CN111751670A - Method and system for judging internal and external faults of main transformer area based on power grid fault recording graph - Google Patents
Method and system for judging internal and external faults of main transformer area based on power grid fault recording graph Download PDFInfo
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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
- G01R31/08—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
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- 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
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- 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
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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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- 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
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- 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
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Abstract
The invention provides a method for judging faults inside and outside a main transformer area based on a power grid fault recording diagram, which comprises the steps of obtaining a main transformer fault recording diagram, wherein a protection switching value waveform, a trip switching value waveform, a main transformer high-voltage side three-phase current and voltage waveform, and a main transformer low-voltage side three-phase current and voltage waveform are formed on the main transformer fault recording diagram; if the three-phase current waveforms on the high and low voltage sides of the main transformer have mutation and the three-phase voltage waveforms on the high and low side of the main transformer have mutation, the main transformer fault is determined to exist; when the main transformer fault exists, the current waveforms of all phase currents which are mutated and the current waveforms before the respective corresponding mutations are obtained from the three-phase current waveforms of the high-low voltage side of the main transformer, and the main transformer fault is judged to be an internal fault or an external fault according to the phase direction changes of the current waveforms of all phase currents which are mutated in the three-phase current waveforms of the high-low voltage side of the main transformer and the current waveforms before the respective corresponding mutations. The implementation of the invention overcomes the defects of the prior art, does not need mathematical calculation, is simple and intuitive, and saves time and labor.
Description
Technical Field
The invention relates to the technical field of relay protection, in particular to a method and a system for judging internal and external faults of a main transformer area based on a power grid fault recording graph.
Background
The main transformer is one of the important components of a power plant and a transformer substation in a power grid system, plays a role in power grid communication of different voltage levels, and is important equipment for high-voltage transmission of electric energy and voltage communication of different voltage levels. The main transformer comprises a main transformer sleeve, an outgoing line, a current transformer, a coil, an iron core and other elements, main transformer windings of different voltage levels are wound on the same iron core, and thus a plurality of elements are insulated by means of transformer oil. Due to a plurality of elements, the damage of the internal elements of the main transformer caused by insulation aging, transformer oil aging, direct insulation damage of windings, lightning stroke and other external short circuits is difficult to avoid.
The main transformer has various fault types, such as a single-phase earth fault of a sleeve, a turn-to-turn short circuit fault of a winding of the main transformer, a two-phase interphase short circuit fault of the winding, a short circuit fault caused by the oil level drop of the main transformer and the like. If the faults in or out of the main transformer area cannot be accurately judged, the power transmission is recovered blindly before the fault point is eliminated, so that the faults can occur again, even the transformer is damaged, and the stability of the system is damaged, so that the main transformer is scrapped or the total station blackout and the full power system are collapsed. Therefore, it is particularly important to accurately determine whether an intra-zone or an extra-zone fault has occurred.
In order to meet the requirements of rapidity and selectivity, the main transformer protection is formed according to a differential principle, so that a technician can judge whether a fault exists in the main transformer differential protection based on the kirchhoff current law, namely judge whether the fault exists by calculating the sum of currents on each side. For example, when a fault occurs in the main transformer area, fault currents are supplied to a fault point on both the high-voltage side and the low-voltage side of the main transformer, and the difference current of the main transformer protection can be calculated and obtained as the sum of the currents on each side. For another example, when the main transformer has an external fault, the fault current on the high-voltage side of the main transformer flows to the fault point on the low-voltage side through the main transformer body, and the differential current of the main transformer protection can be calculated to be 0.
However, the above-mentioned determination method involves reading, calculating, etc. the magnitude and direction of each phase current on each side of the main transformer, resulting in being error-prone, unintuitive, time-consuming and laborious.
In order to overcome the defects and shortcomings in the prior art, the inventor provides a method for judging the internal and external faults of a main transformer area based on a power grid fault recording graph, 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 faults inside and outside a main transformer area based on a power grid fault recording graph, which can overcome the defects and shortcomings of the prior art, does not need mathematical calculation, is simple and intuitive, and is time-saving and labor-saving.
In order to solve the above technical problem, an embodiment of the present invention provides a method for determining an internal fault and an external fault of a main transformer area based on a power grid fault oscillogram, where the method includes the following steps:
step S1, obtaining a main transformer fault recording diagram, wherein a protection switching value waveform, a trip switching value waveform, a main transformer high-voltage side three-phase current waveform, a main transformer high-voltage side three-phase voltage waveform, a main transformer low-voltage side three-phase current waveform and a main transformer low-voltage side three-phase voltage waveform are formed on the main transformer fault recording diagram;
step S2, if the high-voltage side three-phase current waveform and the low-voltage side three-phase current waveform of the main transformer both have abrupt current waveforms, and the high-voltage side three-phase voltage waveform and the low-voltage side three-phase voltage waveform of the main transformer both have abrupt voltage waveforms, the main transformer fault is determined to exist;
and step S3, after the main transformer fault is determined to exist, obtaining the current waveforms of each phase which is mutated and the current waveforms before the respective corresponding mutation in the three-phase current waveforms at the high-voltage side of the main transformer and the three-phase current waveforms at the low-voltage side of the main transformer, and judging the main transformer fault to be an internal fault or an external fault according to the phase direction changes of the current waveforms of each phase which is mutated and the current waveforms before the respective corresponding mutation in the three-phase current waveforms at the high-voltage side of the main transformer and the three-phase current waveforms at the low-voltage side of the main transformer.
Wherein, the step S3 specifically includes:
acquiring current waveforms of each phase with sudden change and current waveforms before respective corresponding sudden change in the three-phase current waveforms of the high-voltage side of the main transformer, and acquiring current waveforms of each phase with sudden change and current waveforms before respective corresponding sudden change in the three-phase current waveforms of the low-voltage side of the main transformer;
taking out phase lines of current waveforms with mutation in the same phase from the high-voltage side three-phase current waveforms and the low-voltage side three-phase current waveforms of the main transformer;
if the phase direction of the current waveform mutated on the current phase line obtained in the high-voltage side three-phase current waveform of the main transformer is not changed compared with the phase direction of the current waveform mutated before the mutation, and the phase direction of the current waveform mutated on the current phase line obtained in the low-voltage side three-phase current waveform of the main transformer is changed compared with the phase direction of the current waveform mutated before the mutation, the main transformer fault is judged to be an in-zone fault;
and if the phase direction of the current waveform mutated on the current phase line obtained in the high-voltage side three-phase current waveform of the main transformer compared with the current waveform mutated before the mutation is not changed, and the phase direction of the current waveform mutated on the current phase line obtained in the low-voltage side three-phase current waveform of the main transformer compared with the current waveform mutated before the mutation is not changed, judging that the main transformer fault is an external fault.
Wherein the method further comprises:
setting a region where the waveform of the protection switching value has mutation as a first mutation region, and setting a region where the waveform of the trip switching value has mutation as a second mutation region; wherein the second mutated region is located within the first mutated region;
when the main transformer fault is an in-zone fault, if the current waveforms of all phases which are mutated in the main transformer high-voltage side three-phase current waveform and the main transformer high-voltage side three-phase current waveform are both located in the second mutation zone, the protection action of the in-zone fault is determined to be correct;
and when the main transformer fault is an external fault, if the current waveforms of the currents of the high-voltage side three-phase current of the main transformer and the currents of the various phases which are mutated in the three-phase current waveform of the high-voltage side of the main transformer are both located in the first mutation region, determining the protection misoperation of the external fault.
Wherein the method further comprises:
and identifying the phase line with the sudden change of the same-phase current waveform as the phase line with the fault in the main transformer fault.
The embodiment of the invention also provides a system for judging the internal and external faults of the main transformer area based on the power grid fault recording chart, which comprises the following steps:
the main transformer fault recording diagram acquisition unit is used for acquiring a main transformer fault recording diagram, and a protection switching value waveform, a trip switching value waveform, a main transformer high-voltage side three-phase current waveform, a main transformer high-voltage side three-phase voltage waveform, a main transformer low-voltage side three-phase current waveform and a main transformer low-voltage side three-phase voltage waveform are formed on the main transformer fault recording diagram;
the main transformer fault detection unit is used for determining that a main transformer fault exists if sudden change current waveforms exist in the high-voltage side three-phase current waveform and the low-voltage side three-phase current waveform of the main transformer;
and the main transformer fault determination unit is used for acquiring the current waveforms of all phases which are mutated and the current waveforms before the respective corresponding mutations in the three-phase current waveforms at the high-voltage side of the main transformer and the three-phase current waveforms at the low-voltage side of the main transformer after the main transformer fault is determined to exist, and determining that the main transformer fault is an in-zone fault or an out-zone fault according to the phase direction changes of the current waveforms of all phases which are mutated in the three-phase current waveforms at the high-voltage side of the main transformer and the three-phase current waveforms at the low-voltage side of the main transformer and the current waveforms.
Wherein the main transformer fault determination unit includes:
the current waveform acquisition module is used for acquiring current waveforms of all phases which are mutated and current waveforms before respective corresponding mutation in the three-phase current waveforms of the high-voltage side of the main transformer, and acquiring the current waveforms of all phases which are mutated and the current waveforms before respective corresponding mutation in the three-phase current waveforms of the low-voltage side of the main transformer;
the selection module is used for taking out phase lines of current waveforms with sudden changes in the same phase from the three-phase current waveforms on the high-voltage side of the main transformer and the three-phase current waveforms on the low-voltage side of the main transformer;
the first judging module is used for judging that the main transformer fault is an in-region fault if the phase direction of the current waveform with mutation on the current phase line obtained in the main transformer high-voltage side three-phase current waveform is not changed compared with the phase direction of the current waveform with mutation before the mutation, and the phase direction of the current waveform with mutation on the current phase line obtained in the main transformer low-voltage side three-phase current waveform is changed compared with the phase direction of the current waveform with mutation before the mutation;
and the second judging module is used for judging that the main transformer fault is an external fault if the phase direction of the current waveform mutated on the current phase line obtained in the main transformer high-voltage side three-phase current waveform compared with the current waveform mutated before mutation is not changed, and the phase direction of the current waveform mutated on the current phase line obtained in the main transformer low-voltage side three-phase current waveform compared with the current waveform mutated on the current phase line obtained in the main transformer low-voltage side three-phase current waveform is not changed.
Wherein, the main transformer fault determination unit further comprises:
the sudden change region setting module is used for setting a region where the waveform of the protection switching value has sudden change as a first sudden change region and setting a region where the waveform of the trip switching value has sudden change as a second sudden change region; wherein the second mutated region is located within the first mutated region;
the first identification module is used for determining that the protection action of the fault in the area is correct if the main transformer high-voltage side three-phase current waveform and the current waveforms of all phases which are mutated in the main transformer high-voltage side three-phase current waveform are both located in the second mutation area when the main transformer fault is the fault in the area;
and the second identification module is used for identifying the protection misoperation of the external fault if the main transformer high-voltage side three-phase current waveform and the current waveforms of all phases which are mutated in the main transformer high-voltage side three-phase current waveform are both positioned in the first mutation region when the main transformer fault is the external fault.
Wherein, the main transformer fault determination unit further comprises:
and the fault phase line identification module is used for identifying the phase line with the sudden change of the same-phase current waveform as the phase line with the fault in the main transformer fault.
The embodiment of the invention has the following beneficial effects:
the method detects whether the main transformer fault exists by identifying whether the current waveform of the sudden change exists in the three-phase current waveform of the high-low voltage side of the main transformer and the voltage waveform of the sudden change exists in the three-phase voltage waveform of the high-low voltage side of the main transformer in the main transformer fault recording chart, and visually determines whether the main transformer fault is an internal fault or an external fault by identifying the sudden change of each phase current in the three phases of the high-voltage side of the main transformer and the phase direction change of the waveform before the sudden change, and the sudden change of each phase current in the three phases of the low-voltage side of the main transformer and the phase direction change of the waveform before the sudden change when the main transformer fault exists.
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 internal and external faults of a main transformer area based on a power grid fault oscillogram according to an embodiment of the present invention;
fig. 2 is a main transformer fault recording diagram when a main transformer has an intra-area fault in an application scenario of the method for determining the intra-area and the extra-area faults of the main transformer based on the power grid fault recording diagram according to the embodiment of the present invention;
fig. 3 is a main transformer fault recording diagram when a main transformer has an external fault in an application scenario of the method for determining the internal and external faults of the main transformer based on the power grid fault recording diagram according to the embodiment of the present invention;
fig. 4 is a schematic structural diagram for determining internal and external faults of a main transformer area 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.
The inventor finds that the phases of the current wave diagrams of the high-voltage side and the low-voltage side of the main transformer can be changed when the main transformer area has an internal fault, and the phases of the current wave diagrams of the high-voltage side and the low-voltage side of the main transformer can not be changed when the main transformer area has an external fault. Therefore, as shown in fig. 1, in the embodiment of the present invention, the inventor provides a method for determining faults inside and outside a main transformer area based on a grid fault oscillogram, where the method includes the following steps:
step S1, obtaining a main transformer fault recording diagram, wherein a protection switching value waveform, a trip switching value waveform, a main transformer high-voltage side three-phase current waveform, a main transformer high-voltage side three-phase voltage waveform, a main transformer low-voltage side three-phase current waveform and a main transformer low-voltage side three-phase voltage waveform are formed on the main transformer fault recording diagram;
step S2, if the high-voltage side three-phase current waveform and the low-voltage side three-phase current waveform of the main transformer both have abrupt current waveforms, and the high-voltage side three-phase voltage waveform and the low-voltage side three-phase voltage waveform of the main transformer both have abrupt voltage waveforms, the main transformer fault is determined to exist;
and step S3, after the main transformer fault is determined to exist, obtaining the current waveforms of each phase which is mutated and the current waveforms before the respective corresponding mutation in the three-phase current waveforms at the high-voltage side of the main transformer and the three-phase current waveforms at the low-voltage side of the main transformer, and judging the main transformer fault to be an internal fault or an external fault according to the phase direction changes of the current waveforms of each phase which is mutated and the current waveforms before the respective corresponding mutation in the three-phase current waveforms at the high-voltage side of the main transformer and the three-phase current waveforms at the low-voltage side of the main transformer.
In step S1, acquiring a main transformer fault recording diagram through a wave recorder and importing the main transformer fault recording diagram into computer equipment, so that the computer equipment can call various main transformer fault recording diagrams at any time; the main transformer fault recording diagram includes, but is not limited to, a protection switching value waveform, a trip switching value waveform, a main transformer high-voltage side three-phase current waveform, a main transformer high-voltage side three-phase voltage waveform, a main transformer low-voltage side three-phase current waveform, a main transformer low-voltage side three-phase voltage waveform, and the like, and if a three-phase differential protection current waveform is formed.
In step S2, determining whether there is a sudden change in the waveform of each phase of current according to the amplitude change in the waveform of each phase of current in the waveform of the main transformer high-voltage side three-phase current and the waveform of each phase of current in the waveform of the main transformer low-voltage side three-phase current, and determining whether there is a sudden change in the waveform of each phase of voltage according to the amplitude change in the waveform of each phase of voltage in the waveform of each phase of; 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; if the amplitude of a certain phase voltage waveform suddenly decreases within a certain period of time, namely the position of a peak or a trough on a voltage curve lags behind the peak or the trough of the original curve, the phase voltage waveform is determined to have sudden change;
if the same phase or multi-phase current waveforms exist in the main transformer high-voltage side three-phase current waveforms and the main transformer low-voltage side three-phase current waveforms (such as sudden increase), and the same phase or multi-phase voltage waveforms exist in the main transformer high-voltage side three-phase voltage waveforms and the main transformer low-voltage side three-phase voltage waveforms (such as sudden decrease), the main transformer fault is determined to exist. If the same-phase (such as A-phase) current waveform in the main transformer high-voltage side three-phase current waveform and the main transformer low-voltage side three-phase current waveform is increased suddenly and the same-phase (such as A-phase) voltage waveform in the corresponding main transformer high-voltage side three-phase voltage waveform and the corresponding main transformer low-voltage side three-phase voltage waveform is reduced suddenly, the main transformer fault is determined to exist.
In step S3, the computer device identifies various waveforms on the main transformer fault oscillogram, and can visually determine whether the main transformer fault is an intra-area fault or an extra-area fault according to the identified various waveforms, and the whole process is simple and intuitive without mathematical calculation, and is time-saving and labor-saving. It can be understood that the main transformer fault recording chart can be directly identified through manpower or naked eyes, the main transformer fault is visually judged to be an internal fault or an external fault, the whole process does not need mathematical calculation, and the method is simple, visual and time-saving and labor-saving.
The specific process for visually judging whether the main transformer fault is an intra-area fault or an extra-area fault is as follows:
firstly, obtaining the current waveforms of each phase with sudden change and the current waveforms before the respective corresponding sudden change in the three-phase current waveforms at the high-voltage side of the main transformer, and obtaining the current waveforms of each phase with sudden change and the current waveforms before the respective corresponding sudden change in the three-phase current waveforms at the low-voltage side of the main transformer.
And secondly, taking out phase lines of current waveforms with sudden changes in the same phase from the three-phase current waveforms on the high-voltage side of the main transformer and the three-phase current waveforms on the low-voltage side of the main transformer. It can be understood that the phase line (which may be a single phase line or multiple phase lines) with abrupt changes in the same-phase current waveforms is regarded as the phase line with the fault in the main transformer fault; for example, if the phase current of the phase a in the high-voltage side three-phase current waveform and the low-voltage side three-phase current waveform of the main transformer have sudden changes, the phase line with the fault is the phase a.
And finally, if the phase direction of the current waveform mutated on the current phase line obtained in the high-voltage side three-phase current waveform of the main transformer is not changed compared with the phase direction of the current waveform mutated before the mutation, and the phase direction of the current waveform mutated on the current phase line obtained in the low-voltage side three-phase current waveform of the main transformer is changed compared with the phase direction of the current waveform mutated before the mutation, the main transformer fault is judged to be an in-zone fault. Namely, the amplitude of the waveform is changed before and after the current phase line current mutation in the main transformer high-voltage side three-phase current waveform, but the amplitude of the waveform is changed before and after the current phase line current mutation in the main transformer low-voltage side three-phase current waveform and the phase direction of the waveform is also changed (such as a trend of 180 degrees in a reverse direction); or
And if the phase direction of the current waveform on the current phase line obtained from the high-voltage side three-phase current waveform of the main transformer is not changed compared with the phase direction of the current waveform before mutation, and the phase direction of the current waveform on the current phase line obtained from the low-voltage side three-phase current waveform of the main transformer is not changed compared with the phase direction of the current waveform before mutation, the main transformer fault is judged to be an external fault. Namely, the amplitude of the waveform is changed before and after the current mutation of the phase line in the main transformer high-voltage side three-phase current waveform and the main transformer low-voltage side three-phase current waveform.
In the embodiment of the invention, whether the protection action is correct or not can be compared based on the region where the protection switching value waveform and the trip switching value waveform have sudden change. Accordingly, the method further comprises:
setting a region where the waveform of the protection switching value has mutation as a first mutation region, and setting a region where the waveform of the trip switching value has mutation as a second mutation region; wherein the second mutation region is positioned in the first mutation region, and the tripping operation belongs to one action of protection;
when the main transformer fault is an internal fault, if the main transformer high-voltage side three-phase current waveform and each phase current waveform mutated in the main transformer high-voltage side three-phase current waveform are both located in a second mutation region, the protection action of the internal fault is determined to be correct;
when the main transformer fault is an external fault, if the main transformer high-voltage side three-phase current waveform and the current waveforms of the various phases which are suddenly changed in the main transformer high-voltage side three-phase current waveform are both positioned in the first sudden change region, the protection misoperation of the external fault is determined, namely the sudden change current waveforms are led out in advance due to the protection misoperation.
As shown in fig. 2 and fig. 3, an application scenario of the method for determining internal and external faults of a main transformer area based on a power grid fault recording diagram according to the embodiment of the present invention is further described:
the main transformer fault recording diagram comprises a protection switching value QD waveform, a tripping switching value TZ waveform, main transformer high-voltage side three-phase currents IHa, IHb and IHc waveforms, main transformer low-voltage side three-phase currents IMa, IMb and IMc waveforms, main transformer high-voltage side three-phase voltages UHa, UHb and UHc waveforms, main transformer low-voltage side three-phase voltages UMa, UMb and UMc waveforms and three-phase differential protection currents IDa, IDb and IDc waveforms.
The QD waveform has a sudden change (as shown by the black bold line in the figure, the length is the first sudden change region), i.e. the protection start has a switch-out; the trip switching value TZ waveform has a sudden change (such as a black bold line, the length is a second sudden change region), namely, the trip switching value TZ waveform is opened for the trip action; and finally, the waveform of the protection switching value QD and the waveform of the trip switching value TZ disappear, and the trip breaking current flows to a fault point.
In fig. 2, there is a sudden change in the current waveform in the main transformer high-voltage side a-phase IHa channel, and the phase direction of the sudden change in the current waveform and the current waveform before the sudden change is not changed, and there is also a sudden change in the current waveform in the main transformer low-voltage side a-phase IMa channel, but the phase direction of the sudden change in the current waveform and the current waveform before the sudden change is changed (for example, 180 degrees in the opposite direction), so that it can be determined that the main transformer fault is an intra-zone fault, that is, the main transformer fault is an intra-a-phase zone fault, the main transformer high-voltage side and the main transformer low-voltage side a-phase currents both have sudden changes in the main transformer protection operation, and when the sudden change occurs, the phase direction of the main transformer high-voltage side a-phase current waveform is not changed, and the phase direction of the main transformer low. It should be noted that the abrupt current in the phase a channel disappears completely after a duration of 43ms (two cycles and multipoint, 20ms per cycle), and the unchanged size and direction in the phase B, C channel also disappear simultaneously in the phase a, because the protection operation jumps to the middle three-phase switch after the fault.
At this time, it is determined that the QD waveform has a sudden change before the occurrence of the fault for 60ms, such as the occurrence of a first sudden change region indicated by a black bold line, and that the TZ waveform of the trip switching value has a sudden change after the occurrence of the fault for 4-5ms, such as the occurrence of a second sudden change region indicated by a black bold line. And since the abrupt current in the channel of the A phase IHa at the high-voltage side of the main transformer is located in the second abrupt change region, and the abrupt current in the channel of the A phase IMa at the low-voltage side of the main transformer is also located in the second abrupt change region, the fault protection action in the region is determined to be correct.
In fig. 3, when there is a sudden change in the current waveform in the passage of the main transformer high-voltage side a-phase IHa, and the direction of the phase of the sudden change in the current waveform and the direction of the phase of the current waveform before the sudden change are not changed, and there is a sudden change in the current waveform in the passage of the main transformer low-voltage side a-phase IMa, and the direction of the phase of the sudden change in the current waveform and the direction of the phase of the current waveform before the sudden change are not changed, it can be determined from the above characteristics that the main transformer fault is an out-of-range fault, that is, the a-phase out-of-range fault occurs in the main transformer fault, and the a-phase currents on the main transformer high-voltage side and the main transformer low-voltage side both have sudden changes, and when the sudden change occurs, the phase direction of the main transformer high. It should be noted that the abrupt current in the phase a channel disappears completely after a duration of 90ms (lasting four half cycles and multipoint, 20ms per cycle), and the unchanged size and direction in the phase B, C channel also disappear simultaneously in the phase a, because the protection operation jumps to the middle three-phase switch after the fault.
At this time, it is determined that the protection switching value QD waveform has an abrupt change at the occurrence of a fault, such as the occurrence of a first abrupt change region indicated by a black bold line, and that the trip switching value TZ waveform has an abrupt change after the occurrence of a fault for 35ms (for one half cycle multiple point, 20ms per cycle), such as the occurrence of a second abrupt change region indicated by a black bold line. The sudden change current in the main transformer high-voltage side A-phase IHa channel is located in a first sudden change region, and meanwhile, the sudden change current in the main transformer low-voltage side A-phase IMa channel is also located in the first sudden change region, so that the fault protection misoperation outside the main transformer region is determined, namely, a sudden change current waveform is led out in advance due to the protection misoperation.
As shown in fig. 4, in an embodiment of the present invention, a system for determining internal and external faults of a main transformer area based on a power grid fault oscillogram includes:
the main transformer fault recording diagram acquiring unit 110 is used for acquiring a main transformer fault recording diagram, and a protection switching value waveform, a trip switching value waveform, a main transformer high-voltage side three-phase current waveform, a main transformer high-voltage side three-phase voltage waveform, a main transformer low-voltage side three-phase current waveform and a main transformer low-voltage side three-phase voltage waveform are formed on the main transformer fault recording diagram;
the main transformer fault detection unit 120 is configured to determine that a main transformer fault exists if a current waveform with a sudden change exists in the main transformer high-voltage side three-phase current waveform and the main transformer low-voltage side three-phase current waveform, and a voltage waveform with a sudden change exists in the main transformer high-voltage side three-phase voltage waveform and the main transformer low-voltage side three-phase voltage waveform;
the main transformer fault determination unit 130 is configured to acquire, after the main transformer fault is determined to exist, each phase current waveform that is mutated and a current waveform before each corresponding mutation in each of the main transformer high-voltage side three-phase current waveform and the main transformer low-voltage side three-phase current waveform, and determine that the main transformer fault is an intra-area fault or an extra-area fault according to a phase direction change of each phase current waveform that is mutated and a current waveform before each corresponding mutation in each of the main transformer high-voltage side three-phase current waveform and the main transformer low-voltage side three-phase current waveform.
Wherein the master fault determination unit 130 includes:
a current waveform obtaining module 1301, configured to obtain, in the main transformer high-voltage side three-phase current waveform, an abrupt change of each phase current waveform and a current waveform before respective corresponding abrupt change, and obtain, in the main transformer low-voltage side three-phase current waveform, an abrupt change of each phase current waveform and a current waveform before respective corresponding abrupt change;
a selecting module 1302, configured to extract phase lines of current waveforms having abrupt changes in the same phase from the high-voltage side three-phase current waveform and the low-voltage side three-phase current waveform of the main transformer;
the first judging module 1303 is configured to judge that the main transformer fault is an in-region fault if the phase direction of a current waveform, which is suddenly changed on a current phase line of the main transformer high-voltage side three-phase current waveform and is compared with the phase direction of a current waveform, which is not suddenly changed, of the current waveform, which is suddenly changed on the current phase line of the main transformer low-voltage side three-phase current waveform and is compared with the phase direction of the current waveform, which is suddenly changed, of the current phase line of the main transformer high-voltage side three-phase current waveform are not changed;
a second determination module 1304, configured to determine that the main transformer fault is an external fault if the phase direction of the current waveform mutated on the current phase line obtained in the main transformer high-voltage side three-phase current waveform compared with the current waveform mutated before mutation is not changed, and the phase direction of the current waveform mutated on the current phase line obtained in the main transformer low-voltage side three-phase current waveform compared with the current waveform mutated on the current phase line obtained in the main transformer low-voltage side three-phase current waveform is not changed.
Wherein, the main transformer fault determination unit 130 further includes:
a sudden change region setting module 1305, configured to set a region where the protection switching value waveform has a sudden change as a first sudden change region, and a region where the trip switching value waveform has a sudden change as a second sudden change region; wherein the second mutated region is located within the first mutated region;
the first identification module 1306 is configured to, when the main transformer fault is an intra-area fault, determine that a protection action of the intra-area fault is correct if the main transformer high-voltage side three-phase current waveform and each phase current waveform that is suddenly changed in the main transformer high-voltage side three-phase current waveform are both located in the second sudden change area;
the second identification module 1307 is configured to, when the main transformer fault is an external fault, determine that protection malfunction of the external fault occurs if the main transformer high-voltage side three-phase current waveform and each phase current waveform mutated in the main transformer high-voltage side three-phase current waveform are both located in the first mutation region.
Wherein, the main transformer fault determination unit 130 further includes:
and a faulty phase line identification module 1308, configured to identify a phase line with a sudden change in the obtained in-phase current waveforms as a phase line with a fault in the main transformer fault.
The embodiment of the invention has the following beneficial effects:
the method detects whether the main transformer fault exists by identifying whether the current waveform of the sudden change exists in the three-phase current waveform of the high-low voltage side of the main transformer and the voltage waveform of the sudden change exists in the three-phase voltage waveform of the high-low voltage side of the main transformer in the main transformer fault recording chart, and visually determines whether the main transformer fault is an internal fault or an external fault by identifying the sudden change of each phase current in the three phases of the high-voltage side of the main transformer and the phase direction change of the waveform before the sudden change, and the sudden change of each phase current in the three phases of the low-voltage side of the main transformer and the phase direction change of the waveform before the sudden change when the main transformer fault exists.
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 (8)
1. A method for judging the internal and external faults of a main transformer area based on a power grid fault recording graph is characterized by comprising the following steps:
step S1, obtaining a main transformer fault recording diagram, wherein a protection switching value waveform, a trip switching value waveform, a main transformer high-voltage side three-phase current waveform, a main transformer high-voltage side three-phase voltage waveform, a main transformer low-voltage side three-phase current waveform and a main transformer low-voltage side three-phase voltage waveform are formed on the main transformer fault recording diagram;
step S2, if the high-voltage side three-phase current waveform and the low-voltage side three-phase current waveform of the main transformer both have abrupt current waveforms, and the high-voltage side three-phase voltage waveform and the low-voltage side three-phase voltage waveform of the main transformer both have abrupt voltage waveforms, the main transformer fault is determined to exist;
and step S3, after the main transformer fault is determined to exist, obtaining the current waveforms of each phase which is mutated and the current waveforms before the respective corresponding mutation in the three-phase current waveforms at the high-voltage side of the main transformer and the three-phase current waveforms at the low-voltage side of the main transformer, and judging the main transformer fault to be an internal fault or an external fault according to the phase direction changes of the current waveforms of each phase which is mutated and the current waveforms before the respective corresponding mutation in the three-phase current waveforms at the high-voltage side of the main transformer and the three-phase current waveforms at the low-voltage side of the main transformer.
2. The method for judging the internal and external faults of the main transformer area based on the grid fault oscillogram as claimed in claim 1, wherein the step S3 specifically includes:
acquiring current waveforms of each phase with sudden change and current waveforms before respective corresponding sudden change in the three-phase current waveforms of the high-voltage side of the main transformer, and acquiring current waveforms of each phase with sudden change and current waveforms before respective corresponding sudden change in the three-phase current waveforms of the low-voltage side of the main transformer;
taking out phase lines of current waveforms with mutation in the same phase from the high-voltage side three-phase current waveforms and the low-voltage side three-phase current waveforms of the main transformer;
if the phase direction of the current waveform mutated on the current phase line obtained in the high-voltage side three-phase current waveform of the main transformer is not changed compared with the phase direction of the current waveform mutated before the mutation, and the phase direction of the current waveform mutated on the current phase line obtained in the low-voltage side three-phase current waveform of the main transformer is changed compared with the phase direction of the current waveform mutated before the mutation, the main transformer fault is judged to be an in-zone fault;
and if the phase direction of the current waveform mutated on the current phase line obtained in the high-voltage side three-phase current waveform of the main transformer compared with the current waveform mutated before the mutation is not changed, and the phase direction of the current waveform mutated on the current phase line obtained in the low-voltage side three-phase current waveform of the main transformer compared with the current waveform mutated before the mutation is not changed, judging that the main transformer fault is an external fault.
3. The method for determining faults inside and outside a main transformer area based on the grid fault oscillogram as claimed in claim 2, wherein the method further comprises:
setting a region where the waveform of the protection switching value has mutation as a first mutation region, and setting a region where the waveform of the trip switching value has mutation as a second mutation region; wherein the second mutated region is located within the first mutated region;
when the main transformer fault is an in-zone fault, if the current waveforms of all phases which are mutated in the main transformer high-voltage side three-phase current waveform and the main transformer high-voltage side three-phase current waveform are both located in the second mutation zone, the protection action of the in-zone fault is determined to be correct;
and when the main transformer fault is an external fault, if the current waveforms of the currents of the high-voltage side three-phase current of the main transformer and the currents of the various phases which are mutated in the three-phase current waveform of the high-voltage side of the main transformer are both located in the first mutation region, determining the protection misoperation of the external fault.
4. The method for determining faults inside and outside a main transformer area based on the grid fault oscillogram as claimed in claim 2, wherein the method further comprises:
and identifying the phase line with the sudden change of the same-phase current waveform as the phase line with the fault in the main transformer fault.
5. The utility model provides a system for judge main district internal and external trouble based on electric wire netting trouble oscillogram which characterized in that includes:
the main transformer fault recording diagram acquisition unit is used for acquiring a main transformer fault recording diagram, and a protection switching value waveform, a trip switching value waveform, a main transformer high-voltage side three-phase current waveform, a main transformer high-voltage side three-phase voltage waveform, a main transformer low-voltage side three-phase current waveform and a main transformer low-voltage side three-phase voltage waveform are formed on the main transformer fault recording diagram;
the main transformer fault detection unit is used for determining that main transformer faults exist if sudden change current waveforms exist in the main transformer high-voltage side three-phase current waveforms and the main transformer low-voltage side three-phase current waveforms and sudden change voltage waveforms exist in the main transformer high-voltage side three-phase voltage waveforms and the main transformer low-voltage side three-phase voltage waveforms;
and the main transformer fault determination unit is used for acquiring the current waveforms of all phases which are mutated and the current waveforms before the respective corresponding mutations in the three-phase current waveforms at the high-voltage side of the main transformer and the three-phase current waveforms at the low-voltage side of the main transformer after the main transformer fault is determined to exist, and determining that the main transformer fault is an in-zone fault or an out-zone fault according to the phase direction changes of the current waveforms of all phases which are mutated in the three-phase current waveforms at the high-voltage side of the main transformer and the three-phase current waveforms at the low-voltage side of the main transformer and the current waveforms.
6. The system for determining faults inside and outside a main transformer area based on a power grid fault oscillogram as claimed in claim 5, wherein the main transformer fault determination unit comprises:
the current waveform acquisition module is used for acquiring current waveforms of all phases which are mutated and current waveforms before respective corresponding mutation in the three-phase current waveforms of the high-voltage side of the main transformer, and acquiring the current waveforms of all phases which are mutated and the current waveforms before respective corresponding mutation in the three-phase current waveforms of the low-voltage side of the main transformer;
the selection module is used for taking out phase lines of current waveforms with sudden changes in the same phase from the three-phase current waveforms on the high-voltage side of the main transformer and the three-phase current waveforms on the low-voltage side of the main transformer;
the first judging module is used for judging that the main transformer fault is an in-region fault if the phase direction of the current waveform with mutation on the current phase line obtained in the main transformer high-voltage side three-phase current waveform is not changed compared with the phase direction of the current waveform with mutation before the mutation, and the phase direction of the current waveform with mutation on the current phase line obtained in the main transformer low-voltage side three-phase current waveform is changed compared with the phase direction of the current waveform with mutation before the mutation;
and the second judging module is used for judging that the main transformer fault is an external fault if the phase direction of the current waveform mutated on the current phase line obtained in the main transformer high-voltage side three-phase current waveform compared with the current waveform mutated before mutation is not changed, and the phase direction of the current waveform mutated on the current phase line obtained in the main transformer low-voltage side three-phase current waveform compared with the current waveform mutated on the current phase line obtained in the main transformer low-voltage side three-phase current waveform is not changed.
7. The system for determining faults inside and outside a main transformer area based on a grid fault oscillogram as claimed in claim 6, wherein the main transformer fault determination unit further comprises:
the sudden change region setting module is used for setting a region where the waveform of the protection switching value has sudden change as a first sudden change region and setting a region where the waveform of the trip switching value has sudden change as a second sudden change region; wherein the second mutated region is located within the first mutated region;
the first identification module is used for determining that the protection action of the fault in the area is correct if the main transformer high-voltage side three-phase current waveform and the current waveforms of all phases which are mutated in the main transformer high-voltage side three-phase current waveform are both located in the second mutation area when the main transformer fault is the fault in the area;
and the second identification module is used for identifying the protection misoperation of the external fault if the main transformer high-voltage side three-phase current waveform and the current waveforms of all phases which are mutated in the main transformer high-voltage side three-phase current waveform are both positioned in the first mutation region when the main transformer fault is the external fault.
8. The system for determining faults inside and outside a main transformer area based on a grid fault oscillogram as claimed in claim 6, wherein the main transformer fault determination unit further comprises:
and the fault phase line identification module is used for identifying the phase line with the sudden change of the same-phase current waveform as the phase line with the fault in the main transformer fault.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106199337B (en) * | 2016-07-20 | 2018-09-25 | 武汉中元华电软件有限公司 | A kind of grid fault analytical method judged based on analog quantity and switching value combination |
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| Title |
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| SAVAGE3232: "保护动作报告及故障录波图的识别", 《百度文库》 * |
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