高壓直流系統常見事故之研究

A Study of Common Accidents in HVDC Transmission System

陳勇錩(Yong-Chang Chen)

指導教授 ： 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(2009年)

摘要

高電壓、大功率半導體元件不斷地更新和發展，功率變換控制技術的日臻完善，大舉地推動了電力電子技術在電力工業中的應用。從電能的產生、傳輸、儲存一直到變換和控制的各個環節已經有許多獨特的應用實例，高壓直流輸電就是其中之一。電力電子技術廣泛應用於電力工業，對增強電力系統運行的穩定性和安全性，提高輸電能力和用電效率，在節能及改善電能質量等方面將發揮越來越重要的作用。在未來的新世紀，將會有更多更新的高電壓大功率半導體元件和裝置投入電力工業的實際運轉中，使目前基本不可控的系統變為靈活可控，對未來電力系統的發展將產生重大的影響。本論文主要研究高壓直流輸電系統事故所引起的換相失敗對電力系統之影響。換相失敗為在每一個單橋中，當處於同一半橋中的兩個橋臂之間的換相結束後，剛退出運行的閥在反向電壓作用的一段時間內，如果未能恢復正向阻斷能力，或者在反向電壓期間換相過程一直未能完整地進行完成，在閥電壓轉變為正向時，該閥將會不經觸發而再次導通，與剛觸發導通的閥發生反換相，這個過程就是換相失敗。經由模擬結果顯示，當事故發生交流側單相短路經電阻接地和三相短路經電阻接地並不會發生換相失敗，而單相短路直接接地、相間短路、三相短路直接接地或直流側換流器內部閥體故障，則將會使換相失敗發生， 換相失敗將使得直流系統在一段時間內直流電流增大，直流電壓下降，直流輸送功率降低甚至中斷。因此分析各種故障下的電壓、電流、觸發角、熄滅角之暫態響應及調變能力，確認系統是否安全，以避免造成更嚴重之情況具有重要的意義。

關鍵字

高壓直流系統 ； 電力系統故障 ； 閥體故障 ； 換相失敗

並列摘要

High voltage, high-power semiconductor components constantly renew and develop, the power varied control technology becomes better and better, having promoted the application of power electronics technology in power industry on a large scale. It has a lot of unique applications from the power's production, transmission, storage to each link of transform and control, high voltage direct current(HVDC) transmission system is in one of them. Power electronics technology has been wildly applied in power industry, for strengthening the stability and security that the power system operates, improving transmitting capacity and power consuming efficiency, it will play a more and more important role in energy-conservation and improve energy quality. The new era in the future, there will be more and newer high voltage, high-power semiconductor components and apparatuses plunged into the practical operation of power industry, it makes the original uncontrollable system become flexible, it will have a significantly influence for power system in the future. The main study of commutation failures caused by accidents in HVDC system are represented in this paper for analyzing the impact on power system. Commutation failures mean that in each single bridge, after commutation between two bridges which are in the same half bridge, valve which is out of motion is in reverse voltage effect for a period of time, if it can’t recovery the ability of obverse leaving off, or it can’t be completely finished during the commutation process in reverse voltage, when the valve voltage becomes into obverse, the valve will be conducted again without firing, occurs reverse commutation with the valve which is just conducted by pulse, this process is commutation failure. By the result of simulation, it won’t occur commutation failures when faults happen single phase short circuit grounded with resistance and three phases short circuit grounded with resistance, but it will make commutation failures happen when single phase short circuit grounded directly, phase to phase short circuit, three phases short circuit grounded directly or internal faults on the thyristor valve on the dc side, commutation failures make HVDC’s dc current increase, dc voltage decrease, dc power delivery decrease or even blocked during a specific time. So it has a profound significance to analyze the transient responses and regulation ability of the voltage, current, firing angle, extinction angle during all kinds of faults to make sure the system’s safety for preventing more serious circumstances.

並列關鍵字

HVDC Transmission system ； Power System Faults ； Valve Faults ； Commutation Failures

參考文獻

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