Voltage Static Stability Analysis Of UHVDC Transmission End Power Grid

With the implementation of the goal of "three types,two networks,world-class" proposed by State Grid Corporation of China,the UHVDC transmission system with UHV as the backbone backbone has become the key development object of State Grid Corporation of China.Through the construction of UHVDC transmission system project,the network interconnection between cross regional power grids can be realized,and the coordinated development of regional power grids can be realized.The UHVDC transmission network is a complex power network.The stability of the AC / DC system voltage will affect the safe and reliable operation of the DC system.However,there are few studies on the static voltage stability of the UHVDC transmission grid.Therefore,it is very important to analyze the static voltage stability of UHVDC transmission system for guiding the construction of UHVDC projects.This paper takes the UHVDC power grid as the research object,and carries out the voltage static stability analysis of UHVDC power grid.The main contents of this paper include:(1)This paper analyzes the mathematical model of HVDC system,mainly introduces the models and principles of converter control,transformer tap control and reactive power control in UHVDC System,and analyzes the combination of different control modes of converter;(2)Based on the principle of continuous power flow calculation method,the model of continuous power flow calculation method is given.On this basis,the algorithm principle and mathematical model of improved continuous power flow method based on Newton interpolation are proposed.The static voltage stability limit value is predicted by Newton interpolation,and the system voltage static stability analysis mathematical model is established;Considering the control mode of DC system and the control measures of discrete variables,the complete calculation process of improved continuous power flow method is given,and the static stability of system voltage is analyzed and calculated based on a domestic UHVDC power grid.(3)The voltage static stability evaluation index and stability margin calculation index including UHVDC power grid are established.Based on the improved continuous power flow method,the voltage stability of the sending end power grid under various typical operation modes and power growth modes is studied,analyzed and calculated.The weak bus voltagenode of the system is evaluated,which provides benefits for system operation,planning and construction Guidance.