Voltage stability monitoring using a modified thevenin impedance

Abstract

-This paper presents a method for voltage stability monitoring based on the maximum power transfer to the load. The only required information is the system topology, the data from PMUs and the operational status of synchronous generators. With this information, the Thevenin impedance seen from a load bus can be estimated and by using the Thevenin theorem for maximum power transfer an impedance based stability index can be established. Since the Thevenin impedance is influenced by the operational conditions of the synchronous generators, it is consequently not a constant value and differs from the short circuit impedance of the bus. It is emphasized that the method requires only the information of the considered subsystem. Therefore, since the computation requirement is insignificant, the algorithm can be used for online monitoring. The validation of the approach is achieved by simulating a simple transmission system.

Güç Sistemlerinde Thevenin Eşdeğer Devresi Kullanılarak Gerilim Kararlılığı Sınırlarının Gerçek Zamanlı Değerlendirmesi

“…Güç sisteminde ilgili bara arkasında kalan güç sisteminin Thevenin eşdeğeri bilindiği takdirde baradan çekebilecek maksimum güç, maksimum güç transferi yasası ile hesaplanabilir. Yük empedansının (ZYük), Thevenin empedansına (ZTh) eşit olduğu durumda yüke transfer edilebilecek görünür güç maksimum olur [21]. Şekil 3'deki yüke transfer edilecek gücün empedansa göre değişimi grafik olarak verilmiştir.…”

Voltage stability assessment accounting for non‐linearity of Thévenin voltages

“…In [12] the activation of overexcitation limiters (OXLs) is anticipated to more accurately determine the maximum deliverable power to the load. In [13] one of four possible operating states of a generator is modelled as an impedance and included in the network to determine the MPT to the load. The four states are; no limits have been reached, the OXL or the armature current limiter are activated or in case the generator injects maximum active power.…”

Avaliação de Índices de Estabilidade de Tensão para Utilização em Sistemas de Medições Fasoriais

“…Três diferentes metodologias são comumente utilizadas para monitor a margem de estabilidade de tensão com PMUs: métodos baseadas no teorema de Thévenin, aquelas baseadas em Redes Neurais Artificiais eíndices de estabilidade de tensão. Gong et al (2006), Corsi and Taranto (2008), Mou et al (2012), Su and Liu (2016) e Polster et al (2017) utilizaram o equivalente de Thévenin, calculado a partir de medidas de PMU, para avaliar a estabilidade de tensão em tempo real.…”