WO2023123640A1

WO2023123640A1 - Convenient and fast treatment method for inter-phase short circuit of three-phase electric power system

Info

Publication number: WO2023123640A1
Application number: PCT/CN2022/077128
Authority: WO
Inventors: 薛占钰; 杨贤; 邢进春; 丁同同
Original assignee: 保定钰鑫电气科技有限公司
Priority date: 2021-12-28
Filing date: 2022-02-21
Publication date: 2023-07-06
Also published as: CN115117862A

Abstract

Disclosed in the present invention is a convenient and fast treatment method for an inter-phase short circuit of a three-phase electric power system. The method comprises: firstly, cutting off a fault current; then, constructing a detection loop by using two fault phase wires and a fault point, injecting a current signal, and simultaneously generating a voltage signal; and detecting the current signal and the voltage signal by using section switches, wherein the section switch through which a current flows is disconnected according to a preset current signal, the section switch through which no current flows is disconnected according to the voltage signal, and the section switch with the current and the section switch without the current, which can trip, are section switches closest to two sides of the fault point. By means of the method, section switches closest to two sides of a fault point of an inter-phase short circuit can be disconnected, such that a short-circuit fault is removed to make a system self-healing; in addition, the operation is convenient and fast, relatively less hardware is used, and costs are relatively low.

Description

A convenient treatment method for phase-to-phase short circuit in three-phase power system

technical field

The invention relates to the field of power system protection, in particular to a convenient treatment method for interphase short circuit in a three-phase power system.

Background technique

Regarding the processing methods of phase-to-phase short circuit in three-phase power system, the current common methods are: 1. Adopt the method of reclosing: first cut off the first circuit breaker on the line and then close the first circuit breaker. If it is instantaneous If the short circuit between phases is eliminated after closing the first circuit breaker, the normal power supply will continue. If the phase-to-phase short-circuit fault still exists after closing the first circuit breaker, cut off the first circuit breaker and wait for maintenance. 2. Adopt the time-level difference coordination method: that is, the same line circuit breaker sets different over-current tripping times according to the distance from the power supply. The closer the distance to the power supply, the longer the tripping time. Generally, the setting level difference is 100ms. This time is determined by the mechanical switch. The action duration is determined by the time spent on the algorithm. This method can isolate the fault area. However, for faults where the fault point is close to the power supply, the power supply system can withstand short-circuit current for a long time and have a large impact on the power grid. 3. Trip the first circuit breaker for over-current first, then finally trip the load switch without current (other load switches are in the closed state), then reclose the first circuit breaker, if a fault occurs, the last load switch If the load switch is below the switch, the fault can be eliminated. Otherwise, there will still be a fault current after the first circuit breaker is reclosed. The circuit breaker is reclosed again. If the phase-to-phase short circuit occurs between the penultimate load switch and the last load switch, the fault can be eliminated. By analogy, turn off the load switch upwards without current until the fault is eliminated. However, during this operation, the power supply system is repeatedly subjected to large short-circuit current impacts. If there are too many times, it will cause damage to the line, and it will take a long time to troubleshoot the line. 4. The line is equipped with circuit breakers with fault current tripping capabilities. When a fault occurs, set all circuit breakers to overcurrent tripping, and then close the first circuit breaker. If there is an overcurrent, it will trip. Troubleshooting . If the first circuit breaker closes successfully without overcurrent, it will block the overcurrent trip for a period of time. During this period, the second circuit breaker is closed. Since the first circuit breaker has been blocked by overcurrent, the second If the circuit breaker has an overcurrent trip, the fault is eliminated. If there is no overcurrent, then close the next one, and so on. This solution requires each circuit breaker to have the ability to cut off large currents, which has high requirements for circuit breakers, high manufacturing costs, complex logic, and relatively long self-healing time. Therefore, the existing inter-phase short-circuit treatment methods all have the disadvantages of taking a long time to deal with the fault, having a large impact on the system, and requiring high capability of the switch to cut off a large current.

Invention patent application 202011453632.5 and invention patent application 202011453631.0 provide two methods for dealing with phase-to-phase short circuit. When a phase-to-phase short circuit occurs, a detection circuit including the faulty phase and phase-to-phase short circuit fault point is artificially constructed, and the switch on the detection circuit is used to detect the current. The pulse number or duration information triggers a trip to cut off the fault point. Invention patent application 2021106183754 discloses a method for dealing with phase-to-phase short-circuit in a three-phase power system. Partition switches and section switches are installed on the line. The section switches can cut off large currents, and the section switches only need to cut off the load current. The differential protection controls the tripping of the sub-section switch, and then uses the method of current pulse or current duration to trip the sub-section switch, thereby eliminating the phase-to-phase short circuit fault. Aiming at the situation that the power system uses two power sources as backup power supply for each other through the boundary switch, the invention patent application 202111251618.1 discloses a method for handling short circuits between phases in a three-phase power system with dual power sources. The nearest section switch is cut off on both sides of the short-circuit fault point, so that the power system can completely remove the fault and achieve self-healing. This patent application adopts the method of constructing the detection circuit twice, which requires a lot of hardware, is complicated to operate, and is not convenient enough to use.

technical problem

The purpose of the present invention is to provide a convenient treatment method for phase-to-phase short-circuit in a three-phase power system. This method can cut off the segment switches with the closest distance on both sides of the phase-to-phase short-circuit fault point so as to cut off the short-circuit fault and make the system self-healing, and the operation is convenient. The hardware is relatively reduced and the cost is low.

technical solution

In order to achieve the above object, the present invention adopts the following technical solutions: a convenient processing method for phase-to-phase short circuit of a three-phase power system, in which several partition switches are arranged on the three-phase power system, and the several partition switches divide the three-phase line into several In the protection area, there are several sub-section switches in the protection area, and the sub-section switches can detect current signals and voltage signals. It is characterized in that: when a phase-to-phase short-circuit fault occurs, it is processed as follows: S1: the protection of the phase-to-phase short-circuit fault point The partition switch in the zone is tripped to cut off the fault current; S2: use the two faulty phase conductors between the phase-to-phase short-circuit fault point to the partition switch that has been tripped and the phase-to-phase short-circuit fault point to construct a detection circuit, and send to the detection circuit Inject a current signal and generate a voltage signal; S3: The current segment switch in the protection zone where the phase-to-phase short-circuit fault point is located detects the current signal and the current segment switch closest to the phase-to-phase short-circuit fault point according to the preset current Conditional tripping, the current section switch is the section switch through which the current signal flows; S4: the no-current section switch in the protection zone where the phase-to-phase short-circuit fault point is located detects the voltage signal and is away from the phase-to-phase short-circuit fault The closest no-current section switch to the point trips according to a preset voltage condition, and the no-current section switch is a section switch through which the current signal does not flow.

Preferably, in step S3, the current condition is the number of current pulses to be detected or the duration of the current to be detected to trigger tripping of a certain section switch, and it is close to the section switch that has been tripped. The number of current pulses or the duration of the current of the section switch is more or longer than the number of current pulses or the duration of the current of the section switch far from the tripped section switch.

Preferably, in step S4, the voltage condition is that a certain section switch does not detect the voltage signal after the planned tripping time of the first section switch upstream of the section switch, and the Upstream is the direction of counting segment switches toward the skipped partition switch, and the planned jumping time is the first segment switch upstream of the segment switch according to the current from the injection of the current signal. Moments when conditional assumptions should be skipped.

Preferably, in step S4, the voltage condition is that a certain section switch detects a number of voltage pulses equal to the number of current pulses of the first section switch upstream of the section switch. A voltage pulse is detected again, and the upstream is in the direction of the counting section switch towards the tripped section switch.

Preferably, the voltage signal is a phase voltage signal between a certain phase line of the three-phase line and the ground; or the voltage signal is a line voltage signal between a certain two-phase line of the three-phase line; or The voltage signal is a 3U ₀ voltage signal of the three-phase line.

Preferably, the current signal and the voltage signal are generated using a power source of the three-phase power system.

Preferably, in step S1, the partition switch in the protection zone where the phase-to-phase short-circuit fault point is located jumps off at least one fault phase to cut off the fault current and maintain the conduction of another fault phase; The faulty phase is connected to the ground through the drop-down resistor from the lower port of the tripped partition switch, and then the live phase except the faulty phase that maintains conduction is connected and disconnected or continuously connected to the ground or the three-phase A neutral point of the power system is cyclically connected and disconnected or continuously connected to earth to generate said current signal and said voltage signal.

Preferably, in step S1, the maintaining another faulty phase conduction includes disconnecting the other faulty phase and then conducting the other faulty phase, or not disconnecting the other faulty phase so as to conduct from the beginning; In step S2, a signal generating switch is provided between the bus bar or neutral point of the three-phase power system and the ground, and the signal generating switch is cycled on and off or continuously turned on to generate the current signal or voltage signal.

Preferably, a current-limiting resistor is connected in series between the signal generating switch and the ground, and the sum of the resistance of the current-limiting resistor and the drop-down resistor is 10-100 ohms.

Preferably, the current signal and the voltage signal are generated by a power source other than the power source of the three-phase power system.

Beneficial effect

In the above scheme, when a current signal is 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 partition switch that has been cut off has an injected current. Correspondingly, the segment switch in this area can detect the injection current signal, and the segment switch closer to the fault point will trigger a trip with fewer pulses or a shorter current duration, so that the injection current that flows closest to the fault point (That is, the section switch that can detect the current signal) must trip and cut off the current before other section switches that can detect the current signal, so that other section switches will not trip again according to the current signal, so as to ensure that only the distance is cut off The nearest flow segment switch to the point of failure. When the current signal is generated, a certain phase voltage relative to the earth or a line voltage or 3U ₀ voltage between two lines will be generated on the three-phase line. On the wires including the segment switch and the non-current segment switch (the voltage signal corresponds to the current signal, that is, the voltage pulse signal or the continuous voltage signal), so that when the current segment switch is cut off, the current signal disappears, and the corresponding The voltage signal also disappears, and at this moment, the no-current section switch will no longer detect the voltage signal. In the present invention, timing is carried out from the moment when the current signal is started to be injected, and the time point at which each segment switch is assumed to be triggered by the current signal to trip can be pre-planned according to the cycle and the number of pulses of a single current pulse (this time point is also from the beginning A moment in the time series from the moment of current injection), this time point plus the time-consuming mechanical action of the section switch from the start of jumping to the complete tripping off of the current, the pre-planned tripping time of each section switch can be obtained . When a section switch jumps off according to the current condition (this section switch is the current section switch closest to the fault point), the first section switch downstream of it (the non-current section switch closest to the fault point) ) From this moment on, the voltage signal can no longer be detected. If the trip is based on this, the expectation of tripping of the nearest no-current section switch to the fault point can be realized. And because each sub-section switch is planned with a hypothetical tripping time in the time series (these tripping times are arranged sequentially in the time series), so the voltage condition for a certain no-current sub-section switch to trigger tripping is set as If no voltage signal is detected after the assumed tripping time of the first subsection switch upstream of it, only the subsection switch in question meets the conditions (this non-current subsection switch is also the non-current subsection closest to the fault point) section switch), and other no-current section switches will not trip because they can detect the voltage signal after the planned tripping time of the first section switch upstream respectively, which ensures that there is only one no-current section switch The switch trips without tripping multiple non-current section switches.

Description of drawings

Fig. 1 is a schematic diagram of the relevant structure of the three-phase power system in the method of the present invention adopting the method of connecting to the earth (the ellipsis in the figure represents the omission of the partition switch in the middle, the segment switch and the load at the end or another power supply at the end and the connection of the two power supplies separated demarcation switch, the dotted box represents a protection zone).

Figure 2 is a schematic diagram of the simulation circuit.

Figure 3 is an enlarged view of the left side of Figure 2 .

Figure 4 is an enlarged view of the right side of Figure 2 .

Fig. 5 is a diagram of the phase voltage signal of simulation example 1.

FIG. 6 is a line voltage signal diagram of simulation example 1. FIG.

Fig. 7 is the 3U ₀ voltage signal diagram of simulation example 1.

FIG. 8 is a phase voltage signal diagram of simulation example 2. FIG.

Fig. 9 is a schematic structural diagram of the power supply system of the method of the present invention adopting the method of connecting common wires.

(The ellipsis in the figure means omitting the partition switch in the middle, the section switch and the load at the end or another power supply at the end and the demarcation switch that separates the two power supplies, and the dotted line box represents a protection zone).

Embodiments of the present invention

Below in conjunction with the accompanying drawings, the present invention will be further described through specific embodiments: as shown in Figure 1, a three-phase power system includes a power supply 1 and a three-phase line 2, and several partition switches are arranged on the three-phase line 2, two adjacent There is a protection zone between the partition switches, and a differential protection system can be set on the partition switch. When a phase-to-phase short circuit occurs in the protection zone, the differential protection system controls the tripping of the corresponding power inlet partition switch to cut off the fault current. A number of section switches can be set inside each protection area. The section switches only need to have the ability to cut off the load current, and do not need to have the ability to cut off the short-circuit large current, so as to reduce costs.

Assuming that a phase-to-phase short-circuit fault occurs between the two phases of BC at point F, it is handled as follows: First, use the partition switch 4 of the electric energy entrance of the protection zone 3 where point F is located to jump off a faulty phase to cut off the fault current (assuming that C is cut off, To keep the B-phase conduction, the specific method is to cut off the ABC three-phase at the same time and then close the B-phase through the single-phase switch 5 to restore the B-phase conduction, or do not set the single-phase switch 5 and the partition switch 4 itself can be single-phase controlled. Thus only phase C is cut off and phase B remains on from the beginning).

Then, connect phase C to the ground through the grounding switch 6 and drop resistor 7 at the lower port of the partition switch 4 that has been tripped, and then connect phase A or phase C to the upper port of the partition switch 4 that has been tripped (phase A The part of the first wire or phase C located at the upper port of partition switch 4 is charged, so they can be collectively referred to as live phases. The specific upper port position is generally taken from the busbar of power supply 1, and can also be grounded through the neutral point of the system) through signal generation The switch 8 is cyclically grounded or continuously grounded, thus constructing a detection circuit including two faulty phase conductors (ie, BC phase conductors) and interphase short-circuit point F, and will generate current pulses or current durations, both of which are collectively referred to as current signals (In a preferred example, an adjustable current-limiting resistor 9 is connected in series between the signal generating switch 8 and the ground to better control the size of the current signal). It can be accompanied by the generation of a voltage signal between the two faulty phase conductors (including the faulty phase conductor part with current signal and the faulty phase conductor without current signal in the protection zone), which is the phase voltage signal, or with another Line-to-line voltage signals are generated between normal phases (at this time, only two-phase phase-to-phase short-circuit is not suitable for three-phase phase-to-phase short-circuit), or 3U ₀ voltage signals are generated. The above-mentioned voltage signal also corresponds to the current pulse or continuous current, that is, the voltage pulse signal or the voltage duration signal. In addition, if both the signal generating switch 8 and the grounding switch 6 are connected to the same common wire 20 instead of being connected to the ground, current signals and voltage signals for detection can also be generated.

The above-mentioned embodiment generates the current signal and the voltage signal by cyclically cutting off, conducting or continuously conducting the signal generating switch 8. If the signal generating switch 8 is closed, then the phase B is cyclically cut off, conducted or continuously conducted at the partition switch 4. conduction, or cyclically cut off, conduction or continuous conduction of phase C at the grounding switch 6, can generate the above-mentioned current signal and voltage signal.

The section switch has the ability to detect current pulse or current duration and voltage (only need to set current sensor and voltage sensor on the section switch, which is a common technology in this field), and can detect current signal and undetected voltage signal trip. For example, in an embodiment where current pulses are generated, current signals flow through the subsection switch between the phase-to-phase short-circuit fault point and the tripped partition switch 4, and current pulses can be detected. Such a subsection switch is denoted as There are current section switches, and all section switches in the entire protection zone are set according to the current signal tripping conditions so that the closer they are to section switch 4, the more current pulses will trip. For example, there are 4 section switches in this protection zone , then the number of current pulses triggered by the tripping of the section switch 10 farthest from the section switch 4 is set to 1 (or set to 5, etc.), and the number of current pulses triggered by the previous section switch 11 is set to 2 (or set to 10, etc.), and then set the number of circuit pulses for the tripping of the last section switch 12 to 3 (or set it to 15, etc.), and then set the number of current pulses for the tripping of the next section switch 13 to 4 (or set to 20, etc.), the number of current pulses for the tripping of the section switch 4 can be set to 5 (or set to 20, etc.), so that when the current pulse is generated, the section switches 10 and 11 have no current pulse flow (After each phase-to-phase short-circuit fault occurs, no current signal flows and the section switch that cannot detect the current signal is recorded as a no-current section switch, and the distribution of the current section switch and no-current section switch varies with Depending on the location of the short-circuit fault point), a trip will not be triggered. In this way, after the first current pulse is generated, there is no section switch tripping, and after the second current pulse is generated, there is no section switch tripping. When the third current pulse is generated, the current section switch 12 closest to the fault point F reaches The tripping condition is triggered, and no current signal is generated in the detection circuit after the tripping, so the section switch 13 will not trip again. In another embodiment in which continuous current is generated, the duration of tripping of the section switches 10, 11, 12, and 13 is respectively set to 100, 200, 300, and 400 milliseconds, and the section switch 4 can be set to trip in 500 milliseconds (when a fault When the point is between the partition switch 4 and the section switch 13, the partition switch will be tripped). In the same way, when the current lasts for 300 milliseconds, the section switch 12 trips. Before that, the section switches 10 and 11 will not trip because no current flows through. After the section switch 12 trips, because there is no more current, the section switch 13 will trip. It will not trip, so that the tripping of the current section switch closest to the fault point F can be guaranteed. Those skilled in the art can understand that the time interval between two adjacent current pulses should be greater than the time when the segment switch 12 jumps off, so that it will not happen that another current pulse passes through the segment switch 12 during the jump-off process to cause segmentation The switch 13 is also tripped. Similarly, when tripping according to the current duration, the difference in the current duration of the trip by the segment switch is greater than the time when the segment switch trips.

When the current signal exists, the segment switches 10, 11, 12, and 13 will all detect the voltage signal, but only the no-current switch will trip according to the voltage condition in the logical setting, and the current segment switch with current flowing will not trip according to the voltage condition. Voltage condition trips.

In one embodiment, in the entire protection zone 3, the sub-section switch is set to trip according to the condition of a voltage pulse signal when a certain sub-section switch detects the current that triggers tripping with the first sub-section switch upstream of the sub-section switch. No more voltage pulses are detected after the number of voltage pulses equal to the number of pulses, and the upstream is in the direction of counting the section switch towards the section switch that has been tripped. In this embodiment, according to the number of current pulses triggered by each section switch above, the section switch 13 does not detect the 6th voltage pulse and trips, and the section switch 12 does not detect the 5th voltage pulse and trips. The section switch 11 trips without detecting the fourth voltage pulse, and the section switch 10 trips without detecting the third voltage pulse, so that after a phase-to-phase short circuit fault occurs at point F, when the section switch 12 trips according to the current condition After opening, three current pulses have been generated at this time, correspondingly accompanied by three voltage pulses, and because the section switch 12 has been tripped, the fourth voltage pulse will not be generated, so the no-current section switch 11 trips , because three voltage pulses have been generated at this time, the no-current section switch 10 will not trip because it detects the third pulse. In this way, it is ensured that after a phase-to-phase short circuit fault occurs, the nearest section switches on both sides of the fault point can be cut off smoothly according to the current signal and voltage signal, so as to completely remove the fault and make the system self-healing. For a system using two power sources, 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 section switch 4 (for details, refer to the invention patent application 202111251618.1).

In another embodiment, the voltage condition for the tripping of the section switch is set as follows: if the injection is a current pulse with a certain period, the moment when the current signal is injected into the detection circuit at the beginning is 0 and starts timing, and the current pulse The period is 100 milliseconds, then the moment when the segment switch 10 flows through the first current pulse is the time point of 100 milliseconds, and the mechanical action of setting the segment switch to jump takes 50 milliseconds (that is, the segment switch jumps from the beginning to completely It takes 50 milliseconds to trip and cut off the current), then the moment when the section switch 10 trips is the 150th millisecond, and so on, the moment when the section switch 11 is tripped is the 250th millisecond, and the moment when the section switch 12 is tripped is the 250th millisecond. 350 milliseconds, the moment when the section switch 13 jumps is the 450th millisecond, etc., assuming that the fault point F is between the section switches 12 and 11, according to the current condition, the section switch 12 with flow jumps at the moment of the 350th millisecond After that, the no-current subsection switch 11 will no longer detect the voltage signal, and can trip accordingly, while the voltage condition for the subsection switch 10 to trigger tripping is that no voltage signal can be detected after the 250th millisecond (because of its upstream No. A switch is a section switch 11, and the moment when the section switch 11 trips is the 250th millisecond), but according to the current position of the fault point F, the section switch 11 will not trip due to the current condition, so after the 250th millisecond There is a voltage signal, so that the subsection switch 10 can detect the voltage signal, so it will not trip and block. The same is true for other section switches, so that this condition ensures that only the non-current section switch closest to the fault point F trips, and other non-current section switches do not trip, and has nothing to do with the specific location of the random occurrence of the fault point F .

If an uninterrupted continuous current is injected, an uninterrupted continuous voltage will be generated, and the above plan 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 described again. To further promote, even if the period of the current pulse is not fixed, how to inject the current can be pre-designed, and the period of each current pulse is also controllable, so the tripping time of any segment switch tripping according to the current condition It can also be planned in advance, and the tripping time should be planned according to the moment when the first subsection switch upstream of the subsection switch should be tripped according to the above current conditions from the injection current signal.

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 resistance of the drop-down resistor 7 and the current-limiting resistor 9 is set to 100 ohms, preferably 50 ohms each.

The above embodiments use the power supply of the three-phase power system itself to generate current signals and voltage signals. An external power supply can also be used to connect to the detection circuit containing two faulty phase conductors and a short-circuit fault point between phases. It can also generate current signals and voltage signals, such as current pulses, continuous currents, voltage pulses and continuous voltages. Sectional switches can also trip based on current conditions and voltage conditions for troubleshooting.

In one embodiment, a differential protection system is installed on each protection zone. When a phase-to-phase short circuit fault occurs, the differential protection system sends a control signal to make the corresponding partition switch jump at least one faulty phase to cut off the fault current.

In one embodiment, after the current pulse or continuous current is generated in the detection circuit, the voltage signal generated between the faulty phase conductor and another normal phase can be used (this time only limited to two-phase inter-phase short circuit, not suitable for three-phase inter-phase short circuit) to trip the non-current section switch. At this time, when the current section switch is tripped, the three phases need to be tripped at the same time, so that after the current section switch is tripped, there will be no voltage between the normal phase and the fault phase. , and there is a voltage between the normal phase and the fault phase before the current section switch trips, and this voltage is also a voltage pulse or continuous voltage. Sectional switch tripped.

In addition, the 3U ₀ voltage signal can also be used as the criterion for the tripping of the no-current section switch. Because as long as the voltage signal detected by the non-current section switch changes before and after the current section switch closest to the fault point trips, so that the original detected voltage signal does not repeat, the logic can be designed to eliminate the undetected Voltage signals such as the number of voltage pulses and undetected voltage duration are used as criteria.

In order to disclose the situation that phase B remains on after the partition switch 4 cuts off the current, phase C is grounded through the grounding switch 7, then the signal generating switch 8 is grounded, and then the section switch 12 jumps off the three-phase line voltage signal corresponding to these stages, Do the following simulation example (in the following simulation example, partition switch 4 has a single-phase control function).

Simulation example 1: BC short circuit, partition switch 4 cuts off ABC three-phase; 0.02S, partition switch 4 turns on phase B; 0.06S, grounding switch 6 conducts to ground; 0.15S to 0.25S, signal generation switch 8 conducts Grounding; 0.26S, section switch 12 trips, 0.3S, section switch 11 trips.

After the fault point, the phase voltages Ua, Ub, and Uc detected by the section switch 11 are shown in Fig. 5 .

After the fault point, the line voltages Uab, Ubc, and Uca detected by the section switch 11 are shown in FIG. 6 .

After the fault point, the 3U0 voltage detected by the section switch 11 is shown in FIG. 7 .

Simulation example 2: 0.01S, BC is short-circuited; 0.02S, partition switch 4 trips phase C, and phase AB remains on; 0.06S, grounding switch 6 is turned on and grounded; from 0.15S to 0.25S, signal generation switch 8 is turned on and grounded , 0.26S, section switch 12 trips, 0.3S, section switch 11 trips.

After the fault point, the phase voltages Ua, Ub, and Uc detected by the section switch 11 are shown in FIG. 8 .

The above simulation example shows that before the section switch 12 trips, the section switch 11 can detect voltage signals such as phase voltage, line voltage, and 3U ₀ voltage, but after the section switch 12 trips, the section switch 11 will no longer detect Voltage signal, based on which judgment can be made.

The above-mentioned embodiments are only illustrations of the concept and realization of the present invention, and are not intended to limit it. Under the concept of the present invention, technical solutions without substantial changes are still within the scope of protection.

Industrial Applicability

Through experiments in a three-phase power system, the above method is completely feasible.

Claims

A convenient treatment method for phase-to-phase short circuit in a three-phase power system, in which several partition switches are arranged on the three-phase power system, and the several partition switches divide the three-phase lines into several protection areas, and several sections are arranged in the protection area switch, the segmented switch can detect current signals and voltage signals, and is characterized in that: when a phase-to-phase short-circuit fault occurs, it is processed according to the following steps:

S1: The partition switch in the protection area where the phase-to-phase short-circuit fault point is located is tripped to cut off the fault current;

S2: Construct a detection circuit using two faulty phase wires between the phase-to-phase short-circuit fault point and the tripped partition switch and the phase-to-phase short-circuit fault point, inject a current signal into the detection circuit and generate a voltage signal;

S3: The current segment switch in the protection zone where the phase-to-phase short-circuit fault point is located detects the current signal and the current segment switch closest to the phase-to-phase short-circuit fault point trips according to the preset current condition, and the current segment The switch is a section switch through which the current signal flows;

S4: The no-current section switch in the protection zone where the phase-to-phase short-circuit fault point is located detects the voltage signal and the no-current section switch closest to the phase-to-phase short-circuit fault point trips according to the preset voltage condition, and the no-current section The switch is a segment switch through which the current signal does not flow.
The convenient processing method for phase-to-phase short circuit of a three-phase power system according to claim 1, characterized in that,

In step S3, the current condition is the number of current pulses to be detected or the duration of the current to be detected to trigger tripping of a certain section switch, and the section switch close to the tripped section switch The number of current pulses or the duration of the current is more or longer than the number of pulses of current or the duration of the current of the section switch far away from the tripped partition switch.
The convenient processing method for phase-to-phase short circuit of a three-phase power system as claimed in claim 2, characterized in that,

In step S4, the voltage condition is that a certain section switch does not detect the voltage signal after the planned tripping time of the first section switch upstream of the section switch, and the upstream is towards Count the direction of the section switch according to the section switch that has been tripped, and the planned trip time is the first section switch upstream of the section switch from the injection of the current signal according to the current condition. Time to jump away.
The convenient processing method for phase-to-phase short circuit of a three-phase power system as claimed in claim 2, characterized in that,

In step S4, the voltage condition is that a certain section switch detects no more voltage pulses after detecting the number of voltage pulses equal to the number of current pulses of the first section switch upstream of the section switch Voltage pulses, said upstream being in the direction of counting segment switches towards said tripped segment switch.
The convenient processing method for phase-to-phase short circuit of a three-phase power system according to claim 1, characterized in that,

The voltage signal is a phase voltage signal between a certain phase line of the three-phase line and the ground;

Or the voltage signal is a line voltage signal between a certain two-phase line of the three-phase line;

Or the voltage signal is a 3U 0 voltage signal of the three-phase line.
The convenient processing method for phase-to-phase short circuit in a three-phase power system according to claim 1, characterized in that the current signal and the voltage signal are generated by using a power source of the three-phase power system.
The convenient processing method for phase-to-phase short circuit of a three-phase power system as claimed in claim 6, characterized in that,

In step S1, the partition switch in the protection zone where the phase-to-phase short-circuit fault point is located jumps off at least one fault phase to cut off the fault current and maintain another fault phase conduction; The lower port of the tripped partition switch is connected to the ground through a drop-down resistor, and then the electrified phase except the faulty phase that maintains conduction is connected and disconnected or continuously connected to the ground or connected to the ground of the three-phase power system. The neutral point is cyclically connected and disconnected or continuously connected to earth to generate said current signal and said voltage signal.
The convenient processing method for phase-to-phase short circuit of a three-phase power system as claimed in claim 7, characterized in that:

In step S1, the maintaining another faulty phase conduction includes disconnecting the other faulty phase and then conducting the other faulty phase, or not disconnecting the other faulty phase so as to conduct from the beginning; in step S2 Among them, a signal generating switch is provided between the bus bar or neutral point of the three-phase power system and the ground, and the signal generating switch is cycled on and off or continuously turned on to generate the current signal or voltage signal.
The convenient processing method for phase-to-phase short circuit in a three-phase power system according to claim 8, characterized in that a current-limiting resistor is connected in series between the signal generating switch and the ground, and the resistance between the current-limiting resistor and the drop-down resistor is The sum of the values is 10~100 Euro.
The convenient processing method for phase-to-phase short circuit in a three-phase power system according to claim 1, characterized in that the current signal and the voltage signal are generated by a power source other than the power source of the three-phase power system.