CN215601029U - Three-phase non-effective grounding power supply system convenient for fault treatment - Google Patents

Abstract

The utility model discloses a three-phase non-effective grounding power supply system convenient for fault treatment.A circuit breaker is arranged on an outgoing line, a plurality of controlled switches are arranged below the circuit breaker, the controlled switches can detect current information of each phase and can cut off a circuit according to the current information, and at least one section of differential protection area is arranged on the outgoing line; a first switch is arranged on an outgoing line, a third switch is arranged at the lower port of the circuit breaker, a second switch is arranged on a bus or a system neutral point, the second switch is communicated with the ground through a variable resistance box, and the second switch can be used for connecting any one of two phases or three phases of the bus with the ground or connecting the system neutral point with the ground. The system can fully utilize the rapid advantage of differential protection aiming at the circuit with differential protection, can rapidly position the interphase short-circuit fault point interval in the area without differential protection, and can automatically, rapidly and accurately remove the fault.

Description

Three-phase non-effective grounding power supply system convenient for fault treatment

Technical Field

The utility model relates to the field of fault processing of power supply systems, in particular to a three-phase non-effective grounding power supply system convenient for fault processing.

Background

When interphase short circuit occurs on a three-phase non-effective grounding power supply system, the fault can be quickly removed by adopting a differential protection mode. The differential protection is to use the current comparison between the electric energy inlet switch and a plurality of electric energy outlet switches, and when the difference value of the sum of the inlet current and the outlet current is larger than the threshold value, the differential protection is tripped to cut off the fault in the differential protection area. But the differential protection cannot handle faults outside the differential protection zone. For a line without a differential protection zone, the following method can be generally adopted to deal with the fault: 1. the reclosing mode is adopted: the first breaker on the line is cut off firstly and then closed, if the first breaker is a transient phase-to-phase short circuit and is eliminated after the first breaker is closed, normal power supply is continued. And if the interphase short-circuit fault still exists after the first breaker is closed, the first breaker is cut off to wait for maintenance. 2. Adopting a time step difference matching method: the method can isolate the fault area, but for the fault with the fault point close to the power supply, the short-circuit current tolerance time is long, and the impact on the power grid is large. 3. The first breaker is tripped after overcurrent, then the breaker is tripped at the last, if the fault occurs below the last breaker, the fault can be eliminated, otherwise, the first breaker is overlapped, and the fault current still exists, the first breaker is tripped after overcurrent, then the last but one breaker is cut off, if the interphase short circuit occurs between the last but one breaker and the last breaker, the fault can be eliminated, and by analogy, the breakers are sequentially and upwards cut off until the fault is eliminated. During this operation, however, the circuit breaker, which is not switched off, is constantly subjected to a large short-circuit current surge, which, if left for too long, can cause damage to the line. If the duration of the inter-phase short circuit cannot exceed 300 milliseconds and the tripping time of the circuit breaker is 100 milliseconds, generally, more than three circuit breakers are not suitable for the line, otherwise, the method can cause the impact of the line exceeding 300 milliseconds.

For better fault treatment of a line provided with a differential protection area, the structure of a three-phase non-effective grounding power supply system needs to be improved in a fault period, so that the interphase short-circuit fault can be eliminated more conveniently.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a three-phase non-effective grounding power supply system convenient for fault treatment, which utilizes differential protection to carry out fault treatment aiming at a line with differential protection, can quickly locate a fault point interval for interphase faults outside a differential protection area and can automatically, quickly and accurately remove the faults.

In order to achieve the purpose, the utility model adopts the following technical scheme:

a three-phase non-effective grounding power supply system convenient for fault treatment comprises a power supply and a bus, wherein at least one outgoing line is arranged on the bus, a circuit breaker is arranged on the outgoing line, a plurality of controlled switches are arranged below the circuit breaker, the controlled switches can detect current information of each phase and can cut off a circuit according to the current information, and at least one section of differential protection area is arranged on at least one outgoing line;

a first switch is arranged on the outgoing line, the first switch can enable any one of two phases or three phases of the outgoing line to be in short circuit with the circuit breaker at the position of the circuit breaker, and the first switch is the controlled switch; a third switch is arranged at the lower port of the circuit breaker and can be used for connecting any one of the two phases or the three phases of the outgoing line with the ground; and a second switch is arranged on two or three phases of the system or on a system neutral point, the second switch is communicated with the ground through a variable resistance box, and the second switch can be used for connecting any one of the two or three phases of the system with the ground or connecting the system neutral point with the ground.

Preferably, the differential protection area has an electric energy inlet and a plurality of electric energy outlets, an inlet switch is installed on the electric energy inlet, an outlet current detection device is installed on each electric energy outlet, each outlet current detection device transmits a current value of the electric energy outlet to the inlet switch, the inlet switch calculates a difference value between the current value of the electric energy inlet and a sum of the current values of the electric energy outlets, and the inlet switch trips when the difference value exceeds a threshold value.

Preferably, the controlled switch is arranged outside the differential protection zone and at an electric energy outlet at the tail end of the differential protection zone.

Preferably, the first switch is capable of shorting any one of the three phases of the outgoing line to the circuit breaker at the circuit breaker.

Preferably, the current information is duration information of current or number information of current pulses, and when the controlled switch detects the current duration information, the duration of the current triggered to be cut off by the controlled switch at the downstream of the power supply is set to be shorter than the duration of the current triggered to be cut off by the controlled switch at the upstream of the power supply; when the controlled switch detects the number information of the current pulses, the number of the current pulses triggered and cut off by the controlled switch at the downstream of the power supply is set to be less than that triggered and cut off by the controlled switch at the upstream of the power supply.

Preferably, the second switch is a power electronic switch.

Preferably, the power electronic switch is an insulated gate bipolar transistor.

Preferably, each outgoing line is provided with at least two line fault processing modules for controlling the actions of the circuit breaker, the first switch, the third switch and the second switch, and is further provided with a fault management module for controlling each line fault processing module, and the fault management module is used for receiving a time signal of occurrence of each line fault and starting the line fault processing modules of each fault line according to time sequence.

Preferably, the variable resistor box comprises a driving circuit and a plurality of resistors with different resistance values, each resistor is connected with a resistor switch in series to form a series unit, all the series units are connected in parallel, and the driving circuit is used for controlling whether the resistor switches are closed or not.

Preferably, the resistor in one of the series units is a wire.

The utility model has the beneficial effects that: faults within the differential protection zone are handled quickly by the differential protection, while faults outside the differential protection zone are handled by the current pulses or current durations produced. Specifically, the inter-phase short-circuit fault or the incidental ground fault occurs outside the differential protection area, the circuit breaker is first cut off, then the first switch conducts a faulty phase at the circuit breaker, the third switch grounds the other faulty phase (if the inter-phase short-circuit incidental ground fault, the third switch may not be closed but directly utilizes the grounding point), then the second switch is grounded to form a fault detection loop and generate current (the cyclic grounding and disconnecting operation may generate a current pulse, and the direct grounding may generate a current with a certain duration), the current pulse or the current duration is detected by the controlled switch on the conducted faulty phase, and the controlled switch is automatically tripped after the trigger condition is reached, thereby eliminating the fault (because the number of current pulses triggered to be cut by the controlled switch downstream of the power supply may be set to be smaller than the number of current pulses triggered to be cut by the controlled switch upstream of the power supply, the controlled switches positioned below the interphase short-circuit fault point on the fault phase cannot enter a closed loop, and no current pulse flows through the controlled switches, so that the first controlled switch above the interphase short-circuit fault point is surely switched off first, and the interphase short-circuit fault is eliminated; the principle of the current duration is similar, the second switch generates current by grounding once, and then the controlled switch is used for detecting the current duration, and the current duration triggered and cut off by the controlled switch at the downstream of the power supply is set to be shorter than the current duration triggered and cut off by the controlled switch at the upstream of the power supply, so that the controlled switch at the nearest position above the fault point can be cut off to eliminate the fault). For the differential protection area, the first switch in the differential protection area is not cut off according to the current pulse or the current duration so as to fully utilize the differential protection, but for the switch at the electric energy outlet of the differential protection area, the first switch can be cut off according to the current pulse or the current duration so as to process the fault outside the electric energy outlet. For the condition that a plurality of lines have faults in the same time period, the utility model carries out unified processing by arranging the line fault management module.

Drawings

FIG. 1 is a schematic diagram of the power supply system of the present invention;

fig. 2 is a schematic diagram of a variable resistance box structure.

Detailed Description

The utility model will be further illustrated by the following specific embodiments in conjunction with the accompanying drawings:

the three-phase power supply system comprises a power supply, a bus, outgoing lines and loads, wherein a three-phase circuit breaker is arranged on the outgoing lines, a plurality of controlled switches are arranged below the three-phase circuit breaker, the controlled switches can detect current pulses on one phase, two phases or three phases of a detection line according to setting, can set switches for cutting off the three-phase line when the current pulse number of any phase reaches a preset value, and can also set current duration of one phase, two phases or three phases of the detection line according to setting, and can trip corresponding controlled switches according to different current durations of any phase. In a specific embodiment of the controlled switch, the controlled switch includes a control unit, a current detection unit and an execution unit, the current detection unit can respectively detect the pulse number or the duration of each phase current of the three-phase line, the control unit compares the current pulse number or the current duration detected by the current detection unit with a preset value, and can set the current pulse number of any phase to reach the preset value and send a signal to the execution unit to cut off the three-phase line. And aiming at the preset value of the current pulse number triggering cut-off, the preset value of the current pulse number of the controlled switch at the downstream of the power supply direction is smaller than the preset value at the upstream of the power supply direction, or the preset value of the set current duration of the controlled switch at the downstream of the power supply direction is shorter than the preset value of the current duration at the upstream of the power supply direction. The power source is upstream, i.e. relatively closer to the power source, and the power source is downstream, i.e. relatively further away from the power source, i.e. the power is emitted from the power source and is transported from upstream to downstream. Or, when viewed from the upstream and downstream of the power supply direction, the smaller the preset value of the pulse number or the shorter the preset value of the current duration for triggering and cutting off the controlled switch which is farther away from the power supply, the easier the trigger condition is reached first for cutting off. In practice, the circuit breakers arranged on each outgoing line are provided with a current detection device which can detect the number of current pulses or the current duration flowing through the circuit breakers, and can set a certain phase or a plurality of phases to cut off the line when a certain number of current pulses or current duration passes through the phase or the plurality of phases, so that the circuit breakers can be regarded as controlled switches.

As shown in fig. 1, the three-phase non-effective ground power supply system convenient for fault handling includes at least one section of differential protection area 100, as shown by a dashed line frame, the differential protection area 100 has an electric energy inlet and a plurality of electric energy outlets, switches are arranged at the electric energy inlet and the electric energy outlets, and the switch 102 at the outlet sends current information to the switch 101 at the inlet through a signal line, the switch 101 at the inlet compares whether the sum of the inlet current and each outlet current is equal, if the difference value is greater than a threshold value, it is determined that a short-circuit fault occurs in the area, and the inlet switch 101 trips to remove the fault, and the differential protection is implemented by the prior art. The controlled switches are arranged outside the differential protection area and at the electric energy outlets of the differential protection area, if all lines are the differential protection area, only the last switch of the electric energy outlets is arranged to be the controlled switch, and at the moment, the controlled switch only processes faults such as phase short circuit and the like between the controlled switch and a load (the section of the controlled switch is outside the differential protection area and cannot be protected through the differential, at the moment, the controlled switch can be set to cut off when 1 current pulse is detected or set to cut off when the time length of the detected current exceeds 0 second after the short circuit fault occurs, and specific reasons are shown in the following text). If the differential protection area and the non-differential protection area are arranged in a staggered mode, a controlled switch is arranged in the non-differential protection area.

In one embodiment, a first breaker 90 is arranged on each outgoing line of the three ABC phases and close to a bus, a first switch 1 is arranged at the first breaker 90, the first switch 1 comprises three switches KA1, KB1 and KC1 which are arranged on the three ABC phases, and the first switch 1 can short-circuit a certain phase at the first breaker 90 (for example, after the first breaker 90 cuts off the line, a switch KA1 in the first switch 1 is closed, namely, the phase A can be short-circuited so that the phase A bypasses the first breaker 90 to be switched on again), so that even if the first breaker is switched off, the short-circuited phase is still switched on and electrified. A plurality of circuit breakers are arranged below the first circuit breaker 90 (the circuit breakers below the first circuit breaker can be set as controlled switches, and the first circuit breaker can be set to have no function of the controlled switches and only realize on-off), and each circuit breaker can cut off a three-phase line according to the current pulse number of a certain phase. The third switch 3 is arranged at the lower port of the first breaker 90 of each outgoing line, and three switches KA3, KB3 and KC3 in the third switch 3 can respectively conduct the ABC three phases to the ground, so that any phase can be grounded. Meanwhile, a second switch 2 is also arranged on the bus, and three switches KA2, KB2 and KC2 in the second switch 2 can respectively ground and disconnect the three phases of the bus (the second switch can also be arranged at the neutral point of the system, and only one phase switch is needed at this time). If a simple phase-to-phase short circuit (such as a BC two-phase short circuit or a three-phase short circuit) occurs at a point F outside the differential protection zone, the first pair of circuit breakers 90 are tripped to cut off the three-phase line, then one failed phase (such as the B phase, the switch KB1 is closed) is conducted and electrified by closing one switch of the first switch 1, and then the other failed phase (i.e. the C phase, and the switch KC3 is closed) is conducted with the ground by using one switch of the third switch 3 at the lower port of the first pair of circuit breakers 90. Thus, the B phase of the line passes through the short-circuit point F to the C phase and then to the grounding point, and single-phase grounding is formed. Then, the phase A (the phase A is a charged phase) is circularly switched on and off with the ground at the upper port of the first breaker through one switch KA2 in the second switch, so that a current pulse is repeatedly generated (or the phase C is circularly grounded and disconnected by using a switch KC2, a closed loop can be formed and a current pulse is generated, or the phase C is grounded and disconnected at a neutral point, a current pulse can be formed), the current pulse flows through the fault phase B through the grounding point of the second switch, the grounding point of the third switch and the interphase short-circuit point F, when the current pulse number reaches the triggering condition of the controlled switch 91 which is nearest above the interphase short-circuit point F, the controlled switch 91 cuts off the line, so that the interphase short-circuit point F is excluded from the system (at this time, the triggering condition of the controlled switch further upstream is not reached yet, so the controlled switch further upstream is not cut off, and the controlled switch below the interphase short-circuit point on the B has no current pulse flowing therethrough, so there is no action). Then the switch KB1 on the first switch 1 is opened, the KC3 in the third switch 3 is grounded, the KA2 in the second switch is circularly grounded, and finally the first switch breaker 90 is closed to restore the line power supply.

In another embodiment of a three-phase non-active ground power supply system that facilitates fault handling, if an inter-phase short occurs at point F outside the differential protection zone and is incidental to ground at the short point, it is still possible to make an artificial ground point with the third switch and then generate a current pulse through the second switch. However, instead of using the third switch for grounding, it is also possible to use the grounding point of the fault generation directly: the first circuit breaker 90 is tripped to cut off the three-phase line, then the switch KB1 of the first switch is closed, the grounding point at the short-circuit point is directly utilized to produce single-phase grounding, then the phase a (or phase C) is circularly switched on and off with the ground at the upper port of the first circuit breaker through the second switch, so that current pulse is repeatedly generated, the current pulse flows through the fault phase B through the grounding point of the second switch and the grounding point F at the interphase short-circuit point, and when the current pulse number reaches the triggering condition of the nearest controlled switch 91 above the interphase short-circuit point, the controlled switch 91 cuts off the line, thereby removing the interphase short-circuit point F from the system. The switch KB1 of the first switch is then opened, stopping the second switch 2 from cyclically connecting the live phase to ground, and closing the first switch disconnector 90 to restore the line supply. In the above embodiment, the variable resistance box 8 is connected in series to the second switch, so as to avoid impact and damage to the system caused by excessive short circuit current between phases. In one embodiment, the variable resistor box 8 includes a driving circuit and a plurality of resistors 801 with different resistance values, each of the resistors 801 is connected in series with a resistor switch 802 to form a series unit, all the series units are connected in parallel, and the driving circuit is configured to receive an output of the short-circuit current value signal and output a signal for selecting a resistor, so as to drive the resistor switch to act, that is, to control whether the resistor switch is closed or not. In particular, the resistor in one of the series units is a wire 803, so that the value of the series resistor can be made zero, as shown in fig. 2.

In the above embodiments, the controlled switch trips when the trigger condition is reached, preventing the next current pulse from flowing, and thus avoiding tripping the further upstream controlled switch.

In the above embodiment, if the point F is located in the differential protection area, the sum of the current value of the power inlet and the current value of each power outlet of the differential protection area is not equal to each other due to an inter-phase short circuit or a ground fault, and the difference value exceeds the threshold, then the inlet switch 101 will trip at this time, so that the fault can be eliminated by using the differential protection. The first switch in the differential protection zone does not need to have all the functions of the controlled switch, and certainly, if the controlled switch is also arranged in the differential protection zone, when the differential protection fails to work, the fault can be eliminated through the controlled switch by utilizing a method for generating current pulses, and the current pulse can be used as a supplement of the differential protection.

In the above embodiment, the first circuit breaker 90 can also be used as a power inlet switch of a differential protection zone, and in this case, the first circuit breaker 90 also takes the trip function of the differential protection zone in addition to the aforementioned functions.

In the power supply system, when an interphase short circuit or a ground fault occurs in a differential protection area, the fault is removed through the differential protection, and the power supply system can be realized by adopting the prior art. And when the phase-to-phase short circuit or the ground fault occurs outside the differential protection area, conducting the ground through a second switch to generate current, and utilizing the controlled switch to remove the fault according to the detected current information.

In the above two embodiments of the power supply system, it may also be configured that the controlled switches do not detect the number of current pulses, but detect the current duration, at this time, the current duration triggered to turn off by the controlled switch downstream of the power supply is set to be shorter than the current duration triggered to turn off by the controlled switch upstream of the power supply, and the controlled switches are tripped in time, so that the current duration that does not pass through can trigger the previous controlled switch to trip, otherwise, the power outage area is enlarged. At the moment, the second switch is only needed to be grounded once, and the second switch is stopped from being grounded after the controlled switch is tripped. I.e. the second switch can be tripped to ground when it detects no current.

In the above embodiment, if the first switch is a two-phase single-phase switch and the third switch is a two-phase single-phase switch, the first switch and the third switch can be combined to conduct a fault phase and ground the other fault phase, and at this time, one of the first switch and the third switch needs to be in a different phase.

In one embodiment, power electronic switches, such as insulated gate bipolar transistors, are used to achieve short-time cyclic grounding, disconnection (for the number of pulses of the sense current), or one-time grounding and then disconnection (for the duration of the sense current). Presently, igbts are capable of high power on and off and have microsecond order response, producing short circuit current pulses several milliseconds long.

In the specific implementation of the above scheme, a line fault processing module may be provided for each outgoing line, and is used to control the actions of the circuit breaker, the first switch, the third switch and the second switch. And a unified fault management module can be arranged for all outgoing lines and controls each line fault processing module. When a plurality of outgoing lines have phase-to-phase short circuit or ground fault in the same time period, if the phase-to-phase short circuit or the ground fault occurs in the differential protection area, the faults are respectively processed through differential protection, and if the phase-to-phase short circuit or the ground fault occurs outside the differential protection area, the fault management module receives a time signal of each line fault and starts the line fault processing modules of each fault line according to time sequence.

The same time interval is the time interval when the fault of the outgoing line which firstly generates the interphase short circuit or the ground fault is not removed, and the other outgoing lines generate the interphase short circuit or the ground fault. If so, the numbering order of the outgoing lines.

If a single-phase earth fault occurs, if the fault occurs in a differential protection area, the sum of an inlet current value and an outlet current value is unequal due to the existence of single-phase earth, so that the inlet switch is tripped, but the grounding current is very small at the moment and is limited to the detection limit of precision, and the inlet switch cannot be tripped at the moment if the difference value of the inlet current and the outlet current does not exceed the threshold value. Therefore, for a single-phase earth fault inside the differential protection zone which cannot be processed, and for a single-phase earth fault outside the differential protection zone, the second switch can be circularly grounded or grounded once, so that a fault detection loop is formed between the ground point and a fault phase, the bus and the power supply, and the second switch and the earth, and a current pulse or a current with a duration is generated, for the earth fault inside the differential protection zone, the artificial current can cause differential protection tripping, for the earth fault outside the differential protection zone, the controlled switch can detect the current pulse or the duration, and trip the controlled switch above the fault point according to a preset tripping condition, so that the fault is eliminated. In addition, when the second switch is used to generate the current pulse or the current duration, the circuit breaker may be tripped first, then the fault phase is turned on by the first switch (at this time, the first switch is required to be able to turn on any one of the three phases), and then the second switch is used to generate the current pulse or the current duration. The purpose of doing so is closer with the action logic of handling the interphase fault to make interphase fault and single-phase earth fault share a set of logic as far as possible, promote systematic nature and the unity of fault handling.

The above embodiments are only a few illustrations of the inventive concept and implementation, not limitations thereof, and the technical solutions without substantial changes are still within the scope of protection under the inventive concept.

Claims (10)

1. A three-phase non-effective grounding power supply system convenient for fault treatment comprises a power supply and a bus, wherein at least one outgoing line is arranged on the bus, the three-phase non-effective grounding power supply system is characterized in that a circuit breaker is arranged on the outgoing line, a plurality of controlled switches are arranged below the circuit breaker, the controlled switches can detect current information of each phase and can cut off a circuit according to the current information, and at least one section of differential protection area is arranged on at least one outgoing line;

a first switch is arranged on the outgoing line, the first switch can enable any one of two phases or three phases of the outgoing line to be in short circuit with the circuit breaker at the position of the circuit breaker, and the first switch is the controlled switch; a third switch is arranged at the lower port of the circuit breaker and can be used for connecting any one of the two phases or the three phases of the outgoing line with the ground; and a second switch is arranged on two or three phases of the system or on a system neutral point, the second switch is communicated with the ground through a variable resistance box, and the second switch can be used for connecting any one of the two or three phases of the system with the ground or connecting the system neutral point with the ground.

2. The three-phase non-virtual ground power supply system facilitating fault handling of claim 1, wherein said differential protection zone has a power inlet and a plurality of power outlets, an inlet switch is mounted on the power inlet, an outlet current detection device is mounted on each of said power outlets, each of said outlet current detection devices transmits a current value of the power outlet to said inlet switch, the inlet switch calculates a difference between the current value of the power inlet minus a sum of current values of the power outlets, and said inlet switch trips when said difference exceeds a threshold value.

3. The three-phase inactive ground power supply system facilitating fault handling as set forth in claim 1, wherein said controlled switch is disposed outside said differential protection zone and at a power outlet at an end of said differential protection zone.

4. The three-phase inactive ground power supply system facilitating fault handling of claim 1, wherein said first switch is capable of shorting any of said three phases of said outgoing line to a circuit breaker at said circuit breaker.

5. The three-phase non-active ground power supply system facilitating fault handling according to any one of claims 1 to 4, wherein the current information is duration information of current or number information of current pulses, and when the controlled switch detects the current duration information, the duration of current triggered to be cut by the controlled switch downstream of the power supply is set shorter than the duration of current triggered to be cut by the controlled switch upstream of the power supply; when the controlled switch detects the number information of the current pulses, the number of the current pulses triggered and cut off by the controlled switch at the downstream of the power supply is set to be less than that triggered and cut off by the controlled switch at the upstream of the power supply.

6. The three-phase inactive ground power supply system facilitating fault handling as set forth in claim 1, wherein said second switch is a power electronic switch.

7. The three-phase inactive ground power supply system facilitating fault handling according to claim 6, wherein said power electronic switches are insulated gate bipolar transistors.

8. The three-phase inactive ground power supply system for facilitating fault handling of claim 1, wherein there are at least two said outgoing lines, each outgoing line being provided with a line fault handling module for controlling the actions of said circuit breaker, first switch, third switch and second switch, and a fault management module for controlling each of said line fault handling modules, the fault management module being adapted to receive a time signal of occurrence of each line fault and to activate the line fault handling modules of each faulty line in chronological order.

9. The three-phase inactive ground power supply system for facilitating fault handling as claimed in claim 1, wherein said variable resistor box includes a driving circuit and a plurality of resistors having different resistance values, each of said resistors being connected in series with a resistor switch to form a series unit, all of said series units being connected in parallel, said driving circuit being adapted to control whether said resistor switches are closed.

10. The three-phase inactive ground power supply system for facilitating fault handling as claimed in claim 9, wherein said resistor in one of said series units is a wire.

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