CN110794326A - Line selection method, device and system for short-circuit protection of power distribution system - Google Patents
Line selection method, device and system for short-circuit protection of power distribution system Download PDFInfo
- Publication number
- CN110794326A CN110794326A CN201910918105.8A CN201910918105A CN110794326A CN 110794326 A CN110794326 A CN 110794326A CN 201910918105 A CN201910918105 A CN 201910918105A CN 110794326 A CN110794326 A CN 110794326A
- Authority
- CN
- China
- Prior art keywords
- line
- current
- short
- distribution system
- power distribution
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000010187 selection method Methods 0.000 title claims abstract description 16
- 238000000034 method Methods 0.000 claims abstract description 26
- 230000009471 action Effects 0.000 claims abstract description 8
- 230000035772 mutation Effects 0.000 claims description 44
- 230000008859 change Effects 0.000 claims description 39
- 230000002159 abnormal effect Effects 0.000 claims description 12
- 230000000877 morphologic effect Effects 0.000 claims description 11
- 238000001514 detection method Methods 0.000 claims description 10
- 238000012545 processing Methods 0.000 claims description 6
- 238000004804 winding Methods 0.000 claims description 5
- 238000004364 calculation method Methods 0.000 claims description 4
- 230000003287 optical effect Effects 0.000 claims description 4
- 230000035945 sensitivity Effects 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 7
- 230000001052 transient effect Effects 0.000 description 6
- 244000020998 Acacia farnesiana Species 0.000 description 4
- 235000010643 Leucaena leucocephala Nutrition 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 230000007935 neutral effect Effects 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 238000005070 sampling Methods 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 238000004422 calculation algorithm Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000010891 electric arc Methods 0.000 description 2
- 230000003628 erosive effect Effects 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 230000033001 locomotion Effects 0.000 description 2
- 238000013178 mathematical model Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 206010000369 Accident Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 238000012549 training Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/04—Details with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned
- H02H3/042—Details with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned combined with means for locating the fault
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/22—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Locating Faults (AREA)
Abstract
The invention relates to a line selection method, a line selection device and a line selection system for short-circuit protection of a power distribution system, and belongs to the technical field of relay protection of power systems. The method mainly comprises a current signal and an arc light signal, wherein the two criterions are 'AND' operated to be exported, namely the arc light signal is used as a starting signal of the accurate short-circuit protection method of the power distribution system, the current signal is used as an action signal of the accurate short-circuit protection method of the power distribution system after certain time delay, namely the traditional direct 'AND' operation is converted into sequential control with certain time delay in the middle, the reliability of the protection method can be effectively improved, and the contradiction between accuracy and sensitivity is considered. Meanwhile, the line selection device and the line selection system for the short-circuit protection of the power distribution system are developed according to a line selection method.
Description
Technical Field
The invention relates to a line selection method, a line selection device and a line selection system for short-circuit protection of a power distribution system, and belongs to the technical field of relay protection of power systems.
Background
The urban distribution network mainly takes a switch cabinet and a cable as main parts, the generated faults are mostly permanent faults, and the single-phase grounding and phase-to-phase short circuit faults are easy to cause serious cable trench, switch cabinet and even transformer substation fire accidents after long-time operation. The arc fault has a certain randomness due to the reasons of unstable contact between electricity and a medium in the initial stage, unstable combustion of an arc, physical and chemical changes of the medium and the like of the earth fault current, and the characteristic that the fault current has nonlinear distortion is widely accepted by researchers.
DL/T872-: the fault line selection device can accurately select a fault branch, when a neutral point is grounded through an arc suppression coil, a variable frequency and traveling wave signal needs to be injected, namely the property of the ground fault cannot be judged, a permanent single-phase ground fault line cannot be cut off easily in time, a power supply cannot be separated in time when a person gets an electric shock, and a greater safety risk exists; when a neutral point is grounded through a small resistor, the fault current is large, the generation of intermittent arc grounding overvoltage can be inhibited, feeder zero sequence protection can smoothly act to enable a circuit to trip, but the action time is long (more than 3s), the circuit can cause great personal safety risk if the fault circuit cannot be timely cut off, a certain power supply bureau 10kV combined transformer (oil-immersed type) of a power grid company in south China in 5 and 10 months in 2019 explodes to cause fire, the action time of a circuit protection device is too slow, a power supply cannot be timely cut off, 2 death accidents are finally caused, and the training is very tragic, as shown in fig. 1. Under the requirements of electrical fire and personal protection, arc protection technology is rapidly developed, GB/T14598.302-2016 technical requirement of arc protection devices provides two modes of arc fault removal within 20ms of action time for the arc protection devices of a power distribution system, arc protection logic has an arc single criterion and arc and current double criteria, at present, the double criteria are mostly applied, the action logic of the protection devices is shown in figure 2, arc probes and current sensors are installed at multiple positions, but fault line selection/phase selection is not carried out due to the limit value of the arc protection logic, so that outlet trip signals are generally sent to an incoming line breaker, the power failure range is expanded, and the power supply reliability is influenced.
Disclosure of Invention
The invention aims to solve the technical problem of providing a line selection method, a device and a system for short-circuit protection of a power distribution system.
The technical scheme adopted by the invention is as follows: a line selection method for short-circuit protection of a power distribution system comprises the following steps:
step one, an arc light signal F is used as a starting signal of the accurate short-circuit protection method of the power distribution system, Fset represents an arc light sensor threshold set when a protection device is installed, when F is larger than or equal to Fset, the second step is carried out, otherwise, the first step of detection is continued;
step two, delaying time T;
thirdly, collecting current signals in the power distribution system from the protection winding, and removing power frequency quantity 50Hz current signals through Fourier transform to obtain all characteristic frequency band information except power frequency;
fourth step, using a defined peak-to-valley detector
fifthly, judging the sudden change energy of the line i, and defining the sudden change energy E (k) of the line i:
in the formula,. DELTA.Ii(n) is the line current break, Δ Ii(n)＝Ii(n)-Ii(n-1), wherein n is the current acquisition point, K is the number of acquisition points in a certain time window, and when the mutation energy is more than or equal to IiWhen the current energy of the ith line is multiplied by mu times of (n), the current energy of the ith line can be judged to be suddenly changed, namely the ith line is really a fault line, otherwise, the current energy is returned to the first step;
and sixthly, operating the arc light protection device.
The arc light signal F is the light intensity or illuminance detected by the visible light sensor or the ultraviolet light sensor, the current signal is a three-phase or one-phase or two-phase current signal acquired by a current transformer protective-stage coil, and the current signal is a waveform signal of the first quarter period after the short-circuit fault of the current transformer.
The delay time T is more than or equal to 0ms and less than or equal to 10 ms; the value of mu is 0.2 or more and 1 or less.
In the fourth step, after De (t) is obtained through calculation of a plurality of points, the absolute value of De (t) is calculated, if the maximum value is a peak, d is calculatediIs 1, if the maximum is a valley, diIs-1.
The number of points is 3-5 points, with 4 points being most suitable.
And the action of the arc light protection device in the sixth step means that the circuit i is powered off, and an alarm is given out at the same time.
A line selection device for short-circuit protection of a power distribution system comprises an input end, a processor and an output end, wherein the input end and the output end are connected with the processor;
the input end is used for receiving arc signals F and current signals of each line;
the processor is used for accurately judging whether each line simultaneously meets a first standard element and a second standard element according to the signals received by the input end, if so, the line can be judged to be a fault line, and the first standard is that after the optical parameter exceeds a threshold value, the current information also generates sudden change after the delay of T time; the second standard is that after the current information rejects the power frequency information, a defined peak-valley detector is utilized to judge that the current mutation direction of the line is abnormal according to the principle that the peak-valley shape of the head wave head of the fault line is opposite to the integral peak-valley shape of the head wave head of the current of each line, and then the current mutation intensity of the line with the current mutation direction is also abnormal;
and the output end is used for carrying out power-off processing on the fault line according to the output signal of the processor.
The output end performs sound-light alarm while performing power-off treatment on a fault line;
the specific method for judging whether the current mutation strength of the line with the abnormal current mutation direction is abnormal is as follows:
judging the sudden change energy of the line i, and defining the sudden change energy E (k) of the line i:in the formula,. DELTA.Ii(n) is the line current break, Δ Ii(n)＝Ii(n)-Ii(n-1), wherein n is the current acquisition point, K is the number of acquisition points in a certain time window, and when the mutation energy is more than or equal to IiWhen the current is multiplied by mu (n), the current energy of the ith line can be judgedThe magnitude changes abruptly, i.e. the ith line is indeed a faulty line.
The utility model provides a distribution system short-circuit protection's route selection system which characterized in that: the line selection device comprises a plurality of line selection devices for short-circuit protection of the power distribution system, wherein processors in the line selection devices for short-circuit protection of each power distribution system are connected with each other, and an agreement is achieved: and after the line selection device for short-circuit protection of any power distribution system detects a fault line, the line selection device for short-circuit protection of other power distribution systems is informed.
The consistent protocol is a hand-in-hand protocol.
The invention has the beneficial effects that:
1) reliability: through deep research, the morphological information rule of the current information in the short-circuit protection is found, and the method is high in repetition and good in stability.
2) The accuracy is as follows: a large number of simulation and practice researches are carried out, the accuracy and the effectiveness of protection selection are proved, and the worry of users is eliminated.
3) And (3) selectivity: the invention solves the defect that the traditional arc light protection can only provide alarm and trip signals but has no selectivity, purposefully selects out a fault line, avoids the integral power failure of a bus or a switch cabinet, and solves the problem of selective power supply or power failure of a power system.
Drawings
FIG. 1 is a combination transformer (oil immersed) explosion incident scene;
FIG. 2 is a logic diagram of a conventional arc protection device;
FIG. 3 is a flow chart of a method of selecting lines for short circuit protection of a power distribution system in accordance with the present invention;
FIG. 4 is a block diagram of a line selection device for short circuit protection of the power distribution system of the present invention;
fig. 5 is a schematic diagram of the installation of the switch cabinet of the line selection device for short-circuit protection of the power distribution system.
Detailed Description
Features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is in no way limited to any specific configuration and algorithm set forth below, but rather covers any modification, replacement or improvement of elements, components or algorithms without departing from the spirit of the invention. In the drawings and the following description, well-known structures and techniques are not shown in order to avoid unnecessarily obscuring the present invention.
This specification refers to "one embodiment" or "an embodiment" or "one example" or "an example". The appearances of phrases such as "in one embodiment" or "in an embodiment" are not necessarily referring to the same embodiment or example. The particular features, structures, or characteristics may be combined in any suitable manner consistent with the present disclosure.
Example 1: a line selection method for short-circuit protection of a power distribution system comprises the following steps:
step one, an arc light signal F is used as a starting signal of the accurate short-circuit protection method of the power distribution system, Fset represents an arc light sensor threshold set when a protection device is installed, when F is larger than or equal to Fset, the second step is carried out, otherwise, the first step of detection is continued;
step two, delaying time T;
thirdly, collecting current signals in the power distribution system from the protection winding, and removing power frequency quantity 50Hz current signals through Fourier transform to obtain all characteristic frequency band information except power frequency;
fourth step, using a defined peak-to-valley detector
fifthly, judging the sudden change energy of the line i, and defining the sudden change energy E (k) of the line i:
in the formula,. DELTA.Ii(n) is the line current break, Δ Ii(n)＝Ii(n)-Ii(n-1), wherein n is the current acquisition point, K is the number of acquisition points in a certain time window, and when the mutation energy is more than or equal to IiWhen the current energy of the ith line is multiplied by mu times of (n), the current energy of the ith line can be judged to be suddenly changed, namely the ith line is really a fault line, otherwise, the current energy is returned to the first step;
and sixthly, operating the arc light protection device.
The arc light signal F is the light intensity or illuminance detected by the visible light sensor or the ultraviolet light sensor, the current signal is a three-phase or one-phase or two-phase current signal acquired by a current transformer protective-stage coil, and the current signal is a waveform signal of the first quarter period after the short-circuit fault of the current transformer.
Furthermore, the delay time T is greater than or equal to 0ms and less than or equal to 10 ms. When the current mutation intensity is calculated, the value mu is similar to the current setting value, can be a certain multiple of the rated current and is a coefficient related to the sampling frequency, and when the rated current is 1A, the value mu is greater than or equal to 0.02, less than or equal to 1, preferably greater than or equal to 0.2.
Furthermore, in the fourth step, after De (t) is obtained through calculation of a plurality of points, the absolute value of De (t) is calculated, and if the maximum value is a peak, d is calculatediIs 1, if the maximum is a valley, diIs-1. The number of points is 3-5 points, with 4 points being most suitable.
Further, the action of the arc light protection device in the sixth step means that the circuit i is powered off, and an alarm is given out at the same time.
A line selection device for short-circuit protection of a power distribution system comprises an input end, a processor and an output end, wherein the input end and the output end are connected with the processor;
the input end is used for receiving arc signals F and current signals of each line;
the processor is used for judging which line is a fault line by adopting the line selection method for short-circuit protection of the power distribution system, and the specific expression is as follows: the processor accurately judges whether each line simultaneously meets a first standard element and a second standard element according to the signal received by the input end, if so, the line can be judged to be a fault line, and the first standard is that after the optical parameter exceeds a threshold value, the current information also generates sudden change after the delay of T time; the second standard is that after the current information rejects the power frequency information, a defined peak-valley detector is utilized to judge that the current mutation direction of the line is abnormal according to the principle that the peak-valley shape of the head wave head of the fault line is opposite to the integral peak-valley shape of the head wave head of the current of each line, and then the current mutation intensity of the line with the current mutation direction is also abnormal;
and the output end is used for carrying out power-off processing on the fault line according to the output signal of the processor.
Furthermore, the output end performs sound-light alarm while performing power-off treatment on the fault line;
the specific method for judging whether the current mutation strength of the line with the abnormal current mutation direction is abnormal is as follows:
judging the sudden change energy of the line i, and defining the sudden change energy E (k) of the line i:
in the formula,. DELTA.Ii(n) is the line current break, Δ Ii(n)＝Ii(n)-Ii(n-1), wherein n is the current acquisition point, K is the number of acquisition points in a certain time window, and when the mutation energy is more than or equal to IiAnd (n) is more than mu, the current energy of the ith line can be judged to be suddenly changed, namely, the ith line is really a fault line.
A line selection system for short-circuit protection of a power distribution system comprises a plurality of line selection devices for short-circuit protection of the power distribution system, wherein processors in the line selection devices for short-circuit protection of each power distribution system are connected with each other and reach an agreement: and after the line selection device for short-circuit protection of any power distribution system detects a fault line, the line selection device for short-circuit protection of other power distribution systems is informed.
Further, protocols among the processors can adopt various commonly used protocols in the prior art, and the consistent protocol in the embodiment is a hand-in-hand protocol, which is simple and effective.
The invention includes current signal and arc light signal, two criteria take and operation to export, regard arc light signal as the starting signal of the accurate protection method of short circuit of the power distribution system, through certain time delay, regard current signal as the movement signal of the accurate protection method of short circuit of the power distribution system, namely get and operation, change the tradition directly, have certain time delay sequence control, can raise the reliability of the protection method effectively, give consideration to the contradiction of accuracy and sensibility.
Further, the method specifically comprises the following steps:
the first step is as follows: the arc light signal F is used as a starting signal of the power distribution system short circuit accurate protection method, the F represents the light intensity or illuminance detected by the collected visible light or ultraviolet light sensor, the Fset represents the arc light sensor threshold value set when the protection device is installed, when the F is larger than or equal to the Fset, the second step is carried out, otherwise, the first step of detection is continuously started;
the second step is that: delaying; the delay time is generally greater than or equal to 0ms and less than or equal to 10 ms.
The third step: acquiring current information from the protection winding, and removing power frequency quantity 50Hz current information through Fourier transform to obtain all characteristic frequency band information except power frequency;
fourth step, using a defined peak-to-valley detector
In the formula: operator OthiDefining the peak point data of the current under the characteristic frequency band; operator ObhiThe valley point data of the current under the characteristic frequency band is defined, i (t) g (n) represents that two signals are subjected to graphic morphology closed operation,
representing two signals to carry out graphical morphological open operation to obtain the direction d of fault current mutationi，diRepresenting the direction of the ith line current sudden change, defining a line sudden change direction S:s is the integral mutation direction of the current bow wave head under each line characteristic frequency band, the i-th mutation direction is judged according to the principle that the peak-valley shape of the fault line bow wave head under the characteristic frequency band is opposite to the integral peak-valley shape of the current bow wave head of each line, the fault line is supposed to enter the fifth step, and otherwise, the fault line returns to the third step;
fifthly, judging the sudden change energy of the line after the sudden change direction is the fault line, and defining the sudden change energy E (k) of the line:
in the formula,. DELTA.Ii(n) is the line current break, Δ Ii(n)＝Ii(n)-Ii(n-1), wherein n is the current acquisition point, K is the number of acquisition points in a certain time window, and when the mutation energy is more than or equal to IiWhen the mu times of the (n), the current energy of the ith line is judged to be suddenly changed, namely the ith line is a fault line, otherwise, the first step is returned;
and sixthly, the arc light protection device acts, and the ith line is a fault line.
Further, in the fourth step, De (t) is a peak-valleyA detector, defined as follows:
in the formula: operator ObhiDefined as the valley point data of the current at the characteristic frequency band,indicates that the two signals are subjected to graphic morphological closed operation,showing that both signals are graphically and morphologically on-operated. The open operation is defined as erosion followed by expansion, i.e.
Wherein
And
respectively, corrosion and swelling. Closed-loop operation is defined as expansion followed by erosion, i.e.
Further, after De (t) is obtained through calculation of a plurality of points, the absolute value of De (t) is calculated, and if the maximum value is a peak, d is calculatediIs 1, if the maximum is a valley, diIs-1. And then, the abrupt change directions under different line characteristic frequency bands are obtained through the definition of the line abrupt change directions. A plurality of points generally carry out corresponding values within 10ms, and the values are 3-5 points, and are most suitable when the points are 4 points.
Further, when calculating the current sudden change intensity, the μ value is similar to the current setting value, and may be a certain multiple of the rated current, which is a coefficient related to the sampling frequency, and assuming that the rated current is 1A, the μ value is greater than or equal to 0.02, less than or equal to 1, and preferably greater than or equal to 0.2.
Generating unit of neutral point through arc suppression coil grounding systemWhen the phase grounding fails, an obvious transient process exists, and the transient information belongs to the mutation quantity. Mutation detection by morphological operators is actually a peak-valley detection. The starting operation in morphology is a non-expansion operation on signals, the contour of a target signal can be smooth, and burrs are removed to inhibit peak noise in the signal; the closed operation is an expansion operation, and can fill and level off the valley and the crack so as to filter the low valley noise in the signal. Subtracting the result of the over-open operation from the original current signal to obtain the mark point of the peak point, i.e. the Top-Hat operator OthSubtracting the result of the over-closing operation from the original current signal to obtain a mark point at the valley point, namely a Bottom-Hat operator Obh。
In mathematical morphology operation, the shape and size of the structural elements have a large influence on the signal processing result. The current signal characteristics of the power system and the requirement of simplifying program resources are combined, a linear structural element is selected, the linear structural element and the horizontal direction form 0 degree, and when noise elimination is carried out, the shape of a signal can be kept, and the noise in the shape of burrs can be eliminated to a large extent. And performing morphological peak-valley detection on the current signals under the characteristic frequency band, and detecting the peak and the valley of the zero-sequence current characteristic frequency band of each line by applying a mathematical morphology Top-Hat operator and a Bottom-Hat operator so as to better show the peak-valley characteristics.
And determining the mutation direction and intensity of the transient information mutation obvious points after the fault by using the peak-valley detector De (t). After the fault, usually the sudden change intensity of the current of the fault line is the largest, and due to the complex field environment, the sudden change intensity of some sudden change points of the fault line can be smaller than that of the healthy line, but the sudden change trend of the fault line is necessarily opposite to that of the healthy line. Therefore, by using morphological peak-valley detection, the formed criterion fully reflects the transient process of the single-phase earth fault according to the fact that the peak-valley shape of the head wave of the fault line under the characteristic frequency band is opposite to the integral peak-valley shape of the current head wave of each line, and the criterion is consistent with the actual situation.
Line break direction S definition:wherein S is the overall mutation direction of the current bow wave head under the characteristic frequency band of each line, d is d when the ith line bow wave head is detected as the peaki1, when a valley is detected, diIs-1, i is the number of lines.
And (3) processing detection results:
1) when d isiThe xSS is less than 0, the peak-valley form of the head wave head corresponding to the ith line is opposite to the peak-valley form of the whole line, and the ith line is judged to be a fault line;
2) when d isiThe xSS is more than 0, the peak-valley form of the head wave head corresponding to the ith line is the same as the peak-valley form of the whole line, and the ith line is judged to be a normal line;
3) when d isiX S is greater than 0(i is 1,2, …, N), which indicates that the head wave head peak valley forms of all the outgoing lines are the same, and the bus is determined to be a fault line;
line break energy e (k) definition:
in the formula,. DELTA.Ii(n) is the line current break, Δ Ii(n)＝Ii(n)-Ii(n-1), wherein n is the current acquisition point, and K is the number of acquisition points in a certain time window.
And (3) processing detection results:
1) when the mutation energy is more than or equal to IiWhen the current energy of the ith line is multiplied by mu, the current energy of the ith line can be judged to be suddenly changed, namely the ith line is a fault line;
2) when the mutation energy is less than IiAnd (n) is multiplied by mu, the current energy of the ith line can be judged to have no sudden change, namely the ith line is a normal line.
As shown in fig. 1, when a line device is overhauled at present, due to the lack of a corresponding fast-acting protection device, when a fault exists, the protection device does not act correspondingly, so that great losses of device burnout and casualties are caused, and fig. 1 is a scene photo of the device burnout.
As shown in fig. 2, the conventional arc protection device without line selection or phase selection function is a functional block diagram, and mainly includes two criteria of current and arc, wherein the same type of sensor is operated by taking an or, and two different criteria are operated by taking an and, and a tripping outlet signal is output; two different criterions are subjected to OR operation to output alarm outlet signals.
As shown in fig. 3, the arc characteristics of the arc in the overvoltage state of the switchgear are that a foreign scholars propose a Cassie mathematical model and a Mayr mathematical model, the Cassie model is mainly suitable for a large-current arc period before the current zero-crossing, the Mayr model is mainly suitable for a small-current period when the current zero-crossing occurs, and different arc equations are adopted at different moments to simulate the whole process of arc motions, so that the arc characteristics are more suitable for actual conditions (the Cassie model is used before the current zero-crossing, and the Mayr model is used after the current zero-crossing).
Based on the analysis, the arc protection line selection technology is provided by taking the arc criterion as a starting criterion, performing morphological analysis on current transient state quantity and taking the current criterion as an exit criterion, namely, the line selection/phase selection function is realized on the basis of keeping the accuracy and the sensitivity of the traditional arc protection, more accurate positioning is realized, the selectivity of the arc protection technology is improved, and a theoretical basis is provided for more accurate arc fault line selection.
According to the Cassie arc model principle, the principle of energy balance can be derived:
in the formula:
is the change in energy stored in the arc column per unit length; e.j is the input power per unit length of arc length, j is the arc current, e is the electric field strength in the arc column; p is the power loss per arc length.
Since the resistance value is very small during arc combustion, the model can be expressed in the form of conductance, and equation (1) is further converted into:
where g is the arc conductance and T is g · dq/dg, we can derive:
considering that the length of the arc is L and u is the arc voltage, u is L × e; p0Is the power loss of the arc column, then P0Referring to the small current conductance change of Mayr, we can obtain:
when the electric conductance of the arc column is converted from G to stable electric conductance G, the arc is stably burnt, and the input energy of the arc is equal to the dissipated energy. I.e. P0＝I2and/G. Thereby obtaining:
wherein G is the arc steady state conductance; g is arc conductance; t is an arc time constant, and an arc generated by a transient fault can be divided into a primary arc (after the fault occurs and before the circuit breaker trips) and a secondary arc (after the circuit breaker trips) according to arc characteristics. The invention mainly discusses a primary electric arc, and the model of the primary electric arc is as follows:
from equation (6), the short-circuit arc of the distribution system is closely related to the stable conductance, i.e. the high-frequency information characteristic of the current. The above equations (1) to (6) are prior art and will not be described in further detail here.
As shown in FIG. 3, the short-circuit protection optical parameter still requires Fset setting, i.e. opticsSetting a threshold, judging the sudden change direction of the line by morphological information when judging current information later, and judging the sudden change intensity of the line by sampling the square of the current information difference between the previous moment and the later moment of the information, wherein the intensity can be equal to IiThe mu-time hook of (n) can also be hooked with k times of rated current of the line, generally more accurate with a real-time current hook, more convincing with the rated current hook (the value range of k can be selected to be more than or equal to 0.1, and less than or equal to FS coefficient of a current transformer protection winding, such as 6).
As shown in fig. 4, the block diagram of the short-circuit protection device is mainly related to the device developed with reference to the short-circuit protection method, and the functions of the specific device and the steps of the protection method are substantially identical.
As shown in fig. 5, the block diagram of the short-circuit protection system is mainly related to a system developed with reference to the short-circuit protection method, and the functions of the specific system and the steps of the protection method are substantially the same.
As shown in fig. 5, the newly developed installation and maintenance block diagram of the line selection device for short-circuit protection of the power distribution system is provided with a plurality of corresponding arc sensors and current collectors, and here, taking the primary structure of the double bus sections as an example, according to the line selection method, the tripping of the incoming line switch or the bus switch or the feeder switch can be accurately implemented, so that the short-circuit protection has better selectivity. This can be a particularly installed and functional embodiment of the present invention.
While the present invention has been described with reference to the embodiments, the present invention is not limited to the embodiments and various changes can be made without departing from the spirit and scope of the present invention.
Claims (10)
1. A line selection method for short-circuit protection of a power distribution system is characterized by comprising the following steps: the method comprises the following steps:
step one, an arc light signal F is used as a starting signal of the accurate short-circuit protection method of the power distribution system, Fset represents an arc light sensor threshold set when a protection device is installed, when F is larger than or equal to Fset, the second step is carried out, otherwise, the first step of detection is continued;
step two, delaying time T;
thirdly, collecting current signals in the power distribution system from the protection winding, and removing power frequency quantity 50Hz current signals through Fourier transform to obtain all characteristic frequency band information except power frequency;
fourth step, using a defined peak-to-valley detector
In the formula: operator OthiDefining the peak point data of the current under the characteristic frequency band; operator ObhiThe valley point data defined as the current under the characteristic frequency band, i (t) g (n) represents the closed operation of the two signals by the graphic morphology,
showing that the two signals are subjected to graphical morphological opening operation, and obtaining the direction d of the fault current mutation according to De (t)i，diRepresenting the direction of the ith line current sudden change, defining a line sudden change direction S:
in the formula, S is the integral mutation direction of the current bow wave head of each line characteristic frequency band, the mutation line possibly with faults is judged to be a line i according to the principle that the peak-valley shape of the fault line bow wave head under the characteristic frequency band is opposite to the integral peak-valley shape of the current bow wave head of each line, and if the mutation line possibly with faults is not found, the third step is returned;
fifthly, judging the sudden change energy of the line i, and defining the sudden change energy E (k) of the line i:
in the formula,. DELTA.Ii(n) is the line current break, Δ Ii(n)＝Ii(n)-Ii(n-1), wherein n is the current acquisition point, K is the number of acquisition points in a certain time window, and when the mutation energy is more than or equal to IiWhen the current energy of the ith line is multiplied by mu times of (n), the current energy of the ith line can be judged to be suddenly changed, namely the ith line is really a fault line, otherwise, the current energy is returned to the first step;
and sixthly, operating the arc light protection device.
2. The line selection method for short-circuit protection of the power distribution system according to claim 1, characterized in that: the arc light signal F is the light intensity or illuminance detected by the visible light sensor or the ultraviolet light sensor, the current signal is a three-phase or one-phase or two-phase current signal acquired by a current transformer protective-stage coil, and the current signal is a waveform signal of the first quarter period after the short-circuit fault of the current transformer.
3. The line selection method for short-circuit protection of the power distribution system according to claim 1, characterized in that: the delay time T is more than or equal to 0ms and less than or equal to 10 ms; the value of mu is 0.2 or more and 1 or less.
4. The line selection method for short-circuit protection of the power distribution system according to claim 1, characterized in that: in the fourth step, after De (t) is obtained through calculation of a plurality of points, the absolute value of De (t) is calculated, if the maximum value is a peak, d is calculatediIs 1, if the maximum is a valley, diIs-1.
5. The line selection method for short-circuit protection of the power distribution system according to claim 4, wherein: the number of points is 3-5 points, with 4 points being most suitable.
6. The line selection method for short-circuit protection of the power distribution system according to claim 1, characterized in that: and the action of the arc light protection device in the sixth step means that the circuit i is powered off, and an alarm is given out at the same time.
7. The utility model provides a distribution system short-circuit protection's route selection device which characterized in that: the system comprises an input end, a processor and an output end, wherein the input end and the output end are connected with the processor;
the input end is used for receiving arc signals F and current signals of each line;
the processor is used for accurately judging whether each line simultaneously meets a first standard element and a second standard element according to the signals received by the input end, if so, the line can be judged to be a fault line, and the first standard is that after the optical parameter exceeds a threshold value, the current information also generates sudden change after the delay of T time; the second standard is that after the current information rejects the power frequency information, a defined peak-valley detector is utilized to judge that the current mutation direction of the line is abnormal according to the principle that the peak-valley shape of the head wave head of the fault line is opposite to the integral peak-valley shape of the head wave head of the current of each line, and then the current mutation intensity of the line with the current mutation direction is also abnormal;
and the output end is used for carrying out power-off processing on the fault line according to the output signal of the processor.
8. The line selection device for short-circuit protection of the power distribution system according to claim 7, wherein: the output end performs sound-light alarm while performing power-off treatment on a fault line;
the specific method for judging whether the current mutation strength of the line with the abnormal current mutation direction is abnormal is as follows:
judging the sudden change energy of the line i, and defining the sudden change energy E (k) of the line i:
in the formula,. DELTA.Ii(n) is the line current break, Δ Ii(n)＝Ii(n)-Ii(n-1), wherein n is the current acquisition point, K is the number of acquisition points in a certain time window, and when the mutation energy is more than or equal to IiWhen the current energy of the ith line is multiplied by mu times of (n), the current energy of the ith line can be judged to be suddenly changed, namely the ith line is really a fault line;
and the output end performs sound-light alarm while performing power-off treatment on the fault line.
9. The utility model provides a distribution system short-circuit protection's route selection system which characterized in that: a line selection device comprising a plurality of power distribution system short circuit protection devices as claimed in claim 7, wherein the processors of each of the line selection devices are interconnected and agree to: and after the line selection device for short-circuit protection of any power distribution system detects a fault line, the line selection device for short-circuit protection of other power distribution systems is informed.
10. The line selection system for short circuit protection of a power distribution system of claim 9, wherein: the consistent protocol is a hand-in-hand protocol.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910918105.8A CN110794326A (en) | 2019-09-26 | 2019-09-26 | Line selection method, device and system for short-circuit protection of power distribution system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910918105.8A CN110794326A (en) | 2019-09-26 | 2019-09-26 | Line selection method, device and system for short-circuit protection of power distribution system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN110794326A true CN110794326A (en) | 2020-02-14 |
Family
ID=69439868
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910918105.8A Pending CN110794326A (en) | 2019-09-26 | 2019-09-26 | Line selection method, device and system for short-circuit protection of power distribution system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110794326A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024027455A1 (en) * | 2022-08-01 | 2024-02-08 | 云南电力试验研究院(集团)有限公司 | Arc spectrum identification method and apparatus |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5834940A (en) * | 1996-09-24 | 1998-11-10 | Brooks; Stanley J. | Arcing fault detector testing and demonstration system |
| CN1423132A (en) * | 2001-11-28 | 2003-06-11 | 淄博科汇电气有限公司 | Small-current earth fault switch-selecting and sectioning method for power system |
| CN102129012A (en) * | 2011-01-21 | 2011-07-20 | 昆明理工大学 | Distribution network fault line selection method using form peak valley detection |
| CN103954884A (en) * | 2014-04-21 | 2014-07-30 | 昆明理工大学 | Distribution network fault line selection method based on extensional fusion of pattern spectrum analysis and morphological peak and valley detection |
| CN104133158A (en) * | 2014-08-04 | 2014-11-05 | 昆明理工大学 | Distribution network fault line selection method based on zero-mode current multi-order difference transformation |
| CN205724867U (en) * | 2016-06-24 | 2016-11-23 | 西安科技大学 | A kind of small current grounding system single-phase grounding selecting protection device |
| CN106410970A (en) * | 2016-11-11 | 2017-02-15 | 南京南瑞继保电气有限公司 | Arc light protective device and method with light intensity signal recording function |
| US20170117699A1 (en) * | 2011-07-29 | 2017-04-27 | Leviton Manufacturing Company | Arc fault circuit interrupter |
| CN109406948A (en) * | 2018-12-10 | 2019-03-01 | 贵州电网有限责任公司 | The distribution single-phase earth fault detecting method merged using transient state and steady state characteristic |
| CN110146782A (en) * | 2019-05-15 | 2019-08-20 | 上海宏力达信息技术股份有限公司 | A kind of ground fault line selecting method |
| CN110176752A (en) * | 2019-07-03 | 2019-08-27 | 云南电网有限责任公司电力科学研究院 | Switchgear arc light protection method and device |
-
2019
- 2019-09-26 CN CN201910918105.8A patent/CN110794326A/en active Pending
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5834940A (en) * | 1996-09-24 | 1998-11-10 | Brooks; Stanley J. | Arcing fault detector testing and demonstration system |
| CN1423132A (en) * | 2001-11-28 | 2003-06-11 | 淄博科汇电气有限公司 | Small-current earth fault switch-selecting and sectioning method for power system |
| CN102129012A (en) * | 2011-01-21 | 2011-07-20 | 昆明理工大学 | Distribution network fault line selection method using form peak valley detection |
| US20170117699A1 (en) * | 2011-07-29 | 2017-04-27 | Leviton Manufacturing Company | Arc fault circuit interrupter |
| CN103954884A (en) * | 2014-04-21 | 2014-07-30 | 昆明理工大学 | Distribution network fault line selection method based on extensional fusion of pattern spectrum analysis and morphological peak and valley detection |
| CN104133158A (en) * | 2014-08-04 | 2014-11-05 | 昆明理工大学 | Distribution network fault line selection method based on zero-mode current multi-order difference transformation |
| CN205724867U (en) * | 2016-06-24 | 2016-11-23 | 西安科技大学 | A kind of small current grounding system single-phase grounding selecting protection device |
| CN106410970A (en) * | 2016-11-11 | 2017-02-15 | 南京南瑞继保电气有限公司 | Arc light protective device and method with light intensity signal recording function |
| CN109406948A (en) * | 2018-12-10 | 2019-03-01 | 贵州电网有限责任公司 | The distribution single-phase earth fault detecting method merged using transient state and steady state characteristic |
| CN110146782A (en) * | 2019-05-15 | 2019-08-20 | 上海宏力达信息技术股份有限公司 | A kind of ground fault line selecting method |
| CN110176752A (en) * | 2019-07-03 | 2019-08-27 | 云南电网有限责任公司电力科学研究院 | Switchgear arc light protection method and device |
Non-Patent Citations (2)
| Title |
|---|
| SU YONGZHI 等: "The transient analysis of electronic arc-suppression coil and its effect on transient based fault line selection for single phase to earth fault", 《2011 THE INTERNATIONAL CONFERENCE ON ADVANCED POWER SYSTEM AUTOMATION AND PROTECTION 》 * |
| 束洪春 等: "采用形态学峰谷检测的谐振接地系统故障选线方法", 《电力系统自动化》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024027455A1 (en) * | 2022-08-01 | 2024-02-08 | 云南电力试验研究院(集团)有限公司 | Arc spectrum identification method and apparatus |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107064741B (en) | A kind of successive ground fault line selecting method of distribution network line different name phase two o'clock | |
| Zhang et al. | Fault analysis and traveling-wave protection scheme for bipolar HVDC lines | |
| CN111398733B (en) | Ocean nuclear power platform power grid ground fault line selection protection method and system | |
| CN109742727B (en) | Method for judging low-voltage 400V leakage current | |
| CN106199341B (en) | Fault line identification method and device under single-phase fault grounding working condition | |
| CN111934280B (en) | Electric leakage fault detection method and device, storage medium and power distribution gateway | |
| CN107390010B (en) | Method for rapidly detecting trailing current of current transformer | |
| CN110261714B (en) | Short-circuit fault rapid detection method applied to current limiter | |
| CN107561408B (en) | Method for improving accuracy rate of small current ground fault line selection | |
| CN104852354A (en) | Adaptive-slope transformer zero-sequence differential protection method and device | |
| CN100387999C (en) | Circuit fault directional detecting and protecting method for power supply system | |
| CN112230100A (en) | Slow-development permanent fault early warning method and system | |
| CN108258662A (en) | A kind of multiterminal flexible direct current distribution line transient protection method and device | |
| CN101593972B (en) | Fault line selection method for resonant grounded power distribution system by pattern spectrum | |
| CN105301426B (en) | A kind of multi-layer selectivity low-voltage short-circuiting Protection system | |
| CN104577999A (en) | Bus protection method and system based on transient-state zero-sequence current characteristic | |
| CN111751719A (en) | Method and system for judging transformer protection trip edge based on power grid fault recording diagram | |
| CN103532113A (en) | Rapid distance protection method for power transmission line containing micro-grid system | |
| CN110794340B (en) | Disconnection protection method and circuit for high-voltage overhead line | |
| CN110518557A (en) | A kind of fault current limiter input control method based on short circuit current integrated information | |
| CN110794326A (en) | Line selection method, device and system for short-circuit protection of power distribution system | |
| WO2021052300A1 (en) | High-voltage hybrid line fault section discrimination method using ratio restraint differential principle | |
| CN112731211A (en) | Grounding transformer low-voltage winding turn-to-turn short circuit fault and phase identification method | |
| CN108241105A (en) | A kind of test method of the arc grounding line selection apparatus based on RTDS | |
| CN101958579A (en) | Method of treating information loss in centralized protection device of digitalized substation |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| AD01 | Patent right deemed abandoned |
Effective date of abandoning: 20211126 |
|
| AD01 | Patent right deemed abandoned |