CN110398675A - A method and system for measuring power frequency and impulse superimposed voltage waveforms - Google Patents

Abstract

The invention discloses a method for measuring power frequency and impulse superimposed voltage waveforms. The method includes: converting high-voltage power frequency voltage and superimposed impulse voltage waveforms into low-voltage signals through a broadband voltage divider, and converting the low-voltage signals into low-voltage signals. output to the high sampling rate acquisition unit and the low sampling rate acquisition unit respectively; calculate the low voltage signal received by the high sampling rate acquisition unit through the impulse voltage calculation module, and obtain the peak voltage and time parameters of the impulse voltage; The calculation module calculates the low-voltage signal received by the low-sampling rate acquisition unit, and obtains the peak voltage and frequency parameters of the power frequency voltage; the high-sampling rate acquisition unit and the low-sampling rate acquisition unit are triggered by the phase calculation module. The low-voltage signal received by the unit is superimposed on the time axis, and the trigger phase is calculated at the position of the high-voltage power frequency voltage cycle at the trigger moment.

Description

A method and system for measuring power frequency and impulse superimposed voltage waveforms

technical field

The invention relates to the technical field of transient voltage measurement, and more particularly, to a method and a system for measuring power frequency and impulse superimposed voltage waveforms.

Background technique

In order to assess the insulation capacity of lightning protection equipment such as arresters, in addition to separate power frequency withstand voltage test and impulse withstand voltage test, superimposed voltage test is sometimes required. At present, the most used is the power frequency voltage superimposed impulse voltage test, which is the superposition of different test voltages generated by two independent power sources connected in an appropriate way, and the two power sources are simultaneously applied to one terminal of the test product. A protective element is required between the two power supplies to prevent the voltage of one power supply from damaging the other power supply system. The technical parameters of the superimposed voltage test include the voltage value U, the time delay Δt and the parameters of the two voltage components. The voltage value refers to the superposition of two test voltages caused by acting on the test sample, the combined voltage U=U ₁ +U ₂ . Time delay refers to the time interval between when two voltage components reach their peaks. Figure 1 is a typical superimposed voltage test circuit in the prior art. It can be seen from the figure that there is an isolation spherical gap between the impulse voltage generator and the test product to prevent the power frequency voltage from being applied to the impulse voltage generator. The voltage generator constitutes a voltage divider system to prevent the impulse voltage applied to the power frequency voltage from being too high and damaging the power supply equipment.

When the power transmission and transformation equipment or nearby objects in the power system are struck by lightning, the lightning overvoltage will invade the power system directly or through induction, and the waveform of the transient overvoltage is the superimposed voltage of the power frequency voltage and the lightning impulse voltage.

For the measurement of the superimposed voltage, the acquisition instrument is generally used to measure. The main problem at this point is that the superimposed waveform contains a very wide range of frequencies, from 50Hz values to MHz. The power frequency voltage needs to be measured for at least 3 cycles, and the measurement time cannot be less than 60ms, so that the sampling rate cannot be too high, and the sampling rate is too low to completely record the impulse voltage waveform, resulting in inaccurate voltage peak calculation. If the sampling rate is too high, the total recording time may be too short, and the complete power frequency voltage cycle cannot be recorded, or the calculation may be slow due to too much recorded data.

Therefore, a technique is needed to realize the measurement of power frequency and impulse superimposed voltage waveforms.

SUMMARY OF THE INVENTION

The technical scheme of the present invention provides a method and a system for measuring power frequency and impulse superimposed voltage waveforms, so as to solve the problem of how to measure power frequency and impulse superimposed voltage waveforms.

In order to solve the above problems, the present invention provides a method for measuring power frequency and impulse superimposed voltage waveforms, the method comprising:

The high-voltage power frequency voltage and the superimposed impulse voltage waveform are converted into low-voltage signals by the broadband voltage divider, and the low-voltage signals are output to the high sampling rate acquisition unit and the low sampling rate acquisition unit respectively;

Calculate the low-voltage signal received by the high sampling rate acquisition unit through the impulse voltage calculation module to obtain the peak voltage and time parameters of the impulse voltage;

The low-voltage signal received by the low sampling rate acquisition unit is calculated by the power-frequency voltage calculation module to obtain the peak voltage and frequency parameters of the power-frequency voltage;

The low-voltage signal received by the high sampling rate acquisition unit and the low sampling rate acquisition unit is superimposed on the time axis by the trigger phase calculation module, and the trigger phase is calculated at the position of the high-voltage power frequency voltage cycle at the trigger moment. .

Preferably, the broadband voltage divider is a capacitor-resistor series voltage divider or a capacitor-resistor parallel voltage divider.

Preferably, the method includes: connecting the protective ball gap to the high voltage side of the broadband voltage divider.

Preferably, it also includes: the high sampling acquisition unit is set to an internal trigger mode, and the low sampling acquisition unit is set to an external trigger mode;

The low-sampling collection unit is triggered by a trigger signal of the high-sampling collection unit.

Preferably, it also includes: the sampling rate of the low sampling rate acquisition unit for measuring the power frequency voltage signal is not less than 100kS/s, and at least 3 cycles are measured;

The sampling rate of the high sampling rate acquisition unit for measuring the impulse voltage signal is not less than 100MS/s, and the measurement time is not less than 200us.

Preferably, the method further includes: respectively triggering the surge voltage and the high-voltage power frequency voltage.

Based on another aspect of the present invention, a measurement system for superimposing voltage waveforms on power frequency and impulse is provided, the system comprising:

a broadband voltage divider, which converts the high-voltage power frequency voltage and the superimposed impulse voltage waveform into a low-voltage signal through the broadband voltage divider, and outputs the low-voltage signal to the high sampling rate acquisition unit and the low sampling rate acquisition unit respectively;

an impulse voltage calculation module, which calculates the low-voltage signal received by the high sampling rate acquisition unit through the impulse voltage calculation module, and obtains the peak voltage and time parameters of the impulse voltage;

a power frequency voltage calculation module, which calculates the low-voltage signal received by the low sampling rate acquisition unit through the power frequency voltage calculation module, and obtains the peak voltage and frequency parameters of the power frequency voltage;

A trigger phase calculation module, which superimposes the low-voltage signals received by the high sampling rate acquisition unit and the low sampling rate acquisition unit on the time axis through the trigger phase calculation module, and at the time of triggering at the high-voltage power frequency The position of the voltage cycle calculates the trigger phase.

Preferably, the broadband voltage divider is a capacitor-resistor series voltage divider or a capacitor-resistor parallel voltage divider.

Preferably, a protection ball gap is included, and the protection ball gap is connected to the high voltage side of the broadband voltage divider for connection.

Preferably, it also includes: the high sampling acquisition unit is set to an internal trigger mode, and the low sampling acquisition unit is set to an external trigger mode;

The low-sampling collection unit is triggered by a trigger signal of the high-sampling collection unit.

Preferably, it also includes: the sampling rate of the low sampling rate acquisition unit for measuring the power frequency voltage signal is not less than 100kS/s, and at least 3 cycles are measured;

The sampling rate of the high sampling rate acquisition unit for measuring the impulse voltage signal is not less than 100MS/s, and the measurement time is not less than 200us.

Preferably, the method further includes: respectively triggering the surge voltage and the high-voltage power frequency voltage.

The technical scheme of the present invention provides a method for measuring power frequency and impulse superimposed voltage waveforms. The method includes: converting high-voltage power frequency voltage and superimposed impulse voltage waveforms into low-voltage signals through a broadband voltage divider, and outputting the low-voltage signals to high-voltage signals respectively. Sampling rate acquisition unit and low sampling rate acquisition unit; calculate the low-voltage signal received by the high sampling rate acquisition unit through the impulse voltage calculation module to obtain the peak voltage and time parameters of the impulse voltage; collect the low sampling rate through the power frequency voltage calculation module The low-voltage signal received by the unit is calculated to obtain the peak voltage and frequency parameters of the power frequency voltage; the low-voltage signal received by the high sampling rate acquisition unit and the low sampling rate acquisition unit is superimposed on the time axis through the trigger phase calculation module, and the trigger time is passed. The trigger phase is calculated at the position of the high-voltage power frequency voltage cycle. The method and system for accurate measurement of power frequency/shock superimposed waveforms proposed by the technical solution of the present invention can accurately acquire key waveform parameters on superimposed waveforms by using two acquisition units with different sampling rates, and solve the problem of measurement time and sampling rate. The contradiction between them not only satisfies the accurate acquisition of the high-frequency voltage waveform, but also improves the calculation speed and ensures the work efficiency.

Description of drawings

Exemplary embodiments of the present invention may be more fully understood by reference to the following drawings:

Fig. 1 is the schematic diagram of the superimposed voltage test principle according to the prior art;

2 is a flow chart of a method for measuring power frequency and impulse superimposed voltage waveforms according to a preferred embodiment of the present invention;

3 is a flow chart of a method for measuring power frequency and impulse superimposed voltage waveforms according to a preferred embodiment of the present invention;

4 is a structural diagram of a measurement system for superimposing voltage waveforms on power frequency and impulse according to a preferred embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for the purpose of this thorough and complete disclosure invention, and fully convey the scope of the invention to those skilled in the art. The terms used in the exemplary embodiments shown in the drawings are not intended to limit the invention. In the drawings, the same elements/elements are given the same reference numerals.

Unless otherwise defined, terms (including scientific and technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is to be understood that terms defined in commonly used dictionaries should be construed as having meanings consistent with the context in the related art, and should not be construed as idealized or overly formal meanings.

2 is a flow chart of a method for measuring power frequency and impulse superimposed voltage waveforms according to a preferred embodiment of the present invention. The embodiment of the present application proposes a power frequency/impulse superimposed voltage waveform measurement method, which realizes the collection and processing of voltage signals including a wide frequency range, and provides technical support for the measurement of transient overvoltage in a power system. As shown in Figure 2, a method for measuring power frequency and impulse superimposed voltage waveforms includes:

Preferably, in step 201: the high-voltage power frequency voltage and the superimposed impulse voltage waveform are converted into low-voltage signals by a broadband voltage divider, and the low-voltage signals are output to the high sampling rate acquisition unit and the low sampling rate acquisition unit respectively. Preferably, the broadband voltage divider is: a capacitor, a resistor series voltage divider or a capacitor, a resistor parallel voltage divider. Preferably, the method includes: connecting the protective ball gap to the high voltage side of the broadband voltage divider. Preferably, the method further includes: respectively triggering the impulse voltage and the high-voltage power frequency voltage.

The broadband voltage divider of the present application converts the superimposed impulse voltage waveform of the high-voltage power frequency voltage into a low-voltage signal that can be collected by the data acquisition unit. The output voltage signal of the same broadband voltage divider is measured by two acquisition units, a high sampling rate acquisition unit and a low sampling rate acquisition unit. The broadband voltage divider is a capacitor, resistor series voltage divider or capacitor, resistor parallel voltage divider. In the power frequency/impulse combined voltage waveform measurement method of the present application, the high-voltage side of the broadband voltage divider is connected to the rear end of the protective ball gap. Due to the existence of the protective ball gap, the actual impulse voltage waveform is inconsistent with the output waveform of the impulse voltage generator. The rise time is steeper. A T-type connector is added to the end of the coaxial cable of the broadband voltage divider of the present application, and the measurement signal is simultaneously connected to two data acquisition units with different sampling rates. Two different sampling rate measurement data acquisition units are a high sampling rate acquisition unit and a low sampling rate acquisition unit.

Preferably, in step 202: the impulse voltage calculation module is used to calculate the low voltage signal received by the high sampling rate acquisition unit to obtain the peak voltage and time parameters of the impulse voltage. The present application processes the discrete data collected by the high sampling rate acquisition unit through the impulse voltage calculation module, and obtains the impulse voltage peak voltage and time parameters.

Preferably, in step 203: the low-voltage signal received by the low sampling rate acquisition unit is calculated by the power frequency voltage calculation module to obtain the peak voltage and frequency parameters of the power frequency voltage. Preferably, the high sampling acquisition unit is set to an internal trigger mode, and the low sampling acquisition unit is set to an external trigger mode; the low sampling acquisition unit is triggered by a trigger signal of the high sampling acquisition unit. Preferably, the sampling rate of the low sampling rate acquisition unit that measures the power frequency voltage signal is not less than 100kS/s, and measures at least 3 cycles; the sampling rate of the high sampling rate acquisition unit that measures the impulse voltage signal is not less than 100MS/s, and the measurement time Not less than 200us.

The present application processes the discrete data collected by the low sampling rate acquisition unit through the power frequency voltage calculation module, and calculates parameters such as the power frequency voltage peak value and frequency. In this application, the high sampling rate acquisition unit is set to an internal trigger mode, and the low sampling rate acquisition unit is set to an external trigger mode, and the trigger signal of the high sampling rate acquisition unit is used to trigger the low sampling rate acquisition unit, which can ensure that the trigger times of the two acquisition units are consistent. The sampling rate of the data acquisition unit for measuring the power frequency voltage signal of the present application is not less than 100kS/s, and it measures at least 3 cycles. The sampling rate of the data single-stage unit for measuring the impulse voltage signal is not less than 100MS/s, and the measurement time is not less than 200us. The two acquisition units of this application measure the same signal and can be placed in a metal shielding box to eliminate the interference of surrounding electromagnetic fields.

Preferably, in step 204: the low-voltage signals received by the high sampling rate acquisition unit and the low sampling rate acquisition unit are superimposed on the time axis by the trigger phase calculation module, and the trigger phase is calculated at the position of the high-voltage power frequency voltage cycle at the trigger time. As shown in FIG. 3 , the present application superimposes the data obtained by the two acquisition units on the time axis through the trigger phase calculation module, and calculates the trigger phase at the position of the power frequency voltage cycle at the trigger time. At this point, the maximum peak value of the superimposed waveform can be further calculated. The waveform superposition display module displays the superimposed data and waveform parameter results on the PC.

The embodiments of the present application are suitable for measuring superimposed voltage waveforms in the laboratory, and also for measuring actual transient overvoltage waveforms in substations and extracting characteristic parameters. In the present application, by using two acquisition units with different sampling rates, the key waveform parameters on the superimposed waveform can be accurately obtained, and the contradiction between the measurement time and the sampling rate is solved. In the present application, the transient voltage and the power frequency voltage are separately triggered, which simplifies the calculation and improves the calculation speed. The embodiments of the present application are also applicable to transient overvoltage measurement at the substation site.

The following examples illustrate the embodiments of the present application:

The measurement method of the superimposed waveform of 100kV power frequency voltage and 200kV impulse voltage is as follows, using an 800kV weakly damped voltage divider to convert the high-voltage superimposed voltage waveform into a low-voltage signal, and the output voltage waveform of the voltage divider outputs the two digital oscilloscopes MDO3052 through the T-type connector. signal input. The sampling rate of the high sampling rate digital oscilloscope is set to 100MS/s, and the edge is triggered. The sample rate of the low sample rate digital oscilloscope is set to 100kS/s, with external triggering. The trigger signal for a low sample rate oscilloscope is provided by a high sample rate digital oscilloscope. Two digital oscilloscopes are housed in the same metal shielded box.

The data collected by the digital oscilloscope is transmitted to different PCs through the network cable. The impulse voltage calculation module calculates the impulse voltage peak voltage, rise time T ₁ and half-peak time T ₂ , and outputs the filtered impulse data file. The power frequency voltage calculation module calculates parameters such as voltage peak-to-peak value, effective value and frequency, and outputs the filtered power frequency data file. The trigger phase calculation module superimposes the two data files on the same time axis after the trigger time point, so as to calculate the characteristic parameters such as the superposition phase θ, the time delay and the voltage peak value of the superposition point.

FIG. 4 is a system structure diagram for measuring power frequency and impulse superimposed voltage waveforms according to a preferred embodiment of the present invention. As shown in FIG. 4 , the present application provides a system for measuring power frequency and impulse superimposed voltage waveforms, 1 is a broadband voltage divider, 2 is a coaxial cable, 3 is a T-connector, and 4 is a high sampling Rate acquisition unit, 5 is a low sampling rate acquisition unit, 6 is an external trigger cable, 7 is a metal shielding box, 8 is a network cable, and 9 is a computer or various intelligent terminals.

The broadband voltage divider 1 converts the high-voltage power frequency voltage and the superimposed impulse voltage waveform into a low-voltage signal through the broadband voltage divider 1, and outputs the low-voltage signal to the high sampling rate acquisition unit 4 and the low sampling rate acquisition unit 5 respectively; The voltage divider 1 is: a capacitor-resistor series voltage divider or a capacitor-resistor parallel voltage divider. Preferably, the system further includes a protection ball gap, and the protection ball gap is connected to the high voltage side of the broadband voltage divider for connection.

The impulse voltage calculation module calculates the low-voltage signal received by the high sampling rate acquisition unit 4 through the impulse voltage calculation module, and obtains the peak voltage and time parameters of the impulse voltage;

The power frequency voltage calculation module calculates the low-voltage signal received by the low sampling rate acquisition unit 5 through the power frequency voltage calculation module, and obtains the peak voltage and frequency parameters of the power frequency voltage;

Preferably, the system further includes: the sampling rate of the low sampling rate acquisition unit for measuring the power frequency voltage signal is not less than 100kS/s, and at least 3 cycles are measured; the sampling rate of the high sampling rate acquisition unit for measuring the impulse voltage signal is not less than 100MS/s s, the measurement time is not less than 200us.

The trigger phase calculation module superimposes the low-voltage signals received by the high sampling rate acquisition unit and the low sampling rate acquisition unit on the time axis through the trigger phase calculation module, and calculates the trigger phase at the position of the high-voltage power frequency voltage cycle at the trigger time.

Preferably, the system further includes: the high sampling acquisition unit is set with an internal trigger mode, and the low sampling acquisition unit is set with an external trigger mode; the low sampling acquisition unit is triggered by a trigger signal of the high sampling acquisition unit.

Preferably, the system further includes: triggering the impulse voltage and the high-voltage power frequency voltage respectively.

The system 400 for measuring power frequency and impulse superimposed voltage waveforms in the preferred embodiment of the present invention corresponds to the method 200 for measuring power frequency and impulse superimposed voltage waveforms in another preferred embodiment of the present invention, where No further description will be given.

The present invention has been described with reference to a few embodiments. However, as is known to those skilled in the art, other embodiments than the above disclosed invention are equally within the scope of the invention, as defined by the appended patent claims.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/the/the [means, component, etc.]" are open to interpretation as at least one instance of said means, component, etc., unless expressly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Claims (12)

1. a kind of measurement method for power frequency and impact superimposed voltage waveform, which comprises

High pressure power-frequency voltage and superposition High Voltage Impulse Waveform are converted into low-voltage signal by wideband divider, the low pressure is believed It number is exported respectively to high sampling rate acquisition unit and low sampling rate acquisition unit；

Module is calculated by surge voltage to calculate the received low-voltage signal of the high sampling rate acquisition unit, is obtained The crest voltage and time parameter of surge voltage；

The received low-voltage signal of the low sampling rate acquisition unit is calculated by power-frequency voltage computing module, is obtained The crest voltage and frequency parameter of power-frequency voltage；

By phase-triggered computing module to the high sampling rate acquisition unit and the received institute of the low sampling rate acquisition unit It states low-voltage signal to be overlapped on a timeline, triggering is calculated in the position of the high pressure power-frequency voltage cycle by triggering moment Phase.

2. according to the method described in claim 1, the wideband divider are as follows: capacitor, resistance series voltage divider or capacitor, resistance Parallel voltage divider.

3. according to the method described in claim 1, including: the high-pressure side that protective ball gap is connected to the wideband voltage divider It carries out connected.

4. according to the method described in claim 1, further include: internal trigger mode is arranged in the high sampled acquisition unit, described low External trigger formula is arranged in sampled acquisition unit；

The low sampled acquisition unit is triggered by the trigger signal of the high sampled acquisition unit.

5. according to the method described in claim 1, further include: the low sampling rate acquisition unit of measurement power-frequency voltage signal Sample rate is not less than 100kS/s, measures at least three cycle；

The sample rate for measuring the high sampling rate acquisition unit of surge voltage signal is not less than 100MS/s, and time of measuring is not short In 200us.

6. according to the method described in claim 1, further include: it is carried out respectively to the surge voltage and the high pressure power-frequency voltage Triggering.

7. a kind of measuring system for power frequency and impact superimposed voltage waveform, the system comprises:

High pressure power-frequency voltage and superposition High Voltage Impulse Waveform are converted to low-voltage signal by wideband divider by wideband divider, The low-voltage signal is exported respectively to high sampling rate acquisition unit and low sampling rate acquisition unit；

Surge voltage calculates module, and it is received to the high sampling rate acquisition unit described to calculate module by the surge voltage Low-voltage signal is calculated, and the crest voltage and time parameter of surge voltage are obtained；

Power-frequency voltage computing module, it is received to the low sampling rate acquisition unit described by the power-frequency voltage computing module Low-voltage signal is calculated, and the crest voltage and frequency parameter of power-frequency voltage are obtained；

Phase-triggered computing module to the high sampling rate acquisition unit and described low is adopted by the phase-triggered computing module The received low-voltage signal of sample rate acquisition unit is overlapped on a timeline, by triggering moment in the high pressure power frequency electric The position of cycle is pressed to calculate phase-triggered.

8. system according to claim 7, the wideband divider are as follows: capacitor, resistance series voltage divider or capacitor, resistance Parallel voltage divider.

9. protective ball gap is connected to the wideband voltage divider by system according to claim 7, including protective ball gap High-pressure side carry out it is connected.

10. system according to claim 7, further includes: internal trigger mode is arranged in the high sampled acquisition unit, described low External trigger formula is arranged in sampled acquisition unit；

The low sampled acquisition unit is triggered by the trigger signal of the high sampled acquisition unit.

11. system according to claim 7, further includes: the low sampling rate acquisition unit of measurement power-frequency voltage signal Sample rate be not less than 100kS/s, measure at least three cycle；

The sample rate for measuring the high sampling rate acquisition unit of surge voltage signal is not less than 100MS/s, and time of measuring is not short In 200us.

12. system according to claim 7, further includes: carried out respectively to the surge voltage and the high pressure power frequency electric The triggering of pressure.