Photovoltatic Power System Modeling Based On Finite State Machine

As a clean,productive and non-polluting energy,the photovoltaic system of solar energy can directly transform solar energy into electric power,which is universally recognized as the ideal energy.Therefore with great prospects lying ahead in the future,it is of great theoretical and practical value to research into its control technology.At present,the designs of photovoltaic system modules are normally based on certain specialized type,which do not have universality.The problem is that the inner structure of a system needs to be comprehended before hand,making the designing process very complicated and the time limits for each step of the module are typically within miliseconds or even microseconds,which is of non practical value in terms of evaluating long-term energy yields.In response to these problems,a modeling method of building PV generating system is proposed by using the finite state machine.PV generating system is a monitoring system of complex logic,the operation process of the inverter can be divided into several different working condition,triggered by events can achieving state transition,finite state machine to meet the requirements of the application,Simulation of PV generating system depends on appropriate photovoltaic cell model and the model of the inverter.According to the principle of photovoltaic cells,this paper builds solar irradiance model and photovoltaic cell model,and analyzes the model through simulation by Simulink Model of Matlab.The result of simulation indicates that this model is efficient.We sum up the state,event,and transform relationships which may occur through analyzing the process and regulation of grid-connected inverters,and build an inverter model.Farther more,we use Stateflow Model of Matlab to simulate to analyze the interaction between the photovoltaic cells and the inverter,and perform the simulation of Photovoltaic System.The result shows that the photovoltaic system model based on finite state machine can deal with the trigger event accordingly and perform the transition of state.It also indicates that the grid-connected inverter model based on the finite state machine is feasible.When an event occurs,the state transfer faster and more accurately.User can set the parameters arbitrarily according to the situation.It can improve the ability of the system automatic control and versatility greatly.This model is suitable for calculating the energy conversion efficiency of photovoltaic system.The calculation method of energy conversion efficiency is analyzed on the basis of a certain simplification and assumption on the operation process of photovoltaic power generation system.The loss of each state can be calculated independently,and there is no need to calculate the loss of idle state.The simulation time of each state can be set according to the actual system,whether the energy output of the system is long-time or short-time,can be accurately calculated.