Research On Control Strategy Of Grid Connected Inverter For LVRT

Environmental pollution and energy exhaustion are serious challenges facing people.Seeking green energy to replace traditional fossil energy has become a global concern.Grid-connected inverters,as bridges for new energy access to the power network,their reliability is essential for the safe operation of the power network.The faults and abnormal operation of the power network will also have an important impact on the grid-connected inverters.Therefore,the research on grid-connected inverters for grid anomaly countermeasure has become a hot spot.This paper takes grid-connected inverters to deal with grid anomalies as the research topic,and makes analysis,simulation and experimental verification of the relevant theory,the main research contents are as follows:1.Set up the mathematical model of the grid-connected inverters,derive their forms in different coordinate systems,calculate the voltage vector of the switch state,set up the control system of the vector control strategy based on indirect voltage orientation,and analyze the advantages and disadvantages of the control strategy.2.Study the current model predictive control strategy.The current model predictive control strategy is constructed,and methods such as delay compensation and vector angle compensation are proposed to solve the problem of inaccurate dynamic response.The simulation verifies the feasibility of the control scheme,and provides theoretical support for the next research to improve the technology of low voltage traversal on the network side.3.The model predictive control strategy of grid-connected inverters under power network failure is studied.This paper introduces the fault types of voltage drop in power network and the theory of reactive power support for power generation system under drop fault,studies the positive and negative sequence separation method based on double-order generalized integrator(D-SOGI)under power network failure,puts forward the predictive control strategy based on positive and negative sequence power control model,and conducts simulation studies under different conditions of power network failure to verify the correctness of the control system.4.The design idea of the hardware and software of the control system is described,and an experimental platform of the inverter based on DSP28335 is set up,and the control strategy proposed is tested and verified.The experimental results show that the scheme adopted in this paper is feasible.