CN109085450B - Fault phase selection method and device for low-current grounding system - Google Patents
Fault phase selection method and device for low-current grounding system Download PDFInfo
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- 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
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
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Abstract
The invention is suitable for the technical field of distribution network fault detection, and provides a fault phase selection method and a fault phase selection device for a low-current grounding system, wherein the method comprises the following steps: acquiring zero sequence voltage and each phase-to-ground voltage of the small current grounding system, and acquiring the state of the small current grounding system according to the zero sequence voltage; when the state of the low-current grounding system is in a grounding fault state, determining a voltage mutation information value sequence according to each phase-to-ground voltage; the method determines the phase of the ground fault according to the voltage mutation information value sequence, judges the phase of the ground fault by adopting the voltage mutation information value sequence, can eliminate the influence of the voltage unbalance of each line on the detection result by adopting the voltage mutation information value, and has the characteristic of high transmission speed by adopting the voltage mutation information value, so the method has the advantages of accurate identification result and high judgment speed.
Description
Technical Field
The invention belongs to the technical field of distribution network fault detection, and particularly relates to a fault phase selection method and device for a low-current grounding system.
Background
The small current grounding system is a system with a neutral point not grounded or an arc suppression coil grounded, when the small current grounding system has a single-phase grounding fault, the grounding current is small, the power supply of the system cannot be interrupted, and meanwhile, due to the existence of the grounding fault, the invisible fault exists in a circuit, so that the transmission of electric power and the safety of a power grid are influenced. For example, the following examples: when the grounding system adopts a neutral point non-grounding mode and has a grounding fault, system overvoltage easily occurs and interphase short circuit expansion accidents are caused; when the grounding system adopts an arc suppression coil grounding mode and has grounding fault, the problems that personal potential safety hazard is large, the arc suppression coil cannot operate when the capacitance current is large and the like exist. Therefore, timely determination of the fault line of the low-current grounding system is important for the safety of the power grid.
According to the existing fault phase selection method for the small-current grounding system, after a single-phase grounding fault occurs, the voltage of a fault line is reduced, and the voltage of a non-fault line is increased, so that the line with low voltage is simply considered as the fault line, and the fault phase selection method has high false alarm rate.
Disclosure of Invention
In view of this, the present invention provides a small current grounding system fault phase selection method and apparatus, so as to solve the problem that the small current grounding system fault phase selection method in the prior art has a higher false alarm rate.
The first aspect of the embodiment of the invention provides a fault phase selection method for a low-current grounding system, which comprises the following steps:
acquiring zero sequence voltage and each phase-to-ground voltage of the small current grounding system, and acquiring the state of the small current grounding system according to the zero sequence voltage; the states of the grounding system include: in a ground fault state and not in a ground fault state;
when the state of the small current grounding system is in a grounding fault state, determining a voltage abrupt change information value sequence according to each phase-to-ground voltage;
and determining the phase of the ground fault according to the voltage mutation information value sequence.
A second aspect of the embodiments of the present invention provides a small-current grounding system fault phase selection apparatus, including: the system comprises a data acquisition unit, a state acquisition unit, a mutation amount calculation unit and a fault phase judgment unit;
the data acquisition unit is used for acquiring zero sequence voltage and each phase-to-ground voltage of the small current grounding system;
the state acquisition unit is used for acquiring the state of the small current grounding system according to the zero sequence voltage; the states of the grounding system include: in a ground fault state and not in a ground fault state;
the abrupt change amount calculation unit is used for determining a voltage abrupt change amount information value sequence according to each phase-to-ground voltage when the state of the low-current grounding system is in a grounding fault state;
and the fault phase judging unit is used for determining the phase of the ground fault according to the voltage mutation information value sequence.
A third aspect of an embodiment of the present invention provides a terminal device, including: the fault phase selection method comprises a memory, a processor and a computer program which is stored in the memory and can run on the processor, wherein the processor executes the computer program to realize the steps of the fault phase selection method of the low-current grounding system.
A fourth aspect of the embodiments of the present invention provides a computer-readable storage medium, where the computer program, when executed by a processor, implements the steps of the low-current grounding system fault phase selection method as described in any one of the above.
Compared with the prior art, the embodiment of the invention has the following beneficial effects: the method comprises the steps of judging the state of the small current grounding system by acquiring zero sequence voltage of the small current grounding system, determining a voltage sudden change information value according to each acquired phase-to-ground voltage when the small current grounding system is in a ground fault state, finally determining the phase of the ground fault according to the acquired voltage sudden change information value, and taking the voltage sudden change information value as a judgment basis of the small current ground fault phase.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the embodiments or drawings used in the prior art description, and obviously, the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic flow chart illustrating an implementation process of a phase selection method for a low-current grounding system fault according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of an implementation of step S101 in fig. 1 according to an embodiment of the present invention;
fig. 3 is a schematic flow chart of an implementation of step S102 in fig. 1 according to an embodiment of the present invention;
fig. 4 is a schematic flow chart of an implementation of step S301 in fig. 3 according to an embodiment of the present invention;
fig. 5 is a schematic flow chart of an implementation of another phase selection method for a low-current grounding system fault according to an embodiment of the present invention;
FIG. 6 is two A-phase incomplete grounding vector diagrams provided by the embodiment of the present invention;
fig. 7 is a schematic flow chart of an implementation of a phase selection method for a low-current grounding system fault according to another embodiment of the present invention;
fig. 8 is a schematic structural diagram of a small-current grounding system fault phase selection device provided in an embodiment of the present invention;
fig. 9 is a schematic diagram of a terminal device according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
In order to explain the technical means of the present invention, the following description will be given by way of specific examples.
Fig. 1 shows a schematic implementation flow diagram of a phase selection method for a low-current grounding system fault provided by an embodiment of the present invention, which is detailed as follows:
step S101, acquiring zero sequence voltage and phase-to-ground voltage of the small current grounding system, and acquiring the state of the small current grounding system according to the zero sequence voltage; the states of the grounding system include: in a ground fault state and not in a ground fault state.
In this embodiment, the zero sequence voltage of the small current grounding system is a voltage component obtained when the voltage and current of the system are asymmetric, and when the system fails, the state of the system can be obtained by detecting the zero sequence component of the system. The method for acquiring the zero sequence voltage may be as follows: and connecting the secondary side of the three-phase voltage transformer into an open triangle form, wherein the measured open triangle voltage is zero sequence voltage. After the zero sequence voltage is obtained, judging the state of the grounding system according to the magnitude of the zero sequence voltage, wherein the state of the grounding system comprises a state of being in a grounding fault and a state of not being in the grounding fault.
And S102, when the state of the low-current grounding system is in a grounding fault state, determining a voltage abrupt change information value sequence according to each relative ground voltage.
In the present embodiment, when the low-current grounding system is in the ground fault state, it is necessary to determine the fault phase of the low-current grounding system. Specifically, the present embodiment determines the fault phase of the ground system by the voltage transient information value sequence. Wherein the sequence of voltage transient information values is obtained from the respective relative ground voltages of the grounding system. The fault phase of the grounding system can be reflected through the quantity relation of different numerical values in the voltage break variable information value sequence.
The adoption of the voltage mutation information value sequence as the judgment basis of the fault phase has the following advantages: first, compared with the conventional analog quantity adopted for judgment, the method has the characteristics of high transmission speed and less occupied storage space by adopting the voltage break variable information value sequence, so that the detection speed is higher. Secondly, the method comprises the following steps: the influence of voltage unbalance on amplitude comparison can be eliminated by adopting the voltage sudden change information value, the influence of voltage value fluctuation is small, and the detection result has high stability.
And step S103, determining a ground fault phase according to the voltage mutation information value sequence.
In this embodiment, the ground fault phase can be determined after the voltage jump amount information value is acquired. And determining the ground fault phase according to the number of different values in the voltage mutation quantity information value. Specifically, when the earth fault phase is judged, the judgment is performed according to a preset fault judgment expert library, wherein the fault judgment expert library stores corresponding relations between different voltage break variable information values and the fault phase, and after the voltage break variable information values are obtained, the earth fault phase can be output according to the voltage break variable information values.
It can be known from the above embodiments that the state of the small current grounding system is determined by obtaining the zero sequence voltage of the small current grounding system, and when the small current grounding system is in the ground fault state, the voltage break variable information value is determined according to the obtained voltages to ground, and finally the phase with the ground fault is determined according to the obtained voltage break variable information value.
As shown in fig. 2, in an embodiment of the present invention, fig. 2 shows a specific implementation flow of step S101 in fig. 1, and a process thereof is detailed as follows:
step S201, determining a magnitude relationship between the zero-sequence voltage and the zero-sequence voltage threshold.
Step S202, if the zero sequence voltage is larger than the zero sequence voltage threshold value, the low current grounding system is in a grounding fault state.
In this embodiment, it is necessary to determine that the grounding system is in a ground fault state before determining the ground fault phase. When the small current grounding system is not in a grounding fault state, namely when the small current grounding system operates normally, theoretically, the zero sequence voltage 3U on the side of the system bus0Equal to 0, but in practical operation, the zero sequence voltage is 3U in consideration of the influence of various factors0It will be greater than 0 but much less than the zero sequence voltage threshold. However, when the low-current grounding system is in a ground fault state, a significant zero-sequence component, namely, a zero-sequence voltage of 3U, occurs0Will be greater than the zero sequence voltage threshold. Therefore, the state of the small current grounding system can be judged by detecting the magnitude relation between the zero sequence voltage and the zero sequence voltage threshold value.
In addition, after the low-current grounding system is detected to be in a grounding fault state, whether the in-station switch is tripped or not needs to be judged. This is because, when a ground fault occurs under normal conditions, the generated ground fault current is small, and because the system adopts overcurrent protection and a trip state cannot occur, the system is in a potential dangerous state, and if a switch in a station trips, judgment of fault phase selection is not needed, and potential harm cannot occur after power failure. Therefore, after the line is determined to be in the ground fault state, the trip state of the in-station switch is further judged, so as to determine whether to start the fault phase selection program.
In this embodiment, the ground fault state of the ground system is determined by pre-determining the magnitude relationship between the zero-sequence voltage and the zero-sequence voltage threshold, so as to ensure that the fault phase is determined by the fault phase selection method when the system is in the ground fault state. Further, in order to ensure reasonable implementation of the fault phase selection method, the trip state of the in-station switch is also determined, and the fault phase can be determined by the fault phase selection method only when the ground fault occurs and the in-station switch does not trip, otherwise, the system is in a power-down state, and the fault phase selection method cannot work normally.
As shown in fig. 3, in an embodiment of the present invention, fig. 3 shows a specific implementation flow of step S102 in fig. 1, and the process thereof is detailed as follows:
step S301, acquiring information values of sudden change quantities of voltages of each phase according to voltages of each phase to ground; the relative ground voltages comprise an effective value of the ground voltage before the fault and an effective value of the ground voltage after the fault.
Step S302, determining a voltage mutation amount information value sequence according to the voltage mutation amount information values of each phase.
In the present embodiment, after acquiring the respective phase-to-ground voltages, the voltage discontinuity information value may be acquired from the respective phase-to-ground voltages. The voltage sudden change information value is obtained by quantifying a change value between the ground voltage effective value before the fault and the ground voltage effective value after the fault. Wherein the acquired voltage sudden change amount information value is a voltage sudden change amount information value of each phase. In order to judge the ground fault phase of the system, it is necessary to integrate the three-phase voltage sudden change information values for judgment, specifically, the voltage sudden change information values of each phase may be combined in the order of the a-phase, the B-phase and the C-phase to obtain a voltage sudden change information value sequence.
Through the embodiment, compared with a method directly adopting the voltage value, the method adopting the voltage mutation quantity information value sequence has higher stability, so that the detection result also has higher stability.
As shown in fig. 4, in an embodiment of the present invention, fig. 4 shows a specific implementation flow of step S301 in fig. 3, and a process thereof is detailed as follows:
step S401, determining a voltage break variable according to the post-fault voltage effective value and the pre-fault voltage effective value.
Step S402, judging the size relation between the voltage sudden-change quantity and the preset voltage sudden-change quantity, and determining the information value of the voltage sudden-change quantity according to the size relation between the voltage sudden-change quantity and the preset voltage sudden-change quantity.
In this embodiment, the process of acquiring the voltage abrupt change amount information value according to each phase-to-ground voltage is as follows: firstly, determining a voltage break variable according to a voltage effective value before a fault and a voltage effective value after the fault, wherein U is definedtIs an effective value of the voltage after the fault, Ut' if the effective value of the voltage before the fault and the delta U are abrupt voltage changes, the formula delta U is equal to Ut-Ut' calculating a post-fault voltage effective value minus a pre-fault voltage effective value, thereby determining a resulting voltage difference as a voltage break amount. After the voltage transient is obtained, the voltage transient information value may be determined according to the value of the voltage transient, and specifically, the voltage transient information value may be determined according to a size relationship between the voltage transient and a preset voltage transient. For example: the preset voltage sudden change amount can be selected to be 0, and when the voltage sudden change amount is less than or equal to 0, the voltage sudden change amount information value is a first numerical value, and the first numerical value can be 0; when the voltage sudden change amount is greater than 0, the voltage sudden change amount information value is a second value, and the second value may be 1.
Through the embodiment, the voltage mutation amount information value can be determined according to the size relation between the voltage mutation amount and the preset voltage mutation amount, the voltage mutation amount information value can reflect the voltage change before and after the fault, and therefore the voltage mutation amount information value sequence determined according to the voltage mutation amount information values of three phases can reflect the fault change of three phases.
As shown in fig. 5, in an embodiment of the present invention, before step S103, an embodiment of the present invention further includes:
and step S501, acquiring a voltage mutation amount information value sequence once every preset time.
Step S502, obtaining the continuous occurrence times of the same voltage mutation quantity information value sequence.
And step S503, when the occurrence times of the same mutation quantity information value sequence are more than the preset times, determining the ground fault phase according to the voltage mutation quantity information value sequence.
In the present embodiment, it is also necessary to eliminate the case where the acquired data is accidental before the ground fault phase is determined from the sequence of voltage discontinuity information values. This is because, if the faulty phase is determined based on the voltage variation information value sequence acquired at one time, the data selected at that time may have contingency and the faulty phase cannot be accurately determined. Therefore, the voltage mutation amount information value sequence can be obtained for multiple times, and when the voltage mutation amount information value sequences obtained each time are the same, the fault phase is determined according to the voltage mutation amount information value sequence.
Specifically, the method may be: when the system is still in a ground fault state, acquiring a voltage mutation information value sequence at intervals, for example: the period of time can be 0.5 second, the continuous occurrence times of the same voltage mutation information value sequence are obtained, and when the voltage mutation information value sequences obtained by the continuous preset times are the same, the obtained voltage mutation information value sequence is a stable sequence and can be used as a basis for judging a fault phase. For example: the preset times can be five times, when the continuous occurrence times of the voltage mutation quantity information value sequence is five times, the voltage mutation quantity information value sequence is considered to be a stable sequence, otherwise, the voltage mutation quantity information value sequence is obtained again and counting is carried out again.
Through the embodiment, the voltage mutation amount information value sequence adopted by the method does not depend on the voltage mutation amount information value sequence obtained at one time, the voltage mutation amount information value sequence is obtained for multiple times, and the fault phase is judged when the voltage mutation amount information value sequences obtained for multiple times are the same.
In one embodiment, the determining the ground fault phase according to the voltage jump information value sequence in step S103 specifically includes:
directly determining a ground fault phase according to the voltage mutation information value sequence; or, determining the grounding fault phase according to the voltage break variable information value sequence and the neutral point grounding mode information value.
In this embodiment, after the voltage discontinuity information value is obtained, the ground fault phase may be directly determined according to the quantity relationship between the first value and the second value in the voltage discontinuity information value, or when the ground fault phase cannot be determined according to the quantity relationship between the first value and the second value, the ground fault phase may be determined by combining the neutral point grounding mode information value. The neutral point grounding mode information value is determined according to the grounding mode of the system, and when the grounding mode of the system is a neutral point ungrounded mode or arc suppression coil undercompensation grounding mode, the neutral point grounding mode information value is a second numerical value; when the grounding mode of the system is arc suppression coil overcompensation grounding, the information value of the neutral point grounding mode is a first numerical value. Wherein the first value can be represented as 0 and the second value can be represented as 1.
Through the embodiment, the influence of the grounding mode of the grounding system on the fault phase is fully considered as the basis of the information value of the grounding mode of the neutral point, so that the method can not be influenced by the grounding mode of the system, namely, the method can be used for determining the grounding fault phase no matter the grounding mode of the neutral point, the under-compensation mode and the over-compensation mode of the arc suppression coil.
In one embodiment, the ground fault phase is directly determined according to the voltage mutation information value sequence; or, determining the ground fault phase according to the voltage abrupt change information value sequence and the neutral point grounding mode information value, specifically including:
when only one phase information value in the mutation quantity information value sequence is a first numerical value, the phase corresponding to the first numerical value is a ground fault phase;
when only one phase information value in the mutation quantity information value sequence is a second numerical value, acquiring a neutral point grounding mode information value, and when the neutral point grounding mode information value is a first numerical value, the left phase of the corresponding phase of the second numerical value is a grounding fault phase; and when the neutral point grounding mode information value is a second value, the right phase of the phase corresponding to the second value is a grounding fault phase.
In the above embodiment, the specific method for determining the ground fault phase according to the abrupt change amount information value is as follows: and determining the number of first numerical values in the mutation quantity information values according to the obtained mutation quantity information values, and when only one phase in the mutation quantity information values is the first numerical value, directly determining a grounding fault phase which is a phase corresponding to the first numerical value. When only one phase in the mutation quantity information values is the second numerical value, judging by further combining a neutral point grounding mode, and when the grounding mode of the neutral point is the first numerical value, the left side phase of the phase corresponding to the second numerical value is a fault phase, wherein the judged sequence is the circulating sequence of the A phase, the B phase and the C phase; when the grounding mode of the neutral point is a second value, the right side phase of the phase is a fault phase according to the second value.
For example: when the obtained mutation amount information value is one of 011, 101 and 110, the fault phase can be directly judged to be an A phase, a B phase and a C phase respectively; when the obtained mutation amount information value is one of 001, 100 and 010, the fault phase cannot be directly determined, a neutral point information value needs to be obtained, and the fault phase is determined according to a phase selection information value sequence formed by the neutral point information value and the mutation amount information value. Specifically, when the neutral point information value is 1, the phase selection information value sequence is 1001, 1100 and 1010 in sequence, and the failed phase can be judged to be a phase A, a phase B and a phase C in sequence; when the neutral point information value is 0, the phase selection information value sequence is 0001, 0100 and 0010 in sequence, and the failed phase can be judged to be a phase B, a phase C and a phase A in sequence. And outputting an alarm signal when the obtained other mutation information values are illegal sequences.
The above-mentioned judging method is obtained by collecting the variable voltages of different phase lines in different grounding modes after determining the grounding fault, refer to fig. 6, which shows the vector diagram of the grounding fault of phase a in two grounding modes of the system, the left side of fig. 6 is the vector diagram of the under-compensated state of the neutral point ungrounded or the arc suppression coil grounded, and the right side of fig. 6 is the vector diagram of the over-compensated state of the arc suppression coil grounded.
See left drawing, U of FIG. 6NdIs a phase voltage U of a ground phaseAVoltage to ground U of A, B, C after fault, which is a semicircle of diameter on one side of its clockwise needleAd、UBd、UCdWill change continuously with the change of the grounding resistance, R in the figuregIs the critical point of the grounding resistance, when the grounding resistance value R<RgTime, Delta UAd<0、 ΔUBd>0、ΔUCd>0, the abrupt change information values are 0, 1 and 1 respectively, and when the grounding resistance value R is equal to RgTime, Delta UAd<0、 ΔUBd＝0、ΔUCd>0, mutation amount information values are respectively 0, 0 and 1; when the ground resistance value R>RgTime, Delta UAd<0、 ΔUBd<0、ΔUCd>0, and mutation amount information values of 0, 0 and 1, respectively.
Referring to the right diagram of FIG. 6, voltage to ground U of A, B, C after faultAd、UBd、UCdWill change continuously along with the change of the grounding resistance, R'gIs the critical point of the grounding resistance, when the grounding resistance value R<R'gTime, Delta UAd<0、 ΔUBd>0、ΔUCd>0, the abrupt change information values are 0, 1 and 1 respectively, and when the grounding resistance value R is equal to RgTime, Delta UAd<0、 ΔUBd>0、ΔUCdThe mutation amount information values are 0, 1 and 0, respectively; when the ground resistance value R>R'gTime, Delta UAd<0、 ΔUBd>0、ΔUCd<0, and mutation amount information values of 0, 1 and 0, respectively.
According to the fact that the fault phases in the above conditions are all the A phases, the judgment basis of the method can be obtained. Through the embodiment, the influence of the compensation mode of the arc suppression coil on the grounding fault phase is fully considered, so that the obtained result is more accurate, and the adaptability is wider.
It can be known from the above embodiments that the state of the small current grounding system is determined by obtaining the zero sequence voltage of the small current grounding system, and when the small current grounding system is in the ground fault state, the voltage break variable information value is determined according to the obtained voltages to ground, and finally the phase with the ground fault is determined according to the obtained voltage break variable information value. In addition, the influence of a compensation mode on a fault phase in an arc suppression coil grounding mode is considered, so that the method is more accurate in obtained result and stronger in adaptability. Meanwhile, the adopted mutation information value is an information value which continuously appears for many times, so that the reliability of the obtained result is higher.
Fig. 7 shows a schematic flow chart of an implementation of another small-current grounding system fault phase selection method according to an embodiment of the present invention, which is detailed as follows:
step S101, obtaining zero sequence voltage 3U0；
Step S102, judging zero sequence voltage 3U0With zero sequence voltage threshold value UrThe size relationship between the two is 3U0>UrIf not, executing step S103, otherwise, executing step S102;
step S103, judging whether the switch in the station trips or not, and finishing operation after the switch trips; otherwise, executing step S104;
step S104, starting a current phase program;
step S105, setting i and assigning an initial value 1 to i; i is used for acquiring the information value sequence of the voltage break variable of two adjacent times;
step S106, collecting and calculating voltage break variables delta Ua and delta Ub、ΔUc；
Step S107, calculating a mutation quantity information value sequence Li according to the voltage mutation quantity;
step S108, judging whether the obtained voltage mutation quantity information value sequence is legal, and executing step S111 when the sequence is legal; otherwise, executing step S109;
step S109, setting a j value, assigning an initial value 1 to the j value, and setting a range of the j value; j is used to count the number of illegal times of the sequence; when the value of j is smaller than the set range value, executing step S106, otherwise executing step S110;
step S110, sending out alarm information;
step S111, judging whether i-1 is equal to 0, if i-1 is equal to 0, delaying for 0.5 seconds, executing step S105 to obtain the mutation information value sequence Li again, otherwise executing step S112;
step S112, judging whether the mutation amount information value sequences Li and Li-1 obtained twice are the same, if so, executing step S114, otherwise, executing step S113;
step S113, setting a value m, assigning an initial value 1 to the value m, and setting a range of the value m; m is used for judging the times of different mutation quantity information value sequences obtained twice, and step S104 is executed when m meets the condition, otherwise step S110 is executed;
step S114, setting the numerical range of i, executing step S105 when i meets the condition, otherwise executing step S115;
step S115, determining that the mutation quantity sequence is Li;
step S116, acquiring a neutral point information value;
step S117, determining a phase selection information value sequence according to the mutation quantity sequence and the neutral point information value;
step S118, determining and outputting a phase selection result according to the phase selection information value sequence;
step S119 ends.
It can be known from the above embodiments that the state of the small current grounding system is determined by obtaining the zero sequence voltage of the small current grounding system, and when the small current grounding system is in the ground fault state, the voltage break variable information value is determined according to the obtained voltages of the phases to ground, and finally the phase with ground fault is determined according to the obtained voltage break variable information value.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
As shown in fig. 8, a schematic structural diagram of a small-current grounding system fault phase selection device provided by an embodiment of the present invention is shown, and details are as follows:
the small-current grounding system fault phase selection device comprises a data acquisition unit 101, a state acquisition unit 102, a mutation amount calculation unit 103 and a fault phase judgment unit 104.
The data acquisition unit 101 is configured to acquire zero sequence voltage and each relative ground voltage of the low-current grounding system.
The state obtaining unit 102 is configured to obtain a state of the low-current grounding system according to the zero-sequence voltage; the states of the grounding system include: in a ground fault state and not in a ground fault state.
The abrupt change amount calculation unit 103 is configured to determine a sequence of voltage abrupt change amount information values according to the respective phase-to-ground voltages when the state of the low-current grounding system is in a ground fault state.
And the fault phase judging unit 104 is configured to determine a ground fault phase according to the voltage jump information value sequence.
In an embodiment of the present invention, the mutation amount calculation unit 103 provided in the embodiment of the present invention further includes: a mutation amount information value acquisition subunit and a mutation amount information value sequence acquisition subunit;
the abrupt change information value acquisition subunit is used for acquiring an abrupt change information value of each phase voltage according to each phase-to-ground voltage; the ground-to-ground voltages comprise an effective value of ground-to-ground voltage before fault and an effective value of ground-to-ground voltage after fault.
And the mutation quantity information value sequence obtaining subunit is used for determining the voltage mutation quantity information value sequence according to the mutation quantity information values of the voltages of the phases.
In an embodiment of the present invention, an apparatus provided in an embodiment of the present invention further includes: the device comprises a time unit, a counting unit and a judging unit;
and the time unit is used for acquiring the voltage mutation information value sequence once every preset time.
And the counting unit acquires the continuous occurrence times of the same voltage mutation information value sequence.
And the judging unit is used for determining the ground fault phase according to the voltage mutation information value sequence when the occurrence frequency of the same mutation information value sequence is greater than the preset frequency.
It can be known from the above embodiments that the zero sequence voltage of the small current grounding system is acquired by the data acquisition unit, the state of the small current grounding system is acquired by the state acquisition unit, when the small current grounding system is in a ground fault state, the voltage sudden change information value is determined according to each phase-to-ground voltage by the sudden change calculation unit, and the ground fault phase is determined according to the acquired voltage sudden change information value by the fault phase determination unit.
Fig. 9 is a schematic diagram of a terminal device according to an embodiment of the present invention. As shown in fig. 9, the terminal device 90 of this embodiment includes: a processor 900, a memory 901 and a computer program 902 stored in said memory 901 and executable on said processor 900, for example a ground fault phase program determined from a sequence of voltage step change information values. The processor 900 executes the computer program 902 to implement the steps in the above-mentioned embodiments of the low-current grounding system fault phase selection method, such as the steps S101 to S103 shown in fig. 1. Alternatively, the processor 900 implements the functions of the modules/units in the above-mentioned device embodiments, for example, the functions of the units 101 to 104 shown in fig. 8, when executing the computer program 902.
Illustratively, the computer program 902 may be partitioned into one or more modules/units that are stored in the memory 901 and executed by the processor 900 to implement the present invention. The one or more modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution of the computer program 902 in the terminal device 90. For example, the computer program 902 may be divided into a data acquisition unit, a state acquisition unit, a mutation amount calculation unit, and a failure phase determination unit, where the specific functions of each unit are as follows:
the data acquisition unit is used for acquiring zero sequence voltage and each phase-to-ground voltage of the small current grounding system;
the state acquisition unit is used for acquiring the state of the small current grounding system according to the zero sequence voltage; the states of the grounding system include: in a ground fault state and not in a ground fault state;
the abrupt change amount calculation unit is used for determining a voltage abrupt change amount information value sequence according to each phase-to-ground voltage when the state of the low-current grounding system is in a grounding fault state;
the fault phase judging unit is used for determining a ground fault phase according to the voltage mutation information value sequence
The terminal device 90 may be a desktop computer, a notebook, a palm computer, a cloud server, or other computing devices. The terminal device may include, but is not limited to, a processor 900, a memory 901. Those skilled in the art will appreciate that fig. 9 is merely an example of a terminal device 90 and does not constitute a limitation of the terminal device 90 and may include more or fewer components than shown, or some components may be combined, or different components, e.g., the terminal device may also include input-output devices, network access devices, buses, etc.
The Processor 900 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The storage 901 may be an internal storage unit of the terminal device 90, such as a hard disk or a memory of the terminal device 90. The memory 901 may also be an external storage device of the terminal device 90, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like, which are provided on the terminal device 90. Further, the memory 901 may also include both an internal storage unit and an external storage device of the terminal device 90. The memory 901 is used for storing the computer program and other programs and data required by the terminal device. The memory 901 may also be used to temporarily store data that has been output or is to be output.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned functional units and modules are illustrated as being divided, and in practical applications, the above-mentioned functions may be distributed as different functional units and modules according to needs, that is, the internal structure of the apparatus may be divided into different functional units or modules to complete all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit, and the integrated unit may be implemented in the form of a hardware or a software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. For the specific working processes of the units and modules in the system, reference may be made to the corresponding processes in the foregoing method embodiments, which are not described herein again.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described or recited in detail in a certain embodiment, reference may be made to the descriptions of other embodiments.
Those of ordinary skill in the art would appreciate that the elements and algorithm steps of the various embodiments described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal device and method may be implemented in other ways. For example, the above-described terminal device embodiments are merely illustrative, and for example, the division of the modules or units is only one logical function division, and there may be other divisions when the actual implementation is performed, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, all or part of the processes in the method according to the embodiments of the present invention may also be implemented by instructing related hardware through a computer program, which may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the method embodiments may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, and software distribution medium, etc. It should be noted that the computer readable medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media may not include electrical carrier signals and telecommunications signals in accordance with legislation and patent practice.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the present invention, and are intended to be included within the scope thereof.
Claims (8)
1. A fault phase selection method for a low-current grounding system is characterized by comprising the following steps:
acquiring zero sequence voltage and each phase-to-ground voltage of the small current grounding system, and acquiring the state of the small current grounding system according to the zero sequence voltage; the states of the grounding system include: in a ground fault state and not in a ground fault state;
when the state of the low-current grounding system is in a grounding fault state, determining a voltage mutation information value sequence according to each phase-to-ground voltage;
determining the phase of the ground fault according to the voltage mutation information value sequence;
when only one phase information value in the mutation quantity information value sequence is a first numerical value, the phase corresponding to the first numerical value is a ground fault phase;
when only one phase information value in the mutation quantity information value sequence is a second numerical value, acquiring a neutral point grounding mode information value; the neutral point grounding mode information value is determined according to the grounding mode of the system, and when the grounding mode of the system is a neutral point ungrounded mode or arc suppression coil under-compensation grounding mode, the neutral point grounding mode information value is a second numerical value; when the grounding mode of the system is arc suppression coil overcompensation grounding, the information value of the neutral point grounding mode is a first numerical value; the first numerical value is represented by 0 and the second numerical value is represented by 1;
when the neutral point grounding mode information value is a first numerical value, the left phase of the line corresponding to the second numerical value is a ground fault phase; when the neutral point grounding mode information value is a second numerical value, the right phase of the line corresponding to the second numerical value is a ground fault phase; wherein, the judged sequence is the circulating sequence of the A phase, the B phase and the C phase.
2. The small-current grounding system fault phase selection method according to claim 1, wherein the obtaining the state of the small-current grounding system according to the zero sequence voltage specifically comprises:
judging the magnitude relation between the zero sequence voltage and the zero sequence voltage threshold value;
and if the zero sequence voltage is greater than the zero sequence voltage threshold value, the small current grounding system is in a grounding fault state.
3. The small-current grounding system fault phase selection method according to claim 1, wherein the determining of the sequence of voltage step change information values according to the voltages relative to ground specifically comprises:
acquiring the information value of the sudden change amount of each phase voltage according to the voltage of each phase to ground; the ground-to-ground voltages comprise an effective value of ground-to-ground voltage before fault and an effective value of ground-to-ground voltage after fault;
and determining a voltage mutation amount information value sequence according to the voltage mutation amount information values of the phases.
4. The small-current grounding system fault phase selection method according to claim 3, wherein the obtaining of the information value of the sudden change amount of each phase voltage according to the voltage of each phase voltage specifically comprises:
determining a voltage break variable according to the effective value of the voltage after the fault and the effective value of the voltage before the fault;
and judging the size relationship between the voltage sudden-change quantity and a preset voltage sudden-change quantity, and determining the information value of the voltage sudden-change quantity according to the size relationship between the voltage sudden-change quantity and the preset voltage sudden-change quantity.
5. The small-current grounding system fault phase selection method according to claim 1, wherein before determining the grounding fault phase according to the voltage jump amount information value sequence, further comprising:
acquiring a voltage mutation information value sequence every preset time;
acquiring the continuous occurrence times of the same voltage mutation information value sequence;
and when the occurrence times of the same mutation quantity information value sequence are greater than the preset times, determining the phase of the ground fault according to the voltage mutation quantity information value sequence.
6. A low current grounding system fault phase selection device, comprising: the system comprises a data acquisition unit, a state acquisition unit, a mutation amount calculation unit and a fault phase judgment unit;
the data acquisition unit is used for acquiring zero sequence voltage and each phase-to-ground voltage of the small current grounding system;
the state acquisition unit is used for acquiring the state of the small current grounding system according to the zero sequence voltage; the states of the grounding system include: in a ground fault state and not in a ground fault state;
the abrupt change amount calculation unit is used for determining a voltage abrupt change amount information value sequence according to each phase-to-ground voltage when the state of the low-current grounding system is in a grounding fault state;
the fault phase judging unit is used for determining the phase of the ground fault according to the voltage mutation information value sequence;
when only one phase information value in the mutation quantity information value sequence is a first numerical value, the phase corresponding to the first numerical value is a ground fault phase;
when only one phase information value in the mutation quantity information value sequence is a second numerical value, acquiring a neutral point grounding mode information value; the neutral point grounding mode information value is determined according to the grounding mode of the system, and when the grounding mode of the system is a neutral point ungrounded mode or arc suppression coil under-compensation grounding mode, the neutral point grounding mode information value is a second numerical value; when the grounding mode of the system is arc suppression coil overcompensation grounding, the information value of the neutral point grounding mode is a first numerical value; the first numerical value is represented by 0 and the second numerical value is represented by 1;
when the neutral point grounding mode information value is a first numerical value, the left phase of the line corresponding to the second numerical value is a ground fault phase; when the neutral point grounding mode information value is a second numerical value, the right phase of the line corresponding to the second numerical value is a ground fault phase; wherein, the judged sequence is the circulating sequence of the A phase, the B phase and the C phase.
7. A terminal device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method according to any one of claims 1 to 5 when executing the computer program.
8. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 5.
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Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101291056A (en) * | 2007-04-17 | 2008-10-22 | 上海申瑞电力科技股份有限公司 | Faulty phase selection method based on long wire model |
| CN103558508A (en) * | 2013-10-31 | 2014-02-05 | 江苏镇安电力设备有限公司 | Insulation fault phase selection method based on IT system with neutral conductor |
| CN104267311A (en) * | 2014-09-12 | 2015-01-07 | 广东电网公司电力科学研究院 | Phase selection method for faults of double-circuit lines on same tower |
| CN104880647A (en) * | 2015-06-15 | 2015-09-02 | 中国矿业大学 | Earth fault phase identification method based on injection method |
| CN105375532A (en) * | 2015-12-14 | 2016-03-02 | 华中科技大学 | Fault phase selection method for double-fed wind power plant tie line |
| CN105699850A (en) * | 2016-03-29 | 2016-06-22 | 国网福建省电力有限公司 | Line grounding fault phase selection method realized by means of fault point current phase characteristic |
| CN106129978A (en) * | 2016-07-22 | 2016-11-16 | 中国电力科学研究院 | A kind of Zero sequence current differential protection phase-selecting method based on sequence difference stream and device |
| CN106990330A (en) * | 2017-05-27 | 2017-07-28 | 国家电网公司 | The discrimination method of one-phase earthing failure in electric distribution network phase |
| CN107026430A (en) * | 2016-01-29 | 2017-08-08 | 中国电力科学研究院 | A kind of double-circuit line on same pole phase-selecting method based on single-ended Sudden Changing Rate |
| CN107091970A (en) * | 2017-05-19 | 2017-08-25 | 国网天津市电力公司 | The Fault Phase Selection method of isolated neutral system |
| CN107632239A (en) * | 2017-08-25 | 2018-01-26 | 南京理工大学 | A kind of photovoltaic based on IMF Energy-Entropies sends out line fault phase-selecting method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017218558A1 (en) * | 2016-06-14 | 2017-12-21 | Schweitzer Engineering Laboratories, Inc. | Phase selection for traveling wave fault detection systems |
-
2018
- 2018-08-24 CN CN201810975678.XA patent/CN109085450B/en active Active
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101291056A (en) * | 2007-04-17 | 2008-10-22 | 上海申瑞电力科技股份有限公司 | Faulty phase selection method based on long wire model |
| CN103558508A (en) * | 2013-10-31 | 2014-02-05 | 江苏镇安电力设备有限公司 | Insulation fault phase selection method based on IT system with neutral conductor |
| CN104267311A (en) * | 2014-09-12 | 2015-01-07 | 广东电网公司电力科学研究院 | Phase selection method for faults of double-circuit lines on same tower |
| CN104880647A (en) * | 2015-06-15 | 2015-09-02 | 中国矿业大学 | Earth fault phase identification method based on injection method |
| CN105375532A (en) * | 2015-12-14 | 2016-03-02 | 华中科技大学 | Fault phase selection method for double-fed wind power plant tie line |
| CN107026430A (en) * | 2016-01-29 | 2017-08-08 | 中国电力科学研究院 | A kind of double-circuit line on same pole phase-selecting method based on single-ended Sudden Changing Rate |
| CN105699850A (en) * | 2016-03-29 | 2016-06-22 | 国网福建省电力有限公司 | Line grounding fault phase selection method realized by means of fault point current phase characteristic |
| CN106129978A (en) * | 2016-07-22 | 2016-11-16 | 中国电力科学研究院 | A kind of Zero sequence current differential protection phase-selecting method based on sequence difference stream and device |
| CN107091970A (en) * | 2017-05-19 | 2017-08-25 | 国网天津市电力公司 | The Fault Phase Selection method of isolated neutral system |
| CN106990330A (en) * | 2017-05-27 | 2017-07-28 | 国家电网公司 | The discrimination method of one-phase earthing failure in electric distribution network phase |
| CN107632239A (en) * | 2017-08-25 | 2018-01-26 | 南京理工大学 | A kind of photovoltaic based on IMF Energy-Entropies sends out line fault phase-selecting method |
Non-Patent Citations (2)
| Title |
|---|
| Fault location for power grid based on transient travelling wave data fusion via asynchronous voltage measurements;Liang Rui;《Electrical Power and Energy Systems》;20170623;第426-439页 * |
| 基于对地参数跟踪测量的不接地系统单相接地故障选相研究;赵军;《电力系统保护与控制》;20151101;第43卷(第21期);第81-85页 * |
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|---|---|
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