A cable branch box status data telemetry system

Abstract

The application relates to the technical field of measurement value and control signal transmission, and discloses a cable branch box state data telemetry system, which comprises a branch state sensing and telemetry sending module, a link arbitration and timing control transmission module and a fee control response and state feedback closed loop module.The branch state sensing and telemetry sending module adaptively sends steady-state compressed differential frames or transient complete frames according to state change degrees.The link arbitration and timing control transmission module inserts a protection time slot in response to a tripping instruction, detects a differential level idle state, encounters a disturbance pulse, then extends a time slot until the level continuously and stably idles, and broadcasts a pre-emptive control token frame.The fee control response and state feedback closed loop module drives a separation according to the token frame and returns an acknowledgement frame.The application decouples a burst instruction from a polling sequence through a time slot injection and a level detection mechanism, eliminates link transmission conflicts and avoids electromagnetic interference, and improves system transmission reliability.

Description

Technical Field

[0001] This invention relates to a cable branch box status data telemetry system, belonging to the field of measurement value and control signal transmission technology. Background Technology

[0002] In the automated operation of power distribution networks, cable branch boxes are mainly responsible for the distribution of power across multiple circuits and the monitoring of their operating status. In order to grasp the real-time operating conditions of each branch circuit and to perform load control when operating parameters exceed limits, sensor acquisition modules are usually installed in each branch circuit inside the box. These modules are connected to the centralized management equipment via a half-duplex differential bus. The centralized management equipment adopts a master-slave periodic polling method to receive measured values ​​such as bus voltage, branch phase current, joint temperature, and insulation leakage current uploaded by each branch circuit. Upon receiving remote control commands, it drives the designated circuit breaker to operate.

[0003] Due to the limited internal space and numerous outgoing circuits in cable branch boxes, monitoring nodes typically share the same physical channel. To alleviate the management complexity caused by multi-node monitoring, existing technologies primarily improve upon this by expanding the sensing layer hardware and centralizing threshold comparison. However, significant shortcomings remain in data transmission scheduling and control timing. For instance, Chinese invention patent application CN106597961A discloses a ring main unit environmental monitoring system and method. This system deploys temperature and current sensors at multiple locations, such as cable taps and fastening sleeves, to centrally transmit collected operating parameters to a controller for comparison with set standard values. It also disconnects fault intervals in case of an anomaly. While this solution covers heat-prone areas by expanding sensing hardware, it relies on periodic, centralized reporting of full data. Furthermore, each sensing node does not process steady-state changes. Dynamic compression can easily exacerbate the communication load of the half-duplex bus when multiple monitoring points upload data concurrently. As the number of monitoring parameters increases and the sampling frequency rises, the continuous uploading of full measurement data by each node will cause the half-duplex bus to be under high communication load for a long time. When the remote end suddenly sends a control signal with specific requirements for response timing, or when a branch circuit suddenly fails, the control signal can only queue and wait for the current polling cycle to end due to the limitation of the conventional polling order. This can easily lead to channel arbitration conflicts and transmission waiting delays. At the same time, the opening and closing of the circuit breaker will generate arc discharge and high-frequency transient electromagnetic pulses. Existing communication procedures usually cannot determine whether the differential level of the bus physical layer is still in an oscillating state. Messages may be sent before strong interference has completely attenuated, which may cause false start bit determination of the bus, abnormal data frame structure, and verification failure.

[0004] Therefore, in the case of multiple branch circuits sharing a half-duplex physical bus, how to reduce the occupation of channel bandwidth by steady-state measurement value transmission, avoid transient electromagnetic interference according to the physical layer level state when a sudden control signal is inserted, and form a closed-loop transmission mode that includes local electrical state confirmation, has become the technical problem to be solved by this invention. Summary of the Invention

[0005] To address the problems in the background art, the technical solution of the present invention is as follows: A cable branch box status data telemetry system, comprising: Each branch status perception and telemetry transmission module, and each cost control response and status feedback closed-loop module are connected to the link arbitration and timing control transmission module via a half-duplex RS485 communication bus. The branch status sensing and telemetry transmission module is used to collect the operating electrical parameters and joint temperature of the corresponding cable branch circuit, determine the operating status based on the degree of status change, and send a steady-state compressed differential frame to the half-duplex RS485 communication bus when the degree of status change is not greater than the preset steady-state disturbance threshold, and send a complete transient event frame when the degree of status change is greater than the preset steady-state disturbance threshold. The link arbitration and timing control transmission module is used to distribute polling tokens on the half-duplex RS485 communication bus. In response to the remote trip control command, it inserts a protection time slot at the end of the current transmission data frame and suspends the polling timing. Differential level idle detection is performed within the protection time slot. When a disturbance pulse is detected, the protection time slot is extended until the bus level is continuously at the idle bias level to reach the preset silence maintenance time. Then, a preemptive control token frame is broadcast. The fee control response and status feedback closed-loop module is used to reply with an acknowledgment frame to the half-duplex RS485 communication bus after the verification of the preemptive control token frame passes, output the tripping signal, determine the completion of the tripping action based on the node change level and the phase current returning to zero, and send the tripping action confirmation status frame to the link arbitration and timing control transmission module in the first time slot after the bus resumes polling.

[0006] Preferably, the degree of state change The following formula is used to calculate: ,in, , , The corresponding cable branch circuits are in the 1st The effective values ​​of phase current, junction temperature and zero-sequence current were collected at each sampling time. , , These are the baseline values ​​corresponding to the previous update time; This is the reference value for the rated operating current of the circuit. This is the rated temperature limit reference value for the connector. This is the zero-sequence current alarm threshold value; , , The weighting coefficients are dimensionless and satisfy the following conditions: ; The sampling period.

[0007] Preferably, the preset steady-state disturbance threshold is in the range of 0.03 to 0.08; when the degree of state change is not greater than the preset steady-state disturbance threshold, the branch state sensing and telemetry transmission module keeps the reference value of the previous update time unchanged; when the degree of state change is greater than the preset steady-state disturbance threshold, the branch state sensing and telemetry transmission module updates the effective value of phase current, junction temperature and effective value of zero-sequence current collected at the current sampling time to the reference value of the next cycle.

[0008] Preferably, when the cumulative number of consecutive transmissions of steady-state compressed differential frames by the branch state perception and telemetry transmission module reaches the preset cumulative period limit, the module sends a reference reset frame containing all physical state parameters to the half-duplex RS485 communication bus within the current polling time slot, and resets all physical state parameters to the new reference values ​​for subsequent differential calculations; wherein, the preset cumulative period limit is 30 to 80 polling periods.

[0009] Preferably, the length of the steady-state compressed differential frame is 6B to 10B, and the frame contains quantized encoded data of the phase current difference and the joint temperature difference; the length of the transient event complete frame is 28B to 36B, the frame header contains an emergency telemetry flag, and the frame body contains the RMS value of the full-phase current, the joint temperature, the RMS value of the zero-sequence current, and the insulation leakage current.

[0010] Preferably, the branch state perception and telemetry transmission module includes a multi-parameter sensing acquisition module, a differential quantization encoder, and a bus transceiver driver; the multi-parameter sensing acquisition module is connected to the cable branch loop to synchronously acquire analog sensing signals and convert them into operating electrical parameters and connector temperatures; the differential quantization encoder is connected to the multi-parameter sensing acquisition module to encode discrete physical quantities according to the degree of state change to generate corresponding data frames in steady-state compressed differential frames and transient event complete frames; the bus transceiver driver is connected to the differential quantization encoder and a half-duplex RS485 communication bus to modulate the encoded data frames into differential physical signals in response to the bus polling token.

[0011] Preferably, the link arbitration and timing control transmission module includes a bus time slot management module, a dual-priority transmission arbitration module, and an uplink remote communication interface. The bus time slot management module is used to construct a dynamic time-division polling sequence on the half-duplex RS485 communication bus and sequentially issue polling tokens to each branch status sensing and telemetry sending module according to a preset time slot allocation table. The dual-priority transmission arbitration module is connected to the bus time slot management module and the uplink remote communication interface, and is used to insert a protection time slot when a remote trip control command is received, and control the bus time slot management module to interrupt the current polling sequence. The uplink remote communication interface is used to establish a communication link with the remote master station.

[0012] Preferably, the basic duration of the protection time slot is 3.00ms to 8.00ms; the link arbitration and timing control transmission module continuously applies an idle bias level to the half-duplex RS485 communication bus within the protection time slot. If the duration of the transient interference pulse on the differential line exceeds the basic duration, the protection time slot will be extended until the bus is continuously in an idle bias state without pulse disturbance to reach the preset silent maintenance time.

[0013] Preferably, the fee control response and status feedback closed-loop module includes a control command parsing and verification module, a tripping and closing timing drive module, and a switch status local feedback module. The control command parsing and verification module is used to parse the target circuit physical address code, control function code, and cyclic redundancy check code in the preemptive control token frame, and outputs a trigger enable signal when the physical address matches and the verification passes. The tripping and closing timing drive module is connected to the control command parsing and verification module and is used to output a tripping pulse to the switch node tripping circuit in response to the trigger enable signal.

[0014] Preferably, the local feedback module for switch status is connected to the auxiliary contact of the switch node and the current transformer for acquiring the phase current of the circuit, respectively. When a change in the level of the auxiliary contact is detected and the effective value of the phase current of the circuit falls below the disconnection judgment threshold, telemetry data indicating successful tripping action is generated. After the link arbitration and timing control transmission module resumes bus polling, the fee control response and status feedback closed-loop module prioritizes sending the tripping action confirmation status frame in the first available polling time slot.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In the telemetry of cable branch box status data, the differential quantization encoder generates steady-state compressed differential frames or transient event complete frames based on the status changes of each branch circuit. This allows only the changes to be transmitted when the operation is stable, reducing the long-term occupation of the half-duplex RS485 communication bus bandwidth by steady-state telemetry data. This reserves more available transmission time for sudden control signals, reduces queuing and transmission conflicts caused by periodic polling of sudden control signals, and shortens the response time when telemetry data and control signals share the communication link.

[0016] 2. After continuously sending steady-state compressed differential frames for a certain period, the differential calculation reference is re-established by resetting the reference frame. This can limit the continuous accumulation of small truncation errors during long-term differential quantization, avoid the gradual shift of the reference causing distortion of remote telemetry data, maintain low bus bandwidth usage, and improve the reconstruction accuracy and resolution consistency of measurement data during long-term transmission.

[0017] 3. By setting a protection time slot before sending a sudden control signal and judging whether the interference has been attenuated based on the actual level of the half-duplex RS485 communication bus, the transient electromagnetic interference generated by the switching action can be avoided before sending the control message. This can reduce false start bit judgment, abnormal data frame structure and verification failure caused by strong interference, reduce the probability of control commands being transmitted incorrectly or lost due to electromagnetic interference, and improve the reliability of control signal issuance. Attached Figure Description

[0018] Figure 1 This is a diagram illustrating the multi-module bus communication and data interaction of the present invention; Figure 2 This is a diagram of the multi-parameter sensing acquisition and differential quantization coding structure of the present invention.

[0019] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0021] A cable branch box status data telemetry system, comprising: Each branch status perception and telemetry transmission module, and each cost control response and status feedback closed-loop module are connected to the link arbitration and timing control transmission module via a half-duplex RS485 communication bus. The branch status sensing and telemetry transmission module is used to collect the operating electrical parameters and joint temperature of the corresponding cable branch circuit, determine the operating status based on the degree of status change, and send a steady-state compressed differential frame to the half-duplex RS485 communication bus when the degree of status change is not greater than the preset steady-state disturbance threshold, and send a complete transient event frame when the degree of status change is greater than the preset steady-state disturbance threshold. The link arbitration and timing control transmission module is used to distribute polling tokens on the half-duplex RS485 communication bus. In response to the remote trip control command, it inserts a protection time slot at the end of the current transmission data frame and suspends the polling timing. Differential level idle detection is performed within the protection time slot. When a disturbance pulse is detected, the protection time slot is extended until the bus level is continuously at the idle bias level to reach the preset silence maintenance time. Then, a preemptive control token frame is broadcast. The fee control response and status feedback closed-loop module is used to reply with an acknowledgment frame to the half-duplex RS485 communication bus after the verification of the preemptive control token frame passes, output the tripping signal, determine the completion of the tripping action based on the node change level and the phase current returning to zero, and send the tripping action confirmation status frame to the link arbitration and timing control transmission module in the first time slot after the bus resumes polling.

[0022] Preferably, the degree of state change The following formula is used to calculate: ,in, , , The corresponding cable branch circuits are in the 1st The effective values ​​of phase current, junction temperature and zero-sequence current were collected at each sampling time. , , These are the baseline values ​​corresponding to the previous update time; This is the reference value for the rated operating current of the circuit. This is the rated temperature limit reference value for the connector. This is the zero-sequence current alarm threshold value; , , The weighting coefficients are dimensionless and satisfy the following conditions: ; The sampling period.

[0023] Preferably, the preset steady-state disturbance threshold is in the range of 0.03 to 0.08; when the degree of state change is not greater than the preset steady-state disturbance threshold, the branch state sensing and telemetry transmission module keeps the reference value of the previous update time unchanged; when the degree of state change is greater than the preset steady-state disturbance threshold, the branch state sensing and telemetry transmission module updates the effective value of phase current, junction temperature and effective value of zero-sequence current collected at the current sampling time to the reference value of the next cycle.

[0024] Preferably, when the cumulative number of consecutive transmissions of steady-state compressed differential frames by the branch state perception and telemetry transmission module reaches the preset cumulative period limit, the module sends a reference reset frame containing all physical state parameters to the half-duplex RS485 communication bus within the current polling time slot, and resets all physical state parameters to the new reference values ​​for subsequent differential calculations; wherein, the preset cumulative period limit is 30 to 80 polling periods.

[0025] Preferably, the length of the steady-state compressed differential frame is 6B to 10B, and the frame contains quantized encoded data of the phase current difference and the joint temperature difference; the length of the transient event complete frame is 28B to 36B, the frame header contains an emergency telemetry flag, and the frame body contains the RMS value of the full-phase current, the joint temperature, the RMS value of the zero-sequence current, and the insulation leakage current.

[0026] Preferably, the branch state perception and telemetry transmission module includes a multi-parameter sensing acquisition module, a differential quantization encoder, and a bus transceiver driver; the multi-parameter sensing acquisition module is connected to the cable branch loop to synchronously acquire analog sensing signals and convert them into operating electrical parameters and connector temperatures; the differential quantization encoder is connected to the multi-parameter sensing acquisition module to encode discrete physical quantities according to the degree of state change to generate corresponding data frames in steady-state compressed differential frames and transient event complete frames; the bus transceiver driver is connected to the differential quantization encoder and a half-duplex RS485 communication bus to modulate the encoded data frames into differential physical signals in response to the bus polling token.

[0027] Preferably, the link arbitration and timing control transmission module includes a bus time slot management module, a dual-priority transmission arbitration module, and an uplink remote communication interface. The bus time slot management module is used to construct a dynamic time-division polling sequence on the half-duplex RS485 communication bus and sequentially issue polling tokens to each branch status sensing and telemetry sending module according to a preset time slot allocation table. The dual-priority transmission arbitration module is connected to the bus time slot management module and the uplink remote communication interface, and is used to insert a protection time slot when a remote trip control command is received, and control the bus time slot management module to interrupt the current polling sequence. The uplink remote communication interface is used to establish a communication link with the remote master station.

[0028] Preferably, the basic duration of the protection time slot is 3.00ms to 8.00ms; the link arbitration and timing control transmission module continuously applies an idle bias level to the half-duplex RS485 communication bus within the protection time slot. If the duration of the transient interference pulse on the differential line exceeds the basic duration, the protection time slot will be extended until the bus is continuously in an idle bias state without pulse disturbance to reach the preset silent maintenance time.

[0029] Preferably, the fee control response and status feedback closed-loop module includes a control command parsing and verification module, a tripping and closing timing drive module, and a switch status local feedback module. The control command parsing and verification module is used to parse the target circuit physical address code, control function code, and cyclic redundancy check code in the preemptive control token frame, and outputs a trigger enable signal when the physical address matches and the verification passes. The tripping and closing timing drive module is connected to the control command parsing and verification module and is used to output a tripping pulse to the switch node tripping circuit in response to the trigger enable signal.

[0030] Preferably, the local feedback module for switch status is connected to the auxiliary contact of the switch node and the current transformer for acquiring the phase current of the circuit, respectively. When a change in the level of the auxiliary contact is detected and the effective value of the phase current of the circuit falls below the disconnection judgment threshold, telemetry data indicating successful tripping action is generated. After the link arbitration and timing control transmission module resumes bus polling, the fee control response and status feedback closed-loop module prioritizes sending the tripping action confirmation status frame in the first available polling time slot.

[0031] Example 1: In a 10kV outdoor cable branch box equipped with 6 outgoing cable branch circuits, the multi-parameter sensing and acquisition module of each branch status sensing and telemetry transmission module is connected to the miniature Rogowski coil, the through-type zero-sequence current transformer, and the temperature sensor at the corresponding branch cable joint to collect the effective value of each phase current. Connector temperature With the effective value of zero-sequence current It connects to a 9600bps half-duplex RS485 communication bus via an isolated differential transceiver chip. The differential quantization encoder calculates the degree of state change based on the phase current deviation ratio, connector temperature deviation ratio, and zero-sequence current deviation ratio. Its mathematical expression is as follows: ,in, , , The corresponding cable branch circuits are in the 1st The effective values ​​of phase current, junction temperature, and zero-sequence current were collected at each sampling time. , , These are the baseline values ​​corresponding to the previous update time. The rated operating current of the circuit is set to 630A. The rated temperature limit of the connector is set to 100℃. The zero-sequence current alarm threshold is set to 30A. , , The dimensionless weighting coefficients are set to 0.7, 0.2, and 0.1 respectively, satisfying the following conditions: , With a sampling period set to 200ms, when the first circuit is in a stable fluctuating condition, the sampled phase current changes from a reference value of 210A to 212.5A, the connector temperature changes from a reference value of 45℃ to 45.2℃, and the zero-sequence current changes from a reference value of 1.2A to 1.3A. The degree of state change is then calculated. Its value is not greater than the preset steady-state disturbance threshold of 0.05. The differential quantization encoder maintains the original reference value unchanged, and the generated byte length is... The steady-state compressed differential frame is 8 bytes long and modulated by the bus transceiver driver before being sent to the half-duplex RS485 communication bus. The transmission time for a single frame is 8.33 ms. In the fixed-length mapping of the differential quantization encoder, the 8-byte data structure of the steady-state compressed differential frame is allocated as follows: the first byte is the slave physical address, the second byte is the steady-state frame function identifier code, the third and fourth bytes are 16-bit signed phase current difference quantization code, where the highest bit is the sign bit and the lower 15 bits are the absolute difference integer quantization values ​​with a quantization step size of 0.1A; the fifth and sixth bytes are 16-bit signed junction temperature difference quantization code, where the highest bit is the sign bit and the lower 15 bits are the absolute difference integer quantization values ​​with a quantization step size of 0.01℃; the seventh and eighth bytes are the 16-bit cyclic redundancy check code of the entire frame, which compresses the floating-point physical quantity difference into a discrete fixed-length byte stream.

[0032] When each branch loop continues to operate smoothly and the cumulative number of transmission cycles of steady-state compressed differential frames reaches the preset cumulative cycle limit of 50 polling cycles. At that time, the branch state sensing and telemetry transmission module sends a reference reset frame containing all physical state parameters to the half-duplex RS485 communication bus within the current polling time slot, and resets all physical state parameters in the reference reset frame to the new reference values ​​for subsequent differential calculations. This prevents the continuous accumulation of micro-amplitude truncation errors caused by low-bit-width quantization during long-cycle transmission. When an overload disturbance occurs in a certain outgoing circuit, the phase current suddenly increases to 380A, the connector temperature rises to 52℃, and the zero-sequence current is 1.3A, the state change degree is calculated. If the value exceeds the preset steady-state disturbance threshold of 0.05, the differential quantization encoder switches to full parametric encoding, generating a byte length of... For a complete 32B transient event frame, the emergency telemetry flag is set in the frame header, and the effective values ​​of the phase current, junction temperature and zero-sequence current collected at the current sampling time are updated to the reference values ​​for the next cycle. The transmission time for a single frame is 33.33ms.

[0033] During the distribution of regular polling tokens by the bus time slot management module of the link arbitration and timing control transmission module, the uplink remote communication interface receives a trip control command issued by the remote master station for a specified circuit. The dual-priority transmission arbitration module inserts a protection time slot with a basic duration of 5ms at the end of the currently transmitted 8B steady-state compressed differential frame. Simultaneously, the polling sequence is suspended, and the bus time slot management module protects the time slot. An idle bias level is continuously applied to the half-duplex RS485 communication bus, and differential level idle detection is performed. When a transient disturbance pulse is detected due to a pre-trip condition of the switch or coupling into the differential line by external electromagnetic environment, its duration is detected. If the duration of the transient interference pulse exceeds the basic duration of 5ms, the protection time slot is extended until the bus is continuously in an idle bias state without pulse disturbance for a preset silence duration. Then, the broadcast byte length is determined. The preemptive control token frame is 12B, with a single frame transmission time of 12.5ms. This ensures that the broadcast of sudden control commands avoids transient electromagnetic noise in the physical channel. External electromagnetic disturbance pulses detected within this protection time slot include the arc of the preceding short-circuit fault in the power grid that triggered this remote trip control command, the spatial radiation transient electromagnetic interference associated with the overcurrent interruption of adjacent parallel branch circuits in the box, and the contactor jitter electromagnetic noise caused by the voltage drop of the distribution bus. When the remote trip control command is triggered, the internal channel of the cable branch box is in the overlapping period of the existing fault transient pulse train. Therefore, differential level idle detection is performed before the preemptive control token frame is issued, and the protection time slot is extended when the duration of the transient interference pulse exceeds the basic duration of the protection time slot. The preemptive control token frame is broadcast only after the bus level continuously meets the idle bias state.

[0034] The target loop's fee control response and status feedback closed-loop module parses the target loop's physical address code, control function code, and cyclic redundancy check code in the preemptive control token frame through the control command parsing and verification module. When the physical address matches and the verification passes, it outputs a trigger enable signal and replies with a byte length to the half-duplex RS485 communication bus within a 2ms hardware response window. The confirmation frame is 8B. Subsequently, the opening and closing timing drive module outputs the opening trip signal to the switch node. After the circuit breaker operates, the local feedback module of the switch status synchronously acquires the node change level and the zero-state of the circuit phase current. When both meet the disconnection criterion, telemetry data representing the successful opening action is generated. After the link arbitration and timing control transmission module resumes bus polling, the fee control response and status feedback closed-loop module prioritizes sending the opening action confirmation status frame in the first available polling time slot, completing the control command issuance, local mechanism action, electrical and physical disconnection judgment and status feedback.

[0035] Total bus interaction time from receiving the remote trip command to receiving the local loop confirmation frame from the self-link arbitration and timing control transmission module. satisfy: Compared to the queuing delay caused by multi-node static full-quantum message polling, this transmission timing shortens the waiting time for sudden control commands. Steady-state differential quantization transmission reduces the steady-state occupancy of the half-duplex physical bus. The protection time slot based on differential level idle detection allows the preemptive control token frame to be sent after the bus returns to idle. This ensures that sudden remote control signals when dense circuits share the half-duplex physical channel are within a defined microsecond to millisecond timing response window. After the circuit breaker is tripped, the tripping action is confirmed by the node change level and the phase current returning to zero. This reduces communication malfunctions under electromagnetic noise interference and allows telemetry measurement data transmission and emergency control signal delivery to be completed on the same physical bus according to their respective timing sequences.

[0036] Example 2: A cable branch box status data telemetry system was deployed on a simulation test platform containing six 10kV outgoing cable branch circuits. Each circuit used a miniature Rogowski coil with phase current measurement accuracy better than 0.5%, a through-type zero-sequence current transformer, and a digital temperature sensor with a temperature resolution of 0.1℃ to collect operating parameters. These parameters were then connected to a half-duplex RS485 communication bus with a working baud rate of 9600bps via a 50m shielded twisted-pair cable. During the test, a high-voltage pulse generator injected a transient high-frequency electromagnetic interference pulse group with an amplitude of 2.5kV, a repetition frequency of 100kHz, and a pulse train duration varying from 2.00ms to 6.50ms into the bus differential line at the moment the circuit breaker tripped. This was used to simulate the disturbance of arc discharge to the differential level of the half-duplex physical bus. Each test group ran continuously for 60 minutes, collecting input parameters during continuous load fluctuations and sudden tripping control of multiple circuits. The steady-state bus occupancy rate, telemetry reconstruction mean absolute error, and total delay of control command issuance were statistically analyzed. And the success rate of control command verification.

[0037] During the test, a preset steady-state disturbance threshold was used. The value range is from 0.03 to 0.08. The lower limit of 0.03 corresponds to the tolerance for sensor acquisition noise and small fluctuations in power frequency, while the upper limit of 0.08 corresponds to the critical point where the cable load evolution shows a trend deviation. In the setting of the threshold boundary, the lower limit of 0.03 is determined based on the 0.5% measurement error of the current transformer plus the 2% steady-state fluctuation of the power frequency in the distribution network. When the threshold is below 0.03, normal fluctuations will frequently trigger complete frames of transient events. The upper limit of 0.08 corresponds to the load step point where the phase current sudden change reaches 5% of the rated value. When the threshold is above 0.08, moderate overload may still remain in differential compression state, and the protection time slot... The base duration is set to 3.00ms to 8.00ms, where 3.00ms covers the peak arc energy release period during the initial mechanical action of the circuit breaker's auxiliary contacts, and 8.00ms corresponds to the oscillation window of arc transient decay. An upper limit for the preset accumulation period is also included. The polling cycle is set to 30 to 80 times, with 30 times corresponding to a 6-second mandatory reference calibration time and 80 times corresponding to a 16-second running span. The low-order truncation error is linearly accumulated at a maximum of 0.005% per cycle, and when the cumulative error reaches 80 times, it approaches the upper limit of the system's allowable comprehensive error of 0.4%.

[0038] To examine the impact of a preset steady-state disturbance threshold on data transmission, sample group 1 of this invention will... Set to 0.03. Set to 5ms With a duration of 3.2 ms for the injected transient disturbance, the steady-state bus occupancy rate was 28.4% and the mean absolute error of telemetry reconfiguration was 0.18% when the number of cycles was set to 50. The time was 27.83ms, and the control command verification success rate was 100%. Sample group 2 of this invention will... Set to 0.05. Set to 5ms With a timeout of 3.2ms and 50 cycles, the steady-state bus utilization rate was 22.6%, and the mean absolute error of telemetry reconfiguration was 0.32%. The time was 27.83ms, and the control command verification success rate was 100%. Sample group 3 of this invention will... Set to 0.08 Set to 5ms With a timeout of 3.2ms and 50 cycles, the steady-state bus utilization rate dropped to 18.2%, and the mean absolute error of telemetry reconfiguration was 0.54%. The time remains at 27.83ms, and the control command verification success rate is 100%. The test results show that, with other test parameters kept at the same settings, as the preset steady-state disturbance threshold increases from 0.03 to 0.08, the range of states entering steady-state compressed differential frame transmission expands accordingly, the steady-state bus occupancy rate decreases, and the telemetry reconstruction mean absolute error increases accordingly.

[0039] When comparing values ​​outside the threshold range, control group 4 used a smaller out-of-range threshold. Set to 0.02. Set to 5ms With a timeout of 3.2ms and 50 cycles, the steady-state bus utilization rate was 54.3%, and the mean absolute error of telemetry reconfiguration was 0.14%. The time was 27.83ms, and the control command verification success rate was 100%. At this time, minor environmental disturbances frequently triggered complete 32B transient event frames, increasing the bus steady-state occupancy rate. Control group 5 used a relatively large out-of-range threshold. Set to 0.12. Set to 5ms With a timeout of 3.2ms and a duration of 50 cycles, the steady-state bus utilization rate was 16.5%, and the mean absolute error of telemetry reconfiguration increased to 1.42%. The time is 27.83ms, and the control command verification success rate is 100%. At this time, the differential quantization encoder lags behind the response of the phase current to the moderate load fluctuation, so that more changes continue to be processed according to the steady-state compressed differential frame.

[0040] To investigate the impact of the protection time slot duration on control transmission timing, sample group 4 of this invention will... Set to 0.05. Set to 3ms With a duration of 2.1 ms for the injected transient disturbance, the steady-state bus occupancy rate was 22.6% and the mean absolute error of telemetry reconfiguration was 0.32% when the number of cycles was set to 50. The time was 25.83ms, and the control command verification success rate was 100%. Sample group 5 of this invention will... Set to 0.05. Set to 8ms With a duration of 5.8 ms for the injected transient disturbance, the steady-state bus utilization rate was 22.6%, and the mean absolute error of telemetry reconfiguration was 0.32%. The timeout was 30.83ms, and the control command verification success rate was 100%. In both sets of tests, the bus time slot management module performed differential level idle detection within the protection time slot and broadcast a preemptive control token frame after the bus was in a continuously idle bias state without pulse disturbance for a preset silent maintenance time. When the basic duration of the protection time slot increased from 3ms to 8ms, the corresponding total delay of the control command issuance increased from 25.83ms to 30.83ms.

[0041] Control group 2 was used to examine the transmission situation during the missing level listening delay. The value is 0.05, and the protection time slot is fixed at 5ms. The number of injections was 50, the duration of transient disturbances was extended to 6.5 ms, the steady-state bus occupancy rate was 22.6%, and the mean absolute error of telemetry reconstructing was 0.32%. The duration was 27.83ms, and the success rate of control command verification dropped to 68.5%. This group continued to send command frames according to the fixed time slot after the duration of the transient interference pulse exceeded the basic duration of the protection time slot of 5ms. The protection time slot was not extended according to the differential level idle state. Therefore, the command frame entered the transient interference period that had not yet fully decayed.

[0042] To investigate the impact of a preset upper limit for the accumulation period on long-term differential transmission errors, sample group 6 of this invention will... Set to 0.05. Set to 5ms With 30 cycles and a 3.2ms transient disturbance, the steady-state bus utilization rate was 24.1%, and the mean absolute error of telemetry reconfiguration was 0.22%. The time was 27.83ms, and the control command verification success rate was 100%. Sample group 7 of this invention will... Set to 0.05. Set to 5ms With 80 cycles and a 3.2ms transient disturbance, the steady-state bus utilization rate was 21.5%, and the mean absolute error of telemetry reconfiguration was 0.48%. The time interval is 27.83ms, the control command verification success rate is 100%, and both groups send a reference reset frame containing all physical state parameters when the accumulation period of the steady-state compressed differential frame reaches the upper limit of the preset accumulation period. The reference value for subsequent differential calculation is reset with all physical state parameters. As the reset interval is extended from 30 polling cycles to 80 polling cycles, the bus time occupied by the steady-state message is reduced, while the differential quantization truncation error allowed to accumulate before the reference reset is correspondingly increased.

[0043] Control group 3 cancels the cumulative benchmark reset mechanism. 0.05 With a preset accumulation period of 5ms and a no-reset mechanism, under a 3.2ms transient disturbance, the steady-state bus utilization rate is 20.8%, and the average absolute error of telemetry reconstructing reaches 2.86%. The time to transmit the data is 27.83ms, the control command verification success rate is 100%, and during continuous steady-state operation, this group does not send a reference reset frame. The differential quantization truncation error continues to accumulate with the transmission cycle. Compared with the reference reset processing of sample group 6 and sample group 7 of the present invention within 30 to 80 polling cycles, the telemetry reconstruction error of this group continues to increase.

[0044] Control group 1 uses conventional static full polling without differential compression, protection time slots, or a reference reset mechanism. When the injected transient disturbance lasts for 3.2ms, master-slave polling is performed using 32B full messages. The steady-state bus occupancy rate reaches 72.8%, the telemetry reconstruction mean absolute error is 0.15%, and sudden control commands need to wait for the current polling cycle to end. The time reached 396.4ms, and the control command verification success rate was 74.2%. This group maintained a low telemetry reconstruction error when directly sending full messages, but continuous full polling occupied a lot of bus time. At the same time, due to the lack of protection time slots and differential level detection, the control command verification success rate decreased when sending control messages during arc transient interference.

[0045] In the above tests, the transmission ratio of steady-state compressed differential frames is controlled by a preset steady-state disturbance threshold, the transmission interval of reference reset frames is controlled by a preset upper limit of the cumulative period, and the broadcast time of burst control commands is determined by differential level idle detection within the protection time slot. The corresponding data shows that when the preset steady-state disturbance threshold changes, the bus steady-state occupancy rate and the average absolute error of telemetry reconstruction change accordingly; when the preset upper limit of the cumulative period changes, the reference reset frequency and the long-term reconstruction error change accordingly; under the condition that strong transient interference continues to exceed the fixed protection time slot, the lack of differential level monitoring and delay processing will reduce the success rate of control command verification. The three processing measures are applied to the steady-state telemetry data volume, the long-term differential reference, and the burst control transmission timing, respectively, and are used together for the transmission of telemetry data and control signals when multiple branch circuits share a half-duplex RS485 communication bus.

[0046] Example 3: A 10kV outdoor cable branch box containing 6 outgoing cable branch circuits is used for field deployment in this example. The multi-parameter sensing and acquisition module of the branch status sensing and telemetry transmission module, through an electromagnetically isolated analog sampling front-end and a high-precision analog-to-digital converter, senses the electromotive force of each phase AC current through a miniature Rogowski coil at the cable joint, and generates the effective value of the phase current after integration processing. The effective value of the zero-sequence current is obtained from a through-type zero-sequence current transformer. The joint temperature is read by a digital temperature sensor embedded in the inner wall of the insulating sleeve. The discrete register group of the differential quantization encoder temporarily stores the reference value corresponding to the previous update time. , and During the sampling period Under a 200ms clock interrupt trigger, calculate the absolute values ​​of the phase current change, the junction temperature change, and the zero-sequence current change, and substitute them into the circuit's rated operating current reference value set at 630A. The rated temperature limit of the connector is set at 100℃. With the zero-sequence current alarm threshold set at 30A Complete the normalized division calculation, and then combine it with the weighting coefficients. , and Linear weighted summation generates the degree of state change. When the degree of state change The steady-state disturbance threshold is not greater than the preset value of 0.05. At this time, the differential quantization encoder keeps the current reference value unchanged and extracts the phase current increment. With joint temperature increment The system completes the compression encoding of the sign and value bits, generating an 8B steady-state compressed differential frame containing the loop physical address, message type identifier, phase current difference quantization code, temperature difference quantization code, and cyclic redundancy check code. When the bus transceiver driver receives the polling token, it modulates it into a differential physical signal and sends it to the half-duplex RS485 communication bus. During the sensing and acquisition of insulation leakage current, the multi-parameter sensing and acquisition module installs high-permeability permalloy micro-current transformers at the grounding lead of each branch cable to sense the AC micro-current flowing through the grounding wire of the main insulation. The output of the current transformer is connected to a high-impedance differential instrumentation amplifier at the analog sampling front end to complete the current-to-voltage conversion and 100x amplification. The amplified signal is filtered by a 50Hz second-order active bandpass filter circuit to remove power frequency harmonics and high-frequency noise, and then input to a true RMS conversion chip to output a DC signal from 0V to 3.3V. The signal is then synchronously acquired by a 24-bit analog-to-digital converter at a sampling period of 200ms as the RMS value of the insulation leakage current with a range of 0mA to 50mA and a resolution of 10μA. This RMS value is then input to a differential quantization encoder as the load data for the complete frame of the transient event and the reference reset frame.

[0047] The differential quantization encoder internally incorporates a steady-state transmission accumulator counting unit. During the continuous generation of steady-state compressed differential frames, this counting unit increments its count in each sampling period. The count continues until it reaches a preset accumulation period limit of 50 polling cycles. At that time, the branch status sensing and telemetry transmission module assembles a reference reset frame within the currently allocated polling time slot. This frame contains the current RMS value of the full phase current, the junction temperature, the RMS value of the zero-sequence current, and the insulation leakage current, and sends it to the half-duplex RS485 communication bus. , , The reference storage item corresponding to the insulation leakage current is refreshed to the measured value at the current sampling time, all physical state parameters are reset to the new reference values ​​for subsequent differential calculations, and the accumulation counting unit is cleared and reset to prevent the unidirectional accumulation of nonlinear differential quantization truncation error; when the cable circuit changes state due to sudden load changes or joint heating... When the value is greater than 0.05, the differential quantization encoder switches to full encoding mode, packages and generates a complete transient event frame with a byte length of 32B, sets the emergency telemetry flag in the frame header control word, writes the collected full-phase current, zero-sequence current, joint temperature and insulation leakage current into the data load area, and updates the current sampled physical quantity into the reference value register as a new reference for subsequent differential judgment, maintaining the consistency of data parsing across the entire network under abnormal operating conditions.

[0048] The dual-priority transmission arbitration module of the link arbitration and timing control transmission module receives trip control commands from the remote master station through the uplink remote communication interface, sends an interrupt request signal to the bus time slot management module, and suspends the dynamic time-division polling sequence; the dual-priority transmission arbitration module inserts a protection time slot with a basic duration of 5ms at the end of the currently transmitted data frame on the half-duplex RS485 communication bus. During the protection time slot, the receiver enable pin of the bus transceiver chip continuously monitors the differential level idle state, and the physical layer hardware level comparison circuit continuously compares the voltage difference between the positive and negative terminals of the differential twisted pair. ,when When the voltage is not less than +200mV and there is no level transition pulse, the bus is determined to be at an idle bias level. After detecting a pulse spike caused by circuit breaker operation arc or external electromagnetic interference coupling, the level comparison circuit continuously monitors the pulse duration. When this duration exceeds the 5ms base duration of the protection time slot, the delay timer is triggered to restart, causing the protection time slot to extend after the pulse disappears until the bus differential level remains at the idle bias level for a preset silence duration of 1.5ms. Subsequently, the bus driver circuit broadcasts a preemptive control token frame with a byte length of 12B, utilizing the physical layer silence window to block... To prevent frame structure distortion induced by high-frequency electromagnetic noise, during the hardware switching process of the protection time slot, after the dual-priority transmission arbitration module captures the remote trip interrupt, the hardware byte counter of the serial port controller continuously tracks the data frame payload being received. When the end stop bit of the current message is received and the verification completion interrupt is triggered, the microprocessor hardware pin locks the transmit enable terminal of the bus transceiver driver to a low level, and freezes the timer count of the bus time slot management module for the next regular polling time slot, so that the bus enters a physical idle state with no data flow after the current slave data is received, and the switching of the protection time slot is completed at the frame boundary.

[0049] The control instruction parsing and verification module of the fee control response and status feedback closed-loop module receives the preemptive control token frame and extracts the target circuit physical address code, trip control function code 0x5A, rolling serial number, and 16-bit cyclic redundancy check code. When the physical address matches the local hardware DIP switch and the check code calculation is correct, a trigger enable signal is output to the microcontroller via a hardware interrupt. The microcontroller generates an 8B confirmation frame within a 2ms hardware response window and sends it to the half-duplex RS485 communication bus. Simultaneously, the power output circuit of the opening and closing timing drive module outputs a 50ms DC 24V trip drive pulse to drive the opening coil. After the circuit breaker mechanism operates, the local switch status feedback module detects the node change level through the opto-isolation circuit. The level corresponding to the circuit breaker auxiliary contact changes from 5V high level to 0V low level. At the same time, the phase current transformer sampling circuit detects that the effective value of the phase current drops below the 6.3A disconnection judgment threshold. When both the node change level and the phase current return to zero are satisfied... When the criteria are met, telemetry data confirming the successful tripping action is generated. After the link arbitration and timing control transmission module resumes bus polling, the fee control response and status feedback closed-loop module prioritizes sending the tripping action confirmation status frame in the first available polling time slot, completing the control command issuance, local mechanism action, electrical and physical disconnection, and remote signaling status feedback. In the first time slot after the bus polling is resumed, the bus time slot management module receives the local confirmation frame and forcibly resets the address of the first clock allocation slot in the polling sequence to the physical address of the target circuit that has already tripped. When the status perception and telemetry transmission modules of the remaining inactive branches detect that the bus time slot address is inconsistent with the local hardware address, they maintain a high impedance state for receiving. After the fee control response and status feedback closed-loop module of the target circuit captures the first frame token after the recovery, it directly skips the regular telemetry transmission queue, prioritizes loading the tripping action confirmation status frame into the bus driver, and sends it back. This allows the target circuit to occupy the first available polling time slot after the recovery in a single half-duplex master-slave architecture and avoids sending at the same time as other nodes.

[0050] Example 4: This example combines Figures 1 to 2 This paper describes a cable branch box status data telemetry system, such as... Figure 1As shown, the branch status sensing and telemetry transmission module collects operating electrical parameters and connector temperature, and sends steady-state compressed differential frames or transient event complete frames to the half-duplex RS485 communication bus according to the degree of state change. The half-duplex RS485 communication bus reports parameter data to the link arbitration and timing control transmission module. The link arbitration and timing control transmission module distributes polling tokens or broadcast preemptive control token frames to the half-duplex RS485 communication bus. During the distribution of polling tokens, the link arbitration and timing control transmission module responds to trip control commands, inserts protection time slots, detects differential levels, and extends protection time slots to empty slots. After the idle state, a preemptive control token frame is broadcast. The half-duplex RS485 communication bus sends a preemptive control token frame to the fee control response and status feedback closed-loop module. After the fee control response and status feedback closed-loop module verifies the token, it replies with an acknowledgment frame and outputs a tripping signal. It determines that the action is completed and sends a tripping action confirmation status frame to the half-duplex RS485 communication bus in the first time slot. The fee control response and status feedback closed-loop module replies with an acknowledgment frame and an action confirmation status frame to the half-duplex RS485 communication bus. The half-duplex RS485 communication bus sends an acknowledgment status frame back to the link arbitration and timing control transmission module.

[0051] like Figure 2 As shown, the multi-parameter sensor acquisition module is connected to the differential quantization encoder, which is connected to the bus transceiver driver. The multi-parameter sensor acquisition module transmits the acquired data to the differential quantization encoder, which encodes the received data and outputs it to the bus transceiver driver, which then performs the drive output.

[0052] Example 5: Before the cable branch box is put into operation on site, the branch status sensing and telemetry transmission module performs pre-baseline calibration on each branch circuit, collects the initial electrical parameters and ambient temperature under no-load conditions, and writes the initial phase current RMS value, the initial joint temperature value, and the initial zero-sequence current value into the internal memory of the differential quantization encoder as the state change degree. Calculated baseline value , and Rated parameters are set as follows A, ℃ and A; When the ambient thermal drift and power frequency micro-harmonics cause the sampling phase current to be 211.8A, the connector temperature to be 45.1℃, and the zero-sequence current to be 1.2A, corresponding to the reference values ​​of 210A, 45℃, and 1.2A at the previous update time, the calculation result of the differential quantization encoder is: The degree of state change is no greater than the preset steady-state disturbance threshold of 0.05. The differential quantization encoder maintains the differential compression process, generates 8B steady-state compressed differential frames and sends them to the half-duplex RS485 communication bus, so that the slight changes caused by sensor noise and ambient temperature drift continue to be transmitted according to the steady-state compressed differential frames. In the selection of weighting coefficients, the phase current directly reflects the load change and short-circuit transient, and its physical response time is on the order of milliseconds, so it is configured with a weight of 0.7; the joint temperature reflects the Joule heat accumulation caused by the deterioration of the contact resistance, and its heat conduction and temperature rise time constant is on the order of minutes. It is not sensitive to short-term fluctuations, but it can reflect long-term insulation deterioration, so it is configured with a weight of 0.2; the zero-sequence current is used to characterize the grounding asymmetric insulation fault at the 30A threshold, based on an auxiliary weight of 0.1. The sum of the three weights is 1, which is used to take into account the influence of fast electrical transients and slow heat accumulation on the degree of state change.

[0053] During the electrical parameter calibration process of the link arbitration and timing control transmission module accessing the half-duplex RS485 communication bus, the bus time slot management module targets the voltage difference between the positive and negative terminals of the differential twisted pair. The system sets an idle decision level of +200mV and a preset silence duration of 1.5ms, and continuously applies an idle bias level to the differential line. When an external switch action arc or electromagnetic surge induces a transient pulse voltage exceeding the +200mV threshold on the differential line, the level detection circuit detects the duration of the transient interference pulse. If its duration exceeds the basic duration... If the timeout reaches ms, the delay timer is triggered to restart and the protection time slot is extended forward until the bus is continuously in an idle bias state without pulse disturbance for a preset silence duration of 1.5ms. Subsequently, the dual-priority transmission arbitration module broadcasts a preemptive control token frame with a byte length of 12B. The total time for control command interaction is [not specified]. From basic protection time slot ms, instruction transmission time ms, hardware processing time 2ms and acknowledgment frame transmission time The total duration is 27.83ms. During the application of the idle bias level and the differential level idle listening process, the high-impedance passive voltage divider resistor network inside the bus time slot management module provides a fixed differential bias of +200mV to +260mV in the floating state when no node is transmitting on the bus. At this time, the driver of the bus transceiver chip remains in a high-impedance input state. The level detection circuit uses a high-speed differential window comparator, with the upper comparison threshold set to +350mV and the lower comparison threshold set to -100mV. When an external electromagnetic pulse is superimposed on the bus, causing a transient... When the differential voltage exceeds the window or polarity reversal occurs, the comparator outputs a pulse, and the level detection circuit continuously detects the duration of the transient interference pulse accordingly. When the duration exceeds the basic duration of 5ms, the delay timer restarts and the protection time slot is extended until the bus differential voltage continuously and stably falls back to the basic bias window of +200mV to +350mV and is maintained for 1.5ms. At this point, it is determined that the bus has returned to the idle bias state without pulse disturbance, so that the protection time slot extension process and the differential level idle monitoring are completed in the same circuit state.

[0054] Example 6: When multiple branch circuits in a cable branch box are under extreme unbalanced load and accompanied by sudden temperature rise caused by contact resistance degradation, the branch status sensing and telemetry transmission module synchronously acquires the effective value of the phase current of each circuit through an electromagnetically isolated analog sampling front-end and a high-precision analog-to-digital converter. Connector temperature With the effective value of zero-sequence current The differential quantization encoder combines the stored reference value from the previous update time. , and Calculate the degree of state change When the circuit phase current is maintained at 210A and the zero-sequence current is maintained at 1.2A, and the cable joint experiences abnormal contact resistance due to poor local contact, causing the joint temperature to suddenly increase from 45℃ to 75℃, the differential quantization encoder substitutes the circuit's rated operating current reference value. A. Rated temperature limit of the connector ℃, zero-sequence current alarm threshold A and weighting coefficients , and Complete the substitution operation for the following expression: The obtained state change degree The disturbance exceeds the preset steady-state disturbance threshold of 0.05. The differential quantization encoder de-suppresses steady-state differential compression and switches to full-quantization encoding mode, generating a complete 32B transient event frame. An emergency telemetry flag is set in the frame header, and the currently sampled physical quantity is updated to a new baseline value for subsequent differential calculations. In handling insulation degradation events, the differential quantization encoder sets up a hardware limit judgment channel for insulation leakage current while periodically calculating the degree of state change. When microscopic damage occurs to the main cable insulation, causing the effective value of the insulation leakage current to change abruptly by more than 5mA in a single period or its absolute value to exceed the 10mA alarm threshold, the differential quantization encoder bypasses the numerical judgment of the degree of state change, directly sets the emergency telemetry flag, and switches to full-quantization encoding mode. It then sends the complete 32B transient event frame, including the insulation leakage current, to the half-duplex RS485 communication bus, ensuring that the insulation leakage current is fully reported along with the abnormal state data.

[0055] When a strong electromagnetic surge causes data frame distortion or time slot timeout on the half-duplex RS485 communication bus, and the bus time slot management module of the link arbitration and timing control transmission module fails to receive a response frame from the corresponding branch status sensing and telemetry transmission module after three consecutive polls, it determines that the current polling time slot has timed out and skips the allocated time slot of that node, allowing the remaining loops to continue communicating according to the dynamic time-division polling sequence. The interfered node buffers the differential quantization increments that have not yet been sent in the local dynamic storage area. After the communication link is restored and the subsequent polling token is received, it prioritizes sending a reference reset frame containing full-phase current, joint temperature, zero-sequence current, and insulation leakage current in the current polling time slot. At the same time, it resets all physical state parameters in the reference reset frame to the new reference values ​​for subsequent differential calculations to correct the accumulated error during the channel interruption. During the remote trip control process, when the switch status local feedback module detects that the node change level and the phase current return to zero are in the process of remote trip control, the node will be automatically reset to the new reference value for subsequent differential calculations. When the timing fails to simultaneously meet the disconnection criteria, the fee control response and status feedback closed-loop module sends a tripping action confirmation status frame with the set abnormal alarm flag in the first available polling time slot after the bus resumes polling. The link arbitration and timing control transmission module transmits a failure-to-operate alarm back to the remote master station through the uplink remote communication interface and blocks the subsequent closing sequence. The disconnection judgment threshold is set to 6.3A, which is set according to 1% of the rated operating current base value of the 630A circuit, and is used to filter out the residual weak capacitive current generated by the distributed capacitance after the line is disconnected. For the case where the outgoing circuit is lightly loaded and the phase current before tripping is already lower than 6.3A, the switch status local feedback module simultaneously verifies that the node change level jumps from 5V to 0V, and verifies that the phase current drop after the tripping pulse is issued reaches more than 80% of the sampled value before tripping. Only when the node change level and the phase current return to zero jointly meet the disconnection criteria will the confirmation status telemetry data characterizing the successful tripping action be generated.

[0056] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A cable branch box status data telemetry system, characterized in that, include: Each branch status perception and telemetry transmission module, and each cost control response and status feedback closed-loop module are connected to the link arbitration and timing control transmission module via a half-duplex RS485 communication bus. The branch status sensing and telemetry transmission module is used to collect the operating electrical parameters and joint temperature of the corresponding cable branch circuit, determine the operating status based on the degree of status change, and send a steady-state compressed differential frame to the half-duplex RS485 communication bus when the degree of status change is not greater than the preset steady-state disturbance threshold, and send a complete transient event frame when the degree of status change is greater than the preset steady-state disturbance threshold. The link arbitration and timing control transmission module is used to distribute polling tokens on the half-duplex RS485 communication bus. In response to the remote trip control command, it inserts a protection time slot at the end of the current transmission data frame and suspends the polling timing. Differential level idle detection is performed within the protection time slot. When a disturbance pulse is detected, the protection time slot is extended until the bus level is continuously at the idle bias level to reach the preset silence maintenance time. Then, a preemptive control token frame is broadcast. The fee control response and status feedback closed-loop module is used to reply with an acknowledgment frame to the half-duplex RS485 communication bus after the verification of the preemptive control token frame passes, output the tripping signal, determine the completion of the tripping action based on the node change level and the phase current returning to zero, and send the tripping action confirmation status frame to the link arbitration and timing control transmission module in the first time slot after the bus resumes polling.

2. The cable branch box status data telemetry system according to claim 1, characterized in that, Degree of state change The following formula is used to calculate: ,in, , , The corresponding cable branch circuits are in the 1st The effective values ​​of phase current, junction temperature and zero-sequence current were collected at each sampling time. , , These are the baseline values ​​corresponding to the previous update time; This is the reference value for the rated operating current of the circuit. This is the rated temperature limit reference value for the connector. This is the zero-sequence current alarm threshold value; , , The weighting coefficients are dimensionless and satisfy the following conditions: ; The sampling period.

3. The cable branch box status data telemetry system according to claim 2, characterized in that, The preset steady-state disturbance threshold ranges from 0.03 to 0.08; when the degree of state change is not greater than the preset steady-state disturbance threshold, the branch state perception and telemetry transmission module maintains the baseline value of the previous update time unchanged. When the degree of state change exceeds the preset steady-state disturbance threshold, the branch state sensing and telemetry transmission module updates the effective value of phase current, junction temperature and effective value of zero-sequence current collected at the current sampling time to the reference value for the next cycle.

4. The cable branch box status data telemetry system according to claim 3, characterized in that, When the cumulative number of consecutive transmissions of steady-state compressed differential frames by the branch state perception and telemetry transmission module reaches the preset cumulative period limit, it sends a reference reset frame containing all physical state parameters to the half-duplex RS485 communication bus within the current polling time slot, and resets all physical state parameters to the new reference value for subsequent differential calculations; wherein, the preset cumulative period limit is 30 to 80 polling periods.

5. The cable branch box status data telemetry system according to claim 1, characterized in that, The length of the steady-state compressed differential frame is 6B to 10B, and the frame contains quantized encoded data of the phase current difference and the junction temperature difference; the length of the transient event complete frame is 28B to 36B, the frame header contains an emergency telemetry flag, and the frame body contains the RMS value of the full-phase current, the junction temperature, the RMS value of the zero-sequence current, and the insulation leakage current.

6. The cable branch box status data telemetry system according to claim 1, characterized in that, The branch state perception and telemetry transmission module includes a multi-parameter sensing and acquisition module, a differential quantization encoder, and a bus transceiver driver. The multi-parameter sensing and acquisition module is connected to the cable branch loop and is used to synchronously acquire analog sensing signals and convert them into operating electrical parameters and connector temperatures. The differential quantization encoder is connected to the multi-parameter sensing and acquisition module and is used to encode discrete physical quantities according to the degree of state change to generate corresponding data frames in steady-state compressed differential frames and transient event complete frames. The bus transceiver driver is connected to the differential quantization encoder and the half-duplex RS485 communication bus to modulate the encoded data frame into a differential physical signal in response to the bus polling token.

7. The cable branch box status data telemetry system according to claim 1, characterized in that, The link arbitration and timing control transmission module includes a bus time slot management module, a dual-priority transmission arbitration module, and an uplink remote communication interface; The bus time slot management module is used to build a dynamic time-division polling sequence on the half-duplex RS485 communication bus and issue polling tokens to each branch status perception and telemetry transmission module in sequence according to the preset time slot allocation table. The dual-priority transmission arbitration module is connected to the bus time slot management module and the uplink remote communication interface. It is used to insert a protection time slot when a remote trip control command is received, and to control the bus time slot management module to interrupt the current polling sequence. The uplink remote communication interface is used to establish a communication link with the remote master station.

8. The cable branch box status data telemetry system according to claim 1, characterized in that, The basic duration of the protection time slot is 3.00ms to 8.00ms. The link arbitration and timing control transmission module continuously applies an idle bias level to the half-duplex RS485 communication bus within the protection time slot. If the duration of the transient interference pulse on the differential line exceeds the basic duration, the protection time slot will be extended until the bus is continuously in an idle bias state without pulse disturbance to reach the preset silent maintenance time.

9. The cable branch box status data telemetry system according to claim 1, characterized in that, The fee control response and status feedback closed-loop module includes a control command parsing and verification module, a tripping and closing timing drive module, and a switch status local feedback module. The control command parsing and verification module is used to parse the target circuit physical address code, control function code, and cyclic redundancy check code in the preemptive control token frame, and outputs a trigger enable signal when the physical address matches and the verification passes. The tripping and closing timing drive module is connected to the control command parsing and verification module and is used to output a tripping pulse to the switch node tripping circuit in response to the trigger enable signal.

10. A cable branch box status data telemetry system according to claim 9, characterized in that, The local feedback module for switch status is connected to the auxiliary contact of the switch node and the current transformer for acquiring the phase current of the circuit. When a change in the level of the auxiliary contact is detected and the effective value of the phase current of the circuit falls below the disconnection judgment threshold, telemetry data confirming the successful tripping action is generated. After the link arbitration and timing control transmission module resumes bus polling, the fee control response and status feedback closed-loop module prioritizes sending the tripping action confirmation status frame in the first available polling time slot.

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