The Inverter Circuit Design And Grid-connected Implementation Of 100kW PV Grid-connected System

The demand for power energy is increasing with the rapid development of the economy,and the development of new energy has become an urgent demand at home and abroad.Photovoltaic(PV)grid-connected is an important use of new energy,and inverter is the core of energy conversion and control in the PV grid-connected system.Based on the actual engineering needs of PV grid-connected,aiming at the three-phase photovoltaic grid connected system of 100 kW,we have studied and analyzed the selection of PV modules,the development of inverter circuits and the implementation of grid connection.The main works are as follows:Firstly,the composition and classification of photovoltaic power generation system are explained.The topological structures of grid connected photovoltaic power generation system inverter main circuit are described.Different output filter modes for grid connected PV inverter are introduced.And the LC type filter is selected as the filter link of the main circuit,the control methods of photovoltaic grid connected inverter and the related control technology are analyzed.The key technology of grid connected photovoltaic system is discussed.The current controlled voltage source type inverter is selected as the inverter of the main circuit.Secondly,a method based on piecewise linear interpolation and least squares is proposed to detect the inconsistency of PV cells,and its effectiveness is verified by simulation.The inconsistency detection method of piecewise linear interpolation and least square method proposed in this paper is more effective and accurate through the analysis.The signal conditioning circuit for sampling filtering,phase shifting and biasing of the voltage and current signal is designed.The actual circuit is constructed to verify the effectiveness of the designed circuit.In order to protect IGBT from damaging due to abnormal conditions,the drive circuit,overcurrent,overvoltage,over-temperature and short-circuit protection circuit are designed for inverter.Finally,the single stage topology structure is selected for the main circuit.The current deadbeat control mode is used as the grid connected control mode.The detailed main circuit is designed,including the main circuit implementation,power device selection and parameter design of DC-link capacitor and filter circuit design.The simulation is used to verifying.Aiming at the heat dissipation of three-phase photovoltaic inverter grid connected system,the performance index of 100 kW three-phase photovoltaic inverter grid connected system is obtained according to the calculation of thermal model,and the specific type of the required radiator is determined.The double loop control strategy with voltage PI outer loop and deadbeat control inner loop is selected to achieve efficient operation and fast response of the system.The simulation with PSIM verifies the feasibility of the scheme.