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Research On The Smoothing Control Of The Battery Energy Storage System In Wind-solar-battery Hybrid Power System

Posted on:2016-02-24Degree:MasterType:Thesis
Country:ChinaCandidate:Q Q SuFull Text:PDF
GTID:2272330452470712Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
The exploitation of wind and solar energy becomes more and morecentral to solve the social energy crisis and the environment pollution.However, the intermittent energy sources, such as wind power and solarenergy are easily affected by the natural power which is very intermittent,fluctuantand uncontrollable.Whensuchsourcesinlargescaleareconnectedwith the grid, the fluctuation of power will do a lot of damage. To solve thisissue, the Battery Energy Storage System (BESS) is introduced to smooththe output power of the hybrid system, called Wind-Solar-Battery HybridSystem (WSBHS). This method can improve the power quality and reducethe fluctuation if the right smoothing control strategy is carried out.In this dissertation, the short-term fluctuation of power is focused byusing the BESS. The following main points are:First, the stability of grid is discussed when the wind turbines andphotovoltaic panels are connected withthe grid. The operatingcharacteristicand the mathematical model of wind, solar and VRB is also analyzed toformulate the index of evaluating the battery working state, which is thetheory foundation of the following chapters.Second, the calculation method of low-pass filter time constant and thebattery capacity is explained by analyzing the traditional smoothing controlstrategy based on the principle of low-pass filter. What’s more important, anew smoothing control strategy based on State of Charge (SOC) of batteryis executed to change the time constant of the low pass filter is proposed,which take the SOC into consideration and avoid charging or dischargingtoo much. Besides, the capacity of self-adapt SOC based on the fuzzy control is added into the strategy, which resulted in the enhancing ofcontrolling power fluctuation.Finally, the Simulink model of WSBHS is established to verify thesmoothingcontrol strategybased on SOC and the self-adapt fuzzycontroller.And it turns out that the proposed method can not onlyreduce the fluctuationof the WSBHS, but also improve the service life of the battery throughkeeping the SOC in a proper range.
Keywords/Search Tags:Wind-Solar-Battery Hybrid System, BESS, SmoothingControl, Self-adapt SOC, low pass filter
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