A novel protection for powerformers in NIEPS |
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Authors: | Yuanyuan Wang Jinbao JianXiangjun Zeng Lihong LongSidong Liu |
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Affiliation: | a Guangxi University, Nanning Province 530004, China b School of Electrical and Information Engineering, Changsha University of Science and Technology, Hunan Province 410114, China c Hunan Electric Power Design Institute, Hunan Province 410007, China |
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Abstract: | A new type of high-voltage generator which offers a direct connection to the power network without the need for a step-up transformer is called powerformer. The neutral of the most powerformers is unearthed which belongs to NIEPS. When a stator single phase-to-ground fault occurs in a powerformer, every generator that is connected in parallel with the faulty powerformer has the same voltage. Traditional protection schemes using zero sequence voltage and third-harmonic voltage signals cannot detect which powerformer is faulted. In order to solve this problem for powerformer protection, a novel stator single phase-to-ground fault protection based on the direction and magnitude of zero-sequence currents is proposed in this paper. Simulation results have shown that, under different fault conditions, the new scheme can distinguish reliably internal faults from external faults, and can detect stator single phase-to-ground fault occurred in which powerformer with resistance 1 kΩ. A 100% of the winding can be fully protected. |
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Keywords: | Protection Powerformer Stator single phase-to-ground fault Zero-sequence fundamental component Third-harmonic fault component |
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