CN112904237B - Phase selection positioning method for single-phase grounding fault of hydraulic generator based on current difference - Google Patents
Phase selection positioning method for single-phase grounding fault of hydraulic generator based on current difference Download PDFInfo
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- CN112904237B CN112904237B CN202110376092.3A CN202110376092A CN112904237B CN 112904237 B CN112904237 B CN 112904237B CN 202110376092 A CN202110376092 A CN 202110376092A CN 112904237 B CN112904237 B CN 112904237B
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- 238000004804 winding Methods 0.000 claims description 33
- 238000010187 selection method Methods 0.000 abstract description 7
- 238000004088 simulation Methods 0.000 abstract description 3
- 230000007547 defect Effects 0.000 abstract description 2
- 238000012986 modification Methods 0.000 description 2
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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
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Abstract
The invention discloses a single-phase earth fault phase selection positioning method of a hydraulic generator based on a current difference value, which comprises the following steps: (1) Measuring the current of each camera end side and the neutral point side of the fault generator; (2) Taking the absolute value of the difference between the two current values measured by each phase; (3) Comparing the magnitudes of three absolute values, wherein the phase where the numerical current with larger difference from the other two numerical values is located is the fault phase; (4) Using PSPICE simulation to measure fault phase current difference values when the fault points are at different distances from the neutral point position, and making a line graph; (5) And (3) according to the curve position of the difference value measured in the step (1), corresponding to the position of the fault point. The invention improves the phase selection accuracy and solves the defect that the traditional phase selection method depending on the minimum value of the zero sequence voltage fundamental wave amplitude can misjudge.
Description
Technical Field
The invention relates to the field of generator relay protection, in particular to a hydro-generator single-phase grounding fault phase selection positioning method based on a current difference value.
Background
Ground faults are one of the most common causes of damage to the generator. The main risk of an earth fault is that the fault current through the breakdown channel may burn the stator magnetic circuit. In order to ensure safe operation of the generator, it is important that the stator ground fault protection trips rapidly after the ground fault is detected. However, a sudden trip of a large generator as a main power source will seriously affect the safe operation of the power system. Therefore, from the point of view of the power system, tripping of the large generator should be avoided as much as possible.
The fault phase discrimination and fault position determination of the single-phase grounding of the stator of the hydraulic generator are important links for perfecting the grounding fault protection scheme of the existing generator, and can greatly reduce the fault maintenance work. The rapid detection of the stator single-phase earth fault can greatly reduce the occurrence probability of the internal fault of the generator, and if the fault phase can be continuously judged and the specific fault position can be checked, the method can provide great help for the subsequent treatment of the generator stator earth fault.
In the prior fault phase selection method, a low-voltage phase selection method is generally adopted to realize fault phase selection, and the phase with the lowest amplitude is judged as the fault phase by comparing the voltage amplitudes of three camera ends of the hydraulic generator. However, subsequent analysis shows that the lowest phase of the voltage amplitude of the machine end is greatly influenced by the grounding modes of different neutral points and the grounding transitional resistance, and when the single phase of the stator passes through a high-resistance grounding fault and the fault position is close to the neutral point, the method has low sensitivity and the possibility of phase selection by mistake. Another phase selection method is a fault phase selection method which uses the next phase (according to the phase sequence of a-B-C) of the phase with the highest amplitude of the voltage at the machine terminal as the fault phase: for example, assuming a B-phase ground fault, if the a-camera terminal voltage amplitude is measured to be maximum, it is indicated that the B-phase fault occurs. However, for a turbo generator using a winding with a multi-branch structure, when a branch winding with a phase potential later than the winding potential has a high-resistance fault, the amplitude of the machine-side voltage is the highest as the B phase, so that the phase selection method may also have a wrong phase selection.
Disclosure of Invention
The invention aims to: the invention provides a single-phase grounding fault phase selection positioning method of a hydraulic generator based on current difference values. The method can effectively solve the problems that the sensitivity is very low and even the phase is erroneously selected when the phase selection of the stator ground fault is realized by utilizing the amplitude value of the three-phase voltage of the generator terminal in the past.
In order to achieve the above purpose, the technical scheme provided by the invention is as follows:
a hydro-generator single-phase earth fault phase selection positioning method based on current difference value comprises the following steps:
firstly, measuring current IA at a position of an A-phase winding of the fault generator, which is close to a neutral point, and current IA' at a position of the A-phase winding, which is close to a machine end, and taking difference to obtain an absolute value of the A-phase current difference as follows: a= |i A -I A ′|；
Secondly, measuring the current I of the B-phase winding of the fault generator near the neutral point B Current I at the position of B-phase winding close to machine end B ' taking the difference between the two to obtain the absolute value of the B phase current difference as follows: b= |i B -I B ′|；
Finally measure the causeCurrent I of C-phase winding of barrier generator near neutral point C Current I at the position of C-phase winding close to machine end C ' taking the difference between the two to obtain the absolute value of the C-phase current difference as follows: c= |i C -I C ′|；
Comparing the sizes of a, b and c to obtain a phase with the maximum value NAX { a, b and c }, namely a fault phase;
then, a distributed parameter model of the hydraulic generator is established by using PSPICE simulation software, and the current difference value of each phase of the fault phase and the sound phase stator winding when the fault point is at different fault positions is measured;
and further making a corresponding curve on the coordinate axis to obtain a line graph, and searching one ordinate position corresponding to the measured three-phase current difference values a, b and c on the line graph to obtain a corresponding fault position point.
The beneficial effects are that: compared with the prior art, the invention has the following advantages:
the invention provides a single-phase grounding fault phase selection positioning method of a hydraulic generator based on current difference values. The invention improves the phase selection positioning accuracy and solves the defect that the traditional phase selection method depending on the minimum value of the zero-sequence voltage fundamental wave amplitude can misjudge.
Drawings
FIG. 1 is a schematic diagram of a phase A phase-through resistor ground fault of a stator winding according to the present invention;
FIG. 2 is a graph of a distributed parameter model in PSPICE simulation;
FIG. 3 is a plot of the difference curves for each phase current at different fault point locations.
Detailed Description
The following describes the implementation of the present invention in detail with reference to the drawings.
The invention provides a single-phase grounding fault phase selection positioning method of a hydro-generator based on current difference, which is shown in figure 1, and is assumed that a phase A of the hydro-generator has a grounding fault at a position which is far from a neutral point alpha of a stator windingThe windings from the neutral point to the fault point in the phase A are the percentage of the total windings, R f Is the fault point ground resistance. In the figure, E a 、E b 、E c Respectively represent the electromotive forces of three phases of the stator winding A, B, C of the generator, C A 、C B 、C C The ground capacitances of the three-phase stator windings of the generator A, B, C are respectively represented, and R is the value of the ground resistance of the hydraulic generator in a high-resistance grounding mode.
Fig. 2 is a distribution parameter model of the hydraulic generator in the PSPICE simulation software. The rated parameters of the hydraulic generator are set as follows: the rated power is 550MW, the rated voltage is 18KV, the capacitance to ground of each phase of the stator winding is 1.686 mu F, the resistance of each phase of the stator is 3.6mΩ, the leakage inductance of each phase of the stator is 227.05 mu H, and the rated frequency is 50Hz. In the figure, each branch circuit consists of four series unit circuits, and the capacitance to ground of each phase winding of the stator is divided into four parts: the phase A is C1-C4, the phase B is C5-C8, and the phase C is C9-C12; each phase of leakage inductance of the stator is divided into four parts: the phase A is L1-L4, the phase B is L5-L8, and the phase C is L9-L12; the resistance of each phase of the stator is divided into four parts: the phase A is R1-R1, the phase B is R5-R8, and the phase C is R9-R12; the distribution induced electromotive force is divided into four parts: the phase A is U1-U4, the phase B is U5-U8, and the phase C is U9-U12; r is the neutral point grounding resistance of the hydraulic generator, and the value is 629.3 omega; r is R f The value of the grounding resistance of the fault point is 50Ω. Assuming that a single-phase ground fault occurs in the A phase, the reference data of the table 1 are obtained through simulation of different fault point positions.
TABLE 1
And further, making corresponding curves of the table on the coordinate axes to obtain a line graph as shown in fig. 3, wherein the line graph shows the current difference values at two ends of the stator winding of each phase corresponding to different fault point positions alpha when the A phase is in fault grounding.
The fault phase selection positioning steps are as follows:
(1) First, the current I of the phase winding of the fault generator A near the neutral point is measured A Current I at the position of A-phase winding close to machine end A ' it is added withThe two are subjected to difference, and the absolute value of the obtained A-phase current difference is as follows: a= |i A -I A ′|；
(2) Secondly, measuring the current I of the B-phase winding of the fault generator near the neutral point B Current I at the position of B-phase winding close to machine end B ' taking the difference between the two to obtain the absolute value of the B phase current difference as follows: b= |i B -I B ′|；
(3) Finally, measuring the current I of the C-phase winding of the fault generator near the neutral point C Current I at the position of C-phase winding close to machine end C ' taking the difference between the two to obtain the absolute value of the C-phase current difference as follows: c= |i C -I C ′|；
(4) Comparing the magnitudes of a, b and c to obtain a maximum value MAX { a, b and c } which is the fault phase;
(5) And further making a corresponding curve on the coordinate axis to obtain a line graph, and searching one ordinate position corresponding to the measured three-phase current difference values a, b and c on the line graph to obtain a corresponding fault position point.
The above examples are only preferred embodiments of the present invention, it being noted that: it will be apparent to those skilled in the art that several modifications and equivalents can be made without departing from the principles of the invention, and such modifications and equivalents fall within the scope of the invention.
Claims (1)
1. The single-phase earth fault phase selection positioning method for the hydraulic generator based on the current difference value is characterized by comprising the following steps of:
(1) Measuring current I of A phase winding of fault generator near neutral point A Current I at the position of A-phase winding close to machine end A ' taking the difference between the two to obtain the absolute value of the A-phase current difference as follows: a= |i A -I A ′|；
(2) Then, the current I of the B-phase winding of the fault generator near the neutral point is measured B Current I at the position of B-phase winding close to machine end B ' taking the difference between the two to obtain the absolute value of the B phase current difference as follows: b= |i B -I B ′|；
(3) Finally, measuring the current I of the C-phase winding of the fault generator near the neutral point C Current I at the position of C-phase winding close to machine end C ' taking the difference between the two to obtain the absolute value of the C-phase current difference as follows: c= |i C -I C ′|；
(4) Comparing the magnitudes of a, b and c to obtain a maximum value MAX { a, b and c } which is the fault phase;
(5) Establishing a hydro-generator distribution parameter model by using PSPICE simulation software, and measuring current difference values at two ends of a fault phase stator winding at different fault positions;
(6) Further making a corresponding curve on the coordinate axis to obtain a line graph, and searching a ordinate position corresponding to each measured phase current difference value a, b and c on the line graph to obtain a corresponding fault position point;
in the step (4), the difference value of currents at two ends of the stator winding of the fault phase is the largest; in the step (6), there may be an error between the difference between the currents at the two ends of the stator winding of the actually faulty phase and the curve, and then the nearest position point on the curve is selected.
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| CN202110376092.3A CN112904237B (en) | 2021-04-08 | 2021-04-08 | Phase selection positioning method for single-phase grounding fault of hydraulic generator based on current difference |
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| CN101819252A (en) * | 2009-11-23 | 2010-09-01 | 电子科技大学 | Analog-circuit fault diagnosis method |
| CN104655977A (en) * | 2014-12-19 | 2015-05-27 | 华北电力大学（保定） | Generator exciting winding short-circuit fault diagnosis method based on torque comparison principle |
| CN104793171A (en) * | 2015-04-23 | 2015-07-22 | 广西电网有限责任公司电力科学研究院 | Fault simulation based smart meter fault detection method |
| CN108469573A (en) * | 2018-03-21 | 2018-08-31 | 国网河南省电力公司漯河供电公司 | A kind of method that small current neutral grounding system utilizes error component phase selection |
| CN109239524A (en) * | 2018-07-16 | 2019-01-18 | 海南电网有限责任公司电力科学研究院 | A kind of low current method for locating single-phase ground fault based on three-phase current amplitude |
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2021
- 2021-04-08 CN CN202110376092.3A patent/CN112904237B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101819252A (en) * | 2009-11-23 | 2010-09-01 | 电子科技大学 | Analog-circuit fault diagnosis method |
| CN104655977A (en) * | 2014-12-19 | 2015-05-27 | 华北电力大学（保定） | Generator exciting winding short-circuit fault diagnosis method based on torque comparison principle |
| CN104793171A (en) * | 2015-04-23 | 2015-07-22 | 广西电网有限责任公司电力科学研究院 | Fault simulation based smart meter fault detection method |
| CN108469573A (en) * | 2018-03-21 | 2018-08-31 | 国网河南省电力公司漯河供电公司 | A kind of method that small current neutral grounding system utilizes error component phase selection |
| CN109239524A (en) * | 2018-07-16 | 2019-01-18 | 海南电网有限责任公司电力科学研究院 | A kind of low current method for locating single-phase ground fault based on three-phase current amplitude |
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