電池儲能系統應用於微電網之自動發電控制及基於螢火蟲最佳化演算法之頻率預防控制

Abstract

本論文目的在於設計微電網中電池儲能系統(Battery Energy Storage System, BESS)的自動發電控制(Automatic Generation Control, AGC)策略，來控制電池儲能系統的輸出功率，以改善風速變動時所導致的風機輸出波動與負載在較小擾動下對於微電網系統的動態頻率響應所帶來的不良影響。 本論文另一個貢獻是，當微電網遭遇大型負載擾動時，使用本論文提出的預防控制(Preventive Control)方法，利用電池儲能系統反應速度快速的特性，結合螢火蟲最佳化演算法(Firefly Algorithm, FA)設計出電池儲能系統最佳輸出功率大小及最佳充放電時機等相關參數，在確保電池儲能系統的電量狀態 (State of Charge, SOC)充足情況下，能夠防止系統頻率過低觸動低頻卸載電驛造成微電網中用戶停電的情況發生，且藉由最佳化演算法得以保證微電網中的柴油機組發電成本最小化，使得傳統機組發電廠達到最經濟的運轉成本考量。與此同時微電網中的雙饋式感應風力發電機(Doubly-Fed Induction Generator, DFIG)的葉片旋角(Pitch angle)則維持 0°，確保風機葉片從風中擷取到最大風能，讓風電業者在不同風速下，都能以最大功率匯入微電網，避免風能溢出浪費的狀況產生。若是電池儲能預防控制無法改善電網頻率至安全的界線，則加入風機的葉片旋角(Pitch angle)之預防控制來協助改善微電網系統之頻率低點。 本論文藉由MATLAB®/Simulink軟體進行模擬，並以微電網之非線性數學模型為研究範例，來驗證本論文所提出之儲能系統自動發電控制策略及系統頻率低點之預防控制的有效性。

The purpose of this paper is to design the Automatic Generation Control(AGC) strategy of the Battery Energy Storage System(BESS) in the microgrid to control the output power of the BESS , so as to improve the frequency response due to output fluctuation of the wind turbine and the small-scale load disturbance. Another contribution of this paper is that when the microgrid encounters large-scale load disturbances, using the preventive control method proposed in this paper, taking advantage of the fast response speed of the BESS, combined with the Firefly Algorithm(FA) to design parameters of the BESS. Related parameters such as optimal output power and optimal charging/discharging timing. Under the premise of sufficient SOC, the method can prevent the occurrence of power failure in the microgrid, and the optimization algorithm can ensure the generation cost of diesel units in the microgrid is minimized. At the same time, the pitch angle of DFIG in the microgrid is maintained at 0° to ensure that the wind turbine blades capture the maximum wind energy from the wind, so that the wind power operator can offer the maximum power under different wind speeds into the microgrid, also avoid spilling of wind energy. In this paper, MATLAB®/Simulink software is used for simulation, and the nonlinear mathematical model of the microgrid is used as a study system to verify the effectiveness of the proposed methods in this paper, the AGC strategy of the BESS and the prevention control of the low frequency event.