CN113381389B

CN113381389B - Self-adaptive comprehensive distributed feeder automation method

Info

Publication number: CN113381389B
Application number: CN202110068927.9A
Authority: CN
Inventors: 卜权; 叶丹; 孙侃
Original assignee: Jiayuan Technology Co Ltd
Current assignee: Jiayuan Technology Co Ltd
Priority date: 2021-01-19
Filing date: 2021-01-19
Publication date: 2022-12-27
Anticipated expiration: 2041-01-19
Also published as: CN113381389A

Abstract

The invention provides a self-adaptive integrated distributed feeder automation method, which judges whether the fault is an overcurrent and overvoltage fault or not by calculating a voltage and current effective value, comparing the voltage and current effective value with a voltage and current threshold value and comparing with overcurrent and overvoltage time, and judges whether the fault is a low-current ground fault or not by calculating a correlation coefficient by using a correlation analysis method by using current and voltage derivatives. And detecting fault current according to the FTU, positioning whether the main line is short-circuited or the branch is short-circuited, and processing the short-circuit fault of the main line, the short-circuit fault of the user branch and the low-current grounding fault of the main line under the condition that the terminal is electrified. According to the invention, through a 'non-voltage switching-off and incoming call delay switching-on' mode, a short circuit/grounding fault detection technology and a fault path priority processing control strategy are combined, and secondary switching-on of a transformer substation outgoing switch is matched, so that fault positioning and isolation self-adaption of a multi-branch multi-connection distribution network frame are realized, a fault section is isolated by primary switching-on, and power supply of a non-fault section is recovered by secondary switching-on.

Description

Self-adaptive comprehensive distributed feeder automation method

Technical Field

The invention relates to the technical field of feeder automation measurement and control terminals, in particular to a self-adaptive comprehensive distributed feeder automation method.

Background

Feeder automation is one of the cores of distribution automation construction, and in-situ feeder automation can greatly shorten the time for fault detection, fault isolation and power restoration of a non-fault area of a distribution line. Among the Feeder Automation schemes for distribution network Automation, distributed Feeder Automation (FA) is currently the most rapid local Feeder Automation scheme.

Currently, a voltage-time type feeder automation scheme is used more. The scheme realizes the on-site feeder automation by matching the working characteristics of 'non-voltage switching-off and incoming call delay switching-on' of the switch with the secondary switching-on of the outgoing line switch of the transformer substation. And the primary closing is used for isolating a fault section, and the secondary closing is used for recovering the power supply of a non-fault section. However, the scheme treats transient faults occurring on the feeder line according to the time sequence of permanent faults, and cannot recover power supply in a short time. The scheme can only process the short-circuit fault of the main line, and can not process the short-circuit fault of the user branch and the ground fault of the main line.

The probability of transient faults on the line is high, even reaches 70% -80% of the line faults, and therefore a voltage-current time type feeder automation scheme is led out. According to the scheme, the judgment of fault current and grounding current is added on the basis of a voltage time type scheme, the power-on X time limit switching-on is followed, the residual voltage locking switching-on is detected in the X time limit, and the voltage loss in the Y time limit after the switching-on and the basic logic of the fault current locking switching-on are detected. Meanwhile, the logic that the fault current is not detected to block the brake is provided within Y time limit after the brake is closed, so that the fault isolation process is accelerated. If the switch adopts a spring operation mechanism, a power-off delay switch-off (matched with the quick reclosing time of the outgoing switch of the transformer substation) can be added to quickly isolate instantaneous faults. But this solution does not address fault location and isolation of the multi-branch multi-contact distribution grid.

Disclosure of Invention

The technical problem to be solved by the present invention is to solve at least one aspect of the above prior art, and provide a self-adaptive integrated distributed feeder automation method, which realizes the whole process of fault location, fault isolation and power restoration.

The technical scheme adopted by the invention is as follows.

The invention provides a self-adaptive comprehensive distributed feeder automation method, which comprises the following steps: sampling a line by using a Feeder Terminal Unit (FTU) to obtain a line voltage value and a line current value, and calculating effective values of the voltage value and the current value; respectively comparing the effective values of the voltage value and the current value with corresponding threshold values to determine whether a line has a fault; when the effective value of the voltage value or the current value is larger than the corresponding threshold value, judging that the line has a fault; otherwise, judging that no fault exists in the line;

if the FTU judges that the line has a fault, the FTU executes the following operations under the condition that the terminal is electrified:

judging the condition that the time of overcurrent and overvoltage is greater than a threshold value as a short-circuit fault, and positioning whether the main line short-circuit fault or the user branch short-circuit fault occurs according to whether the line with the overcurrent and overvoltage is the main line or the user branch; calculating a correlation coefficient by using a correlation analysis method based on the current and voltage derivatives, and judging whether a main line low-current ground fault exists or not;

and respectively carrying out corresponding fault processing according to a preset fault processing strategy aiming at the short-circuit fault of the main line, the short-circuit fault of the user branch and the small-current grounding fault of the main line.

Further, still include: a residual voltage module is arranged on a distribution feeder terminal FTU and used for collecting residual voltage; if the line is judged to have a fault, a residual voltage module is adopted to complete reverse locking under the condition that the FTU is power-off.

Still further, the logic for completing reverse blocking by the residual voltage module is as follows:

if the left side voltage is greater than the residual voltage fixed value, the left side voltage is less than the voltage fixed value and the right side voltage is less than the non-voltage fixed value, judging that left side residual voltage exists, and setting a left side residual voltage mark and storing the left side residual voltage mark; if the conditions that the right side voltage is greater than the residual voltage fixed value, the right side voltage is less than the voltage fixed value and the left side voltage is less than the non-voltage fixed value are met, judging that the right side residual voltage exists, and setting a right side residual voltage mark and storing the right side residual voltage mark; after the distribution feeder terminal FTU is normally powered on, the residual voltage module sends the left residual voltage mark or the right residual voltage mark to the host CPU through a communication line, and the host CPU obtains power-on and switch-off logic on the opposite side according to the residual voltage mark locking.

Further, the specific method for judging whether the small current ground fault is caused by calculating the correlation coefficient by using the current and voltage derivatives and using a correlation analysis method is as follows:

the degree of linear similarity of the N-point lengths (i.e., N sampling points) of the two signal waveforms x, y is expressed by a correlation coefficient ρ (x, y) as:

judging whether the fault is a low-current ground fault and realizing the low-current ground fault line selection criterion as follows:

judging a health full line;

judging the bus low-current ground fault;

wherein k =1,2 _0k Current value, u, of the k-th point representing zero sequence current ₀ Indicating bus zero sequence voltage, K ₁ Is a first threshold value, K ₂ Is the second threshold.

Further, the fault handling strategy for a short-circuit fault of the main line comprises the following steps:

when a permanent fault occurs between two intelligent load section switches on the main line;

the circuit breaker of the main line detects overcurrent protection tripping, and the intelligent load section switches of the main line and the branches connected with the main line are all tripped in a voltage loss manner;

the circuit breaker of the main line is subjected to first reclosing after a first set time interval;

the line intelligent load section switch of the main line on the left side of the fault is switched on sequentially after a first set time interval; one side of an intelligent load section switch on a branch line connected with the main line has pressure but no fault current memory, and is switched on after a second set long delay time interval;

at the moment of switching on of the intelligent load section switch adjacent to the left side of the fault, the intelligent load section switch adjacent to the right side of the fault is powered on for a short time;

when the left adjacent intelligent load section switch with the fault trips again, the left adjacent intelligent load section switch with the fault is switched off and then is switched on in a locking mode; when the intelligent load section switch adjacent to the right side of the fault loses voltage within a set time limit, the intelligent load section switch adjacent to the right side of the fault is reversely locked and switched on;

and the other intelligent load section switches on the left adjacent and the right adjacent to the main line and the branch line intelligent load section switches connected with the main line are sequentially switched on in a delayed mode.

Further, the fault handling strategy for the user branch short circuit fault comprises the following steps: when the line behind the user boundary switch on the user branch is short-circuited, the user boundary switch on the left side of the fault and the intelligent load section switch on the main line on the left side of the node intersected with the main line of the branch have fault current memory,

when the breaker trips, the intelligent load section switches on the main line and the branches lose voltage and are switched off, and nodes of user boundaries adjacent to the left of the fault are switched off after no voltage and no current exist;

and after the circuit breaker of the main line is reclosed for the first time after a set time interval, the intelligent load section switches on the main line and the branch are sequentially closed.

Further, the fault handling strategy for low-current ground fault line selection includes single-phase ground fault line selection and single-phase ground fault location isolation, and the single-line ground fault line selection strategy includes: meanwhile, the condition that a newly generated single-phase grounding fault exists, the single-phase grounding characteristic direction is determined, and the single-phase grounding line selection is input is met, and the tripping operation is carried out after the grounding line selection tripping time interval;

after a set interval time after tripping, reclosing is carried out when the following three conditions are met simultaneously:

the first condition is that: single-phase grounding line selection input;

the second condition is that: single-phase grounding characteristic direction memory;

the third condition is that: one side has pressure and the other side has no pressure, the switch is at a separated position and has no flow, and simultaneously any one of the following conditions is not satisfied: a locking closing switch-in or a manual locking closing switch-in, a remote tripping locking closing switch-in, a forward locking and a reverse locking;

the single-phase earth fault positioning and isolating strategy comprises the following steps: after reclosing is carried out by adopting a single-wire grounding fault line selection strategy, tripping and forward locking are carried out when the following conditions are met:

and if the single-phase earth fault still exists after the switch is closed for a set time interval, tripping and locking in the positive direction.

Further, the fault handling strategy for a main line low current ground fault comprises the following steps: the intelligent load section switch which is positioned on the main line and connected with the main line breaker is a head-end feeder line terminal unit, and a line behind the intelligent load section switch on the user branch has a small-current grounding short circuit, so that the intelligent load section switch connected to the main line breaker on the left side of a fault has fault current memory;

the head end feeder line terminal unit trips after a delay protection time interval;

the head end feeder line terminal unit is reclosed after a set time interval;

intelligent load section switch connected with head end feeder line terminal unit on fault left side

Sequentially powering and switching on after a first set time limit X time limit; other intelligent load section switches of the main line have no fault current memory, the intelligent load section switches are switched on after a second set time interval, zero sequence voltage mutation occurs in a set time limit after the intelligent load section switches on the left adjacent to the fault, and the intelligent load section switches on the left adjacent to the fault are switched off and switched on in a locking mode; at the moment that the intelligent load section switch adjacent to the fault left is switched on, the intelligent load section switch adjacent to the fault right is switched on; after the intelligent load section switch adjacent to the left side of the fault is subjected to brake-off voltage loss, the intelligent load section switch adjacent to the right side of the fault is reversely locked and closed;

and other intelligent load section switches of the main line are sequentially switched on to recover power supply.

Further, the logic of forward latching in the method is as follows: tripping and positively latching when the following two conditions are met simultaneously: the first condition is as follows: switching on a switch;

and (2) carrying out a second condition: double-sided no voltage and no current or single-phase earth fault.

Further, the logic of the reverse latch is: when the last-stage switch is switched on and supplies power, the switch detects the process of no voltage, residual voltage and no voltage on one side of the switch in X time, and accordingly the switch on fault of the last-stage switch can be judged, the FTU of the last stage is provided with a forward locking mark, the FTU of the switch is switched into reverse locking, and the locking switch is switched on when the locking switch supplies power reversely; when the FTU of the reverse locking is in forward power transmission, the reverse locking mark can be automatically reset after time delay.

The invention has the following beneficial technical effects:

the invention provides a self-adaptive comprehensive distributed feeder automation method, which realizes fault location and isolation self-adaptation of a multi-branch multi-connection distribution network frame by combining a non-voltage switching-off and incoming call delay switching-on mode, a short circuit/grounding fault detection technology and a fault path priority processing control strategy and matching with secondary switching-on of a substation outgoing switch, wherein the primary switching-on isolates a fault section, and the secondary switching-on restores power supply of a non-fault section.

Drawings

FIG. 1 is a logic diagram of single phase ground fault location in an embodiment of an adaptive in-situ feeder automation method;

FIG. 2 is a logic diagram of single phase ground fault line selection in an embodiment of an adaptive in-situ feeder automation method;

FIG. 3 is a diagram of forward latching logic in an embodiment of an adaptive in-place feeder automation method;

FIG. 4 is a diagram of reverse blocking logic in an embodiment of an adaptive in-situ feeder automation method;

FIG. 5 is a trunk short-circuit fault diagram of one embodiment of the present application;

FIG. 6 is a diagram of circuit breaker CB tripped, FS1-FS6 opening;

fig. 7 is a diagram of the circuit breaker CB reclosing for the first time after 2 s;

FIG. 8 is an FS1 time-delay 7s closing diagram;

FIG. 9 is a diagram of FS2 closing with a delay of 7s and FS4 closing with a start of a long delay of 7+ 50s;

fig. 10 is a diagram of the circuit breaker CB being tripped again, FS2 being opened and closed by latching, and FS3 being closed by reverse latching;

fig. 11 is a diagram of circuit breaker CB twice reclosing, FS1, FS4, FS5, FS6 sequentially delaying closing;

FIG. 12 is a diagram of a subscriber branch short circuit fault in accordance with one embodiment of the present application;

FIG. 13 is a main line ground (low current ground) fault diagram of one embodiment of the present application;

FIG. 14 is a FS1 time delay protection trip (20 s) diagram of an embodiment of the present application;

fig. 15 is a diagram of the FS1 reclosing after a delay of 2s according to an embodiment of the present application;

fig. 16 is a delayed 7S switching-on diagram of FS2 according to S time after FS4 and FS5 are powered on according to an embodiment of the present application;

FIG. 17 is a diagram of FS5 direct opening and closing with latching and FS6 reverse closing with latching according to an embodiment of the present application;

fig. 18 is a diagram of sequentially closing and recovering power supplies of FS2 and FS3 according to an embodiment of the present application;

FIG. 19 is a software layout of a residual voltage module according to an embodiment of the present application;

FIG. 20 is a schematic flow chart diagram of a method according to an embodiment of the present application.

Detailed Description

The objects and functions of the present invention and methods for accomplishing the same will be apparent by reference to the exemplary embodiments. However, the present invention is not limited to the exemplary embodiments disclosed below; it can be implemented in various forms. The description is merely exemplary in nature and is intended to provide a thorough understanding of the present invention by those of ordinary skill in the relevant art.

First embodiment, the present embodiment provides an adaptive generalized distributed feeder automation method, and a flow diagram is shown in fig. 20, including the following steps: sampling a line by using a distribution feeder terminal FTU to obtain a line voltage value and a line current value, and calculating effective values of the voltage value and the current value; comparing the effective value with a threshold value to determine whether a line has a fault;

and respectively carrying out corresponding fault processing according to a preset fault processing strategy aiming at the short-circuit fault of the main line, the short-circuit fault of the user branch and the low-current grounding fault of the main line.

In the embodiment of the invention, 20 sampling points are selected from 100 points of each cycle, and the sampling points are calculated every 5 points. The sample interrupt calls are counted every 1 millisecond. The calculation process of the novel recursion Fourier algorithm is as follows:

step 1: firstly, differential filtering is carried out to remove direct current signals, and y (n) = x (n) -x (n-1) is obtained;

step 2, the amplitude-frequency response of the first-order difference of the above formula is

The phase response is

It can be derived that the harmonics of y (n) are the amplitudes of the harmonics of x (n)

Multiple, initial phase

k represents the harmonic order and N represents the number of samples per cycle.

And step 3: recursive fourier transform equation

Where N represents the current sample point, k represents the harmonic order, and N represents the number of sample points per cycle.

And 4, step 4: for a pure AC signal, it is now assumed that y (n) is a pure AC signal.

The initial phase has

The phase difference, so the differential recursive fourier transform equation can be defined as:

factor of coefficient

Then real part Re [ X ] _k (n)]Expressed as:

assuming that the amplitude of the AC signal varies linearly within a period, i.e. it varies linearly

And 5: the imaginary coefficient factor can be obtained by the same way as

Imaginary part Im [ X [ ] _k (n)]Expressed as:

the effective values of the current or voltage are: | Re [ X |) _k (n)]+Im[X _k (n)]|；

And comparing the effective value of the voltage and the current measured by the FTU with a threshold value, and judging that a fault exists when the effective value of the voltage or the current is greater than the corresponding threshold value.

The above formula exists on the premise that the hardware acquisition system is a linear time-invariant system.

In the embodiment, a novel recursive fourier algorithm is adopted to calculate the real part and the imaginary part of the protection measurement voltage current value, so that the voltage current effective value, namely the modulus of the real part and the imaginary part of the voltage current is calculated, and whether the overcurrent and overvoltage fault occurs or not is judged according to the voltage current threshold and the time. The fault type is judged through the effective value of the voltage and the current calculated by the Fourier algorithm, whether the fault is an earth fault or an over-current and over-voltage fault is judged, whether the main line short circuit or the branch short circuit is positioned according to the fault current detected by the FTU, and under the condition that the terminal is electrified, the main line short circuit fault processing, the user branch short circuit fault processing and the main line grounding (low-current grounding) fault processing are carried out.

In this embodiment, the technical innovation point of the invention is that a correlation analysis method is adopted, and the judgment of the small-current ground fault is realized by calculating the correlation coefficient between the zero-sequence current of each outgoing line and the zero-sequence voltage derivative of the bus.

The degree of linear similarity of the N-point lengths of the two signal waveforms x, y is expressed by a correlation coefficient ρ (x, y)

If ρ (x, y) =1, then there is a positive linear relationship between the two quantities; if ρ (x, y) = -1, then a negative linear relationship exists between the two quantities; if ρ (x, y) =0, there is no correlation between the two quantities.

It is generally believed that: | ρ (x, y) | < 0.3, no correlation; less than or equal to 0.3 and less than 0.5 of rho (x, y) and low degree correlation; 0.5 or more | rho (x, y) | < 0.8, and moderate correlation; and | rho (x, y) | is more than or equal to 0.8 and less than 1, and the correlation is high.

The actual criterion of the ungrounded neutral system is taken as

Judging a health full line;

judging the bus low-current ground fault.

Wherein k =1, 2. i all right angle _0k Current value, u, at the kth point representing zero sequence current ₀ And representing the zero sequence voltage of the bus. In the embodiment of the application of the invention, when the zero sequence voltage has a sudden change, namely the voltage and current correlation is the best, 3 samples of the voltage and current are respectively taken at the moment, and 3 samples are calculated

And (3) judging the sampling points to be 10 in each sampling point, wherein the sampling points are 100 sampling points in one cycle, and n represents that the sampling points are judged to be a fault line when more than or equal to 2 times in 3 samples.

In the present embodiment, the feeder automation main trunk short-circuit fault processing scenarios shown in fig. 5 to 11 are performed, and the adaptive integrated feeder automation fault isolation process is as follows. And the CB is a 10KV feeder line outgoing breaker with time limit protection and secondary reclosing functions. FS1-FS6 are UIT type intelligent load section switches; LSW1, LSW2: the YS 1-YS 2 are user demarcation switches.

(1) A permanent fault occurs between FS2 and FS3, and FS1, FS2 detect the fault current and memorize it (see fig. 5).

(2) The circuit breaker CB detects overcurrent protection tripping, and FS1-FS6 lose voltage and are opened (shown in figure 6).

(3) The circuit breaker CB performs a first reclosing after 2s (see fig. 7).

(4) And (3) one side of the FS1 has pressure and has fault current memory, and the time is delayed for 7s to switch on (the 7s is X time limit, and the fault memory device can delay the X time limit to switch on after being electrified). The X time limit refers to the time of delayed closing after power is applied (as shown in fig. 8).

(5) And (3) memorizing the pressed and fault current at one side of FS2, delaying switching on for 7S (as shown in figure 9), memorizing the pressed and fault current at one side of FS4, starting long delay of 7+50s (delaying switching on according to S time after the power is obtained without the fault memory) (waiting for the completion of fault line isolation, and estimating according to the longest time, wherein at most four switches of the main line consider that one-stage switching is provided with four switches).

(6) Due to the permanent fault, the circuit breaker CB trips again, and after FS2 is switched on, the voltage is lost within the Y time limit, and at this time, FS2 is switched off and switched on in a locking manner (as shown in fig. 10). At the moment of switching on the FS2, the FS3 is electrified in a short time; after FS2 is switched off, FS3 is decompressed within X time limit, and at the moment, FS3 is reversely locked and switched on. The Y time limit refers to the time for judging the fault by the electric switch-on.

(7) The circuit breaker CB is closed for the second time, and FS1, FS4, FS5, and FS6 are sequentially closed in a delayed manner (as shown in fig. 11).

Executing the scenario of processing short-circuit fault of feeder automation user branch as shown in fig. 12, the adaptive generalized feeder automation fault isolation process is as follows:

(1) After YS1, a short-circuit fault occurs, and FS1, FS4, YS1 have fault current memory.

(2) And the breaker CB trips due to overcurrent protection, the FS1-FS6 is subjected to voltage loss and brake separation, and the YS1 is subjected to no-voltage no-current brake separation.

(3) The circuit breaker CB recloses for the first time after 15 s.

(4) FS1-FS6 are switched on in a delayed mode in sequence.

Performing the feeder automation main line ground fault (low current ground) processing scenario as shown in fig. 13 to 18, the adaptive integrated feeder automation fault isolation process is as follows:

(1) FS1 is set to be in a line selection mode before installation, and other switches are in a segment selection mode. The line selection mode refers to that a head-end Feeder Terminal Unit (FTU) alarms and trips, and the section selection mode refers to that the other non-head-end FTUs only alarms.

(2) And a single-phase earth fault occurs after the FS5, and the FS1, the FS4 and the FS5 select the earth fault at the rear end of the earth fault according to a transient algorithm and have fault memory. (see fig. 13)

(3) FS1 time delay protection trips (20 s). (see fig. 14)

(4) FS1 recloses after a delay of 2 s. (see fig. 15)

(5) One side of the FS4 and the FS5 has pressure and has fault memory, the time is delayed for 7S (X time limit) to switch on after power is obtained, the FS2 has no fault memory, and the switch on is delayed according to S time. (as in FIG. 16)

(6) And after the FS5 is switched on, zero sequence voltage mutation occurs in the Y time limit, and the FS5 is directly switched off and switched on in a locking manner. At the moment of switching on the FS5, switching on the FS6 in a short time by X time limit delay; after FS5 is switched off, FS6 is decompressed within X time limit, and FS6 is closed in a reverse locking mode. (as in FIG. 17)

(7) FS2 and FS3 are sequentially switched on to recover power supply. (as in FIG. 18)

In a second embodiment, on the basis of the first embodiment, the adaptive generalized distributed feeder automation method provided in this embodiment further includes: a residual voltage module is arranged on a power distribution feeder terminal FTU and used for collecting residual voltage; and if the line is judged to have a fault, the residual voltage module is adopted to complete reverse locking under the condition that the FTU is out of power.

After the terminal is powered off, the residual voltage module supplements the self-adaptive comprehensive distributed feeder automation technology, a residual voltage module is added to a traditional distribution feeder terminal FTU for collecting residual voltage, and the residual voltage module can inform a main Central Processing Unit (CPU) of the FTU after the device is normally powered on, so that logic of reverse locking is completed (a logic schematic diagram is shown in fig. 19).

And when the voltage at the left end detected by the FTU is greater than a residual voltage fixed value and less than a voltage fixed value, and the voltage at the right end is less than a non-voltage fixed value, judging that the voltage is left residual voltage, and setting a left residual voltage mark and storing the left residual voltage mark. And when the voltage at the right end is greater than the residual voltage fixed value and less than the voltage fixed value, and the voltage at the left end is less than the non-voltage fixed value, judging the voltage at the right end to be the residual voltage at the right side, and setting and storing a residual voltage mark at the right side. And after the terminal is normally powered on, the residual voltage module sends the residual voltage mark to the main CPU through the serial port. And the main CPU locks the opposite side according to the residual voltage mark to obtain electric switching-on logic.

The residual voltage module has an energy storage function, can store the instantaneous incoming call on the line after the terminal is powered off, and can provide short-time operation for the residual voltage module. The residual voltage module is provided with an expanded serial port, and after the terminal is normally powered on, the residual voltage module can send the residual voltage information to the main CPU through the serial port so that the main CPU can add the residual voltage information into logic judgment. The design scheme of residual voltage module software is shown in FIG. 15, in which U _L Left side voltage; u shape _R The right voltage.

The fault handling strategy for the small-current ground fault line selection comprises single-phase ground fault line selection and single-phase ground fault positioning isolation, and the single-line ground fault line selection strategy (as shown in fig. 2) comprises the following steps:

meanwhile, the condition that a single-phase earth fault occurs newly, the single-phase earth characteristic direction is determined, and the single-phase earth line selection is input is met, and then tripping is carried out after the time interval of the earth line selection tripping;

after the set interval time after tripping, reclosing is carried out when the following three conditions are met simultaneously:

the first condition is that: single-phase grounding line selection input;

the single-phase earth fault location isolation strategy (as shown in fig. 1) comprises: after reclosing is carried out by adopting a single-wire grounding fault line selection strategy, tripping and forward locking are carried out when the following conditions are met:

and if the single-phase earth fault still exists after the switch is switched on for a set time interval, tripping and locking in the forward direction.

An adaptive in-place feeder automation forward latching logic diagram, as shown in FIG. 3. The logic of the forward locking in the method is as follows: tripping and positively latching when the following two conditions are met simultaneously: the first condition is as follows: switching on a switch; and a second condition: there is no voltage and no current on both sides or a single phase earth fault.

An adaptive in-place feeder automation reverse latching logic diagram is shown in fig. 4. When the last-stage switch is switched on and supplies power, the switch detects the process of 'no voltage-residual voltage-no voltage' of one side of the switch in X time, and accordingly the switch on fault of the last-stage switch can be judged (the FTU of the last stage is provided with a forward locking mark), the FTU of the switch is switched into 'reverse locking', and the locking switch is switched on when the locking switch supplies power reversely; when the FTU of the reverse locking is in forward power transmission, the reverse locking mark can be automatically reset after time delay.

The voltage and current values of FTU cycle sampling data are used for calculating the real part and the imaginary part of the protection measurement voltage and current value by adopting a novel recursive Fourier algorithm, so that the voltage and current effective value is calculated, whether the fault is an overcurrent and overvoltage fault (namely a short-circuit fault) is judged by comparing the voltage and current effective value with the voltage and current threshold value and comparing with the overcurrent and overvoltage time, the correlation coefficient is calculated by using a correlation analysis method by using current and voltage derivatives, and whether the fault is a low-current grounding fault is judged. Detecting fault current according to the FTU, positioning whether a main line is short-circuited or a branch is short-circuited, and processing the main line short-circuited fault, the user branch short-circuited fault and the main line grounding (low current grounding) fault under the condition that a terminal is electrified; and under the condition that the terminal is power-off, the residual voltage module is adopted to complete reverse locking.

The invention provides a self-adaptive comprehensive distributed feeder automation method. The self-adaptive comprehensive feeder automation realizes the fault location and isolation self-adaptation of the multi-branch multi-network distribution network frame by combining a non-voltage switching-off and incoming call delay switching-on mode, a short circuit/ground fault detection technology and a fault path priority processing control strategy and matching with the secondary switching-on of an outlet switch of a transformer substation, and the secondary switching-on restores the power supply of a non-fault section during the primary switching-on isolation fault interval. And (3) realizing small-current ground fault line selection by adopting a correlation analysis method and calculating a correlation coefficient between the zero-sequence current of each outgoing line and the zero-sequence voltage derivative of the bus. Under the condition of overcurrent, overvoltage and zero voltage mutation, a novel recursive Fourier algorithm is adopted to calculate and protect the real part and the imaginary part of the measured voltage and current value, so that the effective value of the voltage and the current is calculated, and whether the fault occurs is judged according to the voltage and current threshold value and the time. After the terminal is powered off, a residual voltage module is added to a traditional power distribution feeder terminal FTU for collecting residual voltage, and a main Central Processing Unit (CPU) of the FTU can be informed after the device is normally powered on, so that the logic of reverse locking is completed.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While the present invention has been described with reference to the particular illustrative embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications, equivalent arrangements, and equivalents thereof, which may be made by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. An adaptive integrated distributed feeder automation method, comprising the steps of: sampling the line by using a power distribution feeder terminal FTU to obtain a line voltage value and a line current value, and calculating effective values of the voltage value and the current value; respectively comparing the effective values of the voltage value and the current value with corresponding threshold values to determine whether a line has a fault;

respectively carrying out corresponding fault processing according to a preset fault processing strategy aiming at a main line short-circuit fault, a user branch short-circuit fault and a main line low-current grounding fault;

the fault processing strategy aiming at the small current ground fault line selection comprises single-phase ground fault line selection and single-phase ground fault positioning isolation, and the single-phase ground fault line selection strategy comprises the following steps:

the first condition is that: single-phase grounding line selection input;

the third condition is that: one side has pressure and the other side has no pressure, the switch is at a separated position and has no flow, and simultaneously any one of the following conditions is not satisfied: a locking switch-on or a manual locking switch-on, a remote tripping locking switch-on, a forward locking and a reverse locking;

the single-phase earth fault positioning and isolating strategy comprises the following steps: after reclosing is carried out by adopting a single-phase earth fault line selection strategy, tripping and positive locking are carried out when the following conditions are met:

when the switch is switched on and still has single-phase earth fault after a set time interval, tripping and locking in the forward direction;

the logic for forward blocking is: tripping and positively latching when the following two conditions are met simultaneously:

the first condition is as follows: switching on a switch;

and a second condition: the two sides have no voltage and no current or have single-phase earth fault;

the logic of the reverse latch is: when the last-stage switch is switched on and supplies power, the switch detects the process of no voltage, residual voltage and no voltage on one side of the switch in X time, accordingly, the switch is judged to be switched on in fault, the FTU of the last stage is provided with a forward locking mark, the FTU of the switch is switched into reverse locking, and the locking switch is switched on when the locking switch supplies power in reverse direction; when the FTU of the reverse locking is in forward power transmission, the reverse locking mark can be automatically reset after time delay.

2. The adaptive integrated distributed feeder automation method of claim 1, further comprising: a residual voltage module is arranged on a distribution feeder terminal FTU and used for collecting residual voltage; if the line is judged to have a fault, a residual voltage module is adopted to complete reverse locking under the condition that the FTU is power-off.

3. The adaptive integrated distributed feeder automation method of claim 2, wherein the logic to complete the reverse blocking with the residual voltage module is as follows:

4. The adaptive integrated distributed feeder automation method of claim 1, wherein the correlation coefficient is calculated by using a correlation analysis method using current and voltage derivatives, and the specific method for determining whether the fault is a low-current ground fault is as follows:

the degree of linear similarity of the lengths of N points of the two signal waveforms x, y is expressed by a correlation coefficient ρ (x, y) as:

judging a health full line;

judging the bus low-current ground fault;

5. The adaptive integrated distributed feeder automation method of claim 1, wherein the fault handling strategy for a trunk short circuit fault comprises the steps of:

a breaker of a main line detects overcurrent protection tripping, and intelligent load section switches of the main line and a branch connected with the main line trip in a voltage loss manner;

the line intelligent load section switch of the main line on the left side of the fault is switched on after a first set time interval in sequence; one side of an intelligent load section switch on a branch line connected with the main line has pressure but no fault current memory, and is switched on after a second set long delay time interval;

when the intelligent load section switch adjacent to the left side of the fault trips again, the intelligent load section switch adjacent to the left side of the fault is switched off and then is switched on in a locking mode; the intelligent load section switch adjacent to the right side of the fault is under the voltage loss within the set time limit, and the intelligent load section switch adjacent to the right side of the fault is reversely locked and switched on at the moment;

6. The adaptive integrated distributed feeder automation method of claim 1, wherein the fault handling strategy for a subscriber branch short circuit fault comprises the steps of:

when a short circuit occurs on a line behind a user demarcation switch on a user branch, the user demarcation switch on the left side of a fault and an intelligent load section switch positioned on a main line on the left side of a node intersected with the main line and on the left side of the node intersected with the main line have fault current memory, and when a breaker trips, the intelligent load section switches on the main line and the branch are subjected to voltage loss and brake separation, and the node of the user demarcation adjacent to the left side of the fault is subjected to no voltage and no current and then is subjected to brake separation;

and after the circuit breaker of the main line is reclosed for the first time after a set time interval, the intelligent load section switches on the main line and the branches are sequentially closed.

7. The adaptive integrated distributed feeder automation method of claim 1, wherein the fault handling strategy for a main line low current ground fault comprises the steps of:

the intelligent load section switch which is positioned on the main line and connected with the main line circuit breaker is a head-end feeder line terminal unit, and a line behind the intelligent load section switch on the user branch has a small-current grounding short circuit, so that the intelligent load section switch connected to the main line circuit breaker on the left side of a fault has fault current memory;

the head end feeder line terminal unit recloses after a set time interval;

each intelligent load section switch connected with the head end feeder line terminal unit on the left side of the fault is sequentially powered on and is sequentially switched on after a first set time limit X; other intelligent load section switches of the main line have no fault current memory, the intelligent load section switches are switched on after a second set time interval, zero sequence voltage mutation occurs in a set time limit after the intelligent load section switch adjacent to the left side of the fault is switched on, and the intelligent load section switch adjacent to the left side of the fault is switched off and switched on in a locking mode; at the moment that the intelligent load section switch adjacent to the fault left is switched on, the intelligent load section switch adjacent to the fault right is switched on; after the intelligent load section switch adjacent to the left side of the fault is subjected to brake-off voltage loss, the intelligent load section switch adjacent to the right side of the fault is reversely locked and closed;