Research On Dynamic Performance Of New Generation Synchronous Condenser In HVDC Transmission System

The high-voltage DC transmission system cannot transmit reactive power,so its large amount of feeding weakens the receiving power grid's ability to withstand reactive power shocks,which makes the problem of voltage stability become more serious.As a result,commutation failures in DC inverter stations can easily happen,which may induce the collapse of the entire system,so it is particularly important to configure a large-capacity dynamic reactive power compensation device in the inverter station.Aiming at the problem of reactive power and voltage of the weak receiving end of HVDC transmission system,according to the stable operation requirements of the AC and DC system,this paper analyzes the impact on the AC and DC system when the new generation synchronous condenser connecting to the inverter station,and makes research and improvement on excitation control about the shortcomings in power compensation of synchronous condenser.First,the equations of the synchronous motor are used to analyze the key parameters that affect the output characteristics of synchronous condenser at each stage,and a series of laws of the reactive output and the parameters of synchronous condenser are obtained,and the correctness of the theoretical analysis is verified according to the simulation results,which lays the foundation for the configuration of synchronous condenser parameters during the subsequent simulation model building.Then in view of the voltage instability caused by various faults of the AC and DC systems on both sides of inverter station,this paper simulates the changes of various electrical quantities before and after the installation of synchronous condenser in the inverter station to analyze the lifting capacity of supporting voltage,suppressing the inverter commutation failure,and maintaining the DC system active.In the HVDC transmission system studied in this paper,the amplitude of the voltage allowed to drop can be doubled to ensure that there is no commutation failure after installing a synchronous condenser,and the synchronous condenser can also absorb reactive power from the system when the voltage rises to reduce overvoltage.These conclusions can prove that the new generation synchronous condenser can meet the dynamic reactive power demands of the inverter station during the faults and maintain the smooth operation of the HVDC system.Finally,the excitation system of the new generation synchronous condenser is further improved in reactive power compensation.Combining PID control and fuzzy control theory,the fuzzy PID control system is used to control the nonlinear system of synchronous condenser in real time.The control effect of the designed fuzzy PID excitation system is verified by different AC and DC faults.