Research On Microgrid Economic Dispatch Model Based On Energy Storage Optimization

The number of distributed generators using wind,solar and other renewable energy to generate electricity is increasing.The distributed generations and nearby loads constitute a miniature power generation and power supply system.It is called microgrid.Microgrid technologies are aim to solve the problem of renewable energy access to large power grid.As a new way of power generation and renewable energy access to common grid,the economic dispatch of microgrid has been a subject of great concern.Based on the analysis of the operation characteristics of Distributed Genetators(DGs)and batteries,this paper presents an economic dispatch model for a practical microgrid.The objective function of the model takes into account the service life of the batteries and the influence of the common grid’s peak-valley price.The service life of the batteries is related to its charging and discharging process.Based on the output prediction of distributed power supply and the load forecasting of microgrid,this paper improves the batteries’ charging and discharging strategy.The optimization strategy is to make use of the surplus power of the DGs to charge the batteries as much as possible,so as to reduce the cost of using the common grid to charge the batteries.At the same time,in order to prolong the service life of the batteries,their charging and discharging times during a short time should be controlled.The main work of this paper is as follows:1)The cost model of the battery in the economic dispatch of microgrid is improved.The single cost of charging or discharging of the batteries is calculated by the ratio of the absolute value of charge or discharge to the total throughput of the batteries.This method has shortcomings.This paper calculates the cost by the ratio of the 2 times value of discharge power to the total throughput.It can overcome the problem that when the batteries charge state is low,and the charging power is too large,resulting in higher charging costs and microgrid has to reduce the charging power.At the same time,on the basis of the distributed power supply and load forecasting,the charge and discharge strategy of the battery is optimized through the power balance between the output and the load.The basic idea is as much as possible to use renewable energy electricity to charge the battery,and in the peak period and distributed power supply is insufficient,as much as possible to use batteries storage energy to supply power to load.In addition,the service life of the storage battery can be improved by controlling the number of small power charging or discharging of the battery pack.2)According to the relevant data of the output power loss rate and the output loss rate of the inverter,the cost model of the wind turbine and photovoltaic power station is established.These two models are applied to the microgrid economic dispatch problem when the distributed power supply is larger than the load.3)The objective function of economic dispatch of microgrid is realized.Based on the comparison of the distributed power supply and the microgrid load,the objective function is divided into two sections.When the output power of distributed power supply is greater than that of microgrid,the wind power and the minimum output power loss are the target.When the output is less than the load need to provide additional power batteries or the public grid,the minimum cost of micro grid as the scheduling target.4)This paper uses particle swarm optimization algorithm to solve the economic dispatch model.it provids the economic dispatch results of each unit in microgrid and a brief analysis.Economic dispatch model for the actual situation of each DG in micro grid based on the influence of life loss of battery and the public power grid peak-valley price can be more comprehensive and effective implementation in micro grid with the lowest cost target.By using the particle swarm algorithm for solving the economic dispatch model,and analyzing the economic dispatch results,the model has certain reference significance which can provide strong guidance for the planning and control of microgrid.