Research On Anti-island Performance Testing Device Model Of Photovoltaic Power Supply Based On Controllable Device Load

As society continues to grow,the demand for electrical energy continues to increase.On the other side,the environmental pollution caused by the consumption of traditional fossil energy that promotes the rapid development of clean energy represented by solar energy and wind energy.At the same time,Distributed power generation technology is also developing along with the wave of clean energy development,and increasingly becoming an important part of the power grid.Then,if the distributed generation system fails to detect and disconnect from the grid in time due to loss of power on the grid side,it may pose a threat to the personal safety of power generation equipment and related maintenance personnel.Therefore,the equipment needs to be tested for its anti-island performance before connecting to the grid.The traditional distributed power anti-island performance test device usually uses RLC as the load.This kind of equipment consumes a lot of energy during the test and its huge size is not suitable for the needs of the current society.With the development of power electronics technology,a distributed power supply anti-island test device based on power electronic load has emerged.Aiming at the distributed power supply anti-islanding test device for power electronic load,this paper proposes an improved deadbeat control strategy,which reduces the response speed of the device and improves the power quality of the grid-connected output.It has good engineering application value.In this paper,from the common PWM converter,the three-phase six-bridge VSR is selected as the inverter of the anti-island performance test device.Then from the working principle,the reason why the PWM converter can be used as the pre-load analog converter and the post-stage grid-connected inverter is deduced.It is pointed out that it can work in pure resistive load,pure inductive load and resistive load and RC.The operational characteristics of the sexual load.A no-beat control strategy with fast response time is selected in the control of the pre-load analog converter.Then the principle and implementation method of the deadbeat control are deduced,and it is pointed out that the conventional deadbeat control is equivalent to the control of lagging one beat in the control timing,which will have a bad influence on the dynamic response speed and steady state accuracy of the system.Aiming at this problem,a feedback correction based on the internal model principle is proposed to correct the steady-state error.The control principle is to correct the predicted power of each step.The specific step is to superimpose the prediction error of each control period,and correct the prediction error of the next control period in time,and then feedback correction to finally eliminate the steady-state error.The grid voltage vector control technology is selected for the grid-connected inverter of the latter stage,that is,the double closed loop control strategy.Then the voltage vector control technology and the three-phase phase-locked loop technology under various working conditions are derived.Finally,in the SIMULINK module of MATLAB,the simulation model of the anti-island performance test device is built according to the above principle.Simulation is performed for purely resistive load,resistive load,resistive load and anti-island test performance.The simulation results show that the control strategy is correct and effective.