Research on Reactive Power Optimization of Long Distance Ultra-high Voltage Cable Connected to Municipal Power Grid

摘要

Because the charging power of cables is far higher than that of overhead line, the connection of long-distance ultra-high voltage cable to the urban power grid will seriously affect the voltage level of the regional bus, increase short-circuit current, and even endanger the safe and stable operation of the system. In this paper, aiming at the capacitive reactive power excess caused by ultra-high voltage cables, and with the regional bus voltage reduction and active power network loss reduction as the optimization objective, the optimal input capacity of each node with high reactance is obtained based on particle swarm optimization algorithm. Based on the PSASP program and the actual power grid model, a decision function based on the power grid voltage level is introduced according to the actual situation of the project. Besides, the optimal compensation scheme is given for reactive power, and the variation of regional power flow before and after high resistance compensation is explored. According to the research results, after using the high resistance compensation scheme proposed in the paper, the maximum voltage reduction of the relevant nodes before and after compensation reaches 1.71%. Considering the compensation method combining high and low voltage reactors, two groups of low resistance are successively put in, and it is found that the maximum voltage reduction is increased from 2.23% to 2.45%. Compared with other high-resistance compensation schemes, the node-voltage adjustment margin with the highest regional voltage increases from 0% to 1.35%, being better than 0.92% and 1.04%. Besides, relatively to the other schemes, the active power network loss of the line drops by 0.16MW. It is proved that the proposed method can help to improve regional voltage level and reduce active power network loss.