A bidirectional optocoupler 10kV line electrical testing device and its electrical parameter selection method

Abstract

The present invention discloses a bidirectional optocoupler type 10kV line test device and an electrical parameter selection method thereof. The test device includes an electromagnetic induction coil, a current limiting resistor, a bidirectional photocoupler, a relay, a power supply, an LED lamp, a buzzer, a first switch, an AC transformer, a rectifier circuit, a voltage regulator, an AD converter, a controller, an alarm circuit and a display circuit, which constitute a current measurement module, a high current test module and a low current test module. The bidirectional optocoupler type 10kV line test device disclosed by the present invention aims to improve the safety of the test process through non-physical contact; the electrical parameter selection method of the bidirectional optocoupler type 10kV line test device disclosed by the present invention aims to improve the accuracy of the test of the 10kV line.

Description

Technical Field

[0001] The invention relates to a bidirectional optical coupling type 10kV line electric testing device and an electric parameter selection method thereof, belonging to the field of electromagnetism and electronic technology. Background Art

[0002] With the rapid development of industrialization and urbanization in my country, the demand for electric energy in residents' production and life has also increased year by year. According to the latest statistics, my country's total electricity consumption in 2018 was 6844.9 billion kWh, an increase of 8.5% year-on-year; in the first half of 2019, my country's total electricity consumption was 3400 billion kWh, an increase of 5.0% year-on-year. The surge in electricity consumption will inevitably lead to the construction and development of power networks, especially 10kV lines, which have the characteristics of long mileage, many nodes, and criss-crossing. This brings a lot of workload and safety challenges to the operation and maintenance of our distribution network personnel.

[0003] When distribution network personnel are performing operation and maintenance work on 10kV lines, they first need to test the electricity of the 10kV lines. How to safely, accurately and conveniently perform electricity testing on 10kV lines has become the goal pursued by distribution network personnel and power scientists in recent years.

[0004] Chinese patent application CN201710440866.8 discloses a high-voltage live detection device based on an electric test electrode. The device is mainly composed of a high-voltage probe, an electric test electrode, a power supply, a power switch, a relay, an alarm light and a buzzer. The core working principle of the device is: when the high-voltage probe contacts the high-voltage line, due to the mutual repulsion of the same charges, the positive electrode blade and the negative electrode blade of the electric test electrode will be in a physically separated state, so that the normally closed contact of the relay is closed and the alarm circuit is driven to work; when the high-voltage probe does not contact the high-voltage line, the positive electrode blade and the negative electrode blade of the electric test electrode are in a physically contacted state, thereby prohibiting the alarm circuit from working through the power supply and the relay. The device does not have a key manual test function-it is impossible to test whether the electric test device is functioning properly. If the alarm circuit of the device is damaged, it is possible for the staff to misjudge, thereby increasing the unsafe factors of the staff in the power operation and maintenance process.

[0005] Chinese patent application CN201710440866.8 discloses an electrical testing device. The electrical testing device mainly includes a mounting seat, an insulating inner rod, an insulating outer rod, a limit block, a spring and an electrical testing device. The device focuses on the physical structure of the mounting seat, the insulating rod, the limit block and the electrical testing device from the perspective of mechanical structure, and has the advantages of simple structure, easy operation and disassembly. In view of the fact that the device also does not have a manual test mode to determine whether the electrical testing function is normal, this will inevitably increase the misjudgment and unsafe factors of the power testing staff. In addition, if the voltage (or current) of the live line or equipment is low, it may be impossible to effectively test the electricity, which will also increase the misjudgment and unsafe factors of the staff.

[0006] In summary, these electrical testing devices cannot accurately test live circuits, and do not have a self-test mode to check whether the functions are normal, and cannot accurately and safely test live circuits. Summary of the invention

[0007] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a bidirectional optical coupling type 10kV line electrical testing device and an electrical parameter selection method thereof. The electrical testing device utilizes electrical insulation characteristics and the principle of electromagnetic induction to measure whether the 10kV line is in a live operation state, and has high safety. On the basis of measuring that the 10kV line is energized, the electrical parameters of the electrical components are selected to automatically select an appropriate electrical testing module (a high current electrical testing module or a low current electrical testing module) for operation, thereby improving the electrical testing accuracy of the entire electrical testing device, and in particular, can improve the electrical testing accuracy of the 10kV line under low current electrical testing operation. At the same time, the electrical testing device adopts a bidirectional optical coupler and an AC transformer, which can realize non-physical contact form of electrical signal conversion or transmission, thereby further improving the safety of the entire electrical testing device.

[0008] Technical solution: To achieve the above purpose, the technical solution adopted by the present invention is:

[0009] A bidirectional optical coupling type 10kV line power testing device, comprising an electromagnetic induction coil, a current limiting resistor, a bidirectional photoelectric coupler, a relay, a power supply, an LED lamp, a buzzer, a first switch, an AC transformer, a rectifier circuit, a voltage regulator tube, an AD converter, a controller, an alarm circuit and a display circuit;

[0010] The electromagnetic induction coil, the current limiting resistor, the light emitting device of the bidirectional photoelectric coupler and the first switch are connected in series to form a loop, thereby forming a current measurement module;

[0011] The LED lamp and buzzer are connected in parallel and then connected in series with the light receiving device of the bidirectional photoelectric coupler, the relay coil of the relay and the power supply to form a loop, thereby forming a high current electric test module;

[0012] The light-emitting device of the bidirectional photoelectric coupler, the normally closed contact of the relay, the AC transformer, the rectifier circuit, the voltage regulator, the AD converter, the controller, the alarm circuit and the display circuit constitute a low-current electrical testing module; wherein the light-emitting device of the bidirectional photoelectric coupler, the normally closed contact of the relay and the primary side of the AC transformer are connected in series to form a loop, the secondary side voltage of the AC transformer is rectified, stabilized and AD converted by the rectifier circuit, the voltage regulator and the AD converter and then input into the controller, and the alarm circuit and the display circuit are both connected to the controller.

[0013] In this electrical testing device, the function of the current measurement module is to convert the alternating magnetic field energy around the 10kV line into the electrical energy of the electromagnetic induction coil (based on the principle of electromagnetic induction); the function of the relay is to automatically select the appropriate current electrical testing module (high current electrical testing module or low current electrical testing module) according to the current size of the 10kV line; the function of the high current electrical testing module is to realize the electrical testing of the 10kV line under high current operation; the function of the low current electrical testing module is to realize the electrical testing of the 10kV line under low current operation.

[0014] When the entire electrical testing device is performing electrical testing, it must be ensured that the electromagnetic induction coil and the 10kV line being measured are in the same plane, so that the alternating magnetic field lines around the 10kV line can pass through the electromagnetic induction coil as much as possible, thereby maximizing the conversion of the magnetic field energy around the 10kV line into electrical energy of the electromagnetic induction coil; at the same time, the closer the electromagnetic induction coil is to the 10kV line, the greater the induced electromotive force of the electromagnetic induction coil according to the principle of electromagnetic induction, which is conducive to enhancing the sensitivity of the measuring circuit.

[0015] Preferably, it also includes a functional self-test module, which includes a first functional self-test module and a second functional self-test module; the first functional self-test module includes a high-current power test module, a second switch and a 5V pulse power supply, the second switch and the 5V pulse power supply are connected in series and then connected in parallel with the first switch; the second functional self-test module includes a low-current power test module, a third switch and a 1V pulse power supply, the third switch and the 1V pulse power supply are connected in series and then connected in parallel with the first switch. The self-test module enables both the high-current and low-current power test modules to have a manual test function, which can test whether the high-current power test module and the low-current power test module can work normally, thereby preventing the occurrence of misjudgment of power test, and ultimately improving the safety of power test operators.

[0016] Preferably, the relay can realize the control of the high current power detection module and the low current power detection module so that the two will not run at the same time.

[0017] Preferably, the shape of the electromagnetic induction coil may be rectangular or circular; the outer surface of the electromagnetic induction coil is coated with insulating paint and covered with epoxy resin to ensure the insulation and firmness between each turn of the coil.

[0018] Preferably, the rectifier circuit is composed of two diodes and two capacitors, such as the existing common rectifier circuit; the voltage regulator tube is composed of a thyristor.

[0019] Preferably, the circuit structure of the 5V pulse power supply and the 1V pulse power supply is based on a 555 timer.

[0020] Preferably, it also includes a shell, the electromagnetic induction coil is fixed at one end of the shell, and the remaining components of the current measurement module, the high current test module, the low current test module and the non-controllable / monitoring components in the function self-test module are all installed in the shell; a telescopic rod is installed at the other end of the shell relative to the electromagnetic induction coil, and the shell and the telescopic rod are both made of electrically insulating materials. The function of the shell and the telescopic rod is to improve the anti-charge interference (shielding) ability of the entire test device, and to improve the safety and convenience of the test staff.

[0021] A method for selecting electrical parameters (specifications and models, such as voltage, current, etc.) of a bidirectional optical coupling type 10kV line electric test device. The electrical parameters of all circuit components are selected based on the operating characteristics of the 10kV line. This can ensure the accurate electric test work of the entire bidirectional optical coupling type 10kV line electric test device and improve the operating stability of the entire electric test device. The method mainly includes the following steps:

[0022] (a) monitor the 10 kV line current amplitude and proceed to step (b);

[0023] (b) Select the bidirectional photoelectric coupler model and the number of turns of the electromagnetic induction coil, and proceed to step (c);

[0024] (c) determining whether the number of turns of the electromagnetic induction coil meets the requirement: if not, returning to step (b); otherwise, selecting a current limiting resistor and proceeding to steps (d) and (e);

[0025] (d) Design a high-current electrical inspection module that is compatible with relay models, power supply voltage amplitudes, LED lights, and buzzer models;

[0026] (e) To design a low-current electrical detection module, first select the AC transformer model, then configure the diode and capacitor models, thyristor model, AD converter and controller model, alarm circuit and display circuit model in sequence.

[0027] Preferably, the number of turns N of the electromagnetic induction coil is determined by the current amplitude of the 10kV line. Specifically, the maximum operating current of the 10kV line in my country is about 380A. According to the full current law, the operating frequency of the 10kV line, the area of ​​the electromagnetic induction coil and the electromagnetic induced electromotive force formula The maximum induced electromotive force (voltage) of a single-turn electromagnetic induction coil is calculated. In the formula, Φ is the magnetic flux of the electromagnetic induction coil, and d is the differential symbol.

[0028] Preferably, based on the known number of turns N of the electromagnetic induction coil and the electromagnetic induced electromotive force E, a bidirectional photocoupler of appropriate model and specification can be selected to make the light-emitting device of the bidirectional photocoupler conduct when the 10kV line is running at a higher current, thereby driving the high-current power detection module to operate; and to make the light-emitting device of the bidirectional photocoupler cut off when the 10kV line is running at a low current, thereby driving the low-current power detection module to operate. Preferably, the model of the bidirectional photocoupler HCPL-814-000E is selected, and its conduction voltage is 1.4V.

[0029] Preferably, the function of the current-limiting resistor is to make the induced current of the electromagnetic induction coil smaller than the maximum operating current of the bidirectional photoelectric coupler, thereby ensuring that the bidirectional photoelectric coupler is not broken down by a large current.

[0030] Preferably, the pulse power amplitude of the high and low current test modules should be selected according to the model and specification of the bidirectional photoelectric coupler.

[0031] Preferably, the specification and model of the relay should be consistent with the power supply specification and model of the high current power detection module, so that the relay can automatically select only one current power detection module to operate at any time.

[0032] Preferably, the specifications and models of the AC transformer, diode, capacitor and voltage regulator should be selected to maintain voltage amplitude compatibility with the subsequent AD converter.

[0033] Preferably, in order to further improve the accuracy of the electrical detection of the 10 kV line under low current operation, a higher resolution AD converter and a higher digit display circuit may be used.

[0034] Preferably, in order to improve the signal processing speed of the low-current electrical detection module, a controller chip with faster computing power and calculation accuracy can be selected.

[0035] Beneficial effects: The bidirectional optical coupling type 10kV line electrical testing device and the electrical parameter selection method provided by the present invention have the following advantages over the prior art: 1. The present invention utilizes the electrical insulation method and the electromagnetic induction principle to convert the magnetic field energy around the 10kV line into the electrical energy of the electromagnetic induction coil, which preliminarily improves the safety of the entire device; 2. The present invention realizes the non-physical conversion or transmission of electrical signals through a bidirectional optical coupler and an AC transformer, further improving the safety of the entire device; 3. The present invention uses a relay coil and a relay normally closed contact to identify the operating state of the 10kV line (high current state or low current state), thereby automatically selecting the appropriate current electrical testing module to operate, and ultimately improving the electrical testing accuracy of the entire device; 4. The electrical parameter selection method of the device and components of the present invention can also be applied to the electrical testing work of high-voltage lines such as 35kV and 110kV. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The working process of the electromagnetic induction coil converting the magnetic field energy around the 10kV line into electrical energy;

[0037] Figure 2 It is a system assembly of a bidirectional optically coupled 10kV line power testing device;

[0038] Figure 3 This is a circuit diagram of a bidirectional optocoupler 10kV line power test device;

[0039] Figure 4 This is a basic circuit diagram of a 5V pulse power supply and a 1V pulse power supply;

[0040] Figure 5 This is a flow chart of the method for selecting electrical parameters of components of a bidirectional optocoupler 10kV line electrical testing device. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the accompanying drawings.

[0042] like Figure 1 As shown in the figure, it is the working process of the electromagnetic induction coil converting the magnetic field energy around the 10kV line into electrical energy; the figure includes a certain phase 10kV line 1, current 2, magnetic field 3, electromagnetic induction coil 4 and current limiting resistor 5, and the current 2 flows from right to left. Since the 10kV line in my country is an AC transmission line, according to the law of full current, the alternating current 2 must generate an alternating magnetic field 3 around the 10kV line 1. In this case, if the electromagnetic induction coil 4 is near the 10kV line 1, according to the law of electromagnetic induction, the electromagnetic induction coil 4 will generate an alternating electromotive force (voltage) in the alternating magnetic field 3, and form a loop through the current limiting resistor 5. This is the working process of converting the magnetic field energy around the 10kV line into the electromagnetic induction coil electrical energy.

[0043] According to the electromagnetic induction theory, only when the electromagnetic induction coil 4 and the 10kV line 1 are in the same plane can the magnetic field energy around the 10kV line 1 be converted into electrical energy to the maximum extent; and the closer the electromagnetic induction coil 4 is to the 10kV line 1, the greater the rate of change of the magnetic flux per unit time, and the greater the induced electromotive force (voltage) of the electromagnetic induction coil 4.

[0044] The main function of the current limiting resistor 5 is to limit the current amplitude of the electromagnetic induction coil loop according to the working characteristics of the 10kV line 1, which is helpful to prevent the bidirectional photoelectric coupler 8 from being damaged due to overcurrent.

[0045] like Figure 2 As shown, the system assembly of a bidirectional optical coupling 10kV line power testing device includes a current measurement module, a relay 9, a high current power testing module, a low current power testing module, a functional self-test module, a housing 6 and a telescopic rod 7.

[0046] like Figure 3 The figure shows a circuit structure diagram of a bidirectional optocoupler 10kV line electrical testing device. Figure 3 It is mainly composed of four circuit structures, namely the current measurement module of the bidirectional optocoupler 10kV line, the high current test module, the low current test module and the function self-test module. Among them, the current measurement module is composed of the electromagnetic induction coil 4, the current limiting resistor 5, the switch position ① of the three-position switch 13 and the light-emitting device 81 of the bidirectional photoelectric coupler 8; the high current test module is composed of the light receiving device 82 of the bidirectional photoelectric coupler 8, the relay coil 91, the power supply 10, the LED lamp 11 and the buzzer 12; the low current test module is composed of the light-emitting device 81 of the bidirectional photoelectric coupler 8, the relay normally closed contact 92, the AC transformer 16, the diode 17, the capacitor 18, the thyristor 19, the AD converter The functional self-test module refers to the functional self-test of the high-current power test module and the self-test of the low-current power test module. The functional self-test of the high-current power test module is composed of a 5V pulse power supply 14, a switch position ② of the three-position switch 13, a current limiting resistor 5, an electromagnetic induction coil 4 and a high-current power test circuit. The functional self-test of the low-current power test module is composed of a 1V pulse power supply 15, a switch position ③ of the three-position switch 13, a current limiting resistor 5, an electromagnetic induction coil 4 and a low-current power test circuit.

[0047] Because the three-position switch 13 is adopted, Figure 2 and Figure 3 Of the measurement circuits shown, the high current self-test module (functional self-test 1) and the low current self-test module (functional self-test 2), only one circuit is in operation at any given moment.

[0048] The working process of the current measurement module is as follows: after the switch position ① of the three-position switch 13 is closed, when the electromagnetic induction coil 4 generates an alternating voltage in the magnetic field around the 10kV line 1 (such as Figure 1 As shown), the circuit consisting of the switch position ① of the three-position switch 13, the current limiting resistor 5, the electromagnetic induction coil 4 and the light-emitting device 81 of the bidirectional photoelectric coupler 8 is turned on. If the voltage amplitude of the electromagnetic induction coil 4 is greater than or equal to the turn-on voltage of the light-emitting device 81 of the bidirectional photoelectric coupler 8, the light-emitting device 81 of the bidirectional photoelectric coupler 8 is turned on; if the voltage amplitude of the electromagnetic induction coil 4 is less than the turn-on voltage of the light-emitting device 81 of the bidirectional photoelectric coupler 8, the light-emitting device 81 of the bidirectional photoelectric coupler 8 is not turned on.

[0049] Specifically, the relay 9 can drive the high current test module or the low current test module to operate according to whether the light emitting device 81 of the bidirectional photoelectric coupler 8 is turned on. The specific control process is: when the induced voltage amplitude of the electromagnetic induction coil 4 is large (greater than or equal to the conduction value of the light emitting device 81), the light emitting device 81 of the bidirectional photoelectric coupler 8 is turned on, and the light receiving device 82 of the bidirectional photoelectric coupler 8, the relay coil 91, the power supply 10, the LED lamp 11 and the buzzer 12 form a current loop, and at the same time, the normally closed contact 92 of the relay is disconnected (according to the working principle of the relay), and only the high current test module operates at this time; when the induced voltage amplitude of the electromagnetic induction coil 4 is small (less than the conduction value of the light emitting device 81), the light emitting device 81 of the bidirectional photoelectric coupler 8 is cut off, and at this time the light receiving device 82 of the bidirectional photoelectric coupler 8 is in the disconnected state, and the relay coil 91 loses power (the normally closed contact 92 of the relay is in the closed state), then the voltage values ​​on both sides of the light emitting device 81 of the bidirectional photoelectric coupler 8 are converted by the AC transformer 16, and the low current test module is driven to operate.

[0050] According to the current characteristics of my country's 10kV line (maximum current 380A), and in the case of selecting an appropriate number of turns of the electromagnetic induction coil (see below for details Figure 4 As described in the accompanying drawings), the model of the bidirectional photoelectric coupler 8 used in the present invention is HCPL-814-000E, and its electrical parameters are: the on-state voltage of the light emitting device 81 of the bidirectional photoelectric coupler 8 is 1.4V.

[0051] The working process of the high current electrical detection module is: the current 2 of the 10kV line 1 is a high current → the induced voltage amplitude of the electromagnetic induction coil 4 is greater than 1.4V → the light emitting device 81 of the bidirectional photoelectric coupler 8 is turned on → the light receiving device 82 of the bidirectional photoelectric coupler 8 is turned on → the light receiving device 82 of the bidirectional photoelectric coupler 8, the relay coil 91, the power supply 10, the LED lamp 11 and the buzzer 12 form a circuit → the LED lamp 11 and the buzzer 12 alarm.

[0052] Since the 10kV line 1 is an AC transmission line, the induced voltage in the electromagnetic induction coil 4 is also alternating, which will cause the light emitting device 81 and the light receiving device 82 of the bidirectional photoelectric coupler 8 to be intermittently turned on or off, thereby causing the LED lamp 11 of the high current test circuit to be in a flashing state, and the buzzer 12 to be in an intermittent beeping state. However, in fact, the operating frequency of the 10kV line 1 in my country is 50Hz, so the above-mentioned flashing of the LED lamp 11 and the intermittent beeping state of the buzzer 12 cannot be captured by human vision and hearing. It can be considered that the LED lamp 11 is in a constant light state, and the buzzer 12 is in a continuous beeping state.

[0053] When the high current test module is running, since the relay coil 91 is energized, the normally closed contact 92 of the relay is disconnected, thereby prohibiting the low current test module from running, thus ensuring the accuracy of the entire 10kV test circuit (indicating that the 10kV line is in a high current operating state).

[0054] The working process of the low-current electrical detection module is: the current 2 of the 10kV line 1 is a low current → the induced voltage amplitude of the electromagnetic induction coil 4 is less than 1.4V → the light-emitting device 81 and the light-receiving device 82 of the bidirectional photoelectric coupler 8 are both in the cut-off state → the normally closed contact 92 of the relay is in the closed state → the AC transformer 16 works and converts the low voltage on both sides of the bidirectional photoelectric coupler 8 into a high voltage → the full-wave rectifier circuit works (composed of a diode 17 and a capacitor 18) → the AD converter converts the full-wave rectified DC voltage into a digital signal → the controller performs program analysis and calculation based on the digital signal provided by the AD converter and the transformation ratio parameters of the AC transformer 16 → drives the alarm circuit to work and displays the current current 2 amplitude of the 10kV line 1.

[0055] In the low-current electrical test module, the function of the component Zener diode 19 is: when the voltage output by the full-wave rectification is greater than the maximum withstand voltage of the AD converter, the Zener diode 19 will be broken down and turned on by the voltage output by the full-wave rectification, which will provide overvoltage protection for the circuit after the Zener diode 19.

[0056] Since the induced voltage amplitude of the electromagnetic induction coil 4 is less than 1.4V, the light emitting device 81 of the bidirectional photoelectric coupler 8 is cut off and turned on, and the light receiving device 82 of the bidirectional photoelectric coupler 8 is cut off and turned on, which will prohibit the operation of the high current test module, thereby ensuring the measurement accuracy of the entire 10kV test circuit (indicating that the 10kV line is operating in a low current state).

[0057] Specifically, in order to improve the conversion accuracy of the AD converter, a higher resolution AD converter may be used, such as a 14-bit or 16-bit AD converter.

[0058] Specifically, the controller can be formed by using AT series single-chip microcomputer chips. If the operation speed and accuracy of the controller are to be improved, a TI series digital signal processing chip can also be used.

[0059] Specifically, the alarm circuit of the low current test module may be composed of an LED lamp and a buzzer; the display circuit of the low current measurement module may use a seven-segment code device or a liquid crystal display device.

[0060] The working process of the functional self-test module is: when the 10kV line power test is not performed, the switch position ② of the three-position switch 13 is closed, and the 5V pulse power supply 14 supplies power to the bidirectional photoelectric coupler 8 through the electromagnetic induction coil 4 and the current limiting resistor 5, so that the light-emitting device 81 of the bidirectional photoelectric coupler 8 is turned on, thereby enabling the high-current power test module to operate; when the 10kV line power test is not performed, the switch position ③ of the three-position switch 13 is closed, and the 1V pulse power supply 15 supplies power to the bidirectional photoelectric coupler 8 through the electromagnetic induction coil 4 and the current limiting resistor 5, but because the voltage amplitude of the 1V pulse power supply 15 is small, the light-emitting device 81 and the light receiving device 82 of the bidirectional photoelectric coupler 8 are in the cut-off state, and the relay coil 91 loses power (the relay normally closed contact 92 is closed), so the AC transformer 16 is in a working state, thereby driving the low-current power test module to operate.

[0061] as follows Figure 4 As shown in the figure, it is a basic circuit structure diagram of 5V pulse power supply and 1V pulse power supply, which is actually a multivibrator circuit built based on 555 timer. In the figure, pins 1, 2, 3, 4, 5, 6, 7 and 8 are the eight pins of 555 timer, and R1, R2, C1 and C2 are the external resistors and capacitors of 555 timer. According to the operating principle of the multivibrator composed of 555 timer, when appropriate resistors R1, R2, C1 and C2 are selected, pin 3 of 555 timer can output pulse voltage, and the amplitude of the pulse voltage is equal to the external DC power supply voltage V of 555 timer. CC .

[0062] In particular, the duty cycle and period of the pulse voltage output from pin 3 of the 555 timer are 0.7×(R1+R2)×C1 and 0.7×(R1+2R2)×C1, respectively. Therefore, different DC power supply voltage amplitudes V CC (For example, 5V or 1V), the circuit can generate 5V pulse power supply and 1V pulse power supply.

[0063] In particular, the period of the 5V pulse power supply and the 1V pulse power supply should be close to 0.02 seconds (50Hz) in order to keep consistent with the voltage frequency of my country's power grid.

[0064] as follows Figure 5The figure shows a flow chart of the method for selecting the electrical parameters of components of a bidirectional optical coupling type 10kV line tester. The electrical parameters of components involved in the present invention are mainly electrical parameters such as voltage, current, resistance and number of turns of electromagnetic coil, which will determine the stability and accuracy of the entire bidirectional optical coupling type 10kV line tester.

[0065] Furthermore, the maximum current of my country's 10kV line is about 380A, and the rated current is about 200A. This electrical parameter will determine the selection of the model of the bidirectional photocoupler 8 and the number of turns of the electromagnetic induction coil 4. For example: First, the model of the bidirectional photocoupler 8 is HCPL-814-000E, whose on-state voltage is 1.4V and the maximum withstand voltage is 5V; secondly, assuming that the area of ​​the electromagnetic induction coil 4 is 0.06m 2 , the number of turns N = 1000, the current of the 10kV line is the maximum value (380A), and the electromagnetic induction coil 4 is close to the 10kV line. The induced electromotive force of the electromagnetic induction coil 4 can be calculated according to the full current law, the operating frequency of the 10kV line and the law of electromagnetic induction: Where Φ is the magnetic flux of the electromagnetic induction coil 4. In this example, it can be obtained from the on-voltage (1.4V) of the bidirectional photocoupler 8 and the induced electromotive force (4.8V) of the electromagnetic induction coil 4 that the light emitting device 81 of the bidirectional photocoupler 8 is turned on, so that the high current test module of the bidirectional photocoupler 10kV line test device is in operation.

[0066] When the current amplitude of the 10kV line is less than 120A, the induced electromotive force of the electromagnetic induction coil 4 is less than 1.4V, and the light emitting device 81 of the bidirectional photoelectric coupler 8 is cut off, so that the low current test module of the bidirectional photocoupler 10kV line test device is in operation.

[0067] Specifically, the wire diameter of the electromagnetic induction coil 4 can be selected to be smaller, for example, the wire diameter of the electromagnetic induction coil 4 is 0.1 mm. In this case, the electromagnetic induction coil 4 can be prevented from being burned by overvoltage and the cost investment can be reduced.

[0068] In order to prevent a large loop current from burning out the light emitting device 81 of the bidirectional photoelectric coupler 8, a current limiting resistor 5 with an appropriate resistance value may be used to reduce the current value of the entire measurement loop.

[0069] Specifically, the models of the relay 9, the power supply 10, the LED lamp 11 and the buzzer 12 need to be compatible and matched. For example, when the high-current power test module is running, it is necessary to ensure that the voltage of the power supply 10 can drive the LED lamp 11 and the buzzer 12 to work normally, and to ensure that the voltage of the power supply 10 can drive the normally closed contact 92 of the relay to open. This is the key factor for the high-current power test module and the low-current power test module to achieve non-simultaneous operation.

[0070] When the low-current power test module is running, the transformation ratio of the AC transformer 16 is generally less than 5, which is conducive to the subsequent full-wave rectifier current construction, AD converter and controller selection. For example, when the low-current power test module is running, the light-emitting device 81 of the bidirectional photocoupler 8 is turned off and turned on, and the voltage on both sides is less than 1.4V. After passing through a small AC transformer with a transformation ratio of 5 and a full-wave rectifier circuit, the maximum voltage amplitude of the capacitor 18 is E1=1.4×5×1.414=9.89V. In this case, according to the maximum voltage of the capacitor 18 (9.89V), an AD converter of appropriate model and specification can be selected, and the analog signal can be converted into a digital signal for subsequent controller data analysis and processing.

[0071] Specifically, the type of the voltage regulator tube 19 is also selected based on the maximum open circuit voltage (9.89V) of the capacitor 18. The function of the voltage regulator tube 19 is to provide overvoltage protection for the subsequent circuit.

[0072] Specifically, the alarm circuit of the low current electricity testing module can also be composed of an LED light and a buzzer.

[0073] Specifically, in order to further improve the accuracy of the electrical detection of the 10 kV line under low current operation, a higher resolution AD converter and a higher digit display circuit can be used.

[0074] Specifically, in order to improve the signal processing speed of the low-current electrical detection module, a controller chip with faster computing power and calculation accuracy can be selected, such as a DSP control chip of the TI series.

[0075] The electrical parameters of the components of functional self-test 1 and functional self-test 2 are also based on the above-mentioned component electrical parameter selection method. The principle of electrical parameter selection is: it can not only prevent the components of the entire 10kV line electrical test device from being damaged due to electrical reasons such as overvoltage and overcurrent, but also ensure that the functional self-test of the high and low current electrical test modules can be carried out successfully.

[0076] The above is a comprehensive description of the bidirectional optical coupling type 10kV line test device and the electrical parameter setting method of the present invention. It should be noted that: without adopting new technologies, new methods or new theories, it is only necessary to adjust the component parameters and structural dimensions of the structure shown in the drawings of the present invention to obtain a test device for 35kV, 110kV, and 220kV lines.

[0077] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for selecting electrical parameters of a bidirectional optically coupled 10kV line electrical testing device, characterized in that: It comprises an electromagnetic induction coil (4), a current limiting resistor (5), a bidirectional photoelectric coupler (8), a relay (9), a power supply (10), an LED lamp (11), a buzzer (12), a first switch, an AC transformer (16), a rectifier circuit, a voltage regulator tube, an AD converter, a controller, an alarm circuit, a function self-test module and a display circuit; The electromagnetic induction coil (4), the current limiting resistor (5), the light emitting device (81) of the bidirectional photoelectric coupler (8), and the first switch are connected in series to form a loop, thereby constituting a current measurement module; The LED lamp (11) and the buzzer (12) are connected in parallel and then connected in series with the light receiving device (82) of the bidirectional photoelectric coupler (8), the relay coil (91) of the relay (9) and the power supply (10) to form a loop, thereby forming a high-current electrical testing module; The light emitting device (81) of the bidirectional photoelectric coupler (8), the normally closed contact (92) of the relay (9), the AC transformer (16), the rectifier circuit, the voltage regulator tube, the AD converter, the controller, the alarm circuit and the display circuit constitute a low current electric detection module; wherein the light emitting device (81) of the bidirectional photoelectric coupler (8), the normally closed contact (92) of the relay (9) and the primary side of the AC transformer (16) are connected in series to form a loop, the secondary side voltage of the AC transformer (16) is rectified, stabilized and AD converted by the rectifier circuit, the voltage regulator tube and the AD converter and then input into the controller, and the alarm circuit and the display circuit are both connected to the controller; The functional self-test module comprises a first functional self-test module and a second functional self-test module; the first functional self-test module comprises a high current power test module, a second switch and a 5V pulse power supply (14), the second switch and the 5V pulse power supply (14) are connected in series and then connected in parallel with the first switch; the second functional self-test module comprises a low current power test module, a third switch and a 1V pulse power supply (15), the third switch and the 1V pulse power supply (15) are connected in series and then connected in parallel with the first switch; The electrical parameters of all circuit components are selected based on the operating characteristics of the 10kV line, including the following steps: ( a ) monitor the 10kV line current amplitude and proceed to step ( b ); ( b ) Select the bidirectional optocoupler model and the number of turns of the electromagnetic induction coil, and enter step ( c ); ( c ) Determine whether the number of turns of the electromagnetic induction coil meets the requirements: If not, return to step ( b ); Otherwise, select the current limiting resistor and proceed to step ( d ) and steps ( e ); ( d ) Design high current electric test module, compatible with relay model, power supply voltage amplitude, LED light and buzzer model; ( e ) To design a low-current electrical detection module, first select the AC transformer model, and then configure the diode and capacitor models, thyristor models, AD converter and controller models, alarm circuit and display circuit models in sequence.

2. The electrical parameter selection method of the bidirectional optical coupling type 10kV line electrical testing device according to claim 1 is characterized in that: The outer surface of the electromagnetic induction coil (4) is coated with insulating paint and covered with epoxy resin.

3. The electrical parameter selection method of the bidirectional optical coupling type 10kV line electrical testing device according to claim 1 is characterized in that: The rectifier circuit is composed of two diodes (17) and two capacitors (18), and the voltage regulator is composed of a thyristor (19).

4. The electrical parameter selection method of the bidirectional optical coupling type 10kV line electrical testing device according to claim 1 is characterized in that: It also includes a shell (6), the electromagnetic induction coil (4) is fixed at one end outside the shell (6), and the remaining components of the current measurement module, the high current test module, the low current test module and the non-controllable / monitoring components in the function self-test module are all installed in the shell (6); a telescopic rod (7) is installed at the other end of the shell (6) outside the electromagnetic induction coil (4), and the shell (6) and the telescopic rod (7) are both made of electrically insulating materials.

5. The electrical parameter selection method of the bidirectional optical coupling type 10kV line electrical testing device according to claim 1 is characterized in that: The bidirectional optocoupler model HCPL-814-000E is selected, and the on-state voltage is 1.4V.

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