Research On Multi-parameter Adaptive Control Of Photovoltaic Energy Storage VSG

With the massive consumption and waste of primary energy such as coal and oil,the energy crisis and environmental pollution are becoming increasingly serious in the world.The use of renewable energy for clean replacement has become an important way to solve these problems.The microgrid with distributed generation as the main body has also been widely concerned.As a small but complete power generation and distribution system,microgrid can give full play to the advantages of distributed generation and avoid the negative impact of distributed generation on large power grid.The DC power supply of microgrid must be connected with the public power grid and load through inverter.The inverter has the advantages of simple control,rapid response and good dynamic performance.But the inverter does not have the inertia damping characteristics of synchronous generator,so the stability and anti-interference of the system are low.Virtual synchronous generator control technology can not only make the inverter give full play to its original flexibility and speed advantages,but also simulate the output characteristics of synchronous generator and enhance the grid’s ability to accept distributed generation.It has become one of the research directions in the field of microgrid.This paper studies the application and improvement of virtual synchronous generator technology in optical storage microgrid system.Several conventional inverter control strategies are introduced and their advantages and disadvantages are analyzed.The mathematical model of synchronous generator is simplified and applied to VSG control strategy.A single machine VSG simulation model is built to verify the effectiveness of VSG theory under islanding and grid connected conditions.The effects of moment of inertia and damping coefficient on the output frequency characteristics of the system are analyzed.The basic principle and control strategy of photovoltaic system and energy storage device are studied.In order to give full play to the output efficiency of photovoltaic system,the maximum power point(MPPT)strategy is usually adopted.Because the widely used fixed step perturbation observation method can not fully take into account the tracking accuracy and tracking speed,this paper adopts a variable step perturbation observation method to overcome this shortcoming.According to the power balance equation of each component in the optical storage microgrid system,the coordinated control structure of each component is designed.The fixed inertia damping VSG adaptive control strategy is not continuous enough and is greatly affected by the adjustment coefficient.RBF neural network algorithm is simple,learning ability is strong and learning speed is fast.In this paper,RBF neural network is introduced into VSG adaptive control strategy for improvement.The control strategy proposed in this paper is applied to optical storage microgrid and compared with fixed parameter VSG and VSG inertia damping adaptive control strategy.The simulation results verify the superiority of the proposed control strategy.