CN2938123Y - Power Grid Insulation Resistance Detection Device - Google Patents

Abstract

Disclosed is a power grid insulation impedance detection device, comprising a DSP application system which controls the whole machine, a zero sequence current input circuit whose output terminal is connected to the DSP application system, a zero sequence voltage input circuit whose output terminal is connected to the DSP application system, a keyboard input circuit output terminal is connected to the DSP application system, a serial communication circuit which is linked with the DSP application system, a display circuit whose input terminal is connected to the DSP application system. The utility model detects the insulation parameters of the ground resistance during the extra single phase. Compared with the current power grid impedance resistance and impedance detection device, the utility model has the advantages of reasonable design, simple structure, good security, wide practice and accurate detection result. The utility model provides a reliable basis for the application of the power grid safety technology such as creepage protection, grounding protection and power grid tuning technology; the utility model can be popularized and applied in up or down the pit power grid detection.

Description

Power Grid Insulation Resistance Detection Device

technical field

The utility model belongs to the technical field of devices for measuring resistance, reactance, impedance or other derived characteristics, and in particular relates to the real value of resistance, reactance, or other derived characteristics of other two ends measured by another power supply current element or network impedance measurement or complex-valued measurements.

Background technique

The insulation resistance to ground and the distributed capacitance to ground are two parts of the insulation resistance of the power grid, and are important parameters related to the safe operation of the power grid. The insulation resistance of the power grid determines the active leakage current and capacitive current of the power grid to a large extent. It is the main factor affecting the electric shock current of the power grid and the magnitude of the single-phase grounding current. In the resonant grounding system with arc suppression coil, the accurate measurement of capacitive current is the core issue of reasonable adjustment of arc suppression coil. When the power grid is running, insulation resistance and capacitance to ground are constantly changing due to external factors, so they must be measured frequently.

In literature and practice, the measurement methods of capacitive current are mostly mentioned, such as single-phase direct metallic grounding method, neutral point applied voltage method, neutral point applied capacitance method, relative ground additional capacitance method, tuning method, non-conductive Balance voltage real-time measurement method, injection signal method. In fact, the capacitive current is the effect form of the ground capacitance when the power grid is running, and the ground capacitance can be further calculated through the measured capacitive current. It can be seen that various methods of measuring capacitance current are essentially methods of measuring capacitance to ground.

Among the various measurement methods, except for the single-phase direct metallic grounding method, other measurement methods ignore the influence of the insulation resistance to the ground, and approximate the capacitive current or the capacitance to the ground with the full current or full insulation resistance of the system. In other words, the insulation resistance and the capacitance to ground cannot be distinguished, which is acceptable when the influence of the insulation resistance is minimal, but the insulation resistance of the actual system cannot be completely ignored, thus causing errors in the measurement of insulation parameters. In addition, in the calculation process of existing measurement methods, additional components are involved in the calculation, and the error between the nominal value and actual value of the external components directly affects the accuracy of the obtained grid insulation parameters. The widely used method of adding capacitance, when adding a capacitor, due to the charging and discharging effect of the capacitor, at the moment of artificial grounding, it is equivalent to a metallic grounding fault in the power grid, which is obviously not conducive to safety; The method discharges the capacitor energy storage in time. The single-phase direct metallic grounding method is more intuitive. It can measure the insulation resistance and ground capacitance of the power grid, and can distinguish the active component and reactive component of the residual current, but the metallic grounding has certain dangers. In addition, various existing measurement methods are respectively applicable to a specific neutral point operating system, and their versatility is poor.

A technical problem urgently needed to be solved by current production units and power systems is to provide a measuring device for the insulation resistance and capacitance of the power grid to ground.

Contents of the invention

The technical problem to be solved by the utility model is to overcome the shortcomings of the above-mentioned measuring device for the insulation resistance to the ground and the capacitance to the ground of the power grid, and to provide a device with reasonable design, simple structure, good safety, accurate measured data, and suitable for different neutral points. The grounding system, the resonant grounding system, and the grid insulation impedance detection device that can distinguish between the ground insulation resistance and the ground capacitance at the same time when the neutral point is grounded by resistance.

The technical solution adopted to solve the above-mentioned technical problems is that it includes: a DSP application system controlling the whole machine; a zero-sequence current input circuit, the output terminal of which is connected to the DSP application system; a zero-sequence voltage input circuit, the output terminal of which is connected to the DSP application system; a keyboard input circuit, the output terminal of which is connected to the DSP application system; a serial communication circuit, which is connected to the DSP application system; it also includes a display circuit, the input terminal of which is connected to the DSP application system.

The zero-sequence current input circuit of the utility model is: the input zero-sequence current signal is input from the inverting input terminal of the integrated circuit U2B through R12 and R11, the non-inverting input terminal of the integrated circuit U2B is grounded through R9, and the inverting input terminal is connected through R10. The positive pole of the 2.5V power supply is connected to the output terminal through R8, the output terminal is connected to the inverting input terminal of the integrated circuit U2A through R7 and the inverting input terminal is connected through R8, one end of R13 is connected to one end of R12, and the other end is grounded, and one end of C6 is connected to R12 The other end and the other end of the integrated circuit U2A are grounded, the non-inverting input end of the integrated circuit U2A is grounded through R6, the inverting input end is connected to the output end through R5, the output end is connected to the DSP application system through R4, the 4-pin is connected to the positive pole of the 3.3V power supply, and the 11-pin is connected to the 3.3V power supply. V power supply negative.

The zero-sequence voltage input circuit of the utility model is: the input zero-sequence voltage signal is input from the inverting input terminal of the integrated circuit U2D through R22 and R21, the non-inverting input terminal of the integrated circuit U2D is grounded through R19, and the inverting input terminal is connected through R20. The positive pole of the 2.5V power supply is connected to the output end through R18, the output end is connected to the inverting input end of the integrated circuit U2C through R17, one end of C7 is connected between R21 and R22, and the other end is grounded, and the non-inverting input end of the integrated circuit U2C is grounded through R16. The inverting input terminal is connected to the output terminal through R15, and the output terminal is connected to the DSP application system through R14.

The model of integrated circuit U2A and integrated circuit U2B of the utility model is MCP604.

The model of integrated circuit U2C and integrated circuit U2D of the utility model is MCP604.

The utility model adopts an additional single-phase-to-ground resistance to measure insulation parameters. Compared with the existing grid impedance measuring resistor and reactance device, the utility model has the advantages of reasonable design, simple structure, good safety, wide practicability, and accurate measured data. It provides a reliable basis for the implementation of power grid safety technologies such as leakage protection, grounding protection, and power grid tuning. It can be popularized and used in the detection of the above-ground power grid or the down-hole power grid.

Description of drawings

Fig. 1 is the electrical principle block diagram of the present utility model.

Fig. 2 is the schematic diagram of the electronic circuit of the present utility model.

Detailed ways

The utility model is described in further detail below in conjunction with accompanying drawing and embodiment, but the utility model is not limited to these embodiments.

Fig. 1 is the electrical principle block diagram of the present utility model, see Fig. 1. In Fig. 1, the utility model is composed of a zero-sequence current input circuit, a zero-sequence voltage input circuit, a DSP application system, a serial communication circuit, a keyboard input circuit, and a display circuit. The zero-sequence current input circuit, the zero-sequence voltage input circuit and the output terminal of the keyboard input circuit are connected to the DSP application system, the DSP application system is connected to the serial communication circuit, and the output terminal of the DSP application system is connected to the display circuit.

In Fig. 2, the zero-sequence current input circuit of this embodiment is composed of integrated circuit U2A, integrated circuit U2B, R4-R13, and C6 connected. The model of integrated circuit U2A and integrated circuit U2B is MCP604. The input zero-current signal is input from the inverting input terminal of the integrated circuit U2B through R12 and R11, the non-inverting input terminal of the integrated circuit U2B is grounded through R9, the inverting input terminal is connected to the positive pole of the 2.5V power supply through R10, and the output terminal is connected to the output terminal through R8. The terminal is connected to the inverting input terminal of the integrated circuit U2A through R7, one end of R13 is connected to one end of R12, and the other end is grounded, one end of C6 is connected to the other end of R12, and the other end is grounded, and R13 and C6 form a filter for zero sequence current input signals . The noninverting input terminal of integrated circuit U2A is grounded through R6, the inverting input terminal is connected to the output terminal through R5, the output terminal is connected to the DSP application system through R4, pin 4 is connected to the positive pole of the 3.3V power supply, and pin 11 is connected to the negative pole of the 3.3V power supply.

The zero-sequence voltage input circuit of this embodiment is composed of integrated circuit U2C, integrated circuit U2D, R14-R22, and C7 connected. The model of integrated circuit U2C and integrated circuit U2D is MCP604. The input zero-sequence voltage signal is input from the inverting input terminal of the integrated circuit U2D through R22 and R21, the non-inverting input terminal of the integrated circuit U2D is grounded through R19, the inverting input terminal is connected to the positive pole of the 2.5V power supply through R20, and the output terminal is connected through R18. The output end is connected to the inverting input end of the integrated circuit U2C through R17, one end of C7 is connected between R21 and R22, and the other end is grounded. The noninverting input terminal of the integrated circuit U2C is grounded through R16, the inverting input terminal is connected to the output terminal through R15, and the output terminal is connected to the DSP application system through R14.

The keyboard input circuit of this embodiment is formed by connecting keys S2 to S17. One end of button S2, button S6, button S10, and button S14 is connected to the positive pole of 3.3V power supply through R26, one end of button S3, button S7, button S11, and button S15 is connected to the DSP application system and connected to the positive pole of 3.3V power supply through R27, and button S4, One end of button S8, button S12, and button S16 is connected to the DSP application system and connected to the positive pole of 3.3V power supply through R28. One end of button S5, button S9, button S13, and button S17 is connected to the DSP application system and connected to the positive pole of 3.3V power supply through R29. The other end of S2～button S17 is connected with DSP application system.

The DSP application system of this embodiment is composed of integrated circuits U1, R1-R3, C1-C5, key S1, and oscillator CRY1 connected together. The model of the integrated circuit U1 is LF2407A. Pin 107 of the integrated circuit U1 is connected to the output end of the integrated circuit U2A through R4, pin 109 is connected to the output end of the integrated circuit U2C through R14, pin 19 is connected to the other end of the button S2 ~ button S5, and pin 119 is connected to the other end of the button S6 ~ button S9 One end, pin 30 is connected to the other end of button S10 ~ button S13, pin 32 is connected to the other end of button S14 ~ button S17, pin 33 is connected to the positive pole of 3.3V power supply through R26, pin 35 is connected to the positive pole of 3.3V power supply through R27, pin 72 is connected to the positive pole of the 3.3V power supply through R27 Connect to the positive pole of 3.3V power supply, connect pin 70 to the positive pole of 3.3V power supply through R29, pin 123 and pin 124 to the oscillation circuit connected by C4 and C5 and oscillator CRY1, pin 10 to one end of R3 and C3, and pin 11 to one end of C2 and the other end of C3, the other end of R3 is connected to the other end of C2, the 133 pin is connected to one end of R1 and C1 and connected to the positive pole of 3.3V power supply through R2, one end of button S1 is connected to the other end of R1, the other end is grounded, and the other end of C1 One end is grounded. The power supply terminal of the integrated circuit U1 is connected to the positive pole of the 3.3V power supply, and the ground terminal is grounded. The 25 pins and 26 pins of the integrated circuit U1 are connected to the serial communication circuit, and the 81 pin outputs the switching signal of the resistor. The 40 pins, 44 pins, 47 feet, 52 feet, 73 feet, 65 feet, 62 feet, 59 feet, 55 feet, 46 feet, 38 feet, 88 feet are connected to the display circuit.

The serial communication circuit of this embodiment is composed of an integrated circuit U3, diodes D1, R23-R25, C8-C11, and socket RS-1 connected. The model of the integrated circuit U3 is MAX232CPE. Pin 9 of integrated circuit U3 is connected to pin 26 of integrated circuit U1 through R25 and grounded through R23, pin 10 is connected to the positive pole of diode D1 and positive pole of 5V power supply through R24, the negative pole of diode D1 is connected to pin 25 of integrated circuit U1, integrated circuit U3 Pin 1 and pin 3 are connected to both ends of C8, pin 4 and pin 5 are connected to both ends of C9, pin 2 is connected to one end of C10, pin 16 is connected to the other end of C10 and the positive pole of the 5V power supply, and pin 6 is connected to one end of C11 , 15 pins and the other end of C11 and 5 pins of socket RS-1 are grounded, 7 pins are connected to 2 pins of socket RS-1, 8 pins are connected to 3 pins of socket RS-1, and socket RS-1 is used to connect to an external computer.

The display circuit of this embodiment is formed by connecting integrated circuits U4, R30 and R31, and the model of the integrated circuit U4 is MG-12232. Pin 5 of integrated circuit U4 is connected to pin 52 of integrated circuit U1, pin 6 is connected to pin 47 of integrated circuit U1, pin 7 is connected to pin 44 of integrated circuit U1, pin 8 is connected to pin 40 of integrated circuit U1, pin 9 is connected to pin 40 of integrated circuit U1 73 pins, 10 pins connected to 65 pins of integrated circuit U1, 11 pins connected to 62 pins of integrated circuit U1, 12 pins connected to 59 pins of integrated circuit U1, 13 pins connected to 55 pins of integrated circuit U1, 14 pins connected to integrated circuit U1 Pin 46, pin 15 are connected to pin 38 of integrated circuit U1, pin 16 is connected to pin 88 of integrated circuit U1, pin 3 is connected to the positive pole of 5V power supply through R31, pin 17 is connected to the positive pole of 5V power supply through R30, pin 2 and pin 18 are grounded.

The working principle of the utility model is as follows:

The zero-sequence current input circuit mainly transforms, regulates, and inputs the zero-sequence current. The input zero-sequence current is converted into a voltage signal by R13, filtered by the filter connected by C6 and R11, and the bias circuit connected by the integrated circuit U2B, R11, R10, R9 and R8 turns the voltage signal into unipolar, The scale is adjusted by the proportional regulator connected with the integrated circuit U2A, R7, R6, and R5, and input from the 107 pin of the integrated circuit U1. The zero-sequence voltage input circuit mainly regulates and inputs the zero-sequence voltage. The input zero-sequence voltage is filtered by the filter connected by C7 and R22, and the bias circuit connected by the integrated circuit U2D, R21, R20, R19, and R18 changes the zero-sequence voltage into unipolarity, and passes through the integrated circuit U2C, R17, and R16 , The proportional regulator connected to R15 adjusts the size and is input from the 109 pin of the integrated circuit U1.

The integrated circuit U1 sends a resistor input signal through pin 81, and puts an additional resistor into a certain phase of the grid under test; the integrated circuit U1 detects the input zero-sequence voltage and zero-sequence current through the built-in A/D converter, and uses the set Calculate the insulation resistance and capacitance to ground of the power grid through a predetermined program. The integrated circuit U1 can realize the exchange of measurement results and control information between the upper microcomputer and the utility model through the serial communication circuit through pins 26 and 27. The integrated circuit U1 and the keyboard circuit can realize the input of command signals such as parameter setting, selection of the operation mode of the measurement grid, and query of measurement results. The IOPE0-IOPE7 ports of the integrated circuit U1 output the measurement results of the grid insulation resistance and the operating status of the utility model to the integrated circuit U4 for display.

Claims (5)

1, a kind of line insulation impedance detection device is characterized in that it comprises:

The DSP application system that complete machine is controlled;

The zero-sequence current input circuit, the output termination DSP application system of this circuit;

The residual voltage input circuit, the output termination DSP application system of this circuit;

The keyboard input circuit, the output termination DSP application system of this circuit;

Serial communication circuit, this circuit is connected in the DSP application system;

It also comprises display circuit, the input termination DSP application system of this circuit.

2, according to the described line insulation impedance detection of claim 1 device, it is characterized in that said zero-sequence current input circuit is: the zero sequence current signal of input passes through R12, R11 is from the inverting input input of integrated circuit U2B, the in-phase input end of integrated circuit U2B is by R9 ground connection, inverting input connects the 2.5V positive source and connects output terminal by R8 by R10, output terminal connects the inverting input of integrated circuit U2A and connects inverting input by R8 by R7, the end of the termination R12 of R13, other end ground connection, the other end of the termination R12 of C6, other end ground connection, the in-phase input end of integrated circuit U2A is by R6 ground connection, inverting input connects output terminal by R5, output terminal connects the DSP application system by R4,4 pin connect the 3.3V positive source, 11 pin connect the 3.3V power cathode.

3, according to the described line insulation impedance detection of claim 1 device, it is characterized in that said residual voltage input circuit is: the residual voltage signal of input passes through R22, R21 is from the inverting input input of integrated circuit U2D, the in-phase input end of integrated circuit U2D is by R19 ground connection, inverting input connects the 2.5V positive source and connects output terminal by R18 by R20, output terminal connects the inverting input of integrated circuit U2C by R17, between the termination R21 and R22 of C7, other end ground connection, the in-phase input end of integrated circuit U2C is by R16 ground connection, inverting input connects output terminal by R15, output terminal connects the DSP application system by R14.

4, according to the described line insulation impedance detection of claim 2 device, it is characterized in that: the model of said integrated circuit U2A and integrated circuit U2B is MCP604.

5, according to the described line insulation impedance detection of claim 3 device, it is characterized in that: the model of said integrated circuit U2C and integrated circuit U2D is MCP604.

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