Enerchemical Company has achieved remarkable results in electrical technology upgrades

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Significant Results from Electrical Upgrade at Enehua Company Author/Source: Harmonious Enehua Date: 2020-09-29 Clicks: 121 At 6:12 on September 21, 2020, the company’s two 110kV Huzhong lines were damaged by birds, resulting in an instantaneous single-phase ground fault in phase B; this triggered the operation of the differential current protection and the ground distance protection system； The bus voltage of the 110kV system dropped by 83.77%; the fault duration was 63 ms, and reclosing was successful after a 800 ms delay. The fluctuation in the external power grid caused only slight variations in the current of the liquid oxygen pumps in the two air separation units, as well as the switching of some low-pressure equipment; the production system was not affected by these power fluctuations. The severe voltage fluctuations in the external power grid this time did not affect the production system, mainly because in June of this year, taking advantage of the downtime for dual-series maintenance, the electrical department of the Mechanical, Electrical and Instrumentation Center carried out technical upgrades to the line protection and DC support systems. At 5:38 on August 21, 2019, once again due to seasonal bird damage, phase C of the two 110kV Huzhong lines experienced an instantaneous single-phase ground fault, which caused severe fluctuations in the external power grid. The voltage of the 110kV system bus dropped by 86.68%; the duration of the fault was 58 milliseconds. As a result, both series in the production system were shut down, resulting in economic losses of tens of millions of yuan for the company. In response to this serious issue, Liu Yujun, the supervisor in charge of mechanical, electrical, and instrumentation affairs, organized experts to conduct a review of our company’s power supply system, and identified a series of technical improvement measures, including upgrading the protection systems of 35kV lines to fiber-optic differential protection, as well as adding a DC support system to the liquid oxygen pumps. Taking advantage of the company’s dual-series parking maintenance work in 2020, the electrical department completed the implementation of all the technical improvement plans within one month; after passing the performance tests, the system was put into operation safely. The causes of the two external power grid fluctuations were the same, with similar voltage fluctuation amplitudes and duration of the faults; however, their impact on production was vastly different. The optimization and renovation of the power supply system proved effective in these real-world scenarios, passing performance assessments and yielding significant results.