電流注入法應用於主動式孤島偵測對電力品質之影響

Abstract

由於電力需求的增加以及減少傳統石化燃料對環境的衝擊，分散式電源系統(Distributed Resources, DR)已被廣泛使用。很多DR系統都使用再生能源如風力、太陽光電池或燃料電池，當DR系統與市電網路併聯運轉時，電力品質問題就顯得相當重要。電力品質問題包括頻率漂移、電壓擾動、諧波等問題，除此之外孤島運轉也是一個重要的課題。孤島乃是指當市電由於意外事故或損壞而中斷時，DR仍持續運轉的現象。 基於維修人員及電力設備的安全，應該避免孤島運轉，孤島運轉偵測的方法可分為兩類：主動式偵測法及被動式偵測法，電流注入法是一種主動偵測法，該方法經由電壓源型換流器的直交軸電流控制器注入一干擾訊號，在孤島發生後，此干擾訊號將導致共同耦合點(Point of Common Coupling, PCC)的電壓擾動或頻率漂移，然而注入干擾訊於系統中可能導致電力品質的損失。 本論文以電腦模擬軟體MATLAB/Simulink實現一個模擬平台，利用此平台分析注入干擾訊號對電力品質造成的影響，尋找出合適的注入干擾範圍。

Distributed resources(DR) systems have been broadly used as a result of the increased demand for electricity and the requirement to reduce the impact on the environment from tradition fossil fuel of power production. Many of the DR systems make use of renewable energy such as wind power, photovoltaic cell, or fuel cell. When the DR systems are operated in parallel with utility power systems, the power quality problems are significant. Power quality problems include frequency deviation, voltage fluctuation, harmonics, etc. In addition, islanding operation is one important topics. Islanding is the continued operation of the DR when the grid has been removed on purpose, by accident, or by damage. The islanding operation should be avoided because of safety reasons for maintenance man and electrical facilities. Islanding detection methods may be divided into two categories: passive methods and active methods. The current injection method is one of the active methods. The method is based on injecting a disturbance signal into the system through either the direct axis or the quadrature axis current controllers of the voltage-sourced converter. The disturbance signal causes voltage fluctuation or frequency deviation at the point of common coupling(PCC) under islanded conditions. However, injecting a disturbance into the system may result in the loss of power quality. A simulation platform by software MATLAB/Simulink has been implemented in this thesis, which is used to analyze the effect on the power quality in order to find the appropriate range of the injected disturbance signal.