Online earth fault positioning system for power distribution network

Abstract

The invention discloses an online earth fault positioning system for a power distribution network. The online earth fault positioning system comprises a monitoring center, a transformer substation signal injection unit, a feeder line branch positioning unit and a distribution transformation monitoring terminal, wherein the monitoring center conducts data exchange with the transformer substation signal injection unit and the feeder line branch positioning unit to achieve the functions of operating data management, logical judgment and fault removal control; the transformer substation signal injection unit achieves the functions of earth fault detection, fault phase distinguishing, special signal injection, fed-out line signal detection and line selection; the feeder line branch positioning unit and the distribution transformation monitoring terminal achieve the functions of branch data acquisition, data exchange with the monitoring center, branch earth fault removal and accurate positioning of an earth point. By means of the online earth fault positioning system for the power distribution network, accurate positioning of an online single-phase earth fault can be realized, a fault section can be removed an isolated as quickly as possible after the earth fault occurs, as a result, security threats to electrical equipment and personnel due to the earth fault are avoided, and power supply reliability is improved.

Description

technical field [0001] The invention belongs to the technical field of electric power distribution network automation, and in particular relates to a grounding fault location system of a distribution network. Background technique [0002] In my country's 6-66 kV distribution network, the neutral point is not grounded and the arc-suppression coil grounding method is mainly used, and a small number of high-resistance grounding methods are used, all of which belong to the small current grounding system. In these grids, single phase-to-earth fault is one of the most common faults. After the single-phase permanent grounding of the low-current grounding system, no short-circuit loop is formed, there is no large-scale short-circuit current, and the voltage between the three-phase lines is still a symmetrical voltage, which does not affect the normal operation of the load and can continue to run for a period of time. However, because the fault signal is weak, and the fault mostly o...

AI Technical Summary

Problems solved by technology

However, the voltage of non-grounded phase-to-ground will increase, and arc overvoltage will be generated when continuous arc is grounded. Long-term operation may damage its insulation and cause serious phase-to-phase faults

Single-phase grounding must try to find the fault point and eliminate it, otherwise, it will pose a threat to the safety of electrical equipment and easily develop into other accidents. These threats include: (1) single-phase grounding current passing through the iron core (such as condensers, Transformer core) will burn out the core

(2) In the vicinity of the fault point of single-phase grounding, the person is in danger of being subjected to step voltage

It is of course dangerous for the human body to be subjected to step voltage

(3) It is easy to develop into a two-phase short circuit

(4) The existence of the grounding point will also make the sheath of the faulty equipment (such as the sheath of the cable) or shield electrified, which may easily cause personal electric shock accidents

Therefore, when a single-phase ground fault occurs, the human body is in danger of being exposed to contact voltage when touching the skin of the faulty equipment.

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