基於同步相量量測單元之輸電網路故障定位演算法之研究

A Study on PMU Based Fault Location Algorithms for Transmission Networks

連凱平(Kai-Ping Lien)

指導教授 ： 劉志文

國立臺灣大學/電機資訊學院/電機工程學研究所/博士(2005年)

https://doi.org/10.6342/NTU.2005.00928

摘要

本論文提出以同步相量量測和數位濾波技術為基礎，適用於電力輸電網路和多端輸電線路之新型故障定位演算法。隨著電力輸電網路日益龐大和複雜，傳統的故障定位法已無法勝任此一趨勢的變化。輸電網路需要即時的量測和監測，而故障定位的準確度，更取決於同步量測的準確，而以GPS (Global Positioning System, GPS)當作參考時間基準的PMU (Phasor Measurement Unit, PMU)量測技術，提供同步量測最好的選擇。所以本文故障定位的架構是以該技術所發展出來的。
首先，我們利用既有的電力系統狀態觀測的同步相量量測單元系統，提出一種針對全域電力輸電網路，新的故障定位可觀測性演算法，當輸電網路發生故障時，藉由本文提出的故障定位可觀測性演算法，能即時判斷出故障的區間和位置。事實上，有關同步量測的實際應用是越來越多，例如，電力品質的監控、系統狀態的決定和故障定位等。一般來說，輸電電網所安裝的同步量測單元的個數，遠少於電網上匯流排的個數，在一般正常的狀態下，電力工程師可由這些有限個數的同步量測單元的訊號，得知電力系統狀態的良窳。但是當故障發生時，卻無法由這些有限的量測，得知故障發生在那一線段和位置。除非，我們願意提高安裝成本，將所有的匯流排都安裝同步量測單元，但那將是非常不經濟的作法。所以在考量安裝成本的前提下，本文先提出一種PMU個數最少的配置策略，進而發展出適用該配置策略的故障定位可觀測性演算法，其能兼顧成本和故障定位的準確性。在本論文中，我們藉由邏輯閘電路完成該演算法的故障線路選擇器，藉由該故障線路選擇器可精準的判別出故障線路和故障位置。藉由EMTP程式模擬一345kV輸電網路，驗証本文提出的故障定位可觀測性演算法。模擬結果顯示準確性可高達99.5%。
另外，因為電力輸電線路路權難以取得的緣故，因此存在很多的多端分枝輸電線路。該種複雜線路的故障定位，已非一般傳統的故障定位所能應付。針對此種線路，除了發展適用於多端輸電線路的故障定位演算法外，更需要精準的同步量測技術。所以本文提出一種以PMU同步量測技術為基礎，適用於多端輸電線路的故障定位演算法，它不須要複雜的運算而且經由簡單的判別準則，就可精確的判別出多端輸電線路上故障的分枝和故障位置，且該準則也可以判斷出外部故障。該準則適用於任何不同線路架構、不同電源和負載的多端輸電線路。而且不須要做任何的假設。經由大量的模擬，驗証本文提出的故障定位演算法，其故障區段選擇的準確度高達100%。而故障位置定位誤差遠小於1%。

關鍵字

故障定位 ； 同步相量量測單元

並列摘要

This dissertation presents multi-terminal fault location algorithms for power transmission networks and multi-terminal transmission lines based on Synchronized Phasor Measurement Unit (PMU). In the past, it was difficult to precisely synchronize the sampling at the ends of transmission lines due to the lack of a common timing reference. It is widely recognized that the multi-terminal fault location algorithms are subject to errors resulting from unsynchronized sampling clock. Use of a timing signal from Global Positioning System (GPS) can greatly reduce or eliminate the synchronization errors from the measurements.
First, we propose a new concept of fault location observability for transmission networks based on PMUs. The aim of this work is to improve fault locating accuracy of transmission networks using limited PMUs. Generally, the number of installed PMUs is typically much lower than the number of substations in a transmission network. Under normal conditions, power engineers may be able to determine power system state from the synchronized data of a few PMUs installed at cardinal power system nodes. When a fault occurs, it is very hard to accurately locate the fault position using the data provided from limited PMUs, unless we install PMUs at all substations of transmission network. However, it would be very uneconomic to install PMUs at all substations. Thus, we present a new fault location algorithm to meet those needs (accuracy and economy). In the beginning, we propose a minimal PMU placement strategy for fault location observability and then develop a novel fault location algorithm using minimal PMUs to classify fault section and calculate fault location for transmission networks. An EMTP/ATP simulation of a 345 kV system is conducted to evaluate the performance of the proposed algorithm. The tested cases include various fault types, fault locations, fault resistance, fault inception angles, etc. The study also considers the effect of various buses. Simulation results indicate that the accuracy of the proposed algorithm is better than 99.363%.
Second, we also present a new PMU-based fault location algorithm for multi-terminal transmission lines. The development of the algorithm is based on distributed transmission line model and synchronized positive sequence voltage and current phasors. The method is an analytical solution and its computational cost is very low since it does not require iterative operations. The EMTP/ATP simulation was conducted to verify the accuracy of the method. The simulation studies show that the algorithm provides a high degree of accuracy in fault location under various fault conditions such as fault types, fault positions, fault path resistance, pre-fault load flows, and line shunt capacitance, etc. The average fault location error under various fault conditions is well below 1%.

並列關鍵字

fault location ； PMU

參考文獻

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