Research On The Micro-grid Energy Management Based On Two-Stage Robust Optimization With The Consideration Of Expected Scenarios

Micro-grid refers to a small-sized production/distribution/consumption system that is a collection of distributed power sources,energy conversion devices,loads,monitoring and protection devices.It is an autonomous system that can achieve selfcontrol and management.An important means of renewable energy development and utilization.The purpose of micro-grid energy management is to make the micro-grid system run stably and efficiently by deciding and scheduling the behaviors of various components such as power generation equipment,energy storage system and response load in the micro-grid.The main challenges faced by energy management in micro-grid systems are the new energy output such as wind and solar,and the uncertainty of load,which may cause instability in the system.How to effectively deal with these uncertainties has become the important issues in energy management of micro-grid.At present,the most widely used uncertainty modeling methods are stochastic programming methods and robust optimization methods.Compared with stochastic programming,the robust optimization method does not depend on the probability distribution of uncertainty,so it has greater application value in engineering,and it has gradually become a research hotspot in the field of micro-grid energy management.The main model used in the robust optimization modeling of existing micro-grid systems is the static robust model,but since the decision can only be made once and there is no adjustment margin,the result is too conservative and cannot handle the equation constraints,making its application effect in practice greatly reduced.The two-stage robust optimization model divides the decision variables into two stages for processing.It is not only more in line with practical applications but also can effectively deal with equality constraints,so it has become a research hotspot in recent years.Because the existing classical two-stage robust optimization mainly focuses on the worst scenarios of the system under uncertainty environment,the scheduling strategy obtained by the micro-grid energy management model is still conservative,and the economic operation of the system is more affected.Based on the various uncertainties faced by micro-grid energy optimization management and the shortcomings of existing classical two-stage robust optimization,this paper proposes a two-stage robust optimization model and method based on expected scenarios for uncertainties in micro-grid systems.Modeling the effects of uncertain factors,compared with the traditional two-stage robust optimization idea,it focuses on predicting the optimal scenarios of the desired scene,while ensuring that it can be performed in any inferior scene,which can greatly reduce the conservativeness of decision-making.It can achieve the goal of enabling the micro-grid to operate safely and stably in an uncertain environment while maintaining good system economics.On this basis,considering the nonlinearity of the model and the complexity of the solution,the algorithm for solving the two-stage robust optimization model of the micro-grid based on the expected scenarios is studied,and the general algorithm step flow is given.In order to verify the effect of the two-stage robust optimization method based on the expected scenarios in the energy management of the micro-grid,this paper has considered the energy management problem of a classic island-type micro-grid and simultaneously considered to reduce the unintended interaction with the large grid.The application research of the grid-connected micro-grid energy management problem with user-side response behavior is carried out.The two-stage robust optimization energy management model based on the expected s scenarios is established respectively.Based on the general step procedure of the above algorithm,combined with the specific characteristics of the model,the specific steps and implementation details of the model solving are presented.On this basis,based on the relevant test data,this paper verifies the energy management effect of two-stage robust optimization based on expected scenarios under the two models of islanding and grid-connected,and the difference of model results caused by system parameter changes.The detailed analysis is carried out,and the expected two-stage model micro-grid energy scheduling decision results are compared with the classical two-stage model results.The experimental results show that compared with the traditional classical two-stage robust optimization model,strategies of two-stage model based on expected scenarios in micro-grid energy management model enables the micro-grid to operate more cost-effectively.This paper not only enriches the connotation of the existing micro-grid energy management field in theory,but also provides a new idea for micro-grid energy management in practical engineering.