A calibration method for partial discharge detection

Abstract

The present invention discloses a calibration method for partial discharge detection. Existing methods are not applicable to detection sites with strong electrical interference. In the method of the present invention, the pulse generator and the partial discharge detector agree on multiple pulse emission times. After the test specimen is powered off, the pulse generator emits calibration pulses with the same discharge amount at the agreed times. The partial discharge detector checks the pulses at the agreed times and uses the pulses with the same amplitude among the multiple pulses at the agreed times as the calibration reference. After the test specimen is powered on, the partial discharge detector performs partial discharge detection on the test specimen according to the calibration reference. In the method of the present invention, the pulse generator emits multiple pulses, which can increase the probability of avoiding interference signals and reduce the influence of interference signals on the standard pulse signal, and is applicable to detection sites with strong electrical interference.

Description

Technical Field

[0001] The present invention belongs to the technical field of power equipment detection, and particularly relates to a calibration method for partial discharge detection. Background Art

[0002] Excellent insulation performance is a basic condition for the normal operation of high-voltage equipment and even the power grid system. Insulation deterioration or insulation capacity failure is one of the main reasons for the failures of high-voltage power equipment and the power grid system. Using the detection of partial discharge characteristics to reflect the insulation state of high-voltage power equipment has been recognized as one of the most sensitive and effective means in the industry.

[0003] The pulse current method is one of the most widely used partial discharge detection methods. In the partial discharge detection based on the pulse current method, it is necessary to calibrate the measured value of the detection system with a pulse generator at the detection site, that is, a standard pulse with a matching magnitude is injected by the pulse generator for calibration, so as to determine the discharge amplitude of the test object. For example Figure 1 , the coupling capacitor C k and the impedance Z are connected in series and then connected in parallel with the pulse generator D and the test specimen C x . The test specimen C x is the high-voltage power equipment to be detected (such as transformers, instrument transformers, GIS, etc.). The partial discharge detector M is connected to the output end of the impedance Z and is used to measure and display the output voltage of the impedance. Specifically: one end of the coupling capacitor C k is connected to the high-voltage end of the pulse generator D and the high-voltage side of the test specimen C x . The other end of the coupling capacitor C k is connected to the input end of the impedance Z. The grounding end of the impedance Z, the common end of the pulse generator D and the low-voltage side of the test specimen C x are connected and grounded after being connected. The output end of the impedance Z is connected to the input end of the partial discharge detector M through a test line with a core wire. During detection, first, the high-voltage power equipment is powered off, and then the pulse generator D injects a standard pulse with a matching magnitude. The partial discharge detector M records the detection value corresponding to the standard pulse, and the ratio of the discharge amount of the standard pulse to the detection value is used as the calibration coefficient. Then, the high-voltage power equipment is powered on, and the detection value of the partial discharge detector M is recorded. According to the calibration coefficient, the partial discharge amount is obtained.

[0004] The current partial discharge detection method is applicable to the detection site with low electrical interference. However, in the detection site with high electrical interference, that is, when the interference signal is greater than the standard pulse signal, the calibration pulse will be affected by the interference signal, greatly reducing the accuracy of on-site calibration. The pulse generator D injects calibration pulses X2 and X4 with matching magnitudes at the calibration points, and the corresponding discharge quantity spectrograms are viewed on the partial discharge detector M. For example, four pulses, namely X1 to X4, are viewed on the partial discharge detector M. According to the pulse shapes, it can be determined whether each pulse is a standard pulse or an interference pulse. For example, according to the pulse shapes, it is determined that X1 and X3 are interference signals, and X2 and X4 are the standard pulses emitted by the pulse generator D. The amplitudes of pulses X1 to X4 are H1 to H4 respectively. If the amplitude H1 or H3 is the largest, according to the current calibration method, the pulse with the largest amplitude is defaulted as the standard pulse by default. Then, the interference signal X1 or X3 is misidentified as the standard pulse, while the true calibration pulses X2 and X4 are submerged by the interference signals X1 or X3. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a calibration method for partial discharge detection, which can solve the problem that the existing method is not applicable to the detection site with large electrical interference.

[0006] The method of the present invention connects the coupling capacitor C k in series with the impedance Z and then connects them in parallel with the pulse generator D and the test specimen C x ; the test specimen C x is the high-voltage power equipment to be detected; the partial discharge detector M is connected to the output end of the impedance Z for measuring and displaying the output voltage of the impedance. The pulse generator D and the partial discharge detector M are internally provided with satellite timing modules. The pulse generator D marks the time of the sent calibration pulse through the satellite timing module, and the partial discharge detector M views the pulse signal at the corresponding moment according to the time mark. The satellite timing module adopts a Beidou or GPS satellite timing module.

[0007] The specific calibration method is as follows:

[0008] Step (1) The pulse generator D and the partial discharge detector M agree on multiple pulse emission times T1, T2,..., T N ; where T n is the emission time of the nth pulse (n = 1, 2,..., N), and N is the number of pulses agreed to be emitted by the pulse generator D and the partial discharge detector M;

[0009] Step (2) The test specimen C x is powered off;

[0010] Step (3) At the agreed times T1, T2,..., T N , the pulse generator D emits calibration pulses with the same discharge quantity;

[0011] Step (4): The partial discharge detector M receives the pulses and checks the pulses at the agreed-upon times T1, T2, …, T N .

[0012] Step (5): The partial discharge detector M uses the pulses with the same amplitude among the N pulses at the agreed-upon times as the calibration reference;

[0013] Step (6): The test specimen C to be tested x is powered on;

[0014] Step (7): According to the calibration reference, the partial discharge detector M performs partial discharge detection on the test specimen C x .

[0015] The present invention can be applied to a detection site with strong electrical interference. By means of GPS or Beidou time-based synchronization, the time of the pulse generator and the partial discharge detector is kept synchronized. At the same time, the pulse generator and the partial discharge detector agree on the pulse sending time, so that the partial discharge detector can obtain the accurate time when the pulse is emitted, thereby improving the accuracy of obtaining the standard pulse. In addition, the pulse generator emits multiple pulses, which can increase the probability of avoiding interference signals, thereby reducing the influence of interference signals on the standard pulse signal. Description of the Drawings

[0016] Figure 1 is the schematic diagram of the partial discharge detection method of the present invention. Detailed Embodiment

[0017] The present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the described embodiments are only for facilitating the understanding of the present invention and do not impose any limitation on it.

[0018] A calibration method for partial discharge detection, as Figure 1 shown, connects the coupling capacitor C k and the impedance Z in series and then connects them in parallel with the pulse generator D and the test specimen C to be tested x . The test specimen C to be tested x is a high-voltage power equipment to be detected. The partial discharge detector M is connected to the output end of the impedance Z and is used to measure and display the output voltage of the impedance. Specifically: One end of the coupling capacitor C k is connected to the high-voltage end of the pulse generator D and the high-voltage side of the test specimen C to be tested x . The other end of the coupling capacitor C k is connected to the input end of the impedance Z. The grounding end of the impedance Z, the common end of the pulse generator D, and the test specimen C to be tested xThe low-voltage side is connected and grounded. The output end of the impedance Z and the input end of the partial discharge detector M are connected through a test line with a core wire. The pulse generator D and the partial discharge detector M are built-in with Beidou or GPS satellite timing modules. The pulse generator D uses the satellite timing module to time-stamp the sent calibration pulses, and the partial discharge detector M views the pulse signals at the corresponding moments according to the time stamps.

[0019] The specific calibration method is as follows:

[0020] Step (1) The pulse generator D and the partial discharge detector M agree on multiple pulse emission times T1, T2, …, T N ; where T n is the emission time of the nth pulse (n = 1, 2, …, N), and N is the number of pulses agreed to be emitted by the pulse generator D and the partial discharge detector M;

[0021] Step (2) The test article C to be tested x is powered off;

[0022] Step (3) At the agreed times T1, T2, …, T N , the pulse generator D emits calibration pulses with the same discharge amount;

[0023] Step (4) The partial discharge detector M receives the pulses and views the pulses at the agreed times T1, T2, …, T N ;

[0024] Step (5) The partial discharge detector M takes the pulses with the same amplitude among the N pulses at the agreed times as the calibration reference;

[0025] Step (6) The test article C to be tested x is powered on;

[0026] Step (7) According to the calibration reference, the partial discharge detector M performs partial discharge detection on the test article C x .

[0027] The pulse generator D agrees with the partial discharge detector M on multiple pulse emission times. For example, a standard pulse is sent at 2 ms, 3 ms, 5 ms, 7 ms, 9 ms, and 10 ms respectively. Then the partial discharge detector M knows that standard pulses will be received at 2 ms, 3 ms, 5 ms, 7 ms, 9 ms, and 10 ms. The partial discharge detector M detects 8 pulses, namely Y1 to Y8. The amplitudes of the pulses Y1 to Y8 are h1 to h8 respectively. Among them, the amplitude h1 of the pulse Y1 is the largest, but the reception time of the pulse Y1 is 1 ms, and the reception time of the pulse Y8 is 12 ms, which does not belong to the agreed time range. The pulses Y2 to Y7 are found according to the agreed pulse emission times. At the same time, the amplitudes of the pulses Y2, Y4, and Y6 are equal, h2 = h4 = h6. Then, it is determined that the pulses Y2, Y4, and Y6 are the standard pulses emitted by the pulse generator D, and the pulses Y2, Y4, and Y6 are selected as the calibration reference.

[0028] Through the partial discharge calibration method of the present invention, even in a test environment with strong interference signals, the partial discharge detector M can find the corresponding standard pulses through the agreed time range and select the standard pulses with the same amplitude as the calibration reference, thereby reducing the influence of the interference signals on the standard pulse signals and improving the accuracy of calibration.

Claims

1. A calibration method for partial discharge detection, in which a coupling capacitor C k and an impedance Z are connected in series and then connected in parallel with a pulse generator D and a test specimen C x . A partial discharge detector M is connected to the output end of the impedance Z and is used to measure and display the output voltage of the impedance; the test specimen C x is a high-voltage power equipment to be detected; it is characterized in that: The described pulse generator D and partial discharge detector M are built-in with satellite timing modules. The pulse generator D uses the satellite timing module to time-stamp the transmitted calibration pulses, and the partial discharge detector M views the pulse signals at the corresponding moments according to the time stamps; The pulse generator D and the partial discharge detector M agree on multiple pulse emission times. The partial discharge detector finds the corresponding standard pulses within the agreed time range, selects the standard pulses with the same amplitude as the calibration reference, and excludes the interference signals with different amplitudes. The specific method is as follows: Step (1): The pulse generator D and the partial discharge detector M agree on multiple pulse emission times, T1, T2, …, T N ; where T n is the emission time of the nth pulse, n = 1, 2, …, N, and N is the number of pulses agreed upon by the pulse generator D and the partial discharge detector M for emission; Step (2) Specimen C to be tested x Power off; Step (3) At the agreed-upon times T1, T2, …, T N , the pulse generator D emits calibration pulses with the same discharge amount; Step (4): The partial discharge detector M receives the pulses and checks for the pulses at the agreed-upon times T1, T2, …, T N of the pulses; Step (5): The partial discharge detector M uses the pulses with the same amplitude among the N pulses at the agreed moments as the calibration reference; Step (6) Specimen C to be tested x Apply power; Step (7) According to the calibration reference, the partial discharge detector M performs partial discharge detection on the test sample C x for partial discharge detection.

2. The calibration method for partial discharge detection according to claim 1, characterized in that: The described satellite timing module uses a Beidou or GPS satellite timing module.

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