Autonomous Control Of Multi-Microgrids With Cyber Physical System Mode

Due to increasing concern about the environment and skyrocketing cost for fossil fuels,low carbon economy,energy diversity and sustainable development have been the focus of power industry.On this background,renewable energy distributed generation has gradually been an effective important supplement form of conventional centralized generation.Microgrid is an effective way to support distributed generation integrated into,and it has become a hot topic that how to make full use of renewable energy,improve power quality and guarantee reliability of power supplement through flexible control technology.While Microgrids process some shortcom:ings that limited storage,low resilience and low robustness,multi-microgrid has been proposed.In order to realize the autonomous and coordinated operation of multi-microgrid,the distributed resource need to be cooperative optimized,which should be supported by the power cyber-physical system(CPS).The Multi-microgrid CPS includes the ability of perception and control to physical devices,and could promote the efficient utilization of bidirectional information flow.Given these backgrounds,this dissertation mainly focus on multi-microgrids CPS with a high penetration of renewable energy generators and aims to analyze and establish autonomous and coordinated control system for future multi-microgrid CPS,which enables high penetration renewable energy generators to participate in the grid as well as to guarantee the security,reliability,efficiency and economy in the operation of future multi-microgrid.The detailed contents of the dissertation are as follows:Firstly,with respect to the research of autonomous interconnection of multi-microgrid,the dissertation proposes a distributed estimation method to compute the estimate of difference between distributed power output and adjustable load value through the information sharing between adjacent microgrids.The interconnectivity of multi-microgrids is analyzed to ensure the secure operation after the grid-connection to the distribution network by using the distributed local communication net topology.Simulations are presented to verify the proposed method can accurately judge whether the multi-microgrid cluster meet the interconnection condition or not under no-global communication,communication failure or latency.Secondly,with respect to the research of improving the frequency response to support the interconnection of Multi-microgrid,the dissertation proposed a rmodified conservation voltage reduction method to improve the frequency response when dealing with the problem of interconnection of Multi-microgrid.The issue of dynamic stability is especially acute in microgrids with high penetrations of inverter-connected generation,and a correspondingly low system inertia.This problem can be leveraged by using modified conservation voltage reduction method without using the method of over sizing the rotating generators.This method can reduce the capital and improve the stability of Multi-microgrid.The effectiveness of the proposed strategy is illustrated through simulations on the IEEE 123-bus test system.Thirdly,with respect to the research of emergency power dispatch of Multi-microgrid,the dissertation proposed a Voronoi based distributed strategy to address emergency power dispatch problem associated with autonomous microgrids.In particular,our proposed scheme translates power management problem into classical coverage control problem,where each generator is treated as a Voronoi cell and thrives to compensate for the time-varying demands and unknown grid failures.We demonstrate that the proposed method takes full advantage of the nature of Voronoi cells,such as adaptiveness to uncertainty and robustness to distributed information exchange,and is capable of converging to desired distribution,such as the average power setting of each unit in microgrid in spite of power emergencies.Simulations results on IEEE 57-bus system verified the effectiveness of the proposed approach.