Research On Single-phase Grid-connected Inverter Based On Quasi-PR Digital Controller

With the energy depletion and environmental degradation,the pace of exploration of new energy power generation will be faster and faster.Then,the grid-connected inverter is the core of the new energy power supply and network.The current harmonics of the new energy distributed power supply pollutes the power grid and affects the grid operation of the inverter.Therefore,it is very important to study the control strategy of the inverter current.In this paper,the digital PR control strategy is selected to realize the no static tracking of the reference signal,reduce the total harmonic distortion of the network current,and improve the anti-grid interference of the system.A 1kW single-phase grid-connected inverter is developed.In this paper,firstly,the grid-connected inverter system is introduced synoptically.The SPWM modulation technology,filter type and digital phase-locked loop are introduced in detail.Mathematical model of single-phase grid connected inverter based on state space averaging method.The input current expression based on PI,PR and quasi-PR control grid-connected inverter is given.The control performance of the controller in the grid-connected inverter is analyzed from three aspects:controller characteristic,system steady-state error and anti-grid interference.The quasi-PR controller can achieve the zero-error tracking of the reference signal and the performance of the strong anti-grid interference.On the basis of the theoretical analysis,the calculation of the main circuit,filter,driving circuit,control circuit parameters and the selection of the device are completed.The implementation of digital SPWM and digital phase-locked loop is briefly introduced.Finally,the experimental prototype of the grid-connected inverter is built according to the calculated parameters,and the experimental waveform is obtained by debugging the experimental prototype.The incoming current completely tracks the grid voltage waveform.Grid-connected inverter is stable and grid-connected and to achieve the desired effect.