CN114720904A - Method and device for positioning single-phase earth fault position of generator stator winding - Google Patents

Method and device for positioning single-phase earth fault position of generator stator winding Download PDF

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CN114720904A
CN114720904A CN202110967299.8A CN202110967299A CN114720904A CN 114720904 A CN114720904 A CN 114720904A CN 202110967299 A CN202110967299 A CN 202110967299A CN 114720904 A CN114720904 A CN 114720904A
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phase
fault
generator
stator winding
voltage
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裴丽秋
李华忠
陶振国
张琦雪
杨洪涛
王洪林
许林波
孟自磊
赵慧勉
李阳
吴礼军
方浩
吴成忠
方贤永
王光
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Fengtai Power Generation Branch Of Huaizhe Electric Power Co ltd
NR Engineering Co Ltd
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Fengtai Power Generation Branch Of Huaizhe Electric Power Co ltd
NR Engineering Co Ltd
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    • 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
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • 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
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/72—Testing of electric windings
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52—Outage or fault management, e.g. fault detection or location

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Abstract

The invention discloses a method and a device for positioning a single-phase earth fault position of a generator stator winding, wherein the method comprises the steps of firstly, calculating a zero-sequence loop characteristic parameter according to a generator group ground capacitance, a generator neutral point grounding transformer and a secondary load resistance parameter thereof; calculating a corresponding central angle between the head coil and the tail coil of the single branch of the stator winding according to the fundamental wave potential phase difference of the adjacent series coils of the single branch of the stator winding of the generator and the total number of turns of the series coils of the single branch; then, three-phase fundamental voltage and fundamental zero-sequence voltage at the generator end are calculated by adopting three-phase voltage data at the generator end, a fault phase is judged, and fundamental voltage of the fault phase is recorded; and calculating a fault angle corresponding to the fault position from the neutral point of each branch to the fault position according to the fault phase fundamental wave voltage, the fundamental wave zero-sequence voltage, the zero-sequence loop characteristic parameters and the central angle, and finally calculating the ratio of the fault angle to the central angle, namely the grounding position. The method is independent of injection type stator grounding protection, is simple and easy to implement, and is accurate.

Description

Method and device for positioning single-phase earth fault position of generator stator winding
Technical Field
The invention relates to relay protection and fault location of a large synchronous generator of a power system, in particular to a stator winding single-phase earth fault location technology of the large synchronous generator.
Background
The positioning of the grounding fault position of the stator winding of the large synchronous generator is always a hotspot difficulty of research in the industry. The traditional manual checking method comprises a pressurization observation method, a segmentation method, a direct current bridge method, an open transformer method and the like, the grounding position can be well positioned by adopting the comprehensive judgment of the method, but the conditions of long time consumption, low checking efficiency, more trial and error times and the like exist, and especially for the generator with more stator slots, the longer the time consumption is, the larger the generated energy loss is. While the relay protection equipment which usually adopts the principles of fundamental zero sequence voltage, third harmonic ratio or injected low-frequency signals and the like is already mature and applied on site, the relay protection equipment does not have the function of positioning the position of the stator ground fault. Selective stator grounding protection based on a zero sequence direction is proposed in documents such as selective stator grounding protection research and application based on a flexible optical mutual inductor, large-scale generators and generator end external element single-phase grounding fault positioning, and the like, although the grounding protection based on the zero sequence direction can distinguish whether a grounding fault occurs inside or outside a generator stator, the troubleshooting efficiency is improved to a certain extent, but the positioning of the grounding position of a stator winding cannot be realized. For the single-phase earth fault and protection of the stator, they are discussed in detail in some professional books, for example, see the editions of relay protection principle and application of electrical main equipment (second edition), wang wei, wo 2002, china electric power press. For the generator stator winding partial discharge online monitoring device, although the partial discharge signal quantity change can be monitored in real time, and the conductor insulation reduction condition can be monitored in real time, the stator winding ground fault position positioning function can not be realized. Therefore, how to quickly locate the grounding position and improve the investigation efficiency is a problem to be solved urgently on site and to be concerned by users.
Besides the conventional method, there are some methods for positioning the single-phase earth fault position of the stator winding, and there are three methods. One method is disclosed in patent ZL200410006176.4 "single-phase grounding protection and fault location method for stator winding of generator", and the other method is disclosed in thesis "single-phase grounding fault location method for stator independent of injection principle", chenjun, liu catalpol, wang mingxi, etc. "" power system automation "" (2013) 04, and in patent CN201810238653.1 "single-phase grounding fault location method for stator winding of generator".
The first method is dependent on injection type stator ground protection, and is based on a T-shaped equivalent circuit of a generator neutral point grounding transformer, the resistance value of a ground fault transition resistor is calculated and obtained, then three-phase fundamental wave voltage and fundamental wave zero sequence voltage at the generator end are measured in an actual mode, and the position of a ground fault is calculated by combining the equivalent circuit. The method has the advantages that the calculation is relatively accurate theoretically; the method has the defect of being seriously dependent on the accuracy of parameters, wherein the parameters comprise three-phase ground capacitance parameters of the stator side of the generator, T-shaped equivalent circuit parameters of a neutral grounding transformer, load resistance parameters and grounding fault transition resistance parameters. In practical application, if parameters provided by equipment manufacturers are used, the calculation error ratio is larger, if the parameters are actually measured data, the actually measured workload is large, the actually measured workload comprises the actually measured three-phase ground capacitance parameters, the actually measured T-shaped equivalent circuit parameters of the neutral grounding transformer need to be measured for short-circuit impedance and excitation impedance respectively, and the actually measured load resistance is measured; in addition, when a serious ground fault close to the machine end occurs, the resistance value of the ground transition resistor measured by the injection stator ground protection is inaccurate due to the fact that the voltage and current signals measured by the injection stator ground protection have large power frequency components at the same time. This method is not applicable to cases where there is no injection stator ground protection, such as when the generator neutral is not grounded or grounded via an arc suppression coil. These factors all limit the application of this method.
In the second method, three-phase fundamental voltage and fundamental zero-sequence voltage at the generator end are measured actually, and then calculation is carried out according to a simplified equivalent formula to obtain the position of the ground fault. The method has the advantages that the grounding transition resistance value measured by the injection type stator grounding protection is not needed, T-shaped equivalent circuit parameters of the grounding transformer are not needed, in the calculation process, the phasor relation of three-phase fundamental wave voltage and fundamental wave zero sequence voltage is fully utilized, the grounding transition resistance value can be substantially calculated, and therefore the grounding fault position is finally obtained. The method has the disadvantages that the formula is over simplified, calculation errors are introduced when T-shaped equivalent parameters of the grounding transformer are omitted, and particularly, certain errors exist in calculation results under the conditions that the grounding transformer has larger difference with an ideal transformer and the relevant T-shaped equivalent parameters cannot be ignored.
In the third method, the fundamental wave zero sequence voltage under the fault conditions is calculated on the assumption that the tail end of each line bar has a ground fault, and is compared with the fundamental wave zero sequence voltage of the actual fault to judge the fault position, so that the positioning accuracy can be well improved, but the calculation amount is large, and the method can not be realized in an embedded platform device.
Disclosure of Invention
In order to solve the problems, the invention provides a method for positioning a single-phase earth fault position of a generator stator winding, which comprises the following steps:
calculating a zero-sequence loop characteristic parameter according to a generator group ground capacitance, a generator neutral point grounding transformer and a secondary load resistance parameter thereof;
calculating a corresponding central angle between head and tail coils of a single branch of the stator winding according to the fundamental wave potential phase difference of adjacent series coils of the single branch of the generator stator winding and the total number of turns of the single branch series coils;
step three, adopting generator terminal voltage data, calculating three-phase fundamental wave voltage and fundamental wave zero sequence voltage at the generator terminal, if the effective value of the fundamental wave zero sequence voltage is smaller than a set fixed value threshold, finishing the judgment of the stator winding single-phase earth fault position location, otherwise entering the step four;
judging a fault phase of the single-phase earth fault of the stator winding, and recording the fundamental wave voltage of the corresponding fault phase;
fifthly, according to fault phase fundamental wave voltage, fundamental wave zero sequence voltage, zero sequence loop characteristic parameters and a central angle; calculating a corresponding fault angle from each branch neutral point to a fault position;
and step six, calculating the ratio of the fault angle to the central angle, namely the grounding position.
Optionally, the zero-sequence loop characteristic parameter of the step one includes ReqAnd XCeq(ii) a Wherein R iseqIs equivalent resistance, X, of generator stator winding side to ground under the condition of no faultCeqThe equivalent capacitive reactance of the generator stator winding side to the ground under the power frequency under the condition of no fault is calculatedThe formula is as follows:
Figure BDA0003224591820000031
Figure BDA0003224591820000032
in the formula, Rk、XkRespectively a primary value of short-circuit resistance and a primary value of short-circuit reactance of a generator neutral point grounding transformer, RNFor the secondary load resistance of the generator neutral grounding transformer to the resistance value of the primary side, RN＝K2rnK is the transformer ratio of the generator neutral point grounding transformer, rnSecondary load resistance, X, of generator neutral point grounding transformerCThe stator winding is connected with the ground capacitor and other equipment on the machine end in parallel with the stator winding is connected with the ground capacitor.
Optionally, the central angle β of the initial step two is calculated by the following formula:
β＝N·β1formula (3)
In the formula, beta1And N is the total number of turns of the single-branch series coil.
Optionally, after three-phase voltage data at the generator end is read or acquired in the third step, a full-cycle fourier series calculation method is adopted to calculate three-phase fundamental voltage
Figure BDA0003224591820000041
And fundamental zero sequence voltage
Figure BDA0003224591820000042
If the fundamental wave zero sequence voltage effective value U0Less than a set constant threshold U0,setJudging whether the single-phase grounding fault position of the stator winding is positioned or not; the three-phase voltage data at the generator end of the generator is read or collected through a generator end III of a generator protection device or a fault recording devicePhase voltage waveform data or real-time data of three-phase voltage at the generator end are acquired; the set constant value threshold U0,setThe value range is 1% -20% of the effective value of the rated phase voltage of the generator.
Optionally, the specific method for determining the fault phase of the single-phase ground fault of the stator winding in the fourth step is as follows: when the neutral point of the generator is not grounded or is grounded through the arc suppression coil, the three-phase fundamental voltage is obtained according to the ABC phase sequence
Figure BDA0003224591820000043
The next phase of the largest effective value of (a) is a failed phase; when the neutral point of the generator is grounded through a high resistance, the three-phase fundamental voltage
Figure BDA0003224591820000044
The phase with the smallest effective value of (a) is the failed phase; recording a faulted phase as
Figure BDA0003224591820000045
Optionally, the method for calculating the fault angle corresponding to the fault location from the neutral point of each branch in the step five includes:
γ1＝π-γRX-γN1-γE1formula (4)
In the formula, gamma1A fault angle is corresponding to a fault position from a neutral point of the branch 1, and pi is a radian corresponding to an angle of 180 degrees;
γRXthe calculation formula is as follows:
Figure BDA0003224591820000046
in the formula, ReqIs equivalent resistance, X, of the generator stator winding side to the ground under the condition of no faultCeqIs no reason
The equivalent capacitive reactance of the generator stator winding side to the ground under the condition of fault is generated;
γN1the calculation formula is as follows:
Figure BDA0003224591820000047
wherein β is a central angle;
Figure BDA0003224591820000048
is composed of
Figure BDA0003224591820000049
And
Figure BDA00032245918200000410
phase angle difference between them, setting three-phase fundamental voltage according to ABC phase sequence
Figure BDA00032245918200000411
When the neutral point of the generator is not grounded or is grounded through the arc suppression coil,
Figure BDA00032245918200000412
the next phase of the largest effective value of (a) is a failed phase;
when the generator neutral point is connected to ground via a high impedance,
Figure BDA0003224591820000051
the phase with the smallest effective value of (a) is a fault phase, and the fault phase is recorded as
Figure BDA0003224591820000052
Is fundamental wave zero sequence voltage;
γE1the calculation formula is as follows:
Figure BDA0003224591820000053
Figure BDA0003224591820000054
Figure BDA0003224591820000055
in the formula (I), the compound is shown in the specification,
Figure BDA0003224591820000056
optionally, the method for calculating the fault angle corresponding to the fault position from the neutral point of each branch in the fifth step includes:
Figure BDA0003224591820000057
in the formula, gamma21、γ22A fault angle is corresponding to the position from the neutral point of the branch 2 to the fault position, and pi is a radian corresponding to the angle of 180 degrees;
γRXthe calculation formula is as follows:
Figure BDA0003224591820000058
in the formula, ReqIs equivalent resistance, X, of generator stator winding side to ground under the condition of no faultCeqThe equivalent capacitive reactance is generated under the condition of no fault under the power frequency of the generator stator winding side to the ground;
γN2the calculation formula is as follows:
Figure BDA0003224591820000059
wherein β is a central angle;
Figure BDA00032245918200000510
is composed of
Figure BDA00032245918200000511
And
Figure BDA00032245918200000512
phase angle difference between them, setting three-phase fundamental voltage according to ABC phase sequence
Figure BDA00032245918200000513
When the neutral point of the generator is not grounded or is grounded through the arc suppression coil,
Figure BDA00032245918200000514
the next phase of the largest effective value of (a) is a failed phase;
when the generator neutral point is connected to ground via a high impedance,
Figure BDA0003224591820000061
the phase with the smallest effective value of (A) is a failed phase, and the failed phase is recorded as
Figure BDA0003224591820000062
Is fundamental wave zero sequence voltage;
γE21、γE22the calculation formula is as follows:
Figure BDA0003224591820000063
Figure BDA0003224591820000064
Figure BDA0003224591820000065
in the formula (I), the compound is shown in the specification,
Figure BDA0003224591820000066
optionally, the calculation formula of the ratio of each fault angle to the central angle in the sixth step is as follows:
Figure BDA0003224591820000067
in the formula, gamma1A corresponding fault angle is formed from a neutral point of the branch 1 to a fault position; beta is a central angle;
or
Figure BDA0003224591820000068
In the formula, gamma21、γ22Corresponding to the fault angle for the neutral point of branch 2 to the fault location.
The invention also provides a generator stator winding single-phase earth fault position locating device, which comprises:
an initial calculation unit: calculating a zero sequence loop characteristic parameter according to the parameters of the generator group ground capacitance, the generator neutral point grounding transformer and the secondary load resistance thereof; calculating a corresponding central angle between head and tail coils of a single branch of the stator winding according to the fundamental wave potential phase difference of adjacent series coils of the single branch of the generator stator winding and the total number of turns of the single branch series coils;
a collecting unit: collecting the voltage at the generator end, the three-phase fundamental voltage and the fundamental zero-sequence voltage at the computer end, if the effective value of the fundamental zero-sequence voltage is smaller than a set fixed value threshold, finishing the judgment of the single-phase earth fault position positioning of the stator winding, otherwise, entering a positioning calculation unit;
a positioning calculation unit: judging a fault phase of the single-phase earth fault of the stator winding, and recording the fundamental wave voltage of the corresponding fault phase; according to the fault phase fundamental wave voltage, the fundamental wave zero sequence voltage, the zero sequence loop characteristic parameters and the central angle; calculating a corresponding fault angle from each branch neutral point to a fault position; and calculating the ratio of the fault angle to the central angle, namely the grounding position.
The invention has the beneficial effects that:
(1) compared with the traditional method depending on the injection type stator grounding protection, the method is simpler, the injection type stator grounding protection is not needed, and the zero-sequence loop characteristic parameters can be calculated only by providing the generator group grounding capacitance, the generator neutral point grounding transformer and the secondary load resistance parameters thereof;
(2) compared with the traditional method which does not depend on injection type stator grounding protection, the method is more accurate, solves the problem of calculation error caused by neglecting parameters such as a neutral point grounding transformer and the like, and greatly reduces the calculation amount due to simple calculation steps;
(3) the phasor relation of fundamental voltage of each coil bar of the stator is fully considered, and the particularity of the ground fault inside the stator winding of the generator motor is considered: the fundamental voltage from the ground fault point to the neutral point of the generator and the fundamental voltage from the generator end to the neutral point of the generator have phase deviation, so that the fault location calculation is more accurate;
(4) compared with the prior art, the method is simultaneously suitable for various grounding modes such as ungrounded neutral points, grounding through arc suppression coils, high-resistance grounding and the like of the generator, and has wider application range.
Drawings
FIG. 1 is a schematic diagram of a generator stator winding single phase ground fault;
FIG. 2 is a block diagram of the calculations of the present invention;
FIG. 3 is a block diagram of the earth fault location positioning device of the present invention;
FIG. 4 is a fundamental equivalent circuit diagram in the case of a single-phase earth fault of a stator winding;
FIG. 5 is a geometric diagram of the anisotropy of a branch 1 in the case of a single-phase earth fault of a stator winding;
fig. 6 is a geometric diagram of the anisotropy of the branch 2 in the case of a single-phase earth fault of the stator winding.
Detailed Description
For the purpose of illustrating the method of the invention in a clear manner, reference is made to the accompanying drawings which illustrate specific embodiments of the invention.
FIG. 1 is a schematic diagram of a generator stator winding single-phase ground fault, wherein GEN is a generator, F is a fault point of the stator winding single-phase ground fault, O is a generator neutral point, NGT is a neutral grounding transformer, and R'nIs a load resistor, R, on the low-voltage side of the grounding transformerFIs the earth transition resistance of the single-phase earth fault of the stator winding, CA、CB、CCThe capacitors are respectively the A relative ground capacitor, the B relative ground capacitor and the C relative ground capacitor at the side of the stator winding of the generator, the capacitors are actually distributed capacitors, and the capacitors simplified into centralized parameters are placed at the generator end. Distributed capacitance of generator GEN three-phase stator winding to ground is equivalent to concentrated capacitance parameter CA、CB、CCIs placed at the machine end; the generator GEN neutral point O is grounded through a grounding transformer NGT, the low-voltage side of the grounding transformer is connected with a load resistor rn(ii) a When a single-phase earth fault occurs at a certain position F of the generator GEN stator A-phase winding, the insulation failure at the earth fault position can be equivalent to that the insulation failure starts from a fault point and passes through an earth transition resistor RFAnd (4) grounding.
The invention provides a method for positioning a single-phase earth fault position of a stator winding of a generator, and further improves the positioning precision of the single-phase earth fault position of the stator winding. Now, taking a certain 660MW steam turbine generator unit parameter and ground fault in China as an example, a specific implementation mode is described, and the steps are shown in fig. 2.
Example (c): the capacity of the generator is 733MVA, the frequency is 50Hz, the primary rated voltage is 20kV, the single-phase-to-ground capacitance C of the stator of the generator is 0.2815uF, the neutral point of the generator adopts a grounding mode of grounding transformer and secondary load resistor grounding, namely a high-resistance grounding mode, the capacity of the grounding transformer is 50kVA, the transformation ratio is 20kV/0.22kV, the short-circuit loss is 0.127kW, the short-circuit voltage percentage is 7.326 percent, and the secondary load resistance value r of the grounding transformer isn0.465 omega, the generator stator winding single branch adjacent series coil fundamental wave potential phase difference beta14.286 degrees, the total turn number N of the single branch series coil is 14, the rated phase voltage secondary value of the generator is 57.74V, and the fixed threshold U0,set5.19% × 57.74 ═ 3V. Assuming that a single-phase earth fault occurs in a stator winding of the generator at a certain moment, a device applying the method of the invention is selected for fault location analysis, and the device composition is shown in fig. 3.
Firstly, an initial calculation unit calculates a zero-sequence loop characteristic parameter according to a generator group grounding capacitance or a generator neutral point grounding transformer and a secondary load resistance parameter thereof; the characteristic parameter refers to R in figure 4eqAnd XCeqFIG. 4 is a fundamental equivalent circuit diagram in the case of a single-phase earth fault of a stator winding; in the figure, ReqIs equivalent resistance, X, of generator stator winding side to ground under the condition of no faultCeqIs equivalent capacitive reactance R under the power frequency of the generator stator winding side to the ground under the condition of no faultFIs a single-phase earth fault of the stator windingA transition resistance to ground is set in the circuit,
Figure BDA0003224591820000081
is the fundamental wave zero sequence voltage at the generator end,
Figure BDA0003224591820000082
the fundamental voltage from a single-phase earth fault point of a stator winding to a neutral point of a generator is calculated by the following formula:
Figure BDA0003224591820000083
Figure BDA0003224591820000091
wherein R isk、XkRespectively a primary value of short-circuit resistance and a primary value of short-circuit reactance of a generator neutral point grounding transformer, RNFor the secondary load resistance of the generator neutral grounding transformer to the resistance value of the primary side, RN＝K2rnK is the transformer ratio of the generator neutral point grounding transformer rnSecondary load resistance, X, of generator neutral point grounding transformerCThe stator winding is connected with the ground capacitor and other equipment on the machine end in parallel with the stator winding is connected with the ground capacitor.
The initial calculation unit calculates a corresponding central angle between head and tail coils of a single branch of the stator winding according to the fundamental wave potential phase difference of adjacent series coils of the single branch of the stator winding of the generator and the total turns of the series coils of the single branch, and the central angle beta is calculated by the following formula:
Figure BDA0003224591820000092
wherein beta is1And N is the total number of turns of the single-branch series coil.
Generator terminal III acquired by acquisition unitPhase voltage data, adopting a Fourier series calculation method of full cycle, calculating three-phase fundamental voltage as,
Figure BDA0003224591820000093
Figure BDA0003224591820000094
and fundamental zero sequence voltage
Figure BDA0003224591820000095
Effective value of known fundamental wave zero sequence voltage
Figure BDA0003224591820000096
Greater than set fixed value threshold U0,setAnd entering a positioning calculation unit when the voltage is 3V.
The positioning calculation unit judges the fault phase of the single-phase earth fault of the stator winding and records the fundamental wave voltage of the corresponding fault phase; when the neutral point of the generator is grounded through a high resistance, the three-phase fundamental voltage
Figure BDA0003224591820000097
Is a failed phase, wherein the effective value of the A-phase fundamental wave voltage is 54.33V, and the lowest effective value of the three-phase fundamental wave voltage, the A-phase is determined as the failed phase, and the failed phase is recorded as the failed phase
Figure BDA0003224591820000098
The method for calculating the fault angle corresponding to the neutral point of each branch to the fault position comprises the following steps of:
Figure BDA0003224591820000101
wherein the geometric relationship of the anisotropy is shown in FIG. 5, γ1Corresponding to a fault angle from a neutral point of a branch 1 to a fault position, wherein pi is an angle 180Radian corresponding to degree;
γRXthe calculation formula is as follows:
Figure BDA0003224591820000102
γN1the calculation formula is as follows:
Figure BDA0003224591820000103
Figure BDA0003224591820000104
is composed of
Figure BDA0003224591820000105
And
Figure BDA0003224591820000106
the phase angle difference between them; gamma rayE1The calculation formula is as follows:
Figure BDA0003224591820000107
Figure BDA0003224591820000108
Figure BDA0003224591820000111
Figure BDA0003224591820000112
further, a fault angle corresponding to a neutral point to a fault position of each branch is calculated, and the method for calculating the fault angle corresponding to the neutral point to the fault position of each branch comprises the following steps:
Figure BDA0003224591820000113
where the geometric relationship of the anisotropy is shown in FIG. 6, and γ21、γ22A corresponding fault angle is formed from a neutral point of the branch 2 to a fault position;
γRXthe calculation formula is as follows:
Figure BDA0003224591820000114
γN2the calculation formula is as follows:
Figure BDA0003224591820000115
Figure BDA0003224591820000116
is composed of
Figure BDA0003224591820000117
And
Figure BDA0003224591820000118
the phase angle difference between them;
γE2the calculation formula is as follows:
Figure BDA0003224591820000119
Figure BDA0003224591820000121
Figure BDA0003224591820000122
Figure BDA0003224591820000123
Figure BDA0003224591820000124
the positioning calculation unit calculates the ratio of the fault angle to the central angle, namely the ratio alpha of each fault angle to the central angle,
the calculation formula is as follows:
Figure BDA0003224591820000125
or
Figure BDA0003224591820000126
The method is simultaneously suitable for the mode that the neutral point of the generator is not grounded, is grounded through an arc suppression coil or is grounded through a high resistance.
The above embodiments are merely illustrative of the technical ideas of the present invention, and the technical ideas of the present invention can not be used to limit the scope of the present invention.

Claims (9)

1. A method for positioning a single-phase earth fault position of a generator stator winding is characterized by comprising the following steps:
calculating a zero-sequence loop characteristic parameter according to a generator group ground capacitance, a generator neutral point grounding transformer and a secondary load resistance parameter thereof;
calculating a corresponding central angle between head and tail coils of a single branch of the stator winding according to the fundamental wave potential phase difference of adjacent series coils of the single branch of the generator stator winding and the total number of turns of the single branch series coils;
step three, collecting generator terminal voltage data, and calculating a three-phase fundamental wave voltage and a fundamental wave zero sequence voltage at a generator terminal, if an effective value of the fundamental wave zero sequence voltage is smaller than a set fixed value threshold, finishing the judgment of the stator winding single-phase earth fault position location, otherwise, entering the step four;
judging a fault phase of the single-phase earth fault of the stator winding, and recording the fundamental wave voltage of the corresponding fault phase;
fifthly, according to fault phase fundamental wave voltage, fundamental wave zero sequence voltage, zero sequence loop characteristic parameters and a central angle; calculating a corresponding fault angle from each branch neutral point to a fault position;
and step six, calculating the ratio of the fault angle to the central angle, namely the grounding position.
2. The method as claimed in claim 1, wherein the zero sequence characteristic parameters in the first step include ReqAnd XCeq(ii) a Wherein R iseqIs equivalent resistance, X, of generator stator winding side to ground under the condition of no faultCeqThe equivalent capacitive reactance of the generator stator winding side to the ground under the power frequency condition under the condition of no fault is calculated by the following formula:
Figure FDA0003224591810000011
Figure FDA0003224591810000012
in the formula, RK、XKRespectively a primary value of short-circuit resistance and a primary value of short-circuit reactance of a generator neutral point grounding transformer, RNFor the secondary load resistance of the generator neutral grounding transformer to the resistance value of the primary side, RN＝K2rnK is the transformer ratio of the generator neutral point grounding transformer rnSecondary load resistance, X, of generator neutral point grounding transformerCBeing the stator winding itselfThe capacitance to ground and other equipment at the terminal connected in parallel with the capacitance to ground.
3. The method for locating the position of the single-phase ground fault of the stator winding of the generator according to claim 1, wherein the central angle β of the second step is calculated by the formula:
β＝N·β1formula (3)
In the formula, beta1And N is the total number of turns of the single-branch series coil.
4. The method for locating the position of a single-phase ground fault of a stator winding of a generator according to claim 1, wherein after three-phase voltage data at a generator terminal is read or collected in the third step, a full-cycle Fourier series calculation method is adopted to calculate the three-phase fundamental voltage
Figure FDA0003224591810000021
And fundamental zero sequence voltage
Figure FDA0003224591810000022
If the fundamental wave zero sequence voltage effective value U0Less than a set threshold U0,setJudging whether the single-phase grounding fault position of the stator winding is positioned or not; the read or collected generator end three-phase voltage data is obtained by reading generator end three-phase voltage waveform data of a generator protection device or a fault wave recording device or collecting generator end three-phase voltage real-time data; the set constant value threshold U0,setThe value range is 1% -20% of the effective value of the rated phase voltage of the generator.
5. The method for locating the single-phase ground fault position of the stator winding of the generator according to claim 1, wherein the specific method for determining the fault phase of the single-phase ground fault of the stator winding in the fourth step is as follows: when the generator neutral point is not grounded or is grounded through the arc suppression coilThree-phase fundamental voltage according to ABC phase sequence
Figure FDA0003224591810000023
The next phase of the largest effective value of (a) is a failed phase; when the neutral point of the generator is grounded through a high resistance, the three-phase fundamental voltage
Figure FDA0003224591810000024
The phase that is the smallest of the effective values of (a) is a failed phase; recording a faulted phase as
Figure FDA0003224591810000025
6. The method for locating the position of the single-phase ground fault of the stator winding of the generator according to claim 1, wherein the step five of calculating the corresponding fault angle from the neutral point of each branch to the fault position comprises the following steps:
γ1＝π-γRX-γN1-γE1formula (4)
In the formula, gamma1A fault angle is corresponding to a fault position from a neutral point of the branch 1, and pi is a radian corresponding to an angle of 180 degrees; gamma rayRXThe calculation formula is as follows:
Figure FDA0003224591810000026
in the formula, ReqIs equivalent resistance, X, of generator stator winding side to ground under the condition of no faultCeqThe equivalent capacitive reactance is generated under the condition of no fault under the power frequency of the generator stator winding side to the ground;
γN1the calculation formula is as follows:
Figure FDA0003224591810000031
wherein, beta is a central angle,
Figure FDA0003224591810000032
is composed of
Figure FDA0003224591810000033
And
Figure FDA0003224591810000034
phase angle difference between them, setting three-phase fundamental voltage according to ABC phase sequence
Figure FDA0003224591810000035
When the neutral point of the generator is not grounded or is grounded through the arc suppression coil,
Figure FDA0003224591810000036
the next phase of the largest effective value of (a) is a failed phase; when the generator neutral point is connected to ground via a high impedance,
Figure FDA0003224591810000037
the phase with the smallest effective value of (a) is a fault phase, and the fault phase is recorded as
Figure FDA0003224591810000038
Figure FDA0003224591810000039
Is fundamental wave zero sequence voltage;
γE1the calculation formula is as follows:
Figure FDA00032245918100000310
Figure FDA00032245918100000311
Figure FDA00032245918100000312
in the formula (I), the compound is shown in the specification,
Figure FDA00032245918100000313
7. the method for locating the position of the single-phase ground fault of the stator winding of the generator according to claim 1, wherein the step five of calculating the corresponding fault angle from the neutral point of each branch to the fault position comprises the following steps:
Figure FDA00032245918100000314
in the formula, gamma21、γ22A fault angle is corresponding to the position from the neutral point of the branch 2 to the fault position, and pi is a radian corresponding to the angle of 180 degrees;
γRXthe calculation formula is as follows:
Figure FDA00032245918100000315
in the formula, ReqIs equivalent resistance, X, of generator stator winding side to ground under the condition of no faultCeqThe equivalent capacitive reactance is generated under the condition of no fault under the power frequency of the generator stator winding side to the ground;
γN2the calculation formula is as follows:
Figure FDA0003224591810000041
wherein, beta is a central angle,
Figure FDA0003224591810000042
is composed of
Figure FDA0003224591810000043
And
Figure FDA0003224591810000044
phase angle difference between them, setting three-phase fundamental voltage according to ABC phase sequence
Figure FDA0003224591810000045
When the neutral point of the generator is not grounded or is grounded through the arc suppression coil,
Figure FDA0003224591810000046
the next phase of the largest effective value of (a) is a failed phase; when the generator neutral point is connected to ground via a high impedance,
Figure FDA0003224591810000047
the phase with the smallest effective value of (a) is a fault phase, and the fault phase is recorded as
Figure FDA0003224591810000048
Figure FDA0003224591810000049
Is fundamental wave zero sequence voltage;
γE21、γE22the calculation formula is as follows:
Figure FDA00032245918100000410
Figure FDA00032245918100000411
Figure FDA00032245918100000412
in the formula (I), the compound is shown in the specification,
Figure FDA00032245918100000413
8. the method for locating the position of the single-phase ground fault of the stator winding of the generator according to claim 1, wherein the calculation formula of the ratio of each fault angle to the central angle in the sixth step is as follows:
Figure FDA00032245918100000414
in the formula, gamma1A corresponding fault angle from a neutral point of the branch 1 to a fault position, wherein beta is a central angle;
or
Figure FDA0003224591810000051
In the formula, gamma21、γ22Corresponding to the fault angle for the neutral point of branch 2 to the fault location.
9. A single-phase ground fault location device for a generator stator winding, the device comprising:
an initial calculation unit: calculating characteristic parameters of a zero-sequence loop according to the grounding capacitance of the generator set, the neutral point grounding transformer of the generator and secondary load resistance parameters of the neutral point grounding transformer; calculating a corresponding central angle between head and tail coils of a single branch of the stator winding according to the fundamental wave potential phase difference of adjacent series coils of the single branch of the generator stator winding and the total number of turns of the single branch series coils;
a collecting unit: collecting the voltage at the generator end, the three-phase fundamental voltage and the fundamental zero-sequence voltage at the computer end, if the effective value of the fundamental zero-sequence voltage is smaller than a set fixed value threshold, finishing the judgment of the single-phase earth fault position positioning of the stator winding, otherwise, entering a positioning calculation unit;
a positioning calculation unit: judging a fault phase of the single-phase earth fault of the stator winding, and recording the fundamental wave voltage of the corresponding fault phase; calculating a fault angle corresponding to the neutral point of each branch to the fault position according to the fundamental wave voltage, the fundamental wave zero-sequence voltage, the zero-sequence loop characteristic parameters and the central angle of the fault phase; and calculating the ratio of the fault angle to the central angle, namely the grounding position.
CN202110967299.8A 2021-08-23 2021-08-23 Method and device for positioning single-phase earth fault position of generator stator winding Pending CN114720904A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116047355A (en) * 2022-12-28 2023-05-02 山东理工大学 Grounding transformer operation condition on-line detection method based on high-voltage side current signal
CN116148709A (en) * 2022-12-28 2023-05-23 中国长江电力股份有限公司 Large-scale generator stator ground fault branch judgment method
CN116184260A (en) * 2022-12-13 2023-05-30 清华大学 Large-scale generator stator ground fault positioning optimization method based on graphic method

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116184260A (en) * 2022-12-13 2023-05-30 清华大学 Large-scale generator stator ground fault positioning optimization method based on graphic method
CN116184260B (en) * 2022-12-13 2023-09-15 清华大学 Large-scale generator stator ground fault positioning optimization method based on graphic method
CN116047355A (en) * 2022-12-28 2023-05-02 山东理工大学 Grounding transformer operation condition on-line detection method based on high-voltage side current signal
CN116148709A (en) * 2022-12-28 2023-05-23 中国长江电力股份有限公司 Large-scale generator stator ground fault branch judgment method
CN116047355B (en) * 2022-12-28 2023-12-05 山东理工大学 Grounding transformer operation condition on-line detection method based on high-voltage side current signal
CN116148709B (en) * 2022-12-28 2024-03-29 中国长江电力股份有限公司 Large-scale generator stator ground fault branch judgment method

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