An AC / DC withstand voltage partial discharge test system based on rectangular time-frequency filter

Abstract

The present invention relates to an AC / DC withstand voltage partial discharge test system based on a rectangular time-frequency filter, comprising a partial discharge ultra-wideband detection system, an AC withstand voltage test module, a DC withstand voltage test module, a two-dimensional time-frequency window dynamic display module, a rectangular time-frequency filter algorithm module, and a withstand voltage partial discharge data dynamic display and storage module; the partial discharge ultra-wideband detection system is respectively connected to the AC withstand voltage test module, the DC withstand voltage test module, and the two-dimensional time-frequency window dynamic display module, the two-dimensional time-frequency window dynamic display module is respectively connected to the rectangular time-frequency filter algorithm module and the withstand voltage partial discharge data dynamic display and storage module, and the rectangular time-frequency filter algorithm module is connected to the withstand voltage partial discharge data dynamic display and storage module. Compared with the prior art, the present invention has the advantages of better anti-interference effect and the like.

Description

Technical Field

[0001] The invention relates to an AC / DC withstand voltage partial discharge test system, in particular to an AC / DC withstand voltage partial discharge test system based on a rectangular time-frequency filter. Background Art

[0002] After years of practice, a large number of scientific research and engineering technicians have proposed anti-interference measures as shown in Table 1 for possible interference sources during partial discharge (PD) testing based on the traditional pulse current method (see mainly the standard DL / T 417-2006 "Guidelines for Field Measurement of Partial Discharges of Power Equipment"). In general, the AC and DC withstand voltage PD tests of power equipment can be carried out smoothly in factory tests, i.e. laboratory conditions, using the conventional pulse current PD detection method (wideband or narrowband method, the detection frequency band is within 1MHz) recommended by the standard GB / T 7354-2018 "Partial Discharge Measurement of High Voltage Test Technology" and the anti-interference measures shown in Table 1. Taking the AC and DC withstand voltage PD test of the converter transformer as an example, the test circuit is as follows Figure 1 shown.

[0003] Table 1

[0004]

[0005]

[0006] However, for on-site handover and fault diagnosis tests, there are still working conditions where it is difficult to eliminate interference pulse signals under complex electromagnetic backgrounds. The anti-interference technology recommended by the standard is difficult to implement, and the existing PD detection system often cannot distinguish whether the pulse signal comes from the interference source or the pressurized PD source. This means that AC and DC withstand voltage PD tests often require the experience of the test personnel to make judgments, which seriously affects the test process and there is a possibility of misjudgment. Summary of the invention

[0007] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide an AC / DC withstand voltage partial discharge test system based on a rectangular time-frequency filter.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] An AC / DC withstand voltage partial discharge test system based on a rectangular time-frequency filter, comprising a partial discharge ultra-wideband detection system, an AC withstand voltage test module, a DC withstand voltage test module, a two-dimensional time-frequency window dynamic display module, a rectangular time-frequency filter algorithm module, and a withstand voltage partial discharge data dynamic display and storage module;

[0010] The partial discharge ultra-wideband detection system is respectively connected to the AC withstand voltage test module, the DC withstand voltage test module and the two-dimensional time-frequency window dynamic display module, and the two-dimensional time-frequency window dynamic display module is respectively connected to the rectangular time-frequency filter algorithm module and the withstand voltage partial discharge data dynamic display and storage module, and the rectangular time-frequency filter algorithm module is connected to the withstand voltage partial discharge data dynamic display and storage module.

[0011] Preferably, the partial discharge ultra-wideband detection system comprises a broadband detection impedance, a signal conditioning unit, a data acquisition terminal, and an industrial control PC equipped with control and display software, which are connected in sequence;

[0012] In the partial discharge ultra-wideband detection system under the AC withstand voltage test module, the data acquisition terminal records the corresponding pulse group, which is a pulse waveform-phase time sequence.

[0013] Preferably, the partial discharge ultra-wideband detection system comprises a broadband detection impedance, a signal conditioning unit, a high-speed oscilloscope, and a laptop computer equipped with control and display software, which are connected in sequence;

[0014] In the partial discharge ultra-wideband detection system, under the DC withstand voltage test module, the high-speed oscilloscope records the corresponding pulse group, which is a pulse waveform-time sequence.

[0015] Preferably, the sampling rate of the data acquisition terminal or high-speed oscilloscope recording device needs to be 100MS / s or above, the analog bandwidth needs to be 50MHz or above, and the recorded and stored pulse waveform-time series is defined as follows:

[0016] Pulse ii (p ii (i),t ii ,U ii ),ii=1,2,…,N; i=1,2,…,k (1)

[0017] Where: ii is the iith pulse; N is the pulse current waveform p ii (i) The total number of; k is each pulse current waveform p ii (i) The number of points, pulse waveform p ii (i) It consists of k points, U ii is the pulse current waveform p ii (i) The withstand voltage value applied to the test piece at the time of triggering.

[0018] Preferably, the AC withstand voltage test module adopts an AC withstand voltage test system, specifically a long-time induction withstand voltage PD test circuit in which the converter transformer applies pressure on the grid side, including a generator set G, a compensating reactor L, a voltage measuring device V, an intermediate transformer T and a test product.

[0019] Preferably, the DC withstand voltage test module adopts a DC withstand voltage test system, specifically a converter transformer DC external withstand voltage PD test circuit, including a DC generator ZF, a protective resistor, a voltage measuring device V and a test product.

[0020] Preferably, the specific processing process of the two-dimensional time-frequency window dynamic display module is as follows:

[0021] Step 101, time domain pulse data preprocessing, the specific preprocessing process is:

[0022] The pulse groups obtained by ultra-wideband detection are preprocessed as follows:

[0023]

[0024] Where: a i is the amplitude corresponding to the i-th point, Δt(i-1) is the time corresponding to the i-th point, and Δt is the sampling time interval;

[0025] Step 102: Discrete fast short-time Fourier transform of the pulse group waveform,

[0026] For all waveforms of the pulse group, ii (t ii ) is used for discrete short-time Fourier transform, and we can get:

[0027]

[0028] Where: w(im) is a window function with a length of m;

[0029] According to equations (2) and (3), p ii (t ii ) ii (f ii ) is processed as:

[0030]

[0031] M i is the DSTFT amplitude corresponding to the i-th point, Δf(i-1) is the frequency component corresponding to the i-th point;

[0032] Step 103: Dynamic display of the two-dimensional time-frequency window of the pulse group.

[0033] From equations (2) and (4), we can get the pulse waveform-time series, i.e. the two-dimensional time-frequency window (T, F) corresponding to the pulse group: jj for:

[0034]

[0035] Preferably, the specific processing process of the rectangular time-frequency filter algorithm module is as follows:

[0036] Step 201. According to the two-dimensional time-frequency window (T, F) of the pulse group jj Dynamic display, that is, determine the position P of the rectangular time-frequency filter according to the (T, F) parameter distribution of the pulses before and after the start of the withstand voltage test under actual working conditions i ;

[0037] Step 202. Use the mouse to move the cursor to position P on the two-dimensional time-frequency window software display control. i Set a rectangular time-frequency filter Filter(i) = (T1_i, F1_i), (T2_i, F2_i), (T3_i, F3_i), (T4_i, F4_i);

[0038] Step 203. Get all (T, F) in the current rectangular time-frequency filter Filter (i) jj Corresponding pulse waveform-waveform time series

[0039] Step 204. Dynamic display of partial discharge data based on withstand voltage and storage module display The corresponding parameters include pulse time and frequency domain waveforms, peak-phase sequence, number of pulses, and pulse maximum value;

[0040] Step 205. Dynamically display the parameter distribution in the two-dimensional time-frequency window and the correlation between the time-frequency filter Filter (i) If the working conditions change, remove the existing time-frequency filter Filter(i) and reset Step 202.

[0041] Preferably, the pulse distribution that has appeared before the voltage is applied is the noise source, and a rectangular time-frequency filter Filter (1) can be set to observe its characteristics;

[0042] Similarly, the pulse distribution that appears after the voltage is applied is a PD source, and a rectangular time-frequency filter Filter (2) can be set again.

[0043] Preferably, the withstand voltage partial discharge data dynamic display and storage module stores all waveforms of the pulse group in real time, and displays corresponding parameters including pulse time domain and frequency domain waveforms, peak-phase sequence, number of pulses, and pulse maximum value.

[0044] Compared with the prior art, the present invention has the following advantages:

[0045] 1. The present invention manually sets a rectangular time-frequency filter on a two-dimensional time-frequency window, i.e., a time-frequency windowing method combining time domain and frequency domain, and dynamically displays the PD parameters under the current withstand voltage working condition associated with the rectangular time-frequency filter, thereby realizing the real-time anti-interference and pulse source separation technology combined in the time domain and frequency domain under the withstand voltage working condition. It has a better anti-interference effect than the existing system or method that uses the frequency domain filter and the time domain windowing method alone.

[0046] 2. The present invention is simple and practical, and stores all the pulse waveform-phase (time) sequences under the working conditions before and after the withstand voltage. In addition to being able to judge in real time whether the insulation tolerance of the current test product meets the PD test requirements, playback analysis can also be carried out after the test is completed, namely, ① interference pulse source elimination, ② multiple PD source separation and ③ withstand voltage test PD data tracing are realized (the data file is a pulse waveform-phase (time) sequence), and according to ③ accumulated data, the comparison between the factory delivery, on-site handover acceptance and fault diagnostic test data of the same equipment can be realized, providing a basis for the technical analysis support evaluation of the asset life cycle of power equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Circuit diagram of long-time induction withstand voltage PD test for converter transformer on grid side;

[0048] Figure 2 Circuit diagram for the DC withstand voltage PD test of the converter transformer;

[0049] Figure 3 It is a structural schematic diagram of the present invention;

[0050] Figure 4 It is a schematic diagram of the dynamic display of the pulse group two-dimensional time-frequency window of the present invention;

[0051] Figure 5 It is a flow chart of the rectangular time-frequency filter algorithm of the present invention;

[0052] Figure 6(a) to Figure 6(d) 6(a) shows two time-frequency filters arranged randomly on a two-dimensional time-frequency window, and there are no pulse groups in both time-frequency filter 1 and time-frequency filter 2; FIG6(b) shows two time-frequency filters arranged on a two-dimensional time-frequency window, and time-frequency filter 1 is dynamically associated with a background noise source with disordered phase, and time-frequency filter 2 is free of pulse groups; FIG6(c) shows two time-frequency filters arranged on a two-dimensional time-frequency window, and time-frequency filter 1 is dynamically associated with a background noise source with disordered phase, and time-frequency filter 2 is dynamically associated with an ordered phase, i.e., a PD source concentrated at 90° and 270°; FIG6(d) shows two time-frequency filters arranged on a two-dimensional time-frequency window, and time-frequency filter 1 is dynamically associated with an ordered phase, i.e., a PD source concentrated at 90° and 270°, and time-frequency filter 2 is dynamically associated with an ordered phase, i.e., a PD source concentrated at 30° and 210°;

[0053] Among them, G is the generator set; L is the compensating inductor; T is the intermediate transformer; V is the voltage measuring device; a and b are the valve side winding line ends; C1 and C2 are the valve side high-voltage bushing capacitors; A and N are the grid side winding line ends; S is the high-voltage end of the voltage regulating winding; C3 and C4 are the grid side high-voltage bushing capacitors; Z is the detection impedance; PDE is the partial discharge tester; ZF is the DC generator; R1 and R2 are protection resistors. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0055] The present invention provides an AC / DC withstand voltage partial discharge test system based on a rectangular time-frequency filter. That is, using a PD ultra-wideband detection system, according to the requirements of AC and DC withstand voltage PD tests, a two-dimensional time-frequency window (T, F) composed of discrete short-time Fourier transform is set to dynamically associate and display the PD parameters under the current withstand voltage working condition, including pulse time domain and frequency domain waveforms, peak-phase (time) sequence (i.e., pulse group), number of pulses, pulse maximum value, etc.; the test personnel manually set a rectangular time-frequency filter on the two-dimensional time-frequency window, i.e., the so-called time-frequency windowing method combined with the time domain and frequency domain, to dynamically display the PD parameters under the current withstand voltage working condition associated with the rectangular time-frequency filter, thereby realizing real-time anti-interference and pulse source separation technology under the withstand voltage working condition. The system and method are simple and practical. They store all the pulse waveform-phase (time) sequences under the working conditions before and after the withstand voltage. In addition to being able to judge in real time whether the insulation tolerance of the current test product meets the PD test requirements, they can also perform playback analysis after the test, namely, achieving ① elimination of interference pulse sources, ② separation of multiple PD sources and ③ tracing of PD data of the withstand voltage test (the data file is a pulse waveform-phase (time) sequence). Moreover, based on the accumulated data in ③, comparison between the factory delivery, on-site handover acceptance and fault diagnostic test data of the same equipment can be achieved, providing a basis for the technical analysis support and evaluation of the asset life cycle of power equipment.

[0056] like Figure 3 As shown, an AC / DC withstand voltage partial discharge test system 1 based on a rectangular time-frequency filter comprises a partial discharge ultra-wideband detection system 10, an AC withstand voltage test module 11, a DC withstand voltage test module 12, a two-dimensional time-frequency window dynamic display module 13, a rectangular time-frequency filter algorithm module 14 and a withstand voltage partial discharge data dynamic display and storage module 15;

[0057] The partial discharge ultra-wideband detection system 10 is respectively connected to the AC withstand voltage test module 11, the DC withstand voltage test module 12 and the two-dimensional time-frequency window dynamic display module 13, and the two-dimensional time-frequency window dynamic display module 13 is respectively connected to the rectangular time-frequency filter algorithm module 14 and the withstand voltage partial discharge data dynamic display and storage module 15, and the rectangular time-frequency filter algorithm module 14 is connected to the withstand voltage partial discharge data dynamic display and storage module 15.

[0058] The local discharge ultra-wideband detection system 10 records a single time domain waveform and a pulse waveform-(phase) time sequence corresponding to the triggering moment, i.e., a pulse group, based on the pulse waveform triggering technology. Generally, the pulse group under AC withstand voltage is a pulse waveform-phase time sequence; the pulse group under DC withstand voltage is a pulse waveform-time sequence. The local discharge ultra-wideband detection system 10 includes a broadband detection impedance, a signal conditioning unit, a data acquisition terminal, and an industrial control PC equipped with control and display software connected in sequence; the local discharge ultra-wideband detection system 10 is under the AC withstand voltage test module 11, and the data acquisition terminal records the corresponding pulse group, which is a pulse waveform-phase time sequence.

[0059] Alternatively, the partial discharge ultra-wideband detection system 10 comprises a broadband detection impedance, a signal conditioning unit, a high-speed oscilloscope, and a laptop computer equipped with control and display software, which are connected in sequence; the partial discharge ultra-wideband detection system 10 is under the DC withstand voltage test module 12, and the high-speed oscilloscope records the corresponding pulse group, which is a pulse waveform-time series.

[0060] The sampling rate of the data acquisition terminal or high-speed oscilloscope recording device must be 100MS / s or above, the analog bandwidth must be 50MHz or above, and the recorded and stored pulse waveform-time series is defined as follows:

[0061] Pulse ii (p ii (i),t ii ,U ii ),ii=1,2,…,N; i=1,2,…,k (1)

[0062] Where: ii is the iith pulse; N is the pulse current waveform p ii (i) The total number of; k is each pulse current waveform p ii (i) The number of points, pulse waveform p ii (i) It consists of k points, which is proportional to the sampling rate in the same time width (100 points at 100MS / s and 40 points at 250MS / s for a duration of 1μs), U ii is the pulse current waveform p ii(i) The withstand voltage value applied to the test piece at the time of triggering, kV.

[0063] like Figure 1 As shown, the AC withstand voltage test module adopts an AC withstand voltage test system, specifically a long-time induction withstand voltage PD test circuit in which the converter transformer applies pressure on the grid side, including a generator set G, a compensating inductor L, a voltage measuring device V, an intermediate transformer T and a test product.

[0064] like Figure 2 As shown, the DC withstand voltage test module adopts a DC withstand voltage test system, specifically a converter transformer DC external withstand voltage PD test circuit, including a DC generator ZF, a protective resistor, a voltage measuring device V and a test product.

[0065] Preferably, the specific processing process of the two-dimensional time-frequency window dynamic display module is as follows:

[0066] Step 101, preprocessing of time domain pulse data, this step makes the pulse group current waveform (original signal) acquired by the acquisition device in the partial discharge ultra-wideband detection system form a pulse-time sequence with unified standards and easy to process. That is, in order to facilitate the rapid transformation of subsequent pulse groups, the pulse groups acquired by ultra-wideband detection are preprocessed as follows:

[0067]

[0068] Where: a i is the amplitude corresponding to the i-th point (mV or pC), Δt(i-1) is the time corresponding to the i-th point, Δt is the sampling time interval, and Δt = 10ns at 100MS / s.

[0069] Step 102: Discrete fast short-time Fourier transform of the pulse group waveform,

[0070] For all waveforms p of the pulse group ii (t ii ) is used for discrete short-time Fourier transform (DSTFT), and we can get:

[0071]

[0072] Where: w(i) and m – window function of length m (e.g. Hamming);

[0073] According to equations (2) and (3), p ii (t ii ) ii (f ii ) is processed as:

[0074]

[0075] M i is the DSTFT amplitude corresponding to the i-th point (mV or pC), Δf(i-1) is the frequency component corresponding to the i-th point (sampling rate f s = kΔf, Δf = 1 / Δt);

[0076] Step 103: Dynamic display of the two-dimensional time-frequency window of the pulse group, such as Figure 4 As shown;

[0077] From equations (2) and (4), we can get the pulse waveform-time series, i.e. the two-dimensional time-frequency window (T, F) corresponding to the pulse group: jj for:

[0078]

[0079] Figure 4 middle,

[0080]

[0081] The specific processing process of the rectangular time-frequency filter algorithm module is as follows:

[0082] Step 201. According to the two-dimensional time-frequency window (T, F) of the pulse group jj Dynamic display, that is, determine the position P of the rectangular time-frequency filter according to the (T, F) parameter distribution of the pulses before and after the start of the withstand voltage test under actual working conditions i ;

[0083] Step 202. Use the mouse to move the cursor to position P on the two-dimensional time-frequency window software display control. i Set a rectangular time-frequency filter Filter(i) = (T1_i, F1_i), (T2_i, F2_i), (T3_i, F3_i), (T4_i, F4_i);

[0084] Step 203. Get all (T, F) in the current rectangular time-frequency filter Filter (i) jj Corresponding pulse waveform-waveform time series

[0085] Step 204. Dynamic display of partial discharge data based on withstand voltage and storage module display The corresponding parameters include pulse time and frequency domain waveforms, peak-phase sequence, number of pulses, and pulse maximum value;

[0086] Step 205. Dynamically display the parameter distribution in the two-dimensional time-frequency window and the correlation between the time-frequency filter Filter (i) If the working conditions change, remove the existing time-frequency filter Filter(i) and reset Step 202.

[0087] Generally speaking, the pulse distribution that appears before the voltage is applied is a noise source. A rectangular time-frequency filter Filter (1) can be set to observe its characteristics. Based on the 15 withstand voltage partial discharge data dynamic display and storage module, the display includes the pulse time domain and frequency domain waveforms, peak-phase (time) sequence, number of pulses, pulse maximum value and other parameters. Similarly, the pulse distribution that appears after the voltage is applied is a PD source. A rectangular time-frequency filter Filter (2) can be set again. Based on the withstand voltage partial discharge data dynamic display and storage module, the display also includes the pulse time domain and frequency domain waveforms, peak-phase (time) sequence, number of pulses, pulse maximum value and other PD parameters.

[0088] The dynamic display and storage module of withstand voltage partial discharge data stores all waveforms of the pulse group in real time, and displays the corresponding parameters including pulse time domain and frequency domain waveforms, peak-phase (time) sequence, number of pulses, pulse maximum value, etc.

[0089] The partial discharge ultra-wideband detection system module collects the pulse waveform-phase (time) sequence, i.e., the pulse group, which contains the background noise source and the PD source generated by the test product under the AC withstand voltage test module or the DC withstand voltage test module; the two-dimensional time-frequency window dynamic display module performs discrete short-time Fourier transform (DSTFT) on the pulse group to form a two-dimensional time-frequency window, and provides (T, F) parameter distribution for the test personnel to manually set a rectangular time-frequency filter (rectangular time-frequency filter software module) on the two-dimensional time-frequency window, i.e., the so-called time-frequency joint windowing method; the withstand voltage partial discharge data dynamic display module dynamically correlates and displays the relevant parameters of the pulse group corresponding to the two-dimensional time-frequency window and the time-frequency filter under the current withstand voltage working condition according to the requirements of the AC and DC withstand voltage PD tests, including the pulse time domain and frequency domain waveforms, peak-phase (time) sequence, number of pulses, pulse maximum value, etc., so as to realize the real-time anti-interference and pulse source separation technology under the withstand voltage working condition.

[0090] Figure 6 shows an example of AC withstand voltage PD test application obtained by using 50MHz analog bandwidth and 250MS / s ultra-wideband detection. Figure 6(a) shows that two time-frequency filters are randomly arranged on the two-dimensional time-frequency window, and there is no pulse group in both time-frequency filter 1 and time-frequency filter 2; Figure 6(b) shows that two time-frequency filters are arranged on the two-dimensional time-frequency window, and time-frequency filter 1 is dynamically associated with a phase-disordered background noise source, and time-frequency filter 2 is free of pulse groups; Figure 6(c) shows that two time-frequency filters are arranged on the two-dimensional time-frequency window, and time-frequency filter 1 is dynamically associated with a phase-disordered background noise source, and time-frequency filter 2 is dynamically associated with a phase-ordered PD source, that is, concentrated at 90° and 270°; Figure 6(d) shows that two time-frequency filters are arranged on the two-dimensional time-frequency window, and time-frequency filter 1 is dynamically associated with a phase-ordered PD source, that is, concentrated at 90° and 270°, and time-frequency filter 2 is dynamically associated with a phase-ordered PD source, that is, concentrated at 30° and 210°.

[0091] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. An AC / DC withstand voltage partial discharge test system based on a rectangular time-frequency filter, characterized in that: It comprises a partial discharge ultra-wideband detection system (10), an AC withstand voltage test module (11), a DC withstand voltage test module (12), a two-dimensional time-frequency window dynamic display module (13), a rectangular time-frequency filter algorithm module (14) and a withstand voltage partial discharge data dynamic display and storage module (15); The partial discharge ultra-wideband detection system (10) is respectively connected to an AC withstand voltage test module (11), a DC withstand voltage test module (12) and a two-dimensional time-frequency window dynamic display module (13); the two-dimensional time-frequency window dynamic display module (13) is respectively connected to a rectangular time-frequency filter algorithm module (14) and a withstand voltage partial discharge data dynamic display and storage module (15); the rectangular time-frequency filter algorithm module (14) is connected to a withstand voltage partial discharge data dynamic display and storage module (15); The specific processing process of the two-dimensional time-frequency window dynamic display module (13) is as follows: Step 101, time domain pulse data preprocessing, the specific preprocessing process is: The pulse groups obtained by ultra-wideband detection are preprocessed as follows: Where: a i is the amplitude corresponding to the i-th point, Δt(i-1) is the time corresponding to the i-th point, and Δt is the sampling time interval; Step 102: Discrete fast short-time Fourier transform of the pulse group waveform, For all waveforms of the pulse group, ii (t ii ) is used for discrete short-time Fourier transform, and we can get: Where: w(im) is a window function with a length of m; According to equations (2) and (3), p ii (t ii ) ii (f ii ) is processed as: M i is the DSTFT amplitude corresponding to the i-th point, Δf(i-1) is the frequency component corresponding to the i-th point; Step 103: Dynamic display of the two-dimensional time-frequency window of the pulse group. From equations (2) and (4), we can get the pulse waveform-time series, i.e. the two-dimensional time-frequency window (T, F) corresponding to the pulse group: jj for: The specific processing process of the rectangular time-frequency filter algorithm module (14) is as follows: Step 201. According to the two-dimensional time-frequency window (T, F) of the pulse group jj Dynamic display, that is, determine the position P of the rectangular time-frequency filter according to the (T, F) parameter distribution of the pulses before and after the start of the withstand voltage test under actual working conditions i ; Step 202. Use the mouse to move the cursor to position P on the two-dimensional time-frequency window software display control. i Set a rectangular time-frequency filter Filter(i) = (T1_i, F1_i), (T2_i, F2_i), (T3_i, F3_i), (T4_i, F4_i); Step 203. Get all (T, F) in the current rectangular time-frequency filter Filter (i) jj Corresponding pulse waveform-waveform time series Step 204. Dynamic display and storage module (15) based on withstand voltage partial discharge data The corresponding parameters include pulse time and frequency domain waveforms, peak-phase sequence, number of pulses, and pulse maximum value; Step 205. Dynamically display the parameter distribution in the two-dimensional time-frequency window and the correlation between the time-frequency filter Filter (i) If the working conditions change, remove the existing time-frequency filter Filter(i) and reset Step 202.

2. According to claim 1, an AC / DC withstand voltage partial discharge test system based on a rectangular time-frequency filter is characterized in that: The partial discharge ultra-wideband detection system (10) comprises a broadband detection impedance, a signal conditioning unit, a data acquisition terminal, and an industrial control PC equipped with control and display software, which are connected in sequence; In the partial discharge ultra-wideband detection system (10), under the AC withstand voltage test module (11), the data acquisition terminal records the corresponding pulse group, which is a pulse waveform-phase time sequence.

3. The AC / DC withstand voltage partial discharge test system based on rectangular time-frequency filter according to claim 1 is characterized in that: The partial discharge ultra-wideband detection system (10) comprises a broadband detection impedance, a signal conditioning unit, a high-speed oscilloscope, and a laptop computer equipped with control and display software, which are connected in sequence; In the partial discharge ultra-wideband detection system (10), under the DC withstand voltage test module (12), the high-speed oscilloscope records the corresponding pulse group, which is a pulse waveform-time sequence.

4. The AC / DC withstand voltage partial discharge test system based on a rectangular time-frequency filter according to claim 2 or 3, characterized in that: The sampling rate of the data acquisition terminal or high-speed oscilloscope recording device must be 100MS / s or above, the analog bandwidth must be 50MHz or above, and the recorded and stored pulse waveform-time series is defined as follows: Pulse ii (p ii (i),t ii ,U ii ),ii=1,2,…,N;i=1,2,…,k (1) Where: ii is the iith pulse; N is the pulse current waveform p ii (i) The total number of; k is each pulse current waveform p ii (i) The number of points, pulse waveform p ii (i) It consists of k points, U ii is the pulse current waveform p ii (i) The withstand voltage value applied to the test piece at the time of triggering.

5. The AC / DC withstand voltage partial discharge test system based on rectangular time-frequency filter according to claim 1, characterized in that: The AC withstand voltage test module (11) adopts an AC withstand voltage test system, specifically a long-time induction withstand voltage PD test circuit in which the converter transformer applies pressure on the grid side, comprising a generator set G, a compensating reactor L, a voltage measuring device V, an intermediate transformer T and a test product.

6. The AC / DC withstand voltage partial discharge test system based on rectangular time-frequency filter according to claim 1, characterized in that: The DC withstand voltage test module (12) adopts a DC withstand voltage test system, specifically a converter transformer DC external withstand voltage PD test circuit, including a DC generator ZF, a protective resistor, a voltage measuring device V and a test product.

7. The AC / DC withstand voltage partial discharge test system based on rectangular time-frequency filter according to claim 1, characterized in that: The pulse distribution that appears before the voltage is applied is the noise source, and a rectangular time-frequency filter Filter(1) can be set to observe its characteristics; Similarly, the pulse distribution that appears after the voltage is applied is a PD source, and a rectangular time-frequency filter Filter (2) can be set again.

8. The AC / DC withstand voltage partial discharge test system based on rectangular time-frequency filter according to claim 1, characterized in that: The withstand voltage partial discharge data dynamic display and storage module (15) stores all waveforms of the pulse group in real time, and displays corresponding parameters including pulse time domain and frequency domain waveforms, peak-phase sequence, pulse number, and pulse maximum value.

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