Enhancing Renewable Energy Hosting Capacity in Unbalanced Microgrids via Empowering Smart Inverters

Abstract

The rapid growth of photovoltaic (PV) generation, wind energy and plug-in electric vehicle (PEV) charging creates voltage unbalance, feeder congestion and power losses that limit the hosting capacity (HC) of renewable energy sources in practical unbalanced microgrids. A recent study coordinated PV systems and energy storage systems (ESSs) with smart-inverter functions on the unbalanced IEEE 123-bus microgrid using the Multi-Objective Grey Wolf Optimizer (MOGWO). This paper extends that work with a Multi-Objective Hippopotamus Optimizer (MOHO) and compares it with MOGWO. The microgrid is divided into six zones and includes a 1.5 MW wind generator and a 2 MW PEV load. PV inverters operate in combined voltvar/volt-watt mode, and a two-stage MATLAB– OpenDSS co-simulation minimises voltage unbalance and feeder overloading while maximising PV penetration. With an equal budget of 2440 power-flow evaluations over ten runs, the best MOHO plan reaches 215.9 % PV penetration against 184.5 % for MOGWO, reduces average voltage unbalance by 12.3 % (MOGWO 15.7 %), lowers the critical feeder peak loading from 175 % to 150 %, and cuts daily grid import by 43.9 % (MOGWO 43.0 %). MOHO raises reverse-flow losses and shows larger run-to-run variability, and the difference in mean performance is not statistically significant, so it is a competitive alternative for hosting-capacity planning.