解列后局部孤网的自适应第三道防线配置方法

Third Defense Line Configuration Method Adaptable to Isolated Local Power Grid After Splitting

通过薄弱交流断面与主网相连的局部电网在断面解列后转为孤网运行时,容易出现频率稳定或电压稳定破坏问题。以某实际局部电网发生的一起全停事故分析了现有低频低压切负荷和过频切机配置方法的不足,提出一种适用于解列后局部孤网的低频低压切负荷和过频切机配置方案,以改善第三道防线对孤立电网运行方式或电网规模变化的适应性。其主要思路是将低频低压切负荷及过频切机方案分为速动区和补偿区,前者用于快速平抑不平衡功率冲击,避免频率或电压大幅偏移;后者用于避免频率或电压快速变化时,低频低压切负荷或过频切机多轮次相继动作导致过控。基于实际电网的仿真结果验证了所述方法的有效性。

The frequency and voltage stability of local network connected to the main power grid would probably be damaged when the weak transmission interface tripped. The inadequacy of traditional underfrequeney load shedding （UFLS）, undervoltage load shedding （UVLS） and over-frequency generator tripping （OFGT） configuration in an actual local power grid is analyzed. A new UFLS/UVLS and OFGT configuration scheme suitable for the local isolated power grid is proposed. Its key technique is to divide the UFLS/UVLS or OFGT into the celerity region and the compensation region. The former is used to quickly reduce the power imbalance and avoid a significant frequency or voltage offset while the latter to avoid the muhi circle successive action of UFLS/UVLS or OFGT when the frequency or voltage is rapidly varied to lead to over-controlled situation. The time domain simulation results of an actual power grid verify effectiveness of the proposed method.