INVESTIGATING THE INFLUENCE OF CONTROL SYSTEMS OF MULTI-INFEED HVDC SYSTEM ON AC/DC POWER SYSTEM VOLTAGE STABILITY BY MODAL ANALYSIS METHOD

This paper presents a rigorous method to investi- gate the influence of control systems of multi-infeed HVDC system on AC/DC power system voltage stability. For this purpose, a continuous power flow computation method, which takes into account power system controls not only the Automatic Voltage Regulator (AVR) and the speed governor (GOV) in power genera- tion but also voltage control systems such as the On-Load Tap Control (OLTC) and the Automatic Control of Shunt Capacitor (ACSC), etc., is proposed in this study. Furthermore, modal analy- sis method was applied to the voltage stability analysis of multi- infeed HVDC systems to study the mechanism of voltage stability. The computation results from an AC/DC model system with dual HVDC systems verified the efficiency of the proposed method and quantitatively illustrated the influence of control systems of HVDC system and Over Excitation Limiter (OEL) on AC/DC power system voltage stability.