Research On Grid-Connected/Off Switching Control And Dispatch Strategies Of In Microgrid Including Energy Storage System

Microgrid is an important form to reduce the interaction between high-density divided generation and power grid.It is an important way to realize the self-healing,user side contact and demand side response of modern smart spread network.It has the dual functions of carrying energy and information.It can improve the interaction mode between divided generation and distribution network,promote the full application of various types of energy,and accelerate the “carbon peak” and “carbon in” process.However,due to the obvious variation characteristics of divided generation,the microgrid with low inertia features is prone to be affected by uproar,resulting in a variety of power quality and operation stability problems,so there are still many control problems,such as parallel/off grid switching control,power sharing control,voltage and frequency variation repression control.In this paper,energy storage is applied to the smooth switching control of microgrid parallel/off grid and the economic optimization interaction between microgrid and grid.Firstly,this paper outline the development and research status of microgrid in detail,expounds the technical difficulties and related solutions of microgrid,and points out the application prospect of energy storage in the stability of microgrid voltage,frequency and power variation,and the economic interaction between microgrid and power grid.Then,the principle,essay type and output characteristic modeling of wind power generation and photovoltaic power generation in microgrid are analyzed,and the composition structure of energy storage system is introduced.Furthermore,the operation control strategy of energy storage in the process of grid connected mode,off grid operation mode and parallel/off grid dynamic switching is deeply studied,and the numerical modeling and control parameter design of energy storage bilateral converter control system under PQ control and constant voltage /constant frequency control are analyzed.Aiming at the problem of nonparallel vibration in the process of switching from off grid to on grid,a pre synchrony control strategy and related operation logic control process are proposed to achieve smooth switching.Pretense experiments verify the regulation effect of energy storage on microgrid voltage and frequency in grid connected mode,off grid mode and parallel/off grid dynamic switching process.Finally,a simple and effective increase formula is proposed for the energy storage participating in the economic optimal dispatch control of microgrid,which amends the energy storage output dispatch instruction,makes full use of the energy storage and energy support function of energy storage to a certain extent,and achieves the purpose of economic power consumption of microgrid by actively dispatching the output of energy store at different electricity prices.Simulation results verify the effectiveness of the proposed algorithm.