TCSC阻抗特性及其导通角对次同步谐振的抑制分析

Impedance characteristics of TCSC and its conduction angle for sub-synchronous resonance mitigation

为了解决目前普遍应用的TCSC基波阻抗公式无法解释次频正电阻的问题,推导了TCSC基波阻抗的复数表达式,提出了TCSC导通角的选择依据。利用基波阻抗的复数形式,分析得到TCSC受导通角影响,基波电抗呈现出感性或容性特征,基波电阻会表现出负电阻和正电阻特性;次频电抗也会表现出感性或容性特征,次频电阻始终呈现正值。通过改变导通角使次频电抗呈感性能有效抑制SSR,使工频电阻为负值能够给次频正电阻提供能量;导通角的选择应同时满足工频下电抗呈容性、次频下呈感性以及工频下电阻为负值。算例分析表明,TCSC基于上述依据选择导通角能有效抑制系统的SSR,证明了导通角选择的合理性和基波阻抗表达式的正确性。

In order to explain the positive resistance phenomenon of sub-synchronous frequency based on the commonly used fundamental frequency impedance of TCSC, the complex expression of fimdamental frequency impedance is derived and selection principle of TCSC conduction angle is proposed. The fundamental frequency reactance of TCSC is capacitive or inductive and its resistance will be negative or positive. The sub-synchronous reactance of TCSC will also be capacitive or inductive and the sub-synchronous resistance is always positive with conduction angle＇s influence. Inductive reactance plays a major role for SSR mitigation and power frequency negative resistance provides energy to the positive resistance under sub-synchronous frequency. TCSC conduction angle＇s selection should make sure that the reactance should be capacitive under power frequency, and inductive under sub-synchronous frequency, meanwhile the power frequency resistance should be negative. Simulation results show that TCSC can mitigate SSR effectively based on the above basis. It proves rationality of selecting the conduction angle and correctness of the fundamental frequency impedance exnression