Study Of The Voltage Stability Of Inverter AC Bus In HVDC System And The Influence Of Load Characteristic

With the developing of national economy, the power demands of all trades become bigger and bigger, and it is not only an opportunity but also a challenge for the development of electrical power system. To meet the demands and minimize the operation cost of power system, as a novel technology, HVDC system will play an increasingly important role. At the same time, the voltage stability is very important for the regional stability, and the overall development of economy produces the variety of loads, thereby studying the voltage stability of inverter AC bus in the HVDC system and influence of load characteristic becomes more important.This paper introduces the advantages of HVDC transmission and some parameters used in evaluating the stability of HVDC system. It focuses on the relationship between stability and the SCR, ESCR, VSF. Based on this, the expression of CSCR is derived, and the relation between MAP and VSF under particular control condition is demonstrated theoretically. Furthermore, considering the load characteristics, the expression of CSCR in single-feed system is deduced, which provides the foundation for studying the stability problem analytically.The electromagnetic-transient simulation software —PSCAD/EMTDC is used to carry out the simulation tests on the HVDC benchmark of CIGRE for different inverter load characteristics . The simulation results are compared with the theoretical values. The final analysis indicates that the load characteristics and some other parameters influence the voltage stability of inverter AC bus significantly.