CN117706281A - Fault line selection method, system and storage medium for power distribution network based on phase asymmetry - Google Patents
Fault line selection method, system and storage medium for power distribution network based on phase asymmetry Download PDFInfo
- Publication number
- CN117706281A CN117706281A CN202410161410.8A CN202410161410A CN117706281A CN 117706281 A CN117706281 A CN 117706281A CN 202410161410 A CN202410161410 A CN 202410161410A CN 117706281 A CN117706281 A CN 117706281A
- Authority
- CN
- China
- Prior art keywords
- phase
- fault
- symmetry
- phase current
- feeder
- 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
- 238000009826 distribution Methods 0.000 title claims abstract description 79
- 238000010187 selection method Methods 0.000 title claims abstract description 25
- 238000003860 storage Methods 0.000 title claims abstract description 20
- 238000000034 method Methods 0.000 claims abstract description 31
- 238000012545 processing Methods 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 4
- 238000012216 screening Methods 0.000 claims description 3
- 230000001105 regulatory effect Effects 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 7
- 238000010586 diagram Methods 0.000 description 13
- 238000004364 calculation method Methods 0.000 description 12
- 238000004590 computer program Methods 0.000 description 10
- 230000001052 transient effect Effects 0.000 description 8
- 230000004048 modification Effects 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 238000001514 detection method Methods 0.000 description 4
- 230000006870 function Effects 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000004088 simulation Methods 0.000 description 3
- 230000001629 suppression Effects 0.000 description 3
- 230000004075 alteration Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 230000016507 interphase Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 101100499229 Mus musculus Dhrsx gene Proteins 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000013179 statistical model Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
Abstract
The invention relates to the technical field of power systems, in particular to a fault line selection method, a fault line selection system and a fault line selection storage medium for a power distribution network based on phase asymmetry. The method comprises the following steps: acquiring three-phase current fault components of each feeder line、、And performing three-phase symmetry treatment to obtain three groups of symmetric currents of the feeder line, which are respectively、、Calculating symmetry degree rho among three groups of symmetrical currents; and determining a fault phase and a fault feeder line according to the symmetry degree. The method can also timely judge the distribution network with small current and accurately select lines, thereby achieving the effect of improving the safety and stability of the system.
Description
Technical Field
The invention relates to the technical field of relay protection of power systems, in particular to a fault line selection method, a system and a storage medium of a power distribution network based on phase asymmetry.
Background
With the rapid development of the quantity and the scale of the power distribution network in China, the operation and maintenance tasks of the power distribution network become increasingly heavy. The single-phase earth fault line selection problem of the power distribution network is difficult to solve, and the following main reasons are: the fault boundaries are too complex and random to describe with a single statistical model; the fault steady-state component is small, which causes difficulty for signal detection and line selection judgment. In particular, the steady-state current flowing through the fault line is very weak and even smaller than the current change perceived by the sound line through the arc suppression coil grounding system. The fault signal is superimposed on the power frequency component current, the steady-state amplitude is small, the existing current transformer is difficult to accurately detect, the environment electromagnetic interference is relatively large, and the amplification effect of the zero sequence loop on higher harmonic waves and various transient quantities is added, so that the signal-to-noise ratio of the detected fault steady-state component is very low; the factors influencing the fault line selection accuracy and reliability of the low-current grounding system are numerous. How to effectively guarantee and improve the safe and reliable operation of the power distribution network relates to the safe and reliable problem of power consumption of users, so that power supply enterprises have to face a very important challenge, namely how to continuously guarantee and improve the safe and reliable power supply of the power distribution network.
However, the inventors have found at least the following drawbacks when they conceived and realized the present solution: for a neutral point through arc suppression coil grounding system, a fault transient current is small due to a small fault angle condition, and a fault line selection accuracy rate is low in a traditional mode of fault line selection based on a phase-contrast principle. Therefore, a fault line selection method is needed to be suitable for the neutral point through arc suppression coil grounding system.
Disclosure of Invention
The invention mainly aims to provide a fault line selection method of a power distribution network based on phase asymmetry, which aims to solve the problem of how to accurately detect the high-resistance grounded power distribution network.
In order to achieve the above object, the present invention provides a fault line selection method for a power distribution network based on phase asymmetry, the method comprising:
acquiring three-phase current fault components of each feeder line、、And performing three-phase symmetry treatment to obtain three groups of symmetric currents of the feeder line, which are respectively、、。
Calculating symmetry between three groups of symmetrical currents。
And determining a fault phase and a fault feeder line according to the symmetry degree.
Optionally, the acquiring three-phase current fault components of each feeder line、、And performing three-phase symmetry treatment to obtain three groups of symmetric currents of the feeder line, which are respectively、、The method comprises the following steps:
three groups of symmetrical currents for each feeder line、、The method comprises the following steps of:
wherein,、、current data symmetrical about the phase current is retrieved after processing for each feeder line respectively,、、each feeder A, B, C is a three-phase fault component.
Optionally, the symmetry degree between the three groups of symmetrical currents is calculatedThe method comprises the following steps:
comparing the three-phase current data of each feeder line obtained after each two phases are subtracted, and calculating the symmetry degree of the three-phase currentWhether A, B, C three phases of each feeder line are symmetrical or not is obtained.
Wherein,andthe symmetry of (2) is:
in the method, in the process of the invention,is of symmetry andthe absolute value of (2) is 1 or less,a larger value indicates a higher degree of symmetry;
based on the above equation, symmetry between each phase of each feeder line is calculated in turn.
Wherein,andthe symmetry of (2) is:
wherein,andthe symmetry of (2) is:
optionally, the step of determining the faulty phase and the faulty feeder according to the symmetry degree includes:
and (3) according to the relative symmetry degree of A, B, C three phases, forming a system criterion, and judging whether the feeder line fails or not and which one of A, B, C three phases fails according to the current symmetry of the three phases. The asymmetric phase is a fault phase, the symmetric phase is a normal phase, and the criterion is:
n=1, 2..a., j phase and i phase of the n-th feeder are symmetrical phases;
n=1, 2..a., the j-phase or i-phase of the nth feeder is an asymmetric phase and the nth feeder is a faulty feeder. And further continuously judging symmetry degrees of other interphase of the feeder line, and screening out fault phases.
In addition, in order to achieve the above object, the present invention further provides a fault line selection system based on a phase-asymmetric power distribution network, where the fault line selection system based on the phase-asymmetric power distribution network includes:
the data acquisition module is used for acquiring a pre-fault three-phase current value and a post-fault three-phase current value of the target feeder line when the power distribution network fails.
The numerical calculation module is used for determining a current difference value between the pre-fault three-phase current value and the post-fault three-phase current value, determining a de-power frequency component three-phase current corresponding to the post-fault three-phase current of the feeder line based on the current difference value, and determining the phase current symmetry degree of the de-power frequency component three-phase current.
And the logic judgment module is used for judging whether the symmetry degree of the phase current is smaller than a setting value. If yes, determining the target feeder line as a fault feeder line.
Optionally, the data acquisition module includes:
the data acquisition unit is used for acquiring bus zero sequence voltage signals and all feeder zero sequence current signals in real time.
And the analog-to-digital conversion unit is used for converting the acquired instantaneous values of the bus zero sequence voltage signal and the zero sequence current signals of all feeder lines into digital values of digital quantity signals.
Optionally, the numerical calculation module includes:
and the signal calculation unit is used for constructing a starting signal for the acquired bus zero sequence voltage.
A current difference value calculation unit before and after failure: and the current difference value between the three-phase current value before the fault and the three-phase current value after the fault is calculated.
Phase current symmetry calculation unit: and the phase current symmetry degree is used for calculating the power frequency component removing three-phase current.
Optionally, the logic determination module includes:
and the bus zero sequence voltage judging unit is used for determining whether the instantaneous value of the bus zero sequence voltage is larger than a preset voltage threshold value, wherein if so, the power distribution network fault is judged.
And the fault line selection judging unit is used for judging whether the symmetry degree of the phase current is smaller than a setting value, wherein if yes, the target feeder is determined to be a fault feeder.
In addition, in order to achieve the above object, the present invention further provides a computer readable storage medium, where a fault line selection program based on a phase-asymmetric power distribution network is stored, where the fault line selection program based on the phase-asymmetric power distribution network implements the steps of the fault line selection method based on the phase-asymmetric power distribution network as described above when being executed by a processor.
The invention provides a fault line selection method, a system and a readable storage medium for a power distribution network based on phase asymmetry, which are used for determining the phase current symmetry degree of a three-phase current with a power frequency component removed by calculating the current difference between a three-phase current value before a fault and a three-phase current value after the fault, wherein the phase current symmetry degree is used as a line selection criterion, and the power distribution network with small current can be judged in time and is subjected to accurate line selection, so that the effect of improving the safety and the stability of the system is achieved.
Drawings
Fig. 1 is a schematic diagram of a fault line selection system of a power distribution network based on phase asymmetry according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a simulation model of a power distribution network;
fig. 3 is a schematic flow chart of a first embodiment of a fault line selection method for a power distribution network based on phase asymmetry of the present invention;
fig. 4 is a schematic flow chart of a second embodiment of a fault line selection method of a power distribution network based on phase asymmetry of the present invention;
FIG. 5 is a schematic diagram of current waveforms of the fault feeder after three-phase current subtraction;
FIG. 6 is a schematic diagram of current waveforms of normal feeder line three-phase currents after subtraction;
fig. 7 is a schematic flow chart of a third embodiment of a fault line selection method for a power distribution network based on phase asymmetry.
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
A three-phase reactance transformer is arranged on a feed-out line of the distribution network, most of newly-built substations meet the condition, and support is provided for extracting and utilizing three-phase transient currents of the feed-out line. In addition, in consideration of the fact that the transmission characteristics of the three-phase current transformer are often inconsistent, zero-mode current synthesized by the three-phase current has a certain deviation from the real situation, and the reliability of a fault line selection method based on the zero-mode current is directly affected. The feeder line of the distribution network has single-phase earth fault, and the three-phase current abrupt change of the sound feeder line is capacitance current to the ground, and the amplitude values are equal and the waveform is symmetrical; and the fault feeder line only has two sound phase currents which meet symmetry, are influenced by the fault current, and have different current symmetry of the fault phase and current symmetry of the sound phase, and the three-phase current of the fault feeder line does not have the characteristic of consistent current symmetry of the three-phase current of the sound feeder line. A faulty feeder can be identified by measuring A, B, C three-phase current symmetry consistency.
The symmetry of correspondence between healthy phase (B, C) is substantially consistent, and the symmetry of current between failed phase (a) and healthy phase (B, C) is poor, so this feature can be used for failure phase selection. For a fault feeder line, the symmetry difference between a fault phase and a sound phase is larger, and the circuit symmetry is smaller; and for sound feeders, the three-phase currents are symmetrical.
The power distribution network fault line selection method and system based on phase asymmetry can be used for protecting power distribution networks with different voltage levels and different view field views, and the method is flexibly configured on a 10-35kV overhead line, a cable line and an overhead-cable mixed line, can accurately identify single-phase grounding faults of the power distribution network, protects timely actions, timely isolates and eliminates the faults, and improves the stability of a power system.
In order to better understand the above technical solution, exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
As an implementation scheme, fig. 1 is a schematic architecture diagram of a fault line selection system of a power distribution network based on phase asymmetry according to an embodiment of the present invention.
As shown in fig. 1, the system includes a data acquisition module 101, a numerical calculation module 102, and a logic determination module 103. The data acquisition module 101 is used for acquiring a pre-fault three-phase current value and a post-fault three-phase current value of a target feeder line when a power distribution network fails; the numerical calculation module 102 is configured to determine a current difference between the pre-fault three-phase current value and the post-fault three-phase current value, determine a de-power frequency component three-phase current corresponding to the post-fault three-phase current of the feeder line based on the current difference, and determine a phase current symmetry degree of the de-power frequency three-phase current; the logic determination module 103 is configured to determine whether the symmetry degree of the phase current is less than a setting value. If yes, determining the target feeder line as a fault feeder line. Wherein:
the data acquisition module 101 may include a data acquisition unit 1011 and an analog-to-digital conversion unit 1012. The data acquisition unit 1011 is used for acquiring bus zero sequence voltage signals and all feeder zero sequence current signals in real time; the analog-to-digital conversion unit 1012 is used for converting the collected instantaneous values of the bus zero sequence voltage signal and the zero sequence current signal of each feeder line into digital values of digital quantity signals.
The numerical calculation module 102 may include a signal calculation unit 1021, a pre-fault-post-current difference calculation unit 1022, and a phase current symmetry calculation unit 1023. The signal calculating unit 1021 is configured to construct a start signal for the collected bus zero sequence voltage, the pre-fault and post-fault current difference calculating unit 1022 is configured to calculate a current difference between a pre-fault three-phase current value and the post-fault three-phase current value, and the phase current symmetry calculating unit 1023 is configured to calculate a phase current symmetry of the de-power frequency component three-phase current.
The logic determination module 103 may include a bus zero sequence voltage determination unit 1031 and a fault line selection determination unit 1032. The bus zero sequence voltage judging unit 1031 is used for judging whether the correlation coefficient is smaller than a setting value, wherein if yes, the target feeder is determined to be a fault feeder; the fault line selection judging unit 1032 is configured to judge whether the symmetry degree of the phase current is less than a setting value, where if not, it is determined that the target feeder is a normal feeder.
In addition, the fault line selection system based on the phase-asymmetric distribution network shown in fig. 1 further includes a memory 104 and a processor 105, where the memory 104 may be a high-speed RAM memory or a stable memory (non-volatile memory), such as a disk memory. The memory 104 is used for storing a phase-asymmetry-based power distribution network fault line selection program as a computer-readable storage medium, and the processor 105 may be used for calling the phase-asymmetry-based power distribution network fault line selection program stored in the memory 104 and performing the following operations:
acquiring three-phase current fault components of each feeder line、、And performing three-phase symmetry treatment to obtain three groups of symmetric currents of the feeder line, which are respectively、、。
Calculating symmetry between three groups of symmetrical currents。
And determining a fault phase and a fault feeder line according to the symmetry degree.
In one embodiment, the processor 105 may be configured to invoke a fault line selection procedure for the phase-asymmetry-based power distribution network stored in the memory 104, and perform the following operations:
determining a two-phase current difference between the first phase current and the second phase current;
and determining a two-three phase current difference between the second phase current and the third phase current;
and determining a three-phase current difference between the third phase current and the first phase current;
and determining the symmetry degree of the phase currents according to the two-phase current difference value, the two-three-phase current difference value and the three-one-phase current difference value.
In one embodiment, the processor 105 may be configured to invoke a fault line selection procedure for the phase-asymmetry-based power distribution network stored in the memory 104, and perform the following operations:
if at least one of the two-phase current difference value, the two-phase current difference value and the three-phase current difference value is not null, setting the phase current symmetry degree as a first phase current symmetry degree;
if the two-phase current difference value, the two-phase current difference value and the three-phase current difference value are all null values, setting the phase current symmetry degree as a second phase current symmetry degree;
in one embodiment, the processor 105 may be configured to invoke a fault line selection procedure for the phase-asymmetry-based power distribution network stored in the memory 104, and perform the following operations:
and (3) according to the relative symmetry degree of A, B, C three phases, forming a system criterion, and judging whether the feeder line fails or not and which one of A, B, C three phases fails according to the current symmetry of the three phases. The asymmetric phase is a fault phase, the symmetric phase is a normal phase, and the criterion is as follows:
n=1, 2..a., j phase and i phase of the n-th feeder are symmetrical phases;
n=1, 2..a., the j-phase or i-phase of the nth feeder is an asymmetric phase and the nth feeder is a faulty feeder. And further continuously judging symmetry degrees of other interphase of the feeder line, and screening out fault phases.
In one embodiment, the processor 105 may be configured to invoke a fault line selection procedure for the phase-asymmetry-based power distribution network stored in the memory 104, and perform the following operations:
and if the symmetry degree of the phase current is all greater than a setting value, determining that the target feeder is a sound feeder.
In one embodiment, the processor 105 may be configured to invoke a fault line selection procedure for the phase-asymmetry-based power distribution network stored in the memory 104, and perform the following operations:
acquiring a bus zero sequence voltage in the power distribution network;
determining whether the instantaneous value of the bus zero sequence voltage is larger than a preset voltage threshold value;
and when the instantaneous value of the bus zero sequence voltage is larger than the voltage threshold value, judging that the power distribution network is faulty, and executing the step of acquiring the pre-fault three-phase current value and the post-fault three-phase current value of the target feeder line.
Based on the hardware architecture of the fault line selection system of the power distribution network based on the power system technology, the embodiment of the fault line selection method of the power distribution network based on the phase asymmetry is provided.
Referring to fig. 2, fig. 2 is a simulation model of a power distribution network established based on PSCAD/EMTDC, and a total of 5 outgoing lines of a 110kV/10kV substation, wherein 3 feeder lines are overhead lines, l1=15km, l2=30km, l3=18km, 2 feeder lines are cables l4=6km, l5=8km, and the total of 5 feeder lines, the sampling frequency is 10kHz, and the set fault is a single-phase high-resistance ground fault. In the simulation example, the fault is set in the phase A of the feeder line 1, and the transition resistance is 2KΩ.
Referring to fig. 3, in a first embodiment, the fault line selection method for a power distribution network based on phase asymmetry includes the following steps:
step S10, when a power distribution network fails, acquiring a pre-failure three-phase current value and a post-failure three-phase current value of a target feeder line;
in this embodiment, the power distribution network is a high-ground power distribution network, and the high-ground power distribution network is characterized as a power distribution network with high resistance and low current, and each feeder line in the power distribution network has three phase currents. The power distribution network fault line selection system acquires a pre-fault three-phase current value and a post-fault three-phase current value of a target feeder line.
The three-phase current values before the fault are characterized as current values of three phases in the target feeder before the power distribution network fault occurs, and the three-phase current values after the fault are characterized as current values of three phases in the target feeder after the power distribution network fault occurs.
Alternatively, three current sensors are installed on a target feeder of the distribution network, the values of three phase currents are measured separately, and the current sensors are connected to a data acquisition system. The model and the installation position of the current sensor need to be selected and adjusted according to actual conditions so as to ensure accurate measurement of three-phase current values.
Step S20, three-phase current fault components of all feeder lines are obtained;
in this embodiment, after the pre-fault three-phase current value and the post-fault three-phase current value of the target feeder line are obtained, the pre-fault three-phase current value and the post-fault three-phase current value are subtracted to obtain a current difference value, and then the de-power frequency component three-phase current corresponding to the post-fault three-phase current of the feeder line is determined based on the current difference value.
Illustratively, the method of calculation is:。
wherein,in order to eliminate the three-phase current without the power frequency component after the power frequency component,as the three-phase current value before the failure,the three-phase current value after the fault.
Step S30, carrying out three-phase symmetry treatment to obtain three groups of symmetrical currents of the feeder line;
step S40, calculating symmetry degree rho among three groups of symmetrical currents;
and S50, determining a fault phase and a fault feeder line according to the symmetry degree.
In this embodiment, after the de-mains frequency component three-phase current is obtained, the phase current symmetry degree of the de-mains frequency component three-phase current is determined, and the phase current symmetry degree is characterized as a quantized value of whether the three phases of the de-mains frequency component three-phase current are symmetrical.
Specifically, the three phases of the three-phase current with the power frequency component removed are compared one by one, whether the three phases are symmetrical or not is judged, and the similarity of the phase currents is determined based on the symmetry or not.
Further, if the obtained symmetry degree of the phase current is smaller than a setting value, determining that the target feeder is a fault feeder.
In the technical scheme provided by the embodiment, the phase current symmetry degree of the three-phase current with the power frequency component removed is determined by calculating the current difference between the three-phase current value before the fault and the three-phase current value after the fault, the phase current symmetry degree is used as a line selection criterion, judgment can be timely made on a small-current power distribution network, and the line selection is accurate, so that the effect of improving the safety and stability of the system is achieved.
Further, in this embodiment, the step S10 includes:
step S11, filtering high-frequency transient components in the feeder line based on a preset filter;
step S12, extracting three-phase current values of preset periods before faults in the feeder lines after the high-frequency transient components are filtered out to serve as the three-phase current values before the faults, and three-phase current values of the preset periods after the faults are taken as the three-phase current values after the faults.
Optionally, in this embodiment, for how to obtain the three-phase current values before and after the fault, a low-pass filter is designed according to the characteristics and the preset period of the power distribution network, and the filter is applied to the current signals of each feeder line to filter out the high-frequency transient component. Specifically, a first-order or second-order butterworth filter may be employed, and the cutoff frequency may be set to the inverse of the preset period. Alternatively, the preset period may be four periods, or five periods.
Further, three current sensors are installed on each feeder line of the power distribution network, the values of three phase currents are measured respectively, and the current sensors are connected to a data acquisition system. The model and the installation position of the current sensor need to be selected and adjusted according to actual conditions so as to ensure accurate measurement of three-phase current values.
And acquiring three-phase current values of all feeder lines after filtering by a preset filter by using a data acquisition system, and storing the data in a computer or other storage equipment.
Extracting current values before and after the fault: according to the preset period, extracting three-phase current values of preset periods at intervals before faults from current data of all feeder lines to serve as the three-phase current values before the faults, and three-phase current values of the preset periods after the faults to serve as the three-phase current values after the faults.
In this embodiment, the current values before and after the fault with the same preset period interval are obtained after the high-frequency transient component in the feeder line is filtered out to be used as the three-phase current value before the fault and the three-phase current value after the fault respectively, so that judgment can be made in time for the distribution network with small current, and accurate line selection is achieved, thereby achieving the effect of improving the safety and stability of the system.
Further, in this embodiment, after the step S50, the method further includes:
and step S60, if the symmetry degree of the phase current is not less than a setting value, determining that the target feeder is a sound feeder.
In this embodiment, if the obtained symmetry degree of the phase current is not less than the setting value, the target feeder is determined to be a sound feeder. And then, selecting any feeder except the target feeder to execute the executing steps in the embodiment again until all feeders in the power distribution network perform one-time fault line selection judgment, thereby realizing fault line selection detection of the whole power distribution network.
Referring to fig. 4, in the second embodiment, based on any one of the embodiments, the step S30 includes:
step S31, determining a two-phase current difference value between the first phase current and the second phase current; and determining a two-three phase current difference between the second phase current and the third phase current; and determining a three-phase current difference between the first phase current and the third phase current;
alternatively, in the present embodiment, the de-mains frequency component three-phase current includes a first phase current, a second phase current, and a third phase current, the first phase current obtained by removing the mains frequency component currentCurrent of second phaseAnd a third phase currentAnd carrying out three-phase symmetry treatment and subtraction treatment between each two phases, wherein the time windows of the first phase current, the second phase current and the third phase current are the same, and four periodic waveforms are taken. Three groups of phase current data are obtained after each feeder line is processed through a first phase, a second phase, a first phase, a third phase and a second phase, and two-phase current difference values of the three groups of phase current data are obtained after each feeder line is processedDifference between two three-phase currentsAnd a three-phase current difference：
Referring to fig. 4, in the second embodiment, based on any one of the embodiments, the step S40 includes:
step S41, determining the symmetry degree of the phase currents according to the two-phase current difference value, the two-phase current difference value and the one-phase current difference value.
Referring to fig. 5 and 6, fig. 5 is a schematic diagram of a current waveform of a fault feeder after three-phase current subtraction, and fig. 6 is a schematic diagram of a current waveform of other normal feeder after three-phase current subtraction.
Further, the phase current symmetry degree of the target feeder line is determined according to the two-phase current difference value, the two-phase current difference value and the one-phase current difference value.
Wherein,andthe symmetry of (2) is:
based on the above equation, symmetry between each phase of each feeder line is calculated in turn.
Wherein,andthe symmetry of (2) is:
wherein,andthe symmetry of (2) is:
optionally, the step of determining the faulty phase and the faulty feeder according to the symmetry degree includes:
wherein, according to a two-phase current difference value, two three-phase current difference value and a three-phase current difference value, the step of determining the phase current symmetry degree of the target feeder line comprises:
step S411, if at least one of the two-phase current difference value, the two-phase current difference value and the three-phase current difference value is not null, setting the phase current symmetry degree as a first phase current symmetry degree;
in step S412, if the two-phase current difference value, and the three-phase current difference value are all null values, the phase current symmetry is set as the second phase current symmetry.
Optionally, in this embodiment, if at least one of the two-phase current difference value, and the three-phase current difference value is not null, the phase current symmetry is set as the first phase current symmetry;
and if the two-phase current difference value, the two-phase current difference value and the three-phase current difference value are all null values, setting the phase current symmetry degree as a second phase current symmetry degree.
The first phase current symmetry is a negative value, and the second phase current symmetry is a positive value.
In the technical scheme provided by the embodiment, the phase current difference values among the three phase currents are obtained by comparing the different phase currents, the symmetry degree of the phase currents is determined together according to the three phase current difference values, judgment can be timely made on a small-current power distribution network, and the line is accurately selected, so that the effect of improving the safety and stability of the system is achieved.
Further, in this embodiment, after step S41, the method further includes:
step S70, if the symmetry degree of the two-phase current difference is smaller than a setting value, determining that the first phase of the target feeder line is a fault phase;
step S80, if the symmetry degree of the two three-phase current difference is smaller than a setting value, determining that a second phase of the target feeder line is a fault phase;
step S90, if the symmetry degree of the three-phase current difference is smaller than the setting value, determining that the third phase of the target feeder is the fault phase.
Alternatively, in the present embodiment, for an object whose phase current symmetry is smaller than a setting value, the phase corresponding thereto is determined as the failed phase. Specifically, if the symmetry degree of the two-phase current difference is smaller than a setting value, determining that a first phase of the target feeder line is a fault phase; if the symmetry degree of the two three-phase current difference is smaller than the setting value, determining that the second phase of the target feeder line is a fault phase; and if the symmetry degree of the three-phase current difference values is smaller than the setting value, determining that the third phase of the target feeder line is a fault phase.
In the technical scheme provided by the embodiment, the fault phase in the fault feeder is judged through the phase current difference value, the specific fault position in the feeder is further selected and judged, the judgment can be timely made on the low-current power distribution network, the line is accurately selected, and therefore the effect of improving the safety and stability of the system is achieved.
Referring to fig. 7, in a third embodiment, before step S10, based on any embodiment, the method further includes:
step S100, acquiring bus zero sequence voltage in the power distribution network;
step S110, determining whether the instantaneous value of the zero sequence voltage of the bus is larger than a preset voltage threshold value;
and step S120, judging the power distribution network fault when the instantaneous value of the zero sequence voltage of the bus is larger than the voltage threshold value, and executing the step of acquiring the high-frequency transient component corresponding to the zero sequence current of the target feeder.
Optionally, in this embodiment, a bus zero sequence voltage sensor is provided in the power distribution network, and an instantaneous value of the bus zero sequence voltage is obtained by the sensor. Meanwhile, a voltage threshold detection module is arranged, and when the instantaneous value of the zero sequence voltage of the bus is larger than a preset phase voltage threshold, the module can send a power-on signal to the fault wave-recording line selection device.
The fault wave recording line selecting device is started after receiving the power-on signal, and starts to record the zero sequence voltage of each feeder line in a preset period after the fault occurs. During this period, the fault recording line selection device will transmit the recorded data to the upper computer for subsequent data analysis and processing.
It should be noted that, in order to ensure accuracy and stability of data, a high-precision voltage sensor should be selected, and the data should be reasonably filtered and corrected. In addition, the selection of the preset period should be adjusted according to specific conditions so as to fully ensure the integrity and accuracy of the data.
Illustratively, let the zero sequence voltage of the bus beA voltage threshold ofWherein, the method comprises the steps of, wherein,generally, the amount of the catalyst is 0.15,indicating the bus voltage rating.
If it isGreater thanAnd the fault line selection device is started immediately, and the zero sequence current of a cycle after the fault occurs is recorded.
In this embodiment, when the instantaneous value of the zero sequence voltage of the bus is greater than the preset phase voltage threshold, and the fault is primarily determined in the power distribution network, the fault wave recording line selection device is started to execute step S10, and when the power distribution network is faulty, the judgment and accurate line selection can be timely made, the detection accuracy is improved, and meanwhile, the safety and stability of the system are ensured in combination with the fault line selection method of the power distribution network based on phase asymmetry.
Furthermore, it will be appreciated by those of ordinary skill in the art that implementing all or part of the processes in the methods of the above embodiments may be accomplished by computer programs to instruct related hardware. The computer program comprises program instructions, and the computer program may be stored in a storage medium, which is a computer readable storage medium. The program instructions are executed by at least one processor in a fault line selection system of a power distribution network based on phase asymmetry to implement the flow steps of an embodiment of the method described above.
The present invention thus also provides a computer readable storage medium storing a phase-asymmetry-based power distribution network fault line selection program, which when executed by a processor, implements the steps of the phase-asymmetry-based power distribution network fault line selection method described in the above embodiments.
The computer readable storage medium may be a usb disk, a removable hard disk, a Read-Only Memory (ROM), a magnetic disk, or an optical disk, etc. which may store the program code.
It should be noted that, because the storage medium provided in the embodiments of the present application is a storage medium used to implement the method in the embodiments of the present application, based on the method described in the embodiments of the present application, a person skilled in the art can understand the specific structure and the modification of the storage medium, and therefore, the description thereof is omitted herein. All storage media used in the methods of the embodiments of the present application are within the scope of protection intended in the present application.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention 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 invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations 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. -
It should be noted that in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The use of the words first, second, third, etc. do not denote any order. These words may be interpreted as names.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (5)
1. The fault line selection method based on the phase asymmetry power distribution network is characterized by comprising the following steps of:
acquiring three-phase current fault components of each feeder line、/>、/>And performing three-phase symmetry treatment to obtain three groups of symmetric currents of the feeder line, which are +.>、/>、/>；
Calculating symmetry between three groups of symmetrical currents；
And determining a fault phase and a fault feeder line according to the symmetry degree.
2. The method of claim 1 wherein the acquiring three-phase current fault components for each feeder line、/>、And performing three-phase symmetry treatment to obtain three groups of symmetric currents of the feeder line, which are +.>、/>、/>The method comprises the following steps:
three groups of symmetrical currents for each feeder line、/>、/>The method comprises the following steps of:
；
；
；
wherein,、/>、/>the current data symmetrical about the phase current are retrieved after processing for each feeder line, respectively, < >>、/>、/>Each feeder A, B, C is a three-phase fault component.
3. The method of claim 1, wherein the degree of symmetry between three sets of symmetric currents is calculatedThe method comprises the following steps:
comparing the three-phase current data of each feeder line obtained after each two phases are subtracted, and calculating the symmetry degree of the three-phase currentObtaining whether A, B, C three phases of each feeder line are symmetrical;
wherein,and->The symmetry of (2) is:
；
in the method, in the process of the invention,is symmetrical and->The absolute value of (2) is 1 or less, (-)>A larger value indicates a higher degree of symmetry;
based on the above equation, symmetry between each phase of each feeder line is calculated in turn.
4. The method of claim 1, wherein the step of determining the faulty phase and faulty feeder based on the degree of symmetry comprises:
forming a system criterion according to the relativity of A, B, C three phases, judging whether the feeder line fails or not and which phase of A, B, C three phases fails according to the three-phase current symmetry;
the asymmetric phase is a fault phase, the symmetric phase is a normal phase, and the criterion is:
n=1, 2..a., j phase and i phase of the n-th feeder are symmetrical phases;
n=1, 2, meaning that the j phase or i phase of the nth feeder is an asymmetric phase and the nth feeder is a faulty feeder, further continuing to judge symmetry degrees of other phases of the feeder, and screening out the faulty phase;
wherein,the setting value of the symmetry degree is regulated according to the topological structure of the power distribution network and the operation condition.
5. A computer readable storage medium, characterized in that it has stored thereon a fault line selection program for a phase-asymmetric power distribution network, which when executed by a processor implements the steps of the fault line selection method for a phase-asymmetric power distribution network according to any of claims 1 to 4.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410161410.8A CN117706281A (en) | 2024-02-05 | 2024-02-05 | Fault line selection method, system and storage medium for power distribution network based on phase asymmetry |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410161410.8A CN117706281A (en) | 2024-02-05 | 2024-02-05 | Fault line selection method, system and storage medium for power distribution network based on phase asymmetry |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117706281A true CN117706281A (en) | 2024-03-15 |
Family
ID=90148283
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410161410.8A Pending CN117706281A (en) | 2024-02-05 | 2024-02-05 | Fault line selection method, system and storage medium for power distribution network based on phase asymmetry |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117706281A (en) |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103197203A (en) * | 2013-03-29 | 2013-07-10 | 昆明理工大学 | Fault line selection method based on time domain waveform correlation analysis of three-phase current breaking variable |
| CN103675605A (en) * | 2013-12-11 | 2014-03-26 | 湖南大学 | Small-current earth fault line selection method based on fault signal transient state correlation analysis |
| CN108490310A (en) * | 2018-03-21 | 2018-09-04 | 国网河南省电力公司漯河供电公司 | Method for small electric current grounding system of distribution network earth fault line selection |
| CN110133452A (en) * | 2019-07-01 | 2019-08-16 | 华北电力大学 | Mixed pressure based on waveform correlation coefficient and jump-value of current is the same as tower fault phase-selecting method |
| CN111208387A (en) * | 2020-02-17 | 2020-05-29 | 国电南瑞南京控制系统有限公司 | Distribution network single-phase grounding line selection method based on synchronous phase current fault component comparison |
| CN112485598A (en) * | 2020-12-04 | 2021-03-12 | 国网北京市电力公司 | Small current grounding fault positioning method combining waveform correlation and amplitude characteristics |
| CN114441891A (en) * | 2021-11-30 | 2022-05-06 | 国网辽宁省电力有限公司电力科学研究院 | Power distribution network single-phase earth fault line selection method based on current signal similarity |
-
2024
- 2024-02-05 CN CN202410161410.8A patent/CN117706281A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103197203A (en) * | 2013-03-29 | 2013-07-10 | 昆明理工大学 | Fault line selection method based on time domain waveform correlation analysis of three-phase current breaking variable |
| CN103675605A (en) * | 2013-12-11 | 2014-03-26 | 湖南大学 | Small-current earth fault line selection method based on fault signal transient state correlation analysis |
| CN108490310A (en) * | 2018-03-21 | 2018-09-04 | 国网河南省电力公司漯河供电公司 | Method for small electric current grounding system of distribution network earth fault line selection |
| CN110133452A (en) * | 2019-07-01 | 2019-08-16 | 华北电力大学 | Mixed pressure based on waveform correlation coefficient and jump-value of current is the same as tower fault phase-selecting method |
| CN111208387A (en) * | 2020-02-17 | 2020-05-29 | 国电南瑞南京控制系统有限公司 | Distribution network single-phase grounding line selection method based on synchronous phase current fault component comparison |
| CN112485598A (en) * | 2020-12-04 | 2021-03-12 | 国网北京市电力公司 | Small current grounding fault positioning method combining waveform correlation and amplitude characteristics |
| CN114441891A (en) * | 2021-11-30 | 2022-05-06 | 国网辽宁省电力有限公司电力科学研究院 | Power distribution network single-phase earth fault line selection method based on current signal similarity |
Non-Patent Citations (3)
| Title |
|---|
| 刘谋海 等: "基于暂态相电流特征分析的故障选线新方法", 电力系统及其自动化学报, no. 01, 15 January 2017 (2017-01-15), pages 34 - 40 * |
| 戴栩生 等: "基于暂态相关性分析的小电流接地故障选线方法", 中国电力, no. 01, 5 January 2015 (2015-01-05), pages 90 - 95 * |
| 杨尚瑾 等: "基于相电流差的短路故障快速识别方法", 电网技术, vol. 44, no. 6, 30 June 2020 (2020-06-30), pages 2330 - 2335 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109444640B (en) | Power distribution network single-phase high-resistance earth fault detection method, system and storage medium | |
| CN108957244B (en) | Single-phase earth fault line selection positioning method for distribution network main station | |
| Aggarwal et al. | New concept in fault location for overhead distribution systems using superimposed components | |
| WO1998029752A9 (en) | System for locating faults and estimating fault resistance in distribution networks with tapped loads | |
| WO1998029752A1 (en) | System for locating faults and estimating fault resistance in distribution networks with tapped loads | |
| CN111812451B (en) | Phase current transient fault component-based distributed line selection method for power distribution network | |
| CN110954743B (en) | Distributed wave recording device and low-current grounding line selection method | |
| CN108562820B (en) | Single-phase earth fault line selection method and device for small current grounding system | |
| CN109283431B (en) | Power distribution network fault section positioning method based on limited PMU | |
| CN111426908B (en) | Single-phase earth fault protection method, device and system for small current earthing system | |
| CN113391164A (en) | Intelligent identification method and device for single-phase earth fault of power distribution network | |
| CN110045232B (en) | Method for identifying ground fault phase of neutral point non-effective grounding system | |
| Devadasu et al. | A novel multiple fault identification with fast fourier transform analysis | |
| CN111398871A (en) | Device and method for checking polarity of zero sequence current transformer | |
| CN107179476B (en) | Distribution network fault distance measurement method | |
| CN112379302B (en) | Small-current ground fault protection method, device and system for integrating time-frequency domain information | |
| JP7437584B2 (en) | Machine learning-based method and apparatus for power line disturbance classification | |
| CN112485595B (en) | Power distribution network ground fault line selection protection method and device | |
| CN112485716B (en) | Line selection method based on zero-rest transient characteristic signal of ground fault arc current | |
| CN106646138B (en) | Distribution net work earthing fault localization method based on the conversion of more sample frequency wavelet character energy | |
| CN117706281A (en) | Fault line selection method, system and storage medium for power distribution network based on phase asymmetry | |
| CN114200354B (en) | Zero sequence CT polarity online detection method, system and equipment | |
| CN113608069B (en) | Direct-current power distribution network ground fault identification method and system of MMC injected detection signal | |
| CN112578228A (en) | Zero-sequence-independent single-phase earth fault discrimination algorithm for power distribution network | |
| CN113064025B (en) | Ground fault line selection tripping method and system in resonance grounding system |
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 |