Power transformer winding deformation frequency response detection method

Abstract

The invention discloses a power transformer winding deformation frequency response detection method. According to the method, a detection unit is arranged at the wire outlet end of each winding of a to-be-detected transformer, or the detection unit is arranged on a bushing tap. All the detection units are in network communication connection with the centralized control platform, and the detection units are in network communication connection. The main control CPU controls each detection unit as an excitation unit, a response unit or a suspension unit, sets a deformation frequency response test scheme of the tested winding, measures the reference voltage of the excitation unit at the head end of the tested winding and the response voltage of the response unit at the tail end of the tested winding, completes the frequency response test of the winding, and also can set a configuration full-automatic detection scheme. And the reference voltage of the head-end excitation unit and the response voltage of the tail-end response unit of all the measured windings are measured in sequence, so that the frequency response of all the windings of the transformer is automatically detected. According to the method, the test efficiency and the test safety are improved, the test cost is reduced, and a remote test can be carried out.

Description

Technical Field

[0001] The present invention belongs to the technical field of power equipment measurement, and in particular relates to a method for detecting frequency response of a power transformer winding deformation, that is, detecting the deformation of a power transformer winding by utilizing a frequency response method. Background Art

[0002] Power transformers are crucial equipment in power systems, mostly three-phase or single-phase, and typically consist of multiple windings with high, medium, and low voltages. Current methods for detecting transformer winding deformation primarily employ frequency response methods. These methods generate an amplitude-frequency response curve based on excitation and response data, and use the characteristic values ​​of this curve to determine whether the winding has undergone any deformation. Transformer winding frequency response analysis (FRA) is an important method for determining transformer winding deformation. Existing transformer winding frequency response analysis methods use the leading end of the winding under test as the excitation terminal, the trailing end as the response terminal, and the remaining windings as the floating terminal, testing each phase of the winding in sequence. This method injects a swept frequency signal into the excitation terminal of the transformer winding under test and measures the amplitude ratio of the response voltage at the response terminal to the reference voltage at the excitation terminal to generate a frequency response characteristic curve. Transformer winding deformation (such as displacement, distortion, or insulation damage) can cause changes in distributed capacitance and inductance, thereby altering the shape of the frequency response curve.

[0003] The existing method is to connect the frequency response tester to the excitation end and response end of the winding under test. It is necessary to switch the wiring between the first and last ends of multiple high, medium and low voltage windings in turn, and perform measurement operations in sequence. In particular, the high-voltage windings of the transformer need to be connected in pairs at a high altitude, resulting in a large number of wiring times, which is prone to errors, low test efficiency, and insufficient safety of test personnel. In addition, the existing transformer winding frequency response analysis method relies heavily on manual operation and cannot be remotely tested. How to achieve the transformer winding deformation frequency response test, automatically complete the test with one wiring, and perform remote testing without manual repetitive wiring has become a technical problem that needs to be solved in the transformer winding frequency response analysis method. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for detecting the frequency response of a power transformer winding deformation, so as to improve the test efficiency and test safety of the power transformer winding deformation.

[0005] The method of the present invention is to set a detection unit at the outgoing end of each winding of the transformer to be tested. For transformers whose bushing leads cannot be removed, the detection unit is set on the tap of the bushing end screen; all detection units are connected to the network communication of the centralized control platform, and the network communication connections are between each other.

[0006] All detection units have the same structure, including a main control CPU, a communication module, an excitation module, a sampling module, an excitation module switch, a sampling module switch, a grounding switch and a detection port; the communication module, the excitation module and the sampling module are connected to the main control CPU; the main control CPU is used to receive instructions from the centralized control platform to control the excitation module, sampling module, excitation module switch, sampling module switch and grounding switch of this detection unit.

[0007] The communication module is used for communication between the detection unit and the centralized control platform, as well as with other detection units.

[0008] The excitation module executes the main control CPU instruction to generate a frequency sweep signal, and the signal output end of the excitation module is connected to the detection port through the excitation module switch.

[0009] The sampling module executes the main control CPU instruction to sample the voltage signal. The signal input end of the sampling module is connected to the detection port through the sampling module switch and is grounded through the matching resistor and the grounding switch.

[0010] The detection port is connected to the output terminal of the winding.

[0011] Each detection unit acts as an excitation unit, a response unit or a suspended unit. The main control CPU realizes the switching of the three state units by controlling the closing and opening of the excitation module switch, the sampling module switch and the grounding switch: when the excitation module switch and the sampling module switch are closed and the grounding switch is disconnected, the detection unit is an excitation unit; when the excitation module switch is disconnected and the sampling module switch and the grounding switch are closed, the detection unit is a response unit; when the excitation module switch and the sampling module switch are disconnected and the grounding switch is closed, the detection unit is a suspended unit.

[0012] The centralized control platform realizes the control and data processing of the test process. The centralized control platform sets the detection unit as an excitation unit or a response unit, and sets the detection unit of any winding to any state according to the test requirements; the centralized control platform sends a signal that the tested detection unit is an excitation unit or a response unit to the communication module of the specified detection unit, and sets a deformation frequency response test scheme for the tested winding, that is, the head and tail outgoing ends of a certain winding are defined as the excitation end and the response end, respectively, and the reference voltage of the excitation unit at the head end and the response voltage of the response unit at the tail end of the tested winding are measured to complete the frequency response test of a winding; the centralized control platform sets a configured fully automatic detection scheme according to the connection mode of the tested transformer, defines the detection units at the head and tail outgoing ends of all windings as excitation units and response units, respectively, and measures the reference voltage of the excitation unit at the head end and the response voltage of the response unit at the tail end of all tested windings in turn, thereby realizing automatic detection of the frequency response of all windings of the transformer.

[0013] The specific detection methods are as follows: S1. Detection units are placed at the output terminals of all high-, medium-, and low-voltage windings of the transformer. The housing of each detection unit is grounded, and all detection units are initially in the suspended unit state. S2. Select the detection unit of the first end of the winding under test on the centralized control platform, set it to the excitation unit state, and send a command; the main control CPU of the detection unit receives the command through the communication module, controls the excitation module switch and the sampling module switch to close, and the grounding switch is disconnected; On the centralized control platform, select the detection unit at the end of the winding to be tested, set it to the response unit state, and send instructions; the main control CPU of the detection unit receives the instructions through the communication module, controls the excitation module switch to open, the sampling module switch and the grounding switch to close; S3. The excitation module of the detection unit in the excitation unit state outputs a sweep signal; S4. The control platform issues a signal acquisition instruction, and the main control CPU of the detection unit in the excitation unit state receives the instruction through the communication module. The communication module also sends a signal acquisition instruction to the detection unit in the response unit state for communication synchronization; the sampling modules of the two detection units synchronously collect voltage signals; S5. The sampling modules of the two detection units collect voltage amplitude signals at different frequencies and feed them back to their respective master CPUs; the master CPU of the detection unit in the response unit state collects the voltage amplitude signal and sends it to the detection unit in the excitation unit state via the communication module; S6. The main control CPU of the detection unit in the excitation unit state performs logarithmic division operation on the voltage amplitude of the response unit winding and the voltage amplitude of the excitation unit winding at the same frequency to obtain the amplitude-frequency response analysis data at a specific frequency, and the amplitude-frequency response analysis data after the operation is completed is sent to the centralized control platform through the communication module; S7. The communication module of the detection unit in the excitation unit state uploads the amplitude-frequency response analysis data to the centralized control platform at every set time interval. The centralized control platform draws the frequency response analysis curve of the current test winding according to the amplitude-frequency response analysis data; S9. After completing the frequency response analysis of the winding under test, the centralized control platform selects the detection units at the beginning and end of the winding under test, sets them to the suspended unit state, and sends a command. The main control CPU of the two detection units receives the command through the communication module, controls the excitation module switch and the sampling module switch to open, and the grounding switch to close. S10. The centralized control platform switches to the frequency response analysis of the next arbitrary winding, repeating S1-S9. Alternatively, a fully automated configuration scheme can be set up for all transformer windings, with the first and last terminals of each winding defined as the excitation and response terminals, and repeated testing. Clicking the "One-click measurement" parameter automatically detects the frequency response of all transformer windings.

[0014] The present invention solves the problems of traditional transformer winding frequency response analysis (FRA) methods, such as repeated manual wiring operations on site, low test efficiency, and proneness to errors. It improves test efficiency and test safety, reduces test costs, and enables remote testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The overall schematic diagram of the detection method; Figure 2 Schematic diagram of the detection unit structure. DETAILED DESCRIPTION

[0016] A method for detecting the frequency response of a power transformer winding deformation, such as Figure 1 As shown, a detection unit 1 is installed at the outlet of each winding of the transformer under test. For transformers where the bushing leads cannot be removed, the detection unit is installed at the bushing terminal tap. Each detection unit can act as both an excitation unit to emit signals and a response unit to collect signals. All detection units are connected to the centralized control platform 2 through network communication, and are connected to each other through network communication. The housings of all detection units are grounded.

[0017] like Figure 2 As shown, all detection units have the same structure, including a main control CPU 11 , a communication module 12 , an excitation module 13 , a sampling module 14 , an excitation module switch K1 , a sampling module switch K2 , a grounding switch K3 and a detection port 15 .

[0018] The communication module 12 , the excitation module 13 , and the sampling module 14 are connected to the main control CPU 11 .

[0019] The main control CPU is used to receive instructions from the centralized control platform and control the excitation module 13, sampling module 14, excitation module switch K1, sampling module switch K2, and grounding switch K3 of this detection unit.

[0020] The communication module is used for communication between the detection unit and the centralized control platform, as well as with other detection units.

[0021] The excitation module 13 and the sampling module 14 are the excitation module and the sampling module in the frequency response tester.

[0022] The excitation module executes the main CPU instructions to generate a sweep frequency signal. The signal output terminal of the excitation module is connected to the detection port 15 through the excitation module switch K1. The excitation module switch K1 is a relay or IGBT switch. When the excitation module sends a sweep frequency signal, the excitation module switch K1 is closed and opened at other times.

[0023] The sampling module executes instructions from the main control CPU to sample the voltage signal. The sampling module's signal input is connected to detection port 15 via sampling module switch K2 and grounded via matching resistor R and ground switch K3. Sampling module switch K2 is a relay or IGBT switch. When the sampling module is sampling, sampling module switch K2 is closed and open at other times.

[0024] The detection port 15 is connected to the output terminal of the winding.

[0025] Each detection unit can function as an excitation unit, a response unit, or a suspended unit. The main control CPU switches between the three units by controlling the on / off switching of the excitation module switch K1, the sampling module switch K2, and the grounding switch K3: when the excitation module switch K1 and the sampling module switch K2 are closed and the grounding switch K3 is open, the unit functions as an excitation unit; when the excitation module switch K1 is open and the sampling module switch K2 and the grounding switch K3 are closed, the unit functions as a response unit; and when the excitation module switch K1 and the sampling module switch K2 are open and the grounding switch K3 is closed, the unit functions as a suspended unit.

[0026] The excitation module sends a sweep frequency signal to the transformer winding under test; the sampling module collects the voltage signal generated by the frequency response; the communication modules of each detection unit establish network communication, responsible for connecting the main control CPU of each detection unit and each detection unit to each other; the main control CPU executes the signals received by the communication module. The excitation module switch K1 controls the connection between the excitation module sweep frequency signal and the detection port; the sampling module switch K2 controls the connection between the voltage signal detected by the detection port and the sampling module; and the grounding switch K3 controls whether the sampling module circuit is grounded through a 50Ω matching resistor.

[0027] The centralized control platform realizes the control and data processing of the test process. The centralized control platform has the function of setting the detection unit to the "excitation unit" or "response unit" state. The detection unit of any winding can be set to any state according to the test needs. The centralized control platform sends a signal to the communication module of the specified detection unit that the detection unit under test is an excitation unit or a response unit. At the same time, the centralized control platform has a "one-button measurement" function, which can set a deformation frequency response test plan for the tested winding, that is, define the first and last outgoing terminals of a certain winding as the excitation terminal and the response terminal respectively, measure the reference voltage of the excitation unit at the first end and the response voltage of the response unit at the tail end of the tested winding, and complete the frequency response test of a winding. The centralized control platform can also set a configurable fully automatic detection plan according to the connection method of the transformer under test, define the first and last outgoing terminals of all windings as excitation units and response units respectively, and measure the reference voltage of the excitation unit at the first end and the response voltage of the response unit at the tail end of all tested windings in turn, thereby realizing automatic detection of the frequency response of all windings of the transformer.

[0028] Taking the frequency response test of all windings of three-phase transformer, high, medium and low voltage as an example, the specific detection method is described in detail, such as Figure 1 and 2 : Step (1) performs a frequency response test on all windings of the three-phase transformer, high, medium and low voltage. Detection units 1 are arranged at the output terminals of the transformer's high voltage windings, phases A, B, C, and N, the output terminals of the medium voltage windings, phases Am, Bm, Cm, and Nm, and the output terminals of the low voltage windings, phases a, b, and c. Each detection unit is initially in a suspended unit state, emitting no excitation signal and collecting no signal. The housings of all detection units are grounded.

[0029] Step (2) On the centralized control platform 2, any winding outlet detection unit in the high-voltage winding of the three-phase winding transformer is set as an excitation unit, and any other winding outlet detection unit in the high-voltage winding can be set as a response unit. Similarly, the low-voltage winding and medium-voltage winding detection units can also be set accordingly. For example, when testing the high-voltage winding, if the high-voltage N-phase winding outlet detection unit is set as an excitation unit, then any detection unit in the remaining high-voltage A / B / C phase windings can be set as a response unit; when testing the medium-voltage winding, if the medium-voltage Nm-phase winding outlet detection unit is set as an excitation unit, then any detection unit in the remaining medium-voltage Am / Bm / Cm phase windings can be set as a response unit; when testing the low-voltage winding, if the low-voltage a-phase winding outlet detection unit is set as an excitation unit, then any detection unit in the remaining medium-voltage b / c phase windings can be set as a response unit. The following describes the specific process by taking the high-voltage N-phase winding outlet terminal detection unit as the excitation unit and the high-voltage A-phase winding outlet terminal detection unit as the response unit as an example.

[0030] Step (3) The centralized control platform selects the high-voltage N-phase winding detection unit as the excitation unit, selects the high-voltage A-phase winding detection unit as the response unit, and sends instructions to the communication modules of the excitation unit and the response unit; the detection units of the remaining high-voltage B / C-phase windings, medium-voltage Am / Bm / Cm / Nm-phase windings, and low-voltage a / b / c-phase winding output terminals maintain the initial suspended unit state.

[0031] In step (4), at the high-voltage N-phase winding outlet, the main control CPU in the detection unit, which serves as the excitation unit, receives instructions via the communication module to close the excitation module switch K1 and the sampling module switch K2, and to open the grounding switch K3. At the high-voltage A-phase winding outlet, the main control CPU in the detection unit, which serves as the response unit, receives instructions via the communication module to open the excitation module switch K1, and to close the sampling module switch K2 and the grounding switch K3. The communication modules of each detection unit use the LoRa mode for networking communication, responsible for connecting the main control CPU of each detection unit and the network communication between each detection unit.

[0032] In step (5), the excitation module of the detection unit whose output terminal of the high-voltage N-phase winding is in the excitation unit state outputs a sweep frequency excitation signal.

[0033] In step (6), the centralized control platform issues a signal acquisition instruction, and the main control CPU of the detection unit whose high-voltage N-phase winding output terminal is in the excitation unit state receives the instruction through the communication module. The communication module simultaneously sends the signal acquisition instruction to the detection unit whose high-voltage A-phase winding output terminal is in the response unit state to perform communication synchronization; the sampling modules of the two detection units synchronously acquire voltage signals.

[0034] In step (7), the sampling modules of the two detection units feed back the collected voltage amplitude signals at different frequencies to their respective main control CPUs; the main control CPU of the detection unit whose high-voltage A-phase winding output terminal is in the response unit state sends the collected voltage amplitude signal to the detection unit whose high-voltage N-phase winding is in the excitation unit state through the communication module.

[0035] In step (8), the main control CPU of the detection unit in which the high-voltage N-phase winding terminal group is in the excitation unit state performs logarithmic division operation on the voltage amplitude of the high-voltage A-phase winding and the voltage amplitude of the high-voltage N-phase winding at the same frequency, thereby obtaining the amplitude-frequency response analysis data at a specific frequency, and then uploads the amplitude-frequency response analysis data after the operation to the communication module of the high-voltage N-phase winding excitation unit in real time.

[0036] In step (9), the communication module of the detection unit whose high-voltage N-phase winding outlet is in the excitation unit state uploads the amplitude-frequency response analysis data to the centralized control platform at set intervals (usually 1 second). The centralized control platform draws the frequency response analysis curve of the current test winding based on the amplitude-frequency response analysis data.

[0037] After the frequency response analysis test of the high-voltage A-phase winding is completed in step (10), the high-voltage A-phase winding outlet terminal and the high-voltage N-phase winding outlet terminal detection unit are selected on the centralized control platform, set to a suspended unit state, and send instructions; the main control CPU of the two detection units receives the instructions through the communication module, controls the excitation module switch K1 and the sampling module switch K2 to be disconnected, and the grounding switch K3 to be closed; Step (11) Switch to the frequency response analysis of the next arbitrary winding on the PC-side centralized control platform and repeat steps (1) to (10).

[0038] Step (12) If you want to perform a "one-click measurement" of the frequency response of all windings of the transformer as a whole, you can also set a configuration scheme for the transformer winding as a whole, and define the first and last output ends of each winding as the excitation end and the response end respectively, and test them in sequence. For example, in the first group, the high-voltage N-phase winding detection unit is set as the excitation unit, and the high-voltage A-phase detection unit is set as the response unit; in the second group, the high-voltage N-phase detection unit is set as the excitation unit, and the high-voltage B-phase detection unit is set as the response unit; in the third group, the low-voltage a-phase detection unit is set as the excitation unit, and the low-voltage b-phase winding is set as the response unit... Click the "one-click measurement" parameter on the centralized control platform to automatically complete the frequency response detection of the first group, the second group, the third group, and up to the Nth group, thereby realizing automatic detection of the frequency response of all windings of the transformer.

Claims

1. A method for detecting the frequency response of a power transformer winding deformation, characterized by: A detection unit is installed at the outgoing end of each winding of the transformer to be tested. For transformers where the bushing lead cannot be removed, the detection unit is installed on the tap of the bushing end screen. All detection units are connected to the centralized control platform through network communication, and the detection units are connected to each other through network communication. All detection units have the same structure, including a main control CPU, a communication module, an excitation module, a sampling module, an excitation module switch, a sampling module switch, a grounding switch, and a detection port; the communication module, the excitation module, and the sampling module are connected to the main control CPU; the main control CPU is used to receive instructions from the centralized control platform and control the excitation module, sampling module, excitation module switch, sampling module switch, and grounding switch of the detection unit; The communication module is used for communication between the detection unit and the centralized control platform, as well as with other detection units; The excitation module executes the main control CPU instruction to generate a frequency sweep signal, and the signal output end of the excitation module is connected to the detection port through the excitation module switch; The sampling module executes the main control CPU instruction to sample the voltage signal. The signal input end of the sampling module is connected to the detection port through the sampling module switch and is grounded through the matching resistor and the grounding switch. The detection port is connected to the output terminal of the winding; The centralized control platform realizes the control and data processing of the test process. The centralized control platform sets the detection unit as an excitation unit or a response unit, and sets the detection unit of any winding to any state according to the test requirements; the centralized control platform sends a signal that the tested detection unit is an excitation unit or a response unit to the communication module of the specified detection unit, and sets a deformation frequency response test scheme for the tested winding, that is, the head and tail outgoing ends of a certain winding are defined as the excitation end and the response end, respectively, and the reference voltage of the excitation unit at the head end and the response voltage of the response unit at the tail end of the tested winding are measured to complete the frequency response test of a winding; the centralized control platform sets a configured fully automatic detection scheme according to the connection mode of the tested transformer, defines the detection units at the head and tail outgoing ends of all windings as excitation units and response units, respectively, and measures the reference voltage of the excitation unit at the head end and the response voltage of the response unit at the tail end of all tested windings in turn, thereby realizing automatic detection of the frequency response of all windings of the transformer.

2. The method for detecting frequency response of a power transformer winding deformation according to claim 1, wherein: Each detection unit acts as an excitation unit, a response unit or a suspended unit. The main control CPU realizes the switching of the three state units by controlling the closing and opening of the excitation module switch, the sampling module switch and the grounding switch: when the excitation module switch and the sampling module switch are closed and the grounding switch is disconnected, the detection unit is an excitation unit; when the excitation module switch is disconnected and the sampling module switch and the grounding switch are closed, the detection unit is a response unit; when the excitation module switch and the sampling module switch are disconnected and the grounding switch is closed, the detection unit is a suspended unit.

3. The method for detecting frequency response of a power transformer winding deformation according to claim 1, wherein: The excitation module switch is a relay or an IGBT switch. When the excitation module sends a sweep frequency signal, the excitation module switch is closed and disconnected at other times. The sampling module switch is a relay or an IGBT switch. When the sampling module performs sampling, the sampling module switch is closed and disconnected at other times.

4. A method for detecting frequency response of a power transformer winding deformation according to claim 3, characterized in that: The specific detection methods are as follows: S1. Detection units are placed at the output terminals of all high-, medium-, and low-voltage windings of the transformer. The housing of each detection unit is grounded, and all detection units are initially in the suspended unit state. S2. Select the detection unit of the first end of the winding under test on the centralized control platform, set it to the excitation unit state, and send a command; the main control CPU of the detection unit receives the command through the communication module, controls the excitation module switch and the sampling module switch to close, and the grounding switch is disconnected; On the centralized control platform, select the detection unit at the end of the winding to be tested, set it to the response unit state, and send instructions; the main control CPU of the detection unit receives the instructions through the communication module, controls the excitation module switch to open, the sampling module switch and the grounding switch to close; S3. The excitation module of the detection unit in the excitation unit state outputs a sweep signal; S4. The control platform issues a signal acquisition instruction, and the main control CPU of the detection unit in the excitation unit state receives the instruction through the communication module. The communication module also sends a signal acquisition instruction to the detection unit in the response unit state for communication synchronization; the sampling modules of the two detection units synchronously collect voltage signals; S5. The sampling modules of the two detection units collect voltage amplitude signals at different frequencies and feed them back to their respective master CPUs; the master CPU of the detection unit in the response unit state collects the voltage amplitude signal and sends it to the detection unit in the excitation unit state via the communication module; S6. The main control CPU of the detection unit in the excitation unit state performs logarithmic division operation on the voltage amplitude of the response unit winding and the voltage amplitude of the excitation unit winding at the same frequency to obtain the amplitude-frequency response analysis data at a specific frequency, and the amplitude-frequency response analysis data after the operation is completed is sent to the centralized control platform through the communication module; S7. The communication module of the detection unit in the excitation unit state uploads the amplitude-frequency response analysis data to the centralized control platform at every set time interval. The centralized control platform draws the frequency response analysis curve of the current test winding according to the amplitude-frequency response analysis data; S9. After completing the frequency response analysis of the winding under test, the centralized control platform selects the detection units at the beginning and end of the winding under test, sets them to the suspended unit state, and sends a command. The main control CPU of the two detection units receives the command through the communication module, controls the excitation module switch and the sampling module switch to open, and the grounding switch to close. S10. The centralized control platform switches to the next arbitrary winding for frequency response analysis and repeats S1-S9.

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