35kV以下农网短路电流计算中应注意的问题

Points for Attention in Calculation of Rural Power Grid Short-circuit Current of 35kV and Below

35 kV及以下电压等级的农网与其它高压电网有不同之处,在进行短路电流计算时,若和35 kV以上的其它高压电网一样,采用通常的代数法和运算曲线法进行短路电流计算,会产生较大的计算误差,给电气工程设计、调试、运行带来严重影响。准确地进行35 kV以下农网短路电流计算,不但是进行电气设备选择和继电保护整定的基础,也是合理设计电气主接线和进行事故分析的重要依据;针对35 kV及以下电压等级的农网进行短路电流计算时容易忽视的问题作深入的分析,并提出解决计算误差的方法和通用判别式。

Rural power grid with the voltage of 35 kV and below is different with other high-voltage power grid. Using common algebraic and operating curving method to calculate short-circuit current will produce serious calculation error, bring great influence to the design, adjustment and operating of electrical engi- neering. An accurate calculation of short-circuit current is not only the base to select electric equipment and adjust relaying, but also the important gist to design primary connection wires and analyze electric accidents. Problems easily ignored in short circuit calculation in rural power grids below 35 kV were analyzed and methods and general discriminant to solve calculation errors were suggested.