交直流电力系统短路计算方法讨论

Discussion on Short-Circuit Computing Methods for AC/DC Power System

PSASP和BPA是国内使用十分普遍的两种短路计算程序,即使采用相同的计算模式和计算条件,两种程序的计算结果也可能存在差异。通过理论分析和仿真计算对产生差异的原因进行解析,着重讨论交直流系统短路电流有效值、短路容量、短路比及有效短路比的恰当计算方法。建议基于潮流计算短路电流时,把直流功率对应的等值阻抗计入短路计算所用节点阻抗矩阵中;计算短路比和有效短路比指标时,采用基于网络模式下、换流母线电压为1.0 p.u.时戴维南等值法的短路容量计算结果。以不同规模的交直流系统为算例,对所提提议的有效性进行分析,有助于完善电力系统短路计算理论的应用。

PSASP and BPA are the commonly used short-circuit calculation programs in China.Even under the same calculation modes and calculation conditions,their computed results could be different.This article analyzed the reasons for this difference by using theoretical analysis and simulation calculations.It focused on the effective value,short-circuit capacity,short-circuits ratio,and effectively short-circuit ratio of the proper computing methods for the short-circuit current in the AC/DC power system.This paper gives two suggestions:when calculating the short-circuit current based on the power flow,the equivalent impedance corresponding to the DC power could be included in the node impedance matrix used in the short-circuit calculation.When calculating the short-circuit ratio and effectively short-circuit ratio in-dicators.It might be better to use the short-circuit capacity calculation result which was figured out by using the Thevenin equivalent method based on the network-based mode when the converter bus voltage is 1.0 p.u..The result of this study could help to improve the application of short-circuit calculation theory in power systems.