Grid-connected monitoring device

Abstract

The present invention relates to a grid-connected monitoring device, including a shell, a power board, a core board and a bottom plate; the shell adopts a cylindrical structure with a rectangular cross section, a plurality of PCB guide grooves are arranged inside the shell, and the front and rear panels adopt an aluminum plate; the power board, the core board and the bottom plate are respectively installed inside the shell through the PCB guide grooves; the power board is electrically connected to the core board and the bottom plate respectively, and the core board and the bottom plate are electrically connected. The shell has good heat dissipation, strong anti-interference ability, good anti-seismic characteristics, can be fixedly installed, and can be installed on a guide rail, providing structural convenience for subsequent expansion modules; the core board integrates a CPU, Nand Flash, Nor Flash, SRAM and Ethernet physical layer chip, adds an independent filtering energy storage capacitor to ensure its stability; adds filtering and decoupling to filter out low-frequency and high-frequency interference or clutter.

Description

Technical Field

[0001] The invention relates to the technical field of electronic current, and in particular to a grid-connected monitoring device. Background Art

[0002] The existing grid-connected monitoring devices have the following defects in circuit structure: 1) They are susceptible to electromagnetic interference and have poor heat dissipation, resulting in a short equipment life; 2) The installation method is single and inconvenient for field application; 3) There is a lack of processing measures for special working conditions such as high temperature reduction and overvoltage shock, resulting in unstable power supply.

[0003] Therefore, it is necessary to improve and optimize the existing grid-connected monitoring devices. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a grid-connected monitoring device, the stability of which is greatly improved.

[0005] The technical solution adopted by the present invention to solve the above problems is: a grid-connected monitoring device, including a shell, characterized in that it also includes a power board, a core board and a bottom board; the shell adopts a cylindrical structure with a rectangular cross section, and a plurality of PCB guide grooves are arranged inside the shell, and the front and rear panels thereof adopt aluminum plates; the power board, the core board and the bottom board are respectively installed inside the shell through the PCB guide grooves; the power board is electrically connected to the core board and the bottom board respectively, and the core board and the bottom board are electrically connected;

[0006] The power board includes a common-mode filter circuit and a customized mutual inductor; the common-mode filter circuit includes a varistor R1, safety capacitors C1, C2, C3, C4, C5, C6, common-mode inductors JP1, JP2, inductors L1, L2 and a power module U8; common-mode inductors JP1 and JP2 each have two input terminals AC220N and AC220L, and two output terminals; the varistor R1 and the safety capacitor C2 are connected in parallel, the two ends of the varistor R1 are connected to AC220N and AC220L respectively, and the two ends of the safety capacitor C2 are connected to AC220N and AC220L respectively; one end of the safety capacitor C1 is connected to AC220L, and the other end of the safety capacitor C1 is connected to the ground; one end of the safety capacitor C3 is connected to AC220N, and the other end of the safety capacitor C3 is connected to the ground; the common-mode The output end of the inductor JP1 is connected to the input end of the common-mode inductor JP2, one output end of the common-mode inductor JP2 is connected to the input end of the inductor L1, the other output end of the common-mode inductor JP2 is connected to the input end of the inductor L2, and the output ends of the inductors L1 and L2 are connected to the power module U8; the safety capacitors C4, C5, and C6 are respectively connected to the input end of the common-mode inductor JP2 and the earth and the output end of the common-mode inductor JP1 as the second-level protection, and the specific connection relationship is: the two output ends of the common-mode inductor JP1 are respectively connected to the two input ends of the common-mode inductor JP2 through two wires, the two ends of the safety capacitor C5 are respectively connected to the two wires, one end of the safety capacitor C4 is connected to one wire, and the other end is connected to the earth, and one end of the safety capacitor C6 is connected to another wire, and the other end is connected to the earth;

[0007] The core board integrates a CPU circuit, a Flash circuit, an SRAM circuit, a first crystal oscillator circuit, a second crystal oscillator circuit and a filter energy storage capacitor; the CPU circuit is connected to the Flash circuit and the SRAM circuit through an FMSC bus; the first crystal oscillator circuit is the main oscillator of the CPU circuit; the second oscillator circuit is the clock oscillator of the CPU circuit; the filter energy storage circuit provides interference filtering and signal acquisition energy storage for CPU circuit signal acquisition;

[0008] The bottom plate includes a conditioning circuit, a power-off energy unit, a communication interface and an overvoltage protection circuit, wherein the conditioning circuit is connected to the CPU circuit on the core board to send the collected electrical signal to the CPU, which filters, amplifies and buffers the electrical signal, and converts the analog signal into a digital signal through an analog-to-digital converter; the power-off energy unit provides energy supply for the entire device within a certain period of time when power is off; the upper end of the communication interface and the overvoltage protection circuit is connected to the CPU circuit of the core board, and the lower end outlet is the communication interface;

[0009] The conditioning circuit includes resistors R17, R21, R30, R34, R38, R42, capacitors C43, C48, C53, C59, C8, and amplifiers U112A, U112B, and U101; the amplifier U112A has pin 1, pin 2, and pin 3, the U112B has pin 5, pin 6, and pin 7, and the U101 has pin 5, pin 6, and pin 7; one end of the resistor R17 is connected to the analog input signal in the CPU circuit integrated on the core board 2, and the other end of R17 is connected to one end of the resistor R21 and one end of the capacitor C43; the other end of the resistor R21 is connected to pin 3 of the amplifier U112A and one end of the capacitor C48; the other end of the capacitor C43 is connected to the amplifier Pin 1 of amplifier U112A; the other end of capacitor C48 is connected to the power ground; Pin 1 of amplifier U112A is connected to one end of resistor R30, and the other end of resistor R30 is connected to resistor R34 and capacitor C53; the other end of resistor R34 is connected to pin 5 of amplifier U112B and capacitor C59; the other end of C53 is connected to pin 7 of amplifier U112B; the other end of C59 is connected to the power ground; pin 7 of amplifier U112B is connected to one end of resistor R38; the other end of R38 is connected to resistor R42 and pin 5 of amplifier U101; the other end of R42 is connected to the level-raising output terminal; pin 7 of amplifier U1101 is connected to one end of capacitor C8; the other end of C8 is connected to the power ground;

[0010] The circuit of the power-off energy unit includes diodes D23 and D24, a resistor R48 and supercapacitors C55 and C58; the A end of the diode D24 is connected to the device power supply +5V, and the K end of the diode D24 is connected to the resistor R48; the other end of R48 is connected to the A end of the diode D23 and the positive ends of the capacitors C55 and C58; the K end of the diode D23 is connected to the bottom plate working power supply; the other ends of C55 and C58 are connected to the power ground;

[0011] The communication interface and overvoltage protection circuit include resistors R7 and R11, capacitors C26 and C27, resettable fuses F2 and F3, glass discharge tubes SP1, SP2 and SP3, anti-static device D7 and communication chip U9; one end of resistor R7 is connected to pin 4 of communication chip U9, and the other end of R7 is connected to a 3.3V power supply; one end of resistor R11 is connected to pin 3 of communication chip U9, and the other end is connected to a 3.3V power supply; capacitor C26 is connected to pin 1 and pin 8 of communication chip U9, pin 1 of communication chip U9 is connected to a 3.3V power supply, and pin 8 is grounded. Capacitor C27 is connected to pins 9 and 16 of the communication chip U9; the resettable fuse F2 is connected to pin 13 of U9, and the other end is connected to SP1, SP2 and pin 1 of D7; one end of the resettable fuse F3 is connected to pin 12 of U9, and the other end is connected to pin 2 of D7, one end of SP3 and the other end of SP2; the other end of SP1 is connected to the communication ground; the other end of SP3 is connected to the communication ground; pin 3 of D7 is connected to the communication ground.

[0012] Preferably, the housing is made of extruded aluminum.

[0013] Preferably, the first crystal oscillator circuit uses a 25 MHz crystal oscillator, and the second crystal oscillator circuit uses a 32.768 crystal oscillator.

[0014] Preferably, the baseboard also includes an open-input and open-output circuit, a status display circuit and an expansion support circuit.

[0015] Preferably, the communication interface includes an Ethernet interface, a serial port, and a CAN interface.

[0016] Preferably, the housing is installed in two ways: fixed installation or guide rail installation.

[0017] Compared with the prior art, the present invention has the following advantages and effects:

[0018] 1. The shell has the following advantages: good heat dissipation; strong anti-interference ability; good anti-seismic characteristics; can be fixedly installed or installed on a guide rail; provides structural convenience for subsequent expansion modules;

[0019] 2. The core board integrates CPU, Nand Flash, Nor Flash, SRAM and Ethernet physical layer chip, adds independent filtering energy storage capacitors to ensure its stability; adds filtering and decoupling to filter out low-frequency and high-frequency interference or clutter;

[0020] 3. The design of power supply and related external circuits fully considers the impact of special working conditions such as low-temperature startup, high-temperature capacity reduction, overvoltage shock, etc. to ensure the stability of system power supply; the common-mode filter circuit design effectively suppresses the impact of electromagnetic interference of the system, and also ensures the relative isolation of the internal power module from the external circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 It is a schematic structural diagram of an embodiment of the present invention.

[0023] Figure 2 is a circuit diagram of a common-mode filtering circuit according to an embodiment of the present invention.

[0024] Figure 3 is a circuit diagram of a conditioning circuit according to an embodiment of the present invention.

[0025] Figure 4 FIG. 4 is a circuit diagram of a power-off energy unit according to an embodiment of the present invention.

[0026] Figure 5 is a circuit diagram of a communication interface and an overvoltage protection circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0028] Example

[0029] See also Figures 1 to 5 .

[0030] The present embodiment discloses a grid-connected monitoring device, including a housing 4, a power board 1, a core board 2 and a bottom board 3. The housing 4 adopts a cylindrical structure with a rectangular cross section, and is made of extruded aluminum. A plurality of PCB guide grooves are arranged inside the housing, and the front and rear panels are made of aluminum plates. The housing 4 adopts two installation methods: fixed installation or guide rail installation. The housing 4 has the following advantages: good heat dissipation; strong anti-interference ability; good anti-seismic characteristics; can be fixedly installed or guide rail installed; and provides structural convenience for subsequent expansion modules.

[0031] In this embodiment, the power board 1, the core board 2 and the bottom board 3 are respectively installed inside the housing 4 through PCB guide grooves; the power board 1 is electrically connected to the core board 2 and the bottom board 3, and the core board 2 and the bottom board 3 are electrically connected.

[0032] In this embodiment, the power board 1 includes a common-mode filter circuit and a customized transformer, and the customized transformer is divided into a current transformer and a voltage transformer.

[0033] Reference Figure 2The common-mode filter circuit includes a varistor R1, safety capacitors C1, C2, C3, C4, C5, C6, common-mode inductors JP1, JP2, inductors L1, L2 and a power module U8. Common-mode inductors JP1 and JP2 each have two input terminals AC220N and AC220L, and two output terminals; the varistor R1 and the safety capacitor C2 are connected in parallel, the two ends of the varistor R1 are connected to AC220N and AC220L respectively, and the two ends of the safety capacitor C2 are connected to AC220N and AC220L respectively; one end of the safety capacitor C1 is connected to AC220L, and the other end of the safety capacitor C1 is connected to the ground; one end of the safety capacitor C3 is connected to AC220N, and the other end of the safety capacitor C3 is connected to the ground; the output end of the common-mode inductor JP1 is connected to the input end of the common-mode inductor JP2, one output end of the common-mode inductor JP2 is connected to the input end of the inductor L1, and the other output end of the common-mode inductor JP2 is connected to the input end of the inductor L2, and the output ends of the inductors L1 and L2 are both connected to the power module U8.

[0034] Safety capacitors C4, C5, and C6 are used as the second-level protection and are respectively connected between the input end of the common-mode inductor JP2 and the ground and the output end of the common-mode inductor JP1. The specific connection relationship is: the two output ends of the common-mode inductor JP1 are respectively connected to the two input ends of the common-mode inductor JP2 through two wires, the two ends of the safety capacitor C5 are respectively connected to the two wires, one end of the safety capacitor C4 is connected to one wire, and the other end is connected to the ground, and one end of the safety capacitor C6 is connected to another wire, and the other end is connected to the ground.

[0035] The design of the power module and related external circuits fully considers the impact of special operating conditions such as low-temperature startup, high-temperature derating, and overvoltage shock, to ensure the stability of the system power supply; the common-mode filter circuit design effectively suppresses the impact of electromagnetic interference in the system, while also ensuring the relative isolation of the internal power module from the external circuit.

[0036] To ensure signal isolation, the system electrical parameters do not use direct resistance sampling, but a customized mutual inductor solution used in relay protection. This solution effectively eliminates the impact of external signal disturbances or faults on the internal system.

[0037] The core board 2 integrates the CPU circuit, the Flash circuit, the SRAM circuit, the first crystal oscillator circuit, the second crystal oscillator circuit and the filter energy storage capacitor. The first crystal oscillator circuit uses a 25MHz crystal oscillator, and the second crystal oscillator circuit uses a 32.768 crystal oscillator. The CPU circuit connects the Flash circuit and the SRAM circuit through the FMSC bus; the first crystal oscillator circuit is the main oscillator of the CPU circuit; the second oscillator circuit is the clock oscillator of the CPU circuit; the filter energy storage circuit provides interference filtering and signal acquisition energy storage for the CPU circuit signal acquisition.

[0038] Core board 2 mainly integrates CPU, Nand Flash, Nor Flash, SRAM and Ethernet physical layer chip, as follows:

[0039] 1) Industrial-grade 4-layer PCB immersion gold design, stronger anti-interference;

[0040] 2) 1GB Nand Flash, FSMC bus access;

[0041] 3) 16MB Nor Flash, FSMC bus access;

[0042] 4) 4MB SRAM, FSMC bus access;

[0043] 5) Low power and high performance Ethernet PHY chip, accessed using RMII interface;

[0044] 6) Add a 25MHz crystal oscillator circuit to provide a timing reference for reliable operation of the system;

[0045] 7) Add a 32.768KHz crystal oscillator circuit to drive the independent watchdog and drive the RTC real-time clock through program selection;

[0046] 8) Add independent filtering energy storage capacitors to ensure its stability;

[0047] 9) Increase filtering and decoupling to filter out low-frequency and high-frequency interference or clutter.

[0048] The bottom plate 3 includes a conditioning circuit, a power-off energy unit, a communication interface and an overvoltage protection circuit, an open-in and open-out circuit, a status display circuit and an expansion support circuit, wherein the conditioning circuit is connected to the CPU circuit on the core board 2 to send the collected electrical signal to the CPU, which filters, amplifies and buffers the electrical signal, and converts the analog signal into a digital signal through an analog-to-digital converter. The communication interface includes an Ethernet interface, a serial port, and a CAN interface. The power-off energy unit provides energy supply for the entire device within a certain period of time when power is off; the upper end of the communication interface and the overvoltage protection circuit is connected to the CPU circuit of the core board 2, and the lower end outlet is the communication interface.

[0049] See also Figure 3 The conditioning circuit includes resistors R17, R21, R30, R34, R38, R42, capacitors C43, C48, C53, C59, C8, and amplifiers U112A, U112B, and U101; amplifier U112A has pins 1, 2, and 3, U112B has pins 5, 6, and 7, and U101 has pins 5, 6, and 7.

[0050] One end of resistor R17 is connected to the analog input signal of the CPU circuit integrated on the core board 2, and the other end of R17 is connected to one end of resistor R21 and one end of capacitor C43; the other end of resistor R21 is connected to pin 3 of amplifier U112A and one end of capacitor C48; the other end of capacitor C43 is connected to pin 1 of amplifier U112A; the other end of capacitor C48 is connected to the power ground; pin 1 of amplifier U112A is connected to one end of resistor R30, and the other end of resistor R30 is connected to resistor R34 and capacitor C53; the other end of resistor R34 is connected to pin 5 of amplifier U112B and capacitor C59; the other end of C53 is connected to pin 7 of amplifier U112B; the other end of C59 is connected to the power ground; pin 7 of amplifier U112B is connected to one end of resistor R38; the other end of R38 is connected to resistor R42 and pin 5 of amplifier U101; the other end of R42 is connected to the level-raising output terminal; pin 7 of amplifier U1101 is connected to one end of capacitor C8; the other end of C8 is connected to the power ground.

[0051] See also Figure 4 The circuit of the power-off energy unit includes diodes D23 and D24, a resistor R48 and supercapacitors C55 and C58; the A end of the diode D24 is connected to the device power supply +5V, and the K end of the diode D24 is connected to the resistor R48; the other end of R48 is connected to the A end of the diode D23 and the positive ends of the capacitors C55 and C58; the K end of the diode D23 is connected to the bottom plate working power supply; the other ends of C55 and C58 are connected to the power ground.

[0052] See also Figure 5 The communication interface and overvoltage protection circuit include resistors R7 and R11, capacitors C26 and C27, self-recovery fuses F2 and F3, glass discharge tubes SP1, SP2 and SP3, anti-static device D7, and communication chip U9. One end of resistor R7 is connected to pin 4 of communication chip U9, and the other end of R7 is connected to 3.3V power supply; one end of resistor R11 is connected to pin 3 of communication chip U9, and the other end is connected to 3.3V power supply; capacitor C26 is connected to pin 1 and pin 8 of communication chip U9, pin 1 of communication chip U9 is connected to 3.3V power supply, and pin 8 is grounded. Capacitor C27 is connected to pins 9 and 16 of the communication chip U9; the resettable fuse F2 is connected to pin 13 of U9, and the other end is connected to SP1, SP2 and pin 1 of D7; one end of the resettable fuse F3 is connected to pin 12 of U9, and the other end is connected to pin 2 of D7, one end of SP3 and the other end of SP2; the other end of SP1 is connected to the communication ground; the other end of SP3 is connected to the communication ground; pin 3 of D7 is connected to the communication ground.

[0053] 1) After the signal conditioning part is designed, according to the system design parameters, the collected electrical parameters are filtered, amplified, buffered, and analog signaled before being sent to the CPU, and finally converted into digital signals through ADC for data processing of the system;

[0054] 2) In order to ensure that the data acquisition device records and stores the fault process in the event of a power grid failure, the system designs a power-off energy unit circuit to ensure the normal operation of the data acquisition device within the product planning time;

[0055] 3) Communication interface design includes physical interface and connection design of Ethernet, conventional serial port and CAN interface to ensure the physical stability of communication;

[0056] 4) The open-input and open-output loop design provides the system with the minimum digital input and output interface required to facilitate external control and feedback of the system working status;

[0057] 5) Considering the special requirements of wind farm environmental adaptability, an overvoltage protection circuit is added to the interface circuit to suppress external surges through the overvoltage protection characteristics of the TVS tube;

[0058] 6) The status indication circuit indicates according to different state machines, which is convenient for on-site data extraction and fault troubleshooting;

[0059] 7) The expansion design makes functional preparations for future module parallel connection, function expansion and access.

[0060] The index parameters of this grid-connected monitoring device are shown in Table 1.

[0061] Table 1

[0062]

[0063]

[0064] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is only an example of the structure of the present invention. All equivalent changes or simple changes made based on the structure, features and principles of the patent concept of the present invention are included in the protection scope of the patent of the present invention. Technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A grid-connected monitoring device, comprising a housing (4), characterized in that: It also includes a power board (1), a core board (2) and a bottom board (3); the housing (4) adopts a cylindrical structure with a rectangular cross section, a plurality of PCB guide grooves are arranged inside the housing (4), and the front and rear panels are made of aluminum plates; the power board (1), the core board (2) and the bottom board (3) are respectively installed inside the housing (4) through the PCB guide grooves; the power board (1) is electrically connected to the core board (2) and the bottom board (3), and the core board (2) is electrically connected to the bottom board (3); the power board (1) includes a common mode filter circuit and a customized Transformer; the common-mode filtering circuit includes a varistor R1, safety capacitors C1, C2, C3, C4, C5, C6, common-mode inductors JP1, JP2, inductors L1, L2 and a power module U8; common-mode inductors JP1 and JP2 each have two input terminals AC220N and AC220L, and two output terminals; the varistor R1 and the safety capacitor C2 are connected in parallel, the two ends of the varistor R1 are connected to AC220N and AC220L respectively, and the two ends of the safety capacitor C2 are connected to AC220N and AC220L respectively. C220L is connected; one end of the safety capacitor C1 is connected to AC220L, and the other end of the safety capacitor C1 is connected to the ground; one end of the safety capacitor C3 is connected to AC220N, and the other end of the safety capacitor C3 is connected to the ground; the output end of the common mode inductor JP1 is connected to the input end of the common mode inductor JP2, one output end of the common mode inductor JP2 is connected to the input end of the inductor L1, and the other output end of the common mode inductor JP2 is connected to the input end of the inductor L2, and the output ends of the inductors L1 and L2 are both connected to the power module U8; Safety capacitors C4, C5, and C6 are used as the second-level protection and are respectively connected between the input end of the common-mode inductor JP2 and the earth and the output end of the common-mode inductor JP1. The specific connection relationship is: the two output ends of the common-mode inductor JP1 are respectively connected to the two input ends of the common-mode inductor JP2 through two wires, the two ends of the safety capacitor C5 are respectively connected to the two wires, one end of the safety capacitor C4 is connected to one wire, and the other end is connected to the earth, and one end of the safety capacitor C6 is connected to another wire, and the other end is connected to the earth; The core board (2) integrates a CPU circuit, a Flash circuit, an SRAM circuit, a first crystal oscillator circuit, a second crystal oscillator circuit and a filter energy storage capacitor; the CPU circuit is connected to the Flash circuit and the SRAM circuit via an FMSC bus; the first crystal oscillator circuit is the main oscillator of the CPU circuit; the second oscillator circuit is the clock oscillator of the CPU circuit; the filter energy storage circuit provides interference filtering and signal acquisition energy storage for CPU circuit signal acquisition; The bottom plate (3) comprises a conditioning circuit, a power-off energy unit, a communication interface and an overvoltage protection circuit, wherein the conditioning circuit is connected to the CPU circuit on the core board (2) to send the collected electrical signal to the CPU, which filters, amplifies and buffers the electrical signal and converts the analog signal into a digital signal through an analog-to-digital converter; the power-off energy unit provides energy supply for the entire device for a certain period of time when power is off; the upper ends of the communication interface and the overvoltage protection circuit are connected to the CPU circuit of the core board (2), and the lower ends are outlets for the communication interface; The conditioning circuit includes resistors R17, R21, R30, R34, R38, R42, capacitors C43, C48, C53, C59, C8, and amplifiers U112A, U112B, and U101; the amplifier U112A has pin 1, pin 2, and pin 3, the U112B has pin 5, pin 6, and pin 7, and the U101 has pin 5, pin 6, and pin 7; one end of the resistor R17 is connected to the analog input signal in the CPU circuit integrated on the core board 2, and the other end of R17 is connected to one end of the resistor R21 and one end of the capacitor C43; the other end of the resistor R21 is connected to pin 3 of the amplifier U112A and one end of the capacitor C48; the other end of the capacitor C43 is connected to the amplifier Pin 1 of amplifier U112A; the other end of capacitor C48 is connected to the power ground; Pin 1 of amplifier U112A is connected to one end of resistor R30, and the other end of resistor R30 is connected to resistor R34 and capacitor C53; the other end of resistor R34 is connected to pin 5 of amplifier U112B and capacitor C59; the other end of C53 is connected to pin 7 of amplifier U112B; the other end of C59 is connected to the power ground; pin 7 of amplifier U112B is connected to one end of resistor R38; the other end of R38 is connected to resistor R42 and pin 5 of amplifier U101; the other end of R42 is connected to the level-raising output terminal; pin 7 of amplifier U1101 is connected to one end of capacitor C8; the other end of C8 is connected to the power ground; The circuit of the power-off energy unit includes diodes D23 and D24, a resistor R48 and supercapacitors C55 and C58; the A end of the diode D24 is connected to the device power supply +5V, and the K end of the diode D24 is connected to the resistor R48; the other end of R48 is connected to the A end of the diode D23 and the positive ends of the capacitors C55 and C58; the K end of the diode D23 is connected to the bottom plate working power supply; the other ends of C55 and C58 are connected to the power ground; The communication interface and overvoltage protection circuit include resistors R7, R11, capacitors C26, C27, self-resetting fuses F2, F3, glass discharge tubes SP1, SP2, SP3, anti-static device D7, and communication chip U9; one end of resistor R7 is connected to pin 4 of communication chip U9, and the other end of R7 is connected to a 3.3V power supply; one end of resistor R11 is connected to pin 3 of communication chip U9, and the other end is connected to a 3.3V power supply; capacitor C26 is connected to pins 1 and 8 of communication chip U9. , Pin 1 of the communication chip U9 is connected to the 3.3V power supply, and pin 8 is connected to the ground; capacitor C27 is connected to pins 9 and 16 of the communication chip U9; the resettable fuse F2 is connected to pin 13 of U9, and the other end is connected to SP1, SP2 and pin 1 of D7; one end of the resettable fuse F3 is connected to pin 12 of U9, and the other end is connected to pin 2 of D7, one end of SP3 and the other end of SP2; the other end of SP1 is connected to the communication ground; the other end of SP3 is connected to the communication ground; pin 3 of D7 is connected to the communication ground; The base plate (3) also includes an open-in and open-out circuit, a status display circuit and an expansion support circuit; The housing (4) is installed in two ways: fixed installation or guide rail installation.

2. The grid-connected monitoring device according to claim 1, characterized in that: The housing (4) is made of extruded aluminum.

3. The grid-connected monitoring device according to claim 1, characterized in that: The first crystal oscillator circuit uses a 25MHz crystal oscillator, and the second crystal oscillator circuit uses a 32.768KHz crystal oscillator.

4. The grid-connected monitoring device according to claim 1, characterized in that: The communication interface includes an Ethernet interface, a serial port, and a CAN interface.

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