考虑配电网络的负荷聚合方法

Aggregation Method of Loads with Distribution Network Considered

负荷模型对电力系统仿真与控制具有突出影响。针对传统负荷聚合方法只能考虑同一母线下静态负荷、感应电动机负荷聚合的不足,提出了一种考虑配电网络的负荷聚合方法。该方法首先根据配电网络的节点电压方程消去联络节点,只保留负荷节点;根据聚合前后配网有功、无功损耗相等的原则,由保留负荷节点电压与简化后的网络导纳求出等值配网阻抗。再由等值配网阻抗与供电点的电压与注入电流求出虚拟母线电压。然后将负荷移置到虚拟母线上。最后根据电动机的机电模型,将虚拟母线上的电动机负荷聚合为一台电动机负荷;静态负荷聚合为一个综合静态负荷。由于考虑了配网阻抗的影响,聚合模型较好地保存了配网的综合负荷模型特性。有功、无功拟合误差较小。算例表明,该方法能够提高仿真精度。

Load model has crucial effects on power system simulation and control.Due to the deficiency in traditional aggregation method that static loads and induction motors are assumed to be connected to the same bus,an aggregation method of load considering distribution network is presented.In this method,according to nodal voltage equation of distribution network,connection nodes were removed,while load nodes were retained.Then,according to the principle that active and reactive power losses were equivalent before and after aggregation,equivalent distribution network impedance was calculated with the retained nodes voltages and admittances of the reduced distribution network.Moreover,voltage of the fictitious bus was obtained with the voltage and injecting current of the power supply point and the equivalent distribution network.Furthermore,static loads and induction motors were displaced to the fictitious bus.Finally,according to the electromagnetic model,induction motors displaced to the fictitious bus were aggregated into a single one,and static loads were aggregated to a composite one.Because the distribution network impedance is considered,the aggregation model well preserves the characteristic of composite load model of distribution network.The active and reactive fitting errors are small.A case is also taken to validate that the proposed method can improve the simulation precision.