CN107356833B - A control and measurement circuit of a power frequency freewheeling test device - Google Patents

Abstract

The invention provides a control and measurement circuit of a power frequency freewheeling test device, which belongs to the field of control and measurement of electric equipment. The control measurement circuit includes: a primary side measurement circuit, a signal conditioning circuit, a control circuit, and a controller; the primary side measurement circuit is used to collect measurement signals from the primary side circuit, and transmit the measurement signals to the signal conditioning circuit; the signal conditioning circuit is used for The measurement signal is subjected to signal conditioning and digital-to-analog conversion, and the converted measurement signal is transmitted to the controller; the controller is used to output a control signal to the control circuit according to the converted measurement signal, and the control circuit triggers the surge voltage in the primary side circuit to occur The device generates an impulse overvoltage; among them, the control circuit, the signal conditioning circuit and the controller are powered by one voltage respectively, and the voltages are isolated from each other. The invention can effectively prevent the impact overvoltage generated by the impulse voltage generator in the primary side circuit from causing damage to the control and measurement circuit of the power frequency freewheeling test device.

Description

A control and measurement circuit of a power frequency freewheeling test device

technical field

The invention relates to the field of electric equipment control and measurement, and more particularly, relates to a control and measurement circuit of a power frequency freewheeling test device.

Background technique

Power surge arresters are widely used in power supply and railway power systems to guide lightning current to the ground, thereby suppressing the impact of lightning wave overvoltage on power users. At present, the commonly used electrical surge arresters are zinc oxide arresters. Since the quality of the power arrester directly affects the lightning protection performance of the power system, it is of great significance to carry out experimental research on the current recovery characteristics of the zinc oxide arrester under the action of lightning waves, that is, to carry out the power frequency freewheeling test of the arrester. Important engineering practical value.

Carrying out the power frequency freewheeling test of the arrester needs to realize the joint pressurization of power frequency and impulse. Compared with the single power frequency and impulse voltage generator, the power frequency freewheeling test device requires the impulse overvoltage to be able to withstand any power frequency AC voltage. One point superposition requires higher control precision. At the same time, due to the high amplitude and steepness of the impulse voltage, the impulse overvoltage superimposed on the industrial frequency power supply may cause damage to the industrial frequency voltage source. Therefore, the reliability and stability requirements of the power frequency freewheeling test device are also higher.

In the related art, a control and measurement circuit of a power frequency freewheeling test device is provided, the power frequency power supply of which uses an RLC oscillating circuit to generate a power frequency voltage. Such a power frequency freewheeling test device may not always be able to generate resonance in the test, and the oscillation frequency is not necessarily 50Hz power frequency, resulting in a large randomness in this type of power frequency freewheeling test. In addition, according to the IEC (International Electro technical Commission, International Electrotechnical Commission) standard, most of the existing power frequency freewheeling test devices use grid connection test transformers to generate power frequency voltages, impulse voltage generators to generate impulse overvoltages, power frequency power supplies and Impact ball gaps are used to isolate the impact power sources. During the test of this type of power frequency freewheeling test device, due to the superposition of the impulse overvoltage between the control circuit, the measurement circuit and the power supply and the AC power supply, it is very likely to cause great damage to the control and measurement equipment of the power frequency freewheeling test device .

Contents of the invention

The present invention provides a control measurement circuit of a power frequency freewheeling test device which overcomes the above problems or at least partly solves the above problems.

The control and measurement circuit of the power frequency freewheeling test device includes: a primary measurement circuit, a signal conditioning circuit, a control circuit and a controller;

The primary-side measurement circuit is used to collect measurement signals from the primary-side circuit, and transmit the measurement signals to the signal conditioning circuit; the signal conditioning circuit is used to perform signal conditioning and digital-to-analog conversion on the measurement signals, and transmit the converted measurement signals to the controller; The controller is used to output a control signal to the control circuit according to the converted measurement signal, and the control circuit triggers the impulse voltage generator in the primary side circuit to generate an impulse overvoltage; among them, the control circuit, the signal conditioning circuit and the controller are respectively controlled by a circuit Voltage power supply, each voltage is isolated from each other.

Wherein, the control measurement circuit also includes a first photoelectric isolation module; the primary side measurement circuit is used to transmit the measurement signal to the first photoelectric isolation module, and the first photoelectric isolation module is used to photoelectrically isolate the measurement signal, and the measurement after photoelectric isolation The signal is passed to the signal conditioning circuit.

Wherein, the control measurement circuit also includes a second photoelectric isolation module; the control circuit is used to output a control signal to the second photoelectric isolation module according to the converted measurement signal; the second photoelectric isolation module is used to photoelectrically isolate the control signal, and to control The circuit outputs the control signal after photoelectric isolation.

Among them, the measurement signal includes the power frequency voltage signal, the voltage signal at both ends of the test product, and the current signal flowing through the test product; the primary side measurement circuit includes a resistance-capacitance voltage divider, a capacitance voltage divider, and a Rogowski coil. The power frequency voltage signal, the capacitive voltage divider is used to measure the voltage signal at both ends of the test object, and the Rogowski coil is used to measure the current flowing through the test object.

Among them, the control circuit, signal conditioning circuit and controller are powered by the preset power supply; the preset power supply is connected to the isolation transformer, and multiple voltages are output to the control circuit, signal conditioning circuit and controller through the isolation transformer, and the control circuit, signal conditioning circuit and control circuit The devices respectively correspond to a single voltage.

Wherein, the preset power supply is an uninterruptible power supply.

Among them, the primary side circuit includes a power frequency AC voltage source and an impulse voltage generator; the power frequency AC voltage source, the product under test and the impulse voltage generator are connected in parallel.

Among them, the power frequency AC voltage source includes a voltage regulator and a test transformer; the voltage regulator and the test transformer are connected in parallel.

The beneficial effect brought by the technical scheme proposed by the application is:

First of all, by isolating the control circuit, signal conditioning circuit and each branch voltage corresponding to the controller, it can effectively prevent the impulse overvoltage generated by the impulse voltage generator in the primary side circuit from causing damage to the control circuit, thereby effectively preventing Cause damage to the control and measurement equipment of the power frequency freewheeling test device.

Secondly, since it is possible to control the joint pressurization of the power frequency power supply and the impulse power supply, and measure the outlet voltage of the test transformer and the voltage and current applied to the test object, it is possible to evaluate the ability of the arrester equipment to extinguish the power frequency arc under the action of lightning waves.

In addition, because the primary side measurement circuit uses a voltage divider to measure the power frequency voltage and the voltage across the tested product; uses a Rogowski coil to measure the current flowing through the tested product. The voltage and current signals measured by the voltage divider and the Rogowski coil are transmitted to the signal conditioning and A/D conversion circuit after being photoelectrically isolated, and the voltage and current are converted into digital quantities and then transmitted to the controller, which can effectively prevent electromagnetic interference problems Distortion of the measurand brought about.

Finally, because the trigger conduction time of the impulse voltage generator can be calculated according to the measured power frequency voltage signal and the conduction phase angle input by the user, and the relay triggers the conduction of the impulse voltage generator, so that the impulse and power frequency voltage are within Arbitrary phase superposition, and then realize joint pressurization.

Description of drawings

Fig. 1 is a schematic structural diagram of a control measurement circuit of a power frequency freewheeling test device according to an embodiment of the present invention;

2 is a schematic structural diagram of a signal conditioning circuit according to an embodiment of the present invention;

3 is a schematic structural diagram of a control circuit according to an embodiment of the present invention;

4 is a schematic structural diagram of a primary-side measurement circuit according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a preset power supply according to an embodiment of the present invention;

FIG. 6 is a schematic flowchart of a synchronization trigger algorithm according to an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a primary side circuit according to an embodiment of the present invention.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

In a specific embodiment, the present invention is further described in conjunction with the accompanying drawings. Referring to FIG. 1 , FIG. 1 shows a control and measurement circuit of a power frequency freewheeling test device. The control and measurement circuit includes: a primary side measurement circuit 101 , a signal conditioning circuit 102 , a control circuit 103 and a controller 104 .

The primary-side measurement circuit 101 is used to collect measurement signals from the primary-side circuit, and transmit the measurement signals to the signal conditioning circuit 102; the signal conditioning circuit 102 is used to perform signal conditioning and digital-to-analog conversion on the measurement signals, and transmit the converted measurement signals to The controller 104; the controller 104 is used to output a control signal to the control circuit 103 according to the converted measurement signal, and the control circuit 103 triggers the impulse voltage generator in the primary side circuit to generate an impulse overvoltage; wherein, the control circuit 103, The signal conditioning circuit 102 and the controller are respectively powered by one voltage, and each voltage is isolated from each other.

Among them, after the measurement signal transmitted by the primary side measurement circuit 101 is transmitted to the signal conditioning circuit 102 through an optical fiber, the signal conditioning circuit 102 can first convert the received optical signal into a secondary side electrical signal, and perform operational amplification and level conditioning. After the signal conditioning process, it can be transmitted to the A/D (analog-to-electricity) conversion circuit. After the A/D conversion circuit converts the analog signal into a digital signal, it can be transmitted to the control circuit on the computer side for processing. Wherein, the signal conditioning circuit 102 is a secondary side signal conditioning circuit, and FIG. 2 is a schematic structural diagram of the signal conditioning circuit 102 .

The control and measurement circuit of the power frequency freewheeling test device provided by the embodiment of the present invention can effectively prevent the impact in the primary side circuit by isolating each branch voltage corresponding to the control circuit 103, the signal conditioning circuit 102 and the controller 104 from each other. The impulse overvoltage generated by the voltage generator causes damage to the control circuit 103, thereby effectively preventing damage to the control and measurement equipment of the power frequency freewheeling test device.

As an optional embodiment, the control measurement circuit also includes a first photoelectric isolation module 105; the primary side measurement circuit 101 is used to transmit the measurement signal to the first photoelectric isolation module 105, and the first photoelectric isolation module 105 is used to measure The signal is photoelectrically isolated, and the photoelectrically isolated measurement signal is transmitted to the signal conditioning circuit 102 .

Among them, the photoelectric isolation module is a new device composed of semiconductor tube sensitive devices and light-emitting diodes. Its main function is to achieve insulation isolation when electrical signals are transmitted, input and output. In addition, when the signal is transmitted in one direction, the photoelectric isolation module can achieve no feedback effect, and has the characteristics of strong anti-interference and fast response speed. When the photoelectric isolation module is working, the input signal is usually added to the input terminal to make the luminescent tube emit light. The photosensitive device outputs photocurrent under the magneto-optical radiation, so as to realize the double conversion of the electro-optical point.

The measurement signal is photoelectrically isolated by the first photoelectric conversion module 105, so that the output terminal of the primary side measurement circuit 101 and the input terminal of the signal conditioning circuit 102 are electrically isolated, that is, the output measurement signal has no influence on the input terminal of the signal conditioning circuit 102 , enhance the anti-interference ability of the measurement signal, and improve the transmission efficiency of the measurement signal.

As an optional embodiment, the control measurement circuit also includes a second photoelectric isolation module 106; the control circuit 103 is used to output a control signal to the second photoelectric isolation module 106 according to the converted measurement signal; the second photoelectric isolation module 106 is used for In order to photoelectrically isolate the control signal, the photoelectrically isolated control signal is output to the control circuit 103 .

The control signal is photoelectrically isolated by the second photoelectric conversion module 106, so that the output terminal of the control circuit 103 and the input terminal of the controller 104 are electrically isolated, that is, the output control signal signal has no influence on the input terminal of the controller 104, which enhances The anti-interference ability of the measurement signal improves the transmission efficiency of the control signal.

In addition, after the control signal is transmitted to the second photoelectric isolation module 106 by way of data line transmission, photoelectric isolation can be performed. The control signal after optical isolation can be transmitted to the controller 104 through optical fiber. After receiving the control signal, the controller 104 can generate a corresponding control level according to the instruction from the computer terminal, so as to control the surge voltage generator to charge or trigger the discharge of the surge capacitor to generate the surge overvoltage. Wherein, the structure of the control circuit 103 may be as shown in FIG. 3 .

As an optional embodiment, the measurement signal includes a power frequency voltage signal, a voltage signal at both ends of the test object, and a current signal flowing through the test object; the primary side measurement circuit 101 includes a resistance-capacitance voltage divider, a capacitance voltage divider, and a Rogowski coil. The resistance-capacitance voltage divider is used to measure the power frequency voltage signal, the capacitance voltage divider is used to measure the voltage signal at both ends of the tested product, and the Rogowski coil is used to measure the current flowing through the tested product.

Specifically, through the pulse capacitor voltage divider in the primary-side measurement circuit 101 , the voltage signal V1 at both ends of the DUT can be measured. The power frequency voltage signal V2 can be measured through the resistance-capacitance voltage divider in the primary-side measurement circuit 101 . The current signal i flowing through the DUT can be measured through the Rogowski coil in the primary side measurement circuit 101 . After measuring the power frequency voltage signal V2, the voltage signal V1 at both ends of the DUT and the current signal i flowing through the DUT, the above three signals can be used as measurement signals, and the measurement signals can be converted into The optical signal is transmitted to the signal conditioning circuit 102, which is not specifically limited in this embodiment of the present invention. As shown in Figure 4, the first picture on the left in Figure 4 is a schematic structural diagram of a Rogowski coil, the middle picture in Figure 4 is a structural schematic diagram of a pulse capacitor voltage divider, and the right picture in Figure 4 is a resistance-capacitance voltage divider Schematic diagram of the structure.

As an optional embodiment, the control circuit 103, the signal conditioning circuit 102, and the controller 104 are powered by a preset power supply; the preset power supply is connected to an isolation transformer, and the output signal is output to the control circuit 103, the signal conditioning circuit 102, and the controller 104 through the isolation transformer. For multiple voltages, the control circuit 103 , the signal conditioning circuit 102 and the controller 104 respectively correspond to a single voltage.

Specifically, the preset power supply can be located on the secondary side, that is, the secondary power supply in FIG. 1 . The preset power sources corresponding to the control circuit 103 , the primary-side measurement circuit 101 and the controller 104 are isolated from the primary-side power grid. The preset power supply outputs 220V AC voltage and is connected to an isolation transformer. The primary winding of the isolation transformer and each secondary winding are isolated from each other. The preset power supply can output multiple power supplies after passing through the secondary winding of the isolation transformer, so as to provide one voltage for the control circuit 103 , the primary side measurement circuit 101 and the controller 104 respectively. Specifically, the multi-channel power supply output by the preset power supply may include: an analog signal conditioning circuit AC power supply; an A/D sampling circuit power supply; a computer power supply; a PLC (Programmable Logic Controller, programmable logic controller) controller power supply; Controller control power supply and impulse voltage generator action power supply. Wherein, the structure of the preset power supply may be shown in FIG. 5 .

As an optional embodiment, the preset power supply is an uninterruptible power supply.

Among them, the analog signal conditioning circuit power supply, the A/D sampling circuit power supply, and the computer power supply share a common ground, and the ground potentials of the three power supplies are connected through magnetic beads. The power supply of the PLC controller and the ground potential of the control power supply of the impulse voltage generator are connected through magnetic beads. Accordingly, the remaining power supplies are isolated from each other. It should be noted that the above-mentioned controller 104 may be the above-mentioned PLC controller, which is not specifically limited in this embodiment of the present invention.

Specifically, the preset power supply may be a UPS (Uninterruptible Power System/Uninterruptible Power Supply, uninterruptible) power supply, which is not specifically limited in this embodiment of the present invention. For the UPS power supply, it can continuously supply 220V AC power to the load through the DC power through the inverter switching conversion mode, so that the load can maintain normal operation and can protect the software and hardware of the load from damage.

In order to facilitate the understanding of the control process of the impulse overvoltage, the synchronous triggering method of the power frequency freewheeling device provided by the embodiment of the present invention is now described. Wherein, the algorithm may be pre-configured on the computer side, which is not specifically limited in this embodiment of the present invention. Specifically, the input of the synchronous triggering algorithm is the power frequency voltage, the amplitude of the impulse voltage and the triggering phase angle. The amplitude and the current phase angle of the power frequency voltage are obtained through calculation, and when the current phase angle of the power frequency voltage reaches the trigger phase angle, an instruction is sent to the controller 104 to control the impulse voltage generator to trigger and generate the impulse overvoltage. The impulse voltage amplitude signal is input by the user to the computer-side processor, and the computer-side processor controls the capacitor charging time of the impulse voltage generator and the impact ball gap distance, and then controls the impulse voltage amplitude. Wherein, the control process of the synchronous triggering algorithm can refer to FIG. 6 .

As an optional embodiment, the primary side circuit includes a power frequency AC voltage source and an impulse voltage generator; the power frequency AC voltage source, the product under test and the impulse voltage generator are connected in parallel.

As an optional embodiment, the power frequency AC voltage source includes a voltage regulator and a test transformer; the voltage regulator is connected in parallel with the test transformer.

Specifically, as shown in FIG. 7 . The dotted box 1 in Fig. 7 represents the power frequency AC voltage source, which is input by the grid voltage AC and connected to the voltage regulator and the test transformer T. Among them, the test transformer outputs 50Hz power frequency voltage. The dotted box 2 represents the impulse voltage generator. When the gap breakdown is triggered, the charging capacitor discharges the load to generate an impulse voltage. The dotted box 3 represents the tested product, where S1 represents the series gap of the tested product, RT1 represents the zinc oxide resistance of the tested product; S2 represents the isolation ball gap between the impulse voltage source and the power frequency power supply; RT2 represents the transformer outlet protection surge arrester , L and R respectively represent the protection inductance and protection resistance, which are used to protect the test transformer from damage. V1 and V2 respectively represent the voltage on the test object and the output port voltage of the transformer, i represents the current flowing through the test object, V1, V2 and i belong to the measured, and are transmitted to the measurement circuit 102 as measurement signals.

The embodiment of the present invention can control the joint pressurization of the power frequency power supply and the impulse power supply, and measure the outlet voltage of the test transformer and the voltage and current applied to the test object, and then evaluate the ability of the arrester device to extinguish the power frequency arc under the action of lightning waves.

The primary side measurement circuit 101 provided by the embodiment of the present invention uses a voltage divider to measure the power frequency voltage and the voltage across the test object; uses a Rogowski coil to measure the current flowing through the test object. The voltage and current signals measured by the voltage divider and the Rogowski coil are photoelectrically isolated and transmitted to the signal conditioning and A/D conversion circuit, and the voltage and current are converted into digital quantities and then transmitted to the controller 104 . The control and measurement circuit provided by the embodiment of the present invention can effectively prevent the measured distortion caused by electromagnetic interference.

The control circuit 103 of the embodiment of the present invention calculates the trigger conduction time of the impulse voltage generator according to the measured power frequency voltage signal and the conduction phase angle input by the user, and triggers the conduction of the impulse voltage generator by the relay, so that the impulse and The power frequency voltage is superimposed in any phase to realize joint pressurization.

The power supply part of the present invention adopts UPS power supply to supply power alone, and the power supplies of the control circuit 103, the primary side measurement circuit 101 and the controller 104 are mutually isolated, which can effectively prevent the impulse overvoltage generated by the impulse voltage generator from affecting the control circuit 103 and the primary side measurement circuit 101 causing damage.

Finally, the method of the present application is only a preferred embodiment, and is not intended 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 within the protection scope of the present invention.

Claims (6)

1. The utility model provides a control measurement circuit of power frequency freewheel test device which characterized in that includes: the system comprises a primary side measuring circuit, a signal conditioning circuit, a control circuit and a controller;

the primary side measuring circuit is used for collecting measuring signals from the primary side circuit and transmitting the measuring signals to the signal conditioning circuit; the signal conditioning circuit is used for performing signal conditioning and digital-to-analog conversion on the measurement signals and transmitting the converted measurement signals to the controller; the controller is used for outputting a control signal to the control circuit according to the converted measurement signal, and the control circuit triggers a surge voltage generator in the primary side circuit to generate surge overvoltage; the control circuit, the signal conditioning circuit and the controller are powered by one path of voltage respectively, and all paths of voltages are mutually isolated;

the control measurement circuit further comprises a first photoelectric isolation module; the primary side measuring circuit is used for transmitting the measuring signal to the first photoelectric isolation module, and the first photoelectric isolation module is used for carrying out photoelectric isolation on the measuring signal and transmitting the measuring signal after photoelectric isolation to the signal conditioning circuit;

the control measurement circuit further comprises a second photoelectric isolation module; the control circuit is used for outputting a control signal to the second photoelectric isolation module according to the converted measurement signal; the second photoelectric isolation module is used for performing photoelectric isolation on the control signal and outputting the control signal subjected to photoelectric isolation to the control circuit.

2. The control measurement circuit of claim 1, wherein the measurement signal comprises a power frequency voltage signal, a voltage signal across the sample, and a current signal through the sample; the primary side measuring circuit comprises a resistor-capacitor voltage divider, a capacitor voltage divider and a rogowski coil, wherein the resistor-capacitor voltage divider is used for measuring the power frequency voltage signal, the capacitor voltage divider is used for measuring voltage signals at two ends of a tested article, and the rogowski coil is used for measuring current flowing through the tested article.

3. The control and measurement circuit of claim 1, wherein the control circuit, the signal conditioning circuit, and the controller are powered by a preset power source; the preset power supply is connected with an isolation transformer, multiple paths of voltages are output to the control circuit, the signal conditioning circuit and the controller through the isolation transformer, and the control circuit, the signal conditioning circuit and the controller correspond to one path of voltage respectively.

4. A control and measurement circuit according to claim 3, wherein the predetermined power source is an uninterruptible power source.

5. The control and measurement circuit of claim 2, wherein the primary side circuit comprises a power frequency ac voltage source and a surge voltage generator; the power frequency alternating current voltage source, the tested article and the impulse voltage generator are connected in parallel.

6. The control and measurement circuit of claim 5, wherein the power frequency ac voltage source comprises a voltage regulator and a test transformer; the voltage regulator is connected in parallel with the test transformer.

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