In recent years, two series reactor faults occurred when a 35kV shunt capacitor bank was cut by a circuit breaker in a 500kV substation in Shenzhen. The reason is analyzed that the large inrush current and overvoltage generated during the switching process caused interturn short circuit fault of the reactor, which seriously threatens the safe operation of the system. To avoid such faults, intelligent phase-controlled short-circuit breakers were used to suppress the closing inrush current and reduce the probability of reignition. To verify the effectiveness of the technology, this paper introduces the causes of switching inrush current and over-voltage and the principle of phase-controlled suppression technology, and then applies the technology to a 500kV substation in Shenzhen. Multiple switching tests are carried out on the intelligent and ordinary circuit breakers respectively. The results show that the maximum inrush current generated by the ordinary circuit breaker is 4.2p.u., and the overvoltage is 1.81p.u. While the maximum inrush current of the intelligent phase-controlled circuit breaker is 2.3p.u., and the overvoltage is 1.4p.u. The results confirm that the application of the intelligent phase-controlled switching technology can suppress the inrush current and overvoltage, thus fundamentally improving the reactive switching efficiency and system safety.
The running of subway rail transit can generate stray currents. This is a current that causes severe corrosion of the buried metal near the subway, and also generates DC bias, which affects nearby power transformers. There are few studies related to the influence of DC bias created by stray current on power transformers. This makes it difficult to determine the impact of subway rail transit on the DC bias of nearby power transformers. To explain the effect of stray current on the DC bias of the power transformer, the characteristics, master sheets of stray current and the principle of DC bias of stray current are analyzed, and a power transformer model of stray current generating exciting current is established. The harmonic components in the stray current are simulated and analyzed. The simulation results show that the track insulation aging caused by subway operation will generate stray current, which will flow into the grounding grid and cause DC bias of the neutral grounding transformer, and then make the transformer core saturated. The amplitude of harmonic component and excitation current will increase with the increase of stray current.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.