影响多馈入直流系统换相失败的电网薄弱区域快速识别方法

A Rapid Identification Method of Weak Areas in Power Grid Based on Commutation Failure Analysis in Multi-infeed HVDC Systems

准确而快速地识别会导致多馈入直流系统发生同时换相失败的交流电网薄弱区域,对于保证电网安稳运行具有重要意义,针对目前研究方法主要采用仿真手段且应用场合无法覆盖整个交流系统的情况,文中提出一种影响多馈入直流系统换相失败的电网薄弱区域快速识别方法。将交流线路故障点视为广义节点,基于广义节点阻抗矩阵定义电压关联因子,根据最小关断角标准推导临界电压关联因子指标的解析表达式,此指标可以作为表征直流系统抵御换相失败的能力的特征参数。从理论上推导电压关联因子的3种交流线路故障位置分布特性,并给出确定换相失败关联域的方法,通过此方法能够在电网拓扑结构图上直观地展示引起逆变侧发生换相失败的薄弱区域。南方电网多馈入直流系统算例的分析结果表明所提指标的有效性以及薄弱区域快速识别方法的实用性。

To identify weak areas accurately and fast, within which ac system faults will adversely induce concurrent commutation failure among inverters, is of great significance to the safe and stable operation of power grid. Considering that the related study is mainly performed with simulation tools and its application can not cover the entire ac systems, a rapid identification method of weak areas in power grid based on commutation failure analysis in multi-infeed HVDC systems was put forward. With the ac line fault location regarded as a generalized node, the voltage correlation factor（VCF） was defined based on a generalized node impedance matrix. Based on the minimum extinction angle criteria, the analytical expression of critical voltage correlation factor（CVCF） was derived, through which the immunity of inverters to commutation failure in HVDC systems could be effectively characterized.Meanwhile,the correlation between VCF and the variability of ac line fault locations was expressed and the method to determine commutation failure correlation region（CFCR） was proposed, through which the weak areas can be shown visually in the grid topology map.The validity of proposed index and the applicability of aforementioned method are verified by the calculation results based on the multi-infeed HVDC system model of China Southern Grid.