Single-phase-to-earth fault processing device and method for neutral non-effectively grounded distribution network

Patent metadata

Field	Value
Publication number	US-10148080-B2
Application number	US-201415022183-A
Country	US
Kind code	B2
Filing date	Sep 10, 2014
Priority date	Sep 16, 2013
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

A single-phase-to-earth fault processing device for a neutral non-effectively grounded distribution network includes a split-phase arc quenching device connected between earth and a three-phase bus of the distribution network, and a controller with an input end connected with a single-phase-to-earth phase selection device of the distribution network. The split-phase arc quenching device includes a multiphase switching device which operates independently for each phase, and a fuse connected in series with the multiphase switching device. The controller is for controlling opening and closing of three single-phase switches in the multiphase switching device. A single-phase-to-earth fault processing method firstly controls the split-phase arc quenching device to preprocess the fault. If the fault still exists, through a ground resistor a zero-sequence current is generated on a fault line. After delaying to wait for a line to isolate a fault section, a ground connection of the neutral is cut to restore the distribution network.

First claim

What is claimed is:

1. A single-phase-to-earth fault processing device for a neutral non-effectively grounded distribution network, comprising: a split-phase arc quenching device connected between earth and a three-phase bus of the distribution network; and a controller with an input end connected with a single-phase-to-earth phase selection device of the distribution network; wherein: said split-phase arc quenching device comprises a multiphase switching device which operates independently for each phase, and a fuse which is connected in series with said multiphase switching device; and said controller is for controlling opening and closing of three single-phase switches, corresponding to the three-phase bus, in said multiphase switching device;
said multiphase switching device is a vacuum breaker or a vacuum contactor, which operates independently for each phase;
the single-phase-to-earth fault processing device further comprises a ground resistor connected with a neutral of the distribution network, and a ground resistor switch arranged on a connection line of said ground resistor;
said ground resistor has a resistance of 5.5-70 Ohms; and said ground resistor switch is a single-phase vacuum breaker or a single-phase vacuum contactor; and
said controller is further for controlling opening and closing of said ground resistor switch.

2. The single-phase-to-earth fault processing device for the neutral non-effectively grounded distribution network, as recited in claim 1 , wherein: said ground resistor and said ground resistor switch are connected in series and arranged between the neutral on a low-voltage side of a transformer of the distribution network and the earth; and, when a low-voltage winding of the transformer is in a triangle connection, an exclusive ground transformer is adopted to form the neutral.

3. A single-phase-to-earth fault processing method for a neutral non-effectively grounded distribution network, with the single-phase-to-earth fault processing device for the neutral non-effectively grounded distribution network as recited in claim 2 , comprising steps of:
1) when a single-phase-to-earth fault occurs in the distribution network, receiving, by the controller, a fault warning and a phase selection signal, sent from the single-phase-to-earth phase selection device of the distribution network; sending a closing instruction to the single-phase switch, corresponding to the phase selection signal, in the split-phase arc quenching device, so as to ground a bus of a corresponding phase; and, after delaying for 1-2 s, sending an opening instruction to the single-phase switch which is closed; and
2) after opening the corresponding single-phase switch, if the single-phase-to-earth phase selection device no longer sends the fault warning and the phase selection signal, determining the single-phase-to-earth fault to be transient and cleared, and restoring a normal operation state of the distribution network; and
if the single-phase-to-earth phase selection device continues sending the fault warning and the phase selection signal, determining the single-phase-to-earth fault to be permanent; sending the closing instruction to the ground resistor switch by the controller; after closing the ground resistor switch, grounding the neutral of the distribution network through the ground resistor; generating a zero-sequence current over a zero-sequence overcurrent constant value on a fault line; delaying for 5-10 s to wait for a line to automatically finish isolating a fault section; sending the opening instruction to the ground resistor switch; after opening the ground resistor switch, finishing isolating the single-phase-to-earth fault of the distribution network, and restoring a normal operation state of the distribution network.

Assignees

• State Grid Corp China
• State Grid Shaanxi Electric Power Res Institute

Inventors

• Liu Jian
• Li Pinde
• Zhang Xiaoqing
• Zhang Zhihua
• Zhao Shuren

Classifications

• H01H9/54

  Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere · CPC title

• H01H89/00

  Combinations of two or more different basic types of electric switches, relays, selectors and emergency protective devices, not covered by any single one of the other main groups of this subclass · CPC title

• H02H7/26

  Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured (locating faults in cables G01R31/08) · CPC title

• H02H3/167 Primary

  combined with other earth-fault protective arrangements · CPC title

• H01H33/66

  Vacuum switches · CPC title