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Reactive Power Optimization Of Islanded Microgrids

Posted on:2020-08-13Degree:MasterType:Thesis
Country:ChinaCandidate:Y D LuFull Text:PDF
GTID:2392330578955019Subject:Power system and its automation
Abstract/Summary:PDF Full Text Request
Reactive power optimization can optimize the distribution status and voltage quality of various reactive power devices in the mesh microgrid as an optimization method.Due to the non-linear characteristics of AC power flow equation and the discreteness of reactive power compensator variables,reactive power optimization belongs to non-convex non-linear programming with discrete variables.Therefore,convex relaxation of power flow equation is often used in practice,and then a mature commercial solver is used to solve it.Because the convex relaxation of power flow has strong pertinence to the network topology,the necessary and sufficient condition for obtaining feasible solution for ring microgrid is that the local and cyclic conditions of the network should be satisfied at the same time.It is of great significance to study the convex relaxation of power flow and the optimization problems derived from convex relaxation for the operation of circular microgrid.The main contents of this paper are as follows:1.According to the BIM(Bus Injection Model)framework,the triangular function relaxation and McCormick relaxation of phase difference constraints are performed to establish the basic SOCP reactive power optimization model,and the initial values are obtained.The convex difference equation and the modified equation are used to improve the SOCP model and improve the quality of the solution of the SOCP model.2.Based on the above reactive power optimization model,the discrete variable of reactive power compensation is introduced to rationalize the reactive power compensation mode.According to the characteristics of microgrid,multiple objective functions are reasonably set up,multi-objective function model is solved by using-constraints,and optimization scheme with high satisfaction is obtained by using fuzzy satisfaction function.3.The uncertainties of renewable energy output in reactive power optimization problem are solved by using the adjustable robust optimization method.We divide decision variables reasonably and establish two-stage adjustable robust model,which is solved by C&CG method.In order to verify the validity and accuracy of the models proposed in this paper,33-nodes distribution system is modified slightly,and various reactive power compensation devices are added to obtain a general ring topology microgrid test system.In this paper,a large number of simulation experiments are carried out on this system.The simulation results show that the proposed improved SOCP reactive power optimization model has high accuracy in the case of ring microgrid system.Moreover,the calculation efficiency is improved while the accuracy is guaranteed,which is superior to the SOCP reactive power optimization model for general distribution network.The proposed multi-objective function and constraints have good applicability for reactive power optimization decision-making in microgrid,and a "satisfactory"optimization decision can be obtained by using fuzzy satisfaction degree.The proposed robust reactive power optimization can characterize the uncertain output of renewable energy,maintain the robustness and feasibility while minimizing the objective function value in the worst case.
Keywords/Search Tags:microgrids, reactive power optimization, SOCP relaxation, mul-objection, adjustable robust optimization
PDF Full Text Request
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