发电机过励磁限制器的作用可能导致电力系统电压中长期失稳，而低压切负荷控制是一种防止电压失稳的有效方法。以分布式闭环低压切负荷控制为基础，增加了用于应对严重故障的备用切负荷控制，从而形成了基于WAMS的低压切负荷控制策略。该策略以发电机过励磁限制器是否启动作为电压失稳的预测判据，并在电压下降的过程中通过多轮次闭环切负荷控制防止系统电压崩溃。该策略的控制方式能够基于系统动态变化过程进行实时调整，能够应对严重故障下由过励磁限制器作用引起的中长期电压失稳。仿真分析在改进的IEEE 39节点系统中展开，结果表明了该策略的有效性。%The effect of machines’ over excitation limiters may cause long-term voltage instabilities in power systems, and undervoltage load shedding is an efficient method to prevent voltage instabilities. On the basis of undervoltage load shedding using distributed controllers, this paper presents a new strategy for undervoltage load shedding based on WAMS. This strategy takes the degree of load voltage drop and the activating signal of machines’ over excitation limiters as the criterion to activate the load shedding control, and prevents the power systems from voltage collapse by repeated closed-loop load shedding. This strategy adjusts instantly according to the system’s dynamic evolution, which is of inverse-time characteristic, and it is able to protect systems from long-term voltage instabilities caused by the effect of over excitation limiters in serious fault. The simulation studies have been carried out on the modified IEEE 39 system, and results show that the proposed strategy is efficient.
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