Tripping of inverter-based resources (IBRs) powered by renewables poses a key challenge for reliable grid integration, especially at point of common coupling (PCC). Intermittency of solar and wind leads to power fluctuations, causing dynamic variations in PCC voltage amplitude and phase. As a result, voltage parameters sensed by incoming sources become time-varying functions of real-time power exchange. During IBR synchronization, rapid power shifts may induce fictitious frequency deviations estimated by phase-locked loops (PLLs), triggering false tripping during phase angle jumps (PAJs). This article tackles such synchronization and tripping issues for a microgrid comprising a wind-driven doubly fed induction generator (DFIG), solar photovoltaic array, and battery energy storage. A multifunctional control enables seamless operation across grid-tied and off-grid modes, even with or without DFIG stator-PCC connection. A multiple delay signal cancellation (MDSC115) prefilter and enhanced PLL (αβ-EPLLVI) ensure robust synchronization are validated as per the IEEE Std. 1547 via simulation and hardware results.

Four-wire configurations are commonly used in residential microgrids, where single-phase and nonlinear loads introduce harmonics, third-harmonic currents, and negative-sequence components. These harmonics often circulate within delta loops formed by line conductors, while negative-sequence currents cause power imbalance. In wind energy-based microgrids with transformers, such harmonic and unbalanced currents are often reflected into transformer or grid, leading to overheating, increased losses, reduced active power transfer ability, and possible failure. Processing these harmonic currents through transformers to prevent grid contamination demands a higher-rated neutral conductor, adding cost and thermal stress. To address these challenges, this work proposes a three-phase four-wire topology with an auxiliary converter at load point of common coupling (PCC), supported by a solar photovoltaic (SPV) array and battery energy storage (BES). Four-leg auxiliary converter compensates for load harmonics, neutral currents, negative-sequence components, and reactive power, while enabling power exchange from SPV array and BES units. It operates in both grid-forming and grid-following modes to support seamless transitions between islanded and grid-connected states. Integrated multi-mode control ensures coordinated source operation and compliance with IEEE Std. 1547 during mode transitions. Simulation results validate system effectiveness across various modes, demonstrating substantial improvements in power quality and operational reliability in residential microgrids.

This study presents a hybrid power conversion system comprising a doubly fed induction generator (DFIG) based wind generator, solar photovoltaic array, and battery energy storage, and a diesel generator (DG) set, designed to shield DFIG from grid voltage abnormalities. Key contribution in this work is to ensure uninterrupted power delivery across six operating modes and ten transitions, enabling seamless dynamic performance. This work also ensures operating each renewable energy at maximum power point, regardless of operational modes or transitions. Sinusoidal currents are maintained for DG set, DFIG stator, and grid, even under nonlinear and unbalanced loads, meeting power quality standards. DG set operates within its optimal fuel utilization zone, enhancing efficiency, and reducing costs. Hardware validations in steady-state and dynamic conditions demonstrate stable operation, seamless transitions, and uninterrupted power supply in grid-tied andoff-grid scenarios. Maximum utilization of wind and solar energy is achieved, with DG set ensuring adequacy during prolongedoff-grid conditions. Results confirm compliance with power quality standards and seamless operation under various dynamic conditions.

Integration of renewable energy sources into standalone microgrids is gaining significant attention due to increasing demand for sustainable and reliable power systems. Solar photovoltaic power plant (SPVP) and synchronous diesel generators (DG) are commonly used in these configurations to ensure a stable and continuous power supply. Presence of SPVP reduces rating of DG set to be used. However, integration of these sources presents challenges related to power quality leading to reduced system power transfer capability and increased losses with reduced life of DG. Ensuring reactive power compensation, harmonics mitigation, and balanced load conditions are critical for optimizing performance of DG set and maintaining stable system operation. Hence, this study presents an advanced control strategy that leverages voltage source converter of SPVP to achieve unity power factor operation for DG set, while also compensating for harmonics and unbalanced loads. By employing an improved variable step normalized adaptive filter, presented control enhances system power quality following the IEEE standard 1547–2018. Simulations and hardware validations are conducted to verify effectiveness of control, demonstrating its potential to improve fuel efficiency and reduce operating costs in standalone microgrid applications.

Community and residential loads connected to low voltage AC distribution networks require a neutral point connection. Neutral point forms return path for single-phase loads. Presence of neutral wire reduces effect of unbalanced loading of one phase to get reflected on other load phases. It helps during fault conditions to minimize effect of circulating current by providing low impedance path. However, in case of harmonically polluted load currents, rating of neutral conductor increases, leading to additional losses and unwanted heating effecting other components of network. Wind energy conversion systems (WECS) use transformer for connection to AC network to reduce requirement of higher rating and size of DC link capacitor. Neutral current and harmonic currents of load are processed through the transformer, which leads to additional heating of transformer ands which is detrimental for connected loads. Such conditions can lead to failure of WECS operation and damage transformer and connected sensitive loads due to flow of circulating currents. Hence, this work presents design and control of a novel four wire topology of a WECS comprising of a doubly fed induction generator (DFIG) and a battery energy storage (BES). A grid forming converter (GFC) is deployed to provide independent compensation for load neutral and harmonic currents without affecting the WECS transformer, reducing its failure and heating rate. WECS converters are controlled to improve power quality of stator current and point of common coupling (PCC) voltage as per the IEEE 519-2022 std. Simulation results present MPPT operation of WECS with neutral and harmonic compensation even during dynamic conditions.

The nonlinear loads demean the system power quality leading to increased ohmic losses and shorter equipment lifespan. To mitigate power quality challenges, this work proposes a multiple delayed signal cancellation filter with 15 layers and unit delay factor (MDSC115) for improved power quality of a grid-tied solar power conversion system (SPCS) equipped with a battery energy storage (BES). The control attenuates all integral positive sequence harmonic components from 2ndto 30thharmonics excluding positive sequence 16thharmonic. It also eliminates integral negative sequence harmonic components from 1stto 28thharmonics excluding negative sequence 14th harmonic, including 0 Hz DC component, without the need of additional prefilters cascaded to the filter. A modified frequency locked loop (MFLL) is incorporated to make the MDSC115 adaptive to the varying grid frequency and make it immune to phase angle jump and frequency fluctuations in the grid voltages. The MDSC115-MFLL improves the power quality of SPCS during grid adversities and load current irregularities. Performance of MDSC115-MFLL is validated in MATLAB during several dynamic test cases and compared with other delay-based controls to ensure better performance and commitment to the IEEE std. 519 during operation of SPCS.