Control Strategy for Micro-grid system in islanded mode

This paper focuses on the control strategies for islanded mode micro-grid system, which consists of wind turbines, photovoltaic panels, batteries and super-capacitors. When micro-grid is connected to the utility grid, DC-bus voltage is regulated by the inverter. And the magnitude and frequency of AC bus are the same with the grid. However when the microgrid works in island mode, DC-bus voltage must be regulated by microsouces and storages. The magnitude and frequency of AC bus are controlled by droop character of parallel inverters. Because of the fluctuation of renewable energy such as wind turbine and photovoltaic, a fast-dynamic storage system (such as super-capacity) is needed. In order to keep supplying power to the local loads in island operation, a long-term storage system (such as lead-acid battery) is needed. All of microsouces and storages are connected to DC bus by different converters. The converters must be controlled well to keep the bus voltage stable and the power flow balance. Streszczenie. W artykule przedstawiono analizę algorytmów sterowania dla mikro-sieci odnawialnych źródeł energii (turbiny wiatrowe, panele fotowoltaiczne, superkondensatory), przy pracy wyspowej. Każdy z elementów sieci podłączony jest poprzez oddzielny przekształtnik i każdy z nich wymaga odpowiedniego sterowania w celu utrzymania stabilnego napięcia szyny DC oraz mocy. (Strategia sterowania mikro-siecią w pracy wyspowej).