Rapid isolation protection device for ground fault of neutral point ungrounded system of power grid

Abstract

The utility model relates to the technical field of enterprise power grid operation and maintenance, in particular to a rapid isolation protection device for a grounding fault of a power grid neutral point ungrounded system, and aims to solve the problems that when the grounding fault of the power grid neutral point ungrounded system is processed at present, grounding is relieved by generally adopting an arc-extinguishing and resonance-eliminating mode of manually resetting a rapid switch; and a large-area power failure accident is caused by breakdown and short circuit of an insulation weak point of equipment in a system due to too long processing time. According to the device, a fault point is isolated through zero-sequence power direction protection action tripping, closing of the vacuum circuit breaker is converted into metal grounding through action of the quick switch arc-extinguishing and resonance-eliminating circuit, and quick fault isolation is effectively realized through automatic resetting and delay setting functions of the arc-extinguishing and resonance-eliminating circuit. Therefore, the repeated action of the rapid switch arc-extinguishing and resonance-eliminating circuit caused by intermittent arc grounding is avoided, the occurrence rate of large-area power failure accidents caused by arc grounding is greatly reduced, and the safe and stable operation of an enterprise power grid is further ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to enterprise power grid operation and maintenance technical field, concretely relates to a quick isolation protection device of neutral point ungrounded system grounding fault in power grid. BACKGROUND

[0002] The neutral point ungrounded system is widely used in the domestic because of high power supply reliability, but under the neutral point ungrounded mode, the electromagnetic voltage transformer of enterprise power grid will occur ferroresonance overvoltage due to magnetic saturation, and its value can reach 4 times of phase voltage, when intermittent arc grounding occurs, at this time, the grounding arc will be extinguished temporarily at the current zero, and reignite near the peak, and the reignition and extinction of arc will lead to strong electromagnetic oscillation of power grid, and 3.5-4 times of phase voltage can be generated, when the overvoltage duration is relatively long, it will have a great impact on the insulation life of enterprise power grid equipment. In order to prevent overvoltage, the enterprise power grid usually adopts the fast switch arc extinguishing and harmonic elimination device to suppress overvoltage, realizes zero sequence power direction protection isolation fault point, when the system occurs single-phase arc grounding fault, the zero sequence power direction protection operates circuit breaker to trip isolation fault point, and the fast switch arc extinguishing and harmonic elimination device operates vacuum circuit breaker to close the system to metal grounding, which can prevent arc grounding fault development as much as possible, and the whole process needs to manually reset the fast switch arc extinguishing and harmonic elimination device to remove grounding, but it is easy to cause the weak insulation of system equipment to click through and form interphase short circuit, and cause large-area power failure accident due to the long manual reset operation time of personnel and other factors, therefore, it is necessary to further optimize the circuit and device for quickly isolating fault under the condition of single-phase grounding of neutral point ungrounded system, and ensure that the enterprise economic loss is minimized. UTILITARIAN CONTENT

[0003] The utility model provides a kind of quick isolation protection device of neutral point ungrounded system grounding fault in power grid to solve the problems in the above background.

[0004] In order to realize the above purpose, the utility model adopts the following technical solutions:

[0005] The utility model discloses a kind of quick isolation protection devices of power grid neutral point ungrounded system grounding fault, including main bus, one end of main bus is connected with first circuit breaker, first circuit breaker is connected with multiple groups of first current transformer, current transformer is connected to zero sequence transformer, the first circuit breaker, first current transformer and zero sequence transformer constitute feed-out open circuit, the other end of main bus is connected with second circuit breaker, second circuit breaker is connected with multiple groups of second current transformer, the output end of second current transformer is connected to voltage transformer high-voltage fuse and split-phase control fast vacuum circuit breaker, the output end of voltage transformer high-voltage fuse is connected to voltage transformer, and the output end of voltage transformer and split-phase control fast vacuum circuit breaker is connected to fast switch arc-extinguishing harmonic elimination controller, and the second circuit breaker, voltage transformer high-voltage fuse, voltage transformer and fast switch arc-extinguishing harmonic elimination controller constitute fast switch arc-extinguishing harmonic elimination circuit.

[0006] Further, the output end of the second current transformer and the voltage transformer high-voltage fuse are connected in parallel with an electric display and an overvoltage protector.

[0007] Further, the voltage transformer is further connected with a semiconductor self-limiting current strong damping suppressor.

[0008] The utility model has the following beneficial effects:

[0009] The utility model provides a kind of quick isolation protection devices of power grid neutral point ungrounded system grounding fault, by zero sequence power direction protection action tripping isolation fault point, by fast switch arc-extinguishing harmonic elimination circuit action, make vacuum circuit breaker closing turns into metal grounding, again through arc-extinguishing harmonic elimination circuit automatic reset and delay setting function, effectively realize quick isolation fault, avoid the repeated action of fast switch arc-extinguishing harmonic elimination circuit caused by intermittent arc grounding, greatly reduce the large-area power failure accident incidence caused under arc grounding condition, and further ensure the safe and stable operation of enterprise power grid, solve the problem that when handling power grid neutral point ungrounded system grounding fault, since the mode of manually resetting fast switch arc-extinguishing harmonic elimination is generally adopted to remove grounding, it is extremely vulnerable to processing time being too long, finally cause system equipment insulation weak click-through and short circuit, cause large-area power failure accident. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 It is whole structure connection schematic diagram of the utility model.

[0011] The meanings of the reference signs are as follows:

[0012] 1, main bus; 2, first circuit breaker; 3, first current transformer; 4, voltage transformer high-voltage fuse; 5, live display; 6, voltage transformer; 7, semiconductor self-limiting strong damping suppressor; 8, split-phase control fast vacuum circuit breaker; 9, overvoltage protector; 10, zero sequence transformer; 11, zero sequence power direction protection; 12, fast switch arc extinction harmonic elimination controller 13, second circuit breaker; 14, second current transformer. DETAILED DESCRIPTION

[0013] The utility model will be further described below in combination with the drawings and specific embodiments.

[0014] As Figure 1 shown, a kind of fast isolation protection device of grounding fault of power grid neutral point ungrounded system, including main bus 1, one end of main bus 1 is connected with first circuit breaker 2, first circuit breaker 2 is connected with multiple groups of first current transformer 3, current transformer 3 is connected to zero sequence transformer 10, the first circuit breaker 2, first current transformer 3 and zero sequence transformer 10 constitute feed-out open circuit, another end of the main bus 1 is connected with second circuit breaker 13, second circuit breaker 13 is connected with multiple groups of second current transformer 14, the output end of second current transformer 14 is connected to voltage transformer high-voltage fuse 4 and split-phase control fast vacuum circuit breaker 8, the output end of voltage transformer high-voltage fuse 4 is connected to voltage transformer 6, and the output end of voltage transformer 6 and split-phase control fast vacuum circuit breaker 8 is all connected to fast switch arc extinction harmonic elimination controller 12, and the second circuit breaker 13, voltage transformer high-voltage fuse 4, voltage transformer 6 and fast switch arc extinction harmonic elimination controller 12 constitute fast switch arc extinction harmonic elimination circuit.

[0015] The output end of second current transformer 14 and the voltage transformer high-voltage fuse 4 are connected with live display 5 and overvoltage protector 9 in parallel.

[0016] Voltage transformer 6 is also connected with semiconductor self-limiting strong damping suppressor 7.

[0017] Zero sequence power direction protection 11 includes grounding point zero sequence current, zero sequence voltage value, zero sequence power direction and time limit etc., and fast switch arc extinction harmonic elimination circuit includes zero sequence voltage, fault phase voltage and non-fault phase voltage value etc.

[0018] The utility model discloses in the specific application, the quick switch arc elimination harmonic elimination circuit is connected in the system main bus 1, when the arc light ground of the feed-out open circuit of main bus 1 is connected with the occurrence, the zero sequence power direction protection 11 of the zero sequence mutual inductor 10 of feed-out open circuit configuration and quick switch arc elimination harmonic elimination controller 12 start simultaneously, zero sequence power direction protection 11 gathers the sampling current of zero sequence mutual inductor 10 of feed-out open circuit, action trip removes first circuit breaker 2 and isolates the fault, and quick switch arc elimination harmonic elimination circuit gathers the sampling voltage of voltage mutual inductor 6, and control split -phase control quick vacuum circuit breaker 8 fault phase closing, will arc light ground change into metallic property ground, to reach the purpose of restraining overvoltage.

[0019] After quick switch arc elimination harmonic elimination circuit control split -phase control quick vacuum circuit breaker 8 closing, will arc light ground change into metallic property ground, delay 8s, and quick switch arc elimination harmonic elimination circuit automatic return once, and after automatic return once, again delay 5min and carry out once automatic setting, reset to automatic return logic, after quick switch arc elimination harmonic elimination circuit automatic return once, again occur ground fault in reset delay time, and quick switch arc elimination harmonic elimination circuit sends action instruction, no longer carries out automatic reset, when automatic delay setting procedure does not start again, must return manually in situ or remote background, can restore the initial state of quick switch arc elimination harmonic elimination circuit, after quick switch arc elimination harmonic elimination circuit automatic return, no single-phase ground fault occurs in reset delay time, and quick switch arc elimination harmonic elimination circuit automatic setting, and restore its initial state, thereby effectively realized quick isolation fault, avoided the repeated action of quick switch arc elimination harmonic elimination circuit under the condition of intermittent arc light ground, greatly reduced the large area power failure accident incidence caused under arc light ground, further ensured the safe and stable operation of enterprise power network, therefore, the device has good practicality.

Claims

1. A device for fast isolation protection of a ground fault in an ungrounded system of a power grid neutral point, comprising a main bus (1), characterized in that: One end of the main bus (1) is connected with the first circuit breaker (2), the first circuit breaker (2) is connected with multiple groups of the first current transformer (3), the first current transformer (3) is connected to the zero sequence transformer (10), the first circuit breaker (2), the first current transformer (3) and the zero sequence transformer (10) constitute a feeder open circuit, the other end of the main bus (1) is connected with the second circuit breaker (13), the second circuit breaker (13) is connected with multiple groups of the second current transformer (14), the output end of the second current transformer (14) is connected to the voltage transformer high-voltage fuse (4) and the split-phase control fast vacuum circuit breaker (8), the output end of the voltage transformer high-voltage fuse (4) is connected to the voltage transformer (6), and the output end of the voltage transformer (6) and the split-phase control fast vacuum circuit breaker (8) is connected to the fast switch arc extinction harmonic elimination controller (12), and the second circuit breaker (13), the voltage transformer high-voltage fuse (4), the voltage transformer (6) and the fast switch arc extinction harmonic elimination controller (12) constitute a fast switch arc extinction harmonic elimination circuit.

2. The device for fast isolation of ground fault in the neutral non-grounded system of power network according to claim 1, characterized in that it further comprises: The output end of the second current transformer (14) and the voltage transformer high-voltage fuse (4) are connected in parallel with the electric display (5) and the overvoltage protector (9).

3. The device for fast isolation of ground fault in an ungrounded neutral system of power grid according to claim 1, characterized in that: The voltage transformer (6) is further connected with the semiconductor self-limiting current strong damping suppressor (7).

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