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Research On Energy Management Strategy And Control For Microgrid

Posted on:2014-07-30Degree:MasterType:Thesis
Country:ChinaCandidate:Y B QinFull Text:PDF
GTID:2272330482960895Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
As an efficient path, large-scale applications of solar and wind energy can solve the severe problems of global energy shortage and environmental degradation. Complementary microgrid consisted of photovoltaic array and wind turbine generation both can settle technical problems of the wind power and solar power large-scale access, also can give play to complementary advantages of wind and solar in time scale and geography. So the energy utilization is improved and the size of the energy storage devices are reduced which decreasing the investment cost. Reasonable and effective energy management system is the foundation which can make microgrid operating steadily, reliably and economically. This paper study and research about the topic of energy management from several aspects including features analysis and modeling for each distributed generation, structure and function of the energy management system, microgrid energy management strategy and operation control.(1) The composition and structure of microgrid are pointed out in the paper. Based on characteristics analysis, each sources’ model were set up, like photovoltaic, doubly-fed wind power generator, lithium battery and supercapacitor. Its various interface circuit are also described.(2) On the one hand, three inverter control modes are introduced in detail from two aspects of the control principle and structure. They are constant power control mode and voltage frequency control mode that are used in microgrid master-slave control and Droop control method which is presented in peer to peer control. The simulation tests were demonstrated the correctness of these control models. On the other hand, according to the research object characteristic and the given control target, the control structure of microgrid is combined with the central controller and local controllers. The energy management system proposed in this paper contain new energy power generation management, demand side management and hybrid energy storage coordination management three core functions.(3) Due to hybrid energy storage devices, a novel energy management strategy is proposed in the paper. Because of different characteristics between lithium battery and supercapacitor, lithium battery has two roles of a constant power supply or the unit that can stabilize voltage and frequency of microgrid. As constant power supply, operation plan of battery is formulated by forecasting results of new energy and load. And supercapacitor is responsible for voltage and frequency regulation due to its quick response. But considering the limited capacity, when supercapacitor is unable to content the real time power balance, lithium battery will take over supercapacitor’s duty. In strategy, energy calculation and analysis in one charge and discharge cycle is one of the important rules for new energy management and demand side management. Simulation proves the correctness and effectiveness of the energy management strategy in this paper. The strategy use the forecast data to reduce the randomness and uncertainty influence of wind and solar energy to microgrid, give full play to the fast processing system fluctuation characteristics of super capacitor, which can extend lithium battery life. On the basis of load forecasting and power prediction, load cutting plan and sources mode switching indirectly ensure the power supply reliability for important load.(4) Energy management strategy is the core of the central controller, and system management and control is needed by the local controllers that execute the instructions from central controller. According to the requirements for strategy, this paper design several local controllers, Boost converter and inverter as PV working at two different modes, MPPT and limitation, bidirectional DC-DC converter as lithium battery playing two different roles mentioned in (3), and interface converter to control supercapacitor. Through simulation testing, the local controllers is designed by the paper can meet the demand of the energy management strategy and control objectives.
Keywords/Search Tags:Microgrid, New energy generation, Energy management, Operation control, Hybrid storage devices
PDF Full Text Request
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