Research On Power Restoration Of AC/DC Hybrid Distribution Network Based On Semi-definite Programming

With the development of power systems,traditional distribution networks need to be upgraded to meet the demands of new and distributed power supplies.With the access of Electric Vehicles(EVs),Distributed Generations(DGs)and DC loads,traditional AC distribution network would be too complicated to be managed.Moreover,with multiple types of electrical converters involved,the complexity of the distribution network has increased again,decreasing the safety and reliability of the system.At the same time,with the development of new power electronic components such as VSC-HVDC converters and Soft Open Points(SOPs),the investments and implementations of hybrid AC/DC distribution networks have become technically and economically possible.Hybrid AC/DC power distribution systems have been proved to be with advantages of safety,reliability and economy.However,the research on DC power distribution made at home and abroad is still in their initial states,and the related fault recovery and protection techniques for hybrid distribution network is still blank.In order to verify the feasibility of hybrid AC/DC distribution system,this paper focuses on solving the semi-definite programming model of AC/DC distribution network power supply recovery problem.According to the unsolved issues from multiple current researches,this paper focus on the distribution power supply recovery problem of AC/DC hybrid networks after local failures.In order to improve the efficiency of the solution,one of the most important methods in the field of optimization developed in recent years,the Semi-Definite Programming(SDP),is used to fulfill optimization calculation.By introducing the relevant model of semi-definite programming,combining the original dual interior point method and the specific solution process,an optimization model for power supply recovery of AC/DC distribution network based on topology parameters is established.Combined with the semi-definite programming model,the sparse matrix technique is applied to solve the problem,which greatly improves the efficiency of the solution.Through multiple study cases of hybrid AC/DC distribution networks,efficient power restoration strategies are proposed and SDP method is carried out and analyzed.Finally,the interior point semi-definite programming algorithm is applied to solve the problem.In order to improve the data acquisition accuracy after the distribution network fault,combined with the weighted least squares estimation criterion,the system’s state estimation calculation is carried out by means of the limited real-time measurement data in the system to eliminate the error messages caused by data interference.Applying the least squares estimation based on the semi-definite programming,the error between the measured value and the true value is obtained and corrected.The calculation and analysis of the AC and AC-DC hybrid examples demonstrate the correctness of the proposed method.The research results show that the application of semi-definite programming to solve the distribution network fault recovery problem,has certain advantages in terms of calculation time,recovery degree and solution accuracy.The power restoration problem based on real-time measurement about data accuracy has higher performance in practical applications.