Secondary zero sequence voltage detection system for reconstruction of electromagnetic feeder automation terminal
By introducing input protection, signal conversion, and isolation conversion modules into the electromagnetic feeder automation terminal, and using operational amplifiers and isolation operational amplifier chips for zero-sequence voltage detection, the problem that old FTUs cannot directly utilize the original zero-sequence voltage sensor is solved, realizing low-cost direct acquisition of zero-sequence voltage and reducing the cost and complexity of the retrofit scheme.
Patent Information
- Application Number
- CN202511329885.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-17
- Publication Date
- 2025-11-07
AI Technical Summary
The old electromagnetic feeder automation terminal (FTU) lacks fault location function, and the high computing power chips in the existing retrofit scheme are expensive, making it impossible to directly use the original zero-sequence voltage sensor for zero-sequence voltage detection again.
The system employs an input protection module, a signal conversion module, an isolation conversion module, and an output module. It utilizes operational amplifiers and isolation operational amplifier chips for signal conversion and isolation, enabling hardware detection of zero-sequence voltage and meeting electrical isolation requirements.
This reduces the cost of modification, meets the electrical isolation requirements of zero-sequence voltage sensors, enables direct acquisition of zero-sequence voltage, and avoids the high cost and high heat generation problems of high-computing-power chips.
Smart Images
Figure CN120908515A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of feeder automation terminal, in particular to a re-zero sequence voltage detection system for electromagnetic feeder automation terminal reconstruction. BACKGROUND
[0002] The feeder automation terminal (FTU) is a control device of the distribution automation switch. As the distribution network in the power grid has developed for decades, a large number of automation switches are installed on the distribution line to achieve on-site isolation of faults and rapid power restoration of non-fault areas. However, the medium and low voltage distribution network is mostly a small current grounding system, and the grounding fault characteristics are weak and highly concealed. Moreover, as the power consumption increases and the number of power users increases, fault investigation and maintenance become inconvenient. With the development of distribution network technology, the FTU in the distribution network needs fault location function to shorten the power outage time and facilitate maintenance work. Many old automation switches do not have fault location function, and the actual effect of ground fault monitoring is not ideal. The current inventory of old automation switches and their matching FTU is large, and the overall replacement cost is high. Therefore, the power grid companies in various places carry out reconstruction and upgrading of existing old FTU.
[0003] The current reconstruction is to add a fault location device to the original FTU device. Both the fault location device and the FTU need to collect the zero sequence voltage signal from the zero sequence voltage sensor in the distribution automation switch. The national standard requires that the zero sequence voltage sensor has a total input impedance requirement for the subsequent acquisition circuit, which requires an input impedance greater than 2MΩ. The old electromagnetic FTU usually uses a high-impedance 10V-3.53V or 1-0.353V high-impedance transformer for signal acquisition and isolation. In the design, there is basically no consideration for the subsequent need for re-measurement of zero sequence voltage. Usually, in order to save space and cost, the minimum input impedance is designed to be 2.1MΩ, which makes it impossible to directly use the output of the existing zero sequence voltage sensor of the automation switch for subsequent collection when other manufacturers add the zero sequence voltage acquisition function again. When re-measuring the zero sequence voltage, a high-performance chip software is usually used to measure the A, B and C three-phase voltages and perform complex phasor operations to obtain the zero sequence voltage value. The high-performance chip has high cost in terms of heat dissipation, size, price and software algorithm labor input. SUMMARY
[0004] The present application relates to the technical field of feeder automation terminal, in particular to a re-zero sequence voltage detection system for electromagnetic feeder automation terminal reconstruction.
[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A re-zero sequence voltage detection system for electromagnetic feeder automation terminal reconstruction, comprising an input protection module, a signal conversion module, an isolation conversion module and an output module; The input protection module is connected to the output end of the zero sequence voltage sensor and is used for current limiting and overvoltage protection. The signal conversion module comprises an operational amplifier unit, which is used for receiving the signal of the input protection module and converting the positive and negative alternating voltage output by the zero sequence voltage sensor into a positive voltage signal through a reference source. The isolation conversion module comprises an isolation operational amplifier unit, which is used for electrically isolating the output of the signal conversion module. The output module comprises a differential to single-ended circuit unit, which is used for converting the isolated differential signal into a single-ended voltage signal to connect an external acquisition device.
[0006] In a possible implementation, the input protection module comprises a current limiting protection resistor, the resistance value of the current limiting protection resistor is 1KΩ, and the current limiting protection resistor is directly connected to the output end of the zero sequence voltage sensor for limiting the input current.
[0007] In a possible implementation, the operational amplifier unit of the signal conversion module comprises a first operational amplifier and a second operational amplifier; the first operational amplifier is configured as a voltage follower and is used for transforming high-impedance input into low-impedance output; and the second operational amplifier is configured with a gain reduction and voltage lifting circuit.
[0008] In a possible implementation, the gain reduction and voltage lifting circuit of the second operational amplifier comprises a first resistor, a second resistor, a third resistor and a fourth resistor; wherein the resistance values of the first resistor and the third resistor are 90KΩ, and the resistance values of the second resistor and the fourth resistor are 10KΩ.
[0009] In a possible implementation, the isolation operational amplifier unit of the isolation conversion module adopts an isolation operational amplifier chip, which is used for realizing signal isolation through digital modulation and demodulation; and the differential to single-ended circuit unit of the output module comprises a third operational amplifier and a plurality of matched resistors, which are used for converting the isolated differential output into a single-ended voltage.
[0010] In a possible implementation, an overvoltage protection device is further included, the overvoltage protection device is a gas discharge tube or a voltage-dependent resistor, and is connected between the output end of the zero sequence voltage sensor and the input protection module, and is used for suppressing high-voltage pulse interference.
[0011] In a possible implementation, the single-ended voltage signal output end of the output module is connected to an analog-to-digital converter interface of a microcontroller, which is used for subsequent data acquisition and processing.
[0012] Compared with the prior art, the present application has the following advantages: 1. By using electronic devices such as electronic operational amplifiers to replace traditional pure software methods, the required electrical isolation requirements are met, and expensive, bulky, high-heat, and high-labor-cost high-computing-power chip software calculations are not needed to operate the zero-sequence voltage to obtain results; that is, a hardware method is used to replace a traditional software method.
[0013] 2. The operational amplifier chip and the isolated operational amplifier chip are used, and the high input impedance characteristic of the operational amplifier is used to satisfy the requirement of 2M ohm impedance of the distribution network electromagnetic transformer after the ohmic parallel connection of the high impedance transformer of the FTU. 3. The operational amplifier is used to perform signal transformation on the input signal, the positive and negative AC voltage output by the zero-sequence voltage sensor of the automation switch is improved through a reference source and converted into a positive voltage through the operational amplifier, the positive voltage is isolated and converted into a single-ended voltage through the isolated operational amplifier and the differential-to-single-ended circuit, and the single-ended voltage can be directly collected and used by the collection device. BRIEF DESCRIPTION OF DRAWINGS
[0014] Fig. 1 is a schematic diagram of the overall structure of the present application; Fig. 2 is a schematic diagram of the circuit structure of the present application; Fig. 3 is a structure diagram of the MCU microcontroller U4A connected with the present application. DETAILED DESCRIPTION
[0015] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the specific embodiments, structures, features, and effects of the present application will be described in detail below in combination with the drawings and preferred embodiments.
[0016] As shown in Figs. 1-3 , a re-zero-sequence voltage detection system for electromagnetic feeder automation terminal modification includes an input protection module 10, a signal transformation module 20, an isolation conversion module 30, and an output module 40. The input protection module 10 is connected to the output end of the zero-sequence voltage sensor and is used for current limiting and overvoltage protection; it includes a current limiting protection resistor R5, the resistance value of the current limiting protection resistor R5 is 1KΩ, and the precision is 1%, the current limiting protection resistor R5 is directly connected to the output end of the zero-sequence voltage sensor.
[0017] The signal transformation module 20 includes an operational amplifier unit, is used for receiving the signal of the input protection module, and converts the positive and negative AC voltage output by the zero-sequence voltage sensor into a positive voltage signal through a reference source; The operation amplifier unit comprises a first operation amplifier U1A and a second operation amplifier U1B; the first operation amplifier U1A is configured as a voltage follower for transforming from high impedance input to low impedance output; the second operation amplifier U1B is configured with a gain reduction and voltage lifting circuit comprising a plurality of precision resistors for reducing the input signal by 10 times and lifting the signal to a common-mode voltage of 1.024V by a 1.024V reference source.
[0018] Specifically, the gain reduction and voltage lifting circuit comprises a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4; wherein the first resistor R1 and the third resistor R3 have a resistance of 90KΩ and an accuracy of 0.1%, and the second resistor R2 and the fourth resistor R4 have a resistance of 10KΩ and an accuracy of 0.1%; the precision resistors collectively realize accurate scaling and biasing of the input signal.
[0019] The isolation conversion module 30 comprises an isolation operation amplifier unit for electrically isolating the output of the signal conversion module; the isolation operation amplifier unit adopts an isolation operation amplifier chip U2 for realizing signal isolation through digital modulation and demodulation; The output module 40 comprises a differential-to-single-ended circuit unit for converting the isolated differential signal into a single-ended voltage signal to connect an external acquisition device; wherein the differential-to-single-ended circuit unit comprises a third operation amplifier U3 and a plurality of matched resistors for converting the isolated differential output into a single-ended voltage; the matched resistors are R6-R9, each having a resistance of 10KΩ and an accuracy of 0.1%.
[0020] In the present application, the operation amplifier unit has an input impedance of 100GΩ or above, and after being connected in parallel with the original high-impedance mutual inductor of the electromagnetic feeder terminal unit (FTU), the total impedance meets the requirement of 2MΩ of the distribution network; the reference source is 1.024V for lifting the input signal by 1.024V and reducing the gain by 10 times.
[0021] Further, the zero-sequence voltage detection system of the present application further comprises an overvoltage protection device, which is a gas discharge tube GDT1 or a voltage-dependent resistor, connected between the output end of the zero-sequence voltage sensor and the input protection module, for suppressing high-voltage pulse interference.
[0022] The single-ended voltage signal output end of the output module is connected to the analog-to-digital converter ADC interface of the microcontroller U4A for subsequent data acquisition and processing; wherein the microcontroller is configured to output to an external acquisition module through a general-purpose input / output interface (such as PA9 and PA10).
[0023] In use, the output end of the zero sequence voltage sensor is electrically connected to R5, and the detection system of the application outputs the value of the zero sequence voltage amplitude after being reduced by 10 times and the voltage being raised by 1.024V as a whole to the ADC interface of the microcontroller U4A through the pin (the pin marked as No. 5 in the figure) of the third amplifier U3, and then outputs to other supporting collection modules through the output interfaces PA9 and PA10 on the first control chip U4A.
[0024] In the application, the chip of the first operational amplifier U1A and the chip of the second operational amplifier U1B adopt the OPA2991IDR chip of the prior art of TI company, the isolation operational amplifier chip U2 adopts the CA-IS1311BG chip of the Chuantu Micro company, the chip of the third operational amplifier U3 selects the TLV9061IDBVR of TI company, and the control chip U4A adopts the STM32L431RCT6 of ST company.
[0025] In the description of the application, it should be understood that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inner", "front", "central", "both ends", "left and right", "front and back" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.
[0026] In the application, unless otherwise explicitly specified and limited, the terms "mounting", "setting", "connecting", "fixing", "threading" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrated; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited, the above-mentioned terms in the application can be understood according to the specific meaning of the above-mentioned terms in the application by those skilled in the art.
[0027] The above is only the preferred embodiment of the application, and does not limit the application in any form, although the application has been disclosed as above with the preferred embodiment, however, it is not intended to limit the application, any person skilled in the art can make some changes or modifications to the above-mentioned disclosed technical content without departing from the scope of the technical scheme of the application, and make equivalent embodiments with equivalent changes, as long as it does not depart from the technical scheme of the application, any indirect modification, equivalent change and modification of the above-mentioned embodiments according to the technical essence of the application are within the scope of the technical scheme of the application.
Claims
1. A re-zero sequence voltage detection system for electromagnetic feeder automation terminal retrofit, characterized in that, The input protection module, the signal conversion module, the isolation conversion module and the output module are included. The input protection module is connected with the output end of the zero sequence voltage sensor and is used for current limiting and overvoltage protection. The signal conversion module includes an operational amplifier unit, which is used for receiving the signal of the input protection module and converting the positive and negative alternating voltage output by the zero sequence voltage sensor into a positive voltage signal through a reference source. The isolation conversion module includes an isolation operational amplifier unit, which is used for electrically isolating the output of the signal conversion module. The output module includes a differential-to-single-ended circuit unit, which is used for converting the isolated differential signal into a single-ended voltage signal to connect an external acquisition device.
2. The re-zero sequence voltage detection system for electromagnetic feeder automation terminal retrofit of claim 1, wherein, The input protection module includes a current limiting protection resistor, the resistance value of which is 1KΩ, and the current limiting protection resistor is directly connected with the output end of the zero sequence voltage sensor and is used for limiting the input current.
3. The re-zero sequence voltage detection system for electromagnetic feeder automation terminal retrofit of claim 1, wherein, The operational amplifier unit of the signal conversion module includes a first operational amplifier and a second operational amplifier; the first operational amplifier is configured as a voltage follower and is used for transforming high-impedance input into low-impedance output; and the second operational amplifier is configured with a gain reduction and voltage lifting circuit.
4. The re-zero sequence voltage detection system for electromagnetic feeder automation terminal retrofit of claim 3, wherein, The gain reduction and voltage lifting circuit of the second operational amplifier includes a first resistor, a second resistor, a third resistor and a fourth resistor; the resistance value of the first resistor and the third resistor is 90KΩ, and the resistance value of the second resistor and the fourth resistor is 10KΩ.
5. The re-zero sequence voltage detection system for electromagnetic feeder automation terminal retrofit of claim 1, wherein, The isolation operational amplifier unit of the isolation conversion module adopts an isolation operational amplifier chip and is used for realizing signal isolation through digital modulation and demodulation; and the differential-to-single-ended circuit unit of the output module includes a third operational amplifier and a plurality of matched resistors and is used for converting the isolated differential output into a single-ended voltage.
6. The re-zero sequence voltage detection system for electromagnetic feeder automation terminal retrofit of claim 1, wherein, An overvoltage protection device is further included, which is a gas discharge tube or a voltage-dependent resistor and is connected between the output end of the zero sequence voltage sensor and the input protection module and is used for suppressing high-voltage pulse interference.
7. The re-zero sequence voltage detection system for electromagnetic feeder automation terminal retrofit of claim 1, wherein, The single-ended voltage signal output end of the output module is connected with the analog-to-digital converter interface of a microcontroller and is used for subsequent data acquisition and processing.