Research On Security Operation Strategy And Platform Validation Of Islanded Microgrid Clusters Under The Influence Of Power Supply/Load Disturbances

At the 75 th Session of the United Nations General Assembly in 2020,the goal of emission peak and carbon neutrality was proposed firstly in China,and to achieve that,China has been accelerating the development of new energy industry to further reduce the reliance on traditional energy.As a typical scenario of new energy application,microgrid has attracted wide attention.The application and development of microgrid has been approaching maturity,but the unstable conditions may still exist when operating off-grid.Being the extension of microgrid,islanded microgrid clusters not only have the advantages of high autonomy,high reliability and significant economy,but also can meet the personalized needs of users.It is important to study the operation and control technology of islanded microgrid clusters because they can coordinate the power output and maintain the stability of voltage and frequency of sub-microgrid,and when source/load disturbance occurs,islanded microgrid clusters will put forward new requirements for system operation and regulation.To realize the safe and stable operation of islanded microgrid clusters,this paper mainly focuses on the stable control strategy of system voltage and frequency under source / load disturbance.Firstly,the secondary control strategy of islanded microgrid has been designed based on the stability analysis of microgrid clusters and multi-agent consistency algorithm.Then,the islanded microgrid clusters system under source/load disturbance has been further studied,and the coordinated control strategy of that has been proposed,while the software and hardware experimental platform of the islanded microgrid clusters system being designed and the effectiveness of the coordinated control strategy being verified.(1)Analyzing stability and proposing coordinated control strategy for islanded microgrid clusters under source/load disturbance.Firstly,considering the voltage control,frequency control and common coupling point voltage of the islanded microgrid clusters,analyzing the influence of source/load disturbance on it,the autonomous operation control strategy of the islanded microgrid clusters was proposed to realize the stable control of voltage and frequency.Secondly,considering the system time delay caused by lines and equipment in the operation of the microgrid clusters,and based on the multi-agent consistency algorithm,the microgrid secondary coordinated control strategy has been proposed to improve the stability of the islanded microgrid clusters under the source/load disturbance by regulating the voltage and frequency.Finally,in view of the power mutual assistance among microgrid clusters,the coordinated optimization function of islanded microgrid clusters has been designed to enable the rapid restoration of system voltage and frequency stability through inter-microgrid coordinated control when a source/load disturbance occurs in one of the microgrid clusters,reducing the system operation cost while verifying the effectiveness of the proposed strategy through simulation.(2)Designing and simulating the software and hardware of the system based on the coordinated control strategy of islanded microgrid clustersIn order to accurately verify the effectiveness of the coordinated control strategy,an experimental platform of islanded microgrid clusters system composed of three sub-microgrids has been built.Considering the influence of climate on new energy generation,the system capacity configuration of islanded microgrid clusters has been designed and analyzed.In the hardware platform,the information communication and PLC control among modules have been designed and developed to ensure the reliable communication and stable operation of distributed power supply among microgrids.To facilitate the simulation control analysis,the mathematical models of distributed power supply,loads and inverter modules such as photovoltaic,fan and energy storage in the sub-microgrid have been sorted out and constructed,and the coordinated control strategy of the islanded microgrid clusters has been designed and developed in the intelligent control module of the management platform.Finally,the effectiveness of the coordinated control strategy for islanded microgrid clusters under source/load disturbance has been verified with hardware and software experiments under different scenarios.