Research On Optimal Design Of Capacity Of Distributed Generation And Operation Strategy In Island Microgrid

The renewable energy resource such as wind energy, solar energy is abundant onisland, but its characteristic of intermittence and fluctuation brings great difficulty to powersource planning and operation.Although diesel generators have stable output characteristic,the generating cost is too much with gas emission polluting environment severely.Therefore, the configuration optimization problem which meets power supply reliabilitydemand, improves renewable energy efficiency, reduces replacement and fuel cost is to besolved. Based on the time scale of day, how to optimize diesel generator’s power output andenergy storage’s state of charge so that microgrid digests renewable energy fluctuation welland realizes economic operation is another key problem.Now, islands depend on marine cables to connect grid on land. Offshore operationsuch as fishing, dredging is liable to damage the cable. The fault location and overhauling istime-consuming and too difficult so that powr supply recovery takes long time. Therefore,realizing the seamless transfer between grid-connected mode and off-grid mode in order togurantee stable operation under various conditions is of great significance.Firstly, this paper introduces two methos, namely HOMER and mixed-integeroptimization to determine distributed generator’s capacity. Mixed-integer optimizationmethod has faster tracking speed, considers various linear constrains and convenient forsensitivity analysis but not suitable to manage non-linear constrains.Secondly, the economic operation problem considering wind,solar and load forecasterrors is studied.This paper supposes that the forecast error meets normal distribution,establishes chance constraint model, utilizes energy storage to offset inconformity betweenforecast value and actual value, and optimizes diesel generator’s power output to realizeeconomic operation.Finally, the paper discusses the control strategy for grid-connected mode, off-gridmode and the transfer between them in order to gurantees uninterruptible power at variousoperation conditions.