Electricity-theft-preventing anti-interference electric energy metering box

Abstract

The application discloses an anti-theft anti-interference metering box, and relates to the technical field of metering boxes. The metering box comprises a box body, a controller and a conductive grid. A signal isolation circuit comprising a radio frequency receiving and transmitting branch and a direct current anti-disassembly branch is connected in parallel with a feeding end of the conductive grid. High and low frequency signal isolation is realized through a radio frequency choke. A mechanical closed loop composed of a non-metallic mechanical stress wire and a spring energy storage micro switch is integrated in the box body. The application maintains an anti-disassembly monitoring state by monitoring the change of an antenna standing wave ratio in a radio frequency signal emission period. When the metering box is damaged by external force, an electronic latch branch is turned on, a standby battery is connected to supply power to the controller, and sampling data before and after an abnormal trigger is extracted and saved. Meanwhile, the fracture of the mechanical stress wire causes the physical contact of the micro switch to be closed, thereby establishing a standby power supply circuit between the standby battery and an alarm module, and ensuring the transmission of an alarm signal under the condition of main power supply failure and line damage.

Description

Technical Field

[0001] This invention relates to the field of metering box technology, and in particular to an anti-theft and anti-interference power metering box. Background Technology

[0002] As the core terminal for electricity settlement, the metering box's operational safety and data reliability are directly related to the economic interests and operational order of the power grid. To prevent intentional electricity theft and external damage, conventional metering box protection mechanisms usually involve installing anti-tamper mesh on the inner wall of the box.

[0003] With the increasing complexity of industrial power environments and the continuous improvement of electricity theft methods, basic protection solutions are no longer sufficient to meet on-site needs. In order to improve the space utilization rate inside the enclosure and increase the protected area, existing technologies attempt to reuse the anti-tamper mesh on the inner wall of the enclosure as a radio frequency communication antenna, so that the same physical mesh can be used for both DC anti-tamper monitoring and magnetic field coupling communication with external terminals. In order to deal with criminals who use strong magnets to interfere with internal components to complete electricity theft, existing metering boxes are equipped with corresponding magnetic sensitive components to monitor the external space magnetic field.

[0004] In the aforementioned prior art, when the metering box is violently damaged and electricity is stolen, the anti-tamper mesh is reused as an antenna, and the high-frequency radio frequency signal and the low-frequency DC detection signal share the same physical conductor. The high-energy alternating electromagnetic waves emitted by the radio frequency will generate electromagnetic interference to the DC detection circuit. The signal generated by the interference is difficult to distinguish from the signal generated by the actual violent damage, which makes it easy for the metering box to misjudge the electricity theft signal due to interference.

[0005] When the meter box is subjected to electricity theft due to electromagnetic interference, the magnetic sensitive components cannot distinguish the source of interference because there are often transient surge pulses in the industrial power grid and leakage magnetic fields of large electrical equipment. They may easily misjudge normal transient surge currents in the power grid as electricity theft. If the alarm threshold is forcibly increased, it is very easy to lose response when a constant strong magnetic field is applied to crack the alarm.

[0006] Therefore, it is necessary to invent an anti-theft and anti-interference power metering box to solve the above problems. Summary of the Invention

[0007] The purpose of this invention is to provide an anti-theft and anti-interference power metering box, which aims to solve the problems of power supply failure, insufficient anti-interference, and lack of solidified evidence when the metering box is exposed to strong magnetic interference, physical damage, or disconnection from the main power supply.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: an anti-theft and anti-interference power metering box, comprising a box body, a controller, and a conductive grid disposed within the box body; The conductive mesh is provided with a feed end and a return end, and the return end is connected to the information transmission circuit of the metering box; The power supply terminal is connected to a signal isolation circuit, which includes an RF transceiver branch and a DC anti-tamper branch connected in parallel to the power supply terminal. The radio frequency transceiver branch is connected to the radio frequency front end of the metering box and is used to send radio frequency signals to the conductive grid; The DC tamper protection branch is connected to the detection pin of the controller and is used to apply a DC detection voltage to the conductive mesh to form an tamper protection monitoring circuit. The DC tamper protection branch has high impedance in the operating frequency band to block the transmission of radio frequency signals to the controller.

[0009] Preferably, a DC blocking capacitor is connected in series in the radio frequency transceiver branch to isolate DC signals; A radio frequency choke is connected in series in the DC anti-tamper branch to maintain high impedance in the operating frequency band. An antenna tuning network is provided between the radio frequency transceiver branch and the controller, and the network includes an adjustable capacitor bank. The controller is configured to control the radio frequency front end to issue a sweep pulse before transmitting the radio frequency signal, and switch the access capacity of the adjustable capacitor bank according to the magnitude of the reflected power, so as to adjust the resonant frequency of the conductive grid.

[0010] Preferably, the controller is configured with an RF transmission shielding mode and a dynamic impedance monitoring mode; RF Transmit Shielding Mode: During the period when the RF transceiver branch transmits the RF signal, the controller shields the interrupt response from the DC tamper protection branch to prevent RF level fluctuations from causing false tamper protection triggers. Dynamic impedance monitoring mode: During the period when the radio frequency transceiver branch transmits radio frequency signals, the controller periodically acquires the standing wave ratio (SWR) parameter of the conductive mesh; and when the rate of change of the SWR parameter is lower than the set drift threshold, the dynamic reference value is updated; when the difference between the current SWR parameter and the dynamic reference value is greater than the anti-tamper judgment threshold within a preset time window and the difference remains unrecoverable, it is determined that the conductive mesh has physically broken, and an anti-tamper trigger signal is output.

[0011] Preferably, the back of the conductive mesh is composited with a non-metallic mechanical stress wire, one end of which is fixed to the inner wall of the box, and the other end is tensioned and connected to a spring-loaded micro switch. The metering box is also equipped with a backup power supply circuit, a backup battery, and an alarm module that are independent of the main power supply circuit. The spring energy storage micro switch and the alarm module are connected in series in the backup power supply circuit. Under normal conditions, the mechanical stress wire is under tension and overcomes the elastic force of the spring energy storage micro switch, keeping its contacts open. When the mechanical stress wire breaks, the spring energy storage micro switch loses its tension constraint and uses the internal spring potential energy to close the contacts, thereby connecting the backup battery and the alarm module.

[0012] Preferably, the backup power supply circuit also integrates an electronic latching branch, which is connected in parallel with the spring energy storage micro switch; the electronic latching branch includes a P-channel MOSFET and a pull-down resistor; the gate of the P-channel MOSFET is connected to a high level through the DC tamper protection branch to maintain a cut-off state, and the pull-down resistor is connected between the gate and ground; when the conductive mesh physically breaks or the main power supply circuit is de-energized, the DC tamper protection branch is opened or de-energized, the gate is pulled down to the conduction threshold through the pull-down resistor, and the P-channel MOSFET is turned on to trigger the backup battery to supply power to the controller.

[0013] Preferably, the system further includes multiple magnetic field sensors distributed at different locations within the housing; the controller is communicatively connected to each of the magnetic field sensors and is used to perform the following steps: Obtain the magnetic field strength output by the magnetic field sensor and calculate the rate of change of the magnetic field strength; If the rate of change is greater than the set rate of change threshold and falls back to the normal reference range within a preset time, it is determined to be a transient power grid interference and the current magnetic field data is ignored. If the real-time magnetic field strength is greater than the set static amplitude threshold, or the time-domain rate of change is greater than the rate of change threshold and does not fall back within the preset time, then the magnetic field gradient between each magnetic field sensor is calculated; when the magnetic field gradient is greater than the set gradient threshold, an abnormal signal is output.

[0014] Preferably, when the number of magnetic field sensors that output full-scale saturation signals exceeds a set threshold, the controller stops calculating the magnetic field gradient and directly outputs the abnormal signal.

[0015] Preferably, it further includes an adaptive power management module, which includes a backup battery and a battery discharge activation circuit electrically connected to the backup battery; The controller is configured to: acquire the resting time parameter and ambient temperature parameter of the backup battery; and calculate the battery resting time parameter based on the resting time parameter and the ambient temperature parameter. When the main power supply circuit is determined to be normal and the battery resting time parameter reaches the preset passivation threshold, the controller controls the battery discharge activation circuit to be turned on; wherein, the controller controls the battery discharge activation circuit by outputting a pulse width modulation signal with a step-increasing duty cycle, so as to perform pulse depassivation discharge on the backup battery.

[0016] Preferably, the controller has a circular buffer allocated within it and is communicatively connected to a non-volatile memory; the controller is configured as follows: Under normal monitoring conditions, the sampled data is cyclically overwritten into the circular buffer in a first-in-first-out manner, and the hash value of the current data in the circular buffer is periodically extracted and uploaded. When the abnormal signal or the tamper-proof trigger signal is obtained, the controller freezes the current write address of the ring buffer, extracts the sampled data before and after the trigger moment as a data storage data packet, and writes the data storage data packet into the non-volatile memory.

[0017] Preferably, when the metering box is damaged, causing the conductive mesh and the mechanical stress wire to break, the micro switch closes, connecting the power supply circuit from the backup battery to the alarm module, thus waking up the alarm module. Simultaneously, the controller utilizes the backup power provided by the electronic latch branch to perform a write operation of the evidence data packet to the non-volatile memory. After the write operation is completed, the controller transmits the evidence data packet to the alarm module, which is already in operation, through the communication bus between itself and the alarm module. The alarm module then broadcasts an alarm signal carrying the device identifier and the evidence data packet.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention, through the setting of a signal isolation circuit, utilizes the high and low frequency impedance characteristics of components to block the leakage of high-frequency radio frequency energy to the DC detection circuit, thus avoiding electromagnetic interference and false alarms during tampering. During the period when the controller shields the DC interruption to transmit radio frequency signals, by monitoring the dynamic standing wave ratio, the change in standing wave ratio caused by the change in antenna structure and impedance mismatch after the conductive mesh is broken, the anti-theft function is ensured when the DC detection is interrupted.

[0019] This invention uses a combination of time change rate and spatial magnetic field distribution gradient to identify electricity theft. By monitoring the time change rate of the magnetic field, it filters out interference from high-frequency transient surges in the power grid. By monitoring the spatial magnetic field gradient between multiple points, it distinguishes between uniform magnetic leakage of large equipment and attacks from strong magnetic objects that are placed close by people. This improves the accuracy of the metering box's state perception and anti-interference capability in complex power grid environments. Attached Figure Description

[0020] Figure 1 This is a block diagram of the overall hardware architecture of the present invention.

[0021] Figure 2 This is a schematic diagram of the layout of the conductive mesh and mechanical stress wires inside the metering box of the present invention.

[0022] Figure 3 The flowchart shows the logic for the controller of this invention to perform dynamic standing wave ratio monitoring and anti-tamper judgment.

[0023] Figure 4This is a flowchart of the spatial magnetic field identification and abnormal interruption logic of the present invention.

[0024] Figure label: 1. Housing; 2. Conductive mesh; 3. Mechanical stress tension wire; 4. Micro switch; 5. Guide positioning pin. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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. Example

[0026] This embodiment provides an anti-theft and anti-interference power metering box, such as... Figures 1 to 4 As shown, it is mainly deployed in special transformer metering scenarios. Its system hardware architecture mainly includes a controller, conductive grid 2, magnetic field sensor group, adaptive power management module and related signal processing and isolation network.

[0027] In this embodiment, the inner wall of the metering box 1 is attached with a conductive mesh 2, which serves as a common medium for physical anti-tampering and signal transmission and reception. The conductive mesh 2 is formed by a flexible printed circuit board with polyimide substrate to form a continuous closed copper foil trace. In order to achieve signal isolation between the same physical mesh during the transmission of radio frequency signals and DC detection signals, a signal isolation circuit is connected in parallel at the power supply nodes at both ends of the conductive mesh 2. The signal isolation circuit includes two parallel branches: a radio frequency transmission and reception branch and a DC anti-tampering branch.

[0028] Conductive mesh 2 is fabricated using a double-layer flexible printed circuit process to create continuous serpentine traces, which are then attached to the inner wall of housing 1. Its electrical path is a closed loop connected in series. Conductive mesh 2 constitutes a near-field magnetically coupled loop antenna, configured for magnetically coupled data exchange with an external communication terminal. Distributed compensation capacitors are connected in series at the nodes where the serpentine traces of conductive mesh 2 are spaced, to compensate for the parasitic inductance of the traces and adjust the resonant bandwidth of the antenna.

[0029] A DC blocking capacitor is connected in series between the RF transceiver branch and the RF front end. The impedance of this capacitor at 13.56MHz allows the RF signal to be transmitted to the conductive grid 2 while providing open-circuit isolation for the DC signal. The RF front end includes an RF transceiver chip, an RF power amplifier, or an RF transceiver module.

[0030] One end of the DC anti-tamper branch is connected to the detection pin of the controller. A first RF choke and a second RF choke are connected in series in its circuit. The first end of the first RF choke is connected to the feed terminal of the conductive grid 2. The second end of the first RF choke and the first end of the second RF choke are connected to the first node. The second end of the second RF choke is connected to the detection pin of the controller. A bypass capacitor is connected between the first node and the system reference ground. The bypass capacitor and the RF choke together form a low-pass filter network.

[0031] The first and second RF chokes utilize ferrite inductors with a self-resonant frequency greater than 30MHz, and their nominal inductance values ​​are set between 4.7μH and 22μH. The bypass capacitors have capacitance values ​​between 100pF and 1000pF. With this configuration, the low-pass filter network exhibits an insertion loss greater than 40dB for the 13.56MHz RF signal, limiting the transmission of RF energy towards the controller and providing a conductive path for the DC detection signal.

[0032] An automatic antenna tuning network is further integrated between the RF transceiver branch and the controller. The automatic antenna tuning network adopts a Π-type network structure. A fixed power inductor is connected in series between its input and output terminals, and an adjustable capacitor array is connected across the input and output terminals to the system reference ground. The adjustable capacitor array is specifically configured as a binary weighted capacitor array consisting of several fixed capacitors with different nominal capacitance values ​​connected in series with a high-frequency, low-on-resistance RF MOS switch.

[0033] Before transmitting radio frequency signals, the controller collects the reflected power of conductive grid 2 through a directional coupler and calculates the current voltage standing wave ratio (VSWR). When the VSWR deviates from the ideal range due to external interference or changes in the enclosure door, the controller dynamically switches the on / off combinations of each RF MOS switch in the binary weighted capacitor array through digital GPIO pins according to the built-in impedance search algorithm, thereby adjusting the equivalent capacitance of the matching circuit in stages. Through the adaptive impedance transformation of this Π-type matching network, the conductive grid 2 can still maintain resonance at the operating frequency of 13.56MHz when subjected to external environmental parasitic parameter disturbances.

[0034] The automatic antenna tuning network is specifically configured as follows: a fixed power inductor is connected in series between the network's input and output terminals; the network's input terminal is grounded through a first adjustable capacitor array, and the network's output terminal is grounded through a second adjustable capacitor array. A directional coupler is also cascaded between the RF transceiver branch and the input terminal of the automatic antenna tuning network. The coupled output terminal of this directional coupler is connected to the controller's ADC sampling pin to acquire reflected power and calculate the voltage standing wave ratio (VSWR).

[0035] The controller's built-in impedance search algorithm employs a successive approximation adjustment logic based on a binary weighted capacitor array. The specific adjustment process is as follows: Before RF transmission, the controller first closes the RF MOS switch corresponding to the most significant bit (MSB) of the binary weighted capacitor array and disconnects all other low bits, so that half of the total capacitance of the array is connected as the initial test state; then, the system obtains the current reflected power through the directional coupler and calculates the current voltage standing wave ratio parameter accordingly.

[0036] Based on this, the controller performs an approximation judgment to determine whether the current voltage standing wave ratio (VSWR) is less than the set target VSWR threshold. If it is less than the threshold, the controller controls the corresponding RF MOS switch to remain closed and continues to perform the same connection and test operation on the second highest bit. Conversely, if the current VSWR is greater than the set target VSWR threshold, the controller disconnects the RF MOS switch corresponding to that bit and then tests the second highest bit.

[0037] Following the above logic, the process proceeds sequentially to lower bits, iterating from the most significant bit (MSB) to the least significant bit (LSB) until all discrete switches in the array have been traversed. After the traversal process is completed, the final locked switch combination state is taken as the optimal equivalent capacitance value under the current environmental parameters.

[0038] The controller is equipped with time-division detection logic. During the window period when the RF transceiver branch is transmitting a signal, the controller shields the interrupt response of the DC anti-tamper branch to avoid level fluctuations caused by high-energy RF signals that could lead to false triggering of the anti-tamper logic. During the window period, the controller reuses the reflected power monitoring data of the automatic antenna tuning network. When the conductive mesh 2 is physically broken, causing a change in the electrical length of the antenna, the input impedance of the antenna undergoes a step change, resulting in an abnormal increase in reflected power. The controller calculates the current voltage standing wave ratio (VSWR) parameter, and when the difference between the VSWR parameter and the internally stored dynamic reference value exceeds the anti-tamper judgment threshold, it determines that the conductive mesh 2 has physically broken and immediately generates an anti-tamper trigger signal.

[0039] The controller is equipped with dynamic standing wave ratio (SWR) monitoring logic. Under normal monitoring conditions, the controller periodically acquires the SWR parameter of the conductive grid 2. When the rate of change of the SWR parameter is within the environmental drift threshold range, the controller updates the dynamic reference value in the memory using the current SWR parameter.

[0040] When conductive mesh 2 breaks, if the difference between the current VSWR parameter and the dynamic reference value exceeds the tamper detection threshold within the set sampling time window, the controller executes the interference status confirmation logic. The controller's tamper detection logic is configured in association with the status of the metering box access switch: if the access switch is in the opening process, the controller suspends the RF tamper detection and controls the antenna impedance rematch to establish a new dynamic reference value after the access switch is closed; if the access switch is in the closed state, and the difference in VSWR parameter exceeds the tamper detection threshold and remains unrecoverable, the controller generates an tamper detection trigger signal.

[0041] The magnetic field sensor group includes multiple magnetic field sensor units distributed in different positions inside the housing 1. The controller receives the real-time magnetic field strength data output by each magnetic field sensor unit and calculates its time-domain change rate ΔB / Δt. When the time-domain change rate fluctuates and falls back within a preset time window, the controller ignores the current magnetic field data. When the magnetic field strength exceeds the set static amplitude threshold, the controller calculates the spatial magnetic field distribution gradient ΔB / Δx between different magnetic field sensor units.

[0042] When the gradient of the spatial magnetic field distribution is greater than the preset dipole attenuation threshold, the controller determines that there is near-field magnetic field interference and outputs an abnormal signal. When the number of magnetic field sensor units that output full-scale saturation level exceeds the preset ratio, the controller stops executing the calculation steps for the spatial magnetic field distribution gradient and directly outputs an abnormal signal.

[0043] The calculation of the time-domain rate of change is based on the set discrete sampling period Δt. The controller obtains the magnetic field induction intensity in two adjacent sampling periods and calculates the current time-domain rate of change using the discrete difference formula.

[0044] The rate of change threshold is preset based on the nominal rising edge slope of the 50Hz / 60Hz power frequency inrush current of the power grid. When the calculated time-domain rate of change is greater than the threshold and falls back quickly, it indicates that this sudden change is a high-frequency transient power grid interference rather than a strong magnet that is placed continuously by humans. The controller will execute the filtering logic.

[0045] The calculation of the spatial magnetic field distribution gradient between each magnetic field sensor unit is as follows: The controller extracts the static magnetic field amplitudes B1 and B2 output by two adjacent magnetic field sensor units with a physical distance of d, and calculates the spatial gradient value; the preset gradient threshold is set based on the characteristic that the magnetic field of a strong magnet decays with distance; if a legally large external device leaks magnetic field, its magnetic field is already approximately a uniform magnetic field when it reaches the metering box, and the gradient value is small; while a strong magnet that is artificially placed close to the box 1 will cause a large local magnetic field drop; when the calculated spatial gradient value is greater than the preset gradient threshold, it is confirmed as close-range artificial magnetic field interference.

[0046] The adaptive power management module includes a backup battery and a battery discharge activation circuit electrically connected to it. The controller records the resting time parameter of the backup battery. When it is determined that the main power supply circuit is normal and the resting time parameter reaches the preset passivation threshold, the controller controls the battery discharge activation circuit to conduct. The controller outputs a pulse width modulation signal with a step-increasing duty cycle to control the battery discharge activation circuit, which sequentially performs current-limited pre-discharge and de-passivation discharge on the backup battery, and then disconnects the battery discharge activation circuit.

[0047] The controller is equipped with a circular buffer. Under normal conditions, the controller cyclically overwrites the sampled data into the circular buffer at a fixed sampling rate and extracts the hash value of the current data for output. After receiving an anti-tamper trigger signal or an abnormal signal, the controller freezes the overwrite pointer of the circular buffer. With the power support of the backup battery, it extracts the sampled data before and after the trigger moment as a data storage data packet and writes the data storage data packet into the non-volatile memory. Example

[0048] Based on the technical architecture of Embodiment 1, this embodiment further discloses a dual-path linkage triggering circuit for the anti-interference metering box under physical damage and main power supply failure conditions.

[0049] An armored radio frequency alarm module and a backup power supply circuit are installed inside the metering box in a position independent of the conductive grid 2. An insulated mechanical stress wire 3 is provided on the back or side of the conductive grid 2. In order to improve the monitoring coverage of physical anti-tampering, several guide positioning pins 5 are fixed interlaced on the inner wall of the box 1. The mechanical stress wire 3 is wound between each guide positioning pin 5, forming a cross layout with the conductive grid 2.

[0050] One end of the mechanical stress pull wire 3 is fixed to the inner wall of the housing 1, and the other end is connected to the spring energy storage micro switch 4. When the housing 1 is subjected to external drilling, cutting damage or large-area deformation, the mechanical stress pull wire 3 breaks and loses tension, causing the spring energy storage micro switch 4 to close. The mechanical stress pull wire 3 can be replaced with any insulating linkage with the characteristic of easy breakage under force, and the micro switch 4 can be replaced with other mechanical trigger switches.

[0051] The backup power supply circuit includes an electronic latch branch to provide a transient electrical conduction path. This electronic latch branch includes a P-channel MOSFET and a pull-down resistor. The source of the P-channel MOSFET is connected to the backup battery, and the drain is connected to the backup power supply pin of the armored RF alarm module and controller. The gate of the P-channel MOSFET is connected to the DC tamper protection branch. Under normal power supply conditions, the high-level signal of the DC tamper protection branch keeps the MOSFET in the off state. The pull-down resistor is connected between the gate and ground.

[0052] The DC anti-tamper branch forms a complete state-keeping loop. The main control system power supply is connected to one end of the conductive grid 2, such as the return end, through a current-limiting resistor. The other end of the conductive grid 2 is connected to the first node and passes through the RF choke to finally connect to the gate of the P-channel field-effect transistor.

[0053] When the conductive mesh 2 is in good working order, the DC high level of the main control system power supply is applied to the gate of the P-channel MOSFET through the closed trace of the conductive mesh 2 and the DC anti-tamper branch. This high level can overcome the pull-down effect of the pull-down resistor and keep the P-channel MOSFET in the off state.

[0054] When the metering box housing is damaged by drilling or cutting, causing the conductive mesh 2 to break, the DC path from the main control system power supply to the gate is cut off. At this time, the pull-down resistor quickly pulls the gate potential down to at least its conduction threshold, causing the P-channel field-effect transistor to immediately enter the saturation conduction state, forming the first backup power supply branch.

[0055] When the meter box housing is damaged by drilling or cutting, or the main power supply cable is cut, the conductive mesh 2 circuit is disconnected or the main power supply of the system is cut off. At this time, the DC anti-tamper branch is disconnected or loses voltage, and the gate of the P-channel MOSFET becomes low level, below its conduction threshold, so that the P-channel MOSFET is turned on, forming the first backup power supply branch. The backup battery supplies power to the controller and armored RF alarm module through this branch. The controller uses this power supply to complete the non-volatile storage operation of the buffer data.

[0056] Simultaneously, external force breaks the mechanical stress wire 3, and the disappearance of the tension causes the spring drive contact inside the spring energy storage micro switch 4 to close, forming a mechanical closed circuit. This directly connects the backup battery to the armored RF alarm module, directly waking it up and driving it into working condition. After the controller completes the non-volatile data writing using the transient power provided by the electronic latch branch, it transmits the evidence data packet to the awakened armored RF alarm module through an independent dedicated communication bus. The latter then sends an alarm signal to the outside, ensuring that the alarm signal can still be output normally even if a single electronic device fails or continuous physical damage occurs.

[0057] When the metering box experiences a drop in main power supply and is accompanied by physical damage, the internal circuit state changes as follows: An open circuit in conductive mesh 2 causes an electrical open circuit and voltage loss in the DC anti-tamper branch. The pull-down resistor pulls the gate potential of the P-channel MOSFET down to the conduction threshold, and the P-channel MOSFET immediately enters the saturation conduction state, forming the first backup power supply path. The controller uses this path to obtain transient power, executes the freeze command for the sampled data in the current ring buffer, and writes the evidence data packet to the non-volatile memory.

[0058] When physical breach occurs, the mechanical stress wire 3 breaks, resulting in loss of tension. The spring-loaded microswitch 4 loses its constraint and rebounds to close. The internal mechanical contacts connect the second power supply path between the backup battery and the armored radio frequency alarm module, enabling the alarm module to be woken up in seconds using pure hardware. At the same time, the controller uses the first backup power supply path to obtain transient power and writes the evidence data packet into the non-volatile memory. The system startup initialization of the alarm module requires a certain amount of time. After the controller completes the evidence data packet writing operation, it confirms that the armored radio frequency alarm module is ready through a delay waiting mechanism. Then, it transmits the evidence data packet to the armored radio frequency alarm module through the communication link. Finally, the alarm module broadcasts an alarm signal carrying evidence.

[0059] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A power metering box with anti-theft and anti-interference features, characterized in that, Includes a housing (1), a controller, and a conductive mesh (2) disposed inside the housing (1); The conductive mesh (2) is provided with a power supply end and a return end, and the return end is connected to the information transmission circuit of the metering box; The power supply terminal is connected to a signal isolation circuit, which includes an RF transceiver branch and a DC anti-tamper branch connected in parallel to the power supply terminal. The radio frequency transceiver branch is connected to the radio frequency front end of the metering box and is used to send radio frequency signals to the conductive grid (2). The DC anti-tamper branch is connected to the detection pin of the controller and is used to apply a DC detection voltage to the conductive mesh (2) to form an anti-tamper monitoring circuit; the DC anti-tamper branch has a high impedance in the working frequency band to block the radio frequency signal from entering the controller; A DC blocking capacitor is connected in series in the radio frequency transceiver branch to isolate DC signals; A radio frequency choke is connected in series in the DC anti-tamper branch to maintain high impedance in the operating frequency band. An antenna tuning network is provided between the radio frequency transceiver branch and the controller, and the network includes an adjustable capacitor bank. The controller is configured to control the radio frequency front end to issue a sweep pulse before transmitting the radio frequency signal, and switch the access capacity of the adjustable capacitor bank according to the magnitude of the reflected power, so as to adjust the resonant frequency of the conductive grid (2).

2. The anti-theft and anti-interference power metering box according to claim 1, characterized in that, The controller is configured with an RF transmission shielding mode and a dynamic impedance monitoring mode; The radio frequency transmission shielding mode is as follows: during the period when the radio frequency transceiver branch transmits radio frequency signals, the controller shields the interrupt response from the DC anti-tamper branch to prevent radio frequency level fluctuations from causing false triggering of the anti-tamper function. The dynamic impedance monitoring mode is as follows: during the period when the radio frequency transceiver branch transmits radio frequency signals, the controller periodically acquires the standing wave ratio (SWR) parameter of the conductive mesh (2); and when the rate of change of the SWR parameter is lower than the set drift threshold, the dynamic reference value is updated; when the difference between the current SWR parameter and the dynamic reference value is greater than the anti-tamper judgment threshold within the preset time window and the state of the difference being greater than the anti-tamper judgment threshold remains unrecoverable, it is determined that the conductive mesh (2) has physically broken, and an anti-tamper trigger signal is output.

3. The anti-theft and anti-interference power metering box according to claim 2, characterized in that, The back of the conductive mesh (2) is composited with a non-metallic mechanical stress wire (3). One end of the mechanical stress wire (3) is fixed to the inner wall of the box (1), and the other end is tensioned and connected to a spring energy storage micro switch (4). The metering box is also equipped with a backup power supply circuit, a backup battery and an alarm module that are independent of the main power supply circuit. The spring energy storage micro switch (4) and the alarm module are connected in series in the backup power supply circuit. Under normal conditions, the mechanical stress wire (3) is in a taut state and overcomes the elastic force of the spring energy storage micro switch (4), keeping its contacts open; when the mechanical stress wire (3) breaks, the spring energy storage micro switch (4) loses its tension constraint and uses the internal spring potential energy to close the contacts, thereby connecting the backup battery and the alarm module.

4. The anti-theft and anti-interference power metering box according to claim 3, characterized in that, The backup power supply circuit also integrates an electronic latching branch, which is connected in parallel with the spring energy storage micro switch (4). The electronic latching branch includes a P-channel MOSFET and a pull-down resistor. The gate of the P-channel MOSFET is connected to a high level through the DC anti-tamper branch to maintain the off state. The pull-down resistor is connected between the gate and ground. When the conductive grid (2) is physically broken or the main power supply circuit is de-energized, the DC anti-tamper branch is opened or de-energized. The gate is pulled down to the conduction threshold through the pull-down resistor, and the P-channel MOSFET is turned on to trigger the backup battery to supply power to the controller.

5. The anti-theft and anti-interference power metering box according to claim 4, characterized in that, It also includes multiple magnetic field sensors distributed at different locations within the housing (1), and the controller is communicatively connected to each of the magnetic field sensors to perform the following steps: The real-time magnetic field strength output by the magnetic field sensor is obtained, and the rate of change of the magnetic field strength is calculated. If the rate of change is greater than the set rate of change threshold and falls back to the normal reference range within a preset time, it is determined to be a transient power grid interference and the current magnetic field data is ignored. If the real-time magnetic field strength is greater than the set static amplitude threshold, or the time-domain rate of change is greater than the rate of change threshold and does not fall back within the preset time, then the magnetic field gradient between each magnetic field sensor is calculated; when the magnetic field gradient is greater than the set gradient threshold, an abnormal signal is output.

6. The anti-theft and anti-interference power metering box according to claim 5, characterized in that, When the number of magnetic field sensors that output full-scale saturation signals exceeds a set threshold, the controller stops calculating the magnetic field gradient and directly outputs the abnormal signal.

7. The anti-theft and anti-interference power metering box according to claim 6, characterized in that, It also includes an adaptive power management module, which includes a backup battery and a battery discharge activation circuit electrically connected to the backup battery; The controller is configured to: acquire the resting time parameter and ambient temperature parameter of the backup battery; and calculate the battery resting time parameter based on the resting time parameter and the ambient temperature parameter. When the main power supply circuit is determined to be normal and the battery resting time parameter reaches the preset passivation threshold, the controller controls the battery discharge activation circuit to be turned on; wherein, the controller controls the battery discharge activation circuit by outputting a pulse width modulation signal with a step-increasing duty cycle, so as to perform pulse depassivation discharge on the backup battery.

8. The anti-theft and anti-interference power metering box according to claim 7, characterized in that, The controller has a circular buffer allocated within it and is communicatively connected to a non-volatile memory; the controller is configured as follows: Under normal monitoring conditions, the sampled data is cyclically overwritten into the circular buffer in a first-in-first-out manner, and the hash value of the current data in the circular buffer is periodically extracted and uploaded. When the abnormal signal or the tamper-proof trigger signal is obtained, the controller freezes the current write address of the ring buffer, extracts the sampled data before and after the trigger moment as a data storage data packet, and writes the data storage data packet into the non-volatile memory.

9. The anti-theft and anti-interference power metering box according to claim 8, characterized in that, When the metering box is damaged, causing the conductive mesh (2) and the mechanical stress wire (3) to break, the micro switch (4) closes, connecting the power supply circuit from the backup battery to the alarm module and waking up the alarm module. At the same time, the controller uses the backup power provided by the electronic latch branch to perform the write operation of the evidence data packet to the non-volatile memory. After the write operation is completed, the controller transmits the evidence data packet to the alarm module, which is already in operation, through the communication bus between itself and the alarm module. The alarm module then broadcasts an alarm signal carrying the device identifier and the evidence data packet.

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