高比例变流型电源并网的输电系统三相短路电流计算

Three-phase Short-circuit Current Calculation for Power Transmission System with High Penetration of Converter-type Sources

高比例变流型电源接入输电系统可能提高系统短路电流水平,导致电力设备选型面临更高的动热稳定要求。通过分析变流型电源实验平台的短路电流测试波形的包络线变化规律,获取其三相短路电流表达式。根据变流型电源在故障不同阶段呈现的短路电流输出特性,提出故障暂态和稳态阶段的等值电路。应用叠加定理分别计算含变流型电源电网短路电流交流分量和直流分量,并对冲击电流进行评估,其结果可用于电网规划及设备选型;最后用6节点的500 kV淮南电网和35节点的220 kV淮宿电网实际算例,将所述方法、常规电压源等值法的计算结果与电磁暂态仿真结果进行对比,验证了所述方法的有效性。

Short-circuit current level of power transmission system may increase with high penetration of converter-type sources, and power equipment selection will be faced with higher requirements for dynamic and thermal stability. Three-phase short-circuit current expression of converter-type sources is obtained by analyzing measured short-circuit current waveform and its change rule of envelope line. According to current output characteristics presented by converter-type sources in different periods of fault, equivalent circuits of fault transient state and steady state are proposed. In power grid with converter-type sources, superposition theorem is used to calculate AC component and DC component of short-circuit current. Then the peak value of short-circuit current is evaluated effectively, and the calculation results can be used for grid planning as well as equipment selection.Finally, the calculation results of proposed method and conventional method are compared with that of electromagnetic transient through 6-node 500 kV Huainan power grid and 35-node 220 kV Huaisu power grid, then effectiveness of the proposed method is verified.