfer fails using conventional schemes. To the contrary, a novel harmonic frequency adaptive observer (HFAO) filter is proposed in this paper for accurate tracking of harmonic frequencies to exact fundamental components of signals under inadequate grid and nonlinear load conditions. The HFAO calculates frequencies and magnitudes of harmonics present in the signal accurately with reduced ripples, increases the robustness of quadrature-phase signal to sub-harmonics, and improves harmonic rejection property. All conceivable implications of the proposed controller are investigated under various conditions of load and microgrid operating modes using MATLAB®/Simulink® environment. Results from in-silico experiments confirm that compared to conventional control schemes, the proposed controller is more accurate in tracking harmonic frequency signals with respect to changes in grid distortions and loads. [ABSTRACT FROM AUTHOR]

• The effect of PLL dynamics and instability when the GSC of the microgrid is integrated into the weak grid is thoroughly investigated with bode plots. • An enhanced feedforward controller for microgrid systems to improve the grid synchronization ability, enhance its power injection/absorption capabilities. • An output impedance model is designed to reduce the negative impedance range of the PLL. • A complete stability of the system using proposed controller has been analyzed with detailed bode plots while considering the PLL dynamics under weak utility grid. This article revisits the design of a feedforward controller to improve the stability of grid side converter (GSC) in a microgrid system with harmonic reinjection ability, and power transfer capability while integrating into a weak utility grid. The stability and injection/absorption of active power to the utility grid are greatly affected by grid conditions. In addition, the variable grid impedances because of the expanding utilization of renewable energy sources, long distance of transmission lines, power system faults, harmonic pollution, etc., interrupts the grid codes. In these uncertain grid circumstances, coupling between the phase-locked loop (PLL) of the d -q control scheme and the grid impedance might also lead to instability. An enhanced feedforward controller term is implemented during the proposed research to counteract this effect. The proposed controller adapts the changes in grid parameters and makes the system stable by increasing power transfer to the receiving end. Proficiency of the proposed control scheme is validated by comparing it with existing control schemes using simulation tools with different operating modes of the microgrid and weak grid conditions. It is established from the simulation results that the proposed novel feedforward controller gives substantiated results during stable operations and integration while maintaining the IEEE-1204 standards. [ABSTRACT FROM AUTHOR]

• Step by step designing of grid connected PV system. • Proportional resonant controller-based strategy is proposed. • The proposed system is implemented through cost effective microcontroller. • The developed prototype is tested for various operating scenarios. This research article presents a detailed documentation regarding test-bench development of Grid Interfaced Solar Photovoltaic (GIPV) system. The proposed GIPV system is developed using Voltage Source Converter (VSC) and DC-DC boost converter. The GIPV test-bench is developed using various auxiliary circuits including voltage/current measuring circuit, signal conditioning circuit, phase-shifting circuit, complementary pulse generation circuit, and driver circuit etc. These auxiliary circuits are designed in express printed circuit board software and fabricated in laboratory to develop a complete GIPV system test-bench. A combination of modified Synchronous Reference Frame (SRF) scheme and Proportional Resonant (PR) controller is proposed for current reference generation. Amplitude adaptivity based SRF-Phase Locked Loop (SRF-PLL) is presented to precisely detect the phase-angle of grid voltage under distorted and unbalanced conditions. The prototype is implemented using a commercially cheap ARM Cortex-M4 based STM32F407VGT6 microcontroller. This microcontroller has diversified peripherals for flexible target set-up with faster computation capability and a sophisticated user interface having TCP/IP connectivity. The control structure is developed in waijung environment for automatic code generation. The effectiveness of the proposed control algorithm is tested by numerical simulations in MATLAB/Simulink. Finally, practicality of the proposed GIPV system is experimentally demonstrated using ARM based microcontroller under various operating conditions. [Display omitted]. [ABSTRACT FROM AUTHOR]