Stator earth fault detection & evaluation of delaminated stator bar ground wall-insulation of generator G-4 of HPP Chhukha – A case study

Authors

  • Rinchen Wangdi Druk Green Power Corporation Limited
  • Deepen Sharma Druk Green Power Corporation Ltd
  • Tshewang Dorji Druk Green Power Corporation Limited
  • Tenzin Chophel Druk Green Power Corporation Limited
  • Ugyen Tobgay

DOI:

https://doi.org/10.17102/bjrd.rub.10.2.014

Keywords:

Delamination, dielectric strength, HV DC ramp, insulation resistance, stator earth fault

Abstract

Protective devices are employed to monitor and isolate the faulty equipment whenever faults occur in the power system. In the generator protection system, a conventional stator earth fault protection, which is based on residual over voltage (aka neutral voltage displacement) principle, is observed to be inadequate. The paper thus, discusses on how helpful a modern approach of 100% stator earth fault protection scheme is, and proven effective in generator G- 4 of Chhukha Hydropower Plant (CHP). Also, to assess the health of stator windings, insulation resistance (IR) measurement is the foremost test that needs to be performed to qualify for go- ahead with other insulation tests. HV DC ramp and tan ẟ tests are not uncommon as the tests have been proven useful in evaluating the condition of the groundwall insulation of stator coils. Therefore, this paper also illustrates on investigation and analysis of the test results obtained for a bar, suspected to have groundwall insulation breakdown, due to a number of factors. The test results obtained are compared with that of the other test specimens.

Author Biographies

Rinchen Wangdi, Druk Green Power Corporation Limited

Rinchen Wangdi received Bachelor of Engineering in Electronics & Comm. Engineering from Visveswaraiah Technological University, India in 2009, and Master of Engineering Electrical & Software Systems Engineering from The Sirindhorn International Thai-German Graduate School of Engineering, Thailand in 2019. In his professional career, he was largely involved in looking after the control & protection system of HPP Chhukha and played the role of the team lead in overseeing the activities associated with the control & monitoring, and protection systems of Mangdechhu HEP during the design & review phase. His area of interest includes power system stability & protection. He authored a paper titled ‘Power system stabilizer tuning by incorporating WECC criterion into particle swarm optimization, which was subsequently published at the international conference iEECON2019. He also served at the Centre of Excellence for Automation, Control & Protection, under Hydropower Research & Development Centre (HRDC), and currently, he is the Head, Maintenance Division, Kurichhu Hydropower Plant, DGCP, Mongar.

Deepen Sharma, Druk Green Power Corporation Ltd

Deepen Sharma has Bachelors of Technology in Electrical Engineering from National Institute of Technology, Allahabad, India (2003) and Masters of Technology in Power Electronics, Machines & Drives from the Indian Institute of Technology, New Delhi, India (2007). His professional career started in Ferro Alloys industries before joining Druk Green Power Corporation Ltd. (DGPCL), Bhutan in 2011. He joined as a testing engineers in the Centre of Excellence for Automation, Control & Protection (CoEACaP), Hydropower R&D Centre and currently heading the division, since 2015. He currently overlooks the working and management of CoEACaP, providing guidance in areas pertaining to electrical automation, control and protection. Mr. Sharma has authored/co-authored technical papers on switched mode power electronic converters in IEEE Conferences, PEDES’06, PEDS’07 & Journal of Power Electronics, 2007. A work on the power system modelling of a hydropower plant in Bhutan was presented in the 5th IYCE Conference 2015, Pisa, Italy and published in 2015 IEEE proceedings. His current research interest includes power system modelling and primary electrical systems.

Tshewang Dorji, Druk Green Power Corporation Limited

Tshewang Dorji received Diploma in Electrical Engineering from erstwhile Royal Bhutan Polytechnic in 2001 & subsequently joined the Kurichhu Project Authority. In little more than 15 years of tenure, he was involved widely in maintenance & operation aspects at HPP Kurichhu. Since 2016, he has been serving as a testing engineer at the Centre of Excellence for Automation, Control & Protection, Hydropower R&D Centre. His is specializing in insulation diagnostic testing of the high voltage (HV) equipment of the power system, the area for which he is currently the in-charge.

Tenzin Chophel, Druk Green Power Corporation Limited

Tenzin Chophel received a B.E. degree in electrical engineering from the College of Science and Technology, Royal University of Bhutan, Bhutan in 2010, and the masters in Electrical and Software System Engineering from The Sirindhorn International Thai–German Graduate School of Engineering (TGGS), King Mongkut's University of Technology North Bangkok (KMUTNB), Thailand, in 2019. He joined the Chhukha Hydropower plant, DGPC in 2010, as an Assistant Engineer. He is a maintenance engineer looking after generators, generator transformers, and its auxiliaries of CHP. He has authored a paper on condition assessment of generator insulation using the diagnostic test in iEECON - 2019. He has been also authoring papers in the earlier technical conferences held across DGPC. His current research interest includes condition assessment of generators and partial discharge in a generator. He is now heading Generator Maintenance Unit, Maintenance Division in Chhukha Hydropower Plant, DGPC.

Ugyen Tobgay

Ugyen Tobgay has a Bachelor of Technology in Electrical Engineering from Maulana Azad National Institute of Technology, Bhopal, India (2012). He joined Druk Green Power Corporation Ltd. (DGPCL), Bhutan in 2014, as an Assistant Engineer in the Control & Protection Unit (C&P), Maintenance Division, Chhukha Hydropower Plant (CHP). Prior to joining DGPC, he worked in Punatshangchhu-II Hydroelectric Authority as an Assistant Engineer in Electro-mechanical Circle for almost two years. Mr. Ugyen has authored/co-authored a technical paper on Polarity of Transformers at the 2nd DGPC Technical Conference, 2018.

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Published

01-04-2022

How to Cite

Wangdi, R. ., Sharma, D. ., Dorji, T. ., Chophel, T. ., & Tobgay, U. . (2022). Stator earth fault detection & evaluation of delaminated stator bar ground wall-insulation of generator G-4 of HPP Chhukha – A case study. Bhutan Journal of Research and Development. https://doi.org/10.17102/bjrd.rub.10.2.014

Issue

2022: SPECIAL EDITION

Section

Articles