To address the issues of low renewable energy penetration and poor power quality in traditional source-network-load-storage (SNLS) systems

an optimum control scheme for an SNLS system embedded with a unified power quality conditioner (UPQC) is presented. The proposed scheme is implemented using the particle swarm optimization (PSO) based extreme learning machine (ELM) algorithm. In the multi-objective optimization operation scheme: the first optimization objective is to maximize the power generation of photovoltaic (PV) arrays; the second and third optimization objectives are to minimize the load voltage deviation and maximize the network side power factor

respectively; and the fourth optimization objective is to maximize the utilization rate of the converter. Since the multi-objective optimization problems are difficult to solve in real-time

a hierarchical optimization approach based on the priority order of optimization objectives is presented to simplify the multi-objective optimization problem into several single-objective ones. Then

by training all the optimum solution sets obtained as an PSO-ELM surrogate model

the proposed strategy can be executed quickly and accurately. Finally

the effectiveness of the proposed scheme is verified through simulations. The case studies show that the proposed strategy can improve the absorption rate of renewable energy and the utilization rate of converters

and optimize power quality.