防止台電系統頻率驟降之新策略

A Novel Strategy to Prevent Frequency Decline for Taipower System

徐國彰(Kou-Chang Shyu)

指導教授 ： 李清吟 ； 陳昭榮

國立臺北科技大學/電資學院/電機工程系研究所/碩士(2007年)

摘要

台電系統為一南北狹長型獨立結構，且無互聯系統可作為奧援以強化系統穩定度，因此當系統遭受重大的擾動或某些發電機跳機時，容易造成系統頻率驟降，有可能引發串級骨牌效應進而導致系統瓦解，因此必須運用快速的備轉容量和適當的卸載策略以遏止頻率過度下降，並避免系統崩潰造成全停電。
本論文提出以單機-無限匯流排模型等效多機系統，藉由搖擺方程式求得頻率變動量及其下降率，並探討系統頻率變化係數對頻率驟降的影響，同時考量台電系統內具有自動發電控制和緊急發電控制功能的備轉容量，並設計低頻電驛卸載與頻率變動率卸載等兩種方法，以偵測頻率變動量及其下降速率作為判斷系統過載量大小的重要指標，再依據系統擾動的嚴重程度分別運用低頻電驛或結合頻率變動率電驛卸載，使系統頻率儘速回復至安全範圍。
使用本文所提方法，藉由EXCEL軟體進行數值分析，模擬台電2006年系統尖峰及離峰負載時，探討不同程度機組跳機(N-1∼N-10)及系統解聯等事故對系統頻率之影響，模擬後結果顯示，與台電現行卸載策略相較，運用本文所提的策略，除了可使系統頻率迅速回復至安全範圍外，並可減少用戶停電的範圍，提高系統的可靠性和穩定度。

關鍵字

低頻電驛卸載 ； 頻率下降率 ； 自動發電控制 ； 緊急發電控制 ； 備轉容量 ； 搖擺方程式

並列摘要

Taipower system is a longitudinal structure and isolated system without any adjacent interconnected power system. When the system experiences a huge disturbance or certain generators are tripped, it is likely to cause the system frequency to decline rapidly. This may result in cascading events and lead to the collapse of the power system. Therefore, both the rapid spinning reserve and adequate load shedding strategy can help to prevent the frequency decline and avoid the system blackout.
A method based on the simplified dynamic model that treat all the generators in the power system as one equivalent generator is proposed in this paper. The swing equation will be used to obtain frequency variation and the rate of frequency decline and to calculate the spinning reserve resulted from AGC and EGC functions. And two methods of load shedding are design that the under-frequency relays and the rate of change of frequency decline. According to the degree of severity of the disturbance, we then may make use of under-frequency relays or combine the rate of change of frequency decline relays to shed the load to restore the system frequency back to a safe range.
With the method of numerical analysis by using MS EXCEL software, this thesis proceeds to simulate Taipower System using data of peak and off-peak of year 2006 and study the impacts on generation losses and system separation. According to the simulation results, that selecting the methods we proposed in this thesis could restore system frequency to a safe range, decrease the amount of customer load required to shed, and enhance system reliability and stability.

並列關鍵字

underfrequency relay load shedding ； rate of frequency decline ； automatic generation control(AGC) ； emergency generation control(EGC) ； spinning reserve ； swing equation

參考文獻

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