中压配电网合环电流计算方法研究

Study of calculation of current induced by closing-loop operation in medium-voltage distribution grid

为解决电网调度人员生产实际中遇到的合解环问题,通过对合环后等值电路进行精确理论分析,建立了考虑主网等值并计及变压器非标准变比影响的10 kV配电网合环等值网络,可适用于一般典型合环情况的计算分析。基于此等值网络,提出三种综合考虑计算复杂度和结果精确度的合环电流实用计算方法,包括计及主网等值阻抗的潮流法、忽略主网等值阻抗影响的潮流法及近似公式法。基于供电公司实际生产需求,对上海电网实际生产中的典型合环操作问题在不同负荷的不均衡程度、主变档位情况下采用此三种方法进行合环电流计算,并与基于BPA的全网精确仿真结果进行误差比较。仿真结果表明,所提出的三种简化计算方法均可满足生产实际要求,可为实际生产决策提供切实可行的合环电流计算依据。

To solve the closing loop current calculation problem for dispatcher in actual production in medium-voltage distribution grid,an accurate theoretical analysis for the equivalent circuit after closing loop is conducted,and a typical equivalent circuit considering equivalent circuit of transformers with off-normal tap ratio is built up for the calculation and analysis of the typical 10 kV closing-loop system.Three methods considering both the calculation complexity and the result accuracy,namely detailed power flow analysis method considering the main grid equivalent impedance,simplified power flow analysis method neglecting the equivalent impedance and approximate formula method are proposed based on the typical equivalent closing-loop system.In the case study,the closing-loop current of 10 kV distribution grid of Shanghai under various operation scenarios is calculated with the three methods respectively,and the influence of the load levels and transformers’tap positions on the closing-loop current is analyzed in accordance with the practical requirements of dispatching.The effectiveness of the three methods is proved through comparison of the calculation results with full-network simulation results through BPA software.Simulation result shows that the three methods proposed can meet practical requirements,thus to provide a feasible and reliable decision basis for practical distribution grids dispatching.