CN114660367A - Voltage-sharing capacitor test circuit and method for high-voltage direct-current transmission converter valve assembly - Google Patents
Voltage-sharing capacitor test circuit and method for high-voltage direct-current transmission converter valve assembly Download PDFInfo
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- CN114660367A CN114660367A CN202210368792.2A CN202210368792A CN114660367A CN 114660367 A CN114660367 A CN 114660367A CN 202210368792 A CN202210368792 A CN 202210368792A CN 114660367 A CN114660367 A CN 114660367A
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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Abstract
The invention provides a voltage-sharing capacitor test circuit and a voltage-sharing capacitor test method for a high-voltage direct-current transmission converter valve assembly, wherein the converter valve assembly comprises a plurality of thyristor stages connected in series, the assembly voltage-sharing capacitor is connected in parallel at two ends of a series branch of the thyristor stages connected in series, and a test voltage source is connected in series with a sampling resistor and then connected in parallel at two ends of the assembly voltage-sharing capacitor; the follower comprises an operational amplifier, a test voltage source is connected to the input positive end of the operational amplifier through a sampling resistor, the input negative end of the operational amplifier is connected with the output end, and then the test voltage source is connected to any position among a plurality of thyristor stages which are connected in series; the output end of the follower is in a high-impedance state. The value of the current flowing through the component voltage-sharing capacitor can be accurately calculated by collecting the voltages at the two ends of the sampling resistor, and the capacitance value of the component voltage-sharing capacitor is obtained according to the voltage and the current of the component voltage-sharing capacitor. The invention simplifies the testing process of the component voltage-sharing capacitor and improves the accuracy and the working efficiency.
Description
Technical Field
The invention relates to the technical field of high-voltage direct-current transmission converter valves, in particular to a circuit and a method for testing voltage-sharing capacitance of a high-voltage direct-current transmission converter valve assembly.
Background
The converter valve is an important element in a high-voltage direct-current transmission project and has important significance on safe operation of direct-current transmission. In order to meet the requirement of high voltage of the converter valve, the single converter valve is formed by serially connecting a plurality of thyristors, generally 6-15 thyristor stages are serially connected to form a valve assembly, then a plurality of valve assemblies form a valve tower, and each valve hall is provided with a plurality of valve towers. The distribution of stray capacitance in the valve tower is very complicated, and the stray capacitance can cause the imbalance of voltage distribution under the condition of a steep-wave-front voltage, particularly the imbalance of voltage between valve components, so that the valve components are designed with SF6 gas filled in the valve components, and the capacitance is a valve component voltage-equalizing capacitance of a few nanofarads.
According to the requirements of the maintenance standard DLT 273 and 2012 +/-800 kV extra-high voltage direct current equipment preventive test regulations of the converter valve, the parameter values of the voltage-sharing capacitors of the valve assemblies need to be detected regularly. However, as a single converter station has hundreds of valve assemblies, the measurement of the voltage-sharing capacitance parameters of the valve assemblies is carried out in the process of maintenance. The traditional method for testing the pressure-equalizing capacitance of the valve assembly mainly utilizes a universal meter, a bridge and the like to carry out direct testing, the method needs to dismantle an original circuit and carry out measurement one by one, the testing accuracy can be ensured, but the problems that the contact resistance of a connector exceeds the standard when the circuit connection is restored and the like are easily caused, and potential safety hazards exist. And the testing work steps are complicated, and the efficiency is very low.
Therefore, it is an urgent need to solve the problem of the art to provide a circuit and a method for testing the parameters of the voltage-sharing capacitor of the valve assembly accurately and quickly.
Disclosure of Invention
In view of the above, the invention provides a voltage-sharing capacitor test circuit and method for a high-voltage direct-current transmission converter valve assembly, which can simplify the test process of the voltage-sharing capacitor of the assembly by increasing a voltage source and designing a test circuit of the voltage-sharing capacitor of the assembly by using a follower and a sampling resistor, and improve the working efficiency and accuracy.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a voltage-sharing capacitor test circuit of a high-voltage direct-current transmission converter valve assembly, wherein the converter valve assembly comprises a plurality of thyristor stages connected in series, and assembly voltage-sharing capacitors are connected in parallel at two ends of a series branch of the plurality of thyristor stages connected in series. The test circuit comprises a test voltage source, a follower and a sampling resistor; wherein, the first and the second end of the pipe are connected with each other,
the test voltage source is connected with the sampling resistor in series and then connected to two ends of the component voltage-sharing capacitor in parallel;
the follower comprises an operational amplifier, the test voltage source is connected to the positive input end of the operational amplifier through a sampling resistor, the negative input end of the operational amplifier is connected with the output end, and then the test voltage source is connected to any position among the plurality of thyristor stages connected in series; the output end of the follower is in a high-impedance state.
Preferably, the test voltage source outputs a sinusoidal alternating voltage with adjustable frequency.
Preferably, the test voltage source comprises: the sine wave generator outputs an alternating voltage signal, and a sine alternating voltage is output through the signal regulator and the power amplifier.
Preferably, the sampling circuit further comprises a data acquisition circuit, and the data acquisition circuit acquires sampling voltages at two ends of the sampling resistor.
Preferably, the data acquisition circuit includes: the filtering amplifying circuit, the true effective value conversion circuit and the analog/digital conversion circuit are connected in sequence;
the sampling voltage is connected to a filtering and amplifying circuit to carry out high-frequency interference filtering and signal amplification; the DC signal output by the true effective value conversion circuit is input to an analog/digital conversion circuit, the analog/digital conversion circuit controls AD of a voltage channel and a current channel by a singlechip to carry out synchronous sampling, and each path of analog signal is converted into a digital signal.
Preferably, the device also comprises an industrial embedded mainboard which receives the sampling voltage at two ends of the sampling resistor and is communicated with the single chip microcomputer through a serial port to finish the calculation, storage and display of the voltage-sharing capacitance value of the component.
The invention also provides a test method of the voltage-sharing capacitor test circuit of the high-voltage direct-current transmission converter valve assembly according to the first aspect, wherein the capacitance value is calculated according to the voltage and the current of the voltage-sharing capacitor of the assembly: :
in the formula, U is the voltage across the component voltage-sharing capacitor, I is the current flowing through the component voltage-sharing capacitor, and ω is the frequency of the applied test voltage source. And I is the current at the two ends of the sampling resistor, and is obtained by sampling the voltage at the two ends of the sampling resistor/the resistance value of the sampling resistor.
Through the technical scheme, compared with the prior art, the invention has the beneficial effects that:
according to the invention, through circuit design, the output end of the voltage follower is in a high-resistance state, the test voltage source only forms a measurement loop with the component voltage-sharing capacitor, and the actual value of the component voltage-sharing capacitor can be calculated according to the voltage and current collected by the sampling resistor. The quick and accurate measurement can be realized without dismantling the lead of the voltage-sharing capacitor, the shutdown time of the valve assembly is reduced, and the working efficiency is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts;
FIG. 1 is a schematic diagram of a circuit connection structure of a converter valve assembly according to an embodiment of the present invention;
FIG. 2 is a circuit diagram for testing voltage-sharing capacitance of a HVDC converter valve assembly provided by an embodiment of the invention;
FIG. 3 is a block diagram of a converter valve assembly voltage-sharing capacitance test platform provided by an embodiment of the invention;
FIG. 4 is a schematic diagram illustrating the operation of a test voltage source according to an embodiment of the present invention;
fig. 5 is a schematic diagram of an operating principle of the voltage follower according to the embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The valve component is a basic electrical unit of the converter valve, each single valve is composed of a certain number of valve components in a mechanical structure, the structure of the valve component is shown in figure 1, each valve component is composed of a plurality of thyristor stages, each thyristor stage is composed of a damping capacitor, a damping resistor, a thyristor and a voltage-sharing capacitor, a valve component is composed of a plurality of thyristor stages and a saturation valve reactor connected in series, and the valve component further comprises a component voltage-sharing capacitor.
Because the voltage grade of the high-voltage direct-current transmission project is higher, the number of the thyristors in series connection is large, and the size of the converter valve body is larger. It is this reason that the non-uniformity of the dynamic voltage distribution on the converter valve modules and components due to the dispersion of the stray capacitance distribution is increased, and under the action of the steep front surge voltage, the dispersion of the stray capacitance distribution is further enhanced due to the high dv/dt, and the non-uniform distribution of the dynamic voltage is more obvious. And the component voltage-sharing capacitor can play a good voltage-sharing role when the valve is subjected to high-frequency impulse voltage.
Because the component voltage-sharing capacitor is connected in parallel at two ends of the thyristor level, one group of thyristor levels consists of a plurality of thyristors, and the capacitance value of the component voltage-sharing capacitor is generally several nanofarads. The capacitance of the thyristor-level damping loop is micro-farad level and is much larger than the capacitance of the component voltage-sharing capacitor, so that the component voltage-sharing capacitance is difficult to directly measure by using a capacitance meter. In order to accurate measurement subassembly voltage-sharing capacitance value, this patent adopts indirect measurement's method.
As shown in fig. 2, an embodiment of the present invention provides a voltage-sharing capacitor test circuit for a high-voltage direct-current transmission converter valve assembly, including a test voltage source, a follower, and a sampling resistor; the test voltage source is connected with the sampling resistor in series and then connected to two ends of the component voltage-sharing capacitor in parallel; the follower comprises an operational amplifier, a test voltage source is connected to the input positive end of the operational amplifier through a sampling resistor, the input negative end of the operational amplifier is connected with the output end, and then the test voltage source is connected to any position among a plurality of thyristor stages which are connected in series; the output end of the follower is in a high-impedance state.
In this embodiment, the connection of the output end of the operational amplifier to any position between the plurality of thyristor stages connected in series includes connection between the series nodes of every two thyristor stages, and does not include nodes at both ends of the series branch.
In this embodiment, as shown in fig. 5, the voltages of the input positive terminal and the output terminal of the follower are equal, and the current is equal to zero. The output end of the follower is in a high-resistance state, the test voltage source only forms a measurement loop with the component voltage-sharing capacitor, the output voltage of the voltage follower is basically the same as the input voltage, the voltage follower is in a high-resistance state for a front-stage circuit, and the voltage follower is in a low-resistance state for a rear-stage circuit, so that the front-stage circuit and the rear-stage circuit are isolated, and the output current of the test source only flows through the component voltage-sharing capacitor. And calculating the voltage and the current at two ends of the voltage-sharing capacitor of the component according to the voltage and the current acquired by the sampling resistor.
In one embodiment, the converter valve assembly voltage-sharing capacitance test platform is shown in fig. 3 and comprises 4 parts of a test voltage source, a data acquisition circuit, an industrial-grade embedded mainboard and a follower.
In one embodiment, the test voltage source outputs a sinusoidal alternating voltage with an adjustable frequency.
In this embodiment, the working principle of the test voltage source is as shown in fig. 4, and the single chip microcomputer controls the waveform generator to output an alternating voltage signal, and the alternating voltage signal is output through signal regulation and power amplification. The sine wave generating circuit adopts a precise high-frequency waveform generator MAX038, can generate accurate and standard sine alternating current signals, the frequency of output voltage can be respectively controlled by adjusting current, voltage or resistance, and the amplitude of the output voltage can be adjusted to a voltage value required by a test through a signal regulator. In the embodiment, the power amplification circuit adopts a high-power high-voltage DMOS tube TDA7293, in order to improve the output power, the power amplification device is connected with three power amplification tubes in parallel, and the power amplification device works in a master-slave mode, that is, all circuits from input to output of a master chip work, the front parts of the other two slave chips are shielded, and only the power output part of the rear stage works. In order to improve the precision of the test voltage, the precision of the output voltage is more accurate through readjustment of the voltage feedback signal.
In one embodiment, the data acquisition circuit acquires a sampled voltage across the sampling resistor.
In this embodiment, the data acquisition circuit includes a filtering and amplifying circuit, a true effective value conversion circuit, and an analog/digital conversion circuit, which are connected in sequence. Because the valve component voltage-sharing capacitor is only a few nanofarads, the flowing test current is small, and therefore a precision resistor is adopted to convert a current signal into a voltage signal. The sampling voltage is connected to a filtering and amplifying circuit to carry out high-frequency interference filtering processing and amplify the signal. The DC signal output by the true effective value conversion circuit is input to an analog/digital conversion circuit, the analog/digital conversion circuit controls AD of a voltage channel and a current channel by a single chip microcomputer to carry out synchronous sampling, each path of analog signal is converted into a digital signal, and the single chip microcomputer reads the digital signal.
In one embodiment, the industrial embedded mainboard receives the sampling voltage at two ends of the sampling resistor, and the industrial embedded mainboard is communicated with the single chip microcomputer through a serial port to complete calculation, storage and display of the voltage-sharing capacitance value of the component.
In this embodiment, the industrial embedded motherboard includes a microprocessor, a chipset, an LVDS (Low-Voltage Differential Signaling) interface, a cf (compact flash) card interface, a usb (universal Serial bus) interface, and a gpio (general Purpose Input output) interface. The mainboard is communicated with the single chip microcomputer through a serial port, the capacitance value of the assembly is calculated, stored and displayed, the amplitude and the frequency of a voltage source are tested, and human-computer interface interaction is achieved through the LVDS interface.
The embodiment of the invention also discloses a test method based on the voltage-sharing capacitor test circuit of the high-voltage direct-current transmission converter valve assembly, which comprises the following steps of:
in the formula, U is the voltage across the component voltage-sharing capacitor, I is the current flowing through the component voltage-sharing capacitor, and ω is the frequency of the applied test voltage source.
The testing voltage is applied to two ends of the assembly voltage-sharing capacitor, the current value flowing through the assembly voltage-sharing capacitor can be accurately calculated by collecting the voltage at two ends of the sampling resistor, and the assembly voltage-sharing capacitance value can be calculated by the formula (2) according to the voltage and the current value of the assembly voltage-sharing capacitor. The test result is stored in the computer readable storage medium and is displayed through the LCD display screen, and the test method is simple and easy to implement and has high working efficiency.
Compared with the traditional testing method adopting a universal meter, a bridge and the like, the testing process is quicker and more accurate, the capacitor lead needs to be detached in the traditional method, the wiring is recovered after the testing is finished, then the converter valve low-voltage test is carried out to confirm the good wiring, and the whole process needs about 2 hours. The method only needs about 10 minutes and does not need to carry out related tests on the converter valve.
The voltage-sharing capacitor test circuit and method for the high-voltage direct-current transmission converter valve assembly provided by the invention are described in detail, a specific example is applied in the test circuit to explain the principle and the implementation mode of the invention, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (7)
1. A voltage-sharing capacitor test circuit of a high-voltage direct-current transmission converter valve component comprises a plurality of thyristor stages connected in series, and component voltage-sharing capacitors are connected in parallel at two ends of serial branches of the thyristor stages connected in series; the device is characterized by comprising a test voltage source, a follower and a sampling resistor; wherein the content of the first and second substances,
the test voltage source is connected with the sampling resistor in series and then connected to two ends of the component voltage-sharing capacitor in parallel;
the follower comprises an operational amplifier, the test voltage source is connected to the positive input end of the operational amplifier through a sampling resistor, the negative input end of the operational amplifier is connected with the output end, and then the test voltage source is connected to any position among the plurality of thyristor stages connected in series; the output end of the follower is in a high-impedance state.
2. The voltage-sharing capacitor test circuit for the HVDC converter valve assembly according to claim 1, wherein the test voltage source outputs a sinusoidal AC voltage with adjustable frequency.
3. The HVDC converter valve assembly grading capacitance test circuit according to claim 2, wherein the test voltage source comprises: the sine wave generator outputs an alternating voltage signal, and a sine alternating voltage is output through the signal regulator and the power amplifier.
4. The voltage-sharing capacitance test circuit for the high-voltage direct-current transmission converter valve assembly according to claim 1, further comprising a data acquisition circuit, wherein the data acquisition circuit acquires sampling voltages across the sampling resistor.
5. The voltage-sharing capacitance test circuit for the HVDC converter valve assembly according to claim 4, wherein the data acquisition circuit comprises: the filter amplifying circuit, the true effective value conversion circuit and the analog/digital conversion circuit are connected in sequence;
the sampling voltage is connected to a filtering and amplifying circuit to carry out high-frequency interference filtering and signal amplification; the DC signal output by the true effective value conversion circuit is input to an analog/digital conversion circuit, the analog/digital conversion circuit controls AD of a voltage channel and a current channel by a singlechip to carry out synchronous sampling, and each path of analog signal is converted into a digital signal.
6. The voltage-sharing capacitance testing circuit of the high-voltage direct-current transmission converter valve assembly according to claim 4, further comprising an industrial-grade embedded main board which receives the sampling voltages at two ends of the sampling resistor and completes calculation, storage and display of the voltage-sharing capacitance value of the assembly through communication between a serial port and a single chip microcomputer.
7. A test method for a voltage-sharing capacitor test circuit of a high-voltage direct-current transmission converter valve assembly according to any one of claims 1-6, characterized in that a capacitance value is calculated according to the voltage and the current of a voltage-sharing capacitor of the assembly:
in the formula, U is the voltage across the component voltage-sharing capacitor, I is the current flowing through the component voltage-sharing capacitor, and ω is the frequency of the applied test voltage source.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116224043A (en) * | 2023-05-04 | 2023-06-06 | 晶艺半导体有限公司 | Chip voltage equalizing test system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116224043A (en) * | 2023-05-04 | 2023-06-06 | 晶艺半导体有限公司 | Chip voltage equalizing test system |
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