摘要
为分析线路差动保护对交直流混联电网的适应性,利用RTDS试验数据仿真了在直流系统换相失败、交流线路区外故障以及区内高阻接地故障时线路差动保护的动作特性,结果显示线路差动保护在上述情况下存在可靠性不高或灵敏度下降的问题。差动电流频谱分析表明,流过线路并联电抗器的非周期分量和低频分量是造成保护动作性能降低的原因。为此,采用参数识别的思想提出了一种基于并联电抗器的纵联保护原理,将内部和外部故障的模型统一简化为电感模型,通过比较模型中电感参数的符号和幅值来区分内部和外部故障。RTDS试验数据表明,该方法能可靠区分内部和外部故障,有效克服了电流中非周期分量和低频分量的影响,证明了新原理的正确性和有效性。
The operating characteristic of current differential protection applied to AC-DC hybrid grid has been analyzed with the RTDS data of Northwest AC-DC power system in China, and results show that the performance of current protection is poor in the following situations such as external faults in AC system, the commutation failure in DC system and internal faults with high transition resistance. According to the spectrum analysis of the differential current, it is clear that the non-periodic and low-frequency components of the fault current flowing through the shunt reactor on the protected line are responsible for the degradation. Therefore, a novel type of pilot protection based on parameter identification is proposed to prevent from the impact of the non-periodic and low-frequency components. R-L models in the same form are established for the internal fault state and the external fault state. According to the sign and value of L, the internal fault and external fault can be distinguished correctly. Simulations show that this method is valid and is capable of detecting the faults occurring on the protected line quickly and accurately. Furthermore, it is not sensitive to transition resistances and transient components.
出处
《电力系统保护与控制》
EI
CSCD
北大核心
2012年第24期34-39,共6页
Power System Protection and Control
基金
国家自然科学基金资助项目(50677051
50677061)~~
关键词
交直流混联电网
差动保护
并联电抗器
纵联保护
参数识别
AC-DC hybrid grid
current differential protection
shunt reactor
pilot protection
parameter identification
