直流输电准稳态模型有效性的仿真验证

SIMULATION VALIDITY TEST OF THE HVDC QUASI-STEADY-STATE MODEL

换流器的准稳态模型在高压直流输电(HVDC)工程的规划和设计中得到了广泛的应用,该模型以换流站交流母线电压作为换相电压,以换流变压器的漏抗作为换相电抗,忽略交流系统侧的影响。该文从经典换流理论出发,分析了准稳态模型与经典换流器模型(经典模型)之间的矛盾,并针对不同强度的交流系统,利用仿真的方法,对准稳态模型的有效性进行了验证。仿真结果表明:如果换流站交流母线装设有完善的滤波装置,则多桥换流器中各个换流桥之间可以认为是解耦的,因此,利用准稳态模型计算能够达到工程要求。

The Quasi-Steady-State (QSS) model of the HVDC converter has been widely used in the planning and design of HVDC projects. In a QSS model, the commutating voltage is the voltage at the converter bus, the commutation reactance is the leakage reactance of the converter transformer, and the impact of the AC system impedance is ignored. This paper analyzes the conflictions between the QSS model and the classical converter model based on the classical commutation theory. Digital simulations corresponding to various AC systems with different Short Circuit Ratios (SCR) have been done to evaluate the QSS model. The results show that, if the commutating voltage is well filtered, the converters connected in series in a multiple-bridge converter can be independent, namely, decoupled, and the calculations with the QSS model are appropriate in engineering application.