Abstract
The rapid growth of grid integrated renewable energy (RE) sources resulted in development of the hybrid grids. Variable nature of RE generation resulted in problems related to the power quality (PQ), power system reliability, and adversely affects the protection relay operation. High penetration of RE to the utility grid is achieved using multi-tapped lines for integrating the wind and solar energy and also to supply loads. This created considerable challenges for power system protection. To overcome these challenges, an algorithm is introduced in this paper for providing protection to the hybrid grid with high RE penetration level. All types of fault were identified using a fault index (FI), which is based on both the voltage and current features. This FI is computed using element to element multiplication of current-based Wigner distribution index (WD-index) and voltage-based alienation index (ALN-index). Application of the algorithm is generalized by testing the algorithm for the recognition of faults during different scenarios such as fault at different locations on hybrid grid, different fault incident angles, fault impedances, sampling frequency, hybrid line consisting of overhead (OH) line and underground (UG) cable sections, and presence of noise. The algorithm is successfully tested for discriminating the switching events from the faulty events. Faults were classified using the number of faulty phases recognized using FI. A ground fault index (GFI) computed using the zero sequence current-based WD-index is also introduced for differentiating double phase and double phase to ground faults. The algorithm is validated using IEEE-13 nodes test network modelled as hybrid grid by integrating wind and solar energy plants. Performance of algorithm is effectively established by comparing with the discrete wavelet transform (DWT) and Stockwell transform based protection schemes.
Highlights
Adverse environmental impacts of fossil fuel based power plants have forced the utilities to integrate clean energy with the grid in order to meet future energy demands
This section firstly elaborates the impacts of faulty events on performance of the hybrid grid and requirement of protection schemes
To investigate the impacts of faulty events on the performance of hybrid grid, root mean square (RMS) voltage at the node 650, frequency, power injected by solar PV system and wind power plant into the hybrid grid during the event of phase to ground (PG) fault at node 646 at 6th cycle are illustrated in Figure 4a–d, respectively
Summary
Adverse environmental impacts of fossil fuel based power plants have forced the utilities to integrate clean energy with the grid in order to meet future energy demands. Fast development of renewable technologies and government incentives to reduce carbon footprints have motivated the utilities to switch from the conventional power plants to the renewable energy (RE) generation sources [1] This is achieved by forming the hybrid grid with multi-tapped transmission and sub-transmission lines to supply the loads and integrate RE sources such as wind and solar power plants. Formation of hybrid grids using multi-tapped lines provide economic solutions for RE integration to the grid; it creates protection challenges due to variable nature of RE generation and bidirectional flow of power in the lines This resulted in the requirement of new protection schemes, which can be deployed in the recent structure of hybrid grids for effective protection. A detailed study of challenges associated with the protection of grid integrated distributed generation (DG)
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