A power supply system convenient for handling interphase short circuit

Abstract

The present invention discloses a power supply system that facilitates handling interphase short circuits. The system includes a power supply and a three-phase line. The three-phase line is provided with a plurality of sectionalizing switches, which divide the three-phase line into a plurality of protection zones. Within the protection zones, a plurality of segmenting switches are provided. The lower ports of the segmenting switches are connected to the earth or a common conductor via a grounding switch. The busbar or system neutral point of the three-phase line is connected to the earth or the common conductor via a signal generating switch. The segmenting switches are capable of detecting current signals and tripping according to preset current conditions. The segmenting switches are also capable of detecting voltage signals and tripping according to preset voltage conditions. The system can disconnect the segmenting switches closest to either side of the interphase short circuit fault point, thereby eliminating the short circuit fault and allowing the system to self-heal. The system is easy to operate, requires relatively little hardware, and is relatively low in cost.

Description

Technical Field

[0001] The present invention relates to the field of power system protection, and in particular to a power supply system that is convenient for handling interphase short circuits. Background Art

[0002] Regarding the handling of interphase short circuits in three-phase power systems, the common practices are: 1. Use the reclosing method: first cut off the first circuit breaker on the line and then close the first circuit breaker. If it is a transient interphase short circuit and it is eliminated after closing the first circuit breaker, the power supply will continue normally. If the interphase short circuit fault still exists after closing the first circuit breaker, cut off the first circuit breaker and wait for maintenance. 2. Use the time differential coordination method: that is, the circuit breakers on the same line are set to different overcurrent trip times according to the distance from the power source. The closer to the power source, the longer the trip time. The general setting differential is 100ms. This time is determined by the mechanical action time of the switch and the time consumed by the algorithm. This method can isolate the fault area, but for faults where the fault point is close to the power source, the power supply system can withstand the short-circuit current for a long time, which has a great impact on the power grid. 3. Trip the first circuit breaker due to overcurrent, then trip the last load switch due to no current (while all other load switches remain closed). Then reclose the first circuit breaker. If the fault occurs below the last load switch, the fault can be eliminated. Otherwise, if the fault current still flows after reclosing the first circuit breaker, the first circuit breaker will trip again due to overcurrent, then the second-to-last load switch will trip due to no current. Then reclose the first circuit breaker again. If the phase-to-phase short circuit occurs between the second-to-last and last load switches, the fault can be eliminated. Repeat this process, disconnecting load switches in ascending order while no current flows until the fault is eliminated. However, during this operation, the power supply system is repeatedly subjected to large short-circuit current surges. Excessive occurrences can damage the line and prolong troubleshooting. 4. Equip all circuit breakers with fault current tripping capability. When a fault occurs, set all circuit breakers to trip due to overcurrent, then close them starting with the first circuit breaker. If there is overcurrent, the circuit breaker will trip, eliminating the fault. If the first circuit breaker closes successfully without overcurrent, it will be locked for a period of time, tripping due to overcurrent. During this time, the second circuit breaker is closed. Since the first circuit breaker has already been locked due to overcurrent, the second circuit breaker will trip due to overcurrent, and the fault will be eliminated. If there is no overcurrent, the next circuit breaker is closed, and so on. This solution requires each circuit breaker to be able to interrupt high currents, which places high demands on the circuit breaker and increases manufacturing costs. It also has complex logic and a relatively long self-healing time. Therefore, existing methods for handling phase-to-phase short circuits have the disadvantages of long fault processing time, high system impact, and high requirements on the switch's ability to interrupt high currents.

[0003] Invention patent application 202011453632.5 and invention patent application 202011453631.0 provide two methods for handling phase-to-phase short circuits. When a phase-to-phase short circuit occurs, a detection circuit is artificially constructed that includes the faulty phase and the phase-to-phase short circuit fault point, and the number of pulses or duration information of the current detected by the switch on the detection circuit is used to trigger tripping, thereby cutting off the fault point. Invention patent application 2021106183754 discloses a method for handling phase-to-phase short circuits in a three-phase power system. Partition switches and section switches are set on the line. The partition switch can cut off large currents, and the section switch only needs to cut off the load current. When a phase-to-phase short circuit occurs, the partition switch is controlled to trip by differential protection, and then the section switch is tripped by a method based on current pulses or current duration, thereby cutting off the phase-to-phase short circuit fault. In response to the situation where the power system uses two power sources as a backup power supply through a demarcation switch, invention patent application 202111251618.1 discloses a method for handling phase-to-phase short circuits in a dual-power three-phase power system. By constructing two detection loops, the current signal is used to disconnect the nearest sectionalizer switches on both sides of the phase-to-phase short circuit fault point, thereby completely eliminating the fault and achieving self-healing in the power system. This patent application uses a method of constructing two detection loops, which requires a lot of hardware, is complex to operate, and is not convenient to use. Summary of the Invention

[0004] The purpose of the present invention is to provide a power supply system that is easy to handle interphase short circuits. The system can cut off the sectionalizers closest to the two sides of the interphase short circuit fault point, thereby eliminating the short circuit fault and allowing the system to self-heal. The system is easy to operate, uses relatively less hardware, and has low cost.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A power supply system that is convenient for handling interphase short circuits includes a power supply and a three-phase line. A plurality of zoning switches are provided on the three-phase line. The zoning switches divide the three-phase line into a plurality of protection zones. A plurality of section switches are provided in the protection zones. The lower ports of the zoning switches are connected to the earth or a common conductor via a grounding switch. The busbar or system neutral point of the three-phase line is connected to the earth or the common conductor via a signal generating switch. The section switches can detect current signals and can trip according to preset current conditions. The section switches can also detect voltage signals and can trip according to preset voltage conditions.

[0007] Preferably, the section switch is provided with a storage unit, and the preset current condition and the preset voltage condition are stored in the storage unit.

[0008] Preferably, the preset current condition stored in the storage unit of a certain segment switch is the number of current pulses or the current duration, and the number of current pulses or the current duration of the segment switch close to the power supply is more than or longer than the number of current pulses or the current duration of the segment switch far away from the power supply.

[0009] Preferably, the preset voltage condition stored in the storage unit of a certain segment switch is that no voltage signal is detected after a preset time point, and the preset time point is the moment when the first segment switch of the segment switch toward the power supply side is assumed to trip according to the current condition.

[0010] Preferably, the preset voltage condition stored in the storage unit of a certain segment switch is that the segment switch detects no more voltage pulses after detecting a number of voltage pulses equal to the number of current pulses at which the first segment switch toward the power supply side of the segment switch is assumed to trip.

[0011] Preferably, the voltage signal is a phase voltage signal between a phase line of the three-phase line and the earth; or the voltage signal is a line voltage signal between two phase lines of the three-phase line; or the voltage signal is a 3U0 voltage signal of the three-phase line.

[0012] Preferably, the partition switch is a switch in which each phase can be controlled to be on or off individually.

[0013] Preferably, the partition switch is a switch that switches three phases on and off simultaneously, and is further provided with a parallel switch that can switch any phase that is cut off by the partition switch on again.

[0014] Preferably, a voltage-dropping resistor is connected in series between the grounding switch and the ground or the common wire.

[0015] Preferably, a current-limiting resistor is connected in series between the signal generating switch and the earth or the common wire, and a voltage-dropping resistor is connected in series between the grounding switch and the earth or the common wire. The sum of the resistances of the current-limiting resistor and the voltage-dropping resistor is 10-100 ohms.

[0016] In this power supply system, when a phase-to-phase short circuit fault occurs, a current signal can be injected into the detection circuit (the current signal is a current pulse signal that can be interrupted in the middle or an uninterrupted continuous current signal). The fault phase conductor between the fault point and the disconnected partition switch has an injected current flowing through it, and the corresponding section switch in this area can detect the injected current signal. The section switch closer to the fault point will have fewer pulses that trigger tripping or a shorter current duration. In this way, the section switch closest to the fault point that flows through the injected current (that is, can detect the current signal) will inevitably trip and cut off the current earlier than other section switches that can detect the current signal. In this way, other section switches will not trip again according to the current signal, thereby ensuring that only the section switch with current closest to the fault point is cut off. At the same time as the current signal is generated, a phase voltage relative to the earth or a line voltage between two lines or a 3U0 voltage will also be generated on the three-phase line. These voltage signals will be distributed on the conductors including the current segment switch and the no-current segment switch according to the principle of equal potential of the conductors (the voltage signal corresponds to the current signal, that is, a voltage pulse signal or a continuous voltage signal). In this way, when the current segment switch is cut off, the current signal disappears, and the corresponding voltage signal also disappears. At this time, the no-current segment switch will no longer detect the voltage signal. In the present invention, timing is performed from the moment when the current signal is started to be injected. According to the period and number of pulses of a single current pulse, the time point at which each segment switch is assumed to be triggered by the current signal to trip can be pre-planned (this time point is also a moment in the time series from the moment when the current injection starts). This time point plus the time taken for the mechanical action of the segment switch from starting to trip to completely tripping and cutting off the current can be used to obtain the pre-planned tripping moment of each segment switch. When a sectionalizer trips based on current conditions (this sectionalizer is the current-carrying sectionalizer closest to the fault point), the first sectionalizer downstream (the currentless sectionalizer closest to the fault point) can no longer detect a voltage signal from that moment on. Tripping based on this condition ensures that the currentless sectionalizer closest to the fault point will trip. Because each sectionalizer has a hypothetical tripping time planned in a time series (these tripping times are arranged sequentially in the time series), setting the voltage condition for triggering the tripping of a currentless sectionalizer to the point where no voltage signal is detected after the hypothetical tripping time of the first upstream sectionalizer will ensure that only that sectionalizer meets this condition (this currentless sectionalizer is also the currentless sectionalizer closest to the fault point). The other currentless sectionalizers will not trip because they can detect voltage signals after the planned tripping time of their respective upstream first sectionalizers. This ensures that only one currentless sectionalizer trips, preventing multiple currentless sectionalizers from tripping. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1Schematic diagram of the structure of the power supply system of the present invention using a grounding method (ellipsis in the figure indicates that the middle partition switch, segment switch, end load or another power supply at the end and the boundary switch separating the two power supplies are omitted, and the dotted box represents a protection zone);

[0018] Figure 2 This is a schematic diagram of the simulation circuit;

[0019] Figure 3 yes Figure 2 Enlarged image on the left;

[0020] Figure 4 yes Figure 2 Enlarged image on the right;

[0021] Figure 5 This is the phase voltage signal diagram of simulation example 1;

[0022] Figure 6 is the line voltage signal diagram of simulation example 1;

[0023] Figure 7 This is the 3U0 voltage signal diagram of simulation example 1;

[0024] Figure 8 is the phase voltage signal diagram of simulation example 2;

[0025] Figure 9 This is a schematic diagram of the structure of the power supply system of the present invention, which adopts the common conductor connection method (ellipsis in the figure represents the omission of the middle partition switch, section switch and the load at the end or another power supply at the end and the boundary switch separating the two power supplies, and the dotted box represents a protection zone). DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to specific embodiments in conjunction with the accompanying drawings:

[0027] like Figure 1 As shown, the power supply system includes a power source 1 and a three-phase line 2. Several section switches are installed on the three-phase line 2. A protection zone is defined between two adjacent section switches. A differential protection system can be installed on the section switches. When a phase-to-phase short circuit occurs within the protection zone, the differential protection system trips the section switches at the corresponding power inputs, thereby interrupting the fault current. Several section switches can be installed within each protection zone. These switches only need to interrupt the load current, not the high short-circuit current capability, to reduce costs.

[0028] If the interphase short circuit fault occurs at point F, the power supply system of the present invention has the following hardware configuration and corresponding operation mode when resolving the interphase short circuit fault:

[0029] First, use the zoning switch 4 at the power entrance of the protection zone 3 where point F is located to trip a faulty phase to cut off the fault current (assuming that phase C is cut off and phase B remains conductive. The specific method is to simultaneously cut off phases A, B, C, and C and then close phase B through the parallel switch 5 to restore the conduction of phase B. Alternatively, the single-phase switch 5 is not provided and the zoning switch 4 itself can be single-phase controlled, thereby only cutting off phase C and keeping phase B conductive from the beginning).

[0030] Then, connect phase C to the ground at the lower port of the tripped partition switch 4 through the grounding switch 6 and the voltage-dropping resistor 7. Then, connect phase A or phase C at the upper port of the tripped partition switch 4 (the entire conductor of phase A or the part of phase C located at the upper port of the partition switch 4 is energized, so they can be collectively referred to as energized phases. The specific upper port position is generally on the busbar of the power supply 1. In addition, it can also be grounded through the system neutral point) through the signal generating switch 8. Circular grounding or continuous grounding is thus constructed, thus constructing a detection loop including two fault phase conductors (i.e., BC phase conductors) and the phase-to-phase short-circuit point F, and generating current pulses or current durations. The two are collectively referred to as current signals (in a preferred embodiment, an adjustable current-limiting resistor 9 is connected in series between the signal generating switch 8 and the ground to better control the magnitude of the current signal). Simultaneously, due to the presence of the current signal, the provision of a voltage-dropping resistor 7 can also generate a voltage signal between the two faulty phase conductors (including the portion of the faulty phase conductor with a current signal and the portion of the faulty phase conductor without a current signal within the protected area) and the ground, thus generating a phase voltage signal. Alternatively, a line voltage signal can be generated between the two faulty phase conductors (this is limited to a two-phase short circuit and not applicable to a three-phase short circuit), or a 3U0 voltage signal can be generated. These voltage signals also correspond to current pulses or continuous currents, namely voltage pulse signals or voltage duration signals. Furthermore, if both the signal generating switch 8 and the grounding switch 6 are connected to the same common conductor 20, not to the ground, current and voltage signals for detection can also be generated.

[0031] In the above embodiment, the current signal and voltage signal are generated by cyclically disconnecting, connecting, or continuously connecting the signal generating switch 8. If the signal generating switch 8 is closed, and then the B phase is cyclically disconnected, connected, or continuously connected at the partition switch 4, or the C phase is cyclically disconnected, connected, or continuously connected at the grounding switch 6, the above current signal and voltage signal can be generated.

[0032] The segmentation switch has the ability to detect current pulses or current duration and voltage (it only needs to set a current sensor and a voltage sensor on the segmentation switch, which is a common technology in this field), and can trip according to the current signal and the undetected voltage signal. For example, in an embodiment of generating current pulses, the segmentation switch between the phase-to-phase short-circuit fault point and the segmentation switch 4 that has tripped has a current signal flowing through it, and the current pulse can be detected. Such a segmentation switch is recorded as a segmentation switch with current, and all segmentation switches in the entire protection zone are set to trip according to the current signal. The closer to the segmentation switch 4, the more current pulses that trip. For example, if there are 4 segmentation switches in the protection zone, the number of current pulses that trigger the tripping of the segmentation switch 10 farthest from the segmentation switch 4 is set to 1 (or 5, etc.), and the number of current pulses that trigger the tripping of the segmentation switch 11 above it is set to 2 (or 10, etc.). The number of circuit pulses required to trigger the tripping of the previous sectionalizer 12 is set to 3 (or 15, etc.), the number of current pulses required to trigger the tripping of the previous sectionalizer 13 is set to 4 (or 20, etc.), and the number of current pulses required to trigger the tripping of the section switch 4 can be set to 5 (or 20, etc.). Thus, after the current pulse is generated, no current pulse flows through sectionalizers 10 and 11 (after each phase-to-phase short-circuit fault occurs, sectionalizers with no current signal flowing and thus unable to detect current signals are recorded as no-current sectionalizers. The allocation of current-carrying and no-current sectionalizers varies with the location of the phase-to-phase short-circuit fault point), and thus no tripping is triggered. Thus, after the first current pulse is generated, no sectionalizer trips, nor does the second current pulse. After the third current pulse is generated, the current-carrying sectionalizer 12 closest to the fault point F meets the triggering condition and trips. After the trip, no current signal is generated in the detection circuit, so sectionalizer 13 will not trip again. In another embodiment for generating a continuous current, the current durations required to trigger the tripping of sectionalizers 10, 11, 12, and 13 are set to 100, 200, 300, and 400 milliseconds, respectively. Section switch 4 can be set to trip after 500 milliseconds (this will trigger the tripping of section switch 4 when the fault point is between section switch 13). Similarly, when the current persists for 300 milliseconds, section switch 12 trips. Prior to this, section switches 10 and 11 would not trip due to no current flowing through them. After section switch 12 trips, section switch 13 would not trip either due to the lack of current flowing through it. This ensures that the section switch closest to fault point F with current flowing through it trips. Those skilled in the art will appreciate that the time interval between two adjacent current pulses should be greater than the tripping time of the section switches. This prevents a current pulse from passing through section switch 12 while it is tripping, thereby preventing section switch 13 from tripping. Similarly, when tripping based on the current duration, the difference in the current durations required to trigger the tripping of the section switches should be greater than the tripping time of the section switches.

[0033] When the current signal exists, the section switches 10, 11, 12, and 13 will all detect the voltage signal, but in the logic setting, only the no-current switch will trip according to the voltage condition, and the current section switch with current flowing will not trip according to the voltage condition.

[0034] In one embodiment, within the entire protection zone 3, the condition for the sectionalizer to trip according to the voltage pulse signal is set to that a sectionalizer does not detect a voltage pulse after detecting a number of voltage pulses equal to the number of current pulses that triggered the tripping of the first sectionalizer upstream of the sectionalizer, and the upstream is the direction of counting the sectionalizers toward the tripped partition switch, or in other words, the direction toward the power supply side. In this embodiment, according to the number of current pulses that trigger the tripping of each of the above-mentioned sectionalizers, sectionalizer 13 trips because it does not detect the sixth voltage pulse, sectionalizer 12 trips because it does not detect the fifth voltage pulse, sectionalizer 11 trips because it does not detect the fourth voltage pulse, and sectionalizer 10 trips because it does not detect the third voltage pulse. Thus, after a phase-to-phase short circuit fault occurs at point F, when sectionalizer 12 trips according to the current condition, three current pulses have already been generated, accompanied by three voltage pulses. Since sectionalizer 12 has already tripped, the fourth voltage pulse will not be generated. Therefore, the no-current sectionalizer 11 trips. Since three voltage pulses have already been generated, the no-current sectionalizer 10 will not trip because it detects the third pulse. In this way, after a phase-to-phase short circuit fault occurs, the sectionalizers closest to the fault point can be successfully disconnected according to the current and voltage signals, thereby completely eliminating the fault and allowing the system to self-heal. For a system using two power supplies, since the section switches on both sides of the fault point have been cut off, the boundary switch can be closed to supply power to the line on the side of the section switch 11 away from the partition switch 4 (see invention patent application 202111251618.1 for details).

[0035] In another embodiment, the voltage condition for tripping the section switch is set as follows:

[0036] If the current pulse injected is a current pulse with a certain period, the moment when the current signal is first injected into the detection circuit is 0 and the timing starts. If the current pulse period is 100 milliseconds, the moment when the first current pulse flows through the sectionalizer 10 is the time point of 100 milliseconds. If the mechanical action time of the sectionalizer switch tripping is 50 milliseconds (that is, it takes 50 milliseconds for the sectionalizer switch to trip from the beginning to the complete tripping to cut off the current), the moment when the sectionalizer 10 trips is the 150th millisecond, and so on. The moment when the sectionalizer 11 trips is the 250th millisecond, the moment when the sectionalizer 12 trips is the 350th millisecond, the moment when the sectionalizer 13 trips is the 450th millisecond, and so on. Assume Fault point F is located between sectionalizers 12 and 11. According to the current condition, the sectionalizer 12 with current will trip at the 350th millisecond. After that, the sectionalizer 11 without current will no longer detect the voltage signal and can trip accordingly. The voltage condition for sectionalizer 10 to trigger tripping is that no voltage signal can be detected after 250 milliseconds (because the first switch upstream is sectionalizer 11, and the moment when sectionalizer 11 trips is 250 milliseconds). However, according to the current position of fault point F, sectionalizer 11 will not trip due to the current condition. Therefore, there is still a voltage signal after 250 milliseconds. In this way, sectionalizer 10 can detect the voltage signal, so it will not trip and will be locked. The same applies to other sectionalizers. This condition ensures that only the sectionalizer with no current closest to fault point F will trip, and other sectionalizers with no current will not trip. It is also irrelevant to the specific location where fault point F appears randomly.

[0037] If an uninterrupted continuous current is injected, an uninterrupted continuous voltage will be generated, and the above planning is also applicable, because the continuous current can still be regarded as a continuous current pulse with a fixed period, so it will not be repeated. Further generalization, even if the period of the current pulse is not fixed, the injection method can be pre-designed, and the period of each current pulse is also controllable. Therefore, the tripping time of any sectionalizer that trips according to the current condition can also be planned in advance. The tripping time should be planned according to the time when the first sectionalizer upstream of the sectionalizer is assumed to trip according to the above current condition after the injection of the current signal. The so-called assumed tripping means that the phase-to-phase short circuit fault point occurs between the sectionalizer that is assumed to trip and the next sectionalizer.

[0038] In a preferred embodiment, after the current limiting resistor 9 is connected in series between the signal generating switch 8 and the ground, the sum of the resistances of the voltage dropping resistor 7 and the current limiting resistor 9 is set to 100 ohms, preferably 50 ohms each.

[0039] In one embodiment, a differential protection system is provided in each protection zone. When a phase-to-phase short circuit fault occurs, the differential protection system sends a control signal to cause the corresponding zone switch to trip at least one faulty phase to cut off the fault current.

[0040] In one embodiment, after a current pulse or continuous current is generated in the detection circuit, the voltage signal generated between the fault phase conductor and another normal phase can be used (this is limited to two-phase short circuit, and not suitable for three-phase short circuit) to trip the no-current sectionalizing switch. At this time, when the current sectionalizing switch is tripped, the three phases need to be tripped at the same time. In this way, after the current sectionalizing switch is tripped, there is no longer voltage between the normal phase and the fault phase, and there is voltage between the normal phase and the fault phase before the current sectionalizing switch is tripped. This voltage is also a voltage pulse or continuous voltage. The no-current sectionalizing switch closest to the fault point is tripped by not detecting the corresponding number of voltage pulses or voltage duration.

[0041] Furthermore, the 3U0 voltage signal can be used as a criterion for tripping a no-current sectionalizer. This is because as long as the voltage signal detected by the no-current sectionalizer changes before and after the current sectionalizer closest to the fault point trips, the previously detected voltage signal will no longer recur. Therefore, logic can be designed to use voltage signals such as the number of undetected voltage pulses and the duration of undetected voltage as criterion.

[0042] In order to reveal the three-phase line voltage signal corresponding to the stages after the partition switch 4 cuts off the current, phase B remains conductive, phase C is grounded through the grounding switch 7, the signal generating switch 8 is grounded, and then the section switch 12 is tripped, the following simulation example is made (in the following simulation example, the partition switch 4 has a single-phase control function):

[0043] Simulation Example 1:

[0044] BC is short-circuited, and the partition switch 4 cuts off the three phases ABC; 0.02S, the partition switch 4 turns on the B phase; 0.06S, the grounding switch 6 is turned on and grounded; 0.15S to 0.25S, the signal generating switch 8 is turned on and grounded; 0.26S, the section switch 12 trips, and 0.3S, the section switch 11 trips.

[0045] After the fault point, the phase voltages Ua, Ub, and Uc detected by the section switch 11 are Figure 5 shown.

[0046] After the fault point, the line voltages Uab, Ubc, and Uca detected by the section switch 11 are as follows: Figure 6 shown.

[0047] After the fault point, the 3U0 voltage detected by the section switch 11 is as follows: Figure 7 shown.

[0048] Simulation Example 2:

[0049] 0.01S, BC short circuit; 0.02S, partition switch 4 trips phase C, and phase AB remains conductive; 0.06S, grounding switch 6 is conductive and grounded; 0.15S to 0.25S, signal generating switch 8 is conductive and grounded; 0.26S, section switch 12 trips; 0.3S, section switch 11 trips.

[0050] After the fault point, the phase voltages Ua, Ub, and Uc detected by the section switch 11 are as follows: Figure 8 shown.

[0051] The above simulation example shows that before the section switch 12 trips, the partition switch 11 can detect voltage signals such as phase voltage, line voltage, and 3U0 voltage. However, after the section switch 12 trips, the partition switch 11 will no longer detect voltage signals, and judgment can be made based on this.

[0052] The above embodiments are merely illustrative of the concept and implementation of the present invention, and are not intended to limit the same. Under the concept of the present invention, technical solutions that have not been substantially changed are still within the scope of protection.

Claims

1. A power supply system that facilitates handling of interphase short circuits, comprising a power supply and a three-phase line. The three-phase line is provided with a plurality of zone switches, the zone switches dividing the three-phase line into a plurality of protection zones. Within the protection zones are a plurality of section switches, the lower ports of the zone switches being connected to the earth or a common conductor via a grounding switch. The busbar or system neutral point of the three-phase line is connected to the earth or the common conductor via a signal generating switch. The section switches are capable of detecting current signals and tripping according to preset current conditions. The system is characterized in that: The section switch can also detect voltage signals and trip according to a preset voltage condition, wherein the preset voltage condition is that no voltage signal is detected after a preset time point, and the preset time point is the moment when the first section switch toward the power supply side of the section switch is assumed to trip according to the current condition; or the preset voltage condition is that the section switch detects no voltage pulses after detecting a number of voltage pulses equal to the number of current pulses at which the first section switch toward the power supply side of the section switch is assumed to trip.

2. The power supply system for facilitating handling of interphase short circuits according to claim 1, characterized in that: The section switch is provided with a storage unit, and the preset current condition and the preset voltage condition are stored in the storage unit.

3. The power supply system for facilitating handling of interphase short circuits according to claim 1, characterized in that: The voltage signal is a phase voltage signal between a phase line of the three-phase line and the earth; Or the voltage signal is a line voltage signal between two phases of the three-phase line; Alternatively, the voltage signal is the 3U0 voltage signal of the three-phase line.

4. The power supply system for facilitating handling of interphase short circuits according to claim 1, wherein: The partition switch is a switch in which each phase can be controlled to be on or off independently.

5. The power supply system for facilitating handling of interphase short circuits according to claim 1, characterized in that: The partition switch is a switch that switches three phases on and off simultaneously, and is further provided with a parallel switch that can switch any phase that is cut off by the partition switch on again.

6. The power supply system for facilitating handling of interphase short circuits according to claim 1, characterized in that: A voltage-dropping resistor is connected in series between the grounding switch and the ground or the common wire.

7. The power supply system for facilitating handling of interphase short circuits according to claim 1, characterized in that: A current limiting resistor is connected in series between the signal generating switch and the earth or the common wire, and a voltage dropping resistor is connected in series between the grounding switch and the earth or the common wire. The sum of the resistance values ​​of the current limiting resistor and the voltage dropping resistor is 10-100 ohms.

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