基于主网和馈线多负荷等值的配电网合环倒切可行性分析

Feasibility analysis of loop closing operation in a distribution network based on the main network and feeder load equivalent model

配电网合环倒切可能会产生较大的合环稳态电流和冲击电流。建立合环电路等值模型计算合环电流,分析其倒切可行性,是保障电网安全稳定运行的基础工作。针对现有合环模型、电流计算方法误差较大的问题,首先提出考虑主网等值、馈线多负荷等值和变压器等值的合环电路等值模型。其次,结合叠加定理、前推回代法和牛顿拉夫逊法计算合环稳态电流,解决了迭代可能不收敛的问题。然后,基于戴维南等值电路对合环暂态过程进行分析,利用最佳频率法推导了精确合环冲击电流的表达式。最后基于PSCAD软件搭建仿真模型,得出该合环电流计算方法误差最小,验证了所提出等值模型与计算方法的准确性与优越性,对于安全进行合环倒切操作具有重要意义。

The loop closing operation of a distribution network may generate a larger steady-state current and impulse current.To establish the equivalent model of the loop closing operation to calculate the current and analyze the feasibility is the basis of ensuring the safe and stable operation of a power grid.For the problem of large errors in existing loop closing models and current calculation methods,this paper proposes a loop closing circuit equivalent model that considers main network,feeder multi-load and transformer equivalences.Second,it combines a superposition theorem,a forward and backward substitution method and the Newton Raphson method to calculate the loop closing steady-state current.This can solve the problem that iteration may not converge.Then,it analyzes the loop closing transient process based on the Thevenin equivalent circuit and derives the expression for the loop closing impulse current by using the optimum frequency method.Finally,the simulation model is built based on PSCAD software,and it is concluded that the error of the calculation result of the proposed method is the smallest.The accuracy and superiority of the proposed equivalent model and calculation method are verified.This is of significance for the safe loop closing operation.