Time Delay Margins Computation for Stability of Hybrid Power Systems

Öz

In load frequency control (LFC), it is essential to transmit measurements of control signals from the control center to plant side and remote terminal units (RTU) to control center. Therefore, time delays become inevitable due to the use of conventional communication channels. The dynamic performance of LFC system would be degraded by these delays.   This paper is dedicated to the delay-dependent stability of the LFC of hybrid power generation subsystem. The system studied includes wind turbine generator (WTG), photovoltaic system (PV), ultra-capacitor (UC) bank for energy storage, fuel cell (FC) system and diesel generator(DG). Delay margin is stated for the upper bound on the delay for stability of LFC system. An analytical method is used to compute delay margins. Delay margins are calculated for wide range of proportional-integral (PI) controller. Such results could be utilized to tune the PI controllers as to achieve a compromise between the dynamic performance and the delay margin. It has been determined in which intervals, the controller parameters of the proposed hybrid system can be selected while the system is in stable region. the results are presented in tables and graphs. Simulation study of the proposed system with Matlab / Simulink was performed. The results of the simulation studies and the theoretical studies showed compatibility. Simulation studies verify the effectiveness of the proposed method.

Anahtar Kelimeler

• Delay-dependent stability,delay margin,electrical power systems stability,load frequency control

Melez Güç Sistemlerinde Zaman Gecikmesinin Kararlılık Analizi

Öz

Yük frekans kontrolü (LFC) de, kontrol sinyallerinin ölçümlerini kontrol merkezinden kontrol ünitesine ve uzak terminal ünitelerinden (RTU) kontrol merkezine iletmek esastır. Bu nedenle, geleneksel iletişim kanallarının kullanılması nedeniyle zaman gecikmeleri kaçınılmaz hale geliyor. LFC sisteminin dinamik performansı bu gecikmelerle azalır. Bu makale, yerel melez enerji üretim  sisteminin LFC'sinin gecikmeye bağlı kararlılığını analiz etmektedir. Çalışılan sistem, rüzgar türbini jeneratörü (WTG), fotovoltaik sistem (PV), enerji depolama için ultra-kapasitör (UC) bankası, yakıt hücresi (FC) sistemi ve dizel jeneratör (DG) içerir. Bu çalışmada, böyle bir sistemin modellemesi ve benzetimi yapılmıştır. Gecikme marjı, LFC sisteminin kararlılık gecikmesinde üst sınırı belirtmektedir. Gecikme marjlarını hesaplamak için analitik bir yöntem kullanılmıştır. Gecikme marjları, oransal- integral (PI) kontrolörün geniş bir aralığı için hesaplanmıştır. Bu sonuçlar, PI kontrolör parametrelerini, sistemin dinamik performansı ile gecikme marjı arasında dengeli bir seçim yapacak şekilde ayarlamak için kullanılabilir. Önerilen hibrit sistemin kontrolör parametrelerinin kararlılık çerçevesinde hangi aralıklarda seçile bilineceği tespit edilerek, tablo ve grafik halinde sunulmuştur. Önerilen sistemin Matlab/Simulink ile bezetim çalışması gerçekleştirilmiştir.  Simülasyon çalışmaları ile teorik çalışmaların sonuçları uyumluluk göstermiştir. Simülasyon çalışmaları önerilen yöntemin etkinliğini doğrulamaktadır.

Anahtar Kelimeler

• Gecikmeye bağlı stabilite,gecikme marjı,elektriksel güç sistem kararlılığı,yük frekans kontrolü

Kaynakça

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