Research On Inverter Control Strategy With Voltage Regulation Characteristic

With the energy crisis and the continuous increase of environmental pollution,distributed generation technology using new energy to generate power has been rapidly developed rapidly,and the penetration of distributed generation in traditional power systems has been continuously increased.As the interface between new energy generation and power grid,inverter’s safe and stable operation plays a crucial role in the power interaction between new energy and power grid.The performance of the inverter will directly affect the power quality of the whole distributed generation system.Therefore,it is very important to study the inverter control strategy with reasonable control structure and flexible operation mode.In order to improve the flexibility and economy of inverter operation,an inverter control strategy with voltage regulation is proposed in this paper.The control strategy equates the inverter to a controlled voltage source connected in series with a controllable output impedance.The amplitude of the controlled voltage source can be adjusted linearly through the pressure regulating shaft of the axial pressure regulator in the control loop.The controlled voltage and output phase of source can be adjusted linearly by the frequency modulation axis of the axial pressure regulator in the control loop and there is no coupling between the pressure regulating shaft and the frequency modulation shaft in the axial pressure regulator,so that independent control can be achieved and the inverter running flexibility.At the same time,the equivalent output impedance of the inverter is only related to the parameters of the inverter control loop and the filter inductance on the grid side,and the relevant characteristics and numerical values of the equivalent output impedance of the inverter can be controlled through reasonable parameter design.The decoupling control between the active power and the reactive power of converter,may be provided.In this paper,mathematical analysis and formula derivation of inverter control strategy are given,and the Thevenin equivalent circuit of inverter is established.On this basis,the power transmission characteristics of the inverter are mathematically analyzed and verified by simulation.The reasons for the DC current in the inverter output current are analyzed in detail and the formulas are deduced.A DC offset compensation Control strategy to eliminate the adverse effects caused by the injection of DC component into the power grid.At the same time,the DC offset compensation control strategy is extended to the DC component elimination of current control inverter.Based on the above analysis,Inverter control strategy proposed a PQ control strategy,and completed the power ring small signal modeling and controller parameter tuning;the power control strategy combined with droop control features,so that the inverter has a voltage regulator Characteristics,can provide effective support for the safe and stable operation of the power grid.In this paper,theoretical analysis is also given the relevant software simulation and hardware experiments to verify the correctness of the theoretical analysis and the effectiveness of the proposed control strategy.