CN204359923U - A kind of novel high voltage direct current generator calibration equipment - Google Patents

Abstract

The utility model discloses a novel calibration device for a direct current high voltage generator, which comprises a ripple measurement sampling unit, a load resistance unit and a voltage standard sampling unit. The load resistance unit includes load resistance and sampling resistance connected in series, and the voltage standard sampling unit includes a standard voltage divider. The ripple measurement sampling unit, load resistance unit and voltage standard sampling unit are all connected by a digital voltmeter and a computer. Connected, the high voltage emitted by the DC high voltage generator is converted into a low voltage suitable for the measurement range of the digital voltmeter through the voltage divider of the ripple measurement sampling unit, the load resistance unit and the voltage standard sampling unit, for the digital voltmeter to collect and transmit corresponding signals to the computer. The calibration device has a high degree of automation, convenient and clear operation, which greatly simplifies the testing process of the test personnel, reduces labor intensity and improves work efficiency.

Description

A New Calibration Device for DC High Voltage Generator

technical field

The utility model relates to a novel calibrating device for a DC high voltage generator.

Background technique

DC high-voltage generators are widely used in electric power departments, industrial and mining, metallurgy, steel and other enterprise power departments to conduct DC withstand voltage tests and DC leakage current tests on high-voltage electrical equipment such as zinc oxide arresters, power cables, transformers, generators, and high-voltage switches. In order to operate safely in the power system, the power equipment must be periodically tested every year to confirm whether it can operate safely. One of the high-voltage test equipment for testing is a DC high-voltage generator. According to the requirements of the corresponding specifications of the power system, the DC high-voltage generator (including other related high-voltage test equipment) must be sent to a qualified testing department for periodic calibration every year.

Among them, the zinc oxide arrester has high requirements on the function and performance of the DC high voltage generator. That is to say, there are corresponding requirements for the accuracy of voltage indication and current indication, AC ripple and capacity when the DC high voltage generator is working.

The zinc oxide arrester is installed at the incoming end of the high-voltage line of the substation. Its function is to protect the power equipment from damage when the operating line is struck by lightning, or when the operating line generates internal overvoltage for some reason.

Zinc oxide surge arrester is composed of zinc oxide valve plate, which has good nonlinear characteristics. The zinc oxide surge arrester made of it has low residual voltage, large flow capacity, fast response time, no power frequency freewheeling, no series gap, and can reduce the The insulation level of the protective equipment. Therefore, it is widely used in the power system, which greatly improves the security of the power system and produces huge economic benefits. However, after on-site operation, it was found that the zinc oxide arrester tends to age due to long-term exposure to power frequency voltage, impulse voltage, and internal moisture, which destroys its insulation properties. The performance is that the increase of leakage current causes thermal collapse, which will lead to damage or explosion of the zinc oxide arrester in severe cases, and then cause large-scale power outages. Therefore, the leakage current of the zinc oxide arrester must be periodically detected to ensure its safe operation.

When the arrester leaves the factory, the installation is completed, or after a period of operation, according to the "Electrical Installation Engineering Electrical Equipment Handover Test Standard" and the "Electrical Equipment Preventive Test Regulations", the critical operating voltage U _1mA and Leakage current test under 0.75U _1mA DC voltage.

Purpose of the test:

1. The purpose of measuring the critical operating voltage U _1mA at DC 1mA is to check whether the interior is damp;

2. The purpose of measuring the leakage current under 0.75U _1mA DC voltage is whether its long-term allowable working current meets the regulations. The equipment for the above test is a DC high voltage generator.

When inspectors calibrate the DC high voltage generator, the guidance document based on it is DL-T848.1-2004 "General Technical Conditions for High Voltage Test Device Part I DC High Voltage Generator". The standard stipulates that for the basic test of the DC high voltage generator to be calibrated, it must be verified at different voltages, currents, ripples under different voltages, and rated voltage and current capacity, that is, the test personnel need to repeatedly operate the DC high voltage generator. The booster device provides multiple test points for the calibration device to measure. At the same time, during the calibration process, the test personnel must measure one by one according to the calibration point requirements stipulated in the standard, and record the measurement data at the same time to form an original record, calculate the error, and issue a calibration certificate. The whole verification process is cumbersome, the work efficiency is low, and it is not suitable for the development of the power system.

Another problem in the existing calibration device is that as the voltage level of the power system increases, the output voltage of the test equipment will increase, and the rated voltage of the corresponding high-voltage voltage divider used for sampling must also meet the requirements. From a technical point of view, the withstand voltage of the high-voltage voltage divider is increased, and the voltage coefficient of the voltage division ratio is difficult to meet the calibration requirements during manufacture. If the requirements are to be met, many hardware compensation measures must be taken, which will inevitably increase the volume and weight of the voltage divider, increase the cost correspondingly, and reduce the cost performance. (Note: The voltage division ratio refers to the ratio of the high voltage to the low voltage; the voltage coefficient refers to the degree to which the voltage division ratio is consistent under different voltages).

With the development of society, the society's demand for electricity is increasing, and the power system needs to build more substations and increase a large number of power equipment accordingly. The increase in power equipment has also contributed to the increase in the possession of DC high voltage generators. A large number of DC high-voltage generators have to be sent to the testing department for weekly inspections every year, which greatly increases the workload of the testing personnel and is overwhelmed. Therefore, inspectors urgently need an intelligent inspection device that is fast, accurate, and can improve detection efficiency.

Utility model content

In order to solve the deficiencies of the existing technology, the utility model discloses a new type of DC high voltage generator calibration device, the calibration device is controlled by a microcomputer, and uses a virtual instrument interface and man-machine dialogue to set the measured parameters, Calibration is a new type of calibration device that not only ensures long-term stability and reliability of calibration, but also has intelligent features.

In order to achieve the above object, the concrete scheme of the present utility model is as follows:

A new type of DC high-voltage generator calibration device, including a ripple measurement sampling unit, a load resistance unit and a voltage standard sampling unit, the ripple measurement sampling unit includes a high-voltage filter capacitor and a resistor divider connected in series, and the load resistance The unit includes a load resistor and a sampling resistor connected in series, the voltage standard sampling unit includes a standard voltage divider, the ripple measurement sampling unit, the load resistance unit and the voltage standard sampling unit are all connected to the computer through a digital voltmeter, and the DC high voltage generator The high voltage emitted is converted into a low voltage suitable for the measurement range of the digital voltmeter through the voltage divider of the ripple measurement sampling unit, the load resistance unit and the voltage standard sampling unit, for the digital voltmeter to collect corresponding signals and send them to the computer.

The ripple measurement sampling unit, the load resistance unit and the voltage standard sampling unit are powered by a high voltage power supply.

The computer is connected to the digital voltmeter through a USB connection.

Working principle: When calibrating the DC high voltage generator, divide 0~ _UN (rated voltage) or 0~ _IN rated current into several measuring points, such as ten measuring points, according to the requirements of relevant regulations. During the inspection, the DC high-voltage generator is manually operated to gradually increase the voltage (take the DC voltage as an example) to the rated value, and then manually record the measurement data point by point on the pre-printed form, calculate the error, and write the test report.

When verifying the DC high-voltage generator in this application, the preconditions without repeated operations are that the DC high-voltage generator itself has an automatic boost function, and it must have a peripheral control interface and an open communication protocol. Under this premise, the computer in the calibration device can control the DC high voltage generator to automatically boost the voltage under the set program, and there is no need to manually increase the voltage repeatedly.

Of course, DC high-voltage generators without automatic boost function can only boost the voltage manually, and then automatically record measurement data, calculate errors, and write test reports. At present, the above two types of products are produced by manufacturers.

The measurement principle of the calibration device is based on the voltage, current, and ripple voltage (ripple) analogs given by the ripple voltage divider, the load resistance sampling terminal and the standard voltage divider when the DC high voltage generator has raised the high voltage. Under the operation control of the microcomputer interface, it will be sent to the input terminals of three digital voltmeters respectively, and the digital voltmeter will convert the analog quantity collected into digital quantity through the A/D in the meter. The digital quantity is uploaded to the PC through the serial port output of the digital voltmeter in the form of data flow. The PC controls the digital quantity through the corresponding interface, data processing software, error calculation software, and report forming software, and completes the original records of measurement and testing, certificates or reports standardized processing, storage, output and printing.

The beneficial effects of the utility model:

The DC high voltage generator is an important test equipment to assess whether the power equipment can operate normally, and the accuracy of its value directly affects the safe operation of the power equipment. The DC high voltage generator calibration device is a measuring instrument used to check whether the voltage and current limit error of the DC high voltage generator can meet the accuracy requirements, and whether the ripple and capacity can meet the requirements. The calibration device adopts microcomputer control, uses virtual instrument interface, and man-machine dialogue to set and calibrate the measured parameters, which not only ensures long-term stability and reliability of calibration, but also is a new type of calibration device with intelligent features.

Its advantages boil down to:

1) Microcomputer control, use the virtual instrument interface, man-machine dialogue to set the relevant calibration parameters, and automatically measure.

2) This verification device realizes seamless connection to 3 multimeters through the Labview platform, and the data collected by it can be uploaded to the host computer software system at any time.

3) The calibration device is extremely convenient for correcting the voltage coefficient and error of the sampling unit of the high voltage divider. The technical difficulty of manufacturing is reduced, the volume and weight are reduced, and the cost performance is improved.

4) The calibration device has a high degree of automation, convenient and clear operation, which greatly simplifies the testing process of the test personnel, reduces labor intensity and improves work efficiency.

Description of drawings

Fig. 1 is the schematic circuit diagram of the utility model.

Detailed ways:

Below in conjunction with accompanying drawing, the utility model is described in detail:

As shown in Figure 1, the first column on the left in the figure is the tested DC high voltage generator, which raises the voltage to different calibration points according to the specification requirements for testing equipment to measure.

1) Ripple measurement

The second column on the left in the figure is the ripple measurement sampling unit, which consists of a high-voltage filter capacitor and a resistor divider. When working, the filter capacitor filters out the pulsating component in the DC high voltage and sends it to the end of the resistor divider. The resistor divider reduces the pulsating voltage U ₁ to U ₂ to within the range of the digital voltmeter. Its calculation formula is:

Ripple component = U ₁ /U×100%

Among them: U ₁ =U ₂ ×k ₁ , k ₁ —voltage division ratio of resistor divider U—DC high voltage value

2) Capacity

The third column on the left in the figure is the load resistance unit, which loads the DC high voltage generator through the load resistance, and the current value I obtained by the load resistance _R1 is converted into a voltage proportional to the current value through the standard resistance _R1 , multiply the reference voltage U ref obtained by the second digital voltmeter with the reference voltage U _ref obtained by the third digital voltmeter, _and calculate the capacity

The calculation formula is: P＝U ₃ ×U _ref ＝I×R ₁ ×U _ref

Among them: P—capacity of DC high voltage generator R ₁ —scale coefficient with fixed value

3) Current indication

The current indication value refers to the current indication value generated by the ammeter on the DC high voltage generator that needs to provide current to the load when the DC high voltage generator raises the voltage.

Current indication measurement data acquisition: When the DC high voltage generator rises to a voltage value, the corresponding DC high voltage generator ammeter will have a current indication value, and the same current will flow through the load resistor in the third column on the left in the figure. This current is converted into a voltage proportional to the current value through the standard resistor _R1 , which is obtained by the second digital voltmeter.

The high end of the sampling unit for ripple measurement in the second column on the left in the figure is a filter capacitor without a DC channel. The fourth column on the left in the figure is the standard voltage divider, and the current it consumes has been corrected in the error processing software.

In the actual verification, there is a table compiled on the computer virtual interface, as shown in the following example:

Indication(mA) Standard value (measured value) mA error(%) 1 1.0045 -0.45 2 2.0078 -0.39 3 3.0095 -0.32 4 4.0123 -0.31

5 5.0152 -0.30

Set the voltage of the DC high voltage generator so that the ammeter indicates 1mA, click the OK button on the interface, and the measured value will automatically enter the first row and second column, such as 1.0045mA. 2 ~ 5mA and so on.

Of course, there is an error between the indicated value of the ammeter of the DC high voltage generator and the measured value (the value obtained by the second digital voltmeter), which is the work to be done in the subsequent error processing software.

The current indication value I _x error of the DC high voltage generator is calculated by the following formula:

Current indication error=(I _x –I)/I×100%

I _x : DC high voltage generator ammeter indication value

I: The current measurement value of the DC high voltage generator, that is, the value obtained by the second digital voltmeter

4) Voltage indication

Voltage indication refers to the indication value of the voltmeter on the DC high voltage generator when the voltage is raised.

Data acquisition of voltage indication measurement: When the DC high voltage generator rises to a voltage value, a voltage is also applied to the standard voltage divider in the fourth column on the left in the figure. This voltage is divided by a standard voltage divider and converted into a voltage suitable for the range of the voltmeter, which is obtained by the third digital voltmeter. The voltage value U _ref obtained by it is a standard factor for calculating the magnitude error of voltage and current, and the size of ripple and capacity.

In the actual verification, there is a table compiled on the computer virtual interface, as shown in the following example:

Indication (kV) Standard value (measured value) kV error(%) 50 50.23 -0.46 100 100.41 -0.41 150 150.62 -0.41 200 200.85 -0.42 250 250.91 -0.36

Set the voltage of the DC high-voltage generator so that the voltmeter indicates 50kV, click the OK button on the interface, and the measured value will automatically enter the first row and second column, such as 50.23kV. 100 ~ 250kV and so on.

Of course, there is an error between the indicated value of the DC high voltage generator voltmeter and the measured value (the value obtained by the third digital voltmeter), which is the work to be done in the subsequent error processing software.

It calculates the voltage indication value U _x error of the DC high voltage generator by the following formula

Voltage indication error = (U _x –U _ref )/U _ref ×100%

U _x : DC high voltage generator ammeter indication value

U _ref : the voltage measurement value of the DC high voltage generator, that is, the value obtained by the third digital voltmeter.

The calibration device adopts microcomputerized management, the system is based on the windows xp operating system, and the software adopts the virtual instrument labview8.5 version. Labview (Laboratory Virtual instrument Engineering) is a graphical programming language, standard data acquisition and instrument control software, you can easily build your own virtual instrument, and its graphical interface makes the programming and use process lively and interesting. Through the operation control of the microcomputer interface, the calibration device realizes the acquisition, transmission, storage, and processing of measurement data, and automatically standardizes, stores, and outputs the records, certificates, and reports of measurement, calibration, verification, and testing, and improves work efficiency.

The calibration device is very convenient to correct the voltage coefficient and error of the sampling unit of the high-voltage voltage divider: the voltage division ratio refers to the ratio of the high voltage to the low voltage, which is a constant, that is, k=U1/U2 (k is the voltage division ratio)

The voltage coefficient refers to the degree to which the voltage division ratio is consistent under different voltages. It is dimensionless and measured by error.

A resistive divider consists of resistors whose voltage coefficient is caused by the manufacturing process and whose resistance value changes when different operating voltages are applied. A change in the resistance value also affects the voltage coefficient of the resistor divider. Therefore, after the resistor divider is manufactured, its voltage coefficient has been determined, and it cannot be changed from the perspective of hardware.

In actual operation, before calibrating the DC high-voltage generator, first calibrate the voltage division ratio error of the resistor divider at different voltages from low to high, and according to the error of the voltage division ratio of each voltage calibration point and the set standard voltage division ratio (Example k=1000) determines the correction value. Then, according to the correction value, it is corrected by software to achieve the correction of the voltage coefficient.

Specific method: Click the parameter setting bar in the detection software, and three coefficient modification tables of DC voltage, DC current and AC voltage (ripple) will be displayed. These three coefficient modification tables correspond to three 6-digit 1/2 digital multimeters, which measure DC voltage, DC current (current-to-voltage conversion) and AC voltage (ripple). Then according to the measured partial pressure ratio error, it is very convenient to correct it. At this time, the coefficient is corrected to offset the error and make the measured value more accurate.

The measurement principle of the calibration device is based on the voltage, current, and ripple voltage (ripple) analog quantities given by the ripple voltage divider, load resistance and standard voltage divider. Under the operation control of the microcomputer interface, they will be sent to three The input terminal of the digital voltmeter, the digital voltmeter converts the acquired analog quantity into a digital quantity through the A/D in the meter. The digital quantity is uploaded to the PC through the serial port output of the digital voltmeter in the form of data flow. The PC controls the data processing software, error calculation software, and report forming software through the corresponding interface to complete the standardization, storage, output and printing of the original records of measurement and testing, certificates or reports.

1) The main interface is used to enter the following information

a) Relevant information of the tested product, such as the entrusting party (submitting unit), address of the entrusting party, name of the tested product, model specification, serial number, manufacturer, etc.;

b) Sending and receiving information of the tested product, such as the date of receiving the sample, serial number of sending and receiving, entrusted document number, etc.;

c) Relevant information during calibration, such as report number, calibration/test date, calibration/test environment conditions, calibration/tester, verifier, etc.;

d) A statement of the calibration/test results of the test article.

Specific operation: press the "Add" button, after entering the above information, press the "Save" button to save the data in the database. If you make a mistake, you can press the "Modify" or "Delete" button to modify and delete.

2) Input of standard and measuring instrument information

a) Technical documents (standards) used during calibration/testing;

b) Measuring instruments used in calibration/testing and records of their usage.

When the measuring instrument used in a certain calibration/test is within one week before the expiration date, the color corresponding to the date in the "certificate expiration date" column will automatically display red, and at the same time, a warning that it cannot be used will be displayed in "Use/No".

Specific operation: Press the "Appliance Add" button to enter complete information, press the "Save" button to save the data to the database, if the input is wrong, please select the record to be modified and click the "Modify" or "Delete" button to realize the data modification and deletion.

3) Input of calibrator settings and calibration/test item information

a) Select the multimeter used for DC voltage, DC current, and AC voltage (ripple voltage).

b) The voltage division ratio of the DC standard voltage divider, the resistance value of the DC standard resistance, and the voltage division ratio of the resistance voltage divider in the ripple voltage measuring device.

c) Visual inspection results and insulation resistance measurement results of the tested product.

This window is used to test or calibrate the following parameters:

d) Ripple coefficient of the tested product;

e) The measured capacity of the tested product;

4) High pressure sampling unit

This part of the work is controlled by the PC, and it starts working after completing the input of the first 3 interface information;

5) High voltage conversion part

The function of this part is to convert the high voltage emitted by the DC high voltage generator into a low voltage suitable for the measurement range of the digital voltmeter through three unit voltage dividers for the digital voltmeter to collect corresponding signals.

6) Digital Voltmeter

This part uses Agilent 34401A digital multimeter for signal acquisition.

When working, the signal is sampled through the A/D in the meter, and the collected analog quantity is converted into the corresponding digital quantity, and uploaded to the PC through the serial port.

7) Data processing of PC

The data stream uploaded by the PC will be measured and calculated according to the control requirements of each corresponding interface with software, and the report forming software will complete the report/record preview, storage and printing

This application completes the four parameters of voltage indication value, current indication value, AC ripple and capacity at one time to collect, transmit, store, process, automatically generate certificates, automatically save and save historical records; use software to correct high-voltage dividers The voltage coefficient and error of the sampling unit; it can be controlled remotely to transmit the data to the background.

Complete these four parameter methods: the first meter samples the resistor divider U2 at the lower end of the ripple voltage divider; the second meter samples the standard resistor at the lower end of the load resistor, and reads the voltage U3 proportional to the current; The third table reads the reference voltage Uref parameter by sampling the standard voltage divider. Then determine the magnitude error of voltage and current, as well as the size of ripple and capacity according to the corresponding algorithm.

The so-called one-time completion of the measurement refers to a step-up process of the DC high voltage generator from zero to the rated voltage to complete the measurement of four parameters. That is to say, when the voltage indication value is reached during boosting, the voltage measurement value is determined. The measured current value is determined when the indicated current value is reached. Simultaneously determine ripple and capacitance measurements.

Claims (3)

1. a novel high voltage direct current generator calibration equipment, it is characterized in that, comprise ripple and measure sampling unit, pull-up resistor unit and voltage standard sampling unit, described ripple is measured sampling unit and is comprised the high-voltage filtering capacitor and resitstance voltage divider that are in series, pull-up resistor unit comprises the pull-up resistor and sample resistance that are in series, voltage standard sampling unit comprises standard voltage divider, described ripple measures sampling unit, pull-up resistor unit and voltage standard sampling unit are all connected with computing machine by digital voltmeter, the high pressure that high voltage direct current generator sends measures sampling unit by ripple, the voltage divider of pull-up resistor unit and voltage standard sampling unit converts the low pressure that range measured by applicable digital voltmeter to, computing machine is sent to for the corresponding signal of digital voltmeter collection.

2. a kind of novel high voltage direct current generator calibration equipment as claimed in claim 1, is characterized in that, described ripple is measured sampling unit, pull-up resistor unit and voltage standard sampling unit and powered by high-voltage power supply.

3. a kind of novel high voltage direct current generator calibration equipment as claimed in claim 1, is characterized in that, computing machine is connected with digital voltmeter by USB line.