CN111157844A

CN111157844A - Distribution line self-adaptive reclosing method and fault property identification method and device

Info

Publication number: CN111157844A
Application number: CN202010011152.7A
Authority: CN
Inventors: 吴水兰; 张建雨; 孟乐; 李俊刚; 庞建伟; 郭晓宁; 刘洋; 姜睿智; 崔龙卫; 常彦彦; 冀娟; 陈晓民
Original assignee: Xuji Group Co Ltd; XJ Electric Co Ltd; Xuchang XJ Software Technology Co Ltd
Current assignee: Xuji Group Co Ltd; XJ Electric Co Ltd; Xuchang XJ Software Technology Co Ltd
Priority date: 2020-01-06
Filing date: 2020-01-06
Publication date: 2020-05-15

Abstract

The invention relates to a distribution line self-adaptive reclosing method, a fault property identification method and a device, which comprise the following steps: if an asymmetric interphase short circuit fault occurs, putting capacitors into interphase loops corresponding to the two phases with the fault; if a symmetrical three-phase short circuit fault occurs, putting capacitors into phase-to-phase loops corresponding to any two phases; detecting the capacitor voltage and/or the capacitor current after the capacitor is put into operation, and judging whether the capacitor voltage and/or the capacitor current meet the permanent fault identification criterion; if so, judging that the line has a permanent fault, otherwise, judging that the line has a transient fault; when the line has permanent fault, the reclosing is locked, and when the line has transient fault, the reclosing is opened. The invention only needs to judge the transient characteristics of the voltage and the current of the capacitor, and when one of the two quantities can not be accurately obtained, the other quantity can be adopted to judge the fault type, thereby effectively improving the reliability of reclosing control.

Description

Distribution line self-adaptive reclosing method and fault property identification method and device

Technical Field

The invention relates to a distribution line self-adaptive reclosing method, a fault property identification method and a fault property identification device, and belongs to the technical field of relay protection.

Background

Because the line faults are more transient faults, when the line has transient faults, the reclosing can quickly recover the system power supply, and the power supply reliability of a power grid is greatly improved. However, when a permanent fault occurs in the line, a second impact is brought to the system after the reclosing action, which is not beneficial to the service life of the breaker and the stability of the power grid.

Chinese patent application publication No. CN107394757A discloses a method for identifying faults before phase-to-phase fault reclosing of a power distribution network, which can determine the type of the fault and perform reclosing operation according to the fault type, but the method is complicated in process, involves many parameters, and requires complicated calculation. The complex process corresponds to low reliability in implementation, the control system has heavy burden in executing the software program corresponding to the method, and the requirement on hardware of the control system is high.

In order to solve the problem that the reclosing method is complicated in process, Chinese patent document with the authorization publication number of CN108899864B discloses a distribution line self-adaptive reclosing method and a fault property identification method. However, the device of this method needs to connect the system between the circuit breaker and the current transformer, which is very inconvenient; in addition, the method needs to acquire the three-phase current information of the distribution line, and when any phase current information cannot be acquired or is acquired incorrectly, the fault type judgment is inaccurate, so that the reclosing control is unreliable.

Disclosure of Invention

The invention aims to provide a distribution line self-adaptive reclosing method, a fault property identification method and a device, which are used for solving the problem that reclosing control is unreliable due to the fact that more information is collected and any sampling information is inaccurate.

In order to solve the technical problem, the invention provides a distribution line self-adaptive reclosing method, which comprises the following steps:

if an asymmetric interphase short circuit fault occurs, putting capacitors into interphase loops corresponding to the two phases with the fault; if a symmetrical three-phase short circuit fault occurs, putting capacitors into phase-to-phase loops corresponding to any two phases;

detecting the capacitor voltage and/or the capacitor current after the capacitor is put into operation, and judging whether the capacitor voltage and/or the capacitor current meet the permanent fault identification criterion; if so, judging that the line has a permanent fault, otherwise, judging that the line has a transient fault;

when the line has permanent fault, the reclosing is locked, and when the line has transient fault, the reclosing is opened.

In order to solve the technical problem, the invention also provides a distribution line fault property identification method, which comprises the following steps:

detecting the capacitor voltage and/or the capacitor current after the capacitor is put into operation, and judging whether the capacitor voltage and/or the capacitor current meet the permanent fault identification criterion; if so, judging that the line has a permanent fault, otherwise, judging that the line has a transient fault.

In order to solve the technical problem, the invention further provides a distribution line adaptive reclosing control device, which comprises a capacitor, a voltage detection module and/or a current detection module, wherein the capacitor is used for being input into any two corresponding phase-to-phase loops of a line, the voltage detection module is used for detecting the voltage of the capacitor, the current detection module is used for detecting the current of the capacitor, the main control unit is connected with the voltage detection module and/or the current detection module in a sampling mode, the main control unit is provided with a communication port for being in communication connection with a feeder terminal, and the main control unit is used for: receiving fault type information sent by a feeder terminal, and putting capacitors into interphase loops corresponding to two phases with faults if the asymmetric interphase short circuit faults occur; if a symmetrical three-phase short circuit fault occurs, putting capacitors into phase-to-phase loops corresponding to any two phases; receiving the capacitor voltage and/or the capacitor current sent by the voltage detection module and/or the current detection module, and judging whether the capacitor voltage and/or the capacitor current meet the permanent fault identification criterion; and if so, judging that the line has a permanent fault, otherwise, judging that the line has a transient fault, and sending the information of the permanent fault or the transient fault to the feeder line terminal for locking the reclosure when the line has the permanent fault and opening the reclosure when the line has the transient fault.

In order to solve the technical problem, the invention further provides a distribution line fault property identification device, which comprises a capacitor, a voltage detection module and/or a current detection module, wherein the capacitor is used for being input into any two corresponding phase-to-phase loops of a line, the voltage detection module is used for detecting the voltage of the capacitor, the current detection module is used for detecting the current of the capacitor, the main control unit is connected with the voltage detection module and/or the current detection module in a sampling mode, the main control unit is provided with a communication port for being in communication connection with a feeder terminal, and the main control unit is used for: receiving fault type information sent by a feeder terminal, and putting capacitors into interphase loops corresponding to two phases with faults if the asymmetric interphase short circuit faults occur; if a symmetrical three-phase short circuit fault occurs, putting capacitors into phase-to-phase loops corresponding to any two phases; receiving the capacitor voltage and/or the capacitor current sent by the voltage detection module and/or the current detection module, and judging whether the capacitor voltage and/or the capacitor current meet the permanent fault identification criterion; if so, judging that the line has a permanent fault, otherwise, judging that the line has a transient fault.

The invention has the beneficial effects that: if an asymmetric interphase short-circuit fault occurs, a capacitor is put into an interphase loop corresponding to the two phases with the fault, if a symmetric three-phase short-circuit fault occurs, a capacitor is put into any interphase loop corresponding to the two phases, and the fault is determined to be permanent and to be closed and reclosed by detecting the current or voltage change condition at two ends of the capacitor, namely when the capacitor voltage is attenuated quickly or the amplitude of the capacitor current is large, or the fault is determined to be instantaneous and to be opened and reclosed. Because the invention only needs to judge the transient characteristics of the voltage and the current of the capacitor, when one of the two quantities can not be accurately obtained, the other quantity can be adopted to judge the fault type, and the reliability of reclosing control is effectively improved.

As a further improvement of the method, for reliable determination of the nature of the fault, the permanent fault identification criterion comprises: the sudden change time of the capacitor voltage is smaller than a first set time threshold or the sudden change time of the capacitor current is larger than a second set time threshold; the sudden change time of the capacitor voltage refers to the time taken by the capacitor voltage to decay from a first set voltage value to a second set voltage value, and the sudden change time of the capacitor current refers to the time taken by the absolute value of the capacitor current to be larger than a set current value.

As a further improvement of the method, in order to reliably judge the nature of the fault, the first set voltage value has a value range of 281V, the second set voltage value has a value range of 50V, and the set current value has a value range of 20A.

As a further improvement of the method, in order to achieve reliable determination, when a symmetrical three-phase short-circuit fault occurs, a capacitor is put into the two-phase circuit corresponding to the minimum phase voltage.

Drawings

Fig. 1 is a structural diagram of a distribution line adaptive reclosing control device of the present invention;

FIG. 2 is a charge on control logic diagram for the capacitor of the present invention;

FIG. 3 is a diagram of the charge completion control logic for the capacitor of the present invention;

FIG. 4 is a discharge completion control logic diagram of the capacitor of the present invention;

FIG. 5 is a control logic diagram of the fault identification enabled of the present invention;

FIG. 6(a) is a logic diagram of the isolation and earth-isolation control in the fault identification process of the present invention;

FIG. 6(b) is a control logic diagram of relays K1, K3 of the fault identification process of the present invention;

FIG. 6(c) is a control logic diagram of relays K2, K4 of the fault identification process of the present invention;

FIG. 6(d) is a control logic diagram of relays K1, K4 of the fault identification process of the present invention;

FIG. 6(e) is a logic diagram of the blade separation and ground blade combination control in the fault identification process of the present invention;

FIG. 6(f) is a logic diagram of the closing and blocking control in the fault identification process of the present invention;

FIG. 7 is an equivalent circuit diagram of a transient fault corresponding to an asymmetric interphase short-circuit fault of the present invention;

FIG. 8 is an equivalent circuit diagram of a permanent fault corresponding to an asymmetric interphase short-circuit fault of the present invention;

FIG. 9 is a logic diagram of the identification of permanent faults of the present invention;

FIG. 10 is a reclosing control logic diagram for a permanent fault of the present invention;

FIG. 11 is an equivalent circuit diagram of a transient fault corresponding to a symmetrical three-phase short fault of the present invention;

fig. 12 is an equivalent circuit diagram of a permanent fault corresponding to a symmetrical three-phase short-circuit fault of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Distribution lines self-adaptation reclosing controlling means embodiment:

the embodiment provides a distribution lines self-adaptation reclosing controlling means, as shown in fig. 1, including energy storage capacitor C, condenser throw-in circuit, voltage detection module, current detection module and main control unit, main control unit is provided with and is used for communication connection feeder terminal in order to obtain the communication port of fault type, and main control unit sampling connects voltage detection module and current detection module to control connection condenser throw-in circuit.

As shown in fig. 1, the capacitor input circuit includes a first connection line, a second connection line, a third connection line, and a fourth connection line. Phase A is connected to the positive pole of capacitor C through a first connecting circuit, phase B is connected to the positive pole of capacitor C through a second connecting circuit, phase B is connected to the negative pole of capacitor C through a third connecting circuit, and phase C is connected to the negative pole of capacitor C through a fourth connecting circuit. A switch K1 is arranged on the first connecting line in series, a switch K2 is arranged on the second connecting line in series, a switch K3 is arranged on the third connecting line in series, and a switch K4 is arranged on the fourth connecting line in series. In the embodiment, the switches K1 to K4 are all relay switches, and the main control unit controls and connects the relay switches K1 to K4. The capacitor input circuit described above has a function of inputting a capacitor into any two phase-to-phase circuit corresponding to two phases of a line, and it is needless to say that other circuits which can achieve the function in the related art may be adopted as other embodiments.

In order to detect the voltage and the current of the capacitor C, the voltage detection module and the current detection module may adopt any matched voltage detection device and current detection device in the prior art, and in this embodiment, the current detection module is a Current Transformer (CT).

In order to charge and discharge the capacitor C, the distribution line self-adaptive reclosing control device further comprises a charging line and a discharging line, and the charging line and the discharging line are both used for being connected with the capacitor C. In this embodiment, as shown in fig. 1, a transformer, an isolation module and a rectification module are disposed in the power supply line, a primary side of the transformer is used for connecting an ac power source, a secondary side of the transformer is connected to an input end of the isolation module, an output end of the isolation module is connected to an ac input end of the rectification module, and a dc output end of the rectification module is used for connecting a capacitor C. Between the direct current output end of the rectifying module and the capacitor C, charging switches K5 and K6 are further arranged, when the charging switches K5 and K6 are closed, the capacitor C is charged through the charging circuit, and when the charging switches K5 and K6 are opened, the capacitor C is stopped being charged through the charging circuit. The discharging branch is provided with a resistor R3 and a discharging switch K7 in series, and when the discharging switch K7 is closed, the capacitor C discharges through the resistors R1 and R3 and the discharging switch K7. In this embodiment, the switches K5-K7 are all relay switches, and the main control unit controls and connects the relay switches K5-K7.

The charging circuit and the discharging circuit are only given as a specific embodiment for charging and discharging the capacitor, and of course, other structures in the prior art may be adopted as other embodiments for charging and discharging the capacitor.

The distribution line adaptive reclosing control device is matched with the feeder line terminal together to finish fault property identification and adaptive reclosing, and the working principle is as follows: when a short-circuit fault occurs in a line, the feeder line terminal completes fault removal and fault phase selection according to fault characteristics, and sends a fault phase selection signal to the main control unit when reclosing is started. When the main control unit receives a fault phase selection signal of the feeder line terminal, the capacitor is controlled to exit a charging state, the capacitor is put into a primary circuit and is discharged through the primary circuit, the fault type is judged to be a permanent fault or a transient fault through current and voltage information acquisition and algorithm identification in the discharging process of the capacitor, and the fault property is sent to the feeder line terminal. After the feeder line terminal receives the fault property, if the fault property is a permanent fault, instantaneously discharging the reclosure; if the fault is transient fault, the reclosing is not discharged, but the closing outlet can not be driven.

In addition, when the distribution line adaptive reclosing control device needs to be overhauled, the disconnecting knife switch (disconnecting knife) and the grounding knife switch (grounding knife) are driven to be opened and closed firstly. The capacitor discharge can then be achieved using both hardware and software methods. The hardware method comprises the following steps: a three-station handle is adopted, one gear is charged, and the three-station handle is used as a hard pressing plate with a fault identification function; the first gear is a neutral gear, when the first gear is used, the fault identification function hard pressing plate is withdrawn, the relay switches K5 and K6 are switched off, and the charging is not carried out any more; the other gear is discharging, the contact of the gear is connected in parallel with the relay switch K7, the capacitor is discharged, and the device can be overhauled after discharging. The software method comprises the following steps: adopt the soft clamp plate of fault identification function, this soft clamp plate can not overhaul when putting into. When the soft pressing plate is withdrawn, the relay switches K5 and K6 are firstly disconnected, the electric appliance switch K7 is closed after 20ms, the capacitor is discharged, and the device can be overhauled after the discharge is finished. After the overhaul is finished, the soft pressure plate with the fault recognition function is firstly put into the relay switch K7 to be disconnected, the three-station handle is turned to a charging gear, then the relay switches K5 and K6 are put into logic according to the capacitor, and the permanent fault recognition device can recover the normal operation state.

Based on the above-mentioned distribution line adaptive reclosing control device, this embodiment also provides a distribution line adaptive reclosing method, where the fault types applicable to the distribution line adaptive reclosing method are an asymmetric interphase short-circuit fault and a symmetric three-phase short-circuit fault, and therefore, the distribution line adaptive reclosing method includes a reclosing strategy for the asymmetric interphase short-circuit fault and/or a reclosing strategy for the symmetric three-phase short-circuit fault, that is, the reclosing method may include any one of the two reclosing strategies, or both the two reclosing strategies, and this embodiment takes the case where both the reclosing strategies are included as an example.

The reclosing strategy aiming at the fault type of the asymmetric interphase short circuit fault comprises the following steps:

(1) when an asymmetric interphase short-circuit fault occurs, capacitors are put into interphase loops corresponding to the two phases with the fault.

(2) And detecting the capacitance voltage and the capacitance current of the capacitor after the capacitor is put into use, judging that the line has a permanent fault when the capacitance voltage and the capacitance current meet the permanent fault identification criterion, and otherwise, judging that the line has an instantaneous fault.

(3) When the line has permanent fault, the reclosing is locked, and when the line has transient fault, the reclosing is opened.

The reclosing strategy aiming at the three-phase short-circuit fault with the symmetrical fault type comprises the following steps:

1) when a symmetrical three-phase short circuit fault occurs, capacitors are put into any two phase circuits corresponding to two phases.

2) And detecting the capacitance voltage and the capacitance current of the capacitor after the capacitor is put into use, judging that the line has a permanent fault when the capacitance voltage and the capacitance current meet the permanent fault identification criterion, and otherwise, judging that the line has an instantaneous fault.

3) When the line has permanent fault, the reclosing is locked, and when the line has transient fault, the reclosing is opened.

For the two reclosing strategies, before the capacitor is put into use, that is, before the reclosing method is implemented, the fault type needs to be judged first, and since the fault type judgment mode belongs to the conventional technology and is irrelevant to the protection point of the invention, the specific description is not provided here. Such as: and judging the fault type according to the negative sequence voltage, judging as an asymmetric interphase short-circuit fault and selecting two phases with smaller line voltage as fault phases if the negative sequence voltage U2 is greater than a set value (such as 6V) during line fault, otherwise, judging as a symmetric three-phase short-circuit fault and selecting the interphase with the minimum line impedance amplitude as a fault phase. Moreover, the fault type judging process and the reclosing method are two independent method processes, and the fault type judging process can be a part of the reclosing method or not.

The feeder line terminal sends the phase selection information to the main control unit after judging the fault type of the line. For example, when the reclosing is started, the feeder terminal encodes the fault phase selection information into three paths of fault phase selection information 1, fault phase selection information 2 and fault phase selection information 3, and sends the three paths of fault phase selection information 1, fault phase selection information 2 and fault phase selection information 3 to the main control unit, and the coding rule of the fault phase selection information is shown in table 1. And after the main control unit receives the phase selection information of the feeder line terminal, the energy storage capacitor is controlled to exit from a charging state and put into a primary line to enter a discharging state. The throw-in point and the interphase short contact of the capacitor C are positioned between the line switch and the CT, and the capacitance current after the capacitor C is thrown in is detected through the CT.

TABLE 1

Since the state of the capacitor at the time of charging is a charged state, the charged capacitor may be charged directly or an uncharged capacitor may be charged online by a charging line. In the present embodiment, in order to realize the charging control of the capacitor, as shown in fig. 2, when the fault-recognition hard pressing plate is turned on, the fault-recognition soft pressing plate is turned on, the device self-checks normally, the fault-recognition start flag does not exist, and the delay time is 15 seconds, the relay switches K5 and K6 are controlled to be closed, and the capacitor charging input flag is set. In addition, as shown in fig. 3, when the capacitance voltage of the capacitor is measured to be more than 300V, the delay spread is eliminated for 0.2s, and the charged capacitance flag is set. As shown in FIG. 4, when the measured capacitance voltage of the capacitor is less than 30V, the delay spread is eliminated for 0.2s, and the capacitor discharge flag is set.

In this embodiment, the specific implementation process of the fault identification is as follows: after the main control unit receives the fault phase selection information and starts, the jitter is eliminated for 20ms, the rising edge triggers a fault identification starting mark, and the starting mark is widened for 10 s. The fault phase selection information is input into 1, input into 2 and input into 3, which represent three fault phase selection. The logic diagram of the fault identification initiation is shown in fig. 5. In fig. 5, for example, when the fault identification is started due to the fault selection of the AB phase fault, when the fault selection information switch 1 is satisfied, and the fault selection information switch-in 2, the fault selection information switch-in 3, the fault selection of the BC phase fault and the selection of the CA phase fault are not satisfied, the time is delayed for 20ms and is widened for 20ms, the time is delayed for 1ms and is widened for 10s after the falling edge is confirmed, and the fault identification is started when the fault selection of the AB phase fault is failed. And after the fault identification is started for 0s, clearing the capacitor charging input mark and disconnecting the relay switches K5 and K6. As shown in fig. 6(a), after the fault identification is started for 0.1s, the isolation switch is driven to be closed, the grounding switch is driven to be opened, the pulse width is continued for 3s, and the isolation switch is put into a primary system for about 3 s. As shown in fig. 6(b) to (d), after the fault recognition is started for 3.1s, the relay switches K1, K2, K3 and K4 are controlled to be closed according to the rule in table 2 according to the phase of the fault, and the pulse widths of the closed relay switches K1, K2, K3 and K4 are kept for 0.5 s. And judging whether the fault is a permanent fault or a transient fault within the pulse width output time. When the pulse width output is finished, if the permanent fault occurs, the locking reclosing outlet is driven to output the pulse width of 0.2 s; if the fault is transient fault, the closing reclosing outlet is not driven. As shown in fig. 6(e), after the fault identification is started for 4s, the isolation switch is driven to open and close the outlet, and the pulse widths of the isolation switch and the grounding switch continue for 3s, so that the isolation switch exits from the primary system and the grounding switch is driven to be grounded. As shown in fig. 6(f), when the isolation knife switch is in the closed position, the closing outlet is driven to be closed.

TABLE 2

Opening into 1	Opening into 2	Opening 3	Phase of failure	K1-K4 closure rules
					1	0	0	AB phase failure	K1, K3 closure
0	1	0	Failure of BC phase	K2, K4 closure
					0	0	1	Failure of CA phase	K1, K4 closure
0	0	0	Without failure	Is free of

A specific example of the two reclosing strategies is given below.

Aiming at the asymmetric interphase short circuit fault of the fault type:

the asymmetric interphase short-circuit fault is exemplified by an AB interphase fault. Then, the two phases that fail are the a phase and the B phase, and the C phase is the normal phase. When the main control unit receives the phase selection signal of the feeder terminal, the capacitor is controlled to exit the charging state, and the capacitor is put into the interphase loop corresponding to the two failed phases (namely, the failed interphase loop), namely, the capacitor is put into the interphase loops of the phase a and the phase B, and the phase C is not connected, as shown in fig. 7 or fig. 8. The capacitor voltage current characteristics at permanent and transient faults are analyzed by the AB phase-to-phase faults in fig. 7 and 8 as follows:

as shown in fig. 7, when a transient fault occurs in the line, the fault circuit is insulated and recovered, the capacitor is discharged from phase a to phase B through the load resistance, and the total impedance of the capacitor discharge circuit is large due to the fault recovery, that is: the voltage attenuation is slow and the current is small.

As shown in fig. 8, when a line has a permanent fault, the transient impedance at the fault point is set to be Z, which is much smaller than the load impedance Z_fhCapacitor pass load impedance Z_fhAnd the fault point transition impedance Z is discharged from the phase A to the phase B, and the total impedance of the capacitor discharge loop is small because the fault does not disappear, namely: the voltage attenuation is fast and the current is large.

The time for the absolute value of the pick-and-place voltage to drop from 281V to 50V is the voltage mutation time, and the time for the absolute value of the pick-and-place current to be larger than 20A is the current mutation time. From the viewpoint of capacitance capacity, the capacitance is preferably 2000 μ F. When the capacitance is 2000 muF, the maximum value of the permanent fault voltage mutation time is 0.0205s, and the minimum value of the transient fault voltage mutation time is 0.0432 s. The minimum value of the permanent fault current mutation time is 0.0052s, and the maximum value of the transient fault current mutation time is 0.0003 s.

Thus, as shown in fig. 9, a permanent fault identification criterion can be constructed: the sudden change time of the capacitor voltage is smaller than a first set time threshold or the sudden change time of the capacitor current is larger than a second set time threshold. The sudden change time of the capacitor voltage refers to the time taken by the capacitor voltage to decay from a first set voltage value to a second set voltage value, and the sudden change time of the capacitor current refers to the time taken by the absolute value of the capacitor current to be larger than a set current value. And when the capacitor voltage is smaller than the first set voltage value, delaying the falling edge (or the rising edge) of the third set time threshold edge for confirmation. The first set voltage value is 281V, the second set voltage value is 50V, the set current value is 20A, the first set time threshold value is 30ms, the second set time threshold value is 4ms, and the third set time threshold value is 1 ms. The set voltage value, the set current value, and each set time threshold value are values determined from simulation analysis and are not set.

And when the permanent fault identification criterion is met, judging that the line has a permanent fault, otherwise, judging that the line has a transient fault.

Then, the reclosing is locked when a permanent fault occurs in the line, and the reclosing is opened when a transient fault occurs in the line. The control logic of the closing reclosure is shown in fig. 10.

Aiming at the three-phase short-circuit fault with the symmetrical fault type:

when the fault is a symmetrical three-phase short-circuit fault, capacitors are put into phase-to-phase circuits corresponding to any two phases, namely capacitors are put into phase-to-phase circuits of the A phase and the B phase, capacitors are put into phase-to-phase circuits of the B phase and the C phase, and capacitors are put into phase-to-phase circuits of the A phase and the C phase. In this embodiment, the minimum value of the three inter-phase voltages is found, and a capacitor is put into the inter-phase loop of the two phases corresponding to the minimum inter-phase voltage, for example: and if the interphase voltage of the A phase and the B phase is minimum, putting a capacitor into an interphase loop of the A phase and the B phase.

As shown in fig. 11, when a transient fault occurs in the line, the capacitorThe impedance of the discharge loop being the load impedance Z_fhAnd line impedance Z_LAnd (4) summing. As shown in fig. 12, when a line has a permanent fault, the impedance of the capacitor discharge circuit is only the line impedance from the head end of the line to the point of fault. It can be seen that the impedance of the capacitor discharge circuit at the time of the permanent fault is much smaller than that at the time of the transient fault, that is, the capacitor discharge current at the time of the permanent fault is much larger than that at the time of the transient fault.

Likewise, as shown in fig. 9, a permanent fault identification criterion may be constructed: the sudden change time of the capacitor voltage is smaller than a first set time threshold or the sudden change time of the capacitor current is larger than a second set time threshold. The sudden change time of the capacitor voltage refers to the time taken by the capacitor voltage to decay from a first set voltage value to a second set voltage value, and the sudden change time of the capacitor current refers to the time taken by the absolute value of the capacitor current to be larger than a set current value. And when the capacitor voltage is smaller than the first set voltage value, delaying the falling edge (or the rising edge) of the third set time threshold edge for confirmation. The first set voltage value is 281V, the second set voltage value is 50V, the set current value is 20A, the first set time threshold value is 30ms, the second set time threshold value is 4ms, and the third set time threshold value is 1 ms. The set voltage value, the set current value, and each set time threshold value are values determined from simulation analysis and are not set.

It should be noted that the distribution line adaptive reclosing controller in fig. 1 is only one specific circuit for implementing the distribution line adaptive reclosing method, but the method for implementing the distribution line adaptive reclosing is not limited to the circuit configuration.

The embodiment of the self-adaptive reclosing method of the distribution line comprises the following steps:

the embodiment provides a distribution line self-adaptive reclosing method, which comprises a reclosing strategy aiming at an asymmetric interphase short-circuit fault and/or a reclosing strategy aiming at a symmetric three-phase short-circuit fault. Since two reclosing strategies have been described in detail in the above embodiment of the distribution line adaptive reclosing control device, they are not described herein again.

The embodiment of the method for identifying the fault property of the distribution line comprises the following steps:

the embodiment provides a distribution line fault property identification method, which comprises a fault property identification strategy aiming at an asymmetric interphase short-circuit fault of a fault type and/or a fault property identification strategy aiming at a three-phase short-circuit fault of a symmetric fault type:

the fault property identification strategy aiming at the asymmetric interphase short circuit fault with the fault type comprises the following steps:

(2) And detecting the capacitance voltage and/or the capacitance current after the capacitor is put into use, judging that the line has a permanent fault when the capacitance voltage and/or the capacitance current meet the permanent fault identification criterion, and otherwise, judging that the line has an instantaneous fault.

The fault property identification strategy for the three-phase short-circuit fault with the symmetrical fault type comprises the following steps:

2) And detecting the capacitance voltage and/or the capacitance current after the capacitor is put into use, judging that the line has a permanent fault when the capacitance voltage and/or the capacitance current meet the permanent fault identification criterion, and otherwise, judging that the line has an instantaneous fault.

The distribution line fault property identification method can be used as a part of a distribution line self-adaptive reclosing method, and after the distribution line fault property identification method identifies the fault property (namely permanent fault or transient fault), reclosing control is carried out according to a reclosing mode corresponding to the permanent fault or the transient fault. Since the distribution line fault property identification method is described in detail in the above embodiment of the distribution line adaptive reclosing method, it is not specifically described here.

Distribution lines fault nature identification device embodiment:

the present embodiment provides a distribution line fault property identification apparatus, a circuit structure of the apparatus is the same as a structure of a distribution line adaptive reclosing control apparatus in an embodiment of the distribution line adaptive reclosing control apparatus, and a difference is that an operation strategy of the apparatus is a distribution line fault property identification method.

Claims

1. A distribution line self-adaptive reclosing method is characterized by comprising the following steps:

2. The distribution line adaptive reclosing method according to claim 1, wherein the permanent fault identification criteria comprises: the sudden change time of the capacitor voltage is smaller than a first set time threshold or the sudden change time of the capacitor current is larger than a second set time threshold; the sudden change time of the capacitor voltage refers to the time taken by the capacitor voltage to decay from a first set voltage value to a second set voltage value, and the sudden change time of the capacitor current refers to the time taken by the absolute value of the capacitor current to be larger than a set current value.

3. The distribution line adaptive reclosing method according to claim 2, wherein the first set voltage value is 281V, the second set voltage value is 50V, and the set current value is 20A.

4. The distribution line adaptive reclosing method according to any one of claims 1 to 3, wherein when a symmetrical three-phase short circuit fault occurs, a capacitor is put into the inter-phase loop of two phases corresponding to the minimum inter-phase voltage.

5. A distribution line fault property identification method is characterized by comprising the following steps:

6. The distribution line fault nature identification method of claim 5, wherein the permanent fault identification criteria comprises: the sudden change time of the capacitor voltage is smaller than a first set time threshold or the sudden change time of the capacitor current is larger than a second set time threshold; the sudden change time of the capacitor voltage refers to the time taken by the capacitor voltage to decay from a first set voltage value to a second set voltage value, and the sudden change time of the capacitor current refers to the time taken by the absolute value of the capacitor current to be larger than a set current value.

7. The distribution line fault property identification method of claim 6, wherein the first set voltage value has a value range of 281V, the second set voltage value has a value range of 50V, and the set current value has a value range of 20A.

8. The distribution line fault nature recognition method of any of claims 5-7, wherein, if a symmetrical three-phase short circuit fault occurs, the capacitor is switched into the interphase circuit of the two phases corresponding to the minimum interphase voltage.

9. The distribution line self-adaptive reclosing control device is characterized by comprising a capacitor, a voltage detection module and/or a current detection module, wherein the capacitor is used for being put into any two corresponding phase-to-phase loops of a line, the voltage detection module is used for detecting the voltage of the capacitor, the current detection module is used for detecting the current of the capacitor, the main control unit is connected with the voltage detection module and/or the current detection module in a sampling mode, a communication port is arranged at the main control unit, the communication port is used for being in communication connection with a feeder terminal, and the main control unit is used for: receiving fault type information sent by a feeder terminal, and putting capacitors into interphase loops corresponding to two phases with faults if the asymmetric interphase short circuit faults occur; if a symmetrical three-phase short circuit fault occurs, putting capacitors into phase-to-phase loops corresponding to any two phases; receiving the capacitor voltage and/or the capacitor current sent by the voltage detection module and/or the current detection module, and judging whether the capacitor voltage and/or the capacitor current meet the permanent fault identification criterion; and if so, judging that the line has a permanent fault, otherwise, judging that the line has a transient fault, and sending the information of the permanent fault or the transient fault to the feeder line terminal for locking the reclosure when the line has the permanent fault and opening the reclosure when the line has the transient fault.

10. The distribution line fault property identification device is characterized by comprising a capacitor, a voltage detection module and/or a current detection module, wherein the capacitor is used for being input into any two phase-to-phase loops of a line, the voltage detection module is used for detecting the voltage of the capacitor, the current detection module is used for detecting the current of the capacitor, the main control unit is connected with the voltage detection module and/or the current detection module in a sampling mode, a communication port is arranged on the main control unit and is used for being in communication connection with a feeder terminal, and the main control unit is used for: receiving fault type information sent by a feeder terminal, and putting capacitors into interphase loops corresponding to two phases with faults if the asymmetric interphase short circuit faults occur; if a symmetrical three-phase short circuit fault occurs, putting capacitors into phase-to-phase loops corresponding to any two phases; receiving the capacitor voltage and/or the capacitor current sent by the voltage detection module and/or the current detection module, and judging whether the capacitor voltage and/or the capacitor current meet the permanent fault identification criterion; if so, judging that the line has a permanent fault, otherwise, judging that the line has a transient fault.