Enhancing microgrid performance: Optimal proactive reactive power dispatch using photovoltaic active power forecasts

Abstract

Microgrids with substantial incorporation of distributed renewable energy sources face challenges such as magnitude voltage rise, frequency variations, and power quality issues. A novel method is proposed to managing and controlling reactive power within microgrids with high integration of photovoltaic panels. The proactive dispatch is carried out for a few minutes in advance, using power forecast and the inverters of the photovoltaic installations as reactive energy providers. The goal is to stabilise voltage levels and reduce overall energy losses. Optimising reactive power poses a non-convex problem. The presented method tackles this challenge by employing Conic approximations and Wirtinger calculus techniques to convert and frame the issue within a convex framework, simplifying its resolution. It primarily concentrates on fine-tuning reactive power output from photovoltaic inverters to minimise overall losses and maintain stable magnitude voltage levels. To enable the reactive power dispatch, a Markov switching forecasting model that uses on-site data, including sky imagery and other external variables, predicting active power generation every 6 minutes. The proposed technique is evaluated in a CIGRE test network, showing an average loss reduction between 14% and 66% for sunny and cloudy conditions with different levels of PV penetration, this while maintaining the steady state voltages in range.