题目

While the most common form of voltage instability is the progressive drop of bus voltages,the risk of overvoltage insta- bility also exists and has been experienced at least on one system [19].It is caused by a capacitive behavior of the network (EHV transmission lines operating below surge impedance loading) as well as by underexcitation limiters preventing generators and/or synchronous compensators from absorbing the excess reactive power.In this case,the instability is associated with the in- ability of the combined generation and transmission system to operate below some load level.In their attempt to restore this load power,transformer tap changers cause long-term voltage instability.

提问时间：2021-01-12

答案

而最常见的电压不稳定是一个逐渐下降的端电压,建成的风险也同样存在——过电压能力,而且已经经历过至少一个系统上(19).这是因为在电容行为的网络(超高压输电线路阻抗的负载运行下面激增以及underexcitation限制器等防止发电机和/或同步补偿器吸收多余的无功功率.在这个案例中,该失稳是联系在一起的——能力的结合在发、输电系统负荷水平下一些操作.在他们试图恢复该负载功率转换器,引起长期,变压器抽头电压不稳定.