CN113281560A - Method and device for acquiring maximum short-circuit current value of in-service transformer - Google Patents
Method and device for acquiring maximum short-circuit current value of in-service transformer Download PDFInfo
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- CN113281560A CN113281560A CN202110546713.8A CN202110546713A CN113281560A CN 113281560 A CN113281560 A CN 113281560A CN 202110546713 A CN202110546713 A CN 202110546713A CN 113281560 A CN113281560 A CN 113281560A
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- 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
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
- G01R19/16571—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing AC or DC current with one threshold, e.g. load current, over-current, surge current or fault current
Abstract
The application relates to the technical field of operation and maintenance of power transformation equipment, and discloses a method and a device for acquiring a maximum short-circuit current value of an in-operation transformer. According to the method, historical fault current waveforms of the operating transformer when single short circuit, interphase short circuit and three-phase short circuit occur are firstly obtained, then zero sequence impedance, positive sequence impedance and negative sequence impedance of the operating transformer in different short circuit modes are determined according to the historical fault current waveforms, real-time voltage values of the operating transformer are further obtained, and the maximum short circuit current values of the current operating transformer are determined by combining the zero sequence impedance, the positive sequence impedance and the negative sequence impedance of the operating transformer in different short circuit modes. The method and the device can determine the maximum current value of the in-transit transformer in real time, and solve the technical problem that the in-transit transformer is difficult to check for short-circuit resistance at present.
Description
Technical Field
The application relates to the technical field of operation and maintenance of power transformation equipment, in particular to a method and a device for acquiring a maximum short-circuit current value of an in-operation transformer.
Background
As one of the important devices of the power grid, the quality of the operation of the power transformer directly affects whether the power grid can operate safely and stably. Due to design, manufacture or maintenance of the power transformer, short circuit damage often occurs during operation. If a short circuit occurs in the system operation process, especially if the main transformer directly connected with the generator is damaged, the generator is forced to stop generating power, and then large-area power failure occurs, which seriously affects the reliability of power supply, and generally speaking, the overhaul period of the transformer is often long, which causes huge loss to the power grid and user units.
At present, before a power transformer is put into operation, the power transformer is checked for short-circuit resistance in advance, and the maximum short-circuit current value which can be borne by the power transformer is determined. The larger the maximum short-circuit current value is, the stronger the short-circuit resistance of the power transformer is. And according to the maximum short-circuit current value, suggestions are provided for the manufacturing link and the operating link of the power transformer, the short-circuit resistance of the power transformer is improved, and a basis is provided for the design and manufacture of manufacturers and the use of users.
However, the research results of checking the short-circuit resistance of the power transformer at present mainly focus on the design stage of the power transformer, and for the transformer which is already put into operation, namely the transformer in operation, if the short-circuit resistance is required to be checked, the power transformer needs to be shut down, the test time is long, and great loss is generated. Therefore, a method for determining the maximum short-circuit current value of the on-load transformer in real time is needed to evaluate the short-circuit resistance of the on-load transformer and take measures to prevent the main transformer from short-circuit damage.
Disclosure of Invention
The application discloses a method and a device for obtaining a maximum short-circuit current value of an in-service transformer, which are used for solving the technical problem that the existing research results about the checking of the short-circuit resistance of the power transformer are mainly concentrated on the design stage of the power transformer and the checking of the short-circuit resistance of the in-service transformer is difficult.
The application discloses in a first aspect a method for obtaining a maximum short-circuit current value of an in-service transformer, comprising:
acquiring a historical fault current waveform of the transformer in operation;
according to the historical fault current waveform, determining zero sequence impedance of the on-line transformer when a single-phase short circuit occurs, positive sequence impedance of the on-line transformer when the single-phase short circuit occurs and negative sequence impedance of the on-line transformer when the single-phase short circuit occurs, determining zero sequence impedance of the on-line transformer when an interphase short circuit occurs, positive sequence impedance of the on-line transformer when the interphase short circuit occurs and negative sequence impedance of the on-line transformer when the three-phase short circuit occurs;
acquiring a real-time voltage value of the on-line transformer;
determining the maximum short-circuit current value when the single-phase short circuit occurs according to the real-time voltage value of the in-service transformer, the zero sequence impedance when the single-phase short circuit occurs, the positive sequence impedance when the single-phase short circuit occurs and the negative sequence impedance when the single-phase short circuit occurs;
determining the maximum short-circuit current value when the interphase short circuit occurs according to the real-time voltage value of the in-service transformer, the zero sequence impedance when the interphase short circuit occurs, the positive sequence impedance when the interphase short circuit occurs and the negative sequence impedance when the interphase short circuit occurs;
determining the maximum short-circuit current value when the three-phase short circuit occurs according to the real-time voltage value of the in-service transformer and the positive sequence impedance when the three-phase short circuit occurs;
determining the maximum short-circuit current value of the on-load transformer, wherein the maximum short-circuit current value of the on-load transformer is the maximum value of the maximum short-circuit current value when the single-phase short circuit occurs, the maximum short-circuit current value when the inter-phase short circuit occurs and the maximum short-circuit current value when the three-phase short circuit occurs.
Optionally, the determining a maximum short-circuit current value when a single-phase short circuit occurs according to the real-time voltage value of the operating transformer, the zero-sequence impedance when the single-phase short circuit occurs, the positive-sequence impedance when the single-phase short circuit occurs, and the negative-sequence impedance when the single-phase short circuit occurs includes:
determining a first single-phase short-circuit current value according to the real-time voltage value and the zero sequence impedance when the single-phase short circuit occurs, determining a second single-phase short-circuit current value according to the real-time voltage value and the positive sequence impedance when the single-phase short circuit occurs, and determining a third single-phase short-circuit current value according to the real-time voltage value and the negative sequence impedance when the single-phase short circuit occurs;
determining the maximum short-circuit current value when the single-phase short circuit occurs, wherein the maximum short-circuit current value when the single-phase short circuit occurs is the maximum value of the first single-phase short-circuit current value, the second single-phase short-circuit current value and the third single-phase short-circuit current value.
Optionally, the determining a maximum short-circuit current value when an inter-phase short circuit occurs according to the real-time voltage value of the in-service transformer, the zero-sequence impedance when the inter-phase short circuit occurs, the positive-sequence impedance when the inter-phase short circuit occurs, and the negative-sequence impedance when the inter-phase short circuit occurs includes:
determining a first inter-phase short circuit current value according to the real-time voltage value and the zero sequence impedance when the inter-phase short circuit occurs, determining a second inter-phase short circuit current value according to the real-time voltage value and the positive sequence impedance when the inter-phase short circuit occurs, and determining a third inter-phase short circuit current value according to the real-time voltage value and the negative sequence impedance when the inter-phase short circuit occurs;
and determining the maximum short-circuit current value when the inter-phase short circuit occurs, wherein the maximum short-circuit current value when the inter-phase short circuit occurs is the maximum value of the first inter-phase short-circuit current value, the second inter-phase short-circuit current value and the third inter-phase short-circuit current value.
Optionally, the historical fault current waveform includes: fault current waveforms when a single-phase short circuit occurs a plurality of times, fault current waveforms when an interphase short circuit occurs a plurality of times, and fault current waveforms when a three-phase short circuit occurs a plurality of times.
The second aspect of the present application discloses an apparatus for obtaining a maximum short-circuit current value of an on-load transformer, which is applied to the method for obtaining a maximum short-circuit current value of an on-load transformer disclosed in the first aspect of the present application, and the apparatus for obtaining a maximum short-circuit current value of an on-load transformer includes:
the waveform acquisition module is used for acquiring the historical fault current waveform of the transformer in operation;
the impedance determination module is used for determining zero sequence impedance of the on-line transformer when a single-phase short circuit occurs, positive sequence impedance of the on-line transformer when the single-phase short circuit occurs and negative sequence impedance of the on-line transformer when the single-phase short circuit occurs according to the historical fault current waveform, determining zero sequence impedance of the on-line transformer when an interphase short circuit occurs, positive sequence impedance of the on-line transformer when the interphase short circuit occurs and negative sequence impedance of the on-line transformer when the interphase short circuit occurs, and determining positive sequence impedance of the on-line transformer when the three-phase short circuit occurs;
the real-time voltage value acquisition module is used for acquiring the real-time voltage value of the on-line transformer;
the first short-circuit current value acquisition module is used for determining the maximum short-circuit current value when the single-phase short circuit occurs according to the real-time voltage value of the in-service transformer, the zero sequence impedance when the single-phase short circuit occurs, the positive sequence impedance when the single-phase short circuit occurs and the negative sequence impedance when the single-phase short circuit occurs;
the second short-circuit current value acquisition module is used for determining the maximum short-circuit current value when the interphase short circuit occurs according to the real-time voltage value of the in-service transformer, the zero sequence impedance when the interphase short circuit occurs, the positive sequence impedance when the interphase short circuit occurs and the negative sequence impedance when the interphase short circuit occurs;
the third short-circuit current value acquisition module is used for determining the maximum short-circuit current value when the three-phase short circuit occurs according to the real-time voltage value of the in-operation transformer and the positive sequence impedance when the three-phase short circuit occurs;
the maximum short-circuit current value obtaining module is used for determining the maximum short-circuit current value of the transformer in operation, wherein the maximum short-circuit current value of the transformer in operation is the maximum value among the maximum short-circuit current value when the single-phase short circuit occurs, the maximum short-circuit current value when the interphase short circuit occurs and the maximum short-circuit current value when the three-phase short circuit occurs.
Optionally, the first short-circuit current value obtaining module includes:
the single-phase short-circuit current value obtaining unit is used for determining a first single-phase short-circuit current value according to the real-time voltage value and the zero sequence impedance when the single-phase short circuit occurs, determining a second single-phase short-circuit current value according to the real-time voltage value and the positive sequence impedance when the single-phase short circuit occurs, and determining a third single-phase short-circuit current value according to the real-time voltage value and the negative sequence impedance when the single-phase short circuit occurs;
and a single-phase short-circuit-time maximum short-circuit current value determining unit, configured to determine a maximum short-circuit current value when the single-phase short circuit occurs, where the maximum short-circuit current value when the single-phase short circuit occurs is a maximum value of the first single-phase short-circuit current value, the second single-phase short-circuit current value, and the third single-phase short-circuit current value.
Optionally, the second short-circuit current value obtaining module includes:
an inter-phase short circuit current value obtaining unit, configured to determine a first inter-phase short circuit current value according to the real-time voltage value and the zero sequence impedance when an inter-phase short circuit occurs, determine a second inter-phase short circuit current value according to the real-time voltage value and the positive sequence impedance when an inter-phase short circuit occurs, and determine a third inter-phase short circuit current value according to the real-time voltage value and the negative sequence impedance when an inter-phase short circuit occurs;
and the maximum short-circuit current value determining unit is used for determining the maximum short-circuit current value when the inter-phase short circuit occurs, wherein the maximum short-circuit current value when the inter-phase short circuit occurs is the maximum value of the first inter-phase short-circuit current value, the second inter-phase short-circuit current value and the third inter-phase short-circuit current value.
The application relates to the technical field of operation and maintenance of power transformation equipment, and discloses a method and a device for acquiring a maximum short-circuit current value of an in-operation transformer. According to the method, historical fault current waveforms of the operating transformer when single short circuit, interphase short circuit and three-phase short circuit occur are firstly obtained, then zero sequence impedance, positive sequence impedance and negative sequence impedance of the operating transformer in different short circuit modes are determined according to the historical fault current waveforms, real-time voltage values of the operating transformer are further obtained, and the maximum short circuit current values of the current operating transformer are determined by combining the zero sequence impedance, the positive sequence impedance and the negative sequence impedance of the operating transformer in different short circuit modes. The method and the device can determine the maximum current value of the in-transit transformer in real time, and solve the technical problem that the in-transit transformer is difficult to check for short-circuit resistance at present.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic workflow diagram of a method for obtaining a maximum short-circuit current value of an in-service transformer disclosed in an embodiment of the present application;
fig. 2 is a schematic structural diagram of an apparatus for acquiring a maximum short-circuit current value of an in-service transformer disclosed in an embodiment of the present application.
Detailed Description
In order to solve the technical problem that the short-circuit resistance of the in-service transformer is difficult to check at present, the application discloses a method and a device for acquiring the maximum short-circuit current value of the in-service transformer through the following two embodiments.
The first embodiment of the present application discloses a method for obtaining a maximum short-circuit current value of an on-load transformer, referring to a work flow diagram shown in fig. 1, the method for obtaining the maximum short-circuit current value of the on-load transformer includes:
step S101, acquiring historical fault current waveforms of the transformer in operation.
Further, the historical fault current waveform includes: fault current waveforms when a single-phase short circuit occurs a plurality of times, fault current waveforms when an interphase short circuit occurs a plurality of times, and fault current waveforms when a three-phase short circuit occurs a plurality of times.
Transformers operating in a power grid can suffer from multiple short circuit impacts due to lightning strikes, small animals and the like, and the short circuit forms include single-phase short circuits, interphase short circuits and three-phase short circuits. When short circuit occurs, the protection device of the transformer records the relevant fault voltage and current. The fault recording device of the on-line transformer is used for deriving the historical fault current waveform of the on-line transformer when a single short circuit, an interphase short circuit and a three-phase short circuit occur.
Step S102, determining zero sequence impedance, positive sequence impedance and negative sequence impedance of the transformer in operation when single-phase short circuit occurs according to the historical fault current waveform, determining zero sequence impedance, positive sequence impedance and negative sequence impedance of the transformer in operation when interphase short circuit occurs, and determining positive sequence impedance of the transformer in operation when three-phase short circuit occurs.
In the practical application process, the short-circuit fault voltage and current conditions under different working conditions are calculated for multiple times through an identification algorithm according to multiple times of historical fault current waveforms. And according to the identified zero sequence, positive sequence and negative sequence networks under different short circuit conditions and the current operation condition, the impedance values of the zero sequence, positive sequence and negative sequence networks of the operation transformer under different short circuit modes can be calculated.
And step S103, acquiring the real-time voltage value of the on-line transformer.
In the practical application process, according to the voltage condition of the real-time operation of the in-service transformer and according to the impedance values of the zero sequence network, the positive sequence network and the negative sequence network of the in-service transformer identified in the step S102, the maximum value which may occur to the short-circuit current can be predicted in real time through calculation and result comparison.
And step S104, determining the maximum short-circuit current value when the single-phase short circuit occurs according to the real-time voltage value of the in-service transformer, the zero-sequence impedance when the single-phase short circuit occurs, the positive-sequence impedance when the single-phase short circuit occurs and the negative-sequence impedance when the single-phase short circuit occurs.
Further, the determining a maximum short-circuit current value when a single-phase short circuit occurs according to the real-time voltage value of the operating transformer, the zero-sequence impedance when the single-phase short circuit occurs, the positive-sequence impedance when the single-phase short circuit occurs, and the negative-sequence impedance when the single-phase short circuit occurs includes:
determining a first single-phase short-circuit current value according to the real-time voltage value and the zero sequence impedance when the single-phase short circuit occurs, determining a second single-phase short-circuit current value according to the real-time voltage value and the positive sequence impedance when the single-phase short circuit occurs, and determining a third single-phase short-circuit current value according to the real-time voltage value and the negative sequence impedance when the single-phase short circuit occurs.
Determining the maximum short-circuit current value when the single-phase short circuit occurs, wherein the maximum short-circuit current value when the single-phase short circuit occurs is the maximum value of the first single-phase short-circuit current value, the second single-phase short-circuit current value and the third single-phase short-circuit current value.
In the practical application process, firstly, according to the fault current waveform when single-phase short circuit occurs for multiple times, determining the zero sequence impedance when single-phase short circuit occurs, the positive sequence impedance when single-phase short circuit occurs and the negative sequence impedance when single-phase short circuit occurs, then respectively calculating the impedance value of each sequence network and the current real-time voltage value to obtain three groups of short circuit current values, and taking the maximum value of the short circuit current values to determine the maximum short circuit current value when single-phase short circuit occurs.
And S105, determining the maximum short-circuit current value when the interphase short circuit occurs according to the real-time voltage value of the in-service transformer, the zero-sequence impedance when the interphase short circuit occurs, the positive-sequence impedance when the interphase short circuit occurs and the negative-sequence impedance when the interphase short circuit occurs.
Further, the determining a maximum short circuit current value when the inter-phase short circuit occurs according to the real-time voltage value of the in-service transformer, the zero sequence impedance when the inter-phase short circuit occurs, the positive sequence impedance when the inter-phase short circuit occurs, and the negative sequence impedance when the inter-phase short circuit occurs includes:
and determining a first inter-phase short-circuit current value according to the real-time voltage value and the zero sequence impedance when the inter-phase short circuit occurs, determining a second inter-phase short-circuit current value according to the real-time voltage value and the positive sequence impedance when the inter-phase short circuit occurs, and determining a third inter-phase short-circuit current value according to the real-time voltage value and the negative sequence impedance when the inter-phase short circuit occurs.
And determining the maximum short-circuit current value when the inter-phase short circuit occurs, wherein the maximum short-circuit current value when the inter-phase short circuit occurs is the maximum value of the first inter-phase short-circuit current value, the second inter-phase short-circuit current value and the third inter-phase short-circuit current value.
In the practical application process, firstly, according to the fault current waveform when the interphase short circuit occurs for a plurality of times, determining the zero sequence impedance when the interphase short circuit occurs, the positive sequence impedance when the interphase short circuit occurs and the negative sequence impedance when the interphase short circuit occurs, then respectively calculating the impedance value of each sequence network and the current real-time voltage value to obtain three groups of short circuit current values, and taking the maximum value of the short circuit current values to determine the maximum short circuit current value when the interphase short circuit occurs.
And step S106, determining the maximum short-circuit current value when the three-phase short circuit occurs according to the real-time voltage value of the transformer in operation and the positive sequence impedance when the three-phase short circuit occurs.
In the practical application process, firstly, the positive sequence impedance when the three-phase short circuit occurs is determined according to the fault current waveform when the three-phase short circuit occurs for many times, and then the positive sequence impedance when the three-phase short circuit occurs and the current real-time voltage value are calculated to determine the maximum short circuit current value when the three-phase short circuit occurs.
And determining the current possible short-circuit current value by a formula I of U/Zk, wherein I represents the short-circuit current value corresponding to the impedance value of any network in any short-circuit form, U represents a real-time voltage value, and Zk represents the impedance value of any network in any short-circuit form.
In the actual operation process, after the step S103 is executed to obtain the real-time voltage value of the on-load transformer, the steps S104, S105 and S106 may be performed simultaneously.
Step S107, determining the maximum short-circuit current value of the transformer in operation, wherein the maximum short-circuit current value of the transformer in operation is the maximum value of the maximum short-circuit current value when the single-phase short circuit occurs, the maximum short-circuit current value when the interphase short circuit occurs and the maximum short-circuit current value when the three-phase short circuit occurs.
The method for obtaining the maximum short-circuit current value of the transformer in operation disclosed in the above embodiments of the present application includes firstly deriving a historical fault current waveform of the transformer in operation when a single short circuit, an interphase short circuit, and a three-phase short circuit occur, then determining a zero sequence impedance, a positive sequence impedance, and a negative sequence impedance of the transformer in operation in different short circuit forms according to the historical fault current waveform, further obtaining a real-time voltage value of the transformer in operation, and determining the maximum short-circuit current value of the transformer in operation by combining the zero sequence impedance, the positive sequence impedance, and the negative sequence impedance of the transformer in operation in different short circuit forms. The method and the device can determine the maximum current value of the in-transit transformer in real time, and solve the technical problem that the in-transit transformer is difficult to check for short-circuit resistance at present.
The following are embodiments of the apparatus of the present application that may be used to perform embodiments of the method of the present application. For details which are not disclosed in the embodiments of the apparatus of the present application, reference is made to the embodiments of the method of the present application.
The second embodiment of the present application discloses an apparatus for obtaining a maximum short-circuit current value of an on-load transformer, which is applied to the method for obtaining a maximum short-circuit current value of an on-load transformer disclosed in the first embodiment of the present application, and referring to a schematic structural diagram shown in fig. 2, the apparatus for obtaining a maximum short-circuit current value of an on-load transformer includes:
and the waveform acquisition module 10 is used for acquiring the historical fault current waveform of the transformer in operation.
And the impedance determining module 20 is used for determining the zero sequence impedance of the operating transformer when a single-phase short circuit occurs, the positive sequence impedance of the operating transformer when the single-phase short circuit occurs and the negative sequence impedance of the operating transformer when the single-phase short circuit occurs according to the historical fault current waveform, determining the zero sequence impedance of the operating transformer when an interphase short circuit occurs, the positive sequence impedance of the operating transformer when the interphase short circuit occurs and the negative sequence impedance of the operating transformer when the interphase short circuit occurs, and determining the positive sequence impedance of the operating transformer when the three-phase short circuit occurs.
And the real-time voltage value acquisition module 30 is configured to acquire a real-time voltage value of the on-line transformer.
The first short-circuit current value obtaining module 40 is configured to determine a maximum short-circuit current value when a single-phase short circuit occurs according to the real-time voltage value of the transformer in operation, the zero-sequence impedance when the single-phase short circuit occurs, the positive-sequence impedance when the single-phase short circuit occurs, and the negative-sequence impedance when the single-phase short circuit occurs.
And the second short-circuit current value obtaining module 50 is configured to determine the maximum short-circuit current value when an inter-phase short circuit occurs according to the real-time voltage value of the in-service transformer, the zero-sequence impedance when the inter-phase short circuit occurs, the positive-sequence impedance when the inter-phase short circuit occurs, and the negative-sequence impedance when the inter-phase short circuit occurs.
And a third short-circuit current value obtaining module 60, configured to determine a maximum short-circuit current value when a three-phase short circuit occurs according to the real-time voltage value of the transformer in operation and the positive sequence impedance when the three-phase short circuit occurs.
A maximum short-circuit current value obtaining module 70, configured to determine a maximum short-circuit current value of the transformer in operation, where the maximum short-circuit current value of the transformer in operation is a maximum value of the maximum short-circuit current value when the single-phase short circuit occurs, the maximum short-circuit current value when the inter-phase short circuit occurs, and the maximum short-circuit current value when the three-phase short circuit occurs.
Further, the first short-circuit current value obtaining module 40 includes:
and the single-phase short-circuit current value acquisition unit is used for determining a first single-phase short-circuit current value according to the real-time voltage value and the zero sequence impedance when the single-phase short circuit occurs, determining a second single-phase short-circuit current value according to the real-time voltage value and the positive sequence impedance when the single-phase short circuit occurs, and determining a third single-phase short-circuit current value according to the real-time voltage value and the negative sequence impedance when the single-phase short circuit occurs.
And a single-phase short-circuit-time maximum short-circuit current value determining unit, configured to determine a maximum short-circuit current value when the single-phase short circuit occurs, where the maximum short-circuit current value when the single-phase short circuit occurs is a maximum value of the first single-phase short-circuit current value, the second single-phase short-circuit current value, and the third single-phase short-circuit current value.
Further, the second short-circuit current value obtaining module 50 includes:
and the inter-phase short-circuit current value acquisition unit is used for determining a first inter-phase short-circuit current value according to the real-time voltage value and the zero sequence impedance when the inter-phase short circuit occurs, determining a second inter-phase short-circuit current value according to the real-time voltage value and the positive sequence impedance when the inter-phase short circuit occurs, and determining a third inter-phase short-circuit current value according to the real-time voltage value and the negative sequence impedance when the inter-phase short circuit occurs.
And the maximum short-circuit current value determining unit is used for determining the maximum short-circuit current value when the inter-phase short circuit occurs, wherein the maximum short-circuit current value when the inter-phase short circuit occurs is the maximum value of the first inter-phase short-circuit current value, the second inter-phase short-circuit current value and the third inter-phase short-circuit current value.
The present application has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to limit the application. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the presently disclosed embodiments and implementations thereof without departing from the spirit and scope of the present disclosure, and these fall within the scope of the present disclosure. The protection scope of this application is subject to the appended claims.
Claims (7)
1. A method for obtaining the maximum short-circuit current value of an in-service transformer is characterized by comprising the following steps:
acquiring a historical fault current waveform of the transformer in operation;
according to the historical fault current waveform, determining zero sequence impedance of the on-line transformer when a single-phase short circuit occurs, positive sequence impedance of the on-line transformer when the single-phase short circuit occurs and negative sequence impedance of the on-line transformer when the single-phase short circuit occurs, determining zero sequence impedance of the on-line transformer when an interphase short circuit occurs, positive sequence impedance of the on-line transformer when the interphase short circuit occurs and negative sequence impedance of the on-line transformer when the three-phase short circuit occurs;
acquiring a real-time voltage value of the on-line transformer;
determining the maximum short-circuit current value when the single-phase short circuit occurs according to the real-time voltage value of the in-service transformer, the zero sequence impedance when the single-phase short circuit occurs, the positive sequence impedance when the single-phase short circuit occurs and the negative sequence impedance when the single-phase short circuit occurs;
determining the maximum short-circuit current value when the interphase short circuit occurs according to the real-time voltage value of the in-service transformer, the zero sequence impedance when the interphase short circuit occurs, the positive sequence impedance when the interphase short circuit occurs and the negative sequence impedance when the interphase short circuit occurs;
determining the maximum short-circuit current value when the three-phase short circuit occurs according to the real-time voltage value of the in-service transformer and the positive sequence impedance when the three-phase short circuit occurs;
determining the maximum short-circuit current value of the on-load transformer, wherein the maximum short-circuit current value of the on-load transformer is the maximum value of the maximum short-circuit current value when the single-phase short circuit occurs, the maximum short-circuit current value when the inter-phase short circuit occurs and the maximum short-circuit current value when the three-phase short circuit occurs.
2. The method for obtaining the maximum short-circuit current value of the on-load transformer according to claim 1, wherein the determining the maximum short-circuit current value when the single-phase short circuit occurs according to the real-time voltage value of the on-load transformer, the zero sequence impedance when the single-phase short circuit occurs, the positive sequence impedance when the single-phase short circuit occurs, and the negative sequence impedance when the single-phase short circuit occurs comprises:
determining a first single-phase short-circuit current value according to the real-time voltage value and the zero sequence impedance when the single-phase short circuit occurs, determining a second single-phase short-circuit current value according to the real-time voltage value and the positive sequence impedance when the single-phase short circuit occurs, and determining a third single-phase short-circuit current value according to the real-time voltage value and the negative sequence impedance when the single-phase short circuit occurs;
determining the maximum short-circuit current value when the single-phase short circuit occurs, wherein the maximum short-circuit current value when the single-phase short circuit occurs is the maximum value of the first single-phase short-circuit current value, the second single-phase short-circuit current value and the third single-phase short-circuit current value.
3. The method for obtaining the maximum short-circuit current value of the on-line transformer according to claim 1, wherein the determining the maximum short-circuit current value when the inter-phase short circuit occurs according to the real-time voltage value of the on-line transformer, the zero sequence impedance when the inter-phase short circuit occurs, the positive sequence impedance when the inter-phase short circuit occurs, and the negative sequence impedance when the inter-phase short circuit occurs comprises:
determining a first inter-phase short circuit current value according to the real-time voltage value and the zero sequence impedance when the inter-phase short circuit occurs, determining a second inter-phase short circuit current value according to the real-time voltage value and the positive sequence impedance when the inter-phase short circuit occurs, and determining a third inter-phase short circuit current value according to the real-time voltage value and the negative sequence impedance when the inter-phase short circuit occurs;
and determining the maximum short-circuit current value when the inter-phase short circuit occurs, wherein the maximum short-circuit current value when the inter-phase short circuit occurs is the maximum value of the first inter-phase short-circuit current value, the second inter-phase short-circuit current value and the third inter-phase short-circuit current value.
4. The method for obtaining the maximum short-circuit current value of the on-load transformer according to claim 1, wherein the historical fault current waveform comprises: fault current waveforms when a single-phase short circuit occurs a plurality of times, fault current waveforms when an interphase short circuit occurs a plurality of times, and fault current waveforms when a three-phase short circuit occurs a plurality of times.
5. An apparatus for obtaining a maximum short-circuit current value of an on-load transformer, which is applied to the method for obtaining a maximum short-circuit current value of an on-load transformer according to any one of claims 1 to 4, the apparatus comprising:
the waveform acquisition module is used for acquiring the historical fault current waveform of the transformer in operation;
the impedance determination module is used for determining zero sequence impedance of the on-line transformer when a single-phase short circuit occurs, positive sequence impedance of the on-line transformer when the single-phase short circuit occurs and negative sequence impedance of the on-line transformer when the single-phase short circuit occurs according to the historical fault current waveform, determining zero sequence impedance of the on-line transformer when an interphase short circuit occurs, positive sequence impedance of the on-line transformer when the interphase short circuit occurs and negative sequence impedance of the on-line transformer when the interphase short circuit occurs, and determining positive sequence impedance of the on-line transformer when the three-phase short circuit occurs;
the real-time voltage value acquisition module is used for acquiring the real-time voltage value of the on-line transformer;
the first short-circuit current value acquisition module is used for determining the maximum short-circuit current value when the single-phase short circuit occurs according to the real-time voltage value of the in-service transformer, the zero sequence impedance when the single-phase short circuit occurs, the positive sequence impedance when the single-phase short circuit occurs and the negative sequence impedance when the single-phase short circuit occurs;
the second short-circuit current value acquisition module is used for determining the maximum short-circuit current value when the interphase short circuit occurs according to the real-time voltage value of the in-service transformer, the zero sequence impedance when the interphase short circuit occurs, the positive sequence impedance when the interphase short circuit occurs and the negative sequence impedance when the interphase short circuit occurs;
the third short-circuit current value acquisition module is used for determining the maximum short-circuit current value when the three-phase short circuit occurs according to the real-time voltage value of the in-operation transformer and the positive sequence impedance when the three-phase short circuit occurs;
the maximum short-circuit current value obtaining module is used for determining the maximum short-circuit current value of the transformer in operation, wherein the maximum short-circuit current value of the transformer in operation is the maximum value among the maximum short-circuit current value when the single-phase short circuit occurs, the maximum short-circuit current value when the interphase short circuit occurs and the maximum short-circuit current value when the three-phase short circuit occurs.
6. The apparatus for obtaining the maximum short-circuit current value of the on-load transformer according to claim 5, wherein the first short-circuit current value obtaining module comprises:
the single-phase short-circuit current value obtaining unit is used for determining a first single-phase short-circuit current value according to the real-time voltage value and the zero sequence impedance when the single-phase short circuit occurs, determining a second single-phase short-circuit current value according to the real-time voltage value and the positive sequence impedance when the single-phase short circuit occurs, and determining a third single-phase short-circuit current value according to the real-time voltage value and the negative sequence impedance when the single-phase short circuit occurs;
and a single-phase short-circuit-time maximum short-circuit current value determining unit, configured to determine a maximum short-circuit current value when the single-phase short circuit occurs, where the maximum short-circuit current value when the single-phase short circuit occurs is a maximum value of the first single-phase short-circuit current value, the second single-phase short-circuit current value, and the third single-phase short-circuit current value.
7. The apparatus for obtaining the maximum short-circuit current value of the on-load transformer according to claim 5, wherein the second short-circuit current value obtaining module comprises:
an inter-phase short circuit current value obtaining unit, configured to determine a first inter-phase short circuit current value according to the real-time voltage value and the zero sequence impedance when an inter-phase short circuit occurs, determine a second inter-phase short circuit current value according to the real-time voltage value and the positive sequence impedance when an inter-phase short circuit occurs, and determine a third inter-phase short circuit current value according to the real-time voltage value and the negative sequence impedance when an inter-phase short circuit occurs;
and the maximum short-circuit current value determining unit is used for determining the maximum short-circuit current value when the inter-phase short circuit occurs, wherein the maximum short-circuit current value when the inter-phase short circuit occurs is the maximum value of the first inter-phase short-circuit current value, the second inter-phase short-circuit current value and the third inter-phase short-circuit current value.
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