Nonlinear loads in islanded microgrids often drive the total harmonic distortion (THD) of grid-forming inverter output voltage above 5%, exceeding IEEE Std 519-2014 limits. To address this challenge, we propose a control strategy for three-phase four-wire inverters to ensure robust power quality. We model the inverter’s output impedance to analyze harmonic behavior and develop a phase-compensated resonant controller (PCRC) to suppress harmonics at the nominal frequency. However, PCRC’s narrow bandwidth struggles with frequency deviations caused by droop control. To overcome this, we introduce a hybrid feedforward strategy, integrating wideband capacitor voltage feedforward with load current feedforward, modeled as a virtual impedance network. Compared with existing methods, our approach better sustains harmonic suppression during frequency shifts. Experimental results verify the effectiveness of the control strategy, demonstrating that the hybrid feedforward strategy significantly reduces the THD of the output voltage.

The single-phase differential boost inverter (SPDBI) possesses unique single-stage boost capability, which conventional voltage source inverters lack. While the discontinuous modulation strategy offers superior efficiency advantages, the inherent nonlinear distortion issues in SPDBI remain unresolved. This paper proposes a dual-loop control strategy based on pulse train control, which achieves excellent voltage tracking and dynamic performance through well-designed duty cycles for two pulse train sets. Simulation and experimental results validate the effectiveness of the proposed control strategy.

Compared with traditional inverters, the T -type three-phase three-port inverter can realize bi-directional power flow in three sources with a smaller size and lower cost. In this paper, a novel T -type three-phase four-leg (3P4L) three-port inverter with two DC ports and an AC port is proposed and its output vectors are analyzed. Correspondingly, the maximum power distribution range named maximum distribution ratio control (MDRC) between two DC ports is extended from the three-phase three-wire (3P3W) system to the three-phase four-wire (3P4W) system. A mathematically proven algorithm for simplifying the calculation of duty cycles and implementing MDRC is proposed. Finally, this paper selects a three-phase unbalanced linear load to verify the proposed power control strategy in MATLAB/Simulink.

Residential load models used for distribution network planning and power equipment design are based on statistical load data measured over long periods. Using historical data to determine future network expansion requirements has several shortcomings. Urbanization, lifestyle changes and communal habits shape the electricity demand profile. Shorter periods of peak loading result in higher maximum demands than distribution equipment is designed for leading to reduced equipment life cycles. Distribution planning methods based on historical data do not include provision for an embedded generation. The empirical load model developed in this research is based on actual domestic loads using time-of-use data. The load model is also to investigate the effect of embedded generation on the load profile. The outcome of this research is a novel method of compiling load profiles that can be used during the planning process of distribution grids serving predominantly townhouse complexes and other high-density residential clusters with embedded generation. The simulation results of the load model are validated and compared against the planning calculation method and measurement results of similar residential townhouse clusters.

This paper presents reformed electric system cascade analysis (RESCA) technique for optimization of hybrid renewable energy system (HRES) comprising of wind energy conversion system (WECS), photovoltaic (PV) system, battery energy storage system, and non-intermittent source (NIS). Optimization constraints of final excess energy, energy generation ratio, cost of energy, net present cost (NPC), and renewable energy fraction are considered for the optimization of the system. This optimization is realized for an isolated load comprising of the ten households in Malaysia with a daily consumption of 84.5 kWh. On successful implementation of RESCA with different constraints, it is found that the optimum size of energy sources for the HRES varies depending on the chosen constraints. Also, the NPC of the system can be considerably reduced on introduction of NIS to the HRES. RESCA provides the user with better insight into the influence of variation of PV and WECS power generation while identifying the optimal size of energy storage unit. The optimized results obtained are also compared with benchmark HOMER software to validate the methodology.

Due to the inherent intermittent nature of renewable energy sources (RES), the control and management of microgrids become complex and require modern control techniques and management strategies to cope up with the changes in the dynamics of the system. This paper focuses on improving the dynamic performance of a microgrid by developing different energy management and control strategies employing a four-layer multiagent concept. The first layer of the proposed system is a forecasting and estimation layer and is responsible for providing the real-time forecasts for RES output power, load, and battery state of charge. The second layer is a control and action layer, assigned with the duties of taking the control decisions and actions accordingly by collecting information from different agents deployed in the system. The third layer is a real-time monitoring and control layer that provides the real-time information of the microgrid to the second layer. The fourth layer is a fault detection and action layer that facilitates the self-healing capability in the proposed microgrid. The performance and the applicability of the proposed model is tested by simulating the faults at different locations in the system.