Research On Single-phase Optical Micrograph Network Based On DC Voltage And Power Control

Distributed power generation has become an important way to obtain new energy sources in the global energy crisis environment,and it is an indispensable part of the research on inverter control of power electronic equipment.PWM inverter with its DC side voltage control,AC side of the current sinusoidal good,AC side power factor control and other advantages more and more favorable.Single-phase photovoltaic grid-connected control is widely used in low-power photovoltaic applications,so the control technology of single-phase inverter and stable and connected network has important practical significance.(1)Based on the structure of the two-stage single-phase photovoltaic grid-connected power generation system adopted in this paper,bulding a photovoltaic cell model;The perturbation voltage method is applied to realize the Maximum Power Point Tracking of photovoltaic cells.A mathematical model of single-phase inverter in ap coordinate system and dq coordinate system have been built;and design of LC filter circuit.The model is very important to establish the system device selection and parameter setting.(2)The control strategy of grid-connected inverter based on virtual flux orientation and load power feedforward is proposed.There are many areas where traditional voltage vector orientations can be improved.Aiming at the problem that the internal loop PI controller can not achieve the steady-state error tracking problem,the quasi-proportional resonance(qPR)controller has been put forward,The parameters of the inner loop controller are designed by the inverter model,and the simulation and experimental results show that the current can not achieve steady-state error tracking;From the point of view of simplifying the complexity of the system,the purpose of eliminating the DC side voltage sensor is realized by using the single-phase virtual flux orientation method.The directional method can effectively connect the network.DC bus voltage disturbance easily leads to system instability,aiming at the problem that the DC bus voltage is disturbed under the condition of load disturbance,the load power feedforward method is used to verify that the method can effectively suppress the DC bus voltage fluctuation due to load disturbance.(3)The power control strategy of single phase inverter is proposed.Aiming at the problem that the single-phase inverter has only a single AC variable and the virtual quadrature quantity needs to be constructed.The method of constructing the method is analyzed by using the second-order generalized integrator.Based on the two-phase virtual system,the single-phase power prediction model under the general criterion of instantaneous power theory and prediction algorithm is deduced.The control strategy is applied to the single-phase inverter by simulation.The result shows that it can realize the unit power factor,and it can realize independent control of active and reactive power.(4)The experimental results can be proved on the simulation platform based on dSPACE.The experimental results can prove the validity of the proposed method and have some engineering significance for distributed PV grid-connected power generation.