CN220795433U - Differential harmonic leakage current detection device - Google Patents
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- CN220795433U CN220795433U CN202322496937.XU CN202322496937U CN220795433U CN 220795433 U CN220795433 U CN 220795433U CN 202322496937 U CN202322496937 U CN 202322496937U CN 220795433 U CN220795433 U CN 220795433U
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Abstract
The utility model discloses a differential harmonic leakage current detection device which comprises a differential leakage current measurement unit with a double-magnetic-core structure, a leakage current measurement signal conditioning circuit, a leakage current signal calculation unit and a communication transmission circuit, wherein a leakage current signal is obtained through the differential leakage current measurement unit, the leakage current measurement signal conditioning circuit amplifies and conditions the leakage current signal and outputs a detection signal and a compensation signal, the leakage current calculation unit converts the detection signal and the compensation signal into digital signals corresponding to relevant information of the leakage current, and the communication transmission circuit converts the digital signals corresponding to the relevant information of the leakage current into communication differential signals to be transmitted to external equipment or a system.
Description
Technical Field
The utility model relates to the technical field of power equipment detection, in particular to a differential harmonic leakage current detection device.
Background
The differential harmonic leakage current detection device is used for detecting the insulation level of electrical equipment, the traditional differential protection of a power transformer reflects leakage current flowing in the insulation of the winding to the ground by measuring the difference of load current at an inlet and outlet line, however, the leakage current is smaller in amplitude and is interfered by a strong magnetic field generated by hundred-ampere-level load current, and the traditional differential protection technology is generally sensitive to ampere-level current measurement.
Disclosure of utility model
The utility model aims to provide a differential harmonic leakage current detection device, which solves the problem of how to improve the detection precision and sensitivity of differential leakage current, and provides the following technical scheme for realizing the purpose:
The utility model provides a differential harmonic leakage current detection device, includes differential leakage current measurement unit, leakage current measurement signal conditioning circuit, leakage current signal calculation unit and the communication transmission circuit of two magnetic core structures, differential leakage current measurement unit's output is connected with leakage current measurement signal conditioning circuit's input electricity, leakage current measurement signal conditioning circuit's output is connected with leakage current signal calculation unit's input electricity, leakage current signal calculation unit's output is connected with communication transmission circuit's input electricity, wherein:
The leakage current measuring unit comprises a detection magnetic core, a shielding magnetic core, a zero magnetic flux detection coil and a zero magnetic flux compensation coil, and is used for measuring leakage current to obtain a leakage current signal;
The leakage current measurement signal conditioning circuit comprises an operational amplifying circuit, a detection circuit and a compensation circuit, wherein the operational amplifying circuit is used for amplifying and conditioning a leakage current signal transmitted by the leakage current measurement unit and outputting a detection signal and a compensation signal;
The leakage current calculation unit comprises an analog-to-digital converter and a microprocessor, wherein the analog-to-digital converter is used for converting the detection signal and the compensation signal into corresponding digital signals, and the digital signals are input into the microprocessor to obtain related information of leakage current;
The communication transmission circuit includes a communication integrated circuit and a communication terminal for transmitting information about the leakage current to an external device or system.
Preferably, the differential harmonic leakage current detection device further comprises a support base, a metal partition plate, an incoming cable and an outgoing cable perforation, wherein a double-magnetic core structure is connected above the support base, and the metal partition plate is wrapped on two sides of the double-magnetic core structure, wherein:
the incoming cable and the outgoing cable of the double-magnetic-core structure respectively pass through the central area of the detection magnetic core, the shielding magnetic core is nested inside the detection magnetic core, the zero magnetic flux detection coil and the zero magnetic flux compensation coil are used as outgoing wires, and the zero magnetic flux detection coil and the zero magnetic flux compensation coil are wound outside the shielding magnetic core in a twisted pair mode.
Preferably, the zero magnetic flux detection coil and the zero magnetic flux compensation coil have the same number of turns and are wound outside the shielding magnetic core in an equidistant double-strand parallel winding mode.
Preferably, the input end of the detection signal operational amplification circuit is connected with a zero magnetic flux detection coil, and the detection signal operational amplification circuit comprises filter capacitors C1 and C6, voltage stabilizing capacitors C2, C3, C4 and C5, balance resistors R1 and R2, grounding resistors R3 and R6, a feedback resistor R4, output resistors R5 and R7, amplifying chips U1A and U2A and a clamping diode D1, wherein:
the filter capacitor C1 is connected with the input end of the operational amplifier circuit;
One end of the balance resistor R1 is connected with one end of the filter capacitor C1, the other end of the balance resistor R1 is connected with the positive input end of the amplifying chip U1A, the negative input end of the amplifying chip U1A is connected with the other end of the filter capacitor C1 through the grounding resistor R3, and the output end of the amplifying chip U1A is connected with the negative input end of the amplifying chip U1A through the feedback resistor R4;
The output end of the amplifying chip U1A is also connected with the positive input end of the amplifying chip U2A through an output resistor R5, and the output resistor R5 is connected with a ground node through a grounding resistor R6;
The output end of the amplifying chip U2A is connected with one end of a filter capacitor C6 and the middle point of a clamping diode D1 through an output resistor R7, the other end of the filter capacitor C6 is connected with a ground node, and the negative input end of the amplifying chip U2A is connected with the output end of the amplifying chip U2A;
The two ends of the voltage stabilizing capacitor C2 are respectively connected with a voltage source and the positive input end of the amplifying chip U1A, the balance resistor R2 is connected with the voltage stabilizing capacitor C2 in parallel, and the two ends of the voltage stabilizing capacitors C3, C4 and C5 are respectively connected with different voltage sources and ground nodes.
Preferably, the input end of the compensation signal operational amplification circuit is connected with the zero magnetic flux compensation coil, and the compensation signal operational amplification circuit and the detection signal amplification circuit have the same topological structure.
Preferably, the communication terminal is any one of an RS232 interface, an RS485 interface, an ethernet RJ45 interface, a wireless interface, a bluetooth module or a Wi-Fi module.
Compared with the prior art, the utility model has the beneficial effects that:
1. the application relates to a differential harmonic leakage current detection device, wherein a differential leakage current measurement unit is of a double-magnetic-core structure, an incoming cable and an outgoing cable of the double-magnetic-core structure respectively pass through the central area of a detection magnetic core, a shielding magnetic core is nested inside the detection magnetic core, the number of turns of a zero magnetic flux detection coil and a zero magnetic flux compensation coil are equal, the zero magnetic flux detection coil and the zero magnetic flux compensation coil are wound outside the shielding magnetic core in an equidistant double-strand parallel winding mode, and the zero magnetic flux detection coil and the zero magnetic flux compensation coil can effectively induce and offset a magnetic field generated by leakage current in a double-strand parallel winding mode, so that the sensitivity and the responsiveness of the coil are improved, the conduction interference and noise are effectively eliminated, and the accurate and reliable zero magnetic flux detection is realized;
2. The application relates to a differential harmonic leakage current detection device, which is used for detecting leakage current through a zero magnetic flux principle, has high response speed and can timely capture magnetic field change; the detection sensitivity to the micro magnetic field in the magnetic core is high, and the magnetic field of differential leakage current can be accurately measured; the device is not influenced by the change of the resistance parameter of the coil, and can maintain stable measurement performance; the method is not influenced by the distribution parameters among the coils, and a reliable measurement result can be provided;
3. The application relates to a differential harmonic leakage current detection device, which comprises a support base and a metal partition plate, wherein the protection and stable support are provided, and the normal operation and the reliability of the detection device are ensured.
Drawings
FIG. 1 is a schematic circuit diagram of the device of the present utility model;
FIG. 2 is a diagram of an operational amplifier circuit of a detection signal according to the present utility model;
Fig. 3 is a design drawing of a dual core structure of the present utility model.
Detailed Description
The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
Example 1
Referring to fig. 1, the present embodiment provides a technical solution:
the utility model provides a differential harmonic leakage current detection device, includes differential leakage current measurement unit, leakage current measurement signal conditioning circuit, leakage current signal calculation unit and the communication transmission circuit of two magnetic core structures, and is still further:
The differential harmonic leakage current detection device also comprises a support base, a metal partition plate, an incoming cable and an outgoing cable perforation, wherein a double-magnetic-core structure is connected above the support base, the metal partition plates are wrapped on two sides of the double-magnetic-core structure, the metal parts are used for providing protection and stable support so as to ensure the normal operation and reliability of the detection device, the support base and the metal partition plate form a metal shell, and reliable protection is provided for an internal key element, namely a differential leakage current measurement unit of the double-magnetic-core structure through the structural design of the shell, and the differential leakage current measurement unit is prevented from being interfered by physical damage or environmental factors; meanwhile, the metal material has good mechanical strength and corrosion resistance, and can effectively resist external impact and erosion, so that the sensing device is protected from being damaged;
The leakage current measuring unit comprises a detection magnetic core, a shielding magnetic core, a zero magnetic flux detection coil and a zero magnetic flux compensation coil, and is used for measuring leakage current to obtain a leakage current signal, wherein the leakage current signal comprises a leakage current sampling detection signal and a leakage current sampling compensation signal;
Firstly, determining magnetic core materials of a shielding magnetic core and a detection magnetic core, in the embodiment, selecting a 1J85 permalloy strip with the thickness of 0.1mm, and stacking the 1J85 permalloy strip into a round magnetic core, wherein the magnetic core materials have higher magnetic permeability and low hysteresis loss, so that the performance of a magnetic field sensor can be effectively enhanced; the shielding magnetic core and the detecting magnetic core are coaxial circular rings, a closed design is adopted, the inner diameter of the detecting magnetic core is similar to the outer diameter of the shielding magnetic core, and the shielding magnetic core is nested inside the detecting magnetic core;
Secondly, determining the size parameters of the shielding magnetic core and the detecting magnetic core, and in the embodiment, designing by a magnetic field distribution analysis model based on a double-magnetic-core structure so as to meet the following requirements: 1) Effectively shielding the magnetic field of 400A load current; 2) High-sensitivity measurement of 1mA leakage current is realized; 3) The axial thickness of the shielding magnetic core is ensured to be larger than that of the detecting magnetic core, the influence of the magnetic field of the end part of the carrier fluid on the magnetic field distribution of the detecting magnetic core is reduced, the volume and consumable factors of the sensing device are comprehensively considered, and the structure and the size design parameters of the double-magnetic-core current sensor are shown in the figure 3;
The method comprises the steps that a wire inlet cable and a wire outlet cable of a double-magnetic-core structure respectively pass through a center area of a detection magnetic core, positions of the wire inlet cable and the wire outlet cable, namely b 'and b', are determined, the distance between the wire inlet cable and the wire outlet cable meets an insulation distance determined according to a voltage level of a power device, the wire inlet cable and the wire outlet cable pass through the inside of the shielding magnetic core, fixed positions are arranged in a center-symmetrical mode, a single-core copper cable is adopted in a low-voltage heavy-current test environment and is enabled to bear larger current in an air laying mode, a current-carrying conductor fixing device is designed, b '=b', the aperture is slightly larger than (b '+b'), in the embodiment, a single-core copper cable ZR-YJV-1kV with the sectional area of 185mm 2 and the outer diameter of 22.92mm is adopted in the low-voltage heavy-current test environment, and in order to fix the current-carrying conductor, in the embodiment, the device is placed at a position of 13.2mm away from the current-carrying conductor and fixed by using an aperture of 25mm, and the distance between the wire inlet cable and the wire outlet cable is ensured to meet the insulation distance determined according to the voltage level of the power device;
The zero magnetic flux detection coil and the zero magnetic flux compensation coil are used as outgoing wires and are wound outside the shielding magnetic core in a twisted pair mode, and preferably, the zero magnetic flux detection coil and the zero magnetic flux compensation coil have equal turns and are wound outside the shielding magnetic core in an equidistant double-strand parallel winding mode; specifically, the windings of the zero-flux detecting coil and the zero-flux compensating coil are respectively composed of two wires which pass through the hollow center of the magnetic core alternately in parallel around the magnetic core to form a compact coil structure, and the winding intervals of the zero-flux detecting coil and the zero-flux compensating coil are equal and constant for maintaining uniformity, which means that the distances between the adjacent two windings on each coil are the same to ensure uniformity and stability of the coils; by the double-strand parallel winding mode, the zero-magnetic-flux detection coil and the zero-magnetic-flux compensation coil can effectively sense and offset a magnetic field generated by leakage current, improve the sensitivity and the responsiveness of the coil, effectively eliminate conduction interference and noise and realize accurate and reliable zero-magnetic-flux detection;
Preferably, the magnetic induction intensity of the differential leakage current magnetic field is generally in the order of hundreds of uT to mT, in order to realize accurate measurement of the micro magnetic field signal, the device in the embodiment performs leakage detection according to the zero magnetic flux principle, selects a twisted pair with skin depth meeting the requirement of frequency bandwidth, and particularly selects a twisted pair with diameter of 0.5mm as a coil material in the embodiment, wherein the skin depth of the coil can meet the requirement of 100kHz frequency bandwidth. The measuring method based on the zero magnetic flux principle has the following advantages: 1) The response speed is high, and the magnetic field change can be captured in time; 2) The detection sensitivity to the micro magnetic field in the magnetic core is high, and the magnetic field of differential leakage current can be accurately measured; 3) The device is not influenced by the change of the resistance parameter of the coil, and can maintain stable measurement performance; 4) And the method is not influenced by the distribution parameters among the coils, and can provide reliable measurement results. By adopting the measuring method based on the zero magnetic flux principle, the embodiment can realize accurate detection and high-precision measurement of the differential leakage current magnetic field;
In this embodiment, an induced electromotive force corresponding to the leakage current is generated in the zero-flux detection coil, and an induced electromotive force having the same magnitude but opposite directions is generated in the zero-flux compensation coil; the design of the embodiment enables the induced electromotive forces of the two coils to cancel each other, the total magnetic flux in the whole system is zero, namely no residual magnetic field exists, and the detection magnetic core is in a zero magnetic flux state; by the zero magnetic flux detection method, the embodiment can eliminate the residual magnetic field in the magnetic core, ensure accurate magnetic field measurement and improve the stability and accuracy of a measurement system;
The output end of the differential leakage current measuring unit is electrically connected with the input end of the leakage current measuring signal conditioning circuit;
The leakage current measurement signal conditioning circuit comprises an operational amplifying circuit, a detection circuit and a compensation circuit, wherein the operational amplifying circuit is used for amplifying and conditioning a leakage current signal transmitted by the leakage current measurement unit and outputting a detection signal and a compensation signal;
Preferably, the input end of the operational amplification circuit is connected with a zero magnetic flux detection coil and a zero magnetic flux compensation coil, and the operational amplification circuit comprises filter capacitors C1 and C6, stabilizing capacitors C2, C3, C4 and C5, balancing resistors R1 and R2, grounding resistors R3 and R6, a feedback resistor R4, output resistors R5 and R7, amplifying chips U1A and U2A and a clamping diode D1, wherein:
the filter capacitor C1 is connected with the input end of the operational amplifier circuit;
One end of the balance resistor R1 is connected with one end of the filter capacitor C1, the other end of the balance resistor R1 is connected with the positive input end of the amplifying chip U1A, leakage current sampling detection signals are converted into voltage signals, the negative input end of the amplifying chip U1A is connected with the other end of the filter capacitor C1 through the grounding resistor R3, and the output end of the amplifying chip U1A is connected with the negative input end of the amplifying chip U1A through the feedback resistor R4;
The output end of the amplifying chip U1A is also connected with the positive input end of the amplifying chip U2A through an output resistor R5, and the output resistor R5 is connected with a ground node through a grounding resistor R6;
The output end of the amplifying chip U2A is connected with one end of a filter capacitor C6 and the middle point of a clamping diode D1 through an output resistor R7, the other end of the filter capacitor C6 is connected with a ground node, and the negative input end of the amplifying chip U2A is connected with the output end of the amplifying chip U2A;
Preferably, the amplifying chip U2A is used as a voltage follower, the output resistor R7 and the filter capacitor C6 together form a first-order low-pass filter, and the clamping diode is used for preventing the output voltage of the amplifying chip U2A from being too large so as to protect the amplifying chip U2A;
The two ends of the voltage stabilizing capacitor C2 are respectively connected with a +2.5V voltage source and the positive input end of the amplifying chip U1A, the balance resistor R2 is connected in parallel with the voltage stabilizing capacitor C2, the two ends of the voltage stabilizing capacitor C3 are respectively connected with a +15V voltage source and a ground node, the two ends of the voltage stabilizing capacitor C4 are respectively connected with a-15V voltage source and a ground node, the two ends of the voltage stabilizing capacitor C5 are respectively connected with a +5V voltage source and a ground node, and the voltage stabilizing capacitors C3, C4 and C5 respectively provide power for the amplifying chip U1A and the amplifying chip U2A;
Preferably, the input end of the compensation signal operational amplification circuit is connected with a zero magnetic flux compensation coil, the compensation signal operational amplification circuit and the detection signal amplification circuit have the same topology structure, specifically, in this embodiment, the corresponding relationship between the topology structures of the compensation signal operational amplification circuit and the detection signal amplification circuit is that filter capacitors C7 and C12 correspond to C1 and C6, voltage stabilizing capacitors C8, C9, C10 and C11 correspond to C2, C3, C4 and C5, balancing resistors R8 and R9 correspond to R1 and R2, grounding resistors R10 and R13 correspond to R3 and R6, feedback resistor R11 corresponds to R4, output resistors R12 and R14 correspond to R5 and R7, amplifying chips U3A and U4A correspond to U1A and U2A, and clamping diode D2 corresponds to D1.
The output end of the leakage current measurement signal conditioning circuit is electrically connected with the input end of the leakage current signal calculation unit;
The leakage current calculation unit comprises an analog-to-digital converter and a microprocessor, wherein the analog-to-digital converter is used for converting the detection signal and the compensation signal into corresponding digital signals, and the digital signals are input into the microprocessor to obtain related information of leakage current;
the output end of the leakage current signal calculation unit is electrically connected with the input end of the communication transmission circuit, wherein:
the communication transmission circuit comprises a communication integrated circuit and a communication terminal, and is used for transmitting relevant information of leakage current to external equipment or a system;
Preferably, the communication integrated circuit is a 485 communication module, and is connected with a communication terminal via a twisted pair (A line and B line which are mutually differential signals, and a balance resistor R15 is connected between the A line and the B line), and the communication terminal is any one of an RS232 interface, an RS485 interface, an Ethernet RJ45 interface, a wireless interface, a Bluetooth module or a Wi-Fi module.
The embodiment provides a differential harmonic leakage current detection device, which comprises a differential leakage current measurement unit with a double-magnetic-core structure, a leakage current measurement signal conditioning circuit, a leakage current signal calculation unit and a communication transmission circuit, wherein a leakage current signal is obtained through the differential leakage current measurement unit, the leakage current measurement signal conditioning circuit amplifies and conditions the leakage current signal and outputs a detection signal and a compensation signal, the leakage current calculation unit converts the detection signal and the compensation signal into digital signals corresponding to relevant information of the leakage current, and the communication transmission circuit converts the digital signals corresponding to the relevant information of the leakage current into communication differential signals to be transmitted to external equipment or a system.
Although the present utility model has been described with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements and changes may be made without departing from the spirit and principles of the present utility model.
Claims (6)
1. The utility model provides a differential harmonic leakage current detection device, its characterized in that includes the differential leakage current measurement unit of two magnetic core structures, leakage current measurement signal conditioning circuit, leakage current signal calculation unit and communication transmission circuit, the output of differential leakage current measurement unit is connected with the input of leakage current measurement signal conditioning circuit, the output of leakage current measurement signal conditioning circuit is connected with the input of leakage current signal calculation unit electricity, the output of leakage current signal calculation unit is connected with the input of communication transmission circuit electricity, wherein:
The leakage current measuring unit comprises a detection magnetic core, a shielding magnetic core, a zero magnetic flux detection coil and a zero magnetic flux compensation coil, and is used for measuring leakage current to obtain a leakage current signal;
the leakage current measurement signal conditioning circuit comprises a detection signal operational amplification circuit and a compensation signal operational amplification circuit, and is used for amplifying and conditioning the leakage current signal transmitted by the leakage current measurement unit and outputting a detection signal and a compensation signal;
The leakage current calculation unit comprises an analog-to-digital converter and a microprocessor, wherein the analog-to-digital converter is used for converting the detection signal and the compensation signal into corresponding digital signals, and the digital signals are input into the microprocessor to obtain related information of leakage current;
The communication transmission circuit includes a communication integrated circuit and a communication terminal for transmitting information about the leakage current to an external device or system.
2. The differential harmonic leakage current detection device according to claim 1, further comprising a support base, a metal separator, an incoming cable and an outgoing cable perforation, wherein a dual magnetic core structure is connected above the support base, and metal separators are wrapped on two sides of the dual magnetic core structure, wherein:
the incoming cable and the outgoing cable of the double-magnetic-core structure respectively pass through the central area of the detection magnetic core, the shielding magnetic core is nested inside the detection magnetic core, the zero magnetic flux detection coil and the zero magnetic flux compensation coil are used as outgoing wires, and the zero magnetic flux detection coil and the zero magnetic flux compensation coil are wound outside the shielding magnetic core in a twisted pair mode.
3. The differential harmonic leakage current detection device according to claim 2, wherein the zero-flux detection coil and the zero-flux compensation coil have the same number of turns and are wound around the shielding core in an equally spaced double-stranded parallel winding manner.
4. The differential harmonic leakage current detection device according to claim 1, wherein the input terminal of the detection signal operational amplification circuit is connected to a zero magnetic flux detection coil, and comprises filter capacitors C1 and C6, voltage stabilizing capacitors C2, C3, C4 and C5, balancing resistors R1 and R2, grounding resistors R3 and R6, feedback resistor R4, output resistors R5 and R7, amplification chips U1A and U2A, and a clamping diode D1, wherein:
the filter capacitor C1 is connected with the input end of the operational amplifier circuit;
One end of the balance resistor R1 is connected with one end of the filter capacitor C1, the other end of the balance resistor R1 is connected with the positive input end of the amplifying chip U1A, the negative input end of the amplifying chip U1A is connected with the other end of the filter capacitor C1 through the grounding resistor R3, and the output end of the amplifying chip U1A is connected with the negative input end of the amplifying chip U1A through the feedback resistor R4;
The output end of the amplifying chip U1A is also connected with the positive input end of the amplifying chip U2A through an output resistor R5, and the output resistor R5 is connected with a ground node through a grounding resistor R6;
The output end of the amplifying chip U2A is connected with one end of a filter capacitor C6 and the middle point of a clamping diode D1 through an output resistor R7, the other end of the filter capacitor C6 is connected with a ground node, and the negative input end of the amplifying chip U2A is connected with the output end of the amplifying chip U2A;
The two ends of the voltage stabilizing capacitor C2 are respectively connected with a voltage source and the positive input end of the amplifying chip U1A, the balance resistor R2 is connected with the voltage stabilizing capacitor C2 in parallel, and the two ends of the voltage stabilizing capacitors C3, C4 and C5 are respectively connected with different voltage sources and ground nodes.
5. The differential harmonic leakage current detection device according to claim 4, wherein the input terminal of the compensation signal operational amplifier circuit is connected to the zero magnetic flux compensation coil, and the compensation signal operational amplifier circuit and the detection signal amplifier circuit have the same topology.
6. The differential harmonic leakage current detection device according to claim 1, wherein the communication terminal is any one of an RS232 interface, an RS485 interface, an ethernet RJ45 interface, a wireless interface, a bluetooth module, or a Wi-Fi module.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202322496937.XU CN220795433U (en) | 2023-09-14 | 2023-09-14 | Differential harmonic leakage current detection device |
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| CN202322496937.XU CN220795433U (en) | 2023-09-14 | 2023-09-14 | Differential harmonic leakage current detection device |
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