- 學位論文
竹科69 kV第二環路保護系統之分析研究
Study of the 69 kV Second Loop Protection System of Hsinchu Science Park
摘要
高品質的電力是科學園區高科技產業所需，電力公司在科學園區投入大量的人力及物力，以環路方式供電，期能提高供電可靠度與品質。93年4月10日發生竹科大停電事故，造成重大損失，衍生出環路供電之保護問題。 本文以新竹科學園區69kV第二環路保護系統做個案研究與改善，在主保護方面，利用數位式差流電驛的優點，例如故障定位，可迅速找到故障點，縮短停電時間等，將原傳統副線電驛改用數位式差流電驛，且將環路後衛保護原使用方向性過電流電驛改用數位式測距電驛，並以ASPEN軟體模擬竹科69kV第二環路後衛保護加以比較。 模擬後衛保護協調結果發現，69kV環路的用戶愈多，後衛保護電驛若使用方向性過電流電驛，因協調間距CTI (Coordination Time Interval)所須協調的時間愈久，最長清除故障時間為2.12秒，最短清除故障時間為1.03秒，致使台電匯流排出口處之過電流電驛動作時間很長，若發生地下電纜故障，因故障電流流經電力設備之時間過長，將造成電力設備之壽命減短或毀損，對電力系統產生嚴重的影響。 若台電端及科學園區環路用戶的後衛保護均改用三區間數位式測距電驛，不但可以達到良好的保護協調並縮短清除故障時間，最長清除故障時間為0.33秒，最短清除故障時間為0.15秒，對科學園區高科技產業，可以提高供電品質及降低電壓驟降時間。
並列摘要
As high-quality electric power is critical for the smooth and effective operation of high-tech residents in science parks, power companies have invested huge amount of human and financial resources building loop systems to ehance both the quality and reliability of power supply. On April 10, 2004, however, the renowned Hsinchu Science Park experienced a large-sclae power outage, not only causing great financial losses but also raising grave concerns over the problem of protection for loop system. The thesis accordingly serves as a case study examining the protection system of the 69kV second loop circuit in Hsinchu Science Park and presenting suggestions for reinforced protection. For main protection, digital differential relays (due to their ability to locate faults and reduce the duration of power outage in an efficient manner) are adopted to replace traditional pilot relays. For backup protection, digital distance relays are used to substitute directional overcurrent protection relays, and ASPEN software is used to simulate both the existing and proposed settings for the 69kV second loop circuit in Hsinchu Science Park for comparison and verification of effectiveness. According to the results of simulating the coordination of backup protection, as the number of users in the 69kv loop circuit escalates, the directional overcurrent protection realys needs more time to complete the coordination as indicated by the longer CTI (Coordination Time Interval). The longest time of falult clearance reads 2.12 seconds, and the shortest is approximately 1.03 seconds. Prolonged coordination time in turn leads to the increase in the action time of the overcurrent relays at the exportations of bus. Failure to clear the fault in a short time may damage the power equipments and shorten their live as the fault current takes to long to flow through the power equipments. If the three-zone digital distance relays are used by Taiwan Power at Hsinchu Science Park, both the time of fault clearance can be reduced (the longest reads 0.33 seconds and the shortest 0.15 seconds) and better protection coordination can be achieved. With the effectiveness of its proposed solutions verified, the thesis builds its major contribution in its ability to improve the quality of power supply and shorten the time of voltage sag in high-tech science parks.