Research On Power Control Strategy Of Photovoltaic Power System

With the increasing depletion of global fossil energy and the rapid development of photovoltaic power generation technology,the proportion of photovoltaic energy in China's energy structure has increased year by year.PV arrays,as a power generation devices of photovoltaic power generation systems.is used to come true safely and efficiently maximum output power of photovoltaic arrays,is the key to improving the economical efficiency of photovoltaic generation power systems,while photovoltaic inverters convert input DC power into output AC power.The process is the core component of photovoltaic generation power system,and its performance determines the power quality of the inverter.This paper mainly focuses on the research contents of PV array modeling,maximum power tracking,DC inverter control strategy and PI parameter optimization.The main research contents of this article include:(1)The paper explains the design principle of photovoltaic generation power system,and gives the parameter design method of each key part of photovoltaic generation power system,and introduces the theory and design principle of inverter control strategy in detail,simplifies the photovoltaic inverter control using coordinate transformation.In the process,the phase angle ? of the rotating coordinate system is accurately calculated by the SPLL algorithm.Various commonly used SPWM waveform modulation methods are analyzed and the harmonic distortion ratios of various methods are compared.The particle swarm optimization algorithm is used to optimize the parameters of the PI controller.method.(2)The paper analyse the circuit characteristics of photovoltaic cells.,the simplified mathematical model based on the characteristics of photovoltaic cells was obtained,and the Simulink simulation model of photovoltaic cells was built.The output characteristics of photovoltaic cells under different temperature and light intensity conditions were simulated and verification.The principle of maximum power tracking of photovoltaic cells is studied,and the advantages and disadvantages of various traditional MPPT algorithms are compared.The traditional disturbance observation method is selected and its step length disturbance is improved.The simulation results show that variable-length disturbance observation algorithm can be more quickly stabilize to maximum power point.(3)The paper explains the common PV inverter control strategy.The dynamic system modeling of the inverter control process of photovoltaic generation power system in standalone operation mode and grid-connected operation mode is performed.The photovoltaic generation power system selects the V/f inverter control strategy in independent operation mode.The simulation results show that the inverter control algorithm can output the stable AC power,and the photovoltaic generation power system adopts the PQ inverter control strategy in grid-connected operation mode.The simulation results show that the inverter control algorithm can output stable constant power and high-quality grid-connected power.