CN113394878A

CN113394878A - Low-voltage power grid physical topology automatic identification generating circuit

Info

Publication number: CN113394878A
Application number: CN202110454487.0A
Authority: CN
Inventors: 卢昌树; 景红; 郭小广; 史海舰; 张增辉
Original assignee: Beijing Zhongzhao Loongson Software Technology Co ltd
Current assignee: Beijing Zhongzhao Loongson Software Technology Co ltd
Priority date: 2021-04-26
Filing date: 2021-04-26
Publication date: 2021-09-14

Abstract

The invention discloses a physical topology automatic identification generating circuit of a low-voltage power grid, wherein a topology identification characteristic current enabling control circuit is connected with a lightning surge suppression circuit; the lightning surge suppression circuit is connected with the characteristic current generation part self-power-taking circuit, the topology identification characteristic current generation circuit and the voltage out-of-limit monitoring protection circuit; the characteristic current generation part is connected with the topology identification characteristic current trigger control circuit and the voltage out-of-limit monitoring protection circuit from the power taking circuit; the voltage out-of-limit monitoring protection circuit is connected with the topology identification characteristic current generation circuit. The physical topology automatic identification generating circuit for the low-voltage power grid has the advantages of extremely high safety, strong anti-interference performance, high circuit flexibility, high identification success rate, small circuit equipment volume and the like, can realize the rapid detection of whether the circuit breaker is an Internet of things circuit breaker, and is used for solving the problems of low safety, large volume, poor flexibility, low identification success power, long identification time and the like of the existing product.

Description

Low-voltage power grid physical topology automatic identification generating circuit

Technical Field

The invention relates to the technical field of intelligent low-voltage power grids, in particular to a low-voltage power grid physical topology automatic identification generating circuit.

Background

The method comprises the steps of realizing high-frequency data acquisition, automatic station area identification, phase topology identification, active reporting of power failure events, station area phase-splitting power failure analysis, accurate clock management, communication network monitoring and optimization, ID unified identification management, station area line loss theoretical interval analysis, phase-splitting line loss analysis, station area power quality monitoring, station area stealing violation intelligent analysis and diagnosis, distributed photovoltaic monitoring, online operation automation, station area electrical topology identification, station area load monitoring, station area branch line power failure analysis, station area meter box power failure analysis, branch line loss analysis, meter box line loss analysis, distribution and transformation environment monitoring, accurate station area fault sensing, power utilization safety hazard identification, station area personnel mobility analysis, station area user behavior characteristic analysis, accurate load sensing, energy value-added service for customers, station area line impedance analysis, meter box opening and closing lean management, Distributed photovoltaic absorption, orderly charging of electric vehicles, accurate load prediction, intelligent energy consumption response of residents and families and energy consumption optimization control functions of transformer areas;

in the application of an intelligent power grid, the application of low-voltage electric automatic topology recognition is the basis for supporting other applications, and the existing characteristic current generation methods are roughly divided into two types: the first type is that a thyristor is used as a switch, a resistor is used as a load, the thyristor and the resistor are connected in series, two ends of the thyristor and the resistor are respectively connected with an N line and a phase line, and voltage (U) is applied to two ends of the resistor (R) to generate current (I), wherein the I is U/R. The scheme has lower cost and simple principle; the second type is a mode of controlling the periodic conduction of a switching tube after full-wave rectification, and periodically generating a small load current in a power grid.

Based on the principles of the two existing characteristic current schemes, in the first category, due to the characteristic that the positive anode of the thyristor is conducted and the negative anode of the thyristor is closed, namely, the control signal of the thyristor can only turn on the thyristor, and the thyristor can be closed only after the alternating voltage is reversed when the thyristor is closed, so that the characteristic current generation has uncontrollable continuity, is easily influenced by the load characteristic of a power grid, has low safety, and has large required power of a resistor, so that the resistor has large volume and is not beneficial to being embedded into an equipment terminal; in the second category, a switch tube is used for controlling the switch of a resistance load after rectification, and as the switch tube needs to be conducted for a long time, the resistance value is required to be large when the resistor is selected, the current is small, and the overall heating is small; therefore, the amplitude of the output characteristic current is small, and the output characteristic current is easily interfered by field load fluctuation, voltage fluctuation and harmonic current, so that the problems of low success rate and long identification time of the characteristic current identification are caused.

The two schemes do not consider the problems of power grid voltage fluctuation, harmonic interference, lightning surge impact and equipment failure in a passive automatic topology characteristic current identification mode, and if the voltage fluctuates or the deviation of a starting point is close to the peak point of the voltage, the current is increased; if the field disturbance is too large or a lightning surge occurs, the switching tube is conducted when the characteristic current is not started, other elements are damaged, and overcurrent faults can be caused to damage the equipment. Meanwhile, if harmonic interference of the power grid is serious, the recognition success rate is low or the recognition is impossible.

Disclosure of Invention

The invention aims to provide a low-voltage power grid physical topology automatic identification generating circuit which can realize quick detection of whether a breaker is an Internet of things breaker and is used for solving the problems of low safety, large volume, poor flexibility, low identification success power, long identification time and the like of the existing product.

In order to achieve the purpose, the invention provides the following technical scheme:

a physical topology automatic identification generating circuit of a low-voltage power grid comprises a topology identification characteristic current enabling control circuit, a lightning surge suppression circuit, a characteristic current generating part self-power-taking circuit, a topology identification characteristic current trigger control circuit, a topology identification characteristic current generating circuit and a voltage out-of-limit monitoring protection circuit;

the topology identification characteristic current enabling control circuit is connected with the lightning surge suppression circuit; the lightning surge suppression circuit is connected with the characteristic current generation part self-power-taking circuit, the topology identification characteristic current generation circuit and the voltage out-of-limit monitoring protection circuit; the characteristic current generation part is connected with the topology identification characteristic current trigger control circuit and the voltage out-of-limit monitoring protection circuit from the power taking circuit; the voltage out-of-limit monitoring protection circuit is connected with the topology identification characteristic current generation circuit.

Furthermore, the topology identification characteristic current ENABLE control circuit comprises current limiting resistors R16 and R17, filter capacitors C9 and C8, a driving tube Q3, a current limiting resistor R15, a reverse diode D4, an isolation control switch K1 and an ENABLE control signal TP _ ENABLE; one end of the current limiting resistor R16 is connected with an enable control IO port of the single chip microcomputer, and the other end of the current limiting resistor R16 is connected with a base electrode of the driving tube Q3; the power supply VCC is connected with an input coil of the isolation control switch, the other end of the coil of the isolation control switch is connected to a collector of the driving tube Q3 after passing through a current-limiting resistor R15, and an emitter of the driving tube Q3 is connected to a power ground; the output of the isolation control switch is connected with a live wire L, the live wire is controlled to be connected into the module, and the whole module is powered on.

Furthermore, the lightning surge suppression circuit comprises an inductor L1, a diode D1, a diode D2 and a piezoresistor VR 1; one end of the inductor L1 is sequentially connected with an alternating current power supply and the cathode of the diode D2, and the other end of the inductor L1 is sequentially connected with the anode of the diode D2 and one end of the piezoresistor VR 1; the other end of the voltage dependent resistor VR1 is connected with a grounding wire; and the diode D1 can rapidly bleed the directional voltage of the inductor L1.

Furthermore, the characteristic current generation part self-fetching circuit comprises a current limiting resistor R14, a transient diode TVS4, a voltage stabilizing diode Z3, an electrolytic capacitor EC1 and a capacitor C7; wherein, the voltage-regulator diode Z3 is a 12V voltage-regulator tube; one end of the current-limiting resistor R14 is sequentially connected with the cathode of the voltage-stabilizing diode Z3 and one ends of the electrolytic capacitor EC1 and the capacitor C7; the anode of the voltage-stabilizing diode Z3 and the other electrode plates of the electrolytic capacitor EC1 and the capacitor C7 are connected with the ground wire; one pin of the transient diode TVS4 is connected between the current limiting resistor R14, and the other pin is connected with the ground wire; the alternating current power supply forms a direct current power supply VEE through half-wave rectification of a diode D2, and the voltage of the direct current power supply VEE is stabilized by a voltage stabilizing diode Z3, stored and filtered by an electrolytic capacitor EC1, and the voltage of the output stabilized power supply VEE is 12V after being filtered by a capacitor C7.

Furthermore, the topology identification characteristic current TRIGGER control circuit comprises a driving optocoupler UC1, a triode Q1, a resistor R3, a resistor R2, a resistor R4, a capacitor C3 and a TRIGGER control signal TP _ TRIGGER; pin 1 and pin 3 of the driving optocoupler UC1 are respectively connected with a power supply VCC and one end of a resistor R2, pin 5 is connected with a cathode of a diode D10 and one end of a resistor R5, and pin 6 is connected with a module power supply voltage VEE; the other end of the resistor R2 is connected with the collector of the triode Q1; one end of each resistor R3 is connected with a control signal TP _ TRIGGER, and the other end of each resistor R3 is connected with the base electrode and the grounding wire of the triode Q1 respectively; the emitter of transistor Q1 is connected to ground.

Furthermore, the topology identification characteristic current generation circuit comprises a thermistor PTC1, a switching tube Q2, a capacitor C5, a transient diode TVS2, a resistor R9, a resistor R5 and a diode D10; one end of the thermistor PTC1 is connected to the diode D2, the other end is connected to the drain of the switch tube Q2, and the switch tube Q2 is a power electronic switch tube; a pin of the transient diode TVS2 is connected to the gate of the switching transistor Q2 and one end of the resistor R9; the other end of the resistor R9, the other pin of the transient diode TVS2, the source of the switching tube Q2, and one polar plate of the capacitor C3 and the capacitor C4 are all connected with the ground wire; the other polar plate of the capacitor C3 is connected with a power supply voltage VCC; the other polar plate of the capacitor C4 is connected between the drain of the switch tube Q2 and the thermistor PTC 1; the anode and the cathode of the diode D10 are connected to both ends of the resistor R5, respectively, and the anode of the diode D10 is connected between the resistor R7 and the resistor R5.

Further, the calculation formula of the characteristic current I occurring when the resistance value of the thermistor PTC1 is RPTC is: i is VD 1/RPTC; wherein, VD1 is the positive half cycle AC power instantaneous value shaped by diode D2.

Furthermore, the voltage out-of-limit monitoring protection circuit comprises a voltage detector UC5, a transient diode TVS3, a capacitor C4, a resistor R11, a resistor R10, a resistor R6, a resistor R8, and a resistor R7; one end of a resistor R10 at the other end of the resistor R11, one end of a capacitor C4, one end of a transient diode TVS3 and 2 pins of a voltage detector UC5 are all connected; pin 1 of the voltage detector UC5 is connected between resistors R6 and R8, and pin 3 thereof is connected to a ground line; the other ends of the resistor R6 and the resistor R8 are respectively connected with a power supply voltage VCC and a ground wire; the resistor R11 and the resistor R13 are connected in sequence; one end of the resistor R11 is respectively connected with the thermistor PTC 1; one polar plate of the capacitor C4 is connected to one pin of the transient diode TVS3, and is connected between the resistor R10 and the resistor R11, and the other polar plate of the capacitor C4 and the other pin of the transient diode TVS3 are both connected to the ground line.

Furthermore, the calculation formula of the input voltage VDD of pin 1 of the voltage detector UC5 is as follows:

VDD＝VD1*R10/(R11+R10)；

the point difference between the input voltage VDD at pin 1 of the voltage detector UC5 and the dc power VD1 is trimmed by the capacitor C4.

Compared with the prior art, the invention has the beneficial effects that:

1. the physical topology automatic identification generating circuit of the low-voltage power grid is extremely high in safety, and the switching relay is adopted for electrical isolation, so that the conditions of equipment damage and short circuit caused by most power grid interference are avoided; an overvoltage detection circuit and an overcurrent protection circuit are adopted, so that the conditions of overlarge conduction current and component damage of equipment are avoided; the possible faults of the power grid can be effectively avoided.

2. The physical topology automatic identification generating circuit of the low-voltage power grid is strong in anti-interference, surge impact is effectively inhibited by combining the inductor and the piezoresistor, an overvoltage monitoring system is designed for overvoltage protection, triggering characteristic current can be coded, the circuit and the circuit can be effectively protected, and the characteristic current at the moment of interference is prevented from being covered.

3. The physical topology automatic identification generating circuit of the low-voltage power grid is high in circuit flexibility, a high-voltage power electronic switching tube is used as a switching device, the withstand voltage can reach over 1200V, the switching speed is high, the circuit can be effectively promoted to be rapidly powered on and powered off under the condition of high-current conduction, the existing circuit is prevented from having a delay effect, heating of elements is reduced, and compared with other schemes, the current can be designed to be larger under the same volume.

4. The automatic identification generating circuit for the physical topology of the low-voltage power grid, provided by the invention, has the advantages of high identification success rate, adjustable amplitude of the trigger characteristic current and adjustable trigger time, and can be used for randomly coding the characteristic current so as to provide the automatic topology identification success rate.

5. The automatic identification generating circuit for the physical topology of the low-voltage power grid, provided by the invention, has the advantages of small volume of circuit equipment, short switch conduction time, small heat generation in an equipment period, small element packaging size and capability of being better embedded into an equipment terminal.

Drawings

FIG. 1 is a block diagram of the circuit of the present invention;

FIG. 2 is a schematic diagram of the circuit of the present invention;

FIG. 3 is a circuit diagram of the topology identification feature current enable control of the present invention;

FIG. 4 is a lightning surge suppression circuit diagram of the present invention;

FIG. 5 is a self-powered circuit diagram of a characteristic current generating portion of the present invention;

FIG. 6 is a circuit diagram of the topology identification feature current trigger control of the present invention;

FIG. 7 is a circuit diagram of a topology identification feature current generation of the present invention;

FIG. 8 is a diagram of a voltage out-of-limit monitoring protection circuit according to the present invention.

In the figure: 1. a topology identification feature current enable control circuit; 2. a lightning surge suppression circuit; 3. the characteristic current generation part is a self-fetching circuit; 4. the topology identification characteristic current triggers the control circuit; 5. a topology identification characteristic current generation circuit; 6. the voltage monitoring protection circuit that transfinites.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-2, in the embodiment of the present invention: the automatic identification generating circuit for the physical topology of the low-voltage power grid comprises a topology identification characteristic current enabling control circuit 1, a lightning surge suppression circuit 2, a characteristic current generation part self-power-taking circuit 3, a topology identification characteristic current trigger control circuit 4, a topology identification characteristic current generating circuit 5 and a voltage out-of-limit monitoring protection circuit 6.

The topology identification characteristic current enabling control circuit 1 is connected with the lightning surge suppression circuit 2; the lightning surge suppression circuit 2 is connected with the characteristic current generation part self-powered circuit 3, the topology identification characteristic current generation circuit 5 and the voltage out-of-limit monitoring protection circuit 6; the characteristic current generation part is connected with the power taking circuit 3, the topology identification characteristic current trigger control circuit 4 and the voltage out-of-limit monitoring protection circuit 6; the voltage out-of-limit monitoring protection circuit 6 is connected with the topology identification characteristic current generation circuit 5.

In the above embodiment, the topology identification characteristic current enable control circuit 1 can control the ac voltage of the whole functional module, and the functional module is not needed to be used most of the time, so the electrical connection of the live wire L is disconnected on the physical connection, and the live wire L is enabled only when the automatic topology function is needed, and the software selects the relevant stable time period of the power grid to enable the live wire L to be connected, thereby ensuring the safety of the device; the lightning surge suppression circuit 2 can slow down and absorb surge voltage generated by thunder in the circuit or equipment connection or disconnection under the condition that the topology identification characteristic current enable control circuit 1 is enabled, so that the impact on a generating module is reduced; the characteristic current generation part self-powered circuit 3 can convert alternating current into direct current, and the direct current is output into stable power supply voltage VEE through voltage stabilization and filtering; the topology identification characteristic current trigger control circuit 4 can drive the topology identification characteristic current generation circuit 5 to generate characteristic current through an optical coupler; the voltage out-of-limit monitoring protection circuit 6 can monitor the characteristic current and the voltage in the topology identification characteristic current generation circuit 5, and can perform safety protection on the access equipment of the topology identification characteristic current generation circuit 5.

Referring to fig. 3, the topology identification feature current ENABLE control circuit 1 includes current limiting resistors R16 and R17, filter capacitors C9 and C8, a driving transistor Q3, a current limiting resistor R15, a reverse diode D4, an isolation control switch K1, and an ENABLE control signal TP _ ENABLE; one end of the current limiting resistor R16 is connected with an enable control IO port of the single chip microcomputer, and the other end of the current limiting resistor R16 is connected with a base electrode of the driving tube Q3; the power supply VCC is connected with an input coil of the isolation control switch, the other end of the coil of the isolation control switch is connected to a collector of the driving tube Q3 after passing through a current-limiting resistor R15, and an emitter of the driving tube Q3 is connected to a power ground; the output of the isolation control switch is connected with a live wire L, the live wire is controlled to be connected into the module, and the whole module is powered on.

Referring to fig. 4, the lightning surge suppression circuit 2 includes an inductor L1, a diode D1, a diode D2, and a varistor VR 1; one end of the inductor L1 is sequentially connected with an alternating current power supply and the cathode of the diode D2, and the other end of the inductor L1 is sequentially connected with the anode of the diode D2 and one end of the piezoresistor VR 1; the other end of the voltage dependent resistor VR1 is connected with a grounding wire; and the diode D1 can rapidly bleed the directional voltage of the inductor L1.

Referring to fig. 5, the characteristic current generating part self-extracting circuit 3 includes a current limiting resistor R14, a transient diode TVS4, a zener diode Z3, an electrolytic capacitor EC1, and a capacitor C7; wherein, the voltage-regulator diode Z3 is a 12V voltage-regulator tube; one end of the current-limiting resistor R14 is sequentially connected with the cathode of the voltage-stabilizing diode Z3 and one ends of the electrolytic capacitor EC1 and the capacitor C7; the anode of the voltage-stabilizing diode Z3 and the other electrode plates of the electrolytic capacitor EC1 and the capacitor C7 are connected with the ground wire; one pin of the transient diode TVS4 is connected between the current limiting resistor R14, and the other pin is connected with the ground wire; the alternating current power supply forms a direct current power supply VEE through half-wave rectification of a diode D2, and the voltage of the direct current power supply VEE is stabilized by a voltage stabilizing diode Z3, stored and filtered by an electrolytic capacitor EC1, and the voltage of the output stabilized power supply VEE is 12V after being filtered by a capacitor C7.

Referring to fig. 6, the topology identification characteristic current TRIGGER control circuit 4 includes a driving optocoupler UC1, a transistor Q1, a resistor R3, a resistor R2, a resistor R4, a capacitor C3, and a TRIGGER control signal TP _ TRIGGER; pin 1 and pin 3 of the driving optocoupler UC1 are respectively connected with a power supply VCC and one end of a resistor R2, pin 5 is connected with a cathode of a diode D10 and one end of a resistor R5, and pin 6 is connected with a module power supply voltage VEE; the other end of the resistor R2 is connected with the collector of the triode Q1; one end of each resistor R3 is connected with a control signal TP _ TRIGGER, and the other end of each resistor R3 is connected with the base electrode and the grounding wire of the triode Q1 respectively; the emitter of transistor Q1 is connected to ground.

Referring to fig. 7, the topology identification characteristic current generation circuit 5 includes a thermistor PTC1, a switching tube Q2, a capacitor C5, a transient diode TVS2, a resistor R9, a resistor R5, and a diode D10; one end of the thermistor PTC1 is connected to the diode D2, the other end of the thermistor PTC1 is connected to the drain electrode of the switch tube Q2, and the switch tube Q2 is a power electronic switch tube and has the characteristics of high voltage resistance and small on-off time delay; a pin of the transient diode TVS2 is connected to the gate of the switching transistor Q2 and one end of the resistor R9; the other end of the resistor R9, the other pin of the transient diode TVS2, the source of the switching tube Q2, and one polar plate of the capacitor C3 and the capacitor C4 are all connected with the ground wire; the other polar plate of the capacitor C3 is connected with a power supply voltage VCC; the other polar plate of the capacitor C4 is connected between the drain of the switch tube Q2 and the thermistor PTC 1; the anode and the cathode of the diode D10 are connected to both ends of the resistor R5, respectively, and the anode of the diode D10 is connected between the resistor R7 and the resistor R5.

When the resistance value of the thermistor PTC1 is RPTC, the formula for calculating the generated characteristic current I is: i is VD 1/RPTC; wherein, VD1 is the positive half cycle AC power instantaneous value shaped by diode D2.

In the above embodiment, the topology identification characteristic current generation circuit 5 uses a relay as the on-off of the electrical and physical connection; the high-voltage power electronic switch tube Q2 is used as a characteristic current start-stop switch, the thermistor PTC1 is used as a resistance load to directly generate characteristic current, and a control signal is conducted through a relay, so that the whole circuit is connected with a live wire L power supply to allow triggering and generating the characteristic current; then the optical coupler is isolated through a trigger signal; the alternating current commercial power line adopts the combination of an inductor and a piezoresistor to effectively suppress surge impact, and a voltage monitoring system is designed to carry out overcurrent protection, so that the safety of the whole power grid of the power electronic switching tube can be effectively protected; the power electronic switch tube is used as a switch device, the voltage resistance is high, the switching speed is high, the power failure delay phenomenon does not exist, the thermistor PTC1 is small as a load, the load is convenient to embed into an equipment terminal, when overcurrent occurs, the thermistor PTC1 has certain action delay characteristics, at the moment, the thermistor PTC1 can be used as a pure resistor, when fault current continues, the thermistor acts to cut off the current, and the power electronic switch tube can be protected, and meanwhile, the short-circuit fault of a power grid can also be avoided.

Referring to fig. 8, the voltage out-of-limit monitoring protection circuit 6 includes a voltage detector UC5, a transient diode TVS3, a capacitor C4, a resistor R11, a resistor R10, a resistor R6, a resistor R8, and a resistor R7; one end of a resistor R10 at the other end of the resistor R11, one end of a capacitor C4, one end of a transient diode TVS3 and 2 pins of a voltage detector UC5 are all connected; pin 1 of the voltage detector UC5 is connected between resistors R6 and R8, and pin 3 thereof is connected to a ground line; the other ends of the resistor R6 and the resistor R8 are respectively connected with a power supply voltage VCC and a ground wire; the resistor R11 and the resistor R13 are connected in sequence; one end of the resistor R11 is respectively connected with the thermistor PTC 1; one polar plate of the capacitor C4 is connected to one pin of the transient diode TVS3, and is connected between the resistor R10 and the resistor R11, and the other polar plate of the capacitor C4 and the other pin of the transient diode TVS3 are both connected to the ground line.

The calculation formula of the input voltage VDD of pin 1 of the voltage detector UC5 is as follows:

VDD＝VD1*R10/(R11+R10)；

In summary, the following steps: according to the low-voltage power grid physical topology automatic identification generating circuit, the isolation relay is adopted for electrical isolation, and the circuit safety is extremely high; a high-voltage power electronic switch tube is used as a characteristic current generating switch, a thermistor is used as a load to generate characteristic current, and a control signal is isolated by an optical coupler; the alternating current commercial power circuit adopts the combination of an inductor and a piezoresistor to effectively inhibit surge impact, and an overvoltage monitoring system is designed to carry out overcurrent protection, so that the safety of the whole power grid of a power electronic switching tube can be effectively protected; the system has the advantages of overvoltage and overcurrent protection monitoring and control, high safety and capability of effectively avoiding power grid faults; the power electronic switching tube is used as a switch, so that the circuit has high flexibility; moreover, the software coding, the current filtering identification and the anti-interference are extremely high, the identification success rate can reach 100 percent, and meanwhile, the circuit equipment is small in size and can be well embedded into an equipment terminal.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.

Claims

1. A physical topology automatic identification generating circuit of a low-voltage power grid is characterized by comprising a topology identification characteristic current enabling control circuit (1), a lightning surge suppression circuit (2), a characteristic current generating part self-fetching circuit (3), a topology identification characteristic current trigger control circuit (4), a topology identification characteristic current generating circuit (5) and a voltage out-of-limit monitoring protection circuit (6);

the topology identification characteristic current enabling control circuit (1) is connected with the lightning surge suppression circuit (2); the lightning surge suppression circuit (2) is connected with the characteristic current generation part self-fetching circuit (3), the topology recognition characteristic current generation circuit (5) and the voltage out-of-limit monitoring protection circuit (6); the characteristic current generation part self-taking circuit (3) is connected with the topology identification characteristic current trigger control circuit (4) and the voltage out-of-limit monitoring protection circuit (6); and the voltage out-of-limit monitoring protection circuit (6) is connected with the topology identification characteristic current generation circuit (5).

2. The automatic identification generation circuit for the physical topology of the low-voltage power grid as claimed in claim 1, characterized in that: the topology identification characteristic current ENABLE control circuit (1) comprises current limiting resistors R16 and R17, filter capacitors C9 and C8, a driving tube Q3, a current limiting resistor R15, a backward diode D4, an isolation control switch K1 and an ENABLE control signal TP _ ENABLE; one end of the current limiting resistor R16 is connected with an enable control IO port of the single chip microcomputer, and the other end of the current limiting resistor R16 is connected with a base electrode of the driving tube Q3; the power supply VCC is connected with an input coil of the isolation control switch, the other end of the coil of the isolation control switch is connected to a collector of the driving tube Q3 after passing through a current-limiting resistor R15, and an emitter of the driving tube Q3 is connected to a power ground; the output of the isolation control switch is connected with a live wire L, the live wire is controlled to be connected into the module, and the whole module is powered on.

3. The automatic identification generation circuit for the physical topology of the low-voltage power grid as claimed in claim 2, characterized in that: the lightning surge suppression circuit (2) comprises an inductor L1, a diode D1, a diode D2 and a piezoresistor VR 1; one end of the inductor L1 is sequentially connected with an alternating current power supply and the cathode of the diode D2, and the other end of the inductor L1 is sequentially connected with the anode of the diode D2 and one end of the piezoresistor VR 1; the other end of the voltage dependent resistor VR1 is connected with a grounding wire; and the diode D1 can rapidly bleed the directional voltage of the inductor L1.

4. The automatic identification generation circuit for the physical topology of the low-voltage power grid as claimed in claim 3, characterized in that: the characteristic current generation part self-fetching circuit (3) comprises a current limiting resistor R14, a transient diode TVS4, a voltage stabilizing diode Z3, an electrolytic capacitor EC1 and a capacitor C7; wherein, the voltage-regulator diode Z3 is a 12V voltage-regulator tube; one end of the current-limiting resistor R14 is sequentially connected with the cathode of the voltage-stabilizing diode Z3 and one ends of the electrolytic capacitor EC1 and the capacitor C7; the anode of the voltage-stabilizing diode Z3 and the other electrode plates of the electrolytic capacitor EC1 and the capacitor C7 are connected with the ground wire; one pin of the transient diode TVS4 is connected between the current limiting resistor R14, and the other pin is connected with the ground wire; the alternating current power supply forms a direct current power supply VEE through half-wave rectification of a diode D2, and the voltage of the direct current power supply VEE is stabilized by a voltage stabilizing diode Z3, stored and filtered by an electrolytic capacitor EC1, and the voltage of the output stabilized power supply VEE is 12V after being filtered by a capacitor C7.

5. The automatic identification generation circuit for the physical topology of the low-voltage power grid according to claim 4, wherein the topology identification characteristic current TRIGGER control circuit (4) comprises a drive optocoupler UC1, a triode Q1, a resistor R3, a resistor R2, a resistor R4, a capacitor C3 and a TRIGGER control signal TP _ TRIGGER; pin 1 and pin 3 of the driving optocoupler UC1 are respectively connected with a power supply VCC and one end of a resistor R2, pin 5 is connected with a cathode of a diode D10 and one end of a resistor R5, and pin 6 is connected with a module power supply voltage VEE; the other end of the resistor R2 is connected with the collector of the triode Q1; one end of each resistor R3 is connected with a control signal TP _ TRIGGER, and the other end of each resistor R3 is connected with the base electrode and the grounding wire of the triode Q1 respectively; the emitter of transistor Q1 is connected to ground.

6. The automatic identification generation circuit for the physical topology of the low-voltage power grid according to claim 5, characterized in that the topology identification characteristic current generation circuit (5) comprises a thermistor PTC1, a switch tube Q2, a capacitor C5, a transient diode TVS2, a resistor R9, a resistor R5 and a diode D10; one end of the thermistor PTC1 is connected to the diode D2, the other end is connected to the drain of the switch tube Q2, and the switch tube Q2 is a power electronic switch tube; a pin of the transient diode TVS2 is connected to the gate of the switching transistor Q2 and one end of the resistor R9; the other end of the resistor R9, the other pin of the transient diode TVS2, the source of the switching tube Q2, and one polar plate of the capacitor C3 and the capacitor C4 are all connected with the ground wire; the other polar plate of the capacitor C3 is connected with a power supply voltage VCC; the other polar plate of the capacitor C4 is connected between the drain of the switch tube Q2 and the thermistor PTC 1; the anode and the cathode of the diode D10 are connected to both ends of the resistor R5, respectively, and the anode of the diode D10 is connected between the resistor R7 and the resistor R5.

7. The automatic identification generation circuit for the physical topology of the low-voltage power grid as claimed in claim 6, wherein when the resistance value of the thermistor PTC1 is RPTC, the calculation formula of the generated characteristic current I is as follows: i is VD 1/RPTC; wherein, VD1 is the positive half cycle AC power instantaneous value shaped by diode D2.

8. The automatic identification and generation circuit for the physical topology of the low-voltage power grid according to claim 7, characterized in that the voltage out-of-limit monitoring and protection circuit (6) comprises a voltage detector UC5, a transient diode TVS3, a capacitor C4, a resistor R11, a resistor R10, a resistor R6, a resistor R8, a resistor R7; one end of a resistor R10 at the other end of the resistor R11, one end of a capacitor C4, one end of a transient diode TVS3 and 2 pins of a voltage detector UC5 are all connected; pin 1 of the voltage detector UC5 is connected between resistors R6 and R8, and pin 3 thereof is connected to a ground line; the other ends of the resistor R6 and the resistor R8 are respectively connected with a power supply voltage VCC and a ground wire; the resistor R11 and the resistor R13 are connected in sequence; one end of the resistor R11 is respectively connected with the thermistor PTC 1; one polar plate of the capacitor C4 is connected to one pin of the transient diode TVS3, and is connected between the resistor R10 and the resistor R11, and the other polar plate of the capacitor C4 and the other pin of the transient diode TVS3 are both connected to the ground line.

9. The automatic identification generation circuit for the physical topology of the low-voltage power grid as claimed in claim 8, wherein the calculation formula of the input voltage VDD of the 1 pin of the voltage detector UC5 is as follows:

VDD＝VD1*R10/(R11+R10)；