与超高压输电线路加装串补装置有关的系统问题及其解决方案
钟 胜
(中南电力设计院，湖北省 武汉市 430071)
PROBLEMS CAUSED BY ADDING SERIES COMPENSATION DEVICES TO EHV TRANSMISSION SYSTEM AND THEIR SOLUTION
ZHONG Sheng
(Mid-South China Electric Power Design Institute，Wuhan 430071，Hubei Province，China)
ABSTRACT：Taking the Fixed Series Compensation (FSC) and the Thyristor Controlled Series Compensation (TCSC) respectively installed at Hechi and Pingguo substations in South China Power Grid for example, the situation of power grid after the series compensation devices are installed is deeply researched and it is pointed out that a series of systematic problems, such as the arising of overvoltage level, enlargement of coupling current and the possibility of taking place the subsynchronous resonance (SSR), are caused by the inherent characteristics of series compensation devices. After the research it is held that when internal fault takes place in the transmission line where the series compensation device is located, the corresponding protective measures, e.g., the forced triggering the by-pass gap, etc., is the effective approach to avoid the appearance of excessing level of transient recovery voltage (TRV)and oversize coupling current. In addition, in order to suppress or avoid SSR it is suggested to install the devices such as the secondary equipments to suppress or monitor the subsynchronous resonance.
KEY WORDS：Series compensation；Overvoltage；Coupling current；Subsynchronous resonance (SSR)；Transient recover voltage (TRV)；Power system
摘要：文章结合我国南方电网河池固定串补及平果可控串补工程，对超高压输电线路装设串联电容补偿装置后的系统状况进行了比较深入的研究，指出一些系统问题，如过电压水平升高、潜供电流增大和可能发生的次同步谐振均源于串联电容补偿装置的固有特性，通过研究认为当串补所在输电线路发生内部故障时，采取强制触发旁路间隙等保护措施，是避免出现系统恢复电压水平超标和潜供电流增大等问题的有效途径。此外，还建议在串补站内装设抑制或监视次同步谐振的二次装置以抑制和避免系统发生次同步谐振。
关键词：串联电容补偿；过电压；潜供电流；次同步谐振(SSR)；暂态恢复电压(TRV)；电力系统
1 引言
采用串联电容补偿技术可提高超高压远距离输电线路的输电能力和系统稳定性，且对输电通道上的潮流分布具有一定的调节作用。采用可控串补还可抑制系统低频功率振荡及优化系统潮流分布；但在系统中增加的串联电容补偿设备改变了系统之间原有的电气距离，尤其是串补度较高时，可能引起一系列系统问题，因此在串补工程前期研究阶段应对这种可能性进行认真研究，并提出解决问题的相应方案及措施。
我国南方电网是以贵州、云南和天生桥电网为送端、通过天生桥至广东的三回500KV交流输电线路及一回500KV直流输电线路与受端广东电网相联的跨省(区)电网，2003年6月贵州—广东的双回500KV交流输电线路建成投运，南方电网形成了送端“五交一直”、受端“四交一直”的北、中、南三个西电东送大通道。随着南方电网西电东送规模的进一步扩大，为提高这些输电通道的输送能力和全网的安全稳定水平及抑制系统低频振荡，经研究决定分别在平果与河池变电所装设可控串补(TCSC)及固定串补装置(FSC)。