二次變電所並聯電容器切換暫態之研究

A Study of Shunt Capacitor Switching Transients in a Secondary Substation

鐘文成(Wen-Cheng Chung)

指導教授 ： 李清吟

國立臺北科技大學/機電學院/電機工程系所/碩士(2005年)

摘要

電力系統供應之功率是隨負載需求而變動，為了穩定系統電壓及改善功因，電力公司分別在尖、離峰負載時，投入、切離電容器以為因應。電容器操作時伴隨產生的異常過電壓、突入電流等暫態現象，並不單單侷限於電容器組或斷路器上，也影響著系統上之電力設備。
本文針對台電士林二次變電所內之四座主變壓器，藉由電磁暫態分析程式ATP/EMTP模擬，探討二次側匯流排之並聯電容器組在投入、切離之暫態現象。模擬條件分別以峰值電壓一次投入、零值電壓一次投入與零值電壓同步投入，依四座主變壓器二次側匯流排有無並聯電容器之狀況，檢討將各電容器組投入、切離，對系統供應之負載端電壓、負載端電流、變壓器一次側匯流排電壓、斷路器電流與其端電壓之暫態影響，並分析偶發事故或停電檢修時，當系統主變壓器為N-1時，系統需併聯供電之狀況下，電容器組投入，其操作暫態現象對系統之衝擊。
分析結果顯示，當主變壓器二次側匯流排有並聯電容器組時，任一電容器組投入，均會對其他主變壓器供應之系統，造成暫態影響。同時發現，若系統三座主變壓器二次側匯流排均已並聯上電容器組，當第四座主變壓器二次側匯流排再投入電容器組時，會造成系統最大之衝擊。系統主變壓器N-1需併聯供電並投入電容器組時，於其斷路器上之突入電流比未併聯供電時要大，對未加入併聯供電之變壓器系統影響較低。

關鍵字

穩定電壓 ； 改善功因 ； 並聯電容器組 ； 暫態 ； 過電壓 ； 突入電流 ； ATP/EMTP ； 偶發事故分析

並列摘要

In the power system, the output of power supply would be changed with the loading demand. This change is matched with the peak load or low load. For the system stability of the power supply and power factor improvement, the capacitor used is necessary. On the other hand, the capacitor operated in the power system would produce the side effect of Over-voltage and Inrush current within the system, not only for the capacitor itself or circuit breaker
.
This paper investigates main transformer in Taipower system Shi-Ling distribution substation and use ATP/EMTP simulation this distribution substation to analysis the transient phenomenon of shunt capacitor energization, de-energization in second bus. The methods of peak voltage added once, zero voltage added once and zero voltage added in synchronization are used as the simulation condition. It is depended on the combination of the four main transformers with the connection of shunt capacitor in accordance with its second bus, discuss the transient effect of various operations such as load terminal voltage supplied from the system, load terminal current, bus voltage, the circuit and voltage of circuit breaker. Furthermore, the contingency analysis is taken for the impact of the transient effect with the capacitor energization under the condition of N-1 (1 out of N), the remained loading from the stopped transformer would be supplied by other transformers.
The experimental result indicates that the second bus connects with shunt capacitor, capacitor energization of any main transformer, the system that will be supplied to each main transformer, causes the transient effect. Furthermore, the biggest impact of transient effect is under the condition changing from four main transformers with second bus connecting three shunt capacitors to four main transformers with second bus connecting fourth shunt capacitors. A novel result is found from the experiment that the transformer system in parallel power supplied with capacitor energization, the inrush current of N-1 system would be bigger then the four transformers with second bus connecting four shunt capacitors. Another important result is found that the influence to the two main transformers is less than the one, which has the extra loading of the stopping main transformer, with the capacitor energization

並列關鍵字

Shunt capacitor ； Power factor improvement ； Stable voltage ； Transient ； Over-voltages ； Inrush current ； ATP/EMTP ； Contingency analysis

參考文獻

Pre-Insertion Inductors for Mitigating Remote Overvoltages Due to Shunt

pp. 1226-1338, July 1993.

Customer Power Problems Due to Voltage Magnification,” IEEE Trans. on Power

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Unique Multipurpose Damping Circuit for Capacitor Bank Switching,” IEEE