Research High Power Grid Simulator Based On PI And QPR Double Closed-loop Control

With the rapid development of distributed energy resources,more and more wind power systems are connected to the grid,and the scale of wind turbine generator systems has been expanding respectively.According to standards,the ability of wind turbine generator systems to cope with different grid faults must be tested before they can be integrated into the grid to ensure that the actual grid is not malfunctioned.Due to the randomness and uncontrollability of the grid,a grid simulator is used to simulate and generate different grid faults to test the performance of wind turbine generator systems.The main research contents of this paper include: analyzing the working principle and functional requirements of the grid simulator,designing the rectifier side;improving the control strategy of the inverter side;analyzing and compensating the delay in the inverter.1.In the first place,the background of wind power generation and grid simulator technology is investigated.Then,the main functional requirements of the grid simulator are formulated based on the current faults in the grid,such as imbalance of simulating three-phrase voltage and mutations of the voltage amplitude.Besides,the rectifier side of the grid simulator is introduced and the design plan is proposed.2.The inverter side of the grid simulator is used in this paper.In response to the demand for the command voltage with harmonics in the output of the grid simulator,it is proposed to select an inverter-side filter that meets the requirements according to the power grid simulator,and then calculate the filter parameters according to the requirements,and comprehensively consider the selection of the LC filter structure.3.Analyze three different modes of inner loop control from the negative feedback mode of the control system,and compare their advantages and disadvantages of control performance under different control conditions.Considering comprehensively,in order to improve the response speed and stability of the control,this article uses the terminal current of the device under test as the control method of the feedforward inner loop of the inductor current.A variety of feedback control methods are discussed and compared.Simulation and comparison prove the effectiveness of PI-QPR dual closed-loop control dynamic response performance and stability.4.Aiming at the problem of delay in the actual control system,delay compensation is used to increase the control rate and improve the control algorithm to reduce the delay error.In the modeling,the delay link is considered,and a high-performance FPGA is used as the controller.The quasi-proportional resonance control strategy is combined with the proportional integral control.5.A simulation model of the power grid simulator is established in MATLAB to verify the functional requirements of the power grid simulator proposed in this paper.Completed the construction of the experimental prototype of the rectifier side of the power grid simulator.Based on CHIL simulation technology,a hardware-in-the-loop physical platform was built to verify the effectiveness of the power grid simulator control strategy and the functional requirements of the power grid simulator.