Three-phase power supply system without power failure of load after line fault

Abstract

The three-phase power supply system comprises a power supply line and a plurality of controlled units arranged on the power supply line, the left side and the right side of each controlled unit are connected with a first power source and a second power source respectively, and each controlled unit comprises a protective shell. A first switch and a second switch which are connected in series on the power supply line are arranged in the protective shell, the load is led out between the first switch and the second switch, and when an interphase short-circuit fault or a grounding fault occurs in the power supply line, the controlled unit adjacent to the fault point trips off the first switch or the second switch on the fault point side so as to keep supplying power to the load.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of power system protection, concretely relates to a three -phase power supply system of load not power -off after phase -to -phase short circuit fault or single -phase grounding fault. BACKGROUND

[0002] When the three -phase power supply system occurs phase -to -phase short circuit or single -phase grounding fault, the controlled switch can be opened according to the current duration or the number of current pulses, and when the phase -to -phase short circuit occurs, the two fault phases and the power supply are used to construct a detection loop, so that the detection loop generates a continuous detection current or current pulse, and the controlled switch is selectively opened according to the preset current duration or the preset number of current pulses, and finally a nearest controlled switch on the phase -to -phase short circuit fault point is tripped, so that the power -off area is accurately controlled below the controlled switch, and the purpose of reducing the power -off area is realized (CN113765056B, CN113725811B disclose similar processing methods for single -phase grounding fault). But from a higher requirement, the line controlled by the controlled switch will be powered off after the controlled switch is opened, and the power -off area may still be large, even if the two power sources are used in a hand -in -hand manner, and the controlled switch after the fault point is also opened and the remaining area is powered by another power source, but there are still multiple loads powered off between the two opened controlled switches. Therefore, how to further reduce the power -off area is still a technical problem that needs to be solved to improve the power supply quality and user experience. CONTENT OF UTILITY MODEL

[0003] The utility model aims at providing a three -phase power supply system of load not power -off after line fault, which can achieve the effect of load not power -off after phase -to -phase short circuit fault or single -phase grounding fault.

[0004] To achieve the above -mentioned purpose, the utility model adopts the following technical scheme:

[0005] The utility model relates to a kind of three-phase power supply system of load uninterrupted after line fault, including power supply line and the multiple controlled units being provided on the power supply line, the controlled unit is connected with first power supply and second power supply respectively on left and right sides, it is characterized by: the controlled unit includes protective shell, first switch and second switch are provided in protective shell and are connected in series on power supply line, load is led between first switch and second switch, when phase-to-phase short circuit or single-phase ground fault occurs, first switch and second switch on the both sides of fault point can be tripped according to the current condition or voltage condition set, the first power supply is power supply, and second power supply is standby power supply and is connected with power supply line by tie-in switch, or second power supply is also power supply.

[0006] Preferably, the first power supply and the second power supply are two independent power supplies.

[0007] Preferably, when the first power supply and the second power supply are both power supplies, the first power supply and the second power supply are the same power supply.

[0008] Preferably, the load is led by leading a wire, a switch or a drop-out fuse between the first switch and the second switch.

[0009] Optionally, when phase-to-phase short circuit fault or ground fault occurs, the first switch or the second switch on the side of the fault point is tripped by differential protection.

[0010] Optionally, when phase-to-phase short circuit fault occurs, the first breaker of the first power supply is tripped, and when the second power supply is also a power supply, the first breaker of the second power supply is also tripped, a detection loop is constructed, the detection loop includes two fault phases and the first power supply and can generate a characteristic current, the nearest controlled unit upstream of the fault point (i.e., close to the first power supply side) trips the first switch or the second switch on the side of the fault point according to the characteristic current information, and the nearest controlled unit downstream of the fault point (i.e., away from the first power supply side) trips the first switch or the second switch on the side of the fault point according to voltage information; when ground fault occurs, a detection loop is constructed, the detection loop includes one ground fault phase and the first power supply and can generate a characteristic current, the nearest controlled unit upstream of the fault point trips the first switch or the second switch on the side of the fault point according to the characteristic current information, and the nearest controlled unit downstream of the fault point trips the first switch or the second switch on the side of the fault point according to voltage information.

[0011] Optionally, the first switch and the second switch in the same controlled unit are provided with the same current condition and voltage condition for triggering the switch-off, when the first switch and the second switch in a certain controlled unit both reach the current condition for triggering the switch-off, the first switch or the second switch farther away from the first power supply is tripped, and when the first switch and the second switch in a certain controlled unit both reach the voltage condition for triggering the switch-off, the first switch or the second switch closer to the first power supply is tripped.

[0012] The utility model has the following beneficial effects: the structure of the controlled unit and the topological relation thereof with the load are redesigned, that is, the controlled unit comprises two switches, that is, the first switch and the second switch, and is designed such that the non-power-off load is only led out between the first switch and the second switch, and the two switches are both protected by the protection shell. Due to the protection of the protection shell, the controlled units on the three phases will not cause phase-to-phase short circuit or ground fault among them, that is, the phase-to-phase short circuit or ground fault only occurs between different phases of adjacent controlled units. At this time, the first switch or the second switch of the adjacent controlled units on both sides of the fault point can be tripped respectively. The controlled unit can keep supplying power to the load (or using the standby power supply to supply power) because it still has the second switch or the first switch closed respectively, thereby realizing the technical effect that the load led out between the first switch and the second switch of the controlled unit does not stop power supply. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The figure is a structural schematic view of the first embodiment of the utility model;

[0014] Figure 2 The figure is a structural schematic view of the second embodiment of the utility model;

[0015] Figure 3 The figure is a structural schematic view of the third embodiment of the utility model. DETAILED DESCRIPTION

[0016] The utility model will be further described below in combination with the drawings:

[0017] The first embodiment is as follows: Figure 1As shown, taking a 10kV three-phase power supply system as an example, the system comprises a first power supply 1 and a second power supply 2 and a power supply circuit 3, the first power supply 1 is a power supply for the power supply circuit 3, the second power supply 2 is a standby power supply for the power supply circuit 3, and the closing of a tie-in switch 4 can realize that the second power supply 2 supplies power to the power supply circuit 3. A plurality of controlled units 91, 92 and 93 are arranged on the power supply circuit 3, the controlled unit 91, the controlled unit 92 and the controlled unit 93 each comprise a protection shell 900 and a first switch 901 and a second switch 902 arranged in the protection shell 900, the first switch 901 and the second switch 902 are connected in series on the power supply circuit 3 and can each cut off the power supply circuit 3. A load 6 is led out between the first switch 901 and the second switch 902 on the power supply circuit 3, and the load 6 can be any device consuming electric energy, such as a 10kV voltage directly driven electric device, a 400V transformer and the like, which can lead out the load through a wire 7, lead out the load through a drop-out fuse 8, or lead out the load through a switch 5.

[0018] When a line fault occurs, the fault point F is located between two controlled units, such as Figure 1 the controlled unit 92 and the controlled unit 93 as shown, at this time, the second switch 902 in the controlled unit 92 on the left side of the fault point F is tripped, and at the same time, the first switch 901 in the controlled unit 93 on the right side of the fault point F is tripped, and the tie-in switch 4 is closed to utilize the second power supply 2 to supply power to the power supply circuit on the right side of the fault point F (when the first circuit breaker under the bus is tripped and then recloses, the fault point is excluded before reclosing, and the standby power supply is used to supply power according to the procedure, which is not treated as a power failure accident, which is also the meaning of "no power failure" of the utility model), so that the influence of the fault point F on the power supply circuit 3 is timely eliminated, and the load under the jurisdiction of the controlled unit 92 will not be powered off because the first switch 901 in the controlled unit 92 is always closed; the second switch 902 in the controlled unit 93 is always closed and the second power supply 2 has been put into use, so the load under the jurisdiction of the controlled unit 93 will not be powered off. Because the controlled units are each provided with a protection shell 900, the probability of phase-to-phase short circuit or single-phase ground fault occurring inside the controlled units is close to zero and can be ignored, so that it is realized that each load on the power supply circuit will not have a power failure accident.

[0019] When the first power supply 1 and the second power supply 2 are both power supplies, the first power supply 1 and the second power supply 2 are two independent power supplies with adjusted phase angles that can be combined to operate, or the first power supply 1 and the second power supply 2 are the same power supply, that is, the power supply circuit is two buses of the same transformer or two outgoing lines of the same bus or two different branch lines of the same outgoing line, the tie-in switch 4 is normally closed or a wire is replaced, the second switch 902 in the controlled unit 92 on the left side of the fault point F is tripped, at the same time, the first switch 901 in the controlled unit 93 on the right side of the fault point F is tripped, the fault is isolated, and the load is not powered off.

[0020] In the first embodiment, the corresponding second switch 902 and first switch 901 are tripped by differential protection. Specifically, differential protection is provided between the first switch 901 and second switch 902 of two adjacent controlled units connected to each other, forming a differential protection zone, as shown in Figure 1 Differential protection is provided between the first switch 901 of controlled unit 93 and the second switch 902 of controlled unit 92, between the second switch 902 of controlled unit 91 and the first switch 901 of controlled unit 92, and so on. When the inter-phase short-circuit fault point or single-phase grounding fault point F is located between the second switch 902 and first switch 901 of two adjacent controlled units provided with differential protection, the current flowing into and out of the differential protection zone at the same time is not equal and there is a difference, which exceeds the threshold value, and the second switch 902 and first switch 901 are tripped to isolate the fault point F.

[0021] In the second embodiment, as shown in Figure 2 , a branch line is led out between the first switch 901 and second switch 902 of controlled unit 92 instead of directly leading out the load as shown in Figure 1 , the controlled unit 94 and controlled unit 95 are provided on the branch line, which in turn lead out their respective loads, and two power supplies are also provided on the branch line. If the fault point occurs at point F' between the controlled units 92, 94, and 95, the controlled unit 92 trips the first switch 901 and second switch 902 adjacent to the fault point (as the fault point F' is located on the wire led out between the first switch 901 and second switch 902, at this time, the first switch 901 and second switch 902 can be considered to be adjacent to the fault point F'), the controlled unit 94 trips the second switch 902 adjacent to the fault point F', and the controlled unit 95 trips the first switch 901 adjacent to the fault point. In the second embodiment, differential protection is provided between the first switch and second switch of the controlled units 92, 94, and 95, and the fault point F' is located in the four-port differential protection zone, so the first switch 901 and second switch 902 of the controlled unit 92 and the second switch 902 of the controlled unit 94 and the first switch 901 of the controlled unit 95 can be tripped by the differential protection mechanism.

[0022] In the third embodiment, the corresponding second switch 902 and first switch 901 are tripped by characteristic current and characteristic voltage, as shown in Figure 3As shown, three-phase independent switch 7 is arranged on the busbar of first power supply 1 and grounded (or connected to the common conductor) through current-limiting resistor 8, and three-phase independent switch 10 is arranged on the outgoing line below the switch of first circuit breaker 9 and grounded (or connected to the same common conductor as switch 7). The first switch 901 and the second switch 902 in each controlled unit 91, 92, 93 on power supply line 3 can be tripped according to the current signal (including current duration or current pulse) or the voltage signal (including voltage duration or voltage pulse). Moreover, the farther the switch (first switch and second switch) is from first power supply 1, the shorter the current duration or the fewer the number of current pulses for triggering the switch to be tripped. For example, if phase-to-phase short-circuit fault point F occurs on BC two-phase between controlled unit 92 and controlled unit 93, the system detects overcurrent and trips first circuit breaker 9, then closes B-phase of auxiliary switch 81 of each phase of circuit breaker 9 to make the B-phase of circuit breaker 9 conductive, then closes C-phase of switch 7 to make busbar C-phase grounded or connected to the common conductor, and closes C-phase of switch 10 to make C-phase grounded or connected to the common conductor from the lower end of circuit breaker 9. In this way, through the ground or common conductor, first power supply 1, B-phase from first power supply 1 to fault point F, fault point F, C-phase from fault point F to the lower end of circuit breaker 9, C-phase in switch 10, ground, C-phase in switch 7, and first power supply form a detection loop, and a continuous current is generated. The nearest first switch 901 downstream of fault point F (i.e., away from first power supply in the detection loop) does not detect current because it is not in the detection loop. The nearest second switch 902 upstream of fault point F (i.e., close to first power supply in the detection loop) has a shorter preset current duration for triggering the switch to be tripped than the nearest first switch 901 upstream of the second switch 902. When the second switch 902 reaches the triggering duration, the second switch 902 is tripped. At this time, the current duration has not reached the duration for triggering the first switch 901 upstream of the second switch 902 to be tripped, so the first switch 901 is not tripped. In addition to using current duration, current pulse can also be used. For example, switch 7 can cyclically conduct and disconnect C-phase to generate current pulse. The condition for triggering each switch to be tripped is based on the number of detected current pulses. Moreover, the closer the switch is to first power supply, the more the number of current pulses for triggering the switch to be tripped. In the above detection loop, the nearest first switch 901 downstream of fault point F does not detect current pulse because it is not in the detection loop. The nearest second switch 902 upstream of fault point F has a smaller number of current pulses for triggering the switch to be tripped than the nearest first switch 901 upstream of the second switch 902. When the second switch 902 reaches the number of current pulses for triggering the switch to be tripped, the second switch 902 is tripped. At this time, the number of current pulses has not reached the number of current pulses for triggering the first switch 901 upstream of the second switch 902 to be tripped, so the first switch 901 is not tripped.

[0023] From the time when the current is detected, each switch (the first switch and the second switch) starts to detect the voltage, but only the switch that does not detect the current will trip according to the voltage condition, and the voltage condition that triggers the cut-off of a certain switch among the switches that do not detect the current is that the first switch (the first switch and the second switch) upstream of the certain switch does not detect the voltage signal after the scheduled trip time (or the number of pulses of the scheduled trip) of the first switch. In this way, the nearest first switch 901 after the fault point can be ensured to trip according to the preset voltage condition, and other switches without current flowing through them will not trip.

[0024] The algorithm for tripping according to the current condition and the voltage condition to exclude faults is described in detail in the invention patent application CN115117862A, especially paragraphs 0017 to 0030 and the corresponding drawings in the specific embodiment part of the patent application. The above patent application is introduced in its entirety (especially paragraphs 0017 to 0030 and the corresponding drawings) as further description. In terms of algorithm, the partition switches in the protection zone in the above patent application correspond to the first circuit breaker in the utility model, and the sectional switches correspond to the first switch and the second switch in the utility model. The flow section switches in the patent application correspond to the first switch and the second switch with current flowing through them in the utility model, and the no-flow section switches correspond to the first switch and the second switch without current flowing through them in the utility model.

[0025] Further, since only one of the first switch and the second switch inside the controlled unit needs to trip, the first switch and the second switch of the controlled unit can be set with the same current and voltage trigger cut-off conditions (i.e., the same current duration or current pulse number for triggering cut-off, or the same voltage condition for triggering cut-off), and the first switch and the second switch simultaneously reach the current trigger cut-off condition, and the switch far from the power supply side trips, and the first switch and the second switch simultaneously reach the voltage trigger cut-off condition, and the switch close to the power supply side trips. For example, Figure 3 , when the first switch 901 and the second switch 902 in the controlled unit 92 both reach the current duration or current pulse number for triggering cut-off, only the second switch 902 farther from the power supply is cut off, and when the first switch 901 and the second switch 902 in the controlled unit 93 both reach the voltage condition for triggering cut-off (i.e., no voltage is detected after the scheduled trip time or the number of voltage pulses of the previous switch), only the first switch 901 closer to the power supply is cut off. In this way, compared to setting different current duration or current pulse number for triggering cut-off for the first switch and the second switch in the same controlled unit, the current duration or current pulse number for triggering cut-off of the first switch and the second switch in each controlled unit can be set shorter or fewer in total, thereby shortening the required fault handling time as a whole, which is beneficial to reducing the number of stages of the entire line, and more beneficial to quickly isolating faults. For Figure 2In the case of the branch shown from the controlled unit 92, if the differential protection is not used and the characteristic current and characteristic voltage tripping mode is used: if the fault point occurs at point F', the first circuit breaker of the first power supply outgoing line is tripped, and a detection circuit is also constructed (if the other three power supplies are the same as the power supply, the second power supply is also required to be tripped at the same time), the detection circuit includes two fault phases and the first power supply and can generate a characteristic current, the first switch 901 in the controlled unit 92 located upstream of the fault point (i.e. close to the first power supply side) can detect the characteristic current and trip, the second switch 902 in the controlled unit 92, the second switch 902 in the controlled unit 94 and the first switch 901 in the controlled unit 95 will not detect the current, and will trip according to the preset voltage condition.

[0026] The above embodiments are only a description of the concept and implementation of the present application, and are not a limitation thereof. Under the concept of the present application, the technical solutions without substantial changes are still within the protection scope.

Claims

1. A three-phase power supply system that ensures uninterrupted power supply to the load after a line fault, comprising a power supply line and multiple controlled units mounted on the power supply line, wherein the left and right sides of each controlled unit are respectively connected to a first power source and a second power source, characterized in that: The controlled unit includes a protective housing, within which a first switch and a second switch are connected in series on the power supply line. The load is led out between the first switch and the second switch. The first switch and the second switch can trip the power supply line according to set current or voltage conditions. The first power source is the power supply, and the second power source is the backup power source connected to the power supply line via a connecting switch, or the second power source is also the power supply.

2. The three-phase power supply system that ensures uninterrupted power supply to the load after a line fault as described in claim 1, characterized in that, The first power supply and the second power supply are two independent power supplies.

3. The three-phase power supply system that ensures uninterrupted power supply to the load after a line fault as described in claim 1, characterized in that, When both the first power source and the second power source are power supplies, the first power source and the second power source are the same power source.

4. The three-phase power supply system that ensures uninterrupted power supply to the load after a line fault as described in claim 1, characterized in that, The load is drawn out by a wire, switch, or drop fuse between the first and second switches.

5. The three-phase power supply system that ensures uninterrupted power supply to the load after a line fault as described in claim 1, characterized in that, When a phase-to-phase short-circuit fault or a ground fault occurs, the first or second switch on the fault point side is tripped by the differential protection.

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