CN113419196A - Single-phase transformer winding parameter online monitoring method based on load change - Google Patents
Single-phase transformer winding parameter online monitoring method based on load change 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
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- G01R31/72—Testing of electric windings
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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
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Abstract
The invention discloses a single-phase transformer winding parameter on-line monitoring method based on load change, which belongs to the technical field of transformer winding parameter monitoring methods and comprises the following steps: s1, a T-shaped equivalent circuit of the single-phase transformer is established, a transformer phasor equation is listed according to the T-shaped equivalent circuit, a relation between each input signal of the transformer and winding parameters is established, S2, voltage excitation is kept unchanged when the transformer normally operates, when a load connected to a secondary side changes, other electrical quantities of the transformer change, coordinates alpha beta/dq transformation is carried out in S3 simultaneously in S2 by measuring the voltage and the current of a primary side and a secondary side of the transformer before and after the load changes, and d axes are respectively oriented to primary side voltage phasors
And
and S4, writing the formula in the S3 into a matrix form. According to the invention, the on-line monitoring of the running state of the transformer winding can be realized, and the fault of the transformer winding can be found in time, so that the fault rate of the transformer is effectively reduced, and the service life of the transformer is prolonged.
Description
Technical Field
The invention relates to the technical field of transformer winding parameter monitoring methods, in particular to a single-phase transformer winding parameter online monitoring method based on load change.
Background
In recent years, single-phase distribution transformers are widely applied to low-voltage distribution systems due to the advantages of small size, low manufacturing cost, convenience in installation, high power supply reliability and the like, are mostly used for distribution systems in remote rural areas, provide electric energy for users who do not need to adopt three-phase power supply, and can also be used as large-scale generator transformers, so that the size of a box body can be reduced, the transportation is facilitated, the maintenance cost can be reduced, and the replacement is easy. In a single-phase distribution system, the installation positions of distribution transformers are mostly distributed and numerous, so that it is very necessary to monitor the operation condition of the single-phase distribution transformers in real time. However, the diagnosis of the single-phase transformer winding still mainly uses an off-line method such as a frequency response method, an impedance analysis method and a low-voltage pulse method, so that the winding fault of the transformer cannot be found in time, and the real-time monitoring of the winding parameters cannot be realized.
Disclosure of Invention
The invention aims to provide a single-phase transformer winding parameter online monitoring method based on load change, and solves the problems in the background art.
In order to achieve the purpose, the invention is realized by the following technical scheme: a single-phase transformer winding parameter online monitoring method based on load change comprises the following steps:
s1, establishing a T-shaped equivalent circuit of the single-phase transformer, listing a transformer phasor equation according to the T-shaped equivalent circuit, establishing a relation between each input signal of the transformer and winding parameters, and simplifying the transformer phasor equation to obtain:
s2, the primary and secondary transformers cannot be calculated simultaneously only by using the formula phasor equation in S1Four parameters (R) of the winding of the edge1、X1σ、R′2、X′2σ) Assuming that voltage excitation is kept unchanged during normal operation of the transformer, when the load connected to the secondary side is changed, other electrical quantities of the transformer are changed, and two sets of linear independent phasor equations can be obtained by measuring the voltage and current values of the primary side and the secondary side of the transformer before and after the load change, wherein the equation set is as follows:
s3, transforming the coordinates alpha beta/dq in S2 simultaneously, and the d axes are respectively oriented to the primary side voltage phasors
And
finishing to obtain:
s4, writing the formula in S3 into a matrix form:
matrix phase shift operation is carried out on the transformer winding parameter matrix expression, and the matrix expression of the transformer winding parameter can be obtained:
s5, acquiring the voltage and current of the primary side and the secondary side of the transformer in real time, obtaining the sinusoidal fundamental wave component v 'and the orthogonal component qv' of the fundamental wave through MSOGI-FLL, and uniquely determining the fundamental wave phasor of the corresponding physical quantity by taking the sinusoidal fundamental wave component as an abscissa and the orthogonal component as an ordinate;
s6, obtaining the coordinates of the phasor on the alpha and beta axes in the static rectangular coordinate system according to the step S5, and needing to be the coordinates of the d and q axes in the synchronous rotating rectangular coordinate system with the directional phasor of the primary voltage of the d axis, so the primary and secondary voltage and current phasors of the transformer can be converted into the synchronous rotating coordinate system with the directional phasor of the primary voltage of the d axis by using transformation;
the rotation transformation matrix from the α β stationary coordinate system to the dq synchronous rotating coordinate system is:
s7, after the primary voltage phasor of the d axis is oriented, the primary and secondary voltage phasors and the current phasor of the transformer can obtain corresponding quantities under a dq rotating coordinate system through alpha beta/dq transformation:
further, in operation S2, wherein
Respectively representing the primary and secondary side voltage and current phasors obtained by the first measurement,
and respectively representing the primary and secondary side voltage and current phasors obtained by the second measurement.
Furthermore, in the operation step of S4, the d and q component values of the voltage and current on the primary and secondary sides of the transformer can be obtained in real time by MSOGI-FLL and α β/dq coordinate transformation, and the winding parameters of the transformer can be accurately obtained by only performing two measurements under different load conditions without neglecting the influence of the excitation branch.
Further, in the operation step of S5, the MSOGI-FLL model is used to extract the primary and secondary side voltages, the current fundamental component v 'and the quadrature component qv', the MSOGI-FLL is formed by connecting n number of SOGI-QSGs with different resonant frequencies in parallel, and combines the output signals of each SOGI-QSG link as a feedback link, the FLL module is only connected to the SOGI1 to detect the frequency of the input signal fundamental component, and the other single SOGI-QSG filters out specific harmonics by setting different values of h.
Further, in operation S6, where θ is an angle between the α axis and the β axis, the determination of the θ angle is a key of the coordinate transformation.
The invention provides a single-phase transformer winding parameter online monitoring method based on load change. The method has the following beneficial effects:
1. the method can accurately monitor the winding parameters of the single-phase transformer on line, and the traditional off-line monitoring method cannot realize real-time monitoring.
2. The accurate detection of the winding parameters can make the operation analysis of the transformer more accurate and reliable.
3. Accurate winding parameters will help to find out the transformer with deformed windings in time and perform predictive maintenance on the transformer.
Illustration of the drawings:
FIG. 1 is an equivalent circuit of the transformer of the present invention;
FIG. 2 is a block diagram of the MSOGI-FLL of the present invention;
FIG. 3 is a block diagram of a single SOGI-QSG of the present invention;
FIG. 4 is a schematic diagram of the d-axis primary voltage phasor orientation of the present invention.
Detailed Description
Referring to FIGS. 1-4: a single-phase transformer winding parameter online monitoring method based on load change comprises the following steps:
step one, establishing a T-shaped equivalent circuit of the single-phase transformer, as shown in fig. 1, listing a transformer phasor equation according to the T-shaped equivalent circuit, and establishing a relation between each input signal of the transformer and a winding parameter, as shown in formula (1):
the transformer phasor equation shown in the formula (1) is simplified to obtain:
step two, four parameters (R) of the primary and secondary windings of the transformer cannot be calculated simultaneously only by using the phasor equation shown in the formula (2)1、X1σ、R′2、X′2σ) Therefore, assuming that voltage excitation is kept unchanged during normal operation of the transformer, when the load connected to the secondary side is changed, other electrical quantities of the transformer are changed, and two sets of linearly independent phasor equations can be obtained by measuring the voltage and current values of the primary side and the secondary side of the transformer before and after the load change, as shown in equations (3) and (4):
wherein the content of the first and second substances,
respectively representing the primary and secondary side voltage and current phasors obtained by the first measurement,
respectively representing the primary and secondary side voltage and current phasors obtained by the second measurement;
step three, simultaneously carrying out coordinate alpha beta/dq transformation on the formula (3) and the formula (4), and respectively orienting the d axes to primary side voltage phasors
And
finishing to obtain:
writing the formula (5) into a matrix form as shown in a formula (6).
The formula (6) is a form, and the matrix phase shift operation is performed on the form to obtain a matrix expression of the transformer winding parameters, as shown in the formula (7).
In the above formula, the d and q component values of the voltage and current on the primary side and the secondary side of the transformer can be obtained in real time through MSOGI-FLL and alpha beta/dq coordinate transformation, the influence of the excitation branch is not ignored, and the winding parameters of the transformer can be accurately obtained only by carrying out two times of measurement under different load conditions.
The d and q component values of the primary voltage, the secondary voltage, the primary current and the secondary current of the transformer winding can be obtained by the following method, the primary and secondary voltages, the current fundamental component v 'and the orthogonal quantity qv' of the primary and secondary voltages are extracted by utilizing an MSOGI-FLL model, the MSOGI-FLL is formed by connecting n SOGI-QSG with different resonant frequencies in parallel, the output signals of each SOGI-QSG link are combined to be used as a feedback link, an FLL module is only connected with SOGI1 to detect the frequency of the fundamental component of the input signal, and other single SOGI-QSG filters specific harmonic waves by setting different values of h, so that the extraction accuracy of the fundamental component and the orthogonal component is greatly improved.
And step five, acquiring the voltage and the current of the primary side and the secondary side of the transformer in real time, obtaining the sinusoidal fundamental wave component v 'and the orthogonal component qv' of the fundamental wave through MSOGI-FLL, and uniquely determining the fundamental wave phasor of the corresponding physical quantity by taking the sinusoidal fundamental wave component as an abscissa and the orthogonal component as an ordinate.
Step six, the horizontal (real) axis and the vertical (imaginary) axis are generally represented by the α axis and the β axis. Now, the coordinates of the phasors on the alpha and beta axes in the stationary rectangular coordinate system are obtained, but what we need is the coordinates of the d and q axes in the synchronous rotating rectangular coordinate system with the directional d-axis primary side voltage phasor, so that the primary and secondary side voltage and current phasors of the transformer can be converted into the synchronous rotating coordinate system with the directional d-axis primary side voltage phasor by using transformation, as shown in fig. 4.
The rotation transformation matrix from the α β stationary coordinate system to the dq synchronous rotating coordinate system is:
wherein, theta is an included angle between the alpha axis and the beta axis, and the determination of the theta angle is the key of coordinate transformation.
Seventhly, after the primary voltage phasor of the d axis is oriented, the primary and secondary voltage phasors and the current phasor of the transformer can be converted into corresponding quantities under a dq rotating coordinate system through alpha beta/dq
Therefore, the invention provides the single-phase transformer winding parameter online real-time monitoring method based on load change, which can realize online monitoring of the running state of the transformer winding and timely find the fault of the transformer winding, thereby effectively reducing the fault rate of the transformer and prolonging the service life of the transformer.
The above is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the inventive concept of the present invention, which falls into the protection scope of the present invention.
Claims (6)
1. A single-phase transformer winding parameter online monitoring method based on load change is characterized by comprising the following steps:
s1, establishing a T-shaped equivalent circuit of the single-phase transformer, listing a transformer phasor equation according to the T-shaped equivalent circuit, establishing a relation between each input signal of the transformer and winding parameters, and simplifying the transformer phasor equation to obtain:
s2, four parameters (R) of the primary side and the secondary side of the transformer cannot be calculated simultaneously by only using the formula phasor equation in S11、X1σ、R′2、X′2σ) Assuming that voltage excitation is kept unchanged during normal operation of the transformer, when the load connected to the secondary side is changed, other electrical quantities of the transformer are changed, and two sets of linear independent phasor equations can be obtained by measuring the voltage and current values of the primary side and the secondary side of the transformer before and after the load change, wherein the equation set is as follows:
s3, transforming the coordinates alpha beta/dq in S2 simultaneously, and the d axes are respectively oriented to the primary side voltage phasors
And
finishing to obtain:
s4, writing the formula in S3 into a matrix form:
matrix phase shift operation is carried out on the transformer winding parameter matrix expression, and the matrix expression of the transformer winding parameter can be obtained:
s5, acquiring the voltage and current of the primary side and the secondary side of the transformer in real time, obtaining the sinusoidal fundamental wave component v 'and the orthogonal component qv' of the fundamental wave through MSOGI-FLL, and uniquely determining the fundamental wave phasor of the corresponding physical quantity by taking the sinusoidal fundamental wave component as an abscissa and the orthogonal component as an ordinate;
s6, obtaining the coordinates of the phasor on the alpha and beta axes in the static rectangular coordinate system according to the step S5, and needing to be the coordinates of the d and q axes in the synchronous rotating rectangular coordinate system with the directional phasor of the primary voltage of the d axis, so the primary and secondary voltage and current phasors of the transformer can be converted into the synchronous rotating coordinate system with the directional phasor of the primary voltage of the d axis by using transformation;
the rotation transformation matrix from the α β stationary coordinate system to the dq synchronous rotating coordinate system is:
s7, after the primary voltage phasor of the d axis is oriented, the primary and secondary voltage phasors and the current phasor of the transformer can obtain corresponding quantities under a dq rotating coordinate system through alpha beta/dq transformation:
2. the load change-based single-phase transformer winding parameter online monitoring method according to claim 1, characterized in that: in operation S1, the original relation equation is:
3. the load change-based single-phase transformer winding parameter online monitoring method according to claim 1, characterized in that: in operation S2, wherein
Respectively representing the primary and secondary side voltage and current phasors obtained by the first measurement,
and respectively representing the primary and secondary side voltage and current phasors obtained by the second measurement.
4. The load change-based single-phase transformer winding parameter online monitoring method according to claim 1, characterized in that: in the operation step of S4, the d and q component values of the voltage and current on the primary side and the secondary side of the transformer can be obtained in real time through MSOGI-FLL and alpha beta/dq coordinate transformation, the influence of the excitation branch is not ignored, and the winding parameters of the transformer can be accurately obtained only by carrying out two times of measurement under different load conditions.
5. The load change-based single-phase transformer winding parameter online monitoring method according to claim 1, characterized in that: in the operation step of S5, extracting each original secondary side voltage, current fundamental wave component v 'and orthogonal quantity qv' thereof by using an MSOGI-FLL model, wherein the MSOGI-FLL is formed by connecting n SOGI-QSG with different resonant frequencies in parallel, and combining output signals of each SOGI-QSG link as a feedback link, the FLL module is only connected with SOGI1 for detecting the frequency of the input signal fundamental wave component, and other single SOGI-QSG filters specific harmonic waves by setting different values of h.
6. The load change-based single-phase transformer winding parameter online monitoring method according to claim 1, characterized in that: in operation S6, where θ is an angle between the α axis and the β axis, the determination of the θ angle is the key of the coordinate transformation.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114034923A (en) * | 2021-10-29 | 2022-02-11 | 无锡皓凯利科技有限公司 | Automatic measurement winding broken string and three-phase active power synchrophasor precision leveling system |
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| CN111123162A (en) * | 2019-12-30 | 2020-05-08 | 国网山东省电力公司淄博供电公司 | Three-phase transformer short-circuit parameter online monitoring method based on fundamental wave positive sequence component |
| CN111141956A (en) * | 2019-12-31 | 2020-05-12 | 国网山东省电力公司淄博供电公司 | Single-phase transformer short-circuit parameter online monitoring method based on calculus equation set |
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Patent Citations (4)
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| CN105137278A (en) * | 2015-09-24 | 2015-12-09 | 国网山东省电力公司莱芜供电公司 | SOGI-based single-phase transformer short-circuit parameter on-line real-time identification method |
| CN111044828A (en) * | 2019-12-30 | 2020-04-21 | 国网山东省电力公司淄博供电公司 | Three-phase transformer winding parameter online monitoring method based on positive and negative sequence equations |
| CN111123162A (en) * | 2019-12-30 | 2020-05-08 | 国网山东省电力公司淄博供电公司 | Three-phase transformer short-circuit parameter online monitoring method based on fundamental wave positive sequence component |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114034923A (en) * | 2021-10-29 | 2022-02-11 | 无锡皓凯利科技有限公司 | Automatic measurement winding broken string and three-phase active power synchrophasor precision leveling system |
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