Virtual Synchronous Genarator Power Decoupling Control Technology Research

With the increasing proportion of new energy sources such as wind and solar energy in the power system,the energy composition in the traditional power system has changed.The electrical energy integrated into the grid in a traditional power system is through a synchronous generator,and most of the new energy integrated into the grid is through the inverter.When more and more microgrids are integrated into the grid,it will have a great impact on the inertia torque in the traditional power system.The virtual synchronous generator can change the inverter's control algorithm so that the inverter can reflect the characteristics of the synchronous generator,thus solving the impact on most of the new energy integrated into the grid.However,in the power regulation process,the virtual synchronous generator(VSG)has coupling between the active power and the reactive power,which causes coupling overshoot fluctuations in the dynamic regulation process and steady-state error when the power reaches the steady state which lead to the failure of the control system.Aiming at this problem,this dissertation studies the coupling characteristics of the VSG,and proposes the method of decoupling by series compensation after static decoupling by rotating coordinate method.It is convenient to calculate the dynamic coupling compensation amount and realize the dynamic coupling overshoot suppression.The details are as follows:(1)Firstly,the VSG circuit structure diagram is introduced.The VSG is introduced from the active power loop and the reactive power loop,and the two mainstream VSG modeling methods are compared and analyzed.(2)After the static decoupling is obtained,the dynamic coupling structure of VSG is obtained by small signal analysis method,and the dynamic coupling degree of the two VSG models is analyzed by relative gain method.For the dynamic coupling suppression between VSG active power and reactive power,the series compensation is adopted to achieve the decoupling of the active power and reactive power.(3)In order to verify the stability of the system after the series compensation is added to the VSG,the stability comparison analysis is performed on the system after the series compensation is not added and the series compensation is added.The analysis indicates that the series compensation will not affect the stability of the system.Finally,the correctness of the theoretical analysis and the effectiveness of the decoupling method are verified by simulation and experiment.