针对电网存在的500 kV网络传输容量不足问题,提出一种机组降压运行方案的多阶段优选方法.首先,根据机组电压等级和机组容量与负荷的匹配度确定降压机组方案的候选集合;然后,选取系统网损、线路潮流过载率、电压偏移率、静态电压稳定裕度、静态灵敏度和短路电流作为机组降压运行方案的评价指标,并构建线性加权的优化模型,采用变异系数法计算优化模型的权重,根据优化结果对待选降压方案进行综合排序;最后,对降压运行方案进行N-1校核和稳定性计算,综合分析各个方案对电网的安全稳定性影响,最终优选出降压运行方案.以某电网为例,结果表明所提方法能够有效缓解500 kV网络输电阻塞问题,降低网络损耗、优化网络架构.%Aiming at the insufficient transmission capacity of 500 kV power grid,a method of multi-stage optimization is proposed for the voltage-reduced unit operation.The candidate sets are determined according to the voltage level of units and the matching degree between unit and load.The network loss,line overload rate,voltage deviation rate,static voltage margin,static sensitivity and short circuit current are selected as the evaluation indexes and a linearly-weighted optimization model is built.The variation coefficient method is adopted to calculate the weights of the model and the candidate voltage reduction schemes are comprehensively ranked according to the optimization results.N-1 verification and stability calculation are carried out for the schemes of voltage-reduced operation,the influence on the safety and stability of power grid is analyzed for each scheme,and the optimal one is finally chosen.With a power grid as an example,results show that,the proposed method can effectively alleviate the transmission congestion of 500 kV power grid,reduce the network loss and optimize the network structure.
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