Abstract
As renewable energy (RE) penetration has a continuously increasing trend, the protection of RE integrated power systems is a critical issue. Recently, power networks developed for grid integration of solar energy (SE) have been designed with the help of multi-tapped lines to integrate small- and medium-sized SE plants and simultaneously supplying power to the loads. These tapped lines create protection challenges. This paper introduces an algorithm for the recognition of faults in the grid to which a solar photovoltaic (PV) system is integrated. A fault index (FI) was introduced to identify faults. This FI was calculated by multiplying the Wigner distribution (WD) index and Alienation (ALN) index. The WD-index was based on the energy density of the current signal evaluated using Wigner distribution function. The ALN-index was evaluated using sample-based alienation coefficients of the current signal. The performance of the algorithm was validated for various scenarios with different fault types at various locations, different fault incident angles, fault impedances, sampling frequencies, hybrid line consisting of overhead (OH) line and underground (UG) cable sections, different types of transformer windings and the presence of noise. Two phase faults with and without the involvement of ground were differentiated using the ground fault index based on the zero sequence current. This study was performed on the IEEE-13 nodes test network to which a solar PV plant with a capacity of 1 MW was integrated. The performance of the algorithm was also tested on the western part of utility grid in the Rajasthan State in India where solar PV energy integration is high. The performance of the algorithm was effectively established by comparing it with the discrete Wavelet transform (DWT), Wavelet packet transform (WPT) and Stockwell transform-based methods.
Highlights
Solar energy (SE) integration into the network of power system networks is continuously increasing to meet the decarbonisation targets
In the event of double phases to the ground fault, the GFI magnitude is high compared to the threshold of the ground fault index (TGFI)
The nature of fault transients may be affected by the type of windings of the transformer installed between the fault location and the relay point which might affect the performance of the protection scheme [25]
Summary
Sheesh Ram Ola 1 , Amit Saraswat 1 , Sunil Kumar Goyal 1, *, S. K. Jhajharia 2 , Baseem Khan 3 , Om Prakash Mahela 4 , Hassan Haes Alhelou 5,6, * and Pierluigi Siano 7, *. Received: 31 January 2020; Accepted: 20 February 2020; Published: 23 February 2020
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