GÜÇ SİSTEMLERİ GEÇİCİ REJİM SİMÜLASYONLARINDA ZAMAN ADIM UZUNLUĞU ETKİSİNİN İNCELENMESİ

Abstract

Güç sistemlerinde yıldırım düşmesi gibi yüksek frekanslı geçici rejim olaylarının simülasyonu, ekipman güvenliği ve koruma sistemi tasarımı için hayati önem taşımaktadır. Bu çalışmada, geçici rejim analizlerinin doğruluğunu belirleyen en kritik parametrelerden biri olan zaman adım uzunluğunun (Δt) sonuçlar üzerindeki etkisi kapsamlı bir şekilde analiz edilmiştir. Çalışma kapsamında, 300 km uzunluğunda dağınık parametreli bir iletim hattı, Heidler modeli ile temsil edilen bir yıldırım darbesi ve 10 diskten oluşan merdiven ağı tipi bir güç transformatörü modeli kullanılarak karmaşık bir test sistemi oluşturulmuştur. Analiz sürecinde, analitik bir yaklaşım olan durum-uzayı yöntemi ile endüstriyel standart ATP-EMTP yazılımı üzerinden alınan sonuçlar karşılaştırılmıştır. Simülasyonlar, 5x10−8 s ile 5x10−4 s arasında değişen farklı zaman adımları için tekrarlanmıştır. Elde edilen bulgular, zaman adım uzunluğu arttıkça akım ve gerilim dalga formlarının karakteristik yapısının bozulduğunu ve tepe değerlerinde büyük sapmalar meydana geldiğini göstermiştir. Özellikle büyük zaman adımlarında, kA mertebesindeki akım değerlerinin 1 A'in altına düştüğü ve sonuçların fiziksel gerçekliğini tamamen yitirerek sayısal kararsızlığa yol açtığı tespit edilmiştir. Çalışma, yüksek frekanslı bileşenleri içeren geçici olayların doğru modellenmesi için zaman adımının sadece Nyquist-Shannon kriterini sağlamakla kalmayıp, sistemin dinamik yanıtlarını yakalayacak kadar hassas seçilmesinin mühendislik hesaplamaları açısından zorunlu olduğunu kanıtlamaktadır.

Keywords

• Geçici rejim analizi
• Zaman adım uzunluğu
• Durum-uzayı yöntemi
• ATP-EMTP
• Dağınık parametreli hatlar.

AN ANALYSIS OF THE EFFECT OF TIME STEP LENGTH IN TRANSIENT SIMULATIONS OF POWER SYSTEMS

Abstract

Bearing Simulation of high-frequency transient events, such as lightning strikes in power systems, is vital for equipment safety and protection system design . In this study, the impact of time step length (Δt), which is one of the most critical parameters determining the accuracy of transient analysis, has been comprehensively analyzed . Within the scope of the study, a complex test system was created using a 300 km distributed parameter transmission line, a lightning stroke represented by the Heidler model, and a ladder network type power transformer model consisting of 10 disks. In the analysis process, results obtained from the analytical state-space method and the industry-standard ATP-EMTP software were compared. Simulations were conducted for different time steps ranging from 5x10⁻⁸ s to 5x10⁻⁴ s. The findings demonstrated that as the time step length increases, the characteristic structure of current and voltage waveforms deteriorates, and significant deviations occur in peak values. Especially at large time steps, current values in the kA range dropped below 1 A, losing physical reality and leading to numerical instability. The study proves that for the accurate modeling of transient events containing high-frequency components, choosing a time step that is precise enough to capture the system's dynamic responses rather than merely satisfying the Nyquist-Shannon criterion is essential for reliable engineering calculations

Keywords

• Transient analysis
• Time step length
• State-space method
• ATP-EMTP
• Distributed parameter lines.

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