暂态低频高压驱动的直流馈入电网减负荷紧急轮配置方案

针对相控换流式直流(LCC-HVDC)闭锁扰动下受端电网的低频控制问题,考虑事件发生后固定暂态响应模式,提出一种基于事件特征驱动的减负荷紧急轮配置方案。首先推导了LCCHVDC闭锁故障时刻受端电网频率和电压的变化规律,然后分析了延迟联切换流站无功补偿装置造成的低频高压现象。接着采用灰色关联分析方法提取电压信息,并结合初始频率变化率,利用k-近邻算法匹配动作方案。在传统低频减载的基础上,附加紧急轮以应对LCC-HVDC闭锁故障,由就地监测的低频高压特征驱动,实时匹配决策表以切除故障区域负荷。最后以某省级电网为例,对所提出方法的有效性进行了验证。

Configuration Scheme of Emergency Load Shedding for HVDC Receiving-end Power Grid Based on Transient Low-frequency and High-voltage Features

In view of the under-frequency control problems of receiving-end power grid subjected to blocking faults of line-commutated converter-based high-voltage direct current(LCC-HVDC), a feature-driven scheme of emergency load shedding is proposed by taking into account the regular response pattern after the faults occur. The changing rule of frequency and voltage at the instant of LCC-HVDC blocking fault is derived, and the low-frequency and high-voltage feature caused by time-delay inter-tripping of reactive power compensation devices is analyzed. Moreover, the partial voltage characteristics are extracted by grey correlation analysis, and the initial changing rate of frequency is used to match the action scheme by k-nearest neighbor algorithm. On the basis of the traditional under-frequency load shedding scheme, an emergency load shedding stage is added to deal with the LCC-HVDC blocking fault, and the local-monitored low-frequency and high-voltage feature is used as the operation criterion, and is adopted to match the decision table in real time to cut off the load of fault areas. Finally, a provincial power grid is taken as a case to validate the effectiveness of the proposed scheme.