Stability Analysis of Yunnan Power Grid including ±800kV UHVDC Transmission based on Full Dynamic Simulation

Mid and long-term stability of complex power system is a most prominent problem which conventional transient simulation can not resolve. This paper analyzes the dynamic voltage stability of Yunnan power grid including plusmn 800 kV UHVDC transmission in 2010 by using full dynamic software. Full dynamic simulation is such a method in which the electro-mechanical transient, mid- and long-term dynamic simulations are organically unified. Gear method with variable step-size and order is applied to realize full dynamic simulation. Main models for dynamic voltage stability are presented. The influence of OLTC upon voltage stability at serious disturbance is investigated and the effectiveness of full dynamic simulation for dynamic voltage stability is verified. The results show that Yunnan main power grid is strong enough to keep stable at the assumed serious fault, but 500 kV OLTC automatic regulation post fault may result in voltage instability if system has not enough reactive power reserved.