基於廣域量測系統之電力系統電壓穩定度監測與控制之研究

Abstract

本論文主要研究以廣域量測系統為基礎之電力系統電壓穩定度監測與控 制。首先本文提出了一個有效的方法用於計算電力系統之電壓穩定度裕度, 該方法結合了戴維寧等效電路以及三次樣條函數 (Cubic Splines) 外插技術來 加速連續負載潮流 (Continuation Power Flow, CPFLOW) 演算法的計算,使其 能夠快速地求得系統之電壓崩潰點。有了這個新的方法,系統操作人員就可 以準確且快速地得知系統電壓穩定度的狀況。為了讓電力系統有更好的電壓 調整,本文提出了一個新的適應性控制方法於電力系統之二次電壓控制 (Secondary Voltage Control, SVC),此方法能夠讓整個系統的電壓大小都維持 在可接受的範圍,而且此適應性控制方法的輸入訊號是藉由線上估測負載虛 功擾動而得。此外由於此方法的計算量很少,故適合於線上的應用。為了使 系統能操作於安全的區域,本文發展了一套以同步相量為基礎之廣域電壓穩 定度監測與控制系統,該方法同時利用了所觀測匯流排上的同步電壓大小以 及電壓穩定度裕度指標作為觸發訊號,並且以最佳化的方式控制電力系統中 的虛功源來達到可靠且有效的電壓大小以及電壓穩定度調整。針對上述的各 種方法,本文亦做了大量的模擬來驗證其有效性。

The aim of this dissertation is to study the power system voltage stability monitoring and control based on wide area measurement system. First, we propose an efficient method for the computation of static voltage stability margin in a power system. The proposed method combines Thevenin equivalent network approach with cubic spline extrapolation technique to accelerate the continuation power flow (CPFLOW) algorithm to quickly determine the voltage collapse point. With this new method, power system operators are able to accurately and rapidly recognize how far the system is away from a possible instability event. In order to achieve better voltage regulation in power systems, a new adaptive control approach to power system secondary voltage control (SVC) problem is presented. The proposed method is able to maintain system voltage profile at acceptable level across the entire power grid. The proposed method is adaptive in the sense that load reactive power disturbance is estimated on-line for computing the adaptive control inputs. Moreover, the computational burden of the proposed method is low to make it suitable for on-line applications. For secure grid operations, a synchrophasor based wide area voltage stability monitoring and control scheme is developed. The proposed scheme utilizes both synchronized voltage magnitudes of monitored buses and the index of voltage stability margin as trigger signals to optimally control reactive power sources to achieve reliable and efficient voltage profile/stability regulation in power systems. All the methods mentioned above are evaluated with extensive simulation studies. The test results are promising and confirming the effectiveness of the proposed methods.