大潭發電廠保護協調分析

摘　要本研究的主題是針對大潭發電廠進行分析，大潭發電廠為新建電廠，全廠總發電量佔北部用電約三成，一旦發生事故，對系統影響甚巨，若因保護協調不當而致全廠停電，亦可能會造成系統全黑，因此有必要對大潭發電廠進行保護協調分析。本研究對大潭發電廠分析的主要內容包括：建立保護協調分析模型、蒐集所需參數，再依不同的機組運轉模式，計算故障電流並檢討電驛設定等。機組與機組間的相互影響是否存在電驛協調問題須要進一步探討，此外，保護協調分析需要考慮每一迴路可能的最大與最小故障電流，包括相故障與接地故障電流。所稱最大、最小故障電流係指系統最多、最少電源同時併用時的故障電流。據之，本研究是以大潭電廠全部（共12部）345kV發電機組運轉並假設該電廠的開關場三相短路容量為98年度台電系統的最大短路容量；至於最小短路電流則模擬全部機組停用，而由外部系統供電至廠內，且開關場的短路容量為98年度系統的最小短路容量。針對電廠電力系統所模擬的故障點涵蓋發電機的輸出端、主變壓器與開關場之間的地下電纜、輔助變壓器高、低壓側以及4.16kV匯流排（但不含發電機本身及480V系統）。據之，對每個故障點計算最大、最小的相故障電流以及接地故障電流進行保護協調檢討並提出改善建議，包括目前的電驛設定以及故障電流計算程序。關鍵字：發電廠電力系統、故障電流計算、保護協調

關鍵字

保護協調；故障電流計算；發電廠電力系統

並列摘要

Abstract This research aims at the protection coordination analysis of Datan Power Plant. Datan is a newly built power plant; the total power output is approximately 30% of the demand of northern Taiwan. Thus, an in-plant outage could affect the power system of Taiwan, and, if the protection system is not well coordinated, the whole plant could even outage and result in blackout of Taipower system. It is hence necessitated to evaluate the protection coordination of the Datan power system. The main content of this research includes the model building and the parameter collection for the protection analysis, the fault current calculation and the protection coordination analysis, under all possible operating modes of Datan’s generators. In the protection analysis, the maximum and the minimum fault current for both the phase and the phase-to–ground faults should be evaluated. The maximum fault current refers to the Datan’s operating mode having all (total 12) generating units under operation and the plant’s 345kV switchyard of operating at the maximum short-circuit capacity of Taipower system in year 2009; as to the minimum fault current, it is assumed Datan’s all generators are out of service and the switchyard is operating at the minimum short-circuit capacity of Taipower in 2009. The fault locations evaluated in this study include the output terminal of each generating unit, the 345kV underground cable connecting the main transformer and the switchyard, both sides of the auxiliary transformer, and the 4.16kV bus, （not including generator itself and the 480V system）, so that for each fault location, the maximum and the minimum fault current of both the phase fault and the ground fault are evaluated. Based on the protection coordination analysis results, suggestions are made ranging from the revised relay setting to the fault current calculation procedure. Keywords: power system, fault current calculation, protection coordination