CN111751667A - Method and system for judging current transformer saturation based on power grid fault recording diagram - Google Patents
Method and system for judging current transformer saturation based on power grid fault recording diagram Download PDFInfo
- Publication number
- CN111751667A CN111751667A CN202010604663.XA CN202010604663A CN111751667A CN 111751667 A CN111751667 A CN 111751667A CN 202010604663 A CN202010604663 A CN 202010604663A CN 111751667 A CN111751667 A CN 111751667A
- Authority
- CN
- China
- Prior art keywords
- waveform
- fault
- phase
- transmission line
- current waveform
- 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.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0007—Frequency selective voltage or current level measuring
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/175—Indicating the instants of passage of current or voltage through a given value, e.g. passage through zero
-
- 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
-
- 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
- H02H3/24—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 responsive to undervoltage or no-voltage
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
- H02H7/042—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers for current transformers
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Locating Faults (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention provides a method for judging the saturation of a current transformer based on a power grid fault oscillogram, which comprises the steps of obtaining a power transmission line fault oscillogram, wherein the power transmission line fault oscillogram is provided with a three-phase current waveform, a three-phase voltage waveform of a bus, a zero-sequence current waveform and a zero-sequence voltage waveform; if the three-phase current waveform of the power transmission line and the three-phase voltage waveform of the bus are mutated, determining that the fault of the power transmission line exists; obtaining a distorted current waveform formed by any phase mutation in three-phase current waveforms of the power transmission line, drawing a corresponding sine waveform along the distorted current waveform, and taking a zero crossing point of the distorted current waveform and the sine waveform on any half-cycle wavelength simultaneously to calculate the time difference between the two zero crossing points; and if the time difference is within the preset time difference range, judging that the iron core of the current transformer has a saturation defect. The method and the device do not need excessive mathematical calculation, are simple and intuitive, save time and labor, and can solve the problem that field technicians cannot quickly judge the saturation phenomenon of the current transformer.
Description
Technical Field
The invention relates to the technical field of relay protection, in particular to a method and a system for judging current transformer saturation based on a power grid fault oscillogram.
Background
With the increasing capacity of the power system, the short-circuit current also increases, and the short-circuit current with large amplitude is easy to appear, so that the iron core of the current transformer is saturated to different degrees under the steady state of short circuit.
The iron core of the current transformer has a nonlinear characteristic due to material factors, and once the primary current is large or the primary current contains a large direct-current component, the iron core of the current transformer is saturated, so that the exciting current is increased by dozens of times or even hundreds of times, and the waveform of the secondary current is seriously distorted and distorted. In particular, the current transformer has a large working error under the condition that the iron core is deeply saturated, the waveform of the secondary current of the current transformer can be seriously distorted (the current waveform and the phase distortion) and can inevitably affect the correct work of the relay protection device, and once the iron core of the current transformer is saturated due to an external fault of a protected device, differential current can be generated in the current differential protection, so that protection misoperation is caused.
In actual work on site, the experience of workers is insufficient, whether the current transformer saturation phenomenon occurs or not cannot be judged in time, the problems are easily understood as protection tripping caused by other problems by mistake, the defects of electrical equipment cannot be timely eliminated, potential safety hazards are buried in stable operation of a power grid, and the power supply reliability of the power grid is influenced
In order to solve the problem that field technicians cannot quickly judge the saturation phenomenon of the current transformer, the inventor provides a method for judging the saturation of the current transformer based on a power grid fault oscillogram, excessive mathematical calculation is not needed, and the method is simple, intuitive, time-saving and labor-saving.
Disclosure of Invention
The technical problem to be solved by the embodiment of the invention is to provide a method for judging the saturation of a current transformer based on a power grid fault oscillogram, which is simple and intuitive, saves time and labor and can solve the problem that field technicians cannot quickly judge the saturation of the current transformer.
In order to solve the above technical problem, an embodiment of the present invention provides a method for determining saturation of a current transformer based on a power grid fault oscillogram, where the method includes the following steps:
acquiring a transmission line fault recording diagram, wherein a transmission line three-phase current waveform, a bus three-phase voltage waveform, a zero-sequence current waveform and a zero-sequence voltage waveform are formed on the transmission line fault recording diagram;
if the three-phase current waveform of the power transmission line and the three-phase voltage waveform of the bus have waveform mutation, determining that the fault of the power transmission line exists;
after the transmission line fault is determined to exist, acquiring any phase current waveform mutation in the three-phase current waveform of the transmission line and a distortion current waveform correspondingly formed after the phase current waveform mutation, drawing a sine waveform with the same period and amplitude as the distortion current waveform along a curve track of the distortion current waveform, and further determining a zero crossing point of the distortion current waveform and the sine waveform on any half period wavelength simultaneously so as to calculate the time difference between the zero crossing point of the distortion current waveform and the zero crossing point of the sine waveform;
and if the calculated time difference is within the preset time difference range, judging that the iron core of the current transformer has a saturation defect.
Wherein the method further comprises:
and if the zero sequence current waveform and the zero sequence voltage waveform have waveform mutation when the transmission line fault is determined to exist, determining that the transmission line fault is a ground fault.
Wherein the method further comprises:
acquiring phase lines with waveform mutation in the three-phase current waveform of the power transmission line and the total number of corresponding statistics;
if the total number is one, the transmission line fault is determined to be a single-phase grounding fault, and the obtained phase line with the suddenly changed waveform is set as a fault phase line of the single-phase grounding fault;
if the total number is two, the transmission line fault is determined to be a two-phase interphase short circuit grounding fault, and the two phase lines with the sudden change of the acquired waveform are set as fault phase lines of the two-phase interphase short circuit grounding fault;
and if the total number is three, determining that the transmission line fault is a three-phase interphase short circuit grounding fault, and setting the three phase lines with the sudden change of the acquired waveforms as fault phase lines of the three-phase interphase short circuit grounding fault.
Wherein the method further comprises:
and if the zero-sequence current waveform and the zero-sequence voltage waveform do not have any waveform when the transmission line fault is determined to exist, determining that the transmission line fault is an interphase short-circuit fault, and at least two phase lines with sudden waveform changes in the three-phase current waveforms of the transmission line.
Wherein the method further comprises:
if the number of the phase lines with the sudden waveform changes in the three-phase current waveform of the power transmission line is two, the power transmission line fault is determined to be a two-phase interphase short-circuit fault, and the two phase lines with the sudden waveform changes are set as fault phase lines of the two-phase interphase short-circuit fault;
and if the three phase lines with the sudden change of the waveform in the three-phase current waveform of the power transmission line are three, determining that the fault of the power transmission line is a three-phase interphase short-circuit fault, and setting the three phase lines with the sudden change of the waveform as the fault phase lines with the three-phase interphase short-circuit fault.
Wherein the preset time difference range is [4.3ms, 5ms ].
The embodiment of the invention also provides a system for judging the saturation of the current transformer based on the power grid fault oscillogram, which comprises the following steps:
the device comprises a line fault oscillogram acquisition unit, a data acquisition unit and a data processing unit, wherein the line fault oscillogram acquisition unit is used for acquiring a transmission line fault oscillogram, and a transmission line three-phase current waveform, a bus three-phase voltage waveform, a zero-sequence current waveform and a zero-sequence voltage waveform are formed on the transmission line fault oscillogram;
the power transmission line fault detection unit is used for determining that a power transmission line fault exists if the three-phase current waveform of the power transmission line and the three-phase voltage waveform of the bus have waveform mutation;
the zero crossing point time difference calculation unit is used for acquiring any phase current waveform mutation in the three-phase current waveform of the power transmission line and a distortion current waveform correspondingly formed after the phase current waveform mutation after the power transmission line fault is determined to exist, drawing a sine waveform with the same period and amplitude as the distortion current waveform along a curve track of the distortion current waveform, and further determining the zero crossing point of the distortion current waveform and the sine waveform on any half period wavelength simultaneously so as to calculate the time difference between the zero crossing point of the distortion current waveform and the zero crossing point of the sine waveform;
and the saturation defect judging unit is used for judging that the iron core of the current transformer has the saturation defect if the calculated time difference is within the preset time difference range.
Wherein the preset time difference range is [4.3ms, 5ms ].
Wherein, still include: a ground fault determination unit; wherein the content of the first and second substances,
and the ground fault determination unit is used for determining that the transmission line fault is a ground fault if the zero sequence current waveform and the zero sequence voltage waveform have waveform mutation when the transmission line fault is determined to exist.
Wherein, still include: an inter-phase fault determination unit; wherein the content of the first and second substances,
and the interphase fault determination unit is used for determining that the power transmission line fault is an interphase short-circuit fault if the zero-sequence current waveform and the zero-sequence voltage waveform do not have any waveform when the power transmission line fault is determined to exist, and at least two phase lines with sudden waveform changes in the three-phase current waveforms of the power transmission line are determined.
The embodiment of the invention has the following beneficial effects:
the invention detects whether the transmission line fault exists by identifying whether the transmission line current waveform with mutation exists in the transmission line three-phase current waveform and whether the bus three-phase voltage waveform with mutation exists in the bus three-phase voltage waveform in the transmission line fault oscillogram, and when the transmission line fault exists, by identifying the distorted current waveform formed by any phase current waveform in the three-phase current waveform of the power transmission line and drawing the sine waveform with the same period amplitude along the curve track of the distorted current waveform, comparing the time difference between the zero crossing points of the distorted current waveform and the sine waveform on any half-cycle wavelength at the same time, so as to determine whether the iron core of the current transformer has saturation defects, the whole process does not need excessive mathematical calculation, is simple and visual, and time-saving and labor-saving, and can solve the problem that field technicians cannot quickly judge the saturation phenomenon of the current transformer.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is within the scope of the present invention for those skilled in the art to obtain other drawings based on the drawings without inventive exercise.
Fig. 1 is a flowchart of a method for determining saturation of a current transformer based on a power grid fault oscillogram according to an embodiment of the present invention;
fig. 2 is a transmission line fault oscillogram when a phase-C ground fault occurs in a transmission line in an application scenario of the method for determining saturation of a current transformer based on a power grid fault oscillogram according to the embodiment of the present invention;
fig. 3 is an enlarged schematic view of a distorted current waveform correspondingly formed after a sudden change of the C-phase current waveform of the power transmission line in fig. 2;
fig. 4 is a schematic structural diagram for determining saturation of a current transformer based on a power grid fault oscillogram according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 1, in an embodiment of the present invention, a method for determining saturation of a current transformer based on a power grid fault oscillogram is provided, where the method includes the following steps:
step S1, obtaining a transmission line fault oscillogram, wherein a transmission line three-phase current waveform, a bus three-phase voltage waveform, a zero-sequence current waveform and a zero-sequence voltage waveform are formed on the transmission line fault oscillogram;
step S2, if the three-phase current waveform of the power transmission line and the three-phase voltage waveform of the bus have waveform mutation, determining that the power transmission line has a fault;
step S3, after the transmission line fault is determined to exist, obtaining any phase current waveform mutation in the three-phase current waveform of the transmission line and a distortion current waveform correspondingly formed after the phase current waveform mutation, drawing a sine waveform with the same period and amplitude as the distortion current waveform along the curve track of the distortion current waveform, and further determining the zero crossing point of the distortion current waveform and the sine waveform on any half-period wavelength simultaneously so as to calculate the time difference between the zero crossing point of the distortion current waveform and the zero crossing point of the sine waveform;
and step S4, if the calculated time difference is within the preset time difference range, judging that the iron core of the current transformer has a saturation defect.
In step S1, acquiring a transmission line ground fault recording diagram through a wave recorder and importing the acquired transmission line ground fault recording diagram into computer equipment, so that the computer equipment can call various transmission line ground fault recording diagrams at any time; the transmission line ground fault recording graph comprises, but is not limited to, transmission line three-phase current waveforms, bus three-phase voltage waveforms, zero-sequence current waveforms, zero-sequence voltage waveforms and the like.
In step S2, determining whether there is a sudden change in each phase waveform according to the amplitude change of the three-phase current waveform of the power transmission line and the three-phase voltage waveform of the bus; if the amplitude of a certain phase current waveform is suddenly increased within a certain period of time, namely the position of a peak or a trough on a current curve exceeds the position of the peak or the trough of an original curve, the phase current waveform is determined to have sudden change; and if the amplitude of the waveform of a certain phase voltage suddenly decreases within a certain period of time, namely the position of a peak or a trough on the voltage curve lags behind the peak or the trough of the original curve, the phase voltage waveform is determined to have sudden change.
And if the three-phase current waveform of the power transmission line and the three-phase voltage waveform of the bus have sudden change waveforms, determining that the fault of the power transmission line exists. The amplitude of each phase of power transmission line current waveform which is suddenly changed in the three-phase current waveform of the power transmission line is increased compared with the amplitude of each power transmission line current waveform before sudden change; and the amplitude of each phase bus voltage waveform with sudden change in the bus three-phase voltage waveform is reduced compared with the amplitude of each phase bus voltage waveform before sudden change. If the sudden change of the current waveform of the power transmission line of a certain phase (such as the phase B) in the three-phase current waveforms of the power transmission line is increased, and the sudden change of the voltage waveform of the bus of the same phase (such as the phase B) in the three-phase voltage waveform of the corresponding main bus is reduced, the existence of the fault of the power transmission line is determined.
Furthermore, the type of the transmission line fault, such as a single-phase ground fault, a two-phase interphase short-circuit ground fault, a three-phase interphase short-circuit ground fault, a two-phase interphase short-circuit fault and a three-phase interphase short-circuit fault, is determined by combining whether a sudden change exists in the zero-sequence current waveform and the zero-sequence voltage waveform, and the specific analysis process is as follows:
(1) if the zero-sequence current waveform and the zero-sequence voltage waveform have waveform mutation when the transmission line fault is determined to exist, determining the transmission line fault as a ground fault; wherein the content of the first and second substances,
acquiring a phase line with a waveform mutation in a three-phase current waveform of the power transmission line and the total number of corresponding statistics;
if the total number is one, the transmission line fault is determined to be a single-phase grounding fault, and the obtained phase line with the suddenly changed waveform is set as a fault phase line of the single-phase grounding fault and is one of an A-phase grounding fault, a B-phase grounding fault and a C-phase grounding fault;
if the total number is two, the transmission line fault is determined to be a two-phase interphase short-circuit grounding fault, and the two phase lines with the sudden change of the acquired waveform are set to be fault phase lines of the two-phase interphase short-circuit grounding fault and are one of an AB phase interphase short-circuit grounding fault, a BC phase interphase short-circuit grounding fault and an AC phase interphase short-circuit grounding fault;
and if the total number is three, determining that the transmission line fault is a three-phase interphase short-circuit grounding fault, and setting the three phase lines with the sudden change of the acquired waveforms as fault phase lines of the three-phase interphase short-circuit grounding fault, namely ABC interphase short-circuit grounding fault.
(2) If the transmission line fault is determined to exist, the zero sequence current waveform and the zero sequence voltage waveform do not have any waveform, the transmission line fault is determined to be an interphase short-circuit fault, and at least two phase lines with sudden waveform changes in the three-phase current waveform of the transmission line are determined; wherein the content of the first and second substances,
if the waveform of the three-phase current of the power transmission line is two, determining that the fault of the power transmission line is a two-phase interphase short-circuit fault, and setting the two obtained phase lines with the waveform abrupt change as a fault phase line of the two-phase interphase short-circuit fault, wherein the fault phase line is one of an AB-phase interphase short-circuit fault, a BC-phase interphase short-circuit fault and an AC-phase interphase short-circuit fault;
and if the three phase lines with the sudden change of the waveform in the three-phase current waveform of the power transmission line are three, determining that the fault of the power transmission line is a three-phase interphase short-circuit fault, and setting the three phase lines with the sudden change of the waveform as the fault phase line of the three-phase interphase short-circuit fault, namely the ABC interphase short-circuit fault.
In step S3, after the transmission line fault is determined to exist, the computer device identifies the three-phase current waveforms of the transmission line on the transmission line fault oscillogram, and identifies any phase current waveform mutation in the three-phase current waveforms of the transmission line and a distortion current waveform correspondingly formed after the waveform mutation. It should be noted that the three-phase current waveform, the three-phase voltage waveform, the zero-sequence current waveform and the zero-sequence voltage waveform of the power transmission line all appear in the form of sine waves, and if the current transformer has a saturation defect, distortion influence is generated on the corresponding current waveform of the fault recording diagram of the power transmission line.
Then, in order to distinguish the difference between the distorted current waveform and the normal sine wave, the computer device may draw a sine wave having a period and amplitude equal to the distorted current waveform along a curved trajectory of the distorted current waveform. Of course, the sine wave can also be drawn manually.
And finally, determining the zero crossing point of the distorted current waveform and the sine waveform on any half-cycle wavelength at the same time to calculate the time difference between the zero crossing point of the distorted current waveform and the zero crossing point of the sine waveform, wherein the whole process does not need excessive mathematical calculation, is simple and visual, and saves time and labor.
It should be noted that the zero crossing point refers to a coordinate point where the distorted current waveform or the sinusoidal waveform appears and the waveform amplitude is 0, that is, on the transmission line fault recording diagram, the distorted current waveform or the sinusoidal waveform is read at the first vertical intersection point within the same half-cycle (for example, 10ms) wavelength (at this time, the current amplitude oscillates on both sides of the vertical line), and the two zero crossing points appear at different times, so that a time difference exists. Meanwhile, because a time scale (20ms is a period wavelength) exists on the transmission line fault recording graph, the time difference between the zero crossing point of the distorted current waveform and the zero crossing point of the sinusoidal waveform is calculated by computer equipment or manual work according to the proportion of the distance between the two zero crossing points on the time scale.
In step S4, a time difference range is preset to be [4.3ms, 5ms ], and if the calculated time difference between the zero-crossing point of the distorted current waveform and the zero-crossing point of the sinusoidal waveform is within the time difference range [4.3ms, 5ms ], such that an included angle between the distorted current waveform and the sinusoidal waveform is 72 degrees to 90 degrees, it is determined that the iron core of the current transformer has a saturation defect.
It can be understood that, because the time scale and the wavelength cycle time existing in the transmission line fault oscillogram can be adjusted according to actual needs, the read time difference will be changed correspondingly, and the time difference range is not limited.
As shown in fig. 2 and fig. 3, an application scenario of the method for determining saturation of a current transformer based on a power grid fault oscillogram provided in the embodiment of the present invention is further described:
the power transmission line fault recording diagram comprises a three-phase current I of the power transmission lineA、IB、ICWaveform, bus three-phase voltage UA、UB、UCWave-shape, zero-sequence current 3I0Waveform, zero sequence voltage 3U0Waveform, bus voltage UxThe waveform and the protection switching value TZ waveform. Meanwhile, in order to facilitate reading, time scales are marked on the transmission line fault recording graph and are displayed on two sides of the transmission line fault recording graph in a scale mode; wherein the time difference between each bin is 5 ms.
First, in fig. 2, in the transmission line C phase ICThe current waveform of the power transmission line with sudden change in the channel is in a bus C phase UCAnd if the channel has a sudden bus voltage waveform, the existence of the C-phase fault of the power transmission line is indicated. Meanwhile, 3I of zero sequence current waveform03U of channel and zero sequence voltage waveform0And if the channels all have waveform mutation, further explaining that the C-phase fault of the power transmission line is a C-phase grounding fault.
Secondly, in fig. 3, phase I is along the transmission line CCThe curve track of the distorted current waveform (such as a solid line) formed after the waveform in the channel is suddenly changed draws a sinusoidal waveform (such as a dotted line) with the same period and amplitude as the distorted current waveform, and finds a zero crossing point of the distorted current waveform and the sinusoidal waveform on any half-period wavelength. For example, at the first half-cycle wavelength, the zero-crossing d1 of the distorted current waveform and the zero-crossing d2 of the sinusoidal waveform; the zero-crossing d3 of the distorted current waveform and the zero-crossing d4 of the sinusoidal waveform at the first half-cycle wavelength, the zero-crossing d5 of the distorted current waveform and the zero-crossing d6 of the sinusoidal waveform at the first half-cycle wavelength, and so on.
Then, the time difference between the zero-crossing points of the distortion current waveform and the sine waveform at any half cycle wavelength is calculated, for example, m ═ d1-d2|, | d3-d4|, and | d5-d6|, and the differences are all equal, and the time difference is calculated from 5 ms/case.
And finally, judging whether the converted time difference is within a preset time difference range [4.3ms, 5ms ], if so, judging that the iron core of the current transformer has a saturation defect.
As shown in fig. 4, in an embodiment of the present invention, a system for determining saturation of a current transformer based on a power grid fault oscillogram includes:
the line fault oscillogram acquiring unit 110 is configured to acquire a transmission line fault oscillogram, where a transmission line three-phase current waveform, a bus three-phase voltage waveform, a zero-sequence current waveform, and a zero-sequence voltage waveform are formed on the transmission line fault oscillogram;
the power transmission line fault detection unit 120 is configured to determine that a power transmission line fault exists if the three-phase current waveform of the power transmission line and the three-phase voltage waveform of the bus have a waveform mutation;
a zero-crossing time difference calculation unit 130, configured to obtain a phase current waveform of any phase of the three-phase current waveform of the power transmission line after the transmission line fault is determined to exist, and a distortion current waveform correspondingly formed after any phase current waveform is suddenly changed, draw a sinusoidal waveform with a period and an amplitude equal to that of the distortion current waveform along a curve track of the distortion current waveform, and further determine a zero-crossing point where the distortion current waveform and the sinusoidal waveform are located at any half-period wavelength at the same time, so as to calculate a time difference between the zero-crossing point of the distortion current waveform and the zero-crossing point of the sinusoidal waveform;
and a saturation defect determining unit 140, configured to determine that a saturation defect exists in an iron core of the current transformer if the calculated time difference is within a preset time difference range.
Wherein the preset time difference range is [4.3ms, 5ms ].
Wherein, still include: a ground fault determination unit 150; wherein the content of the first and second substances,
and the ground fault determination unit is used for determining that the transmission line fault is a ground fault if the zero sequence current waveform and the zero sequence voltage waveform have waveform mutation when the transmission line fault is determined to exist.
Wherein, still include: inter-phase fault determination section 160; wherein the content of the first and second substances,
and the interphase fault determination unit is used for determining that the power transmission line fault is an interphase short-circuit fault if the zero-sequence current waveform and the zero-sequence voltage waveform do not have any waveform when the power transmission line fault is determined to exist, and at least two phase lines with sudden waveform changes in the three-phase current waveforms of the power transmission line are determined.
The embodiment of the invention has the following beneficial effects:
the invention detects whether the transmission line fault exists by identifying whether the transmission line current waveform with mutation exists in the transmission line three-phase current waveform and whether the bus three-phase voltage waveform with mutation exists in the bus three-phase voltage waveform in the transmission line fault oscillogram, and when the transmission line fault exists, by identifying the distorted current waveform formed by any phase current waveform in the three-phase current waveform of the power transmission line and drawing the sine waveform with the same period amplitude along the curve track of the distorted current waveform, comparing the time difference between the zero crossing points of the distorted current waveform and the sine waveform on any half-cycle wavelength at the same time, so as to determine whether the iron core of the current transformer has saturation defects, the whole process does not need excessive mathematical calculation, is simple and visual, and time-saving and labor-saving, and can solve the problem that field technicians cannot quickly judge the saturation phenomenon of the current transformer.
It should be noted that, in the above system embodiment, each included unit is only divided according to functional logic, but is not limited to the above division as long as the corresponding function can be implemented; in addition, specific names of the functional units are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present invention.
It will be understood by those skilled in the art that all or part of the steps in the method for implementing the above embodiments may be implemented by relevant hardware instructed by a program, and the program may be stored in a computer-readable storage medium, such as ROM/RAM, magnetic disk, optical disk, etc.
The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention, and it is therefore to be understood that the invention is not limited by the scope of the appended claims.
Claims (10)
1. A method for judging current transformer saturation based on a power grid fault oscillogram is characterized by comprising the following steps:
acquiring a transmission line fault recording diagram, wherein a transmission line three-phase current waveform, a bus three-phase voltage waveform, a zero-sequence current waveform and a zero-sequence voltage waveform are formed on the transmission line fault recording diagram;
if the three-phase current waveform of the power transmission line and the three-phase voltage waveform of the bus have waveform mutation, determining that the fault of the power transmission line exists;
after the transmission line fault is determined to exist, acquiring any phase current waveform mutation in the three-phase current waveform of the transmission line and a distortion current waveform correspondingly formed after the phase current waveform mutation, drawing a sine waveform with the same period and amplitude as the distortion current waveform along a curve track of the distortion current waveform, and further determining a zero crossing point of the distortion current waveform and the sine waveform on any half period wavelength simultaneously so as to calculate the time difference between the zero crossing point of the distortion current waveform and the zero crossing point of the sine waveform;
and if the calculated time difference is within the preset time difference range, judging that the iron core of the current transformer has a saturation defect.
2. The method for determining current transformer saturation based on grid fault oscillograms of claim 1, wherein the method further comprises:
and if the zero sequence current waveform and the zero sequence voltage waveform have waveform mutation when the transmission line fault is determined to exist, determining that the transmission line fault is a ground fault.
3. The method for determining current transformer saturation based on grid fault oscillograms of claim 2, wherein the method further comprises:
acquiring phase lines with waveform mutation in the three-phase current waveform of the power transmission line and the total number of corresponding statistics;
if the total number is one, the transmission line fault is determined to be a single-phase grounding fault, and the obtained phase line with the suddenly changed waveform is set as a fault phase line of the single-phase grounding fault;
if the total number is two, the transmission line fault is determined to be a two-phase interphase short circuit grounding fault, and the two phase lines with the sudden change of the acquired waveform are set as fault phase lines of the two-phase interphase short circuit grounding fault;
and if the total number is three, determining that the transmission line fault is a three-phase interphase short circuit grounding fault, and setting the three phase lines with the sudden change of the acquired waveforms as fault phase lines of the three-phase interphase short circuit grounding fault.
4. The method for determining current transformer saturation based on grid fault oscillograms of claim 1, wherein the method further comprises:
and if the zero-sequence current waveform and the zero-sequence voltage waveform do not have any waveform when the transmission line fault is determined to exist, determining that the transmission line fault is an interphase short-circuit fault, and at least two phase lines with sudden waveform changes in the three-phase current waveforms of the transmission line.
5. The method for determining current transformer saturation based on grid fault oscillograms of claim 4, wherein the method further comprises:
if the number of the phase lines with the sudden waveform changes in the three-phase current waveform of the power transmission line is two, the power transmission line fault is determined to be a two-phase interphase short-circuit fault, and the two phase lines with the sudden waveform changes are set as fault phase lines of the two-phase interphase short-circuit fault;
and if the three phase lines with the sudden change of the waveform in the three-phase current waveform of the power transmission line are three, determining that the fault of the power transmission line is a three-phase interphase short-circuit fault, and setting the three phase lines with the sudden change of the waveform as the fault phase lines with the three-phase interphase short-circuit fault.
6. The method for determining current transformer saturation based on grid fault oscillogram as claimed in claim 1, wherein the preset time difference range is [4.3ms, 5ms ].
7. A system for judging current transformer saturation based on a power grid fault oscillogram is characterized by comprising the following steps:
the device comprises a line fault oscillogram acquisition unit, a data acquisition unit and a data processing unit, wherein the line fault oscillogram acquisition unit is used for acquiring a transmission line fault oscillogram, and a transmission line three-phase current waveform, a bus three-phase voltage waveform, a zero-sequence current waveform and a zero-sequence voltage waveform are formed on the transmission line fault oscillogram;
the power transmission line fault detection unit is used for determining that a power transmission line fault exists if the three-phase current waveform of the power transmission line and the three-phase voltage waveform of the bus have waveform mutation;
the zero crossing point time difference calculation unit is used for acquiring any phase current waveform mutation in the three-phase current waveform of the power transmission line and a distortion current waveform correspondingly formed after the phase current waveform mutation after the power transmission line fault is determined to exist, drawing a sine waveform with the same period and amplitude as the distortion current waveform along a curve track of the distortion current waveform, and further determining the zero crossing point of the distortion current waveform and the sine waveform on any half period wavelength simultaneously so as to calculate the time difference between the zero crossing point of the distortion current waveform and the zero crossing point of the sine waveform;
and the saturation defect judging unit is used for judging that the iron core of the current transformer has the saturation defect if the calculated time difference is within the preset time difference range.
8. The system for determining current transformer saturation based on grid fault oscillograms according to claim 7, wherein said preset time difference range is [4.3ms, 5ms ].
9. The system for determining current transformer saturation based on grid fault oscillograms of claim 7, further comprising: a ground fault determination unit; wherein the content of the first and second substances,
and the ground fault determination unit is used for determining that the transmission line fault is a ground fault if the zero sequence current waveform and the zero sequence voltage waveform have waveform mutation when the transmission line fault is determined to exist.
10. The system for determining current transformer saturation based on grid fault oscillograms of claim 7, further comprising: an inter-phase fault determination unit; wherein the content of the first and second substances,
and the interphase fault determination unit is used for determining that the power transmission line fault is an interphase short-circuit fault if the zero-sequence current waveform and the zero-sequence voltage waveform do not have any waveform when the power transmission line fault is determined to exist, and at least two phase lines with sudden waveform changes in the three-phase current waveforms of the power transmission line are determined.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010604663.XA CN111751667B (en) | 2020-06-29 | 2020-06-29 | Method and system for judging current transformer saturation based on power grid fault recording diagram |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010604663.XA CN111751667B (en) | 2020-06-29 | 2020-06-29 | Method and system for judging current transformer saturation based on power grid fault recording diagram |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111751667A true CN111751667A (en) | 2020-10-09 |
| CN111751667B CN111751667B (en) | 2022-05-10 |
Family
ID=72677957
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010604663.XA Active CN111751667B (en) | 2020-06-29 | 2020-06-29 | Method and system for judging current transformer saturation based on power grid fault recording diagram |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111751667B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113064025A (en) * | 2021-03-26 | 2021-07-02 | 国家电网有限公司 | Ground fault line selection tripping method and system in resonance grounding system |
| CN115166585A (en) * | 2022-09-08 | 2022-10-11 | 石家庄科林电气股份有限公司 | Ground fault detection anti-misjudgment method and device and electronic equipment |
| CN117269700A (en) * | 2023-11-20 | 2023-12-22 | 国网江西省电力有限公司电力科学研究院 | Voltage transformer insulation defect diagnosis method based on fault wave recording information |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4217620A (en) * | 1978-02-06 | 1980-08-12 | Hydro-Quebec | Circuit for controlling induction in current transformers |
| EP0090095A1 (en) * | 1982-03-29 | 1983-10-05 | BBC Brown Boveri AG | Method and device for evaluating the secondary current of a current transformer primary connected to an electric power supply line |
| CN102928728A (en) * | 2012-10-30 | 2013-02-13 | 清华大学 | High-resistance grounding fault detection method based on zero-sequence current waveform distortion convexity and concavity |
| CN104466903A (en) * | 2014-11-26 | 2015-03-25 | 济南大学 | Current transformer saturation recognition method for differential protection |
| CN104682360A (en) * | 2015-01-22 | 2015-06-03 | 南京南瑞继保电气有限公司 | Method and device for identifying current transformer (TA) saturation |
| CN106842099A (en) * | 2017-04-10 | 2017-06-13 | 国家电网公司 | A kind of CT saturation recognition methods and device |
| CN111308406A (en) * | 2020-04-07 | 2020-06-19 | 国网江苏省电力有限公司电力科学研究院 | Current transformer saturation detection method, system, medium and electronic equipment |
-
2020
- 2020-06-29 CN CN202010604663.XA patent/CN111751667B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4217620A (en) * | 1978-02-06 | 1980-08-12 | Hydro-Quebec | Circuit for controlling induction in current transformers |
| EP0090095A1 (en) * | 1982-03-29 | 1983-10-05 | BBC Brown Boveri AG | Method and device for evaluating the secondary current of a current transformer primary connected to an electric power supply line |
| CN102928728A (en) * | 2012-10-30 | 2013-02-13 | 清华大学 | High-resistance grounding fault detection method based on zero-sequence current waveform distortion convexity and concavity |
| CN104466903A (en) * | 2014-11-26 | 2015-03-25 | 济南大学 | Current transformer saturation recognition method for differential protection |
| CN104682360A (en) * | 2015-01-22 | 2015-06-03 | 南京南瑞继保电气有限公司 | Method and device for identifying current transformer (TA) saturation |
| CN106842099A (en) * | 2017-04-10 | 2017-06-13 | 国家电网公司 | A kind of CT saturation recognition methods and device |
| CN111308406A (en) * | 2020-04-07 | 2020-06-19 | 国网江苏省电力有限公司电力科学研究院 | Current transformer saturation detection method, system, medium and electronic equipment |
Non-Patent Citations (8)
| Title |
|---|
| CHEN HONG: "A Scheme for Detection and Assessment of Current Transformer Saturation", 《2017 9TH INTERNATIONAL CONFERENCE ON MEASURING TECHNOLOGY AND MECHATRONICS AUTOMATION (ICMTMA)》 * |
| E. M. DOS SANTOS: "CT Saturation Detection Based on the Distance Between Consecutive Points in the Plans Formed by the Secondary Current Samples and Their Difference-Functions", 《 IEEE TRANSACTIONS ON POWER DELIVERY》 * |
| SAVAGE3232: "保护动作报告及故障录波图的识别", 《百度文库，HTTPS://WENKU.BAIDU.COM/VIEW/13CC0A79680203D8CF2F241E.HTML》 * |
| 任力: "一种基于Hausdorff距离算法的电流互感器饱和识别策略", 《湖北电力》 * |
| 李岩: "鉴别TA饱和的改进时差法研究", 《水利电力科技》 * |
| 李鼎盛: "根据故障录波图的波形参数寻找线路故障点", 《继电器》 * |
| 程利军: "基于采样值的CT饱和检测方案的研究", 《继电器》 * |
| 董新涛: "基于动态虚拟磁通分析的CT饱和识别方案研究", 《电力系统保护与控制》 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113064025A (en) * | 2021-03-26 | 2021-07-02 | 国家电网有限公司 | Ground fault line selection tripping method and system in resonance grounding system |
| CN113064025B (en) * | 2021-03-26 | 2022-06-21 | 国家电网有限公司 | Ground fault line selection tripping method and system in resonance grounding system |
| CN115166585A (en) * | 2022-09-08 | 2022-10-11 | 石家庄科林电气股份有限公司 | Ground fault detection anti-misjudgment method and device and electronic equipment |
| CN115166585B (en) * | 2022-09-08 | 2022-11-29 | 石家庄科林电气股份有限公司 | Ground fault detection anti-misjudgment method and device and electronic equipment |
| CN117269700A (en) * | 2023-11-20 | 2023-12-22 | 国网江西省电力有限公司电力科学研究院 | Voltage transformer insulation defect diagnosis method based on fault wave recording information |
| CN117269700B (en) * | 2023-11-20 | 2024-03-12 | 国网江西省电力有限公司电力科学研究院 | Voltage transformer insulation defect diagnosis method based on fault wave recording information |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111751667B (en) | 2022-05-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111751667B (en) | Method and system for judging current transformer saturation based on power grid fault recording diagram | |
| CN109061384A (en) | A kind of one-phase earthing failure in electric distribution network phase discrimination method and system | |
| CN111751664A (en) | Method and system for judging grounding faults in positive and negative directions in protection based on power grid oscillogram | |
| Espin-Delgado et al. | Characterization of phase-angle jump in radial systems using incremental voltage phasors | |
| CN115267640A (en) | Current transformer abnormity checking method, system, equipment and medium | |
| CN113109671B (en) | Method for accelerating detection of small half-wave stage of fault current | |
| CN111751661A (en) | Method and system for judging ground fault based on power grid fault recording diagram | |
| CN112147396A (en) | Method and system for calculating percentage of direct current component of short-circuit current | |
| CN111751660A (en) | Method and system for judging inter-phase faults in forward and reverse directions in protection based on power grid oscillogram | |
| CN110716168A (en) | Method for detecting performance of traveling wave distance measuring device | |
| CN108152583B (en) | Method and device for separating fundamental wave and harmonic component of leakage current | |
| Saha et al. | A new adaptive high speed distance protection scheme for power transmission lines | |
| Li et al. | Study on sequence component based fault phase selector during power swings | |
| Fazio et al. | Comparative analysis for reactive energy measurement methodologies, under non-sinusoidal conditions in three-phase four-wire circuits | |
| CN111751665A (en) | Method and system for judging phase-to-phase fault based on power grid fault recording graph | |
| CN112578228A (en) | Zero-sequence-independent single-phase earth fault discrimination algorithm for power distribution network | |
| CN111751659B (en) | Zero-phase current wiring method and system for judging wave recorder based on power grid fault wave recording diagram | |
| CN111751666B (en) | Method and system for judging successive faults based on power grid fault recording graph | |
| CN110244167A (en) | The detection method of three-phase inverter short trouble | |
| CN111610469B (en) | Three-phase synchronous frequency response detection method and system for star transformer winding deformation | |
| CN114594345A (en) | Method and device for identifying phase of low-voltage power grid leakage fault | |
| Popescu et al. | Design and evaluation of a single-phase directional overcurrent protection relay implemented using a raspberry PI | |
| CN111751662A (en) | Method and system for judging charging protection action reason of electrical equipment based on oscillogram | |
| RU57018U1 (en) | DEVICE FOR DETERMINING THE LOCATION OF DAMAGE TO THE ELECTRICAL VOLTAGE NETWORK OF 6 (10) -35 KV WITH ISOLATED OR COMPENSATED NEUTRAL | |
| Leborgne et al. | Using pq-monitor and PMU for voltage sag extended-characterization |
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 |