CN107728000B - Small-current grounding anti-error line selection method based on five-time phase-to-ground incremental current - Google Patents
Small-current grounding anti-error line selection method based on five-time phase-to-ground incremental current Download PDFInfo
- Publication number
- CN107728000B CN107728000B CN201710405146.8A CN201710405146A CN107728000B CN 107728000 B CN107728000 B CN 107728000B CN 201710405146 A CN201710405146 A CN 201710405146A CN 107728000 B CN107728000 B CN 107728000B
- Authority
- CN
- China
- Prior art keywords
- phase
- current
- fault
- grounding
- incremental
- 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.)
- Active
Links
- 238000010187 selection method Methods 0.000 title claims abstract description 7
- 238000012544 monitoring process Methods 0.000 claims abstract description 41
- 230000001052 transient effect Effects 0.000 claims abstract description 33
- 238000004364 calculation method Methods 0.000 claims abstract description 6
- 238000001514 detection method Methods 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims description 43
- 238000005070 sampling Methods 0.000 claims description 31
- 230000008859 change Effects 0.000 claims description 14
- 239000013598 vector Substances 0.000 claims description 7
- 238000004458 analytical method Methods 0.000 claims description 6
- 238000009825 accumulation Methods 0.000 claims description 4
- 230000010355 oscillation Effects 0.000 description 12
- 230000007704 transition Effects 0.000 description 11
- 230000005855 radiation Effects 0.000 description 10
- 230000001629 suppression Effects 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 6
- 230000000737 periodic effect Effects 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 238000004088 simulation Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 230000002265 prevention Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000009413 insulation Methods 0.000 description 3
- 239000004020 conductor Substances 0.000 description 2
- 238000005034 decoration Methods 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000035772 mutation Effects 0.000 description 2
- 238000004422 calculation algorithm Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000012850 discrimination method Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
- 238000003878 thermal aging Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Emergency Protection Circuit Devices (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
The invention relates to a small-current grounding error-preventing line selection method based on five-time phase-to-ground incremental current1SIf not, qualitatively judging whether suspected grounding or electric leakage occurs or not; secondly, the incremental current of a certain phase of secondary transient phase is greater than the corresponding set value and greater than other two phases K through calculation and comparison1SIf not, determining whether to accumulate the suspected failure times; thirdly, after calculation and comparison, the transient phase earth increment current value is respectively greater than the other two phases K2SIf not, whether the grounding phase of the grounding line is in the first judgment or not is judged, or whether the leakage phase of the intermittent leakage line is in the second judgment or not is judged according to the times of the secondary transient faults within 3 seconds; fourthly, calculating half-cycle phase earth incremental current phase differences of two non-fault phases in the 8 th cycle after the fault or three-phase current, and using the half-cycle phase earth incremental current phase differences or the three-phase current as double anti-error judgment; the grounding phase grounding incremental current value after 5 seconds of detection comparison fault is greater than the non-grounding phase grounding incremental current value KHSAnd if not, monitoring whether the fault is continuous or not.
Description
Technical Field
The invention relates to a small-current grounding line selection preventing method for a power distribution network, in particular to a small-current grounding line selection preventing method based on five-time phase-to-ground incremental current.
Background
In the existing distribution network low-current single-phase grounding typical monitoring technical method, the following problems exist:
1. the traditional monitoring technology compares the steady-state zero-sequence current value and the power direction of different branch circuits of the same power bus after the ground fault, and judges the circuit with the maximum zero-sequence current amplitude and the zero-sequence power direction from the circuit to the bus as the fault circuit. The technology can be used in principle in the conventional distribution network line without arc suppression coils, but after the arc suppression coils are arranged in the distribution network, the amplitude of the post-steady-state zero-sequence current of different branch lines of the same power bus is similar and the zero-sequence power direction is the same after the ground fault, and the traditional monitoring technology is difficult to distinguish the fault line from the non-fault line.
2. The zero sequence current mutation quantity comparison method solves the problem of line selection of single-phase grounding between multiple radiation lines of the same bus in a distribution network provided with arc suppression coils, but has the problem of misjudgment and misinformation of non-grounding lines when adjacent lines of a closed loop network are grounded or the operational disturbance oscillation zero sequence current shown in figure 3(a) and the induced disturbance oscillation zero sequence current shown in figure 4(a) appear.
3. A distribution network single-phase earth fault section positioning method based on phase current break variables is characterized in that a three-phase current break variable similarity coefficient comparison method and a fault line monitoring point identification method are used for judging a fault section by considering that no voltage signal source exists in a radiation line. The method can be theoretically suitable for multi-branch radiation lines under the same bus, but the method of mathematically deriving the phase current abrupt change is only adopted to distinguish the load change from the single-phase grounding, so that the difference between the transformer excitation inrush current and the single-phase grounding current containing the non-periodic component is difficult to distinguish; the method for setting and calculating the harmonic proportion and the similar coefficient of the three-phase current abrupt change quantity according to different situations on site is not suitable for voltage zero-approaching phase single-phase grounding and is complex to apply; on the other hand, when the operational disturbance oscillation phase current sudden change amount shown in fig. 3(b) and the induced disturbance oscillation phase current sudden change amount shown in fig. 4(b) appear, there is a problem of false judgment of the non-grounded line as well.
4. The intelligent grounding power distribution system combining the power neutral point low resistance with the bus three-phase metallic grounding soft switch can effectively inhibit resonance overvoltage possibly caused by continuous low-resistance single-phase grounding, but the system adopts the traditional stage type zero-sequence current protection to carry out grounding line selection, so that the system is not suitable for high-medium-resistance single-phase grounding, and the scheme needs to transform triangular connection wires of a plurality of distribution network power transformers into star connection wires, so that the implementation cost of the scheme is high.
5. Other low-frequency signal injection method low-current single-phase grounding detection technologies have a good detection effect on low-resistance grounding, but are not suitable for high-medium-resistance single-phase grounding, and medium-voltage signal injection equipment needs to be added, so that on one hand, low-frequency current impact to a certain degree on a distribution network line exists, and on the other hand, the problems of safety management risks of newly-added medium-voltage equipment and engineering implementation are brought to a distribution network site.
6. The grounding detection technology using wavelet analysis is easy to misjudge and report in load fluctuation; the traveling wave fault positioning technology has a good theoretical effect on detecting single-phase grounding of a single line, but is not suitable for a power distribution network with a complex structure.
Comprehensively induces the problems of the prior similar technical method for grounding monitoring, wherein the most important method is that the misjudgment and the false alarm probability are high; according to research and analysis, the fundamental reason is that the time-state signals of the grounding characteristics used by all the discrimination methods are single, and the authenticity of the single-phase grounding is difficult to distinguish.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the prior art, the small-current grounding automatic line selection method suitable for the modern power distribution network including the closed-loop circuit is provided, the grounding automatic line selection problem is effectively solved, meanwhile, the false-proof judgment of true and false small-current grounding is considered, and the accuracy and reliability requirements on the small-current grounding line selection are met.
The technical scheme is as follows: a small-current grounding error-preventing line selection method based on five-time phase-to-ground incremental current comprises the following steps:
connecting secondary outgoing lines of current transformers of all monitoring points with current sampling loops of corresponding grounding monitors; secondly, k for calculating and comparing whether the sudden change of the zero-sequence current is greater than a set value or not or whether the sudden change of the grounding phase current is greater than the non-grounding phase current1SDouble judgment, qualitative judgment of doubtfulWhether grounding or electric leakage occurs; measuring and comparing the incremental current of a certain phase of secondary transient phase to be larger than a corresponding set value and the incremental current of other two phases K1SIf not, determining whether to accumulate the suspected failure times; fourth, after the calculation and comparison, the transient phase-to-phase incremental current values are respectively larger than the other two phases of the phase-to-ground incremental current values K2SIf not, whether the grounding phase of the grounding line is in the first judgment or not is judged, or whether the leakage phase of the intermittent leakage line is in the second judgment or not is judged according to the times of the secondary transient faults within 3 seconds; calculating half cycle phase incremental current phase difference or three-phase incremental current of two non-fault phases in the 8 th cycle after the fault is used as double anti-error judgment; sixthly, detecting that the ground phase ground incremental current value after 5 seconds of comparison fault is larger than the non-ground phase ground incremental current value KHSAnd if not, monitoring whether the fault is continuous or not.
Further, the method comprises the following steps:
(2.1) calculating the accumulated value of the three-phase full-cycle current sampling absolute value of the 2 nd cycle before the current time in real time:
when the value is larger than zero, directly measuring and calculating the zero-sequence current break variable and the three-phase current break variable: i.e. i0k-i0k-2N＝Δi0k、iAk-iAk-2N＝ΔiAk、iBk-iBk-2N＝ΔiBk、iCk-iCk-2N＝ΔiCk(ii) a When the value is not more than zero, firstly adopting a vector analysis method to calculate a symmetrical component iASk、iBSk、iCSkAnd then calculating the three-phase current break variable and the zero-sequence current break variable: i.e. iAk-iASk＝ΔiAk、iBk-iBSk＝ΔiBk、iCk-iCSk＝ΔiCk、ΔiAk+ΔiBk+ΔiCk＝Δi0k(ii) a (2.2) firstly, the zero sequence current break variable and the set value i of the zero sequence current break variable are calculated0SIn comparison, when | Δ i occurs0k|>i0SIf so, qualitatively judging that the fault occurs, recording the time k equal to 0 and t equal to 0, starting the accumulation of sampling times and time, and storing all the sampling data after k equal to-2N to k equal to 1; then, turning to the step three; when | Δi0k|<Δi0SThen, the three-phase current break variables delta i are respectively convertedAk、ΔiBk、ΔiCkWith a set value i of the quantity1SComparing, when the value of one phase is larger than the set value and the phase current sudden change amount is larger than the k of the other two phases1SWhen the sampling time is doubled, the fault is judged to be generated qualitatively, the time k is recorded as 0, t is recorded as 0, the accumulation of the sampling times and time is started, and all the subsequent sampling data from k to k as 1 and 2N are stored; then, turning to the step three;
wherein N is the sampling frequency of each power frequency period, k is the sampling sequence number from the beginning of the fault, t is the timing from the beginning of the fault, iAk、iBk、iCkRespectively, the kth A, B, C-th phase current sample value, IAQ、IBQ、ICQRespectively, the accumulated values i of the full-cycle current sampling absolute values of the A, B, C phases in the 2 nd cycle before the current time0kFor the kth zero-sequence current sample value, i0k-2NFor sampling zero-sequence current values of two power frequency periods before the kth sequence number, iAk-2N、iBk-2N、iCk-2NRespectively A, B, C phase current sampling values of two power frequency periods before the kth serial number.
Further, the step three comprises the following steps:
(3.1) calculating the accumulated value of the absolute value of the phase-to-ground incremental current in the three-phase sub-transient period
(3.2) if IAG1Or IBG1Or ICG1Greater than a set value I1SComparing the accumulated values of the three phases, and when the value of one phase is larger than the value K of the other two phases1SWhen multiplying, it corresponds to L A1 or L B1 or L C1, starting from T0, accumulating successively; if not, the accumulated value is larger than the set value I1setOr the value of one phase is not greater than the value K of the other two phases1SIf the conditions are doubled, the program returns;
wherein L isA、LB、LCA, B, C phase leakage flag bits respectively, and T is the accumulated times of leakage.
Further, the step fourth includes the steps of:
(4.1) measuring and calculating the sampled phase-to-ground incremental current of the transient three-phase current by using a fault component algorithm; (4.2) calculating the accumulated value of the incremental absolute value
(4.3) comparing the accumulated values of the three phases, and when the value of one phase is greater than the K of the other two phases2SSetting the fault flag position of the item when the fault is doubled, and initially selecting the phase as a fault line fault phase; k when the value of one phase is not greater than that of the other two phases2SIf the time T is equal to 3 seconds and T is more than or equal to 3, the time T is determined to correspond to L A1 or L B1 or LCIf the phase 1 is a faulty line phase in which intermittent leakage occurs and the conditions that T is 3 seconds and T is not less than 3 are not met, the routine returns.
Further, the step fifthly comprises the following steps:
(5.1) when the fault is judged to be the earth fault, calculating and enabling the half cycle phase earth incremental current of the non-fault phase of the 8 th power frequency cycle after the fault to be corresponding to a set value I8SComparing; (5.2) when the increment is larger than the set value, calculating the initial phase of the phase-to-ground incremental current of the two non-fault phases and the phase difference delta theta of the two non-fault phases8The program leads in a phase difference comparison section; otherwise, the incremental three-phase comparison section is led in; (5.3) when the program is introduced into the phase difference comparison section, the delta theta is calculated8With a set angle value theta8SIn comparison, when | Δ θ |8| is less than θ8SIf so, the selected phase is determined to be a fault phase of the fault line; when | Δ θ8| is not less than θ8SIf yes, confirming the fault as non-grounding or non-leakage fault, and returning the program; (5.4) when the program is introduced into the incremental three-phase comparison section, respectively calculating incremental currents of a fault phase in the 8 th week after the fault and a half-cycle phase of a non-fault phase, and comparing the incremental currents with the incremental currents; when the current is greater than the current K in the non-fault phase8SWhen the fault is detected, the fault is determined as grounding or leakage fault; whether or notThe routine returns.
Further, the step sixteenth includes the following steps:
and (3) carrying out subsequent fault state monitoring by each grounding monitor sending a fault report: (6.1) calculating the three-phase current sampling accumulated value after 5 seconds of fault
Wherein the subscript j is the sampling times which are accumulated after 5 seconds of failure; (6.2) calculating the phase-to-ground incremental current value I5 seconds after the faultAH-IAQ＝IAGH、IBH-IBQ＝IBGH、ICH-ICQ＝ICGH(ii) a (6.3) comparing the delta current values of the three phases, when the fault phase is detected, the value is respectively greater than K of the values of the other two phasesHSWhen the current is doubled, the grounding or leakage fault is reported to be continuous; otherwise, the phase-to-phase earth incremental current value of the earth phase is not larger than the value K of the other two phases after 3 seconds of continuous detectionHSIn the case of double condition, the loss of the grounding or leakage fault is reported.
Further, the calculated value of the phase-to-ground incremental current is an accumulated value of absolute values of sampling increments, and includes calculating the accumulated value as a half-cycle average value, a full-cycle average value, an amplitude value or an effective value.
Has the advantages that: compared with the existing low-current grounding monitoring method, the method has the following basic effects:
firstly, the phase-to-phase incremental current of a secondary transient state and a post-transient state with relatively large signal intensity is used as a basic criterion signal source, so that the method is suitable for high-resistance, medium-resistance and low-resistance single-phase grounding of distribution networks with various structures including loop closing circuits under all voltage phases of different intervals of the same medium-voltage electrical connection;
secondly, the used criterion information is comprehensive and rich, and the applicable single-phase grounding resistance range is correspondingly improved because the grounding phase sub-transient phase incremental current of the grounding line is generally larger than the zero-sequence incremental current;
thirdly, the invention is not only suitable for single-phase grounding of continuous and discontinuous power frequency waves, but also suitable for single-phase grounding of periodic or aperiodic non-full-period power frequency waves shown in figure 5, so that electric leakage and grounding caused by insulation damage caused by environment, weather, thermal aging and other reasons can be found early. In fig. 5, the sickle wave is a non-full-frequency power frequency wave, which exhibits a non-periodic sickle-shaped intermittent wave at the initial stage of the insulation damage, and then gradually develops into a periodic sickle-shaped intermittent wave, and the periodic sickle wave is alternated with a full-frequency power frequency wave, and then continuously develops into a full-periodic full-frequency continuous wave.
The invention has multiple false-proof discrimination functions for real and suspected low-current grounding, so that the reliability and accuracy of low-current grounding line selection are substantially improved.
Drawings
FIG. 1 is a block diagram of an implementation procedure of the present invention, in which: Δ i0、Δi0SThe zero sequence current mutation quantity and the over-limit value thereof; Δ iA1、ΔiB1、ΔiC1And i1SRespectively phase ground current sudden change and an over-limit set value thereof; i isAG1、IBG1、ICG1、I1SRespectively a sub-transient three-phase earth incremental current and an over-limit set value thereof; i isAG2、IBG2、ICG2Respectively, post-transient three-phase-to-ground incremental current values; i isAG8、IBG8、ICG8、I8SRespectively the non-fault phase half-cycle phase incremental current and the over-limit set value of the non-fault phase half-cycle phase incremental current in the 8 th power frequency cycle after the fault; delta theta8、θ8SPhase difference of half cycle phase earth incremental current corresponding to two non-grounding phases and corresponding set values thereof respectively; k is a radical of1S、K1S、K2S、K8S、KHSAnd the phase-to-ground incremental current multiplying power set values of the fault phase relative to the non-fault phase in a transient state, a sub-transient state, a post-transient state, a transition state and a post-steady state are respectively set.
Fig. 2 is a simplified distribution network model and a distribution diagram of amplitude and polarity of a sub-transient three-phase-to-ground incremental current and a zero-sequence incremental current, which are grounded when a G point of a closed loop circuit is at a phase of a phase C voltage; in fig. 2, the 10kV side of the power transformer is a triangular connection wire widely used in the actual distribution network, and P00 is the number of the side switch and the monitoring point thereof; r11 and R21 are respectively the looped network outgoing switch and the monitoring point number thereof; r12 and R13, R14 and R15 are respectively the in-out switch of the ring main unit and the monitoring point number thereof; b31 and B32 are respectively an outgoing line switch and a branch switch of the radiation circuit and the monitoring point numbers thereof; the EPLG is the sum of the earth capacitances of all equivalent parallel circuits except the loop circuit and the radiation circuit marked in the figure; XHQ is arc suppression coil connected below the Z connection grounding transformer, and the overcompensation degree of the arc suppression coil is 10%.
Fig. 3(a) and fig. 3(B) are respectively simulation waveforms of zero-sequence incremental current and three-phase-to-ground incremental current monitored at a point B31 by operational disturbance oscillation caused by non-simultaneous closing of three phases when the simplified distribution network model in fig. 2 transmits power to an open-loop line.
Fig. 4(a) and fig. 4(b) are respectively simulation waveforms of zero sequence incremental current and three-phase-to-ground incremental current monitored at point P00 by induced disturbance oscillation of the simplified distribution network model of fig. 2 due to lightning arrester leakage lightning charge occurring on a radiation line.
Fig. 5 is a simulation waveform of phase-to-ground incremental current of a single-phase ground and phase-to-ground incremental current of a ground phase in an initial stage of insulation damage of large, medium and small power distribution networks with phase-to-ground capacitance within 150 muF of the simplified 10kV distribution network model in fig. 2.
Fig. 6 is a five-time three-phase incremental current simulation waveform diagram of a simplified 10kV distribution network model, in which 10k Ω transition resistance single-phase grounding occurs at monitoring points of power supply and bus outgoing line switches P00, R11, R12, R21 and R31 when a G point of a closed loop circuit C phase is in a voltage amplitude phase.
Fig. 7 is a three-phase incremental current simulation waveform diagram of points R11 and R12 of the simplified 10kV distribution network model of fig. 2, where 10k Ω transition resistance single-phase grounding occurs when the point G of the closed loop line C phase is in the voltage zero phase.
FIG. 8 shows the R with the most severe frequency-division oscillation when the loop-closing circuit is connected to the A-phase G point with 10k omega transition resistance and low current grounding12Three-phase delta current waveform plot for the monitoring point within 3 seconds.
Detailed Description
The invention is further explained below with reference to the drawings.
1. The small current grounding monitoring system is constructed as follows:
as shown in fig. 2, the grounding monitor of the invention is installed at monitoring points of each power switch, outlet switch, ring network circuit switch, radiation circuit switch, etc. in the distribution network, and the three-phase current transformer and zero-sequence current transformer of each circuit switch are respectively connected with the grounding monitor at the monitoring points; the grounding monitor of each monitoring point is connected with the communicator shared at the monitoring point, each communicator is connected with the central communicator, and the central communicator is connected with the central monitor, so that the low-current grounding monitoring system of the distribution network shown in fig. 2 is formed.
2. Setting five time-state related fixed values related to fault line selection of the grounding monitor:
according to the fixed value setting principle of covering high, medium and low resistance low current grounding or leakage faults and considering the minimum shunt ratio of the closed loop circuit, five time-state related fixed values of the low current grounding or leakage fault line selection in the distribution network model of FIG. 2 are set as: i.e. i0S＝0.1A、i1S＝0.15A、k1S＝1.5、I1S＝5A、K1S＝1.5、K2S＝1.3、I8S＝4A、θ8S＝60°、K8S＝1.2、KHS＝1.2。
3. The working process of the invention when the 10k omega transition resistance grounding occurs at the C-phase G point of the closed loop circuit shown in figure 2 is as follows:
when the point G is grounded by a C-phase 10k omega transition resistor, the magnitude relation and direction of three-phase sub-transient phase-to-ground incremental current and zero-sequence incremental current at each monitoring point on the network are shown by arrows at each corresponding monitoring point in figure 2; phase-to-ground incremental current simulation waveforms of the power supply monitoring point, the P00, R11, R12 and R21 monitoring points of the loop closing circuit and the radiation circuit outgoing line B31 monitoring point in five time states are shown in figure 6. The working process of the monitor of each monitoring point is as follows:
after the phase-to-ground incremental current of the non-grounded phase of the full distribution network collected by the G point flows into the C-phase circuit from the grounding resistor, the phase-to-ground incremental current respectively flows to the bus from two directions: one path flows to the bus and the power supply through the monitoring points R11, the other path flows to the bus and the power supply through the monitoring points R12, R13, R14, R15, R21 and the like, and the secondary transient phase ground currents of the two loops are in the looped network and are in opposite flow directions by taking the contact point of the ground resistance and the C-phase lead of the looped network.
The path from the monitoring point of R11 to the bus is short, the line impedance is small, and the incremental current of the fault phase earth flowing to the reference power supply side is relatively large, so that the transient qualitative judgment: the current cycle 2 current monitored by the point monitor in the grounding phase is larger than 0, and the absolute value | delta i of the transient zero sequence current break variable0|>i0SA set value of 0.1A or absolute value | Δ i of ground phase transient phase ground increment currentC1|>i1S0.15A, and satisfies | Δ iC1|>k1S|ΔiA1|＝1.5|ΔiA1|、|ΔiC1|>k1S|ΔiB1|＝1.5|ΔiB1If the characteristics meet the criterion of transient earth fault, the earth fault or earth leakage fault is judged qualitatively, and the sum t of the sampling times of the faults starting from k to 0 and k to k +1 is k/fcThe program is imported to carry out quantitative judgment when the fault is timed; second transient state quantitative error-proof judgment: the sum of the half-cycle absolute values of the incremental current of the fault phase sub-transient phase detected by the monitor is ICG114.25A, greater than I1SThe corresponding set value of 5A; the sum of the values of the non-grounded phases is IAG1＝IBG11.527A, in accordance with ICG1(＝14.25A)>K1SIAG2(＝1.5×1.527＝2.29A)、ICG1(＝14.25A)>K1SIBG2(1.5 × 1.527 ═ 2.29A) sub-transient ground fault criterion condition; thirdly, post-transient quantitative false-proof judgment: the three-phase earth current values of the post-transient state are increased under the condition that the arc suppression coil resonant circuit is gradually acted, wherein the sum of absolute values of half cycles of phase earth incremental current of the fault phase is ICG2The sum of the values for the non-faulted phases is I9.39AAG22.17A, corresponds to ICG2(＝9.39A)>K2SIAG2(＝1.3×2.17＝3.255A)、ICG2(＝9.39A)>K2SIBG2The post-transient grounding criterion condition (1.3 multiplied by 2.17) 3.255A eliminates the possibility of induced disturbance oscillation with similar characteristics of post-transient three-phase ground incremental current values; accordingly, the R110 point monitor initially judges that the C phase of the loop line is the grounding phase of the grounding line(ii) a Fourthly, transition state double error prevention judgment: r11 takes the first half cycle phase earth incremental current of 8 th power frequency cycle after the fault to carry out double anti-error judgment: calculating the sum of absolute values of half-cycle phase earth incremental currents of the A phase of the ungrounded phase to be IAG89.537A, the sum of which is greater than the corresponding setpoint I8S4A, the accuracy of the incremental current phase calculation of the non-grounding phase is not influenced; then, the phase-to-ground incremental current phase difference theta of the two non-grounded phases is calculatedAG8-θBG8＝Δθ8The phase difference is calculated to be about 0 DEG in accordance with | Delta theta8|<θ8SAnd (3) the grounding phase difference criterion condition of the non-fault phase of the fault line at the end of the transition state (60 degrees) eliminates the possibility of non-simultaneous switching-on disturbance oscillation of the three-phase earth incremental current phase difference of 120 degrees, and then confirms that the C phase of the line is the fault phase of the fault line.
The line sections monitored by the points such as R12, R13, R14, R15 and R21 have long series paths, and although the impedance of the phase-to-ground incremental current loop is relatively large and the C-phase-to-ground incremental current flowing to the power supply is relatively weak, all the false line selection prevention determination processes of R11 can be repeated at these monitoring points, and the C-phase of the line is confirmed to be the ground line grounding phase.
The power supply P00 monitoring point also repeats all the false line selection prevention determination process of R11, and confirms that the line C phase below it is the ground phase.
When the monitoring point of the radiation circuit B31 is grounded at the point G, a sub-transient zero sequence or phase ground current sudden change which can be over-limited exists, qualitative judgment of the grounding monitor at the point is possibly started, but quantitative judgment is not passed because the current value of transient three-phase ground incremental current is the same.
After 5 seconds of earth fault, each earth monitor sending the fault report detects that the absolute value accumulated value of the phase earth incremental current of the earthed phase in the whole period is 71.26A, the absolute value accumulated value of the phase earth incremental current of the non-earthed phase in the whole period is 40.72A, and the phase earth incremental current conforms to ICGH(71.26A)>KHSIAGH(＝1.2×40.72＝48.86A)、ICGH(71.26A)>KHSIBGHThe grounded state is confirmed to be continued by the criterion condition of the grounded continuation characteristic (1.2 × 40.72 — 48.86 a).
And respectively reporting the fault information of the point and the incremental current values of the secondary transient phases of the grounding phases to a monitoring center by grounding monitors of the points P00, R11, R12, R13, R14, R15 and R21 of the fault phases of the fault lines detected.
4. Monitoring center manually judges fault section
After the monitoring center receives grounding fault information and grounding phase secondary transient phase incremental current value reports of P00, R11, R12, R13, R14, R15 and R21 points, a worker on duty is operated by the center to judge a fault section, and the judging method comprises the following steps:
first, since the power supply monitoring points and the loop closing circuit transmit the ground or leakage report, the loop closing circuit is judged as a faulty circuit, and then a faulty section is further judged between the monitoring points of the loop closing circuit transmitting the report.
And secondly, comprehensively comparing the incremental current difference of the fault secondary transient phase between each two adjacent monitoring points, and judging the difference between the R11 and the R12 as a fault interval because the difference between the R11 and the R12 is the largest. (see FIG. 6)
If single-phase grounding or leakage faults occur at other positions of the distribution network, such as a bus and a radiation line, the working process description is not repeated because the number of the grounding monitors for quantitative judgment of starting is less than the starting number of the faults occurring in the loop closing line.
The invention can be widely applied to the low-current single-phase grounding or leakage-proof line selection of the power distribution network of modern power distribution networks including multi-power-supply loop-closing circuits and the power distribution networks of enterprises and institutions in other industries.
In the forming process, the method of the invention respectively simulates and simulates the small current grounding of distribution networks with various structures including the model shown in figure 2 in different position intervals of different lines, different voltage phases and different resistance values, and sums up the relational characteristics of three-phase ground incremental current and zero-sequence incremental current of a fault line and a non-fault line when small current grounding occurs in the distribution network configured with parallel arc suppression coils and the relational characteristics of three-phase ground incremental current and zero-sequence incremental current of suspected small current grounding disturbance oscillation on the basis of recorded small current grounding phase incremental current and zero-sequence current waveforms and recorded phase and zero-sequence oscillation of suspected small current grounding transition resistance, and collects the relational characteristics in table 1; these current relationship characteristics become the basis for the regularity of the method of the present invention.
In the subscripts of each of the time-state current vectors listed in table 1: FG represents a fault phase of a fault line and a suspected fault phase of the suspected fault line, SG represents a non-fault phase of the fault line, F0 represents a zero-sequence component of the fault line, S0 represents a zero-sequence component of the non-fault line, AG, BG and CG respectively represent three phase-to-ground components of the non-fault line, and H represents a post-steady state; the transient state break variable subscript 1 represents the first break variable after the ground fault, and the other time state current vector subscripts 1, 2 and 8 represent the half-cycle vectors of the 1 st, 2 nd and 8 th cycles after the fault respectively; k is a radical of1、K1、K2、K8、KHThe incremental current multiplying power of the fault phase and the non-fault phase of the fault line in the transient state, the sub-transient state, the post-transient state, the transition state and the post-steady state respectively; the measuring ranges are respectively k1≥2～3；K1≥2～3；K2≥1.6～2；K8≥1.4～2；KH＝1.4～2。
TABLE 1 Small-current grounding and disturbance oscillation five-time phase grounding incremental current relation characteristic comparison table
The related definitions and conceptual descriptions related to the method of the invention are as follows:
1. definition of phase-to-ground delta current
In a low-current grounding system, the amount of current respectively increased in a three-phase line due to the occurrence of single-phase grounding or pseudo single-phase grounding; the incremental current is called a phase-ground incremental current because it loops around the three-phase conductor and the impedance between the three-phase conductor and the ground.
2. Definition of five-hour phase-to-ground delta current
Transient phase-to-ground incremental current-the relative-to-ground characteristics are reflected in the first current sample after single-phase grounding or suspected single-phase groundingThe incremental current of the relation comprises a zero-sequence current break variable and a phase current break variable with a symbol of delta i01、ΔiA1、ΔiB1、ΔiC1。
Sub-transient phase-to-ground incremental current-phase-to-ground incremental current in the latter half of power frequency cycle after single-phase grounding or suspected single-phase grounding occurs; symbol is
The calculated magnitude of which in the present method is denoted as IAG1、IBG1、ICG1。
Transient phase-to-ground incremental current-phase-to-ground incremental current in the 1 st power frequency cycle after single-phase grounding or suspected single-phase grounding occurs; symbol is
Which is used in the method as a temporal reference (not actually used in the method procedure) for defining the delta current for the sub-transient and post-transient phases.
Post-transient phase-to-ground incremental current-phase-to-ground incremental current in the 2 nd power frequency cycle after single-phase grounding or suspected single-phase grounding occurs; symbol is
The calculated magnitude of which in the present method is denoted as IAG2、IBG2、ICG2。
Post-steady-state phase-to-ground incremental current-power frequency phase-to-ground incremental current which enters a steady state after single-phase grounding or suspected single-phase grounding occurs; symbol is
The calculated magnitude of which in the present method is denoted as IAGH、IBGH、ICGH。
Transient phase-to-ground incremental current-power frequency phase-to-ground incremental current from the end of the secondary transient to the beginning of the post-steady state.
In the method, the 2 nd power frequency period after the fault used as primary line selection and error identification prevention is used as double error identification preventionThe phase-to-ground incremental current of the 8 th power frequency cycle after the fault belongs to transition state current when the medium and high resistances are grounded, and belongs to post-steady state current when the low resistances are grounded; wherein the current sign is in the first half of cycle 8
The calculated magnitude of which in the present method is denoted as IAG8、IBG8、ICG8。
The five-time phase earth incremental current is defined by a current waveform sample after single-phase grounding based on a continuous power frequency sine wave, and the single-phase grounding of the periodic non-full-period phase earth current power frequency wave has only one phase earth current waveform with relatively consistent amplitude and shape in the five-time state, but does not influence the method to effectively judge the current waveform.
3. Acquisition mode of five-time phase-to-ground incremental current
All three-phase or two-phase currents before and after the required fault can be directly detected, and the phase-ground incremental current obtained by direct subtraction through a fault component method is called holographic phase-ground incremental current, which is referred to as phase-ground incremental current in the invention for short; when the current after the fault and before the fault is lacked can be directly detected, the phase-to-ground incremental current can be obtained only by adopting the current vector after the fault through analysis operation, so that the phase-to-ground incremental current is called as the analysis phase-to-ground incremental current; the latter are mentioned in the present invention but are not within the scope of the patent claims.
4. When the zero sequence current of the non-fault line and the fault line is grounded, namely the small current single phase, the increment current value and the direction of each time phase of the fault phase and the non-fault phase of the non-fault line are basically the same, so that the symbol of the transient zero sequence current is 3I ″0(ii) a The fault phase of the fault line merges the non-grounding phase-to-phase incremental current of the whole network from the grounding resistor in the secondary transient state, and the merged current is opposite to the phase-to-ground incremental current of the non-grounding phase of the fault line, so that the secondary transient zero-sequence current of the fault line belongs to the sum of the vectors of the three-phase unequal-value incremental currents of the grounding phase and the non-grounding phase, and the symbol is expressed as
5. High resistance, medium resistance, low resistance and metallic grounding are defined in the design accuracy monitoring range according to the proportional relation of the grounding resistance value and the line voltage, wherein 1 omega/V-0.1 omega/V is defined as high-resistance grounding, 0.1 omega/V-0.01 omega/V is defined as medium-resistance grounding, 0.01-0.001 omega/V is defined as low-resistance grounding, and less than 0.001 omega/V is defined as metallic grounding.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (7)
1. A small current grounding error-preventing line selection method based on five-time phase-to-ground incremental current is characterized by comprising the following steps:
connecting secondary outgoing lines of current transformers of all monitoring points with current sampling loops of corresponding grounding monitors; secondly, k for calculating and comparing whether the sudden change of the zero-sequence current is greater than a set value or not or whether the sudden change of the grounding phase current is greater than the non-grounding phase current1SIf not, qualitatively judging whether suspected grounding or electric leakage occurs or not; thirdly, measuring and calculating K for comparing the incremental current of a certain phase of secondary transient phase with the corresponding set value and the incremental current of other two phases of secondary transient phase1SIf not, determining whether to accumulate the suspected failure times; fourthly, calculating and comparing that the transient phase-to-ground incremental current values after the phase are respectively larger than the values K of the other two phases2SIf not, initially judging whether the phase is a grounding phase of the grounding line or not, or judging whether the phase is an intermittent leakage line leakage phase according to the times of the secondary transient fault within 3 seconds; calculating a half-cycle phase earth incremental current phase difference or three-phase half-cycle phase earth incremental current of two non-fault phases in the 8 th cycle after the fault, and using the phase difference or the three-phase half-cycle phase earth incremental current as double anti-error judgment; sixthly, detecting that the ground phase ground incremental current value after 5 seconds of comparison fault is larger than the non-ground phase ground incremental current value KHSAnd if not, monitoring whether the fault is continuous or not.
2. The small-current grounding fault-line-selection-preventing method based on the five-time phase-ground incremental current is characterized by comprising the following steps of:
(2.1) calculating the accumulated value of the three-phase full-cycle current sampling absolute value of the 2 nd cycle before the current time in real time:
when the accumulated value is larger than zero, directly measuring and calculating the zero-sequence current break variable and the three-phase current break variable: i.e. i0k-i0k-2N＝Δi0k、iAk-iAk-2N＝ΔiAk、iBk-iBk-2N＝ΔiBk、iCk-iCk-2N＝ΔiCk(ii) a When the accumulated value is not more than zero, firstly adopting a vector analysis method to calculate a symmetric component iASk、iBSk、iCSkAnd then calculating the three-phase current break variable and the zero-sequence current break variable: i.e. iAk-iASk＝ΔiAk、iBk-iBSk＝ΔiBk、iCk-iCSk＝ΔiCk、ΔiAk+ΔiBk+ΔiCk＝Δi0k(ii) a (2.2) firstly, the zero sequence current break variable and the set value i of the zero sequence current break variable are calculated0SIn comparison, when | Δ i occurs0k|>i0SIf so, qualitatively judging that the fault occurs, recording the time k equal to 0 and t equal to 0, starting the accumulation of sampling times and time, and storing all the sampling data after k equal to-2N to k equal to 1; then, turning to the step three; when | Δ i0k|<Δi0SThen, the three-phase current break variables delta i are respectively convertedAk、ΔiBk、ΔiCkWith a set value i of the quantity1SComparing, when a phase current sudden change amount is larger than the set value and the phase current sudden change amount is larger than k of the other two phases1SWhen the sampling time is doubled, the fault is judged to be generated qualitatively, the time k is recorded as 0, t is recorded as 0, the accumulation of the sampling times and time is started, and all the subsequent sampling data from k to k as 1 and 2N are stored; then, turning to the step three;
wherein N is the sampling frequency of each power frequency period, k is the sampling sequence number from the beginning of the fault, and t is the timing from the beginning of the fault，iAk、iBk、iCkRespectively, the kth A, B, C-th phase current sample value, IAQ、IBQ、ICQRespectively, the accumulated values i of the full-cycle current sampling absolute values of the A, B, C phases in the 2 nd cycle before the current time0kFor the kth zero-sequence current sample value, i0k-2NFor sampling zero-sequence current values of two power frequency periods before the kth sequence number, iAk-2N、iBk-2N、iCk-2NRespectively A, B, C phase current sampling values of two power frequency periods before the kth serial number.
3. The small-current grounding error-prevention line selection method based on the five-time phase-to-ground incremental current according to claim 2, wherein the step three comprises the following steps:
(3.1) calculating the accumulated value of the absolute value of the phase-to-ground incremental current in the three-phase sub-transient period
(3.2) if IAG1Or IBG1Or ICG1Greater than a set value I1SComparing the accumulated values of the three phases, and when the accumulated value of one phase is larger than the accumulated values K of the other two phases1SWhen multiplying, it corresponds to LA1 or LB1 or LC1, starting from T0, accumulating successively; if not, the accumulated value is larger than the set value I1SOr the accumulated value of one phase is not more than the accumulated values K of the other two phases1SIf the conditions are doubled, the program returns;
wherein L isA、LB、LCA, B, C phase leakage flag bits respectively, and T is the accumulated times of leakage.
4. The small-current grounding fault-line-selection-prevention method based on the five-tense phase-to-ground incremental current is characterized in that the step four comprises the following steps:
(4.1) fault componentCalculating the sampled phase-to-ground incremental current of the transient three-phase current after the calculation; (4.2) calculating the accumulated value of the incremental absolute value
(4.3) comparing the accumulated values of the three phases, and when the accumulated value of one phase is greater than K of the accumulated values of the other two phases2SSetting the fault flag position of the phase when the phase is doubled, and primarily selecting the phase as a fault line fault phase; when the accumulated value of one phase is not greater than K of the accumulated values of the other two phases2SIf the time T is equal to 3 seconds and T is more than or equal to 3, the time T is determined to correspond to LA1 or LB1 or LCIf the phase 1 is a faulty line phase in which intermittent leakage occurs and the conditions that T is 3 seconds and T is not less than 3 are not met, the routine returns.
5. The small-current grounding error-selection-preventing method based on five-time phase ground incremental current according to claim 1, characterized in that the step fifthly comprises the following steps:
(5.1) when the fault is judged to be the earth fault, calculating and enabling the half cycle phase earth incremental current of the non-fault phase of the 8 th power frequency cycle after the fault to be corresponding to a set value I8SComparing; (5.2) when the increment is larger than the set value I8SCalculating the initial phase of the phase-to-ground incremental current of two non-fault phases and the phase difference delta theta between the two phases8The program leads in a phase difference comparison section; otherwise, the incremental three-phase comparison section is led in; (5.3) when the program is introduced into the phase difference comparison section, the delta theta is calculated8With a set angle value theta8SIn comparison, when | Δ θ |8| is less than θ8SIf so, confirming that the phase is a fault line fault phase; when | Δ θ8| is not less than θ8SIf yes, confirming the fault as non-grounding or non-leakage fault, and returning the program; (5.4) when the program is introduced into the incremental three-phase comparison section, respectively calculating incremental currents of a fault phase in the 8 th week after the fault and a half-cycle phase of a non-fault phase, and comparing the incremental currents with the incremental currents; when the current of the fault phase is larger than the current K of the non-fault phase8SWhen the voltage is doubled, the fault is determined to be grounding or leakage fault; otherwise the program returns.
6. The small-current grounding fault-line-selection-prevention method based on the five-tense phase-ground incremental current according to claim 4, wherein the step sixteenth comprises the following steps:
and (3) carrying out subsequent fault state monitoring by each grounding monitor sending a fault report: (6.1) calculating the three-phase current sampling accumulated value after 5 seconds of fault
Wherein the subscript j is the sampling times which are accumulated after 5 seconds of failure; (6.2) calculating the phase-to-ground incremental current value I5 seconds after the faultAH-IAQ＝IAGH、IBH-IBQ＝IBGH、ICH-ICQ＝ICGH(ii) a (6.3) comparing the delta current values of the three phases, when the fault phase is detected, the value is respectively greater than K of the values of the other two phasesHSWhen the current is doubled, the grounding or leakage fault is reported to be continuous; otherwise, the phase-to-phase earth incremental current value of the earth phase is not larger than the value K of the other two phases after 3 seconds of continuous detectionHSIn the case of double condition, the loss of the grounding or leakage fault is reported.
7. The small-current grounding fault-line-selection preventing method based on the five-time phase-to-ground incremental current according to any one of claims 1 to 6, wherein the calculated value of the phase-to-ground incremental current is an accumulated value of absolute values of sampling increments, and comprises calculation of the accumulated value as a half-cycle average value, a full-cycle average value, an amplitude value or an effective value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710405146.8A CN107728000B (en) | 2017-05-31 | 2017-05-31 | Small-current grounding anti-error line selection method based on five-time phase-to-ground incremental current |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710405146.8A CN107728000B (en) | 2017-05-31 | 2017-05-31 | Small-current grounding anti-error line selection method based on five-time phase-to-ground incremental current |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107728000A CN107728000A (en) | 2018-02-23 |
| CN107728000B true CN107728000B (en) | 2021-05-18 |
Family
ID=61201281
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710405146.8A Active CN107728000B (en) | 2017-05-31 | 2017-05-31 | Small-current grounding anti-error line selection method based on five-time phase-to-ground incremental current |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107728000B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109884466B (en) * | 2019-03-04 | 2020-06-26 | 中国矿业大学 | Distribution network grounding line selection method for identifying double negative sequence current vector relation characteristics |
| CN112462201A (en) * | 2020-12-16 | 2021-03-09 | 国网江苏省电力有限公司沛县供电分公司 | Annular power distribution network single-phase earth fault line selection method based on classification and identification |
| CN115792504B (en) * | 2023-01-31 | 2023-05-02 | 国网山西省电力公司电力科学研究院 | Power distribution network single-phase earth fault positioning method and system based on phase current abrupt change |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103809070A (en) * | 2012-11-15 | 2014-05-21 | 施耐德电器工业公司 | Method and device for direction grounding fault detection on basis of three-phase current changes |
| CN103852693A (en) * | 2014-03-26 | 2014-06-11 | 马善娟 | Judging method of small current grounding line selection system |
| CN104614642A (en) * | 2015-01-27 | 2015-05-13 | 国家电网公司 | Small current grounding line selection method |
| CN104808114A (en) * | 2015-05-04 | 2015-07-29 | 中国矿业大学 | Low-current grounding fault line selection method based on wide-area zero-sequence voltage distribution characteristics |
| CN107179481A (en) * | 2017-07-06 | 2017-09-19 | 中国矿业大学 | The fault line selection method for single-phase-to-ground fault of annular isolated neutral power distribution network |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012069175A (en) * | 2010-09-21 | 2012-04-05 | Renesas Electronics Corp | Semiconductor device |
| US9911492B2 (en) * | 2014-01-17 | 2018-03-06 | International Business Machines Corporation | Writing multiple levels in a phase change memory using a write reference voltage that incrementally ramps over a write period |
-
2017
- 2017-05-31 CN CN201710405146.8A patent/CN107728000B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103809070A (en) * | 2012-11-15 | 2014-05-21 | 施耐德电器工业公司 | Method and device for direction grounding fault detection on basis of three-phase current changes |
| EP2733498A2 (en) * | 2012-11-15 | 2014-05-21 | Schneider Electric Industries SAS | Method and device for detecting directional grounding fault based on three phase current variation |
| CN103852693A (en) * | 2014-03-26 | 2014-06-11 | 马善娟 | Judging method of small current grounding line selection system |
| CN104614642A (en) * | 2015-01-27 | 2015-05-13 | 国家电网公司 | Small current grounding line selection method |
| CN104808114A (en) * | 2015-05-04 | 2015-07-29 | 中国矿业大学 | Low-current grounding fault line selection method based on wide-area zero-sequence voltage distribution characteristics |
| CN107179481A (en) * | 2017-07-06 | 2017-09-19 | 中国矿业大学 | The fault line selection method for single-phase-to-ground fault of annular isolated neutral power distribution network |
Non-Patent Citations (3)
| Title |
|---|
| A fault line selection algorithm using neural network based on S-transform energy;Hongchun Shu.et al;《2010 Sixth International Conference on Natural Computation》;20100923;第1478-1482页 * |
| 偏磁式消弧线圈自动跟踪补偿装置及配套选线装置在电网中的应用;王玮 等;《冶金电流》;20051225(第6期);第40-41页 * |
| 矿井配电网单相接地故障选线与定位新方法;宗伟林 等;《工矿自动化》;20161130;第42卷(第11期);第45-49页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107728000A (en) | 2018-02-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN100386637C (en) | Fault line selection method for single-phase-to-ground fault in small ground current distribution network | |
| CN111398733B (en) | Ocean nuclear power platform power grid ground fault line selection protection method and system | |
| CN107102236B (en) | A kind of fault line selection method for single-phase-to-ground fault based on waveform correlation analysis after failure | |
| CN107728000B (en) | Small-current grounding anti-error line selection method based on five-time phase-to-ground incremental current | |
| CN109494696B (en) | Power distribution network asymmetric fault positioning and isolating method and system based on adaptive reclosing | |
| CN111308272B (en) | Positioning method for low-current ground fault section | |
| AU2019271889B1 (en) | Single-phase-to-ground fault line selection method for distribution lines and computer readable storage medium | |
| WO2019127440A1 (en) | Method and device for handling direct current arc | |
| CN104316819B (en) | Small current grounding line selection method based on zero-sequence currents | |
| CN110221178A (en) | The fault wire selection method and device of single-phase grounded malfunction in grounded system of low current | |
| CN109888729A (en) | A kind of early warning type transformer protection method and device | |
| CN112485588A (en) | Permanent high-resistance fault section positioning method based on cascade H-bridge control | |
| CN104577999A (en) | Bus protection method and system based on transient-state zero-sequence current characteristic | |
| CN110783896A (en) | Distribution network single-phase grounding protection method based on weak fault active and passive joint detection | |
| CN110221115B (en) | Method, device and equipment for determining single-phase grounding capacitance current | |
| CN102097792A (en) | Ground fault protection method of distribution network | |
| Bountouris et al. | MV faulted section location in distribution systems based on unsynchronized LV measurements | |
| Shen | A novel method of fault line selection in low current grounding system using multi-criteria information integrated | |
| CN112379302B (en) | Small-current ground fault protection method, device and system for integrating time-frequency domain information | |
| CN107632237A (en) | A kind of fault line selection method for single-phase-to-ground fault based on wavelet character amount correlation after failure | |
| Zerihun et al. | Two novel current-based methods for locating earth faults in unearthed ring operating MV networks | |
| Velayudham et al. | Locating ground fault in distribution systems using smart meter | |
| CN112649694B (en) | Method for judging single-phase grounding fault of low-current grounding system | |
| WO2021158809A1 (en) | High impedance fault detector | |
| CN2783338Y (en) | Small current grounding line selector |
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 | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20231023 Address after: 221116 Research Institute of China University of Mining and Technology, Tongshan University Road, Xuzhou City, Jiangsu Province Patentee after: CHINA University OF MINING AND TECHNOLOGY Address before: 221116 Research Institute of China University of Mining and Technology, Tongshan University Road, Xuzhou City, Jiangsu Province Patentee before: CHINA University OF MINING AND TECHNOLOGY Patentee before: SHENZHEN JINPA ELECTRIC POWER TECHNOLOGY CO.,LTD. |
|
| TR01 | Transfer of patent right |