Power failure detection circuit for distribution automation terminal

Abstract

The utility model discloses a power failure detection circuit used for a power distribution automation terminal. The power failure detection circuit comprises a lightning stroke surge protection module, a threshold setting module, a signal isolation module and a signal retardation module. The lightning stroke surge protection module is connected with a power supply voltage input end, the lightning stroke surge protection module is connected with the signal isolation module, the signal isolation module is respectively connected with the threshold setting module and the signal hysteresis module, and the threshold setting module is connected with the power supply voltage input end. According to the utility model, the technical problems of how to set the monitoring threshold according to the characteristics of the back-up power supply and how to avoid repeated oscillation of the monitoring signal are solved.

Description

Technical Field

[0001] This utility model relates to the field of power distribution automation terminal technology, and in particular to a power failure detection circuit for power distribution automation terminals. Background Technology

[0002] Distribution automation terminals are a general term for various remote monitoring and control units installed in the distribution network, performing functions such as data acquisition, control, and communication. They mainly include feeder terminals, substation terminals, and transformer terminals. Patent document CN202223409551.2 discloses a rapid power-down detection circuit and device. The anode of the primary side of the isolation optocoupler module is connected to the voltage output terminal of the power-down holding DC power supply; the cathode of the primary side of the isolation optocoupler module is connected to the voltage input terminal of the power-down holding DC power supply; the collector of the secondary side of the isolation optocoupler module is connected to the voltage output terminal of the detection power supply and the base of the detection transistor; the emitter of the secondary side of the isolation optocoupler module is grounded; the base of the detection transistor is connected to the voltage output terminal of the detection power supply; the collector of the detection transistor is connected to the voltage output terminal of the detection power supply and the main control module; the emitter of the detection transistor is grounded; and the voltage output terminal of the detection power supply is connected to the main control module. This circuit has no set power-down threshold, and the output signal is unstable, lacking surge protection and hysteresis functions. Therefore, there is an urgent need to propose a power failure detection circuit for power distribution automation terminals to solve the technical problems of how to set monitoring thresholds according to the characteristics of backup power supply and avoid repeated oscillations of monitoring signals. Utility Model Content

[0003] The main purpose of this invention is to propose a power failure detection circuit for power distribution automation terminals, aiming to solve the technical problems of how to set monitoring thresholds according to the characteristics of backup power supply and avoid repeated oscillations of monitoring signals.

[0004] To achieve the above objectives, this utility model provides a power failure detection circuit for a power distribution automation terminal, wherein the power failure detection circuit for the power distribution automation terminal includes:

[0005] Lightning surge protection module, threshold setting module, signal isolation module, and signal hysteresis module;

[0006] The lightning surge protection module is connected to the power supply voltage input terminal. The lightning surge protection module is connected to the signal isolation module. The signal isolation module is connected to the threshold setting module and the signal hysteresis module respectively. The threshold setting module is connected to the power supply voltage input terminal.

[0007] In one preferred embodiment, the lightning surge protection circuit includes a resistor R920 and a bidirectional Zener diode Z39; one end of the resistor R920 is connected to the positive terminal of the power supply voltage input, and the other end of the resistor R920 is connected to the signal isolation module and the bidirectional Zener diode Z39 respectively; the other end of the bidirectional Zener diode Z39 is connected to the negative terminal of the power supply voltage input and the signal isolation module respectively.

[0008] In one preferred embodiment, the signal isolation module includes a first filtering circuit, a current limiting circuit, and a signal isolation circuit; the first filtering circuit is electrically connected to the lightning surge protection circuit, the current limiting circuit, and the threshold setting module, respectively; the current limiting circuit is electrically connected to the signal isolation circuit; and the signal isolation circuit is electrically connected to the threshold setting module and the signal hysteresis module, respectively.

[0009] In one preferred embodiment, the first filter circuit includes capacitor C605 and capacitor C606; one end of capacitor C606 is connected to the lightning surge protection circuit, the current limiting circuit and the threshold setting module respectively, one end of capacitor C605 is connected to the current limiting circuit, and the other ends of capacitors C605 and C606 are grounded.

[0010] In one preferred embodiment, the current limiting circuit includes resistor R918 and resistor R919; one end of resistor R919 is connected to capacitor C606 and threshold setting module respectively, the other end of resistor R919 is connected to capacitor C605 and resistor R918 respectively, and the other end of resistor R918 is connected to signal isolation circuit.

[0011] In one preferred embodiment, the signal isolation circuit includes an optocoupler U53; pin 1 of the optocoupler U53 is connected to a current limiting circuit, pin 2 of the optocoupler U53 is connected to a threshold setting module, pin 3 of the optocoupler U53 is connected to resistors R921 and R922 and capacitor C607 respectively, the other end of resistor R921 is grounded, the other end of resistor R922 is connected to a signal hysteresis module, and the other end of capacitor C607 is connected to pin 4 of the optocoupler U53 and the power supply terminal respectively.

[0012] In one preferred embodiment, the threshold setting circuit includes resistor R7, resistor R16, and voltage regulator V34; pin 1 of voltage regulator V34 is connected to resistor R16 and resistor R7 respectively, the other end of resistor R7 is connected to a current limiting circuit, the other end of resistor R16 is connected to the negative terminal of the power supply voltage input, pin 2 of voltage regulator V34 is connected to a signal isolation circuit, and pin 3 of voltage regulator V34 is connected to a first filter circuit.

[0013] In one preferred embodiment, the signal hysteresis module includes a comparator U3, a MOSFET V35, resistors R26, R24, R23, and R22, a capacitor C60, a resistor R25, and a second filter circuit. The gate of the MOSFET V35 is connected to resistor R26 and the power-down signal output terminal, respectively. The drain of the MOSFET V35 is connected to resistors R24 and R23, respectively. The other end of resistor R23 is connected to resistor R22, pin 1 of comparator U3, and capacitor C60, respectively. The other end of resistor R22 is connected to the power supply terminal. Pin 2 of comparator U3 is connected to the second filter circuit and the signal isolation module, respectively. Pin 3 of comparator U3 is connected to the power supply terminal. Pin 5 of comparator U3 is connected to resistor R25. The other end of resistor R25 is connected to the power-down signal output terminal. Pin 4 of comparator U3, the source of MOSFET V35, resistors R26 and R24, and the other end of capacitor C60 are grounded.

[0014] In one preferred embodiment, the second filter circuit includes a capacitor C65; one end of the capacitor C65 is connected to pin 2 of the comparator U3, and the other end of the capacitor C65 is grounded.

[0015] In the above technical solution of this utility model, the power failure detection circuit for a power distribution automation terminal includes: a lightning surge protection module, a threshold setting module, a signal isolation module, and a signal hysteresis module; the lightning surge protection module is connected to the power supply voltage input terminal, the lightning surge protection module is connected to the signal isolation module, the signal isolation module is connected to both the threshold setting module and the signal hysteresis module, and the threshold setting module is connected to the power supply voltage input terminal. This utility model solves the technical problems of how to set monitoring thresholds according to the characteristics of backup power supplies and how to avoid repeated oscillations in monitoring signals.

[0016] In this invention, a threshold setting module is used to set an accurate monitoring threshold based on the characteristics of the backup power supply. At the same time, the power-on and power-off hysteresis functions are added to avoid the problem of repeated oscillation of the monitoring signal when the monitoring voltage is near the threshold, thus effectively solving problems such as false alarms in remote signaling. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1This is a schematic diagram of a power failure detection circuit for a power distribution automation terminal according to an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the lightning surge protection module, threshold setting module, and signal isolation module according to an embodiment of the present utility model;

[0020] Figure 3 This is a schematic diagram of the signal hysteresis module according to an embodiment of the present invention.

[0021] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Furthermore, in this utility model, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0024] Furthermore, the technical solutions of the various embodiments of this utility model can be combined with each other, but only if they are based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0025] See Figures 1-3 According to one aspect of the present invention, the present invention provides a power failure detection circuit for a power distribution automation terminal, wherein the power failure detection circuit for the power distribution automation terminal includes:

[0026] Lightning surge protection module, threshold setting module, signal isolation module, and signal hysteresis module;

[0027] The input terminal of the lightning surge protection module is electrically connected to the positive terminal of the power supply voltage input, the output terminal of the lightning surge protection module is electrically connected to the input terminal of the signal isolation module, the output terminal of the signal isolation module is electrically connected to the input terminals of the threshold setting module and the signal hysteresis module respectively, and the output terminal of the threshold setting module is electrically connected to the negative terminal of the power supply voltage input.

[0028] Specifically, in this embodiment, the present invention is particularly suitable for power distribution automation terminals that use batteries or supercapacitors as backup power sources. Since the backup power source of the power distribution automation terminal is also the power source for the remote signaling and control circuit, when the backup power source voltage is insufficient, although the normal operation of the system can be maintained, when the backup power source voltage is too low, the remote signaling signal cannot be maintained, which will cause remote signaling misjudgment and false alarm. The present invention sets an accurate monitoring threshold according to the characteristics of the backup power source, and adds the function of power-on and power-off hysteresis to avoid the problem of repeated oscillation of the monitoring signal when the monitoring voltage is near the threshold, effectively solving the problem of remote signaling false alarm. Compared with the traditional method of using diode isolation and monitoring chip, the present invention monitors the high-voltage side without voltage drop and does not affect the power supply.

[0029] Specifically, in this embodiment, the lightning surge protection circuit includes a resistor R920 and a bidirectional Zener diode Z39. One end of the resistor R920 is connected to the positive terminal of the power supply voltage input, and the other end of the resistor R920 is connected to the signal isolation module and the bidirectional Zener diode Z39. The other end of the bidirectional Zener diode Z39 is connected to the negative terminal of the power supply voltage input and the signal isolation module. The resistor R920 needs to be a power resistor with a power rating of 1W or higher to withstand the energy released during a lightning surge. The bidirectional Zener diode Z39 is a TVS diode for subsequent protection, and its voltage level ensures that the subsequent circuit will not be affected by overvoltage.

[0030] Specifically, in this embodiment, the signal isolation module includes a first filtering circuit, a current limiting circuit, and a signal isolation circuit; the first filtering circuit is electrically connected to the lightning surge protection circuit, the current limiting circuit, and the threshold setting module, respectively; the current limiting circuit is electrically connected to the signal isolation circuit; and the signal isolation circuit is electrically connected to the threshold setting module and the signal hysteresis module, respectively.

[0031] Specifically, in this embodiment, the first filtering circuit includes capacitors C605 and C606; one end of capacitor C606 is connected to the lightning surge protection circuit, the current limiting circuit, and the threshold setting module, respectively; one end of capacitor C605 is connected to the current limiting circuit; and the other ends of capacitors C605 and C606 are grounded. The current limiting circuit includes resistors R918 and R919; one end of resistor R919 is connected to capacitor C606 and the threshold setting module, respectively; the other end of resistor R919 is connected to capacitor C605 and resistor R918, respectively; and the other end of resistor R918 is connected to the signal isolation circuit. By removing unwanted frequency components from the signal through the first filtering circuit, the signal quality is improved, ensuring a smoother output DC current.

[0032] Specifically, in this embodiment, the signal isolation circuit includes an optocoupler U53; pin 1 of the optocoupler U53 is connected to a current limiting circuit, pin 2 of the optocoupler U53 is connected to a threshold setting module, pin 3 of the optocoupler U53 is connected to resistors R921 and R922 and capacitor C607 respectively, the other end of resistor R921 is grounded, the other end of resistor R922 is connected to a signal hysteresis module, and the other end of capacitor C607 is connected to pin 4 of the optocoupler U53 and the power supply terminal respectively; isolation through the optocoupler U53 can effectively prevent interference from the power supply side from affecting the stable operation of the equipment system.

[0033] Specifically, in this embodiment, the threshold setting circuit includes resistors R7 and R16 and a voltage regulator V34; pin 1 of the voltage regulator V34 is connected to resistors R16 and R7 respectively, the other end of resistor R7 is connected to a current limiting circuit, the other end of resistor R16 is connected to the negative terminal of the power supply voltage input, pin 2 of the voltage regulator V34 is connected to a signal isolation circuit, and pin 3 of the voltage regulator V34 is connected to a first filter circuit; the voltage regulator V34 is a three-terminal adjustable voltage regulator, and the power-down threshold can be flexibly set by adjusting the resistance values ​​of resistors R7 and R16; when V24P Before the _IN voltage rises from 0 to the threshold value, the voltage regulator V34 remains in a high-impedance state. Once the voltage reaches the threshold value, the voltage regulator V34 begins to regulate the voltage, and the signal isolation circuit starts working, transmitting a power-on signal to the system side. The system then knows that the power supply is sufficient and that all circuits are reliable. When the V24P_IN voltage drops from the rated voltage, and when it drops to the threshold value set by the voltage regulator V34, the optocoupler U53 stops working. At this point, the system considers the power supply voltage insufficient, and the signals fed back from each circuit cannot be used as valid signals. The input and output ports are then locked to prevent malfunctions. The V24P_IN voltage is the input power supply voltage.

[0034] Specifically, in this embodiment, the signal hysteresis module includes a comparator U3, a MOSFET V35, resistors R26, R24, R23, and R22, a capacitor C60, a resistor R25, and a second filter circuit. The gate of the MOSFET V35 is connected to resistor R26 and the power-down signal output terminal, respectively. The drain of the MOSFET V35 is connected to resistors R24 and R23, respectively. The other end of resistor R23 is connected to resistor R22, pin 1 of comparator U3, and capacitor C60, respectively. The other end of resistor R22 is connected to the power supply terminal. Pin 2 of comparator U3 is connected to the second filter circuit and the signal isolation module, respectively. Pin 3 of comparator U3 is connected to the power supply terminal. Pin 5 of comparator U3 is connected to resistor R25. The other end of resistor R25 is connected to the power-down signal output terminal. Pin 4 of comparator U3, the source of MOSFET V35, resistors R26 and R24, and the other end of capacitor C60 are grounded.

[0035] Specifically, in this embodiment, the signal V_JC output by the signal isolation module is input to comparator U3. When the input voltage V24P_IN is lower than the threshold, V_JC is low. At this time, the power-down signal output by comparator U3 is also low. MOS transistor V35 is in the off state, and the negative input voltage of comparator U3 is the 3.3V system power supply voltage divided by resistors R22, R23, and R24. When the input voltage V24P_IN is higher than the threshold, V_JC is high. At this time, the power-down signal output by comparator U3 is also high. MOS transistor V35 is in the on state, and the negative input voltage of comparator U3 is the 3.3V system power supply voltage divided by R22 and R23. This voltage division is less than the previous voltage division, thus creating a hysteresis voltage after the power-down signal flips, preventing the power-down signal from repeatedly flipping when the input voltage is near the threshold, which could cause system misjudgment.

[0036] Specifically, in this embodiment, the second filtering circuit includes a capacitor C65; one end of the capacitor C65 is connected to pin 2 of the comparator U3, and the other end of the capacitor C65 is grounded; the second filtering circuit removes unwanted frequency components from the signal output by the signal isolation module, thereby improving signal quality and ensuring a smoother output signal.

[0037] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural transformations made based on the inventive concept of this utility model and the contents of this utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this utility model.

[0038] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural transformations made based on the inventive concept of this utility model and the contents of this utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this utility model.

Claims

1. A power failure detection circuit for a power distribution automation terminal, characterized in that, include: Lightning surge protection module, threshold setting module, signal isolation module, and signal hysteresis module; The lightning surge protection module is connected to the power supply voltage input terminal. The lightning surge protection module is connected to the signal isolation module. The signal isolation module is connected to the threshold setting module and the signal hysteresis module respectively. The threshold setting module is connected to the power supply voltage input terminal.

2. The power failure detection circuit for a power distribution automation terminal according to claim 1, characterized in that, The lightning surge protection module includes a resistor R920 and a bidirectional Zener diode Z39; one end of the resistor R920 is connected to the positive terminal of the power supply voltage input, and the other end of the resistor R920 is connected to the signal isolation module and the bidirectional Zener diode Z39 respectively. The other end of the bidirectional Zener diode Z39 is connected to the negative terminal of the power supply voltage input and the signal isolation module respectively.

3. A power failure detection circuit for a power distribution automation terminal according to any one of claims 1-2, characterized in that, The signal isolation module includes a first filtering circuit, a current limiting circuit, and a signal isolation circuit. The first filtering circuit is electrically connected to the lightning surge protection circuit, the current limiting circuit, and the threshold setting module, respectively. The current limiting circuit is electrically connected to the signal isolation circuit, and the signal isolation circuit is electrically connected to the threshold setting module and the signal hysteresis module, respectively.

4. The power failure detection circuit for a power distribution automation terminal according to claim 3, characterized in that, The first filter circuit includes capacitor C605 and capacitor C606; one end of capacitor C606 is connected to the lightning surge protection circuit, the current limiting circuit and the threshold setting module respectively, one end of capacitor C605 is connected to the current limiting circuit, and the other ends of capacitors C605 and C606 are grounded.

5. A power failure detection circuit for a power distribution automation terminal according to claim 4, characterized in that, The current limiting circuit includes resistors R918 and R919; one end of resistor R919 is connected to capacitor C606 and threshold setting module respectively, the other end of resistor R919 is connected to capacitor C605 and resistor R918 respectively, and the other end of resistor R918 is connected to signal isolation circuit.

6. A power failure detection circuit for a power distribution automation terminal according to claim 3, characterized in that, The signal isolation circuit includes an optocoupler U53; pin 1 of the optocoupler U53 is connected to a current limiting circuit, pin 2 of the optocoupler U53 is connected to a threshold setting module, pin 3 of the optocoupler U53 is connected to resistors R921 and R922 and capacitor C607 respectively, the other end of resistor R921 is grounded, the other end of resistor R922 is connected to a signal hysteresis module, and the other end of capacitor C607 is connected to pin 4 of the optocoupler U53 and the power supply terminal respectively.

7. A power failure detection circuit for a power distribution automation terminal according to claim 3, characterized in that, The threshold setting circuit includes resistors R7 and R16 and a voltage regulator V34; pin 1 of the voltage regulator V34 is connected to resistors R16 and R7 respectively, the other end of resistor R7 is connected to a current limiting circuit, the other end of resistor R16 is connected to the negative terminal of the power supply voltage input, pin 2 of the voltage regulator V34 is connected to a signal isolation circuit, and pin 3 of the voltage regulator V34 is connected to a first filter circuit.

8. A power failure detection circuit for a power distribution automation terminal according to any one of claims 1-2, characterized in that, The signal hysteresis module includes a comparator U3, a MOSFET V35, resistors R26, R24, R23, and R22, a capacitor C60, a resistor R25, and a second filter circuit. The gate of the MOSFET V35 is connected to resistor R26 and the power-down signal output terminal, respectively. The drain of the MOSFET V35 is connected to resistors R24 and R23, respectively. The other end of resistor R23 is connected to resistor R22, pin 1 of comparator U3, and capacitor C60, respectively. The other end of resistor R22 is connected to the power supply terminal. Pin 2 of comparator U3 is connected to the second filter circuit and the signal isolation module, respectively. Pin 3 of comparator U3 is connected to the power supply terminal. Pin 5 of comparator U3 is connected to resistor R25. The other end of resistor R25 is connected to the power-down signal output terminal. Pin 4 of comparator U3, the source of MOSFET V35, resistors R26 and R24, and the other end of capacitor C60 are grounded.

9. A power failure detection circuit for a power distribution automation terminal according to claim 8, characterized in that, The second filter circuit includes a capacitor C65; one end of the capacitor C65 is connected to pin 2 of the comparator U3, and the other end of the capacitor C65 is grounded.

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