Abstract
Fault detection in resonant grounding (RG) distribution networks remains a challenge due to weak fault signals, extremely complex fault conditions, and unstable intermittent arc grounding faults. This paper addresses this issue by applying generalized S-transform (GST) with a variable factor to conduct denoising of transient zero-sequence currents based on threshold filtering followed by time-frequency distribution filtering in sequence. Meanwhile, this paper proposes a comprehensive multi-criteria faulty feeder detection method based on the transient zero-sequence current polarity (criterion 1), the energy relative entropy (criterion 2), and the total transient current energy (criterion 3). Here, criteria 2 and 3 are based on the time-frequency representation of the GST. The performances of the proposed denoising and faulty feeder detection methods are evaluated under single line to ground faults based on simulations conducted using a modeled 10 kV RG networks with overhead and cable mixed lines in addition to reasonably sophisticated permanent and intermittent arc discharge models to ensure that the simulations faithfully represent actual complex working conditions. Compared with existing method, simulation experiments and field test show that the method proposed in this paper provide a better denoising effect with stronger self-adaptability, higher detection accuracy, and a faster calculation speed.
Highlights
Most of the distribution networks in China operating in the range of 10–35 kV are grounded by arc suppression coils
80% of faults that occur in resonant grounding (RG) networks are single line to ground (SLG) faults
3) THE REALITY OF SIMULATION SYSTEM The performances of the proposed denoising and faulty feeder detection methods are evaluated under both constant resistance faults and arc grounding faults based on simulations conducted using a modeled 10 kV RG distribution network with an overhead and cable mixed line structure in addition to a reasonably sophisticated arc discharge model to ensure that the simulations faithfully represent actual complex working conditions
Summary
Most of the distribution networks in China operating in the range of 10–35 kV are grounded by arc suppression coils. Most existing methods detect faulty feeder by recorded fault data without denoising, but this proposed method applies threshold filtering and time-frequency distribution filtering based on the generalized S-transform with a variable factor, which can detect correct faulty feeder in most noisy environments. The second and third criteria are based on the time-frequency representation of the GSTσ approach The method considers both the direction and energy of transient signal currents, which provides more comprehensive and accurate detection results than single-criterion methods. 3) THE REALITY OF SIMULATION SYSTEM The performances of the proposed denoising and faulty feeder detection methods are evaluated under both constant resistance faults and arc grounding faults based on simulations conducted using a modeled 10 kV RG distribution network with an overhead and cable mixed line structure in addition to a reasonably sophisticated arc discharge model to ensure that the simulations faithfully represent actual complex working conditions.
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