Online detection device and method for leakage current of oil-immersed current transformer
By using large and small diameter non-contact perforated current sensors in oil-immersed current transformers to detect leakage current signals and perform signal corrections, the problem of detection difficulty in the prior art is solved, and accurate and efficient leakage is achieved Current detection.
Patent Information
- Application Number
- CN202411714155.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-27
- Publication Date
- 2025-02-21
AI Technical Summary
The prior art is difficult to accurately detect leakage current signals of oil-immersed current transformers, especially due to the large diameter of the frame rod, which increases the detection difficulty.
A large-diameter non-contact perforation current sensor is used to detect the leakage current signal of the frame rod circuit, and a small-diameter non-contact perforation current sensor is used to detect the leakage current signal of the secondary tube circuit. After the correction signal is reached in the same phase, the amplitude is adjusted. Add values to obtain leakage current.
Accurate online detection of leakage current of oil-immersed current transformer is achieved, reducing the workload of on-site staff and improving detection efficiency.
Smart Images
Figure CN119492966A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of transformer detection, and in particular to an online detection device and method for leakage current of an oil-immersed current transformer. Background Art
[0002] Current transformer is one of the important equipment in power system, and its safety and reliability will directly affect the stable operation of power plants, substations and even power grids. Oil-immersed current transformer is the most widely used in my country's power system, and the detection of its leakage current is one of the important methods to judge its insulation status.
[0003] The leakage current of the oil-immersed current transformer has two circuits: the frame rod and the secondary tube. It is a tiny signal at the milliampere level, usually in the range of 50mA~150mA, and is not easy to collect. The diameter of the frame rod of the oil-immersed current transformer is relatively large, usually reaching tens of centimeters, and the caliber size of the detection unit is relatively high. Summary of the invention
[0004] In view of the deficiencies in the prior art, the present invention provides an online detection device and method for leakage current of an oil-immersed current transformer. For a frame rod with a larger diameter, a large-caliber non-contact perforated current sensor is used to detect the leakage current signal of the frame rod loop, and a small-caliber non-contact perforated current sensor is used to detect the leakage current signal of the secondary pipe loop. After correcting the two leakage current signals to the same phase, the leakage current amplitudes are added to obtain the leakage current of the measured current transformer.
[0005] To achieve the above object, the present invention adopts the following technical solutions: An online detection device for leakage current of an oil-immersed current transformer, comprising: A sampling unit, used for detecting leakage current signals in real time; A control processing unit is used to amplify, filter and convert the leakage current signal into analog-to-digital form, and then calculate the amplitude, phase and phase difference of the leakage current; and transmit the amplitude, phase and phase difference of the leakage current to a background terminal unit through a channel; The back-end terminal unit is used to calculate the actual leakage current of the current transformer under test based on the amplitude, phase and phase difference of the leakage current.
[0006] To optimize the above technical solutions, the specific measures taken also include: Furthermore, the sampling unit includes a sampling circuit A and a sampling circuit B, wherein the sampling circuit A detects a leakage current signal of a current transformer frame pole loop, and the sampling circuit B detects a leakage current signal of a current transformer secondary tube loop.
[0007] Further, the control processing unit includes: a signal conditioning circuit A, a signal conditioning circuit B, an A / D conversion circuit A, an A / D conversion circuit B and a CPU; The signal conditioning circuit A is used to amplify and filter the leakage current signal of the frame rod loop, and the signal conditioning circuit B is used to amplify and filter the leakage current signal of the secondary pipe loop; The A / D conversion circuit A is used to perform analog-to-digital conversion on the filtered leakage current signal of the frame rod loop to obtain a leakage current digital signal of the frame rod loop; the A / D conversion circuit B is used to perform analog-to-digital conversion on the filtered leakage current signal of the secondary tube loop to obtain a leakage current digital signal of the secondary tube loop; The CPU is used to implement FFT algorithm on the leakage current digital signal of the frame rod loop and the leakage current digital signal of the secondary pipe loop, respectively, to obtain the amplitude and phase of the leakage current digital signal of the frame rod loop and the leakage current digital signal of the secondary pipe loop, and to calculate the phase difference between the leakage current digital signal of the frame rod loop and the leakage current digital signal of the secondary pipe loop.
[0008] Furthermore, the control processing unit also includes a wired communication circuit and a wireless communication circuit, which are used to transmit the amplitude, phase and phase difference of the leakage current to the background terminal unit.
[0009] Furthermore, the detection device also includes a power supply unit for supplying power to the sampling unit and the control processing unit.
[0010] The present invention also provides an online detection method for leakage current of an oil-immersed current transformer, comprising the following steps: Real-time detection of leakage current signal; The leakage current signal is amplified, filtered and converted into analog-to-digital form, and then the amplitude, phase and phase difference of the leakage current are calculated; the amplitude, phase and phase difference of the leakage current are transmitted to the background terminal unit through the channel; In the background terminal unit, the actual leakage current of the current transformer under test is calculated based on the amplitude, phase and phase difference of the leakage current.
[0011] To optimize the above technical solutions, the specific measures taken also include: Furthermore, the leakage current signal includes a leakage current signal of a current transformer frame pole loop and a leakage current signal of a current transformer secondary tube loop.
[0012] Furthermore, the specific process of calculating the amplitude, phase and phase difference of the leakage current after amplifying, filtering and analog-to-digital conversion of the leakage current signal is as follows: Amplify and filter the leakage current signal of the frame rod loop, and amplify and filter the leakage current signal of the secondary pipe loop; Performing analog-to-digital conversion on the filtered leakage current signal of the frame rod loop to obtain a leakage current digital signal of the frame rod loop; performing analog-to-digital conversion on the filtered leakage current signal of the secondary pipe loop to obtain a leakage current digital signal of the secondary pipe loop; The FFT algorithm is implemented on the leakage current digital signal of the frame pole loop and the leakage current digital signal of the secondary pipe loop respectively to obtain the amplitude and phase of the leakage current digital signal of the frame pole loop and the leakage current digital signal of the secondary pipe loop respectively, and the phase difference between the leakage current digital signal of the frame pole loop and the leakage current digital signal of the secondary pipe loop is calculated.
[0013] Furthermore, the channel is a wired channel or a wireless channel.
[0014] Furthermore, the specific process of calculating the actual leakage current of the current transformer under test based on the amplitude, phase and phase difference of the leakage current is: According to the phase difference between the leakage current digital signal of the frame rod loop and the leakage current digital signal of the secondary tube loop, the phase of the leakage current digital signal of the frame rod loop and the phase of the leakage current digital signal of the secondary tube loop are corrected to be in phase; The actual leakage current of the current transformer under test is obtained by adding the amplitude of the leakage current digital signal of the frame pole loop after phase correction to the amplitude of the leakage current digital signal of the secondary tube loop.
[0015] The beneficial effects of the present invention are: The present invention adopts a non-contact online real-time detection method to detect the leakage current of the oil-immersed current transformer, which can not only accurately obtain the real-time leakage current value of the tested oil-immersed current transformer and discover the fault situation in time, but also reduce the workload of the staff on site and improve the work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 The present invention is a block diagram of the principle of the online leakage current detection device for oil-immersed current transformer.
[0017] Figure 2 The present invention is a flow chart of an online detection method for leakage current of an oil-immersed current transformer.
[0018] Figure 3 The present invention is a wiring diagram of an online leakage current detection device for an oil-immersed current transformer.
[0019] In the figure: 100, sampling unit; 101, sampling circuit A; 102, sampling circuit B; 200, control processing unit; 201, CPU; 202, A / D conversion circuit A; 203, A / D conversion circuit B; 204, signal conditioning circuit A; 205, signal conditioning circuit B; 206, wired communication circuit; 207, wireless communication circuit; 300, background terminal unit; 400, power supply unit; 401, power supply circuit A; 402, power supply circuit B. DETAILED DESCRIPTION
[0020] The present invention will now be described in further detail with reference to the accompanying drawings.
[0021] Embodiment 1
[0022] Reference Figure 1 and Figure 3 , which is the first embodiment of the present invention, provides an online detection device for leakage current of an oil-immersed current transformer, which can realize online detection of leakage current of an oil-immersed current transformer.
[0023] An online detection device for leakage current of an oil-immersed current transformer, comprising: The sampling unit 100 is used to detect leakage current signals in real time; the sampling unit 100 includes a sampling circuit A101 and a sampling circuit B102, the sampling circuit A101 detects leakage current signals of the current transformer frame pole loop, and the sampling circuit B102 detects leakage current signals of the current transformer secondary tube loop.
[0024] The control processing unit 200 is used to amplify, filter and convert the leakage current signal into analog-to-digital form to calculate the amplitude, phase and phase difference of the leakage current; and transmit the amplitude, phase and phase difference of the leakage current to the background terminal unit 300 through the channel.
[0025] The control processing unit 200 includes: a signal conditioning circuit A204, a signal conditioning circuit B205, an A / D conversion circuit A202, an A / D conversion circuit B203 and a CPU 201; The signal conditioning circuit A204 is used to amplify and filter the leakage current signal of the frame rod loop, and the signal conditioning circuit B205 is used to amplify and filter the leakage current signal of the secondary pipe loop; The A / D conversion circuit A202 is used to perform analog-to-digital conversion on the leakage current signal of the frame rod loop after filtering, so as to obtain a leakage current digital signal of the frame rod loop; the A / D conversion circuit B203 is used to perform analog-to-digital conversion on the leakage current signal of the secondary tube loop after filtering, so as to obtain a leakage current digital signal of the secondary tube loop; CPU201 is used to implement FFT algorithm on the leakage current digital signal of the frame pole loop and the leakage current digital signal of the secondary pipe loop, respectively, to obtain the amplitude and phase of the leakage current digital signal of the frame pole loop and the leakage current digital signal of the secondary pipe loop, and to calculate the phase difference between the leakage current digital signal of the frame pole loop and the leakage current digital signal of the secondary pipe loop.
[0026] The control processing unit 200 further includes a wired communication circuit 206 and a wireless communication circuit 207 for transmitting the amplitude, phase and phase difference of the leakage current to the background terminal unit 300 .
[0027] The background terminal unit 300 is used to calculate the actual leakage current of the current transformer under test based on the amplitude, phase and phase difference of the leakage current.
[0028] The detection device further includes a power supply unit 400 for supplying power to the sampling unit 100 and the control processing unit 200 .
[0029] When in use, the output end of the large-diameter perforated current sensor for collecting the leakage current signal of the current transformer frame rod is connected to the sampling circuit A101, and the output end of the small-diameter perforated current sensor for collecting the leakage current signal of the secondary tube of the current transformer is connected to the sampling circuit B102. The sampling circuit A101 detects the leakage current amplitude and phase characteristic signals in real time, and transmits the detected current amplitude and phase characteristic signals to the signal conditioning circuit A204; the signal conditioning circuit A204 amplifies and filters the current amplitude and phase characteristic signals, and the A / D conversion circuit A202 converts the current signal into a digital signal. After the digital signal is transmitted to the CPU201, the CPU201 calculates the amplitude, phase and phase difference of the leakage current signals of the frame rod loop and the secondary tube loop, and stores the results in the CPU201, and transmits them to the background terminal unit 300 through the wired communication circuit 206 or the wireless communication circuit 207. Finally, the background terminal unit 300 measures the leakage current of the current transformer.
[0030] Embodiment 2
[0031] Reference Figure 1~Figure 3 , which is the second embodiment of the present invention, and is based on the previous embodiment: This embodiment discloses an online detection method for leakage current of an oil-immersed current transformer, comprising the following steps: Real-time detection of leakage current signals; the leakage current signals include leakage current signals of the current transformer frame pole loop and leakage current signals of the current transformer secondary tube loop.
[0032] The leakage current signal is amplified, filtered and converted into analog to digital form to calculate the amplitude, phase and phase difference of the leakage current. The specific process is as follows: Amplify and filter the leakage current signal of the frame rod loop, and amplify and filter the leakage current signal of the secondary pipe loop; Performing analog-to-digital conversion on the filtered leakage current signal of the frame rod loop to obtain a leakage current digital signal of the frame rod loop; performing analog-to-digital conversion on the filtered leakage current signal of the secondary pipe loop to obtain a leakage current digital signal of the secondary pipe loop; The FFT algorithm is implemented on the leakage current digital signal of the frame pole loop and the leakage current digital signal of the secondary pipe loop respectively to obtain the amplitude and phase of the leakage current digital signal of the frame pole loop and the leakage current digital signal of the secondary pipe loop respectively, and the phase difference between the leakage current digital signal of the frame pole loop and the leakage current digital signal of the secondary pipe loop is calculated.
[0033] The amplitude, phase and phase difference of the leakage current are transmitted to the background terminal unit through a channel; the channel is a wired channel or a wireless channel.
[0034] In the background terminal unit, the actual leakage current of the current transformer under test is calculated based on the amplitude, phase and phase difference of the leakage current. The specific process is: According to the phase difference between the leakage current digital signal of the frame rod loop and the leakage current digital signal of the secondary tube loop, the phase of the leakage current digital signal of the frame rod loop and the phase of the leakage current digital signal of the secondary tube loop are corrected to be in phase; The actual leakage current of the current transformer under test is obtained by adding the amplitude of the leakage current digital signal of the frame pole loop after phase correction to the amplitude of the leakage current digital signal of the secondary tube loop.
[0035] When in use, since the leakage current of the oil-immersed current transformer has two loops, the frame rod and the secondary tube, a large-diameter through-type current transformer is installed at the frame rod with a larger diameter, and a through-type current transformer is also installed on the secondary tube. The leakage current signals of the frame rod loop and the secondary tube loop are measured at the same time, and the measured leakage current signal of the frame rod loop is connected to the sampling circuit A101 and amplified and filtered by the signal conditioning circuit A204. The current signal after amplification and filtering is transmitted to the A / D conversion circuit A202, and the A / D conversion circuit A202 converts the electrical signal into a digital signal and transmits it to the CPU201, and the measured leakage current signal of the secondary tube loop is The sampling circuit B102 is connected and amplified and filtered by the signal conditioning circuit B205. The current signal after amplification and filtering is transmitted to the A / D conversion circuit B203. The A / D conversion circuit B203 converts the electrical signal into a digital signal and transmits it to the CPU201. The CPU201 calculates the amplitude, phase and phase difference of the two leakage current signals based on the FFT algorithm. The background terminal unit 300 corrects the two leakage current signals to the same phase according to the amplitude, phase and phase difference of the received frame rod leakage current signal and secondary tube leakage current signal, and then adds the leakage current amplitudes to obtain the leakage current of the measured current transformer.
[0036] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back", etc. cited in the invention are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.
[0037] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.
Claims
1. An online leakage current detection device for an oil-immersed current transformer, characterized in that: include: A sampling unit (100), used for detecting leakage current signals in real time; A control processing unit (200) is used to amplify, filter and perform analog-to-digital conversion on the leakage current signal and then calculate the amplitude, phase and phase difference of the leakage current; and transmit the amplitude, phase and phase difference of the leakage current to a background terminal unit (300) through a channel; The back-end terminal unit (300) is used to calculate the actual leakage current of the current transformer under test based on the amplitude, phase and phase difference of the leakage current.
2. The oil-immersed current transformer leakage current online detection device according to claim 1, characterized in that: The sampling unit (100) comprises a sampling circuit A (101) and a sampling circuit B (102), wherein the sampling circuit A (101) detects a leakage current signal of a current transformer frame pole loop, and the sampling circuit B (102) detects a leakage current signal of a current transformer secondary tube loop.
3. The oil-immersed current transformer leakage current online detection device according to claim 1, characterized in that: The control processing unit (200) comprises: a signal conditioning circuit A (204), a signal conditioning circuit B (205), an A / D conversion circuit A (202), an A / D conversion circuit B (203) and a CPU (201); The signal conditioning circuit A (204) is used to amplify and filter the leakage current signal of the frame rod loop, and the signal conditioning circuit B (205) is used to amplify and filter the leakage current signal of the secondary pipe loop; The A / D conversion circuit A (202) is used to perform analog-to-digital conversion on the filtered leakage current signal of the frame rod loop to obtain a leakage current digital signal of the frame rod loop; the A / D conversion circuit B (203) is used to perform analog-to-digital conversion on the filtered leakage current signal of the secondary pipe loop to obtain a leakage current digital signal of the secondary pipe loop; The CPU (201) is used to implement an FFT algorithm on the leakage current digital signal of the frame rod loop and the leakage current digital signal of the secondary pipe loop, respectively, to obtain the amplitude and phase of the leakage current digital signal of the frame rod loop and the leakage current digital signal of the secondary pipe loop, and to calculate the phase difference between the leakage current digital signal of the frame rod loop and the leakage current digital signal of the secondary pipe loop.
4. The oil-immersed current transformer leakage current online detection device according to claim 1, characterized in that: The control processing unit (200) further comprises a wired communication circuit (206) and a wireless communication circuit (207), which are used to transmit the amplitude, phase and phase difference of the leakage current to the background terminal unit (300).
5. The oil-immersed current transformer leakage current online detection device according to claim 1, characterized in that: The detection device further comprises a power supply unit (400) for supplying power to the sampling unit (100) and the control processing unit (200).
6. An online detection method for leakage current of an oil-immersed current transformer, characterized in that: The following steps are involved: Real-time detection of leakage current signal; The leakage current signal is amplified, filtered and converted into analog-to-digital form, and then the amplitude, phase and phase difference of the leakage current are calculated; the amplitude, phase and phase difference of the leakage current are transmitted to the background terminal unit through the channel; In the background terminal unit, the actual leakage current of the current transformer under test is calculated based on the amplitude, phase and phase difference of the leakage current.
7. The online detection method for leakage current of an oil-immersed current transformer according to claim 6, characterized in that: The leakage current signal includes a leakage current signal of a current transformer frame pole loop and a leakage current signal of a current transformer secondary tube loop.
8. The method for online detection of leakage current of an oil-immersed current transformer according to claim 7, characterized in that: The specific process of calculating the amplitude, phase and phase difference of the leakage current after amplifying, filtering and analog-to-digital conversion of the leakage current signal is as follows: Amplify and filter the leakage current signal of the frame rod loop, and amplify and filter the leakage current signal of the secondary pipe loop; Performing analog-to-digital conversion on the filtered leakage current signal of the frame rod loop to obtain a leakage current digital signal of the frame rod loop; performing analog-to-digital conversion on the filtered leakage current signal of the secondary pipe loop to obtain a leakage current digital signal of the secondary pipe loop; The FFT algorithm is implemented on the leakage current digital signal of the frame pole loop and the leakage current digital signal of the secondary pipe loop respectively to obtain the amplitude and phase of the leakage current digital signal of the frame pole loop and the leakage current digital signal of the secondary pipe loop respectively, and the phase difference between the leakage current digital signal of the frame pole loop and the leakage current digital signal of the secondary pipe loop is calculated.
9. The method for online detection of leakage current of an oil-immersed current transformer according to claim 6, characterized in that: The channel is a wired channel or a wireless channel.
10. The online detection method for leakage current of an oil-immersed current transformer according to claim 8, characterized in that: The specific process of calculating the actual leakage current of the current transformer under test based on the amplitude, phase and phase difference of the leakage current is as follows: According to the phase difference between the leakage current digital signal of the frame rod loop and the leakage current digital signal of the secondary tube loop, the phase of the leakage current digital signal of the frame rod loop and the phase of the leakage current digital signal of the secondary tube loop are corrected to be in phase; The actual leakage current of the current transformer under test is obtained by adding the amplitude of the leakage current digital signal of the frame pole loop after phase correction to the amplitude of the leakage current digital signal of the secondary tube loop.