Method for generating pulse signal, pulse generating device and partial discharge measurement system

Abstract

The present invention discloses a method for generating a pulse signal, a pulse generating device, and a partial discharge measurement system, which relates to the technical field of signal generating devices, and solves the problems of relatively low pulse peak values of existing pulse generators and relatively large rise times of output pulses. The main technical solution is as follows: An AC signal source is obtained; the AC signal source is subjected to two-stage in-phase signal amplification processing to obtain an AC electrical signal; the AC electrical signal is successively subjected to rectification, voltage reduction, and delay processing to generate a pulse signal. The present invention performs signal amplification processing on the AC signal source to reduce the relative influence of external interference, obtains an AC electrical signal, and based on the subsequent rectification, voltage reduction, and delay processing, which play the roles of edge sharpening of the AC electrical signal, allowing the generation of narrow pulses to maximize the signal bandwidth, and reducing ringing, so that when the rise time of the pulse front decreases, the overshoot pulse peak value increases.

Description

Technical Field

[0001] The present invention relates to the technical field of signal generating devices, and more specifically, to a method for generating pulse signals, a pulse generating device, and a partial discharge measurement system. Background Art

[0002] Gas-insulated switchgear has characteristics such as non-flammability, non-explosion, and low noise. Currently, SF6 gas is basically used as the main insulating and cooling medium in the existing gas-insulated switchgear. During the manufacturing, maintenance, installation, transportation, operation, and overhaul of gas-insulated switchgear, insulation defects will occur inside the equipment cavity, resulting in partial discharge, and further leading to more serious insulation problems. Therefore, the detection of partial discharge in gas-insulated switchgear becomes particularly important.

[0003] Pulse generators are used in the field of partial discharge (PD) measurement to artificially generate signals similar to partial discharge. Therefore, an important element of any partial discharge measurement system is a pulse test generator, which can verify the functions and settings of the entire partial discharge measurement chain. Different methods can be used to generate very short and very fast edge pulses. The maximum pulse peak of existing pulse signal generators is 8.8V, and the rise time of the output pulse is 135ps, which no longer meets the measurement requirements of partial discharge.

[0004] Therefore, how to increase the pulse peak of the pulse signal generator and reduce the rise time of the output pulse to meet the measurement requirements of partial discharge is an urgent problem to be solved currently. Summary of the Invention

[0005] In order to solve the problems of relatively low pulse peak and relatively large rise time of the output pulse of the existing pulse generator, the present application provides a method for generating pulse signals, a pulse generating device, and a partial discharge measurement system. In terms of the signal generation method, by obtaining an AC signal source, performing signal amplification processing on the AC signal source to reduce the relative influence of external interference, an AC electrical signal is obtained. Based on subsequent rectification, voltage reduction, and delay processing, it plays a role in edge sharpening of the AC electrical signal, allowing the generation of narrow pulses to maximize the signal bandwidth and reducing ringing, so that when the rise time of the pulse front decreases, the peak value of the overshoot pulse increases. In terms of the pulse generating device, a programmable signal generator is used as the signal source, which can output various signals. A pair of preamplifiers is connected to the output end of the signal generator to amplify the signal of the signal source. A step recovery diode is connected to the output end of the preamplifier to form an SRD edge sharpener with a pulse forming network to generate the required narrow pulse, and thus output a pulse signal.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] In a first aspect, the present application provides a method for generating a pulse signal, including:

[0008] Obtain an AC signal source;

[0009] Perform two-stage in-phase signal amplification processing on the AC signal source to obtain an AC electrical signal;

[0010] Perform rectification, step-down, and delay processing on the AC electrical signal in sequence to generate a pulse signal.

[0011] In a possible implementation, performing two-stage in-phase signal amplification processing on the AC signal source to obtain an AC electrical signal includes:

[0012] While performing the first-stage in-phase signal amplification processing on the AC signal source, perform a filtering process on the AC signal source once to obtain an amplified signal;

[0013] While performing the second-stage in-phase signal amplification processing on the amplified signal, perform a filtering process on the amplified signal once again to obtain an AC electrical signal.

[0014] In a possible implementation, the signal gain of the first-stage in-phase signal amplification processing is 4, and the signal gain of the second-stage in-phase signal amplification processing is 2.

[0015] In a possible implementation, performing rectification, step-down, and delay processing on the AC electrical signal in sequence to generate a pulse signal includes:

[0016] Perform rectification processing on the AC electrical signal to obtain a DC electrical signal;

[0017] Perform forward voltage drop processing on the DC electrical signal to reduce the forward voltage drop of the DC electrical signal to obtain an electrical signal;

[0018] Perform delay processing on the electrical signal and then enter a pulse forming network to generate a pulse signal.

[0019] In a second aspect, the present application provides a pulse generating device for implementing the method for generating a pulse signal according to any one of the first aspects, including a signal generator, a preamplifier, and a pulse generator;

[0020] The signal generator is used to generate and output an AC signal source, and the AC signal source includes a square wave signal and a sine wave signal;

[0021] The preamplifier is used to perform two-stage in-phase signal amplification processing on the AC signal source to obtain an AC electrical signal;

[0022] The pulse generator is used to perform rectification, step-down, and delay processing on the AC electrical signal in sequence to generate a pulse signal.

[0023] In a possible implementation, the signal generator is a programmable signal generator, which has three high-frequency and three ultra-high-frequency outputs.

[0024] In a possible implementation, the preamplifier includes a first-stage preamplifier and a second-stage preamplifier, wherein the maximum output voltage of the first-stage preamplifier and the second-stage preamplifier is 20V;

[0025] A first capacitor is connected in parallel between the negative input terminal and the output terminal of the IC chip of the first-stage preamplifier, and is used for performing a first filtering process on the AC signal source;

[0026] A second capacitor is connected in parallel between the negative input terminal and the output terminal of the IC chip of the second-stage preamplifier, and is used for performing a second filtering process on the amplified signal output by the first-stage preamplifier. The output terminal of the signal generator is connected to the positive input terminal of the first-stage amplifier, and the output terminal of the first-stage amplifier is connected to the positive input terminal of the second amplifier.

[0027] In a possible implementation, the pulse generator includes a DC bias unit, a capacitor C2, a resistor R2, a Schottky diode D1, a step recovery diode D2, and a capacitor C3;

[0028] The signal output terminal of the preamplifier is connected to the capacitor C2, the capacitor C2 is connected to the resistor R2, and the DC bias unit is introduced between the capacitor C2 and the resistor R2 to rectify the AC signal;

[0029] The resistor R2 is connected to the positive electrode of the Schottky diode D1;

[0030] The positive electrode of the Schottky diode D1 is connected to the negative electrode of the step recovery diode D2 through a delay line;

[0031] The negative electrode of the step recovery diode D2 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is connected to the output terminal of the pulse generator.

[0032] In a possible implementation, the Schottky diode D1 and the step recovery diode D2 are connected in parallel. Correspondingly, the negative electrode of the Schottky diode D1 is grounded, and the positive electrode of the step recovery diode D2 is grounded.

[0033] In a third aspect, the present application provides a partial discharge measurement system, including a pulse generating device as described in any one of the second aspects.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] In terms of the signal generation method of this application, an AC signal source is acquired, and the AC signal source is subjected to signal amplification processing to reduce the relative influence of external interference, obtaining an AC electrical signal. Based on subsequent rectification, voltage reduction, and delay processing, it plays the roles of edge sharpening of the AC electrical signal, allowing the generation of narrow pulses to maximize the signal bandwidth, and reducing ringing, so that when the rising time of the pulse front decreases, the peak value of the overshoot pulse increases. In terms of the pulse generator, a programmable signal generator is used as the signal source, which can output various signals. A pair of preamplifiers is connected to the output end of the signal generator to amplify the signal of the signal source. A step recovery diode is connected to the output end of the preamplifier to form an SRD edge sharpener with a pulse forming network to generate the required narrow pulse, thereby outputting a pulse signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, form a part of this application, and do not constitute a limitation on the embodiments of the present invention. In the drawings:

[0037] Figure 1 is a schematic flowchart of the pulse signal generation method provided by an embodiment of this application;

[0038] Figure 2 is a schematic structural diagram of the pulse generating device provided by an embodiment of this application.

[0039] Figure 3 is a circuit diagram of a two-stage preamplifier provided by an embodiment of this application;

[0040] Figure 4 is a circuit diagram of the pulse generator provided by an embodiment of this application;

[0041] Figure 5 is a waveform example diagram of a conventional pulse generator in the prior art;

[0042] Figure 6 is a waveform example diagram of the pulse generating device provided by an embodiment of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in combination with the embodiments and the drawings. The illustrative embodiments and descriptions thereof of the present invention are only used to explain the present invention and do not constitute a limitation on the present invention.

[0044] It should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0045] As Figure 1 shown, an embodiment of the present application provides a method for generating a pulse signal, in which the pulse amplitude of the pulse signal is increased and the rise time of the output pulse signal is reduced, including:

[0046] S1. Obtain an AC signal source;

[0047] S2. Perform two-stage in-phase signal amplification processing on the AC signal source to obtain an AC electrical signal;

[0048] S3. Generate a pulse signal after successively performing rectification, voltage reduction, and delay processing on the AC electrical signal.

[0049] In this embodiment, in step S1, the obtained AC signal source can be generated by devices such as a function signal generator and an oscilloscope, and it can be a square wave signal, a sine wave signal, a cosine wave signal, etc.

[0050] In step S2, the two-stage in-phase signal amplification processing is to convert the current signal of the AC signal source into a voltage signal through two identical operational amplifier circuits or operational amplifiers, and perform amplification, filtering, and summing processing on the signal. These are all conventional operations of the amplification processing, so no detailed description is given here. The two-stage in-phase signal amplification processing is to meet the needs of the load and facilitate the generation of subsequent waveforms.

[0051] In step S3, the signal processed based on step S2 is further processed to form a pulse signal. Specifically, rectification is to convert the AC signal into a DC signal by means of a DC bias, voltage reduction is to reduce the forward voltage drop of the electrical signal after signal amplification processing, and the principle of delay processing: the pulse width of the output Gaussian pulse is proportional to the length of the delay line, and it can be flexibly adjusted by changing the position of the Schottky diode on the delay line. Another advantage of the pulse generator configuration described here is the position of the pulse forming circuit in the input part of the SRD sharpener rather than in the usual position in the output part. This enables a low ringing level to be maintained.

[0052] In summary, in the pulse signal generation method according to the embodiments of the present application, by obtaining an AC signal source, performing signal amplification processing on the AC signal source to reduce the relative influence of external interference, an AC electrical signal is obtained. Based on subsequent rectification, step-down, and delay processing, the edge of the AC electrical signal is sharpened, narrow pulses are allowed to be generated to maximize the signal bandwidth, and ringing is reduced, so that when the rising time of the pulse front decreases, the peak value of the overshoot pulse increases.

[0053] In a possible implementation, performing two-stage in-phase signal amplification processing on the AC signal source to obtain an AC electrical signal includes:

[0054] While performing the first-stage in-phase signal amplification processing on the AC signal source, performing a filtering process on the AC signal source once to obtain an amplified signal;

[0055] While performing the second-stage in-phase signal amplification processing on the amplified signal, performing a filtering process on the amplified signal once again to obtain an AC electrical signal.

[0056] Specifically, in this embodiment, the effects that can be achieved by performing the two-stage in-phase signal amplification processing in sequence have been described in detail in step S2 of the above embodiment, so they will not be described here again.

[0057] In a possible implementation, the signal gain of the first-stage in-phase signal amplification processing is 4, and the signal gain of the second-stage in-phase signal amplification processing is 2.

[0058] Specifically, as Figure 3 shown, taking R 5 / R 4 = 3, R 13 / R 12 = 2, that is, the gain |V out / V in | = (R 5 / R 4 + 1)R 13 / R 12 .

[0059] In a possible implementation, after sequentially performing rectification, step-down, and delay processing on the AC electrical signal to generate a pulse signal, it includes:

[0060] Performing rectification processing on the AC electrical signal to obtain a DC electrical signal;

[0061] Performing a forward voltage drop processing on the DC electrical signal to reduce the forward voltage drop of the DC electrical signal to obtain an electrical signal;

[0062] Performing delay processing on the electrical signal and then entering a pulse forming network to generate a pulse signal.

[0063] Specifically, the processing method of the corresponding signal has been described in detail in step S3 of the above embodiment, so it will not be described here again.

[0064] Based on the same technical concept, as Figure 2 shown, an embodiment of the present application further provides a pulse generating device for implementing the pulse signal generating method described in any one of the above embodiments, including a signal generator, a preamplifier, and a pulse generator;

[0065] The signal generator is used to generate and output an AC signal source, which includes a square wave signal and a sine wave signal;

[0066] The preamplifier is used to perform two-stage in-phase signal amplification processing on the AC signal source to obtain an AC electrical signal;

[0067] The pulse generator is used to generate a pulse signal after rectifying, stepping down, and delaying the AC electrical signal in sequence.

[0068] In this embodiment, the signal generator is powered by a main power supply and synchronized with the main power supply, can be programmed through software on a PC using USB, and allows programming of different PD phase resolution modes.

[0069] The preamplifier uses a fast operational amplifier, and the THS3491 type operational amplifier can be selected.

[0070] The pulse generator uses a pulse generating circuit with an SRD (step recovery diode), and the SRD acts as a leading signal edge sharpener, and also includes a pulse forming network, which generates the required narrow pulse.

[0071] In a possible implementation, the signal generator is a programmable signal generator, and this signal generator has three high-frequency and three ultra-high-frequency outputs.

[0072] Specifically, the programmable signal generator has three high-frequency and three ultra-high-frequency output ports, which is not described in detail in the prior art.

[0073] As Figure 3 shown, this embodiment provides a circuit diagram of a two-stage preamplifier. The preamplifier includes a first-stage preamplifier and a second-stage preamplifier. Among them, the maximum output voltage of the first-stage preamplifier and the second-stage preamplifier is 20V;

[0074] A first capacitor is connected in parallel between the negative input terminal and the output terminal of the IC chip of the first-stage preamplifier for performing the first filtering process on the AC signal source;

[0075] A second capacitor is connected in parallel between the negative input terminal and the output terminal of the IC chip of the second-stage preamplifier, which is used to perform a second filtering process on the amplified signal output by the first-stage preamplifier. The output terminal of the signal generator is connected to the positive input terminal of the first-stage amplifier, and the output terminal of the first-stage amplifier is connected to the positive input terminal of the second amplifier.

[0076] Specifically, the maximum recommended output voltage of the selected first-stage and second-stage preamplifiers is 20V, which is set for a power supply voltage of ±15V. Therefore, at an input voltage of about 2 - 2.5V, its output meets the expected requirements. This ensures that the input signal of the programmable signal generator will not be distorted.

[0077] As Figure 2 shown, the addition of the first capacitor C14 and the second capacitor C19 in the first-stage and second-stage preamplifiers is to limit the frequency range of the signal and prevent oscillation in the two-stage preamplifier.

[0078] As Figure 4 shown, this embodiment provides a circuit diagram of a pulse generator. The pulse generator includes a DC bias unit, a capacitor C2, a resistor R2, a Schottky diode D1, a step recovery diode D2, and a capacitor C3;

[0079] The signal output terminal of the preamplifier is connected to the capacitor C2, the capacitor C2 is connected to the resistor R2, and the DC bias unit is introduced between the capacitor C2 and the resistor R2 to rectify the AC signal;

[0080] The resistor R2 is connected to the positive electrode of the Schottky diode D1;

[0081] The positive electrode of the Schottky diode D1 is connected to the negative electrode of the step recovery diode D2 through a delay line;

[0082] The negative electrode of the step recovery diode D2 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is connected to the output terminal of the pulse generator.

[0083] As Figure 4As shown, in this embodiment, based on the step recovery diode D2 and the Schottky diode D1, a different Gaussian pulse formation method is introduced in the design. The SRD is connected in parallel with the transmission line and used as a falling-edge sharpener. In the steady state, the diode is forward-biased and presents a low impedance. The drive waveform applied to the input terminal of the pulse generator reaches the SRD through the coupling capacitor and the delay line. After the SRD is turned off, the fast-falling-time step waveform propagates in two directions away from the SRD. The first step propagates towards the output terminal, while the second step propagates towards the input terminal along the delay line. The parallel Schottky diode (SRD) is reverse-biased and does not affect the circuit before the drive waveform is applied. However, this diode is now turned on by the negative drive pulse and presents a low enough impedance to effectively short-circuit the transmission line. The step waveform propagating from the SRD to the input terminal is negatively reflected by this low impedance and propagates to the output terminal again. Finally, a Gaussian-like pulse is formed by adding the step waveform propagating unchanged from the SRD to the output of the delayed inverted step.

[0084] In a possible implementation, the Schottky diode D1 is connected in parallel with the step recovery diode D2. Correspondingly, the negative electrode of the Schottky diode D1 is grounded, and the positive electrode of the step recovery diode D2 is grounded to reverse-bias the Schottky diode and forward-bias the SRD.

[0085] To illustrate the difference between the pulse generating device of the present application and the prior art, the pulse generating device of the present application is compared with the existing pulse generating device as follows:

[0086] In the prior art, for a pulse generator composed of a rectangular pulse drive and a conventional SRD circuit, as Figure 5 shown, the peak value of the SRD circuit is 8.8V, and the rise time (about 150ps without correcting the oscilloscope rise time) is 135ps.

[0087] In the present application, the drive pulse of the programmable signal generator is further measured using the generator G1 to show that the output pulse of the SRD depends on the amplitude of the drive pulse. Since the pulse has different amplitudes according to the PD mode programming of the signal generator. According to the repetition frequency and the shape of the drive pulse, the rise time of the output pulse also varies slightly. An example of the captured waveform is shown as Figure 6 shown. The observable rise time and pulse amplitude are approximately 100ps and 11.5V respectively

[0088] Based on the same inventive concept, an embodiment of the present application provides a partial discharge measurement system, including a pulse generating device as described in any one of the above embodiments. When the pulse generating device provided by the embodiment of the present application is applied to the partial discharge measurement system, the measurement system can verify the functions and settings of the entire partial discharge measurement chain, and different methods can be used to generate very short and very fast edge pulses to meet the pulse injection requirements for on-site partial discharge measurement.

[0089] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for generating a pulse signal, characterized in that, it is applied to a pulse generating device for a pulse signal, and the pulse generating device includes a signal generator, a preamplifier, and a pulse generator; an AC signal source is generated and output by the signal generator, and the AC signal source is a square wave signal or a sine wave signal; the AC signal source is subjected to two-stage in-phase signal amplification processing by the preamplifier to obtain an AC electrical signal; the pulse generator sequentially rectifies, steps down, and delays the AC electrical signal to generate a pulse signal; the pulse generator includes a DC bias unit, a capacitor C2, a resistor R2, a Schottky diode D1, a step recovery diode D2, and a capacitor C3; the preamplifier includes a first-stage preamplifier and a second-stage preamplifier, wherein the maximum output voltage of the first-stage preamplifier and the second-stage preamplifier is 20V; a first capacitor is connected in parallel between the negative input terminal and the output terminal of the IC chip of the first-stage preamplifier for performing a first filtering process on the AC signal source; a second capacitor is connected in parallel between the negative input terminal and the output terminal of the IC chip of the second-stage preamplifier for performing a second filtering process on the amplified signal output by the first-stage preamplifier, wherein the output terminal of the signal generator is connected to the positive input terminal of the first-stage preamplifier, and the output terminal of the first-stage preamplifier is connected to the positive input terminal of the second preamplifier; the signal output terminal of the preamplifier is connected to the capacitor C2, the capacitor C2 is connected to the resistor R2, and the DC bias unit is introduced between the capacitor C2 and the resistor R2 to rectify the AC electrical signal; the resistor R2 is connected to the positive electrode of the Schottky diode D1; the positive electrode of the Schottky diode D1 is connected to the negative electrode of the step recovery diode D2 through a delay line; the negative electrode of the step recovery diode D2 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is connected to the output terminal of the pulse generator; the Schottky diode D1 and the step recovery diode D2 are connected in parallel, and correspondingly, the negative electrode of the Schottky diode D1 is grounded, and the positive electrode of the step recovery diode D2 is grounded.

2. The method for generating a pulse signal according to claim 1, characterized in that, subjecting the AC signal source to two-stage in-phase signal amplification processing by the preamplifier to obtain an AC electrical signal includes: while performing the first-stage in-phase signal amplification processing on the AC signal source, performing a first filtering process on the AC signal source to obtain an amplified signal; while performing the second-stage in-phase signal amplification processing on the amplified signal, performing a first filtering process on the amplified signal again to obtain an AC electrical signal.

3. The method for generating a pulse signal according to claim 2, characterized in that, the signal gain of the first-stage in-phase signal amplification processing is 4, and the signal gain of the second-stage in-phase signal amplification processing is 2.

4. The method for generating a pulse signal according to claim 1, characterized in that, The pulse signal is generated by sequentially rectifying, stepping down, and delaying the alternating current signal through the pulse generator, including: Rectifying the alternating current signal to obtain a direct current signal; Performing a forward voltage drop process on the direct current signal to reduce the forward voltage drop of the direct current signal and obtain an electrical signal; Performing a delay process on the electrical signal and then entering a pulse forming network to generate a pulse signal.

5. A method for generating a pulse signal according to claim 1, wherein, the signal generator is a programmable signal generator, and the signal generator has three high-frequency and three ultra-high-frequency outputs.

6. A partial discharge measurement system, wherein, it is used to execute a method for generating a pulse signal according to any one of claims 1-5.

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