利用閘切串聯電阻改善弱系統鼠籠式感應風力發電機之低電壓穿越能力

Thyristor Switched Series Resistor for Low Voltage Ride Through of Weak Tie Connected Wind Farms with SCIGs

楊子毅(Tzu-Yi Yang)

指導教授 ： 許源浴

國立臺灣大學/電機資訊學院/電機工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.00141

摘要

風力發電機之出力受發電機端電壓影響甚鉅，對於轉子側短路的鼠籠式風力發電機(Squirrel-Cage Induction Generators, SCIG)更是如此，因此其低電壓穿越能力(Low Voltage Ride Through, LVRT)成為了設計風力發電廠時重要的指標項目之一。
本文利用閘切串聯電阻(Thyristor Switched Series Resistor, TSSR)在電網發生故障時提升風力發電廠的端電壓，以其串聯電阻吸收過剩的實功進而提高風力發電廠的低電壓穿越能力。此外，針對串聯電阻值的設計，同時考慮了暫態穩定度與小訊號穩定度的需求，選擇出適當大小的串聯電阻值，將閘切串聯電阻對系統的衝擊降到最低。
本文以MATLABR/SIMULINK/SimPowerSystems進行分析模擬與驗證。理論分析與模擬結果顯示，閘切串聯電阻能夠大幅提高鼠籠式風力發電機的低電壓穿越能力，且其有控制簡單與價格經濟的優點，對於改善系統較弱的偏遠地區之風力發電機是相當可行的補償方式，也可直接應用於其他現有之風力發電廠。

關鍵字

風力發電 ； 鼠籠式感應發電機 ； 低電壓穿越 ； 閘切串聯電阻 ； 暫態穩定度 ； 小訊號穩定度

並列摘要

Series resistors can be used to improve generator voltage dip due to a fault in the grid and enhance generator fault ride-through (FRT) or low voltage ride-through (LVRT) capability. To determine proper values for the inserted series resistance, transient stability analysis and small signal stability analysis are performed on squirrel-cage induction generators connected to the grid through a weak tie. Stable regions for transient stability and small signal stability were plotted. It is concluded from the results from stability analyses that different values of series resistors should be used for different fault voltages in order to ensure wind farm stability. To achieve the goal of variable series resistances under different fault voltages, a thyristor switched series resistor (TSSR) which comprises four thyristor switched resistors connected in series is proposed in this paper. Control laws for the TSSR are derived. Simulation results indicate that generator terminal voltage and electromagnetic torque are raised under various fault events and the LVRT capability is improved by using the proposed TSSR.

並列關鍵字

Wind power generation ； squirrel-cage induction generator ； low voltage ride-through ； thyristor switched series resistor ； transient stability ； small signal stability

參考文獻

[16]林士鈞, “雙饋式感應風力發電機之小訊號穩定度分析,”臺灣大學電機所碩士論文, 2012.

[19]張家閔, “動態電壓調整器應用在穩定併聯於市電之感應發電機端電壓之研究,”臺灣大學電機所碩士論文, 2012.

[5]S.S. Murthy, O.P. Malik, and A.K. Tandon, “Analysis of self-excited induction generators,” IEE Proc., Vol. 129, Pt. C, No. 6, pp. 260-265, November 1982.

[6]T. J. E. Miller, Reactive Power Control in Electric Systems, John Wiley & Sons, Inc, 1982.

[7]N. G. Hingorani and L. Gyugyi, Understanding FACTS：Concepts and Technology of Flexible AC Transmission Systems, IEEE Press, 2000.