送端感应电动机负荷无功特性对送出极限的影响

Influence of Reactive Power Characteristic of Sending-end Induction Motor on System Sending Limitation

通过分析计及转子电磁暂态的三阶感应电动机负荷模型在定子三相接地过程中的响应,指出位于系统送端的感应电动机负荷的无功倒送特性在一定时段内对系统送端电压有一定的支撑作用。分析了电压支撑作用对系统送出极限的影响。将华北电网典型送端张家口地区实测综合负荷模型(以感应电动机为主)应用于沙岭-昌平线极限切除时间的计算,并与采用不同比例ZIP负荷模型的计算结果进行比较,验证了理论分析的结果。说明张家口地区(送端)负荷模型对系统送出极限的灵敏度很高;动态负荷模型具有静态负荷模型难以模拟的特性。强调了在电网稳定计算中采用动态负荷的必要性,从无功角度研究了负荷模型在暂态稳定计算中的应用,提供了新的思路。

The dynamical response of three-order induction motor based load model is analyzed when its stator windings is grounded. As a result, this paper proposes that during disturbance the reactive power releasing of induction motor located in sending-end would sustain system voltage. It benefits system stability. Measured integration load model (induction motor + ZIP) and static load model (ZIP) of Zhangjiakou district are used to calculate critical clearing time of Shaling-Changping 500 kV line. And the Comparison of results verifies the theoretical analysis. This paper emphasizes the validity of measured dynamic load model and presents a new idea, which is to study power system transient stability from the point of reactive power view.