DETERMINING OPTIMAL METHODS AND STANDARD OF DIAGNOSING, TESTING FOR MEDIUM VOLTAGE UNDERGROUND CABLE IN HO CHI MINH CITY POWER GRID

Abstract

This paper proposes the diagnosing and testing methods for medium voltage underground cables. There are two main classifications depending on the cut-down power source status: Off-line (Cut-off Power source) and On-line (Testing without cutting off electricity). After researching and collecting knowledges from international standards such as: IEC, IEEE, CIGRE, as well as reference papers, this paper suggests replacing the testing procedure of underground cable XLPE in Ho Chi Minh City for upgrading test results without harming the tested objects. This paper also combined data collected from installing, repairing, testing cables on-site of EVNHCMC from 2016-2019. Then, the authors recommend diagnosing and testing standard for underground cable that operating in EVNHCMC. This helps the power companies unify 3 main levels to handle cables: reoperation allowance, weakening point replacement in 6/12 month periods; immediate repair. Based on this change of testing procedures and testing standards, the numbers and percentages of cables’ faults have been decreased steadily year by year, which helps improve the reliability of electricity supply, since 2016 in EVNHCMC.