Research On Renewable Energy Sources Into Electric Power System

Significant scientific and technical problems and wide difficulties are involved in renewable energy source technologies.The maximum power point tracking (MPPT) algorithms in grid-connected photovoltaic generation system and in grid-connected PMSG Wind Generation System, along with the optimal power energy management (PEM) strategy for grid-connected Microgrid, were studied in this paper. The main work was presented as follow:(1) Background and significance of study on renewable energy source, as well as the superiority of renewable energy source integration into power systems, were in introduced. The developments of renewable energy source all over the world are reviewed. And merits and demerits of traditional MPPT algorithms in grid-connected photovoltaic generation system and in grid-connected PMSG Wind Generation System, together with merits and demerits of traditional optimal power energy management strategies for Microgrid, were also summarized in this paper.(2) The application of fuzzy control methods into MPPT algorithm in grid-connected photovoltaic generation system and MPPT in grid-connected PMSG Wind Generation System were studied. Following the basic introduction of fuzzy control algorithm, the MPPT traditional algorithms and fuzzy control algorithm for those two systems were introduced and analyzed in details. Four performance-indexes of MPPT were also proposed in this paper. Cases studies verified that fuzzy control method proposed in this paper is superior to traditional methods.(3) Multi-time scale power energy management strategy for grid-connected Microgrid was proposed. The mathematical models of renewable energy source used in Microgrid were established, including mirco-turbine, fuel cell, and diesel generator. The proposed multi-time scale power energy management strategy includes three layers:1) unit commitment (UC) layer or day-ahead scheduling layer,2) economic dispatch (ED) layer,3) real-time dispatch layer or AGC layer. In the day-ahead scheduling, optimal on/off states of controllable micro-sources in each time interval of whole day are arranged through the day-ahead model. In the economic dispatch, the on/off states of controllable micro-sources from day-ahead scheduling is adopted, the output power of each controllable micro-source and storage device are adjusted. In AGC real-time dispatch layer, according to the real-time data of PV, WT, and Load in second intervals, energy storage output was adjusted, in order to smooth the power fluctuation in the internal microgrid network and the exchange power would be constant between the main grid and microgrid, which could reduce the impact on main grid from microgrid and serve for economic dispatch of main grid. Finally, the cases studies verified the rationality and validity of the proposed PEM strategy for grid-connected microgrid.