Reliability Analysis Of Microgrid Using Sequential Monte Carlo Simulation Techniques

Microgrid takes advantage of distributed generation and energy storage systemflexibly and efficiently as a basis of the smart grid. With the energy conservation andenvironment protection, microgrid brings a series of problems about aspects of theoperation and control, whose complex operating characteristics and flexible operationmode brings more challenges to reliability evaluation. Wind turbine generator outputtiming model, dynamic charge-discharge characteristics of energy storage system andtwo state Markov model of microgrid components is established. On this basis,reliability of grid-off and grid-connected microgrid is analyzed with chronological loadcurve based on sequential Monte Carlo simulation.Reliability evaluation characteristic of grid-off microgrid is studied and sequentialstate is simulated in islanded mode. Load shedding strategy and energy storage systemoperating strategies are proposed. Considering the factors of component states, externalinfluence and distributed generation operating characteristics, reliability evaluationcharacteristic of grid-off microgrid is studied. Taking into account of two aspects offactors including load importance and location, load shedding strategy in islanded modeis researched. This thesis introduces three kinds of operating strategies and analysisinfluence to system reliability. Strategy1is presented based on that energy storagesystem can smooth output power of wind turbine generation. Strategy2takes intoaccount of the limit of wind power penetration. Strategy3makes full use of windturbine generation to avoid maximum load shedding. The results show that sequentialsimulation algorithm with reliability evaluation characteristic can evaluate grid-offmicrogrid reliability accurately. Load shedding strategy and energy storage systemoperating strategies has important effects on system.Operation mode including grid-connected and grid-off is analyzed. Coordinationcontrol strategy in grid-connected mode and new microgrid reliability indices areproposed. Considering component fault effect coverage, operation mode is proposedbased on network traversal search. Coordination control strategy is studied based onoutput modes. The indices of average operation time to first load shedding andprobability of steady operation are proposed based on operational characteristics andswitching of different operation mode in order to evaluate continuity and stability ofsystem power supply. The results show that microgrid can improve distribution system reliability effectively. Coordination control strategy and switching of different operationmode has significant values on grid-connected microgrid reliability evaluation.On basis of microgrid reliability analysis, Sensitivity analysis of grid-off microgridreliability index is studied considering wind speed, load demand, wind powerpenetration and energy storage system capacity. Also, Sensitivity analysis of grid-onmicrogrid reliability index is studied considering capacity and failure rate of energystorage system. At last, the effects of micro-sources location on distribution systemreliability is analyzed. The results show that grid-off microgrid reliability is improvedby increasing of wind speed, wind power penetration and energy storage systemcapacity, decreasing of load demand. Grid-connected microgrid reliability is improvedby increasing of energy storage system capacity and decreasing of energy storagesystem failure rate. Then micro-sources location has influences on distribution systemreliability.