Research On Modeling And Frequency Regulation Strategy Of Photovoltaic Power Generation System

Photovoltaic solar energy is widely used as a recyclable natural resource,but photovoltaic power generation is often random and fluctuating.As its installed capacity continues to increase,the impact on the stable operation of the power grid is becoming more and more serious.Improve the photovoltaic power generation system The ability to actively participate in grid frequency regulation is imminent.In order to balance the frequency response and power generation efficiency at the same time,a new photovoltaic power generation strategy is proposed by adopting variable power point tracking and super capacitor participation in frequency modulation.The main research contents of this paper are as follows:First,establish a mathematical model of the photovoltaic power generation system.In terms of mathematical modeling of photovoltaic power generation arrays,a 5-parameter diode model is used,and the parameters of key points are corrected.In terms of photovoltaic array power tracking,when photovoltaic power generation systems participate in grid frequency modulation,the system needs to work at different active power points,and an adaptive voltage step variable power tracking algorithm is proposed.In terms of photovoltaic inverter control strategy,a double closed-loop control model of synchronous rotating coordinate system is established.Among them,the outer loop uses voltage control to stabilize the DC bus voltage,and the inner loop regulates the active and reactive current input to the grid and the decoupling of the current.Second,the control principle of synchronous generator technology is introduced.The photovoltaic virtual synchronous machine adds frequency deviation negative feedback and frequency differential negative feedback to the frequency modulation control equation,so that the output reference power of the photovoltaic system is composed of inertia support power and primary frequency modulation power.These two types are further analyzed.Power participates in the characteristics of frequency modulation.Then the photovoltaic array power tracking algorithm is added to the inverter control,and the three-loop structure of the typical photovoltaic inverter control strategy is proposed.Third,combining the advantages of active standby frequency modulation strategy and configuration of energy storage frequency modulation strategy,an innovative frequency modulation strategy based on variable power tracking and supercapacitor energy storage coordinated control is proposed.The frequency modulation strategy makes the system work normally in the maximum power tracking mode.When the load suddenly decreases or the frequency increases suddenly,the variable power tracking algorithm is started,so that the output power of the photovoltaic power generation system is the reference power value,so as to ensure the rapid adjustment of the frequency;When lowering,the supercapacitor device of the photovoltaic DC side bus is controlled by the bidirectional DC converter to participate in frequency modulation,providing primary frequency modulation power and inertia support power for the system.Comparing the economic benefits of configuring the energy storage frequency modulation scheme and the active backup frequency modulation scheme,the average annual investment amount for configuring the energy storage device is only half of the loss caused by the reserved standby power.In addition,because the supercapacitor energy storage device participates in the frequency modulation process,the optical storage system can quickly provide inertia support power,and the technology is more complete.Finally,the MATLAB/SIMULINK platform of MathW orks is used for simulation.The simulation results show that the participation of photovoltaic system in frequency modulation can alleviate frequency fluctuations caused by load changes,which can replace the frequency modulation effect of synchronous generators to a certain extent and reduce the standby capacity of synchronous generators.The optical storage coordinated control scheme proposed in the article can realize the coordinated operation of the optical storage system to reduce the positive/negative deviation of the steady-state frequency,and can suppress the rapid frequency fluctuation.Whether in terms of economic benefits or frequency adjustment,the optical storage coordinated control scheme is significantly better than the active backup scheme.