Virtual Synchronous Machine Modeling And Control Strategy Simulation

With energy and environmental problems receiving much attention around the world,the development of renewable energy becomes a trend.Under this background,Wind power has been constantly developed and utilized.The increasing wind turbine,which is used to replace partial synchronous generator,not only lowers the ability of the system to adjust frequency and voltage,but also reduces the total inertia and damping.It will affect the system's overall ability to resist disturbance and the stability.In order to solve above problems,this essay starts from virtual synchronous generator mathematical model,and then presents a method of adding virtual synchronous generator in the grid-inverter control of wind power unit.As for large grid voltage variation,frequency variation,short-circuit fault at the outlet of the wind turbine generator,short-circuit fault at the end of the wind turbine connected to the infinity system,changes of the capacity of the wind turbine,changes of the wind speed of the wind turbine,and changes of the length of the line,the simulation models of the classical operating conditions that may degrade the system's ability to operate stably are established.The time-domain simulation curves were compared,and the influence of the wind turbine's control on the stability of the system by adding virtual synchronous generators was analyzed.The following conclusions are drawn: with the VSG control strategy added to the DFIG gridwork-side converter,the stability of the system can be improved.However,the output power of the DFIG will oscillate when transmission line is long,the wind speed is fast and the DFIG's installed capacity is large.In order to further improve the stability of the system,this paper proposes a strategy to control the virtual synchronous generator using the port-controlled Hamiltonian model which refers that the synchronous generators use the PCH method to design the dynamic system stabilizer.A PCH-based VSG simulation model was established to verify the validity of the strategy through simulation analysis.