The Research Of Control Strategy Based On Low Voltage Looped Microgrid

This thesis was supported by Natural Science Foundation of Chongqing（CSTC2009BB6190） and independent research project of State Key Laboratory ofPower Transmission Equipment&System Security and New Technology（2007DA10512711209）.Microgrid is independent controlled system which consists of DG （DistributedGeneration）、local load and energy storing device. When the network structure ofmicrogrid containing various DG changes, how to make effective control of DG, DS,local load and switch in microgrid is the key for the safety, stability and reliableoperation of microgrid to ensure that it can meet the local users’ demand in differentrunning status. Thus, the research on hooped and looped microgrid containing variousDG has important significance. This thesis focus on the simplify and combination in theprobable running status of looped microgrid according to the local power demand, andanalyses the status of kinds of trigger events which is displaced by the way ofincidence matrix in looped microgrid. Furthermore, it designs the control strategy ofsynchronous reconnection in looped microgrid. Main work of the thesis as follows.①This thesis researches the several typical micro-source (such as wind power,photovoltaic, etc) model of the multi-energy hybrid microgrid, anglysis the dynamicresponse characteristics, details the microgrid control strategy and the scope ofapplication②It studies the MGCC （Microgrid Central Controller） and local controller oflooped microgrid which is based on two hierarchical structures. The upper strata is thatthe MGCC offers active and reactive power set value to DG and DS using the collectedthe load information、the fuel condition of DG and DS and running state in order toachieve optimal power splitting and microgrid state transition and the control oftangential load. The under strata which is the local control unit executing specificoperating instructions of MGCC contains MC （Micro source Controller） and （LoadController）.③In the looped microgrid the possible running status are simplified and combinedaccording to the local power demand. The state transition process of kinds of triggerevents in looped microgrid is analyzed. Facing complicated status in looped microgrid,the mode incidence matrix using to dispose the complicated status transition is put forward which fully reflects the flexibility and stability of looped microgrid.④The Matlab/Simulink simulation software is used for analysis of the dynamiccharacteristics of typical radiated microgrid. Simple looped microgrid model is built onthe basis of radiated microgrid. According to the simulated analysis of looped microgrid,the flexible switching characteristic is verified. The scheme of synchronous controlstrategy in looped microgrid is put forward, and its feasibility is verified according tothe simulation.