CN113949044B - Three-phase non-effective grounding power supply system - Google Patents
Three-phase non-effective grounding power supply system Download PDFInfo
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- CN113949044B CN113949044B CN202110141550.5A CN202110141550A CN113949044B CN 113949044 B CN113949044 B CN 113949044B CN 202110141550 A CN202110141550 A CN 202110141550A CN 113949044 B CN113949044 B CN 113949044B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- 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
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Abstract
The invention discloses a three-phase non-effective grounding power supply system, wherein 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 cut off a line according to the current information, and at least one section of differential protection area is arranged on the outgoing line; the first switch is arranged on the outgoing line, the third switch is arranged at the lower opening of the circuit breaker, the second switch is arranged on the bus or the neutral point of the system, the second switch is communicated with the ground through the 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 neutral point of the system with the ground. The system aims at the circuit with differential protection, can fully utilize the rapid advantage of the differential protection, and can also rapidly locate the inter-phase short-circuit fault point interval in the area without the differential protection and automatically, rapidly and accurately cut off faults.
Description
Technical Field
The invention relates to the field of power supply system fault processing, in particular to a three-phase non-effective grounding power supply system.
Background
When interphase short circuit occurs on the three-phase non-effective grounding power supply system, a differential protection mode can be adopted to rapidly cut off faults. The differential protection is to utilize the current comparison between the electric energy inlet switch and the electric energy outlet switches, and trip when the difference value of the sum of the inlet current and the outlet current is larger than the threshold value, so as to cut off the faults in the differential protection area. But differential protection cannot handle faults outside the differential protection zone. For lines where no differential protection zone is provided, the following approach can be generally taken to handle the fault: 1. the reclosing mode is adopted: the first breaker on the line is first cut and then closed again, and if there is a momentary phase-to-phase short circuit and this is eliminated after the first breaker has been closed, normal power supply is continued. If the phase-to-phase short fault still exists after the first breaker is closed, the first breaker is disconnected and the maintenance is waited. 2. The method adopts a time level difference matching method: the method can isolate a fault area, but for faults with fault points close to the power supply, the short-circuit current tolerance time is long, and the impact on a power grid is large. 3. And if the interphase short circuit occurs between the penultimate breaker and the last breaker, the faults can be removed, and the like, the breakers are sequentially cut off upwards until the faults are removed. However, during this operation, the circuit breaker, which is not cut off, is continuously subjected to a large short-circuit current surge, and if it is too long, damage to the line is caused. If the duration of the inter-phase short circuit cannot exceed 300 ms and the tripping time of the circuit breaker is 100ms, three circuit breakers are not suitable for the common line, otherwise, the method may cause the line to impact more than 300 ms.
For better fault handling of the line provided with the differential protection area, the structure of the three-phase non-effective grounding power supply system needs to be improved in the fault period so that the inter-phase short circuit fault can be removed more conveniently.
Disclosure of Invention
The invention aims to provide a three-phase non-effective grounding power supply system, which is used for carrying out fault treatment on a circuit with differential protection by utilizing the differential protection, and can also quickly locate fault point intervals and automatically, quickly and accurately cut off faults for inter-phase faults outside a differential protection area.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the three-phase non-effective grounding power supply system 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 cut off a line 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 the outgoing line, the first switch can short-circuit a breaker at the breaker by any one of two phases or three phases of the outgoing line, and the first switch is the controlled switch; a third switch is arranged at the lower opening of the circuit breaker, and the third switch can be used for connecting any one of two phases or three phases of the outgoing line with the ground; a second switch is arranged on two phases or three phases of the system or on a neutral point of the system, 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 phases or three phases of the system with the ground or connecting the neutral point of the system with the ground;
when a simple inter-phase short circuit or an inter-phase short circuit occurs while a ground fault is attached, if the fault occurs within the differential protection zone, the fault is removed by differential protection, and if the fault occurs outside the differential protection zone, a fault detection loop is manufactured using the circuit breaker, a first switch, a third switch, or an inter-phase short circuit attached ground point and a second switch and generates a current, which is detected by the controlled switch and tripped according to a preset trip condition to remove the fault.
Preferably, the differential protection area is provided with an electric energy inlet and a plurality of electric energy outlets, an inlet switch is arranged on the electric energy inlet, an outlet current detection device is arranged on each electric energy outlet, each outlet current detection device transmits the current value of the electric energy outlet to the inlet switch, the inlet switch calculates the difference value of the current value of the electric energy inlet minus the sum of the current values of the electric energy outlets, and when the difference value exceeds a threshold value, the inlet switch trips.
Preferably, the controlled switch is arranged outside the differential protection area and at an electric energy outlet at the tail end of the differential protection area.
Preferably, when a simple interphase short circuit occurs outside the differential protection area or a ground fault is attached at the same time, the circuit breaker trips, the first switch conducts one fault phase, the third switch grounds the other fault phase, the second switch turns on the live phase except for the one fault phase to the ground to generate a current, and the controlled switch detects the current and trips according to a preset trip condition to cut off the fault.
Preferably, when a single-phase earth fault occurs inside or outside the differential protection area or when an inter-phase short circuit occurs outside the differential protection area while an earth fault is attached, the circuit breaker trips, the first switch conducts a fault phase, the fault phase is conducted to the earth by using the earth point of the fault, the second switch switches on a live phase or a system neutral point except the fault phase to the earth to generate a current, the single-phase earth fault or the inter-phase short circuit outside the differential protection area while the earth fault is attached, the controlled switch detects the current and trips according to a preset trip condition to cut off the fault, and the single-phase earth fault inside the differential protection area is removed by differential protection. This is because, when a single-phase ground occurs in the differential protection area, since a ground current occurs, the difference between the sum of the differential protection area inlet current value and each outlet current value may exceed a threshold value, thereby causing the inlet switch to trip and cut off the fault. However, the ground current is sometimes small, and the difference may not exceed the threshold value, so that the trip cannot be performed. At this time, the current pulse or the current having a certain length of time is generated by the above method, the above difference is increased to exceed the threshold value and trip is caused. And removing faults outside the differential protection area through the controlled switching action.
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 and 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 and 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 smaller than the number of the current pulses 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, at least two outgoing lines are provided, each outgoing line is provided with a line fault processing module for controlling the actions of the circuit breaker, the first switch, the third switch and the second switch, and a fault management module is further provided, and is used for controlling each line fault processing module, when the plurality of outgoing lines generate interphase short-circuits or interphase short-circuits and simultaneously attach a ground fault in the same time period, if the interphase short-circuits or the interphase short-circuits and simultaneously attach the ground fault in the differential protection area, the fault processing modules respectively process the faults through differential protection, and if the interphase short-circuits or the interphase short-circuits and the simultaneously attach the ground fault outside the differential protection area, the fault management module receives a time signal of each line fault occurrence and starts the line fault processing modules of each fault line according to time sequence.
Preferably, the time interval from the tripping of the circuit breaker to the grounding of the second switch for generating the current is set according to the reclosing time of each outgoing line.
Preferably, the variable resistance box comprises a driving circuit and a plurality of resistors with different resistance values, each resistor is connected in series with a resistance switch to form a series unit, all the series units are connected in parallel, and the driving circuit is used for controlling whether the resistance switch is closed or not.
Preferably, the resistor in one of the series units is a wire.
The invention has the beneficial effects that: faults within the differential protection zone are handled quickly by differential protection, while faults outside the differential protection zone are handled by manufactured current pulses or current durations. Specifically, the circuit breaker is firstly disconnected when an interphase short-circuit fault or an additional grounding fault occurs outside the differential protection area, then the first switch conducts a fault phase at the circuit breaker, the third switch grounds the other fault phase (if the interphase short-circuit is attached with the grounding fault, the grounding point can be directly utilized without closing the third switch), then the second switch is grounded to form a fault detection loop and generate current (the circulation grounding and the disconnection operation can generate current pulses, and a certain time period can be generated when the direct grounding is carried out), the controlled switch on the conducted fault phase detects the current pulses or the current time period, and automatically breaks the controlled switch after the trigger condition is reached, so that the fault is eliminated (because the number of the current pulses triggered and disconnected by the controlled switch on the downstream of the power supply is smaller than the number of the current pulses triggered and disconnected by the controlled switch on the upstream of the power supply, the controlled switch on the fault phase cannot enter the closed loop, no current pulse flows, the first controlled switch above the interphase short-circuit point is firstly disconnected, so that the interphase short-circuit fault is generated, the phase current is disconnected, the current is generated, the controlled switch is triggered by the controlled switch on the phase, the second switch is shorter than the phase, the current is triggered by the controlled switch, the controlled switch on the upstream of the downstream of the power supply has a trigger condition, the controlled switch is triggered by the controlled switch, the controlled switch is disconnected when the controlled switch is disconnected, the controlled switch has a trigger time period is shorter than the phase, and the controlled switch is generated, and the phase has a controlled switch is disconnected, which is connected to the phase has a fault. For the differential protection area, the head 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 head switch can be cut off according to the current pulse or the current duration so as to treat faults outside the electric energy outlet. For the situation that a plurality of lines have faults in the same period, the invention performs unified processing by arranging the line fault management module.
Drawings
FIG. 1 is a schematic diagram of a power supply system of the present invention;
fig. 2 is a schematic diagram of the structure of the varistor case.
Detailed Description
The invention is further illustrated by the following examples, taken 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 breaker is arranged on the outgoing lines, a plurality of controlled switches are arranged below the three-phase breaker, the controlled switches can be used for setting current pulses on one phase, two phases or three phases on the detection line, and can be used for cutting off the three-phase line when the number of the current pulses passing through any one phase reaches a preset value, or can be used for setting the current duration of one phase, two phases or three phases on the detection line, and tripping the corresponding controlled switches according to the difference of the current durations of any one phase. In a specific embodiment related to the controlled switch, the controlled switch includes a control unit, a current detection unit and an execution unit, where the current detection unit can detect the pulse number or the duration of each phase of 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 a signal to make the execution unit cut off the three-phase line when the current pulse number of any phase reaches the preset value. For a preset value of the number of current pulses triggering the switching off, the preset value of the number of current pulses of the controlled switch downstream in the power supply direction is smaller than the preset value upstream in the power supply direction, or the preset value of the set current duration of the controlled switch downstream in the power supply direction is smaller than the preset value of the current duration upstream in the power supply direction. The upstream side of the power supply, i.e. relatively closer to the power supply, and the downstream side of the power supply, i.e. relatively further away from the power supply, i.e. electrical energy is emitted from the power supply and transmitted from the upstream side to the downstream side. Or, as seen 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 of the controlled switch trigger switch which is farther from the power supply, the easier the trigger condition is reached so as to switch off. In practice, the circuit breaker is arranged on each outgoing line, the current detection device is arranged to detect the number of current pulses or the current duration of the current flowing through the circuit breaker, and one phase or a plurality of phases can be arranged to cut off the line when passing through a certain number of current pulses or the current duration, so the circuit breaker can be regarded as a controlled switch.
As shown in fig. 1, the three-phase non-effective ground power supply system includes at least one differential protection area 100, as shown by a dotted 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 outlets, the switch 102 of the outlet sends current information to the switch 101 of the inlet through a signal line, the switch 101 of the inlet compares whether the sum of the inlet current and each outlet current is equal, if the difference is greater than a threshold value, a short circuit fault occurs in the area, the switch 101 of the inlet trips to cut off the fault, and the differential protection is realized through the prior art. The controlled switch is arranged outside the differential protection area and at the electric energy outlet of the differential protection area, if all lines are the differential protection area, only the last switch of the electric energy outlet is arranged as the controlled switch, and at the moment, the controlled switch only processes faults such as interphase short circuit and the like between the controlled switch and a load (the area is outside the differential protection area and cannot be protected by differential, at the moment, the controlled switch can be set to detect 1 current pulse to be cut off or set to detect the current to be cut off after the occurrence of the short circuit fault for more than 0 seconds, and the specific reason is described below). If the differential protection area and the non-differential protection area are arranged in a staggered way, a controlled switch is arranged in the non-differential protection area.
In one embodiment, a first breaker 90 is disposed on each outgoing line of ABC three phases near the bus, a first switch 1 is mounted on the first breaker 90, the first switch 1 includes three switches KA1, KB1 and KC1 mounted on ABC three phases, the first switch 1 is capable of shorting a phase at the first breaker 90 (e.g. after the first breaker 90 breaks the line, the switch KA1 in the first switch 1 is closed to short the a phase to make the a phase bypass the first breaker 90 and be turned back on), so that even if the first breaker is broken, the shorted phase is still electrically conductive. A plurality of circuit breakers are provided below the first circuit breaker 90 (the circuit breakers below the first circuit breaker may be controlled switches, and the first circuit breaker may be provided without a function of controlled switches, and only simply realize on-off), and each circuit breaker may cut off a three-phase line according to the current pulse number of a certain phase. A third switch 3 is installed at the lower port of the first circuit breaker 90 of each outgoing line, and three switches KA3, KB3 and KC3 in the third switch 3 can respectively conduct ABC three phases to the ground, so that any one 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 enable three phases of the bus to be grounded and disconnected (the second switch can also be arranged at a neutral point of the system, and only one phase of switch is needed at the moment). If a simple interphase short circuit (such as BC two-phase short circuit or three-phase short circuit) occurs at the point F outside the differential protection area, the first breaker 90 is first tripped to cut off the three-phase line, then one fault phase (such as B phase, when the switch KB1 is closed) is conducted and electrified by closing one switch of the first switch 1, and then the other fault phase (i.e. C phase, when the switch KC3 is closed) is conducted with the ground at the lower port of the first breaker 90 by using one switch of the third switch 3. Thus, the phase B of the line passes through the short-circuit points F to C and then to the grounding point, and single-phase grounding is formed. The phase a (in which the phase a is a live phase) is then cycled on and off from the ground at the first switch upper port by one of the second switches KA2, which repeatedly generates a current pulse (or the phase C is cycled on and off by the switch KC2, or a closed loop may be formed and a current pulse may be generated, or the phase C is grounded or off at the neutral point, or a current pulse may be formed) which flows through the phase B of the fault phase via the ground point of the second switch, the ground point of the third switch and the phase-to-phase short point F, and when the number of current pulses reaches the trigger condition of the nearest controlled switch 91 above the phase-to-phase short point F, the controlled switch 91 cuts off the line, thereby excluding the phase-to-phase short point F from the system (in which the trigger condition of the more upstream controlled switch has not been reached yet, so the more upstream controlled switch will not be cut off, and the controlled switch below the phase-to-phase short point B will not operate because no current pulse flows). Then switch KB1 on the first switch 1 is opened, KC3 in the third switch 3 is stopped to be grounded, KA2 in the second switch is stopped to be circularly grounded, and finally the first breaker 90 is closed to restore line power supply.
In another embodiment regarding a three-phase non-active ground power system, if an inter-phase short circuit occurs at point F outside the differential protection area and is accompanied by a short-circuit point ground, an artificial ground point may still be made with the third switch and then a current pulse is generated through the second switch. However, instead of the third switch being grounded, the ground point generated by the fault may be directly used: the first breaker 90 is first tripped to cut off the three-phase line, then the switch KB1 of the first switch is closed, a single phase ground is manufactured directly by using the ground point at the short-circuit point, then the a phase (also the C phase) is circularly connected and disconnected with the ground at the upper port of the first breaker by the second switch, so that current pulses are repeatedly generated, the current pulses flow through the phase B phase of the fault via the ground point of the second switch and the ground point F at the phase-to-phase short-circuit point, and when the number of current pulses reaches the trigger condition of the nearest controlled switch 91 above the phase-to-phase short-circuit point, the controlled switch 91 cuts off the line, thereby excluding the phase-to-phase short-circuit point F from the system. The switch KB1 of the first switch is then opened, the second switch 2 is stopped to circularly ground the live phase, and the first breaker 90 is closed to restore line power. In the above embodiment, the variable resistance box 8 is connected in series to the second switch, so as to avoid the impact and damage to the system caused by excessive interphase short-circuit current. In one embodiment, the variable resistor box 8 comprises a driving circuit and a plurality of resistors 801 with different resistance values, each resistor 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 used for controlling 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 resistance of the series resistor can be zero, as shown in fig. 2.
In the above embodiments, the controlled switch is timely when the trigger condition is reached and the next current pulse is avoided from flowing, thereby avoiding tripping the controlled switch further upstream.
In the above embodiment, if the point F is located in the differential protection area, the sum of the current values of the power inlets and the current values of the power outlets of the differential protection area is unequal due to the inter-phase short circuit or the ground fault, and the difference exceeds the threshold value, the inlet switch 101 trips at this time, so that the differential protection can be utilized to remove the fault. The switch of the head switch in the differential protection area does not need to have all the functions of the controlled switch, and of course, if the controlled switch is also arranged in the differential protection area, when the differential protection is wrong and can not work, the controlled switch can be used for removing faults by a method of generating current pulses, and the method can be used as the supplement of the differential protection.
In the above embodiment, the first breaker 90 may also be used as an electric energy inlet switch of a differential protection zone, and the first breaker 90 also performs the tripping function of the differential protection zone in addition to the above-mentioned functions.
In the power supply system, when inter-phase short circuit or ground fault occurs in the differential protection area, the fault is removed through differential protection, and the power supply system can be realized by adopting the prior art. When an interphase short circuit or a ground fault occurs outside the differential protection area, the second switch is conducted to the ground to generate current, and the controlled switch is utilized to cut off the fault according to the detected current information.
In the embodiments of the two power supply systems, the controlled switch may not detect the number of current pulses, but detect the current duration, at this time, the current duration of triggering and cutting off of the controlled switch downstream of the power supply is set to be shorter than the current duration of triggering and cutting off of the controlled switch upstream of the power supply, and the controlled switch is tripped in time, so that the duration of the current which cannot pass through the controlled switch can trigger the last controlled switch to trip, otherwise, the power failure area is enlarged. At this time, only the second switch is required to be grounded once, and the second switch is stopped to be grounded after the controlled switch is tripped. I.e. the second switch can trip to ground when no current is detected.
In the above embodiment, if the first switch is a two-phase single-phase switch, the third switch is a two-phase single-phase switch, and one fault phase can be conducted and the other fault phase can be grounded through combination, at this time, one single-phase switch of the first switch and the third switch is located in different phases.
In one embodiment, a power electronic switch, such as an insulated gate bipolar transistor, is used to achieve short-time cyclical grounding, disconnection (for the number of sense current pulses), or one-time grounding and disconnection (for the duration of the sense current). The current insulated gate bipolar transistor can bear high-power on and off, is microsecond-level response and can produce short-circuit current pulses with a duration of a few milliseconds.
In a specific implementation of the above scheme, a line fault handling module may be provided for each outgoing line, for controlling 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 the fault management module controls each line fault processing module. When the inter-phase short circuit or the grounding faults occur in the same time period, if the inter-phase short circuit or the grounding faults occur in the differential protection area, the faults are processed through the differential protection, and if the faults occur outside the differential protection area, the fault management module receives the time signals of each line fault occurrence and starts the line fault processing module of each fault line according to the time sequence.
The same time period is the time period when the phase-to-phase short circuit or the ground fault occurs when the fault is not cut off, and the other outgoing lines have the phase-to-phase short circuit or the ground fault. If simultaneous, the number order of the outgoing lines.
If a single-phase earth fault occurs, if the fault occurs in the differential protection area, the sum of the inlet current value and the outlet current value is unequal due to the existence of single-phase earth, so that the inlet switch is tripped, but the earth current is very small and limited by the detection limit of precision, and the difference value between the inlet current and the outlet current is not more than a threshold value, so that the inlet switch is not tripped. Thus, for single-phase ground faults within the differential protection zone that are not addressed, and for single-phase ground faults outside the differential protection zone, the circuit breaker may be tripped, then the first switch turns on a faulty phase, then turns on a faulty phase to ground with the ground point of the fault, and then the second switch turns on the live phase or system neutral point other than the faulty phase to ground to generate current. For the ground fault in the differential protection area, the artificial current can cause the differential protection trip, and for the ground fault outside the differential protection area, the controlled switch can detect the current pulse or the duration and trip the controlled switch above the fault point according to the preset trip condition, thereby eliminating the fault.
The above embodiments are only a few descriptions of the inventive concept and implementation, and are not limited thereto, and the technical solutions without substantial transformation remain within the scope of protection under the inventive concept.
Claims (13)
1. The three-phase non-effective grounding power supply system comprises a power supply and a bus, wherein at least one outgoing line is arranged on the bus, and 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 cut off a line 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 short-circuit a breaker at the breaker by any one of two phases or three phases of the outgoing line, and the first switch is the controlled switch; a third switch is arranged at the lower opening of the circuit breaker, and the third switch can be used for connecting any one of two phases or three phases of the outgoing line with the ground; a second switch is arranged on two phases or three phases of the system or on a neutral point of the system, 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 phases or three phases of the system with the ground or connecting the neutral point of the system with the ground;
when a simple inter-phase short circuit occurs or an inter-phase short circuit is simultaneously attached with a ground fault, if the fault occurs in the differential protection zone, the fault is removed by differential protection, if the fault occurs outside the differential protection zone, a fault detection circuit is manufactured by using the circuit breaker, the first switch, the third switch and the second switch and generates a current, or a fault detection circuit is manufactured by using the circuit breaker, the first switch, the inter-phase short circuit attached with a ground point and the second switch and generates a current, and the current is detected by the controlled switch and tripped according to a preset trip condition to remove the fault.
2. The three-phase non-active ground power supply system of claim 1, wherein the differential protection zone has an electrical energy inlet and a plurality of electrical energy outlets, an inlet switch is mounted on the electrical energy inlet, an outlet current detection device is mounted on each of the electrical energy outlets, each of the outlet current detection devices communicates the current value of the electrical energy outlet to the inlet switch, the inlet switch calculates the difference of the current value of the electrical energy inlet minus the sum of the current values of each of the electrical energy outlets, and the inlet switch trips when the difference exceeds a threshold.
3. The three-phase, non-active ground power system of claim 1, wherein the controlled switch is disposed outside the differential protection zone and at an electrical energy outlet at an end of the differential protection zone.
4. The three-phase non-active ground power supply system according to claim 1, wherein when a simple phase-to-phase short circuit or a phase-to-phase short circuit occurs outside the differential protection area while a ground fault is attached, the circuit breaker trips, the first switch turns on one fault phase, the third switch grounds the other fault phase, the second switch turns on a live phase or a system neutral point other than the one fault phase with the ground to generate a current, and the current is detected by the controlled switch and tripped according to a preset trip condition to cut off the fault.
5. The three-phase non-active ground power supply system according to claim 1, wherein when a single-phase ground fault occurs inside or outside the differential protection zone or an inter-phase short circuit occurs outside the differential protection zone while a ground fault is attached, the circuit breaker trips, the first switch conducts a fault phase, the fault phase is conducted to the ground by the ground point of the fault, the second switch turns on a live phase or a system neutral point other than the fault phase to the ground to generate a current, the single-phase ground fault or the inter-phase short circuit outside the differential protection zone while the ground fault is attached, the controlled switch detects the current and trips to cut off the fault according to a preset trip condition, and the single-phase ground fault inside the differential protection zone is removed by differential protection.
6. The three-phase non-effective ground power supply system according to any one of claims 1 to 5, wherein the current information is duration information of a current or number information of current pulses, and when the controlled switch detects the current duration information, the duration of a current that the controlled switch downstream of the power supply triggers to cut off is set to be shorter than the duration of a current that the controlled switch upstream of the power supply triggers to cut off; 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 smaller than the number of the current pulses triggered and cut off by the controlled switch at the upstream of the power supply.
7. The three-phase, non-active ground power system of claim 1, wherein the second switch is a power electronic switch.
8. The three-phase, non-active ground power system of claim 7, wherein the power electronic switch is an insulated gate bipolar transistor.
9. The three-phase non-effective ground-connection power supply system according to claim 1, wherein at least two outgoing lines are provided, each outgoing line is provided with a line fault handling module for controlling actions of the circuit breaker, the first switch, the third switch and the second switch, and a fault management module is further provided for controlling each line fault handling module, when a plurality of outgoing lines are in inter-phase short circuit or inter-phase short circuit and simultaneously attached with a ground fault in the same period, if the inter-phase short circuit or the inter-phase short circuit and the simultaneously attached with the ground fault occur in the differential protection area, the fault handling modules respectively handle the faults through differential protection, and if the fault handling modules are out of the differential protection area, the fault management module receives a time signal of occurrence of each line fault and starts the line fault handling modules of each fault line according to time sequence.
10. The three-phase non-effective ground-up power supply system according to claim 9, wherein the same period is a period in which phase-to-phase short-circuits or phase-to-phase short-circuits occur first while an outgoing line with a ground fault is attached, and when the fault has not been cut off, other outgoing lines are also phase-to-phase short-circuits or phase-to-phase short-circuits occur while the ground fault is attached.
11. The three-phase non-active ground power supply system of claim 4 or 5, wherein the time interval from the tripping of the circuit breaker to the grounding of the second switch to the generation of the current is set according to the reclosing time of each outgoing line.
12. The three-phase non-active ground power supply system of claim 1, wherein the variable resistance box comprises a driving circuit and a plurality of resistors with different resistance values, each resistor is connected in series with a resistor switch to form a series unit, all series units are connected in parallel, and the driving circuit is used for controlling whether the resistor switch is closed or not.
13. The three-phase non-active ground power system of claim 12, wherein the resistor in one of the series units is a wire.
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