Day-Ahead Scheduling of On-Load Tap Changer Transformer and Switched Capacitors by Multi-Pareto Optimality

Abstract

In this study, a multi-objective optimization method is proposed to solve day-ahead voltage control problems in distribution systems. The main purpose is to determine the optimal schedule for on-load tap changer (OLTC) settings at the sub-station and switched capacitors (SC) based on day-ahead load forecasting. The optimization criteria presented in this study include: (1) minimizing the voltage deviations at the main transformer bus, and (2) minimizing the total power loss. In the proposed method, the Pareto front and Manhattan distance are combined as indices to assess and select the best solution. Multi-Pareto optimality is used to improve the performance of the proposed scheduling strategy. In this study, the network components were modeled by the DIgSILENT Power Factory 15.2, while the multi-objective optimization algorithm was implemented on the MATLAB 2016a software package. Additionally, the effects of different distributed generation (DG) grid-connected points and operation scenarios on voltage control scheduling were examined. The efficiency and performance of the proposed method were verified using an IEEE 33 BUS test system. Compared with the local voltage level (LVL) and reactive power device control (RPDC) methods, the proposed method delivered percentage reductions in (1) voltage deviations at all buses, (2) voltage variations, (3) total system power loss, and (4) difference in values of up to 160.93%, 31.16%, 10.35%, and 434.34%, respectively.