CN112787318B - Setting method for stage type zero sequence overcurrent protection of small resistance grounding system - Google Patents
Setting method for stage type zero sequence overcurrent protection of small resistance grounding system Download PDFInfo
- Publication number
- CN112787318B CN112787318B CN201911165359.3A CN201911165359A CN112787318B CN 112787318 B CN112787318 B CN 112787318B CN 201911165359 A CN201911165359 A CN 201911165359A CN 112787318 B CN112787318 B CN 112787318B
- Authority
- CN
- China
- Prior art keywords
- iii
- protection
- zero sequence
- iii1
- iiik
- 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
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/08—Limitation or suppression of earth fault currents, e.g. Petersen coil
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/006—Calibration or setting of parameters
Landscapes
- Emergency Protection Circuit Devices (AREA)
Abstract
A method for setting stage type zero sequence over-current protection of a grounding system through a small resistor belongs to the field of relay protection of a power distribution network. For the power distribution network grounded by a small resistor, no matter how large the transition resistance is when single-phase grounding fault occurs, the zero sequence current of the fault line is far larger than that of the sound line, so that the selectivity of grounding protection can be realized by utilizing the transverse cooperation among the outgoing line protection. The invention provides a method for setting stage type zero sequence overcurrent protection of a grounding system through a small resistor based on transverse matching, which mainly comprises a starting current setting method, a protection stage number setting method, a setting method of fixed values of all stages, an action time limit setting method and the like.
Description
Technical Field
The invention relates to a setting method for ground fault protection of a small-resistance grounding system, which is suitable for a power distribution system with a neutral point grounded through a small resistor and belongs to the field of relay protection of a power distribution network.
Background
The neutral point is grounded through a small resistor, so that the grounding device has the advantages of being capable of quickly cutting off grounding faults, low in overvoltage level, capable of eliminating resonance overvoltage, capable of adopting cables and electrical equipment with lower insulation level, convenient to operate and maintain and the like, and is applied to more and more power distribution networks in large cities. Because the amplitude of the zero sequence current is not changed greatly when single-phase grounding occurs at different positions on the line, selective action cannot be realized generally through the cooperation of a zero sequence current protection fixed value, and the grounding current does not exceed 1000A and has small damage to a system, the on-site zero sequence (III section) overcurrent protection is basically only adopted at a fixed time limit, and the cooperation with the protection of a downstream branch line and a distribution transformer is realized through action time limit.
However, due to the fact that 10kV distribution lines are deep into dense personnel areas and are affected by factors such as natural environment and low overhead distance of the lines, single-phase high-resistance ground faults of non-ideal conductors, such as leads falling on grasslands, roads, sand lands, ponds and the like, often occur. The current constant value (3 times zero sequence current constant value, the same below) of zero sequence overcurrent protection of a 10kV small-resistance grounding power distribution network in China is generally 40-60A, and only grounding resistance of about 85-135 omega can be detected to the maximum. Therefore, the high-resistance grounding will be refused, and the long-time fault operation of the system may cause the protection action of the grounding transformer to cut off the power supply or the interphase short circuit fault, thereby enlarging the fault range and the damage.
The existing high-resistance grounding fault detection algorithm of the small-resistance grounding system is mainly divided into two types: the method is based on harmonic or distortion information and adopts a method of analyzing tools such as pattern recognition, and the electric quantity such as power frequency zero sequence current/voltage generated by ground fault is utilized to form ground protection. Compared with the traditional timing zero sequence overcurrent protection, the sensitivity of the two methods is improved, the former method is more suitable for the condition that the grounding point is unstable, and the latter method is simpler, more convenient and more reliable in setting configuration and easier to realize on site.
The invention provides a step-type zero sequence overcurrent protection setting method suitable for a small resistance grounding system according to the characteristic that the zero sequence current of a fault outgoing line in the small resistance grounding system is always far larger than the zero sequence current of a healthy outgoing line and by combining the traditional step-type zero sequence overcurrent protection thought.
Disclosure of Invention
The invention provides a staged zero-sequence overcurrent protection setting method suitable for a small-resistance grounding system by combining the characteristics of the traditional staged zero-sequence overcurrent protection, and the sensitivity of high-resistance grounding fault protection can be effectively improved.
The technical solution of the invention is as follows:
a method for setting step-type zero-sequence over-current protection of small-resistance grounding system mainly comprises a starting current I S Setting method, protective segment number k setting method, IIIX/IIIX' segment constant value I set.ⅢX /I’ set.ⅢX (IIIX is the protection of each section of an outlet wire, IIIX' is the protection of each section of a grounding transformer, and X is 1,2,3 … k) and an operation time limit setting method.
Further, a starting current I S The setting method comprises the following steps: starting current I S The maximum value of the maximum unbalanced zero sequence current of the system and the minimum precision current of the zero sequence current transformer is taken.
Further, the method for setting the number k of the protection segments comprises the following steps: considering the existence of zero sequence TA measurement error, in order to avoid the measured value of the zero sequence current of the healthy outgoing line and the measured value of the zero sequence current of the fault outgoing line being in the same section no matter whether the measured values are in the same sectionWhether the protection is outgoing line protection or grounding transformer protection, the difference between the upper limit and the lower limit of the fixed value of each section of current should not exceed 1/(omega R) N C 0n K rel 2 ) Multiple (omega is power frequency angular frequency, R) N Is neutral point resistance, C 0n For each outgoing line maximum zero sequence capacitance, K rel 1.2-1.3) is generally taken as a reliability coefficient, and if the zero sequence current of a fault line and a neutral point does not exceed alpha when a single-phase earth of the power distribution network is assumed 1 A, the number k of the protective segments should satisfy [1/(ω R) N C 0n K rel 2 )] k ＞α 1 /I S The smallest integer value of (c).
Further, IIIX/IIIX' sections define the value I set.ⅢX /I’ set.ⅢX The setting method comprises the following steps:
1) the section III 1/III 1' is the highest section of the algorithm, and only needs to ensure that the current fixed value of the section avoids the maximum zero sequence current of the sound circuit when the single phase is grounded under any condition, and the zero sequence current of the sound circuit is supposed not to exceed alpha 2 A, then I set.Ⅲ1 ≥K rel ×α 2 ，I’ set.Ⅲ1 ≥K rel ×I set.Ⅲ1 ；
2) The IIIk/IIIk' section is the lowest section of the algorithm, I set.Ⅲk Starting current constant value I capable of being set as protection S I.e. I set.Ⅲk ＝I S Considering the existence of zero sequence TA measurement error, I 'is taken to avoid override action for protection start of grounding transformer' set.Ⅲk ＝K rel ×I S ；
3) The III 2/III 2 '-III (k-1)/III (k-1)' section is the middle section of the algorithm, and the difference between the upper limit and the lower limit of the current constant value of each section should not exceed 1/omega R N C 0n K rel 2 Multiple, then I set.Ⅲ2 ～I set.Ⅲ(k-1) It should satisfy:
I’ set.Ⅲ(x-1) ＝K rel ×I set.Ⅲ(x-1) 。
further, when actingThe limiting and setting method comprises the following steps: let t set.Ⅲ1 、t set.Ⅲ2 、…、t set.Ⅲk Respectively limiting values for the corresponding action time of each section of outgoing line protection; t' set.Ⅲ1 、t’ set.Ⅲ2 、…、t’ set.Ⅲk And respectively limiting values for the grounding transformer to protect the corresponding action time of each section. Considering that the minimum action time limit value should be matched with the grounding protection of a lower branch line or a distribution transformer and also should be matched with the grounding protection of a secondary side circuit breaker of an upper main transformer, the return time of the protection device is supposed to be delta t, so t set.Ⅲ1 Is more than or equal to 2 delta t. At the same time, the time step between each section of protection should also be above 2 Deltat, i.e. t set.Ⅲ2 、t set.Ⅲ3 …t set.Ⅲk It should satisfy:
the action time limit of the grounding transformer protection is satisfied: t is t set.Ⅲ(x+1) >t’ set.Ⅲx ≥t set.Ⅲx +Δt。
Drawings
FIG. 1 is a schematic diagram of a ground fault and protection installation position of a low-resistance grounding system;
FIG. 2 shows a step-wise zero-sequence overcurrent protection characteristic;
FIG. 3 is a zero sequence voltage current waveform when grounded through a 100 Ω resistor;
figure 4 is a waveform of zero sequence voltage current when a wire falls to wet grassland and is grounded.
Detailed Description
The invention will be further described with reference to the following drawings and examples:
a method for setting stage-type zero-sequence overcurrent protection of small-resistance grounding system is suitable for power distribution network with neutral point grounded via small resistance, and mainly includes starting current I S Setting method, protective segment number k setting method, IIIX/IIIX' segment constant value I set.ⅢX /I’ set.ⅢX (X is 1,2,3 … k) setting method and operation time limit setting method. Typical topology and protection installation position of small-resistance grounding power distribution network (P1E)Pn、PR N Respectively, each outlet ground protection and grounding transformer protection) as shown in figure 1.
The starting current I S The setting method can perform the following setting calculation in a 10kV low-resistance grounding system:
(1) when the system operates normally, protection is required to prevent misoperation. Starting current constant I of the protection S The maximum unbalanced zero sequence current of the system needs to be higher to prevent the ground protection misoperation when the system normally operates. Generally, the maximum unbalanced zero-sequence currents of an overhead line and a cable line of a 10kV small resistance grounding system are respectively about 0.37A and 0.26A, and a protection device is generally connected with 3 times of zero-sequence current signals, so that there are constraints: i is S >1.11A；
(2) Secondly, the linear range and the measurement error of the zero sequence TA are considered, and the minimum precision work current of the zero sequence current transformer is generally 0.5 percent of the full range (600A), namely I is generally required to be satisfied S ≥600A×0.5％＝3A；
(3) Finally due to I S The fixed value directly influences the resistance tolerance of the grounding protection, and when a grounding fault occurs in a 10kV small-resistance grounding system through a 1.5k omega resistor, the zero-sequence current of a fault outgoing line is about 3.8A without counting the line impedance. So that it can protect the high-resistance earth fault of about 1.5k omega transition resistance and avoid the maximum unbalanced zero sequence current on the line, so that the starting current I S The setting value may be 3A, i.e. I S ＝3A。
The k setting method for the number of the protection sections can perform the following setting calculation in a 10kV 10 omega small-resistance grounding system:
(1) when metallic earth fault occurs at bus or line outlet, fault current I f ≈3E A /3R N The current is approximately equal to 600A, so that the segmentation is only needed to be carried out in the current range of 3A-600A.
(2) In order to prevent the measured value of the zero-sequence current of the healthy outgoing line and the measured value of the zero-sequence current of the fault outgoing line from being positioned in the same section, the difference between the upper limit and the lower limit of the fixed value of each section of current should not exceed 1/omega R no matter the outgoing line protection or the grounding transformer protection is adopted N C 0n K rel 2 Multiple, omega, in a 10kV 10 omega low resistance grounding systemR N C 0n Generally, it can be 0.1, and the number of guard segments K should satisfy (10/K) rel 2 ) k >600/3, take K rel When 1.25, get k>In practical engineering, the more the number of protection stages, the more complex and difficult the setting process and the coordination between upper and lower-stage protection, so k should be the minimum value k equal to 3, that is, the number of protection stages should be three, and it is marked as iii 1, iii 2, and iii 3.
The IIIX/IIIX' stage is of constant value I set.ⅢX /I’ set.ⅢX In a 10kV 10 omega low-resistance grounding system, the setting calculation can be carried out as follows:
(1) the section III 1/III 1' is the highest section of the algorithm, and only the maximum zero sequence current of the sound line in single-phase grounding is needed to be avoided by the current set value of the section (the zero sequence current of the sound line in the current stage of China through a small-resistance grounding system is not more than 60A) under any condition, and then I is set.Ⅲ1 ≥K rel ×60，I’ set.Ⅲ1 ≥K rel ×I set.Ⅲ1 Taking K rel 1.25, can be I set.Ⅲ1 ≥75A，I’ set.Ⅲ1 ≥94A；
(2) Section III 3/III 3' is the lowest section of the algorithm, I set.Ⅲ3 Starting current constant value I capable of being set as protection S I.e. I set.Ⅲ3 ＝I S Considering the existence of zero sequence TA measurement error, I 'to avoid override action for grounding transformer protection startup' set.Ⅲ3 ＝K rel ×I S Taking K rel 1.25, can obtain I' set.Ⅲ3 ＝3.75A；
(3) The III 2/III 2' section is the middle section of the algorithm, and the difference between the upper limit and the lower limit of the current constant value of each section should not exceed 10/K rel 2 Multiple, then I set.Ⅲ2 It should satisfy:
I’ set.Ⅲ2 ＝K rel ×I set.Ⅲ2 . Get K rel 1.25, can obtain 12A<I set.Ⅲ2 <19A. For ground voltage transformationWhen the device is protected, 15A is provided<I’ set.Ⅲ2 <24A。
The action time limit setting method can perform the following setting calculation in a 10kV low-resistance grounding system:
generally, if the return time of protection is more than 0.3s, i.e. Δ t is more than or equal to 0.3s, it is considered that the minimum action timing value should be matched with the ground protection of the lower branch line or distribution transformer, and should also be matched with the ground protection of the secondary side circuit breaker of the upper main transformer, so t is t set.Ⅲ1 Not less than 2 delta t is 0.6s, and the time step between each protection section is more than 2 delta t, i.e. t set.Ⅲ2 、t set.Ⅲ3 It should satisfy:
therefore there is t set.Ⅲ2 ≥1.2s，t set.Ⅲ3 The time limit of the action of the grounding transformer protection is more than or equal to 1.8s, and the action time limit of the grounding transformer protection meets the following requirements: t is t set.Ⅲx+1 >t’ set.Ⅲx ≥t set.Ⅲx + Δ t, then 1.2s>t’ set.Ⅲ1 ≥0.9s、1.8s>t’ set.Ⅲ2 ≥1.5s、t’ set.Ⅲ3 Not less than 2.1 s. The relationship between the fixed value and the action time limit of each section after being set by the invention is shown in figure 2.
Based on the manual grounding experiment result of the second-segment bus of the 110kV ZY transformer substation in a certain city in Shandong province, the beneficial effect of the stage-type zero-sequence over-current protection setting method provided by the invention is verified.
The neutral point of the experimental line is grounded through a 10 omega resistor connected with a grounding transformer, the system has 12 overhead cable mixed outgoing lines in total, and the capacitance current to the ground is 72A. The artificial simulated faults include stable grounding (transition resistances of 4 Ω, 100 Ω, 500 Ω and 1000 Ω respectively) and unstable grounding (arc grounding and wire falling wet grass grounding of 100 Ω resistor series-connected ball gap simulation respectively). The test data of two healthy lines F1 and F2 with the maximum earth capacitance current, one healthy line F3 with the smaller earth capacitance current and a fault line F4 are selected for verification, and the fixed values of the outgoing line ground protection and the bus grounding transformer protection are set according to the method provided by the invention. Zero sequence current of each outgoing line, zero sequence current of a neutral point and action conditions in each fault are shown in table 1, and zero sequence voltage and zero sequence current of each outgoing line when the zero sequence current and the neutral point are grounded through a 100 omega transition resistor and are grounded through grasslands are shown in attached figures 3 and 4.
TABLE 1 effective value and action condition of zero sequence current of each outgoing line
Note: ≈ activation; ↓ -return; trip of hook; x-no start; III 1, III 2 and III 3 are corresponding segment numbers for protection
As is apparent from the data in table 1, when the ground is connected via a 4 Ω resistor (body resistor connected to the ground at the fault point), the ground protection of the fault line F4, the grounding neutral point, and the two lines F1 and F2 with the largest capacitance current to ground will be started at the same time, and since the fault line F4 acts first, the other started but unselective protection after the fault is removed will have enough time to return reliably, and will not malfunction. In other types of ground faults, only the fault line F4 and the neutral point transformer are protected and started, and the zero sequence current of the sound line does not exceed the starting current fixed value I of the protection S Since the robust line protection device is not started up as 3A, the ground transformer protection device is started up together with the faulty line protection device, but the operation time limit thereof is long, so that the device can return after the faulty line protection device is operated, and the device cannot be operated by mistake.
When the high resistance is grounded, such as 1000 omega grounding, the method provided by the invention sets a fixed value, and can still remove the fault for about 1.8 s. For an unstable earth fault, although the waveforms of the zero-sequence voltage and the zero-sequence current are distorted, the protection still acts correctly as long as the measured zero-sequence current is higher than the current constant value of the protection.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (1)
1. A method for setting step-type zero-sequence overcurrent protection of a small-resistance grounding system is suitable for a neutral point passing through the small-resistance grounding system, and comprises a starting current setting method, a protection segment number setting method, a setting method of each segment of fixed value and an action time limit setting method, and is characterized in that:
a. starting current I S Taking the maximum value of the maximum unbalanced zero sequence current of the system and the minimum precision current of the zero sequence current transformer;
b. the number k of the guard segments is taken to satisfy
Where ω is the power frequency angular frequency, R N Is neutral point resistance, C 0n For maximum zero sequence capacitance of each outgoing line, K rel For the reliability factor, take 1.2, α 1 Maximum value of zero sequence current of fault line and neutral point when single-phase earth of power distribution network is adopted, I S Is a starting current;
c. fixed value I of multi-stage timing time-limited zero-sequence overcurrent protection III 1, III 2, III 3 … IIIk of each outgoing line set.Ⅲ1 、I set.Ⅲ2 、I set.Ⅲ3 …I set.Ⅲk And fixed value I 'of multi-stage fixed time limit zero sequence overcurrent protection III 1', III 2 ', III 3' … III k 'of grounding transformer' set.Ⅲ1 、I’ set.Ⅲ2 、I’ set.Ⅲ3 …I’ set.Ⅲk On setting satisfy
1) The section III 1/III 1' is the highest section of the algorithm, and the constant value I set.Ⅲ1 、I’ set.Ⅲ1 Satisfy I set.Ⅲ1 ≥K rel ×α 2 ，I’ set.Ⅲ1 ≥K rel ×I set.Ⅲ1 ，α 2 The maximum value of the zero sequence current of the sound line;
2) the III k/III k' section is the lowest section of the algorithm and is a fixed value I set.Ⅲk 、I’ set.Ⅲk Respectively satisfy I set.Ⅲk ＝I S ，I’ set.Ⅲk ＝K rel ×I S ；
3) The sections III 2/III 2 'to III (k-1)/III (k-1)' are middle sections of the algorithm, and the fixed value I set.Ⅲ2 ～I set.Ⅲ(k-1) Respectively satisfy
I’ set.Ⅲ(x-1) ＝K rel ×I set.Ⅲ(x-1) ；
d. Action time limit t of each section of outlet protection set.Ⅲ1 /t’ set.Ⅲ1 、t set.Ⅲ2 /t’ set.Ⅲ2 、…、t set.Ⅲk /t’ set.Ⅲk Satisfying t at tuning set.Ⅲ1 Not less than 2 delta t, the delta t is the return time of the protection device, and 0.3s and t are taken set.Ⅲ2 、t set.Ⅲ3 …t set.Ⅲk Respectively satisfy
The action time limit of each section of protection of the grounding transformer meets t set.Ⅲ(x+1) >t’ set.Ⅲx ≥t set.Ⅲx +Δt。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911165359.3A CN112787318B (en) | 2019-11-25 | 2019-11-25 | Setting method for stage type zero sequence overcurrent protection of small resistance grounding system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911165359.3A CN112787318B (en) | 2019-11-25 | 2019-11-25 | Setting method for stage type zero sequence overcurrent protection of small resistance grounding system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112787318A CN112787318A (en) | 2021-05-11 |
| CN112787318B true CN112787318B (en) | 2022-09-13 |
Family
ID=75749230
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911165359.3A Active CN112787318B (en) | 2019-11-25 | 2019-11-25 | Setting method for stage type zero sequence overcurrent protection of small resistance grounding system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112787318B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114675104A (en) * | 2022-03-22 | 2022-06-28 | 李景禄 | Method for isolation field test and parameter check of targeted zero sequence protection fault region |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108321780A (en) * | 2018-03-19 | 2018-07-24 | 中国石油大学(华东) | It is a kind of to protect the small resistance grounding system inverse time lag zero sequence excess current earthing protecting method laterally coordinated based on each outlet |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102969695B (en) * | 2012-10-26 | 2014-12-17 | 江苏汉天星配电自动化科技有限公司 | Grounding forecasting method in neutral-point low-resistance grounding mode |
| CN105140897B (en) * | 2015-09-26 | 2018-01-26 | 中国石油大学(华东) | A kind of guard method suitable for small resistance grounding system singlephase earth fault |
| CN108899879B (en) * | 2018-07-25 | 2019-07-19 | 国网湖北省电力有限公司电力科学研究院 | Small resistance grounding system earthing protecting method based on zero-sequence current projection coefficient |
-
2019
- 2019-11-25 CN CN201911165359.3A patent/CN112787318B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108321780A (en) * | 2018-03-19 | 2018-07-24 | 中国石油大学(华东) | It is a kind of to protect the small resistance grounding system inverse time lag zero sequence excess current earthing protecting method laterally coordinated based on each outlet |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112787318A (en) | 2021-05-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN106908693B (en) | Single-phase grounding route selection method of arc suppression coil grounding system with high accuracy | |
| CN103207352B (en) | Route selection impedance magnitude characteristic is utilized to realize wire selection method for power distribution network single phase earthing failure | |
| CN102944813B (en) | Resonant grounding system fault line selection method based on reactive power flow directions | |
| CN104111403A (en) | Microcomputer integrated protection line-selection method for low-current earthed power system | |
| CN103207354B (en) | Maximum line selection coefficient principle based single-phase earth fault line selection method for power distribution network | |
| CN105098748A (en) | Surge protector and method for enhancing temporary overvoltage endurance thereof | |
| CN102361321A (en) | 110/220 kV transformers' neutral point grounding via small reactance | |
| CN110768206B (en) | Single-phase earth fault protection method for small-resistance earth system | |
| EP3369150A1 (en) | Method and system for protection in a mixed line | |
| Gajare et al. | Synchrophasor-based intelligent autoreclosing scheme for series compensated transmission lines | |
| CN113484672B (en) | Small-resistance grounding system single-phase grounding fault protection method based on ground wire current | |
| CN108845223A (en) | A kind of arc suppression coil magnetic control disturbance selection method | |
| CN106908692B (en) | A kind of adaptive reclosing judgment method of transmission line one-phase earth fault | |
| Altonen et al. | Performance of modern fault passage indicator concept in compensated MV-networks | |
| CN109239513B (en) | Phase selection method for single-phase earth fault of generator stator winding | |
| CN110824294A (en) | Flexible direct-current power distribution network bipolar short-circuit fault section identification and distance measurement method | |
| CN112787318B (en) | Setting method for stage type zero sequence overcurrent protection of small resistance grounding system | |
| CN112415327B (en) | Cable distribution network fault section identification method based on grounding wire current direction difference | |
| CN112269064A (en) | Power distribution network earth leakage resistance measurement system and method | |
| CN101556300B (en) | Detection method of incorrect tripping caused by ground current invasion to differential analog channel | |
| CN108254650B (en) | Quick judgment method for single-phase earth fault of substation bus | |
| CN114113913A (en) | Single-phase high-resistance grounding fault determination and protection method and device for small-resistance grounding system | |
| CN112649694B (en) | Method for judging single-phase grounding fault of low-current grounding system | |
| CN114878965A (en) | Ground fault positioning method applied to electric power field | |
| Orságová et al. | Earth fault analysis using measured data from fault experiments in actual distribution network |
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 |