The method of extracting the zero-sequence voltage when single-phase grounding of distribution network based on two single-phase voltage transformers

Abstract

The present invention is a method based on two single-phase voltage transformers to extract the zero-sequence voltage of a distribution network when a single-phase is grounded. VV2 formation, t1 and t2 time selection principles, electrical measurement Vp1 and Vp2 acquisition time and sampling rate determination, calculation of zero-sequence voltage vector and other steps. The method is scientific and reasonable, simple and easy to implement, the cost of obtaining zero-sequence voltage is low, and the physical size of related equipment can be reduced. It is suitable for a power distribution network system including multiple outgoing lines and a busbar, so as to perform grounding in the event of a single-phase grounding fault Line selection protection.

Description

technical field [0001] The invention relates to a grounding detection technology of a power distribution network, in particular to a method for extracting a zero-sequence voltage when a single-phase grounding of a power distribution network is based on two single-phase voltage transformers. Background technique [0002] my country's 10kV distribution network has a large number, wide distribution range, low equipment insulation level, and is susceptible to various faults caused by the internal factors of the power grid and the external natural environment; among them, the probability of single-phase ground faults is the highest, which can account for the total faults. About 80% of it. When a single-phase ground fault occurs in the distribution network, the line voltage between the three phases is still symmetrical, and the fault current is small, which does not affect the continuous power supply to the load, and does not need to trip immediately. The regulations stipulate that...

AI Technical Summary

Problems solved by technology

[0003] One of the characteristics of ground fault occurrence, zero-sequence voltage is an important characteristic quantity for ground fault detection, alarm and processing; with the rapid development of urban distribution network scale, the requirements for automatic control technology and level are getting higher and higher, outdoor automatic The scope of application of measurement and control equipment such as FTU and intelligent high-voltage electrical appliances continues to expand; due to the limitations of various reasons for the installation of outdoor automatic measurement and control equipment, no zero-sequence voltage transformer is installed, but only simple single-phase voltage transformers and single line voltage The transformer cannot obtain the zero-sequence voltage; it brings great difficulties to the detection, alarm and processing of the ground fault for the outdoor automatic measurement and control equipment

So far, there have been no literature reports and practical applications of the method based on two single-phase inductors to extract the zero-sequence voltage of the ground fault