Research Of QPR Control Strategy Of LCL Type Grid-connected Inverter

With the exhaustion of energy resources today,the development and utilization of new energy resources is imminent.The grid-connected inverter,as a device to connect new energy and power grid,is an important part of photovoltaic power generation system.In this paper,based on the traditional control strategy,the LCL grid-connected inverter under the alignment PR control is studied.In this paper,the main content is as follows:First,in this paper,the grid inverter sine pulse width modulation method are introduced,and the inverter side of LCL filter inductance,mesh side inductance and filter capacitor are analyzed respectively,and the design method and the harm of LCL filter resonance peak problems and solutions including passive damping method and active damping respectively by calculation are analyzed in detail.Secondly,through the calculation and analysis of the mathematical model of the LCL grid-connected inverter,this paper obtains its simplified model and transfer function.For the inner loop control,the active damping control of capacitive current feedback is used to target the LCL filter at resonance.Solve the problem of resonance spikes at the frequency;for the outer loop control,the grid-side current quasi-PR control is adopted to achieve the static error-free tracking of the AC signal.After that,through calculation and derivation,the structural block diagram and transfer function of the control system are obtained,and the value of each parameter in the transfer function is determined by corresponding calculation and drawing analysis.Substituting parameters into the transfer function of the system to draw a Bode plot,it can be found that the phase angle margin,gain margin,and fundamental gain of the system all meet the corresponding design requirements,thus theoretically verifying the feasibility of the control strategy adopted in this paper.Finally,based on the control strategy adopted in this paper,the corresponding MATLAB/Simulink simulation model was established for simulation analysis.The feasibility and superiority of the control strategy were verified through simulation operation,and the good anti-interference ability of the LCL grid-connected inverter system under the control strategy was verified through a series of tests.