Impact of Zero-Sequence Impedance errors on ground fault detection and line parameter estimation using phasor measurements

However, their performance is highly dependent on correct configuration of parameters such as positive-sequence and zero-sequence impedances and the resulting ground compensation factor (KE-factor).

While positive-sequence impedance remains consistent, zero-sequence impedance varies significantly with soil conditions, tower grounding, conductor configuration, and environmental factors. Conventional modelling often assumes uniform ground characteristics and simplified tower behaviour, leading to inaccurate impedance values and reducing the reliability of relay operation.

Therefore, transmission line model that incorporates realistic features such as finite ground wire lengths, tower grounding resistances, and mutual coupling effects is required. This paper investigates the sensitivity of zero-sequence impedance and the KE-factor to various influencing variables through simulations and case studies. A comparative analysis of zero sequence impedances in real overhead lines highlights the limitations of conventional models and the need for more accurate parameter estimation.

By addressing the impact of modelling assumptions and environmental variability, this study aims to enhance the reliability of distance protection in power transmission. The findings contribute to the development of more robust relay settings and improved fault detection capabilities, supporting the advancement of intelligent and adaptive protection schemes in modern power systems. The present study emphasizes the impact of zero sequence impedance on ground fault detection and importance of synchronized phasors in offering the possibility of allowing accurate estimation of transmission line parameters to improve accuracy in relay settings & post-event fault location, lead to a quicker restoration of the systems.