Selecting Optimum Stage Switching Interval for Capacitor Unit as Way to Increase Efficiency of Reactive Power Regulation

The paper describes the results of the study of an optimum interval for switching the stages of the capacitor unit (CU), which can improve the efficiency of automatic control of reactive power, reduce the wear and tear of the switching equipment and capacitors and prolong their service life period. The urgency of the research is determined by the lack of well-founded recommendations on the selection of the optimum switching interval for the CU stages. The recommendations on the selection of the optimum switching interval for CU stages are developed on the basis of the numerical simulation method using real reactive power curves of consumers and the Lab+ software program modelling the reactive power regulator. The optimum interval for switching capacitor banks, indicated in the settings of the automatic reactive power controller, is determined in relation to the reactive load conditions. For medium and abruptly variable reactive loads, it is very important to accurately monitor the load changes and control the reactive power generation at the maximum frequency, i.e., to use a minimum switching interval for the CU stages, which is to be no less than 120 seconds. For weakly variable loads, setting a minimum control interval does not lead to a significant reduction in the reactive power flow, and even increases the power flow in some cases. Therefore, prolonged switching intervals of 8, 15, 30 minutes are the most efficient and cost-effective for loads that do not significantly vary over time. The results obtained can help to improve the efficiency of automatic control of CU reactive power.