CN112684261B - Transformer bushing state monitoring method and device - Google Patents
Transformer bushing state monitoring method and device Download PDFInfo
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- CN112684261B CN112684261B CN202011494957.8A CN202011494957A CN112684261B CN 112684261 B CN112684261 B CN 112684261B CN 202011494957 A CN202011494957 A CN 202011494957A CN 112684261 B CN112684261 B CN 112684261B
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Abstract
The invention discloses a method and a device for monitoring the state of a transformer bushing, wherein the method comprises the following steps: acquiring a three-phase grounding current value acquired by the end screen of the transformer bushing; respectively determining a three-phase current amplitude mean value, a three-phase current inter-phase difference value and a three-phase current total amplitude value of the three-phase grounding current value under a preset frequency based on the three-phase grounding current value; judging whether the transformer bushing is abnormal or not according to the three-phase current amplitude mean value and the three-phase current total amplitude; and if the transformer bushing is judged to be abnormal, judging the fault phase of the transformer bushing based on the phase difference value between the three-phase currents. Therefore, monitoring stability is improved, and the cost of monitoring the state of the transformer bushing is reduced.
Description
Technical Field
The invention relates to the technical field of transformer bushing state monitoring, in particular to a transformer bushing state monitoring method and device.
Background
The transformer bushing is an insulating bushing for leading high and low voltage leads inside the transformer to the outside of an oil tank, is used as a lead for insulating the ground and plays a role of fixing the lead, and is one of current-carrying elements of the transformer, which is a precondition for maintaining the normal and stable operation of the transformer.
However, transformer bushings are generally imported for large power transformers and are expensive, and bushing failure is the primary cause of transformer damage. Therefore, how to accurately monitor the abnormality of the transformer bushing and take effective measures in time is an important issue to be considered today.
The capacitance and the dielectric loss of the sleeve are two major indexes representing the state of the sleeve, and the existing sleeve state monitoring technology calculates the capacitance and the dielectric loss of the sleeve by monitoring the amplitude and the phase of grounding current of a tail screen of the sleeve and comparing the amplitude and the phase with the voltage amplitude and the phase of a bus. However, the bus voltage needs to be measured through a mutual inductor, electromagnetic interference exists on site, the mutual inductor has the problems of phase angle error and the like, so that the stability of monitoring the dielectric loss of the bushing insulation is extremely poor, and the capacitance is not sensitive to early faults, so that the monitoring effect of the bushing state is reduced.
Disclosure of Invention
In view of the above, the present invention provides a method and an apparatus for monitoring a bushing state of a transformer, which solve the technical problems in the prior art that the stability of monitoring dielectric loss of bushing insulation is very poor, and capacitance is not sensitive enough to early faults, so that the monitoring effect of the bushing state is reduced.
The invention provides a transformer bushing state monitoring method, which comprises the following steps:
acquiring a three-phase grounding current value acquired by the end screen of the transformer bushing;
respectively determining a three-phase current amplitude mean value, a three-phase current inter-phase difference value and a three-phase current total amplitude value of the three-phase grounding current value under a preset frequency based on the three-phase grounding current value;
judging whether the transformer bushing is abnormal or not according to the three-phase current amplitude mean value and the three-phase current total amplitude;
and if the transformer bushing is judged to be abnormal, judging the fault phase of the transformer bushing based on the phase difference value between the three-phase currents.
Optionally, the step of respectively determining a three-phase current amplitude mean value, a three-phase current phase-to-phase difference value, and a three-phase current total amplitude of the three-phase grounding current value at a preset frequency based on the three-phase grounding current value includes:
acquiring a grounding current value of each phase in the three-phase grounding current values as an intermediate grounding current value;
calculating a first sum of a plurality of said intermediate ground current values;
calculating a first current amplitude value of each intermediate grounding current value under a preset frequency by adopting Fourier transform;
calculating the total three-phase current amplitude of the first sum under the preset frequency by adopting Fourier transform;
and determining the mean value of the three-phase current amplitude values and the phase difference value between the three-phase currents according to the plurality of first current amplitude values.
Optionally, the step of determining whether the transformer bushing is abnormal according to the three-phase current amplitude mean value and the three-phase current total amplitude includes:
calculating a first product of the three-phase current amplitude mean value and a preset threshold coefficient;
comparing the first product with the total three-phase current amplitude;
if the first product is larger than the total amplitude of the three-phase current, judging that the transformer bushing is not abnormal;
and if the first product is less than or equal to the total amplitude of the three-phase current, judging that the transformer bushing is abnormal.
Optionally, the transformer bushing includes a first phase, a second phase, and a third phase, the three-phase current-to-current phase difference values include a first phase difference value between the first phase and the second phase, a second phase difference value between the second phase and the third phase, and a third phase difference value between the third phase and the first phase, the three-phase current-to-current phase difference values include a first phase difference value, a second phase difference value, and a third phase difference value, and if it is determined that the transformer bushing is abnormal, the step of determining a faulty phase of the transformer bushing based on the three-phase current-to-current phase difference values includes:
if the transformer bushing is judged to be abnormal, respectively calculating a first absolute difference value, a second absolute difference value and a third absolute difference value between the first phase difference value, the second phase difference value and the third phase difference value and a preset angle value;
if the first absolute difference value is the minimum value, determining that the third phase is a fault phase;
if the second absolute difference value is the minimum value, determining that the first phase is a fault phase;
and if the third absolute difference value is the minimum value, determining that the second phase is a fault phase.
Optionally, the three-phase grounding current value is synchronously acquired through a preset data acquisition card, and the acquisition step length and the acquisition duration corresponding to each phase of the three-phase grounding current value are equal.
The invention also provides a transformer bushing state monitoring device, which comprises:
the three-phase grounding current value acquisition module is used for acquiring a three-phase grounding current value acquired by the end screen of the transformer bushing;
the three-phase current numerical value calculation module is used for respectively determining a three-phase current amplitude mean value, a three-phase current phase difference value and a three-phase current total amplitude value of the three-phase grounding current value under a preset frequency based on the three-phase grounding current value;
the abnormity judgment module is used for judging whether the transformer bushing is abnormal or not according to the three-phase current amplitude mean value and the three-phase current total amplitude;
and the fault phase judgment module is used for judging the fault phase of the transformer bushing based on the phase difference value between the three-phase currents if the transformer bushing is judged to be abnormal.
Optionally, the three-phase current value calculation module includes:
the intermediate grounding current value determining submodule is used for acquiring the grounding current value of each phase in the three-phase grounding current values as an intermediate grounding current value;
a first sum value operator module for calculating a first sum value of the plurality of intermediate ground current values;
the first current amplitude calculation submodule is used for calculating a first current amplitude of each intermediate grounding current value under a preset frequency by adopting Fourier transform;
the three-phase current total amplitude calculation submodule is used for calculating the three-phase current total amplitude of the first sum under the preset frequency by adopting Fourier transform;
and the current mean value and difference value determining submodule is used for determining the three-phase current amplitude mean value and the three-phase current phase difference value according to the plurality of first current amplitude values.
Optionally, the abnormality determining module includes:
the first product calculation submodule is used for calculating a first product of the three-phase current amplitude mean value and a preset threshold coefficient;
the comparison submodule is used for comparing the first product with the total amplitude of the three-phase current;
the abnormity negation submodule is used for judging that the transformer bushing is not abnormal if the first product is larger than the total amplitude of the three-phase current;
and the abnormity determination submodule is used for determining that the transformer bushing is abnormal if the first product is less than or equal to the total amplitude of the three-phase current.
Optionally, the transformer bushing includes a first phase, a second phase, and a third phase, the three-phase inter-current phase difference values include a first phase difference value between the first phase and the second phase, a second phase difference value between the second phase and the third phase, and a third phase difference value between the third phase and the first phase, the three-phase inter-current phase difference values include a first phase difference value, a second phase difference value, and a third phase difference value, and the fault phase determination module includes:
the phase difference value determining submodule is used for respectively calculating a first absolute difference value, a second absolute difference value and a third absolute difference value between the first phase difference value, the second phase difference value and the third phase difference value and a preset angle value if the transformer bushing is judged to be abnormal;
the first fault phase determination submodule is used for determining that the third phase is a fault phase if the first absolute difference value is the minimum value;
a second fault phase determination submodule, configured to determine that the first phase is a fault phase if the second absolute difference is a minimum value;
and the third fault phase determination submodule is used for determining the second phase as a fault phase if the third absolute difference value is the minimum value.
Optionally, the three-phase grounding current value is synchronously acquired through a preset data acquisition card, and the acquisition step length and the acquisition duration corresponding to each phase of the three-phase grounding current value are equal.
According to the technical scheme, the invention has the following advantages:
according to the method, the three-phase current amplitude mean value, the three-phase current interval phase difference value and the three-phase current total amplitude of the three-phase grounding current value under the preset frequency are respectively determined through the obtained three-phase grounding current value of the end screen of the transformer bushing, whether the transformer bushing is abnormal or not is judged by combining the further comparison of the three-phase current amplitude mean value and the three-phase current total amplitude, if the transformer bushing is abnormal, the fault phase of the transformer bushing is judged based on the three-phase current interval phase difference value, and therefore the follow-up further analysis or power failure test can be conducted on the fault phase. Therefore, the technical problem that in the prior art, the stability of monitoring the dielectric loss of the bushing insulation is extremely poor, and the capacitance is not sensitive enough to early faults, so that the monitoring effect of the bushing state is reduced is solved, the monitoring stability is improved, and the cost of monitoring the bushing state of the transformer is reduced.
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 described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
Fig. 1 is a flowchart illustrating steps of a transformer bushing status monitoring method according to an embodiment of the present invention;
fig. 2 is a flowchart illustrating steps of a transformer bushing status monitoring method according to an alternative embodiment of the present invention;
fig. 3 is a schematic structural diagram of a transformer bushing state monitoring device according to an embodiment of the present invention;
fig. 4 is a block diagram of a transformer bushing state monitoring apparatus according to an embodiment of the present invention.
Detailed Description
The embodiment of the invention provides a method and a device for monitoring the state of a transformer bushing, which are used for solving the technical problems that the stability of monitoring the dielectric loss of bushing insulation is extremely poor, and the capacitance is not sensitive to early faults, so that the monitoring effect of the state of the bushing is reduced.
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, fig. 1 is a flowchart illustrating steps of a transformer bushing state monitoring method according to an embodiment of the present invention.
The invention provides a transformer bushing state monitoring method, which comprises the following steps:
in the embodiment of the invention, when the state of the transformer bushing is monitored, the three-phase grounding current value acquired by the end screen of the transformer bushing can be directly acquired.
It should be noted that the three-phase grounding current value refers to a grounding current value respectively corresponding to each phase of the transformer bushing end screen. For example, the transformer bushing end screen corresponds to A, B and C three phases respectively, and the obtained three-phase grounding current value can comprise A-phase bushing end screen grounding current
B-phase casing end screen grounding current
And C phase casing end screen grounding current
102, respectively determining a three-phase current amplitude mean value, a three-phase current inter-phase difference value and a three-phase current total amplitude value of the three-phase grounding current value under a preset frequency based on the three-phase grounding current value;
after the three-phase grounding current value is obtained, the three-phase current amplitude mean value of the three-phase grounding current value at the preset frequency and the phase difference value between the three-phase currents, such as the phase difference, are respectively determined
And
and also the total amplitude of the three-phase current.
Wherein the three-phase difference can be recorded in the form of an angle.
103, judging whether the transformer bushing is abnormal or not according to the three-phase current amplitude mean value and the three-phase current total amplitude;
in the embodiment of the invention, in order to judge whether the transformer bushing is abnormal or not, comparison operation can be further performed through the three-phase current amplitude mean value and the three-phase current total amplitude to determine whether the transformer bushing is abnormal or not.
And 104, if the transformer bushing is judged to be abnormal, judging the fault phase of the transformer bushing based on the phase difference value between the three-phase currents.
When the transformer bushing is determined to be abnormal, the method can be based on the phase difference value between three-phase currents
And
and determining the minimum value of the phase difference value, thereby determining the fault phase of the transformer bushing so as to carry out further analysis or power failure test on the fault phase subsequently.
In the embodiment of the invention, the three-phase current amplitude mean value, the three-phase current phase difference value and the three-phase current total amplitude of the three-phase grounding current value under the preset frequency are respectively determined through the obtained three-phase grounding current value of the end screen of the transformer bushing, the three-phase current amplitude mean value and the three-phase current total amplitude are combined for further comparison, whether the transformer bushing is abnormal or not is judged, if the transformer bushing is abnormal, the fault phase of the transformer bushing is judged based on the three-phase current phase difference value, and further analysis or power failure test can be carried out on the fault phase subsequently. Therefore, the technical problem that in the prior art, the stability of monitoring the dielectric loss of the bushing insulation is extremely poor, and the capacitance is not sensitive enough to early faults, so that the monitoring effect of the bushing state is reduced is solved, the monitoring stability is improved, and the cost of monitoring the bushing state of the transformer is reduced.
Referring to fig. 2, fig. 2 is a flowchart illustrating steps of a transformer bushing status monitoring method according to an alternative embodiment of the present invention.
The invention provides a transformer bushing state monitoring method, which comprises the following steps:
optionally, step 202 may include the following sub-steps:
acquiring a grounding current value of each phase in the three-phase grounding current values as an intermediate grounding current value;
calculating a first sum of a plurality of said intermediate ground current values;
calculating a first current amplitude value of each intermediate grounding current value under a preset frequency by adopting Fourier transform;
calculating the total three-phase current amplitude of the first sum under the preset frequency by adopting Fourier transform;
and determining the mean value of the three-phase current amplitude values and the phase difference value between the three-phase currents according to the plurality of first current amplitude values.
In specific implementation, the grounding current value of each phase in the three-phase grounding current values is obtained as an intermediate grounding current value, namely, the grounding current of the A-phase sleeve end screen
B-phase casing end screen grounding current
And C phase casing end screen grounding current
And calculates a first sum of the intermediate ground current values
Respectively calculating a first current amplitude I of each intermediate grounding current value under a preset frequency by adopting Fourier transformA、IBAnd ICAnd the total amplitude I of the three-phase current of the first sum at a preset frequencySFinally, determining the mean value of the three-phase current amplitude values according to a plurality of first current amplitude valuesIAVEAnd phase difference between three phase currents
The phase difference between the three phase currents may be recorded in the form of an angle.
Wherein the mean value of the three-phase current amplitudes I can be determined by the following formulaAVE：
Optionally, the preset frequency may be selected to be 50 Hz.
in the embodiment of the present invention, the first product may be calculated by using the three-phase current amplitude mean value and a preset threshold coefficient, where the preset threshold coefficient may be 0.5.
and step 206, if the first product is smaller than or equal to the total amplitude of the three-phase current, determining that the transformer bushing is abnormal.
In a specific implementation, whether the transformer bushing is abnormal or not can be judged through the following formula:
IS＜IAVEl (absence of anomalies)
IS≥IAVEL (presence of anomaly)
And step 207, if the transformer bushing is judged to be abnormal, judging the fault phase of the transformer bushing based on the phase difference value between the three-phase currents.
In one example of the present invention, the transformer bushing includes a first phase a, a second phase B, and a third phase C, and the three-phase current phase difference includes a phase difference between the first phase a and the second phase BFirst phase difference value
A second phase difference value between the second phase B and the third phase C
And a third phase difference value between the third phase C and the first phase A
Step 207 may comprise the following sub-steps:
if the transformer bushing is judged to be abnormal, respectively calculating a first absolute difference value, a second absolute difference value and a third absolute difference value between the first phase difference value, the second phase difference value and the third phase difference value and a preset angle value;
if the first absolute difference value is the minimum value, determining that the third phase is a fault phase;
if the second absolute difference value is the minimum value, determining that the first phase is a fault phase;
and if the third absolute difference value is the minimum value, determining that the second phase is a fault phase.
In the embodiment of the invention, when the transformer bushing is judged to have the abnormality, the first phase difference values are respectively calculated
The second phase difference value
And said third phase difference value
The first absolute difference, the second absolute difference and the third absolute difference from the preset angle value may be as follows:
if it is
If the value is the minimum value, the C phase is possibly a fault phase; if it is
If the value is the minimum value, the A phase is possibly a fault phase;
at a minimum, phase B may be the failed phase.
Further, further analysis or a power failure test is performed for the abnormal phase.
Optionally, the three-phase grounding current value is synchronously acquired through a preset data acquisition card, and the acquisition step length and the acquisition duration corresponding to each phase of the three-phase grounding current value are equal.
Referring to fig. 3, fig. 3 is a schematic structural diagram illustrating a transformer bushing state monitoring apparatus according to an embodiment of the present invention.
Aiming at the end screen grounding of the phase A bushing 301, the phase B bushing 302 and the phase C bushing 303, an end screen grounding current is measured by respectively adopting a phase A micro-current sensor 304, a phase B micro-current sensor 305 and a phase C micro-current sensor 306.
The acquisition board 307 acquires and stores the three-phase end screen current, and the same duration and step length setting is adopted among the three phases during acquisition.
The microprocessor 308 sums the acquired end screen currents, performs fourier transform calculation, and performs judgment and analysis of casing abnormality.
In the embodiment of the invention, on the basis of original end screen current monitoring, an end screen current analog value summing module is added, under an ideal state, a three-phase end screen current vector should be infinitely close to 0, but in practice, three-phase voltage and a bushing cannot be completely consistent or symmetrical, so that the three-phase voltage and the bushing cannot be 0, if the three-phase current and the amplitude exceed a certain value, the fact that an abnormality exists in a bushing of a certain phase, and the fact that the abnormality exists in the bushing of a certain phase basically exists only in the field. Therefore, the analysis of the state of the sleeve can be realized only according to the monitoring of the end screen current of the sleeve, the monitoring stability is improved, and the cost of the monitoring device is reduced.
According to the embodiment of the invention, the three-phase current amplitude mean value, the three-phase current phase difference value and the three-phase current total amplitude of the three-phase grounding current value under the preset frequency are respectively determined through the obtained three-phase grounding current value of the end screen of the transformer bushing, whether the transformer bushing is abnormal or not is judged by combining the further comparison of the three-phase current amplitude mean value and the three-phase current total amplitude, if the transformer bushing is abnormal, the fault phase of the transformer bushing abnormality is judged based on the three-phase current phase difference value, so that the follow-up further analysis or power failure test can be carried out aiming at the fault phase. Therefore, the technical problem that in the prior art, the stability of monitoring the dielectric loss of the bushing insulation is extremely poor, and the capacitance is not sensitive enough to early faults, so that the monitoring effect of the bushing state is reduced is solved, the monitoring stability is improved, and the cost of monitoring the bushing state of the transformer is reduced.
Referring to fig. 4, fig. 4 is a block diagram illustrating a transformer bushing status monitoring apparatus according to an embodiment of the present invention.
The invention also provides a transformer bushing state monitoring device, which comprises:
a three-phase grounding current value obtaining module 401, configured to obtain a three-phase grounding current value collected by a tap of a transformer bushing;
a three-phase current numerical calculation module 402, configured to determine, based on the three-phase ground current value, a three-phase current amplitude mean value, a three-phase current phase-to-phase current phase difference value, and a three-phase current total amplitude of the three-phase ground current value at a preset frequency, respectively;
an anomaly determination module 403, configured to determine whether the transformer bushing is anomalous according to the three-phase current amplitude mean value and the three-phase current total amplitude;
and a fault phase determination module 404, configured to determine a fault phase of the transformer bushing based on the phase difference between the three-phase currents if it is determined that the transformer bushing is abnormal.
Optionally, the three-phase current value calculating module 402 includes:
the intermediate grounding current value determining submodule is used for acquiring the grounding current value of each phase in the three-phase grounding current values as an intermediate grounding current value;
a first sum value operator module for calculating a first sum value of the plurality of intermediate ground current values;
the first current amplitude calculation submodule is used for calculating a first current amplitude of each intermediate grounding current value under a preset frequency by adopting Fourier transform;
the three-phase current total amplitude calculation submodule is used for calculating the three-phase current total amplitude of the first sum under the preset frequency by adopting Fourier transform;
and the current mean value and difference value determining submodule is used for determining the three-phase current amplitude mean value and the three-phase current phase difference value according to the plurality of first current amplitude values.
Optionally, the abnormality determining module 403 includes:
the first product calculation submodule is used for calculating a first product of the three-phase current amplitude mean value and a preset threshold coefficient;
the comparison submodule is used for comparing the first product with the total amplitude of the three-phase current;
the abnormity negation submodule is used for judging that the transformer bushing is not abnormal if the first product is larger than the total amplitude of the three-phase current;
and the abnormity determination submodule is used for determining that the transformer bushing is abnormal if the first product is less than or equal to the total amplitude of the three-phase current.
Optionally, the transformer bushing includes a first phase, a second phase and a third phase, the three-phase current-to-current phase difference values include a first phase difference value between the first phase and the second phase, a second phase difference value between the second phase and the third phase and a third phase difference value between the third phase and the first phase, and the fault phase determining module 404 includes:
the phase difference value determining submodule is used for respectively calculating a first absolute difference value, a second absolute difference value and a third absolute difference value between the first phase difference value, the second phase difference value and the third phase difference value and a preset angle value if the transformer bushing is judged to be abnormal;
the first fault phase determination submodule is used for determining that the third phase is a fault phase if the first absolute difference value is the minimum value;
a second fault phase determination submodule, configured to determine that the first phase is a fault phase if the second absolute difference is a minimum value;
and the third fault phase determination submodule is used for determining the second phase as a fault phase if the third absolute difference value is the minimum value.
Optionally, the three-phase grounding current value is synchronously acquired through a preset data acquisition card, and the acquisition step length and the acquisition duration corresponding to each phase of the three-phase grounding current value are equal.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (6)
1. A transformer bushing state monitoring method is characterized by comprising the following steps:
acquiring a three-phase grounding current value acquired by the end screen of the transformer bushing;
respectively determining a three-phase current amplitude mean value, a three-phase current inter-phase difference value and a three-phase current total amplitude value of the three-phase grounding current value under a preset frequency based on the three-phase grounding current value;
judging whether the transformer bushing is abnormal or not according to the three-phase current amplitude mean value and the three-phase current total amplitude;
if the transformer bushing is judged to be abnormal, judging a fault phase of the transformer bushing based on the phase difference value between the three-phase currents;
the step of judging whether the transformer bushing is abnormal or not according to the three-phase current amplitude mean value and the three-phase current total amplitude comprises the following steps of:
calculating a first product of the three-phase current amplitude mean value and a preset threshold coefficient;
comparing the first product with the total three-phase current amplitude;
if the first product is larger than the total amplitude of the three-phase current, judging that the transformer bushing is not abnormal;
if the first product is smaller than or equal to the total amplitude of the three-phase current, judging that the transformer bushing is abnormal;
the transformer bushing comprises a first phase, a second phase and a third phase, the phase difference value between the three-phase currents comprises a first phase difference value between the first phase and the second phase, a second phase difference value between the second phase and the third phase and a third phase difference value between the third phase and the first phase, if the transformer bushing is judged to be abnormal, the step of judging a fault phase of the transformer bushing based on the phase difference value between the three-phase currents comprises the following steps:
if the transformer bushing is judged to be abnormal, respectively calculating a first absolute difference value, a second absolute difference value and a third absolute difference value between the first phase difference value, the second phase difference value and the third phase difference value and a preset angle value;
if the first absolute difference value is the minimum value, determining that the third phase is a fault phase;
if the second absolute difference value is the minimum value, determining that the first phase is a fault phase;
and if the third absolute difference value is the minimum value, determining that the second phase is a fault phase.
2. The transformer bushing state monitoring method according to claim 1, wherein the step of respectively determining a three-phase current amplitude mean value, a three-phase current phase difference value and a three-phase current total amplitude value of the three-phase grounding current value at a preset frequency based on the three-phase grounding current value comprises:
acquiring a grounding current value of each phase in the three-phase grounding current values as an intermediate grounding current value;
calculating a first sum of three of the intermediate ground current values;
calculating a first current amplitude value and a first phase value of each intermediate grounding current value under a preset frequency by adopting Fourier transform;
calculating the total three-phase current amplitude of the first sum under the preset frequency by adopting Fourier transform;
and determining the mean value of the three-phase current amplitude values and the phase difference value between the three-phase currents according to the plurality of first current amplitude values.
3. The transformer bushing state monitoring method according to any one of claims 1-2, wherein the three-phase grounding current values are synchronously acquired through a preset data acquisition card, and the acquisition step length and the acquisition duration corresponding to each phase of the three-phase grounding current values are equal.
4. A transformer bushing condition monitoring device, comprising:
the three-phase grounding current value acquisition module is used for acquiring a three-phase grounding current value acquired by the end screen of the transformer bushing;
the three-phase current numerical value calculation module is used for respectively determining a three-phase current amplitude value, a three-phase current amplitude mean value, a three-phase current phase difference value and a three-phase current total amplitude value of the three-phase grounding current value under a preset frequency based on the three-phase grounding current value;
the abnormity judgment module is used for judging whether the transformer bushing is abnormal or not according to the three-phase current amplitude mean value and the three-phase current total amplitude;
the fault phase judging module is used for judging the fault phase of the transformer bushing based on the phase difference value between the three-phase currents if the transformer bushing is judged to be abnormal;
the abnormality determination module includes:
the first product calculation submodule is used for calculating a first product of the three-phase current amplitude mean value and a preset threshold coefficient;
the comparison submodule is used for comparing the first product with the total amplitude of the three-phase current;
the abnormity negation submodule is used for judging that the transformer bushing is not abnormal if the first product is larger than the total amplitude of the three-phase current;
the abnormality judgment submodule is used for judging that the transformer bushing is abnormal if the first product is smaller than or equal to the total amplitude of the three-phase current;
the transformer bushing comprises a first phase, a second phase and a third phase, the phase difference value between the three-phase currents comprises a first phase difference value between the first phase and the second phase, a second phase difference value between the second phase and the third phase and a third phase difference value between the third phase and the first phase, and the fault phase judgment module comprises:
the phase difference value determining submodule is used for respectively calculating a first absolute difference value, a second absolute difference value and a third absolute difference value between the first phase difference value, the second phase difference value and the third phase difference value and a preset angle value if the transformer bushing is judged to be abnormal;
the first fault phase determination submodule is used for determining that the third phase is a fault phase if the first absolute difference value is the minimum value;
a second fault phase determination submodule, configured to determine that the first phase is a fault phase if the second absolute difference is a minimum value;
and the third fault phase determination submodule is used for determining the second phase as a fault phase if the third absolute difference value is the minimum value.
5. The transformer bushing state monitoring device of claim 4, wherein the three-phase current numerical calculation module comprises:
the intermediate grounding current value determining submodule is used for acquiring the grounding current value of each phase in the three-phase grounding current values as an intermediate grounding current value;
a first sum value operator module for calculating a first sum value of the plurality of intermediate ground current values;
the first current amplitude calculation submodule is used for calculating a first current amplitude of each intermediate grounding current value under a preset frequency by adopting Fourier transform;
the three-phase current total amplitude calculation submodule is used for calculating the three-phase current total amplitude of the first sum under the preset frequency by adopting Fourier transform;
and the current mean value and difference value determining submodule is used for determining the three-phase current amplitude mean value and the three-phase current phase difference value according to the plurality of first current amplitude values.
6. The transformer bushing state monitoring device according to any one of claims 4-5, wherein the three-phase grounding current values are synchronously collected by a preset data collecting card, and the collecting step length and the collecting time length corresponding to each phase of the three-phase grounding current values are equal.
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