CN219498953U - Single-phase earth fault processing system of power distribution network - Google Patents

Abstract

The utility model relates to the technical field of power distribution network system ground fault, and discloses a power distribution network single-phase ground fault processing system, which aims to solve the problem that the existing scheme can not comprehensively and effectively process the power distribution network system single-phase ground fault capacitance current, and mainly comprises the following steps: the power distribution network neutral point is grounded through the active intervention type arc suppression device and the arc suppression coil device respectively, the secondary side of the voltage transformer and the secondary side of each zero sequence current transformer are connected with the line selection controller respectively, and the line selection controller is in communication connection with the active intervention type arc suppression device. The utility model realizes comprehensive and effective treatment of the single-phase ground fault capacitance current, improves the power supply reliability of the power distribution network system, avoids the initiation of secondary disasters, and is particularly suitable for a 10kV power distribution network system.

Description

Single-phase earth fault processing system of power distribution network

Technical Field

The utility model relates to the technical field of power distribution network system ground faults, in particular to a power distribution network single-phase ground fault processing system.

Background

At present, the cabling rate of the power distribution network is improved, the capacitance current of the system is increased, if the power distribution network runs for 2 hours with faults, fire disasters are easy to occur, and life and property safety is seriously threatened; the power failure range is enlarged, and the engineering construction progress and quality are seriously affected. By combining with the actual situation of the site, the power distribution network system needs to pay attention to the aspects of fire prevention, safety and the like, ensures that arcing does not occur and eliminates fire hazards. It can be seen that distribution network systems with high demands on arcing and fire tend to quickly and accurately cut or isolate faulty lines.

The existing processing method for generating capacitive current by single-phase earth fault of the power distribution network system generally comprises the following three steps:

first kind: the neutral point of the distribution network is grounded through an arc suppression coil device, and aiming at the problem that the single-phase grounding fault capacitor current is increased to generate flashover, a method of utilizing the electric shock current of the arc suppression coil to counteract the fault point capacitor current is adopted, and the distribution network normally operates in an overcompensation state (generally overcompensation is more than 10 percent), so that the fault point current is reduced to become inductive current, and the arc suppression effect is realized. When permanent faults occur to the overhead line and the cable line and single-phase earth faults occur, the neutral point of the power distribution network is not arc-extinguishing and invalid through the arc-extinguishing coil device, and the system with larger capacitance current cannot achieve good arc-extinguishing effect; but also cannot compensate for high frequency and resistive current components.

Second kind: when a single-phase earth fault occurs, the neutral point of the power distribution network is overlapped to a fault line by current generated by applying the neutral point displacement voltage of the power distribution network to the small resistor, the ground current is amplified, and when the ground current exceeds a certain limit value, zero sequence protection of the fault line is started, and the fault line is cut off. The mode has certain requirements on the grid structure, has limited transition resistance capability, and obviously reduces the power supply reliability when transient faults are frequent.

Third kind: the neutral point of the distribution network is grounded through an active intervention type arc extinction device, and a single-phase grounding fault phase is automatically grounded through a low-excitation impedance transformer for protection. When single-phase grounding faults occur, the device judges the single-phase grounding phase, controls the single-phase grounding circuit breaker of the grounding phase to be switched on, and grounds the grounding phase through the low-excitation impedance transformer. And selecting lines according to the change characteristics of the zero sequence currents of each loop before and after the action. For permanent grounding, the signal generator of the device injects characteristic signals into the grounding phase through the low-excitation impedance transformer, at the moment, the low-excitation impedance transformer is used as a characteristic signal voltage source, and fault location and isolation are carried out by detecting the characteristic signals through the fault indicator and the fault isolation device. And calculating the grounding impedance of the system, if the grounding impedance is restored to the normal state of the system, judging that the grounding fault disappears, and controlling the single-phase grounding circuit breaker to switch off so as to realize the automatic reset function of single-phase grounding protection. However, the power distribution network neutral point has fewer manufacturers of active intervention type arc extinction devices, has fewer application performance and operation experience, and is required to be researched for distinguishing the ground faults with different properties and the operation reliability of the devices.

Disclosure of Invention

The utility model aims to solve the problem that the existing scheme cannot comprehensively and effectively process the single-phase earth fault capacitance current of a power distribution network system, and provides a power distribution network single-phase earth fault processing system.

The technical scheme adopted by the utility model for solving the technical problems is as follows:

a power distribution network single-phase earth fault handling system, the power distribution network comprising: a bus bar, a plurality of feeder lines connected to the bus bar, and a feeder breaker provided on each feeder line, the system comprising: the power distribution network neutral point is respectively grounded through the active intervention type arc suppression device and the arc suppression coil devices, the primary side of the voltage transformer is connected with a bus, the secondary side of the voltage transformer is connected with the line selection controller, one end of each feeder circuit breaker is respectively connected with the bus, the other end of one feeder circuit breaker is connected with the active intervention type arc suppression device, the other end of one feeder circuit breaker is connected with the arc suppression coil device, the other ends of the other feeder circuit breakers except the feeder circuit breaker connected with the active intervention type arc suppression device are respectively connected with the primary side of the zero sequence current transformer, the secondary side of each zero sequence current transformer is respectively connected with the line selection controller, and the line selection controller is in communication connection with the active intervention type arc suppression device.

Further, the transformation ratios of the zero sequence current transformers are consistent.

Further, the bus voltage is 10kV.

Further, the distribution network comprises a section I bus and a section II bus, the section I bus and the section II bus are respectively provided with a single-phase grounding fault processing system of the distribution network, the section I bus and the section II bus are connected through a circuit breaker, and a line selection controller and an active intervention type arc suppression device corresponding to the section I bus are in communication connection with a line selection controller and an active intervention type arc suppression device corresponding to the section II bus.

The beneficial effects of the utility model are as follows: according to the single-phase grounding fault processing system for the power distribution network, disclosed by the utility model, a power distribution network neutral point grounding mode of combining an active intervention type arc suppression device with an arc suppression coil grounding device is adopted, if a single-phase grounding fault occurs, phase selection arc suppression and line selection tripping can be rapidly and effectively carried out, fault lines are cut off or isolated, and further, the comprehensive and effective processing of single-phase grounding fault capacitance current is realized, the reliability of power supply of the power distribution network system is improved, and the initiation of secondary disasters is avoided.

Drawings

Fig. 1 is a schematic structural diagram of a single-phase earth fault handling system of a power distribution network according to an embodiment of the present utility model;

reference numerals illustrate:

PT 1-a first voltage transformer; PT 2-a second voltage transformer; g1-a first active intervention type arc extinguishing device; g2-a second active intervention type arc extinction device; m1-a first arc suppression coil device; m2-a second arc suppression coil device; u1-a first line selection controller; u2-a second line selection controller; QF-circuit breaker; an L-optical fiber; q1-a first feeder breaker; q2-a second feeder breaker; q3-a third feeder breaker; q4-fourth feeder circuit breaker; q5-a fifth feeder breaker; q6-sixth feeder circuit breaker; q7-seventh feeder breaker; q8-eighth feeder circuit breaker; q9-ninth feeder circuit breaker; q10-tenth feeder breaker; CT 1-a first zero sequence current transformer; CT 2-second zero sequence current transformer; CT 3-third zero sequence current transformer; CT 4-fourth zero sequence current transformer; CT 5-fifth zero sequence current transformer; CT 6-sixth zero sequence current transformer; CT 7-seventh zero sequence current transformer; CT 8-eighth zero sequence current transformer.

Detailed Description

Embodiments of the present utility model will be described in detail below with reference to the accompanying drawings.

The embodiment of the utility model provides a single-phase earth fault processing system of a power distribution network, which comprises: a bus bar, a plurality of feeder lines connected to the bus bar, and a feeder breaker provided on each feeder line, the system comprising: the power distribution network neutral point is respectively grounded through the active intervention type arc suppression device and the arc suppression coil devices, the primary side of the voltage transformer is connected with a bus, the secondary side of the voltage transformer is connected with the line selection controller, one end of each feeder circuit breaker is respectively connected with the bus, the other end of one feeder circuit breaker is connected with the active intervention type arc suppression device, the other end of one feeder circuit breaker is connected with the arc suppression coil device, the other ends of the other feeder circuit breakers except the feeder circuit breaker connected with the active intervention type arc suppression device are respectively connected with the primary side of the zero sequence current transformer, the secondary side of each zero sequence current transformer is respectively connected with the line selection controller, and the line selection controller is in communication connection with the active intervention type arc suppression device.

As shown in FIG. 1, in this embodiment, the power distribution network system includes a section I bus and a section II bus, on which the power distribution network single-phase grounding fault processing system is respectively disposed, the section I bus and the section II bus are connected through a breaker QF.

In this embodiment, the feeder circuit breaker that sets up on I section generating line feeder includes: the single-phase ground fault handling system that first feeder circuit breaker Q1, second feeder circuit breaker Q2, third feeder circuit breaker Q3, fourth feeder circuit breaker Q4 and fifth feeder circuit breaker Q5, I section generating line corresponds includes: the system comprises a first voltage transformer PT1, a first zero-sequence current transformer CT1, a second zero-sequence current transformer CT2, a third zero-sequence current transformer CT3, a fourth zero-sequence current transformer CT4, a first active intervention type arc suppression device G1, a first arc suppression coil device M1 and a first connector controller U1. The primary side of the first voltage transformer PT1 is connected with the I section bus, the secondary side of the first voltage transformer PT1 is connected with the first wire connector controller U1, the first feeder circuit breaker Q1, the second feeder circuit breaker Q2, the third feeder circuit breaker Q3, the fourth feeder circuit breaker Q4 and one end of the fifth feeder circuit breaker Q5 are respectively connected with the I section bus, wherein the other end of the first feeder circuit breaker Q1 is connected with the primary side of the first zero sequence current transformer CT1, the other end of the second feeder circuit breaker Q2 is connected with the primary side of the second zero sequence current transformer CT2, the other end of the third feeder circuit breaker Q3 is connected with the primary side of the third zero sequence current transformer CT3, the other end of the fourth feeder circuit breaker Q4 is respectively connected with the primary side of the fourth zero sequence current transformer CT4 and the first arc-extinguishing coil device M1, the other end of the fifth feeder circuit breaker Q5 is connected with the first active interference type arc-extinguishing device G1, the first zero sequence current transformer CT1, the second zero sequence current transformer CT2, the third zero sequence current transformer CT3 and the first wire connector U1 are respectively connected with the first active interference type arc-extinguishing device.

In this embodiment, the feeder circuit breaker disposed on the section ii bus feeder includes: the single-phase ground fault handling system corresponding to the sixth feeder circuit breaker Q6, the seventh feeder circuit breaker Q7, the eighth feeder circuit breaker Q8, the ninth feeder circuit breaker Q9 and the tenth feeder circuit breaker Q10, and the section ii bus includes: the system comprises a second voltage transformer PT2, a fifth zero-sequence current transformer CT5, a sixth zero-sequence current transformer CT6, a seventh zero-sequence current transformer CT7, an eighth zero-sequence current transformer CT8, a second active intervention type arc suppression device G2, a second arc suppression coil device M2 and a second connector controller U2. The primary side of the second voltage transformer PT2 is connected with the section I bus bar, the secondary side of the second voltage transformer PT2 is connected with the second wire connector controller U2, the sixth feeder circuit breaker Q6, the seventh feeder circuit breaker Q7, the eighth feeder circuit breaker Q8, the ninth feeder circuit breaker Q9 and one end of the tenth feeder circuit breaker Q10 are respectively connected with the section II bus bar, wherein the other end of the sixth feeder circuit breaker Q6 is connected with the second active intervention type arc suppression device G2, the other end of the seventh feeder circuit breaker Q7 is respectively connected with the primary side of the fifth zero sequence current transformer CT5 and the second arc suppression coil device M2, the other end of the eighth feeder circuit breaker Q8 is connected with the primary side of the sixth zero sequence current transformer CT6, the other end of the ninth feeder circuit breaker Q9 is connected with the primary side of the seventh zero sequence current transformer CT7, the other end of the tenth feeder circuit breaker Q10 is connected with the primary side of the eighth zero sequence current transformer CT8, the fifth zero sequence current transformer CT5, the seventh zero sequence current transformer CT6, the seventh zero sequence transformer CT7 and the eighth zero sequence coil connector CT8 are respectively connected with the second zero sequence current transformer C2, and the active intervention type arc suppression coil controller U2 is connected with the second zero sequence transformer C2.

The communication connection in this embodiment may be optical fiber communication, that is, the first active intervention type arc extinguishing device G1, the second active intervention type arc extinguishing device G2, the first line selection controller U1 and the second line selection controller U2 are all connected through the optical fiber L.

The transformation ratios of the first zero-sequence current transformer CT1, the second zero-sequence current transformer CT2, the third zero-sequence current transformer CT3 and the fourth zero-sequence current transformer CT4 are consistent, and the transformation ratios of the fifth zero-sequence current transformer CT5, the sixth zero-sequence current transformer CT6, the seventh zero-sequence current transformer CT7 and the eighth zero-sequence current transformer CT8 are consistent. The first line selection controller U1 is used for collecting zero sequence current transformer signals on all feeder lines on the section I bus and three-phase voltage and open triangular voltage signals on the secondary side of the first voltage transformer PT1, and the second line selection controller U2 is used for collecting zero sequence current transformer signals on all feeder lines on the section II bus and three-phase voltage and open triangular voltage signals on the secondary side of the second voltage transformer PT 2.

In practical application, if the section I bus and the section II bus are operated in parallel, namely when the breaker QF is disconnected, the active intervention type arc suppression device and the arc suppression coil grounding device are automatically operated on the same section bus in parallel; if the I section bus and the II section bus are in loop closing operation, namely when the breaker QF is closed, one set of the active intervention type arc suppression devices are automatically locked, and at the moment, the power distribution network system is operated by one of the active intervention type arc suppression devices in parallel with the two arc suppression coil devices.

The following describes the fault processing flow of the utility model by taking a power distribution network as a 10kV system as an example:

(1) The active intervention type arc suppression device is grounded, and the neutral point of the power distribution network is matched with the line selection controller device through the grounding of the arc suppression coil device: if the fault point is a low-resistance fault, the active intervention type arc extinction device completes the rapid transfer of the capacitive current of the fault point within 80ms, and extinguishes the arc. If the fault point is a high-resistance fault, current compensation is firstly carried out by the arc suppression coil, and then the zero sequence voltage is obviously increased until the starting condition of the active intervention type arc suppression device is reached (the zero sequence voltage reaches a threshold value), so that the fault processing is rapidly completed.

(2) When any feeder line fails in single phase to ground:

1) And (3) phase selection and discrimination: when the zero sequence voltage exceeds the threshold value, an active intervention arc extinction device is started, and the single-phase grounding fault phase of the 10kV system is analyzed and judged according to the three-phase voltage, the zero sequence voltage and other parameters of the 10kV system. If the phase selection is wrong, the active intervention type arc extinction device can perform phase reselection until the phase selection is correct.

2) Line selection and judgment: the active intervention type arc suppression device can accurately distinguish fault lines and non-fault lines according to the change of the zero sequence current of the 10kV system, and the accuracy of grounding line selection is ensured.

The zero sequence current of the line is reduced and the zero sequence current is changed from large to small without single-phase earth fault line; the single-phase earth fault line occurs, the current of the single-phase earth fault point is increased, and the zero sequence current of the single-phase earth fault line can change from small to large.

3) Judging the fault type: the active intervention type arc extinction device judges through zero sequence voltage, if the zero sequence voltage disappears, the 10kV system is in instantaneous single-phase grounding fault, and the system is restored to normal operation; if the zero sequence voltage does not disappear, a permanent single-phase earth fault occurs in the 10kV system.

(1) Transient single phase ground fault: when a 10kV line has an instantaneous single-phase grounding fault, the active intervention arc suppression device sends out a command of closing a grounding fault phase, the split-phase circuit breaker closes, the grounding fault phase is in metallic grounding, unstable (intermittent) grounding of the single-phase grounding fault point is converted into special stable metallic grounding in a transformer substation, the relative ground voltage drop of the fault is zero, the grounding fault point is extinguished, and the occurrence of gap grounding fault arc overvoltage and secondary disaster caused by the grounding fault point are avoided.

(2) Permanent single phase ground fault: and according to the line selection result, a tripping command is sent out through a line selection controller to act on a tripping loop of the 10kV line feeder circuit breaker, and a single-phase grounding fault line is instantaneously cut off.

It can be understood that when the active intervention type arc suppression device and the arc suppression coil grounding device are operated in parallel, the current flowing through the fault grounding switch can be reduced, the severe transient process is relieved, the line selection accuracy and the recognition range of the high-resistance grounding fault are improved, the transient impact can be effectively restrained, and the original bus voltage change is protected.

Through the flow, the single-phase grounding fault processing system of the power distribution network adopts the power distribution network neutral point grounding mode of combining the active intervention arc suppression device and the arc suppression coil grounding device, if single-phase grounding faults occur, phase-selecting arc suppression and line-selecting tripping can be rapidly and effectively carried out, fault lines are cut off or isolated, further, comprehensive and effective processing on single-phase grounding fault capacitance current is realized, the reliability of power supply of the power distribution network system is improved, and the initiation of secondary disasters is avoided.

Claims (4)

1. A power distribution network single-phase earth fault handling system, the power distribution network comprising: a bus bar, a plurality of feeder lines connected with the bus bar, and a feeder circuit breaker provided on each feeder line, characterized in that the system comprises: the power distribution network neutral point is respectively grounded through the active intervention type arc suppression device and the arc suppression coil devices, the primary side of the voltage transformer is connected with a bus, the secondary side of the voltage transformer is connected with the line selection controller, one end of each feeder circuit breaker is respectively connected with the bus, the other end of one feeder circuit breaker is connected with the active intervention type arc suppression device, the other end of one feeder circuit breaker is connected with the arc suppression coil device, the other ends of the other feeder circuit breakers except the feeder circuit breaker connected with the active intervention type arc suppression device are respectively connected with the primary side of the zero sequence current transformer, the secondary side of each zero sequence current transformer is respectively connected with the line selection controller, and the line selection controller is in communication connection with the active intervention type arc suppression device.

2. The power distribution network single-phase earth fault handling system of claim 1, wherein the transformation ratios of the zero sequence current transformers are identical.

3. The power distribution network single-phase earth fault handling system of claim 1, wherein the bus voltage is 10kV.

4. The single-phase earth fault processing system of the power distribution network according to claim 1, wherein the power distribution network comprises a section I bus and a section II bus, the section I bus and the section II bus are respectively provided with the single-phase earth fault processing system of the power distribution network, the section I bus and the section II bus are connected through a circuit breaker, and a line selection controller corresponding to the section I bus and an active intervention arc suppression device are in communication connection with a line selection controller corresponding to the section II bus and an active intervention arc suppression device.