Research On The Control Strategy Of The Microgrid

In today’s world, the depletion of global fossil fuel reserves is posing achallenge to the growing global energy demands of the day. Therefore, exploitingthe renewable energy resources to meet the electrical energy requirements of themodern world has become increasingly important. Although the use of large-scalerenewable energy will bring a lot of the unknown problem to the power system, theproposal of the microgrid’s concept provide a new approach to the use of renewableenergy. The microgrid can operate on grid connected and islanded mode. In adifferent operating mode, renewable energy requires different control measures tomeet the security and stability of the entire system. Therefore, under the differentoperating modes of the microgrid, some renewable energy research about differentcontrol measures to minimize the effect of the power system which consistent of theintermittent renewable energy.First this paper models common renewable energy power plant includinghydropower plants, wind farms and photovoltaic plants. For the hydroelectricplant, the focus of research is hydroelectric power plant parameters for the systemprimary frequency performance, in order to rationalize the main parameters of theselected hydropower plants. For the photovoltaic plants, modeling photovoltaicarray model and the research is the characteristic curve of photovoltaic cells indifferent environments. For the wind farms analysis of the mathematical model ofthe doubly-fed wind power generation system module and research on double-fedwind turbine operation curve in different wind speeds, to establish the theoreticalbasis for the establishment of subsequent wind farm control strategy.Secondly, the established microgrid contains renewable energy power plantsand battery energy storage system and reactive power compensation system(D-STATCOM). The approach based on the application of frequency constraint;determine herein to establish the microgrid of the largest capacity of the intermittentenergy. This paper presents an microgrid cooperative control strategy, its structureis the double-layer of cooperative control: The primary control is the battery energystorage system, secondary control is a microgrid management system (MMS);Primary control ensure that the frequency of the microgrid is within the acceptablerange, secondary control ensure the largest spare capacity in the microgrid. Thoughtthe study of the different micro-source local network in the microgrid, Designed themicrogrid management system, to implement the regulation different micro-sourcein the microgrid. The proposed control strategy was simulated and analyzed,simulation results show that the cooperative control strategy has good dynamic performance, and effectively improve the quality of the system’s frequency, whileensuring the quality of power supply requirements.With solving the problem that the large affect of the microgrid reconnection tothe grid, this paper proposed active synchronizing control strategy of the microgrid.According to the dynamic characteristics of the different micro-source in themicrogrid, the frequency deviation, phase angle deviation and voltage deviation arerespectively assigned to the different micro-source regulation. This way can quicklyadjust the running state of the microgrid. It closed the connected switch, after thesethree deviations meet the synchronizing criteria. Active synchronizing controlstrategy of the microgrid compare with the method of the directly closed switchthrough simulation, simulation results show that this method can effectively reducethe impact of frequency shock when the microgrid reconnection to the grid andsuppress systems concussion. Lastly, the microgrid on grid connected mode,different micro-source control strategy is proposed in the microgrid, to achievecontact line that between the microgrid and the grid power constant. When there issufficient energy in the microgrid, the energy is injected into the Grid by themicrogrid, the microgrid is equal to constant output power of the power station; Theenergy in the microgrid is insufficient to meet its own internal demand, the Grid hasto feed to the microgrid energy, then the microgrid is equal to constant load, By theabove regulation to reduce the impact of intermittent renewable energy to the powersystem.This paper is supported by the National High Technology Research andDevelopment Program Project (863Program)(NO.2011AA05A105).