Merging unit for metering and metering system

Abstract

The invention discloses a merging unit for metering and a metering system, and relates to the technical field of electric power metering, the merging unit for metering comprises a cabinet provided with a plurality of slots for accessing metering board cards, a main control board arranged in the cabinet, and at least one metering board card; a hot plug connector is correspondingly connected in the case and corresponds to each slot; the main control board is respectively connected with the plurality of hot plug connectors and is used for detecting the in-place state of the board card of each slot and executing initialization operation or removal operation according to the in-place state of the board card; the metering board card and the slot are arranged in a pluggable manner; the hot plug connector is provided with a plurality of pins with different lengths, the pin with the longest length is a grounding pin, and when the metering board card is connected into the slot, the metering board card establishes an electric connection path with the main control board through the plurality of pins; and the metering board card is used for receiving the analog signal, processing the analog signal and outputting the processed analog signal to the main control board through a plurality of pins. The invention aims to improve the precision, the reliability and the operation and maintenance efficiency of the merging unit for metering.

Description

Technical Field

[0001] This invention relates to the field of power metering technology, and in particular to a metering merging unit and metering system. Background Technology

[0002] In the construction of smart substations and digital power grids, the merging unit (MU) for metering, as the core equipment of the process layer, undertakes the critical task of synchronously acquiring, digitizing, and transmitting the analog signals output from electronic instrument transformers to the bay and station control layers according to standard protocols (such as IEC 61850-9-2LE). It is the data source for achieving accurate power metering, status monitoring, and intelligent control. However, existing merging units generally adopt an integrated architecture where metering, protection, and measurement and control functions share a common front-end sampling channel. This makes the metering circuit susceptible to interference from large dynamic signals and switching noise in the protection or measurement and control circuits, making it difficult to meet the stringent requirements of high-precision metering in power trading. More importantly, traditional merging units lack modularity and independent operation and maintenance capabilities. When the metering function needs calibration, upgrade, or malfunction, the entire unit must be powered off and shut down, which not only interrupts the continuity of critical services such as protection and measurement and control but also significantly reduces operation and maintenance efficiency. Summary of the Invention

[0003] The main objective of this invention is to propose a metering merging unit and metering system, which aims to improve the accuracy, reliability and operation and maintenance efficiency of the metering merging unit.

[0004] To achieve the above objectives, the present invention proposes a metering merging unit, the metering merging unit comprising: The chassis has multiple slots for connecting metering boards, and a hot-swappable connector is connected to each slot inside the chassis. The main control board is located inside the chassis and is electrically connected to multiple hot-swappable connectors. The main control board is used to communicate with external devices and to detect the board presence status of each slot, and to perform initialization or removal operations according to the board presence status. At least one metering board, wherein the metering board is pluggably configured to be inserted into the slot; The hot-swappable connector has multiple pins of different lengths, and the longest pin among the multiple pins is the ground pin. When the metering board is connected to the slot, the metering board establishes an electrical connection path with the main control board through the multiple pins. The metering board is used to receive analog signals output by external sensors, process the analog signals, and output them to the main control board through multiple pins on the hot-swappable connector.

[0005] In one embodiment, the metering board includes: Input interface, used to receive analog signals output from external sensors; A signal conditioning circuit is electrically connected to the input interface. The signal conditioning circuit is used to receive the analog signal, perform signal preprocessing on the analog signal, and output a corresponding preprocessed signal. An analog-to-digital converter (ADC) is electrically connected to the signal conditioning circuit. The ADC is used to convert the preprocessed signal into a digital signal and output the corresponding digital signal. A signal processing unit is electrically connected to the analog-to-digital converter; The signal processing unit is used to control the sampling timing of the analog-to-digital converter, perform error compensation processing on the digital signal, and encapsulate the error-compensated digital signal into a digital message according to a preset protocol and output it to the main control board through multiple pins on the hot-swappable connector.

[0006] In one embodiment, the signal processing unit includes: A clock synchronization module is used to receive an external pulse reference signal, process the pulse reference signal, and output a corresponding local sampling clock signal. A sampling control module is electrically connected to the clock synchronization module. The sampling control module is used to output a corresponding sampling control signal to the analog-to-digital converter according to the local sampling clock signal, so as to control the sampling timing of the analog-to-digital converter. An error compensation module is electrically connected to the analog-to-digital converter. The error compensation module is used to receive external correction parameters and perform error compensation processing on the digital signal according to the external correction parameters. The message framing module is electrically connected to the error compensation module. The message framing module is used to encapsulate the error-compensated digital signal into a digital message according to a preset protocol and then output it to the main control board.

[0007] In one embodiment, the signal processing unit further includes: The self-test control module is electrically connected to the analog-to-digital converter and the error compensation module, respectively. A switching circuit is provided, wherein a first input terminal of the switching circuit is used to connect an external sensor, a second input terminal of the switching circuit is used to connect an internal reference voltage, and an output terminal of the switching circuit is electrically connected to the input terminal of the analog-to-digital converter. The switching circuit is used to connect the electrical connection between the first input terminal and the output terminal or to connect the electrical connection between the second input terminal and the output terminal. The analog-to-digital converter is used to sample the internal reference voltage and output a corresponding sampling signal to the self-test control module when the switching circuit connects the second input terminal and the output terminal. The self-test control module is used to compare the sampled signal with the preset sampled value and output the corresponding error comparison result to the error compensation module, so that the error compensation module can perform error compensation processing on the digital signal according to the external correction parameters and the error comparison result.

[0008] In one embodiment, the metering board further includes: A storage module is electrically connected to the signal processing unit, and the storage module is used to store at least one of the metering board's identity information, production information, and external correction parameters.

[0009] In one embodiment, the metering board further includes: A digital temperature sensor is electrically connected to the signal processing unit; The digital temperature sensor is used to detect the temperature of the metering board and output the corresponding temperature detection signal to the signal processing unit.

[0010] In one embodiment, the metering merging unit further includes a status indicator light, which is electrically connected to the main control board. The main control board is used to control the status indicator light to work / stop working based on the board's in-situ status.

[0011] In one embodiment, the metering merging unit further includes a communication bus, and the main control board and the metering board are communicatively connected via the communication bus; The main control board is used to detect the board presence status of each slot through the communication bus, and to perform initialization or removal operations according to the board presence status.

[0012] In one embodiment, the metering merging unit further includes: A reference voltage source, which is electrically connected to the metering board; The reference voltage source is used to provide an internal reference voltage to the metering board.

[0013] The present invention also proposes a metering system, which includes a metering merging unit as described in any one of the above claims, and external devices; The external device is communicatively connected to the main control board of the metering merging unit. The external device is used to send external correction parameters to the main control board when it receives an external trigger signal, so that the main control board outputs the external correction parameters to the metering board.

[0014] In practical applications, the metering merging unit, through its modular hardware architecture and hot-swappable independent metering circuit design, enables online replacement, calibration, or upgrades of metering boards without requiring system downtime. This ensures the normal operation of other critical functions while reducing maintenance costs and the risk of power outages. Furthermore, the metering boards interface with the main control board via hot-swappable connectors, with pins designed in a length-based hierarchy, enabling safe power-on timing control during insertion and removal, effectively mitigating issues such as arcing, signal disturbances, and device damage. This enhances the accuracy, reliability, and maintenance efficiency of the metering merging unit. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a module of an embodiment of the metering merging unit of the present invention; Figure 2 This is a schematic diagram of another embodiment of the metering merging unit of the present invention; Figure 3 This is a schematic diagram of another embodiment of the metering merging unit of the present invention; Figure 4 This is a schematic diagram of another embodiment of the metering merging unit of the present invention; Figure 5 This is a schematic diagram of another embodiment of the metering merging unit of the present invention; Figure 6 This is a schematic diagram of another embodiment of the metering merging unit of the present invention; Figure 7 This is a schematic diagram of another embodiment of the metering merging unit of the present invention; Figure 8 This is a schematic diagram illustrating the inspection principle of an embodiment of the metrology system of the present invention.

[0017] Explanation of icon numbers: 10. Chassis; 20. Slot; 30. Main control board; 40. Metering board; 50. Status indicator light; 60. Reference voltage source; 41. Input interface; 42. Signal conditioning circuit; 43. Analog-to-digital converter; 44. Signal processing unit; 45. Storage module; 46. Digital temperature sensor; 01. Clock synchronization module; 02. Sampling control module; 03. Error compensation module; 04. Message framing module; 05. Self-test control module; 06. Switching circuit.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] In the construction of smart substations and digital power grids, the merging unit (MU) for metering, as the core equipment of the process layer, undertakes the critical task of synchronously acquiring, digitizing, and transmitting the analog signals output from electronic instrument transformers to the bay and station control layers according to standard protocols (such as IEC 61850-9-2LE). It is the data source for achieving accurate power metering, status monitoring, and intelligent control. However, existing merging units generally adopt an integrated architecture where metering, protection, and measurement and control functions share a common front-end sampling channel. This makes the metering circuit susceptible to interference from large dynamic signals and switching noise in the protection or measurement and control circuits, making it difficult to meet the stringent requirements of high-precision metering in power trading. More importantly, traditional merging units lack modularity and independent operation and maintenance capabilities. When the metering function needs calibration, upgrade, or malfunction, the entire unit must be powered off and shut down, which not only interrupts the continuity of critical services such as protection and measurement and control but also significantly reduces operation and maintenance efficiency.

[0021] Therefore, refer to Figure 1 The present invention proposes a metering merging unit, the metering merging unit comprising: The chassis 10 is provided with a plurality of slots 20 for connecting the metering board 40, and a hot-swappable connector is connected to each of the slots 20 inside the chassis 10. The main control board 30 is disposed inside the chassis 10, and the main control board 30 is electrically connected to a plurality of hot-swappable connectors respectively. The main control board 30 is used to communicate with external devices and to detect the board presence status of each slot 20, and to perform initialization or removal operations according to the board presence status. At least one metering board 40, wherein the metering board 40 is pluggably configured to be inserted into the slot 20; The hot-swappable connector has multiple pins of different lengths, and the longest pin among the multiple pins is the ground pin. When the metering board 40 is connected to the slot 20, the metering board 40 establishes an electrical connection path with the main control board 30 through the multiple pins. The metering board 40 is used to receive analog signals output by external sensors, process the analog signals, and output them to the main control board 30 through multiple pins on the hot-swappable connector.

[0022] In this embodiment, the main control board 30 can be implemented using a main controller, such as an MCU, DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), PLC, or SOC (System On Chip).

[0023] In this embodiment, the metering merging unit adopts a highly modular hardware architecture, including a chassis 10, a main control board 30 responsible for general communication and protocol processing, and multiple hot-swappable metering boards 40. The main control board 30 is located inside the chassis 10. Each slot 20 on the chassis 10 can be configured with a high-reliability connector socket conforming to CPCI or VPX standards for board-to-board docking with the metering boards 40. Optionally, the metering merging unit can use a standard 19-inch chassis 10, with an interface panel at the rear and the slot 20 area for the metering boards 40 at the front.

[0024] In this embodiment, the main control board 30 can be fixed in the middle of the chassis 10, providing external communication interfaces, including an electrical Ethernet port for communication with a host computer, two pairs of optical Ethernet ports for outputting 9-2 messages, and a clock synchronization signal input / output interface. Hot-swappable metering boards 40 are inserted into dedicated slots 20 located at the front of the chassis 10 via board guide rails. Slots 20 must be matched with high-reliability connectors conforming to CPCI or VPX standards, ensuring good contact and supporting hot-swapping functionality during use.

[0025] In this embodiment, the metering board 40 supports online hot-swapping. The pins of the hot-swappable connector are arranged in a graded manner according to length, with the ground pin being the longest to ensure that the ground wire is contacted first and disconnected last. The power pins are of different lengths to achieve special sequencing such as power-on timing control. Optionally, the length of the signal pin is shorter than the length of the power pin, ensuring that during the insertion of the metering board 40 into the slot 20, the ground wire is contacted first, followed by power-on, and the signal is connected last; during removal, the signal is disconnected first, followed by power-on, and the ground wire is disconnected last, effectively improving the problem of arcing or logic disorder during insertion and removal.

[0026] In this embodiment, the main control board 30 monitors the card availability status of each slot 20 in real time. When a new metering card 40 is detected being inserted, the main control board 30 automatically powers it on, reads the identification information (including unique serial number, production batch, last calibration date, etc.) from the card's EEPROM, and performs initialization operations. When a card is detected being removed, the main control board 30 immediately performs a removal operation, removing it from the list of valid devices and recording an event log, effectively ensuring the real-time performance and effectiveness of hot-swapping of the metering card 40. In a redundant configuration, if a metering card 40 is removed, it can automatically switch to another normally functioning card, ensuring uninterrupted data flow and continuous operation of the device. When a metering card 40 needs to be upgraded, calibrated, or malfunctions, maintenance personnel can directly remove the old card and insert the new card at the operating site. During the entire process, other functions of the merging unit continue to operate normally, improving system availability and maintenance efficiency. It should be noted that each metering card 40 has a built-in EEPROM, which stores identification codes such as card identification information and calibration information. The host computer software can automatically identify the information of the inserted board through the main control board 30, including the production batch and the last calibration date, which facilitates asset management and metrological traceability.

[0027] During normal operation, the secondary analog signals from external sensors (such as current / voltage transformers) are directly connected to the independent analog front end of the metering board 40, without sharing any sampling channels with protection or control circuits, thus reducing interference from other circuits on metering accuracy. The metering board 40 processes the analog signals and outputs them to the main control board 30 via multiple pins on the hot-swappable connector. After being aggregated by the main control board 30, these signals can be output to the energy metering or control devices in the bay layer via an optical Ethernet port, providing high-precision, high-synchronization, and high-reliability data support for energy metering and other functions. Because the metering circuit is independent of protection and other safety circuits, professionals in power metering can independently calibrate and test the metering board 40 without affecting the functionality of the protection system.

[0028] Understandably, because the metering board 40 supports online hot-swapping, the metering circuit is physically isolated from other circuits, and its functions are independent, if a metering board 40 needs calibration, upgrade, or replacement, maintenance personnel can directly remove the old board and insert the new board while the system is powered on. The entire process requires no downtime, and other functions of the merging unit (such as data transmission protection) can continue to operate normally. This improves maintenance efficiency.

[0029] In practical applications, the metering merging unit, through its modular hardware architecture and hot-swappable independent metering circuit design, enables online replacement, calibration, or upgrades of the metering board 40 without requiring system downtime. This ensures the normal operation of other critical functions while reducing maintenance costs and the risk of power outages. Furthermore, the metering board 40 interfaces with the main control board 30 via a hot-swappable connector. Its pins are designed with length-based hierarchical structures, enabling safe power-on timing control during insertion and removal, effectively mitigating issues such as arcing, signal disturbances, or device damage. This enhances the accuracy, reliability, and maintenance efficiency of the metering merging unit.

[0030] In another embodiment, reference Figure 2 The metering board 40 includes: Input interface 41 is used to receive analog signals output from external sensors; The signal conditioning circuit 42 is electrically connected to the input interface 41. The signal conditioning circuit 42 is used to receive the analog signal, perform signal preprocessing on the analog signal, and output a corresponding preprocessed signal. An analog-to-digital converter 43 is electrically connected to the signal conditioning circuit 42. The analog-to-digital converter 43 is used to convert the preprocessed signal into an analog-to-digital signal and output the corresponding digital signal. Signal processing unit 44, which is electrically connected to analog-to-digital converter 43; The signal processing unit 44 is used to control the sampling timing of the analog-to-digital converter 43, perform error compensation processing on the digital signal, and encapsulate the error-compensated digital signal into a digital message according to a preset protocol and output it to the main control board 30 through multiple pins on the hot-swappable connector.

[0031] In this embodiment, the input interface 41 is used to directly receive the secondary analog signal output from an external electronic current transformer, wherein the secondary analog signal can be a current signal and / or a voltage signal. The signal conditioning circuit 42 is used to preprocess the original analog signal received through the input interface 41 to adapt it to the input range of the subsequent analog-to-digital converter 43 and reduce interference. Optionally, the signal conditioning circuit 42 can employ a high-precision, low-drift operational amplifier to perform anti-aliasing filtering and effective level adjustment on the analog signal from the current transformer. Anti-aliasing filtering is achieved by using a low-pass filter to filter out high-frequency noise above the Nyquist frequency (e.g., 2 kHz, corresponding to a 4 kHz sampling rate) to prevent aliasing distortion; level adjustment is achieved by scaling the large signal output from the current transformer (e.g., 100 V) to the input range supported by the ADC (e.g., ±2.5 V). The analog-to-digital converter 43 can employ a 24-bit high-precision Σ-Δ ADC chip, supporting multi-channel synchronous operation, possessing extremely high signal-to-noise ratio and integral nonlinearity. It also supports various high-precision clock synchronization signals such as IRIG-B and PPS, and utilizes advanced phase-locked loop technology to ensure the accuracy of sampling timing, controlling synchronization errors within microseconds to meet the requirements of time synchronization, timekeeping, and message dispersion. The sampling rate can be configured to 4kHz or 12.8kHz by the signal processing unit 44. The signal processing unit 44 can be implemented using the aforementioned main controller; in this embodiment, an FPGA chip is selected for the signal processing unit 44. The signal processing unit 44 can generate precise ADC sampling timing control signals (based on the local sampling clock output by the DPLL) to control the sampling timing of the analog-to-digital converter 43. It can also perform error compensation processing on digital signals, such as digital filtering, temperature drift compensation, and ratio / angle difference correction processing on the original digital signal output by the ADC, as well as running interpolation algorithms to align sampling times and ensure full station synchronization accuracy; in addition, the signal processing unit 44 can also encapsulate the compensated sampling data into digital messages according to a preset protocol, for example, the preset protocol is the IEC 61850-9-2LE protocol, which can be encapsulated into a fixed 286-byte digital sampling value message; and transmit the message to the main control board 30 through the signal pins of the hot-swappable connector.

[0032] Optionally, refer to Figure 6 The metering board 40 further includes: The digital temperature sensor 46 is electrically connected to the signal processing unit 44; The digital temperature sensor 46 is used to detect the temperature of the metering board 40 and output the corresponding temperature detection signal to the signal processing unit 44.

[0033] In this embodiment, the digital temperature sensor 46 is used to monitor the temperature changes in key areas of the board in real time. The digital temperature sensor 46 can be a high-precision TMP117 digital temperature sensor. Optionally, the TMP117 can be directly soldered onto the PCB, adjacent to the analog-to-digital converter 43, to accurately capture the core temperature rise during ADC operation. The corresponding temperature detection signal is then sent to the signal processing unit 44 for use in the temperature compensation algorithm.

[0034] Optionally, refer to Figure 5 The metering board 40 further includes: Storage module 45 is electrically connected to signal processing unit 44. Storage module 45 is used to store at least one of the identity information, production information and external correction parameters of metering board 40.

[0035] In this embodiment, the storage module 45 can be implemented using Flash memory, EEPROM (Electrically Erasable Programmable Read-Only Memory), etc. The storage module 45 is used to non-volatilely store key configuration and identity data, and must meet requirements such as no data loss upon power failure, reliable read / write operation, long lifespan, and small size. To this end, an EEPROM chip can be configured on the metering board 40 to store board identity information, such as board ID, production information (e.g., production batch, manufacturing date), and external correction parameters (including calibration coefficients and temperature compensation parameters). The calibration coefficients may include the ratio error correction coefficient and angle error correction value measured by a high-precision calibrator, and the temperature compensation parameters include temperature-error mapping model parameters (e.g., polynomial coefficients or lookup table data) for real-time temperature drift compensation by the FPGA. In addition, the storage module 45 can also record traceability information such as the last calibration time, calibration agency code, and standard number, so that the metrology merging unit can support metrological traceability and compliance, as well as store system operation status data, such as recording self-test history, hot-plug events, and timeliness performance statistics, thereby helping to diagnose faults and predictive maintenance.

[0036] In actual operation, after the metering board 40 completes a field calibration, maintenance personnel can send the new correction value to the merging unit via a host computer. The main control board 30 forwards this to the FPGA of the corresponding metering board 40. After verifying the data validity, the FPGA writes it to the designated address in the EEPROM. Subsequently, the FPGA automatically loads the latest parameters during each sampling process, ensuring that the output data is always based on the current optimal calibration state. In this way, by integrating the storage module 45 on the metering board 40, the merging unit for metering is identifiable, configurable, traceable, and updatable, improving the reliability of the merging unit's operation.

[0037] In one embodiment, reference Figure 3 The signal processing unit 44 includes: Clock synchronization module 01, which is used to receive an external pulse reference signal, process the pulse reference signal and output a corresponding local sampling clock signal; The sampling control module 02 is electrically connected to the clock synchronization module 01. The sampling control module 02 is used to output a corresponding sampling control signal to the analog-to-digital converter 43 according to the local sampling clock signal, so as to control the sampling timing of the analog-to-digital converter 43. Error compensation module 03 is electrically connected to analog-to-digital converter 43. Error compensation module 03 is used to receive external correction parameters and perform error compensation processing on the digital signal according to the external correction parameters. The message framing module 04 is electrically connected to the error compensation module 03. The message framing module 04 is used to encapsulate the digital signal after error compensation processing into a digital message according to a preset protocol and then output it to the main control board 30.

[0038] In this embodiment, the external pulse reference signal can be sent by the user to the main control board 30 via a host computer, and then sent to the clock synchronization module 01 via the main control board 30. Alternatively, it can be pre-stored in the storage module 45 by the R&D personnel, and then retrieved by the main control board 30 from the storage module 45 and sent to the clock synchronization module 01. Optionally, the clock synchronization module 01 can have a built-in high-precision digital phase-locked loop (DPLL) to perform phase detection, filtering, and tracking on the input pulse reference signal, generating a low-jitter, high-stability local sampling clock signal to ensure that the timing error is no greater than ±4µs.

[0039] In this embodiment, the sampling control module 02 receives the local sampling clock signal output by the clock synchronization module 01 and generates a precise ADC sampling control signal (such as CONVST or DRDY enable pulse) accordingly to ensure that the analog-to-digital converter 43 starts conversion at a fixed phase point in each sampling cycle, thereby realizing synchronous sampling of multi-channel voltage / current signals.

[0040] In this embodiment, the error compensation module 03 is electrically connected to the output of the analog-to-digital converter 43, receiving the raw digital sampled values ​​in real time. The error compensation module 03 can directly read pre-stored external correction parameters from the onboard EEPROM, including but not limited to ratio error correction coefficients and phase error correction values. Combined with the core temperature of the board collected by the digital temperature sensor 46, it dynamically calculates the gain error and zero-point offset compensation amount at the current temperature to correct the raw sampled values ​​(digital signals) output by the analog-to-digital converter 43. Optionally, the compensation algorithm can employ polynomial fitting or a lookup table method. This effectively improves the accuracy drift problem caused by device aging and changes in ambient temperature, ensuring that the merging unit maintains a measurement accuracy of 0.2S throughout its entire lifespan.

[0041] Optionally, the message framing module 04 is responsible for encapsulating the sampled values ​​of voltage, current, etc., and device status information after compensation by the error compensation module 03 into digital sampled value messages according to the IEC 61850-9-2LE standard. Optionally, each message frame has a fixed length of 286 bytes and includes the following key fields: sampling counter (SmpCnt): 0~3999 cyclic count, used for packet loss detection at the receiving end; synchronization status word (SmpSynch): indicating "synchronization", "out of synchronization", or "timekeeping" status; channel validity flag, quality bit, rated value identifier, etc. After the message framing module 04 completes the framing, the message can be sent to the main control board 30 via the signal pin of the hot-swappable connector, and then forwarded by the main control board 30 to the energy meter or measurement and control device in the interval layer via the optical Ethernet port.

[0042] It should be noted that for intelligent substations with high maintenance requirements and complex equipment, there are significant limitations and defects. Sensors and testing and monitoring devices need to be installed, which is complicated to install and wire, and the cost is relatively high. They also lack real-time self-monitoring capabilities, which can easily lead to delayed fault detection and low operation and maintenance efficiency.

[0043] refer to Figure 4 The signal processing unit 44 further includes: The self-test control module 05 is electrically connected to the analog-to-digital converter 43 and the error compensation module 03, respectively. The switching circuit 06 has a first input terminal for connecting an external sensor, a second input terminal for connecting an internal reference voltage, and an output terminal electrically connected to the input terminal of the analog-to-digital converter 43. The switching circuit 06 is used to connect the first input terminal and the output terminal or to connect the second input terminal and the output terminal. The analog-to-digital converter 43 is used to sample the internal reference voltage and output the corresponding sampling signal to the self-test control module 05 when the switching circuit 06 conducts the electrical connection between the second input terminal and the output terminal. The self-test control module 05 is used to compare the sampled signal with the preset sampled value and output the corresponding error comparison result to the error compensation module 03, so that the error compensation module 03 performs error compensation processing on the digital signal according to the external correction parameters and the error comparison result.

[0044] In this embodiment, the self-test control module 05 can automatically initiate a self-test process at a preset frequency (e.g., every 15 minutes). The self-test control module 05 can act as the main controller, outputting control signals to the switching circuit 06 to disconnect the external signal and connect the second input terminal, switching the ADC input from the external sensor signal to the internal reference voltage. The ADC samples the reference voltage multiple times (e.g., 100 times) and takes the average value as the measured sample value. The self-test control module 05 can have a comparison circuit inside to compare the measured sample value with the preset sample value (theoretical value) and output the corresponding error comparison result, thereby achieving cyclic self-testing. It should be noted that the error comparison result can include zero-point offset and gain error values. The self-test control module 05 sends the calculated offset and gain error values ​​as real-time compensation parameters to the error compensation module 03. Thus, the error compensation module 03 can combine external correction parameters and real-time compensation parameters to perform error compensation. After the self-test is completed, the self-test control module 05 controls the switching circuit 06 to switch back to the external sensor input, continuing the normal measurement process. Meanwhile, the self-test control module 05 can read the real-time temperature value of the TMP117 temperature sensor and, combined with historical self-test data, dynamically update the "error-temperature" mathematical model (such as third-order polynomial coefficients) to achieve temperature adaptive compensation.

[0045] It should be noted that maintenance personnel can also perform the following operations through host computer software (such as the "Verification Configuration" tab in the LabVIEW interface): remotely issue high-precision correction values: after on-site calibration using a 0.05-level calibrator (such as XL-805A), write the better ratio and angle difference correction coefficients into the EEPROM of the metering board 40; query self-test history: such as reading the zero drift, gain error and corresponding temperature of the last 10 self-tests; force trigger self-test: manually start the self-test process for fault diagnosis; automatic maintenance of CC value: the FPGA periodically (such as daily) calculates and updates the channel characteristic (CC value) coefficient based on the self-test results to ensure the long-term stability of the measurement link.

[0046] Optionally, refer to Figure 4The metering merging unit further includes: Reference voltage source 60, which is electrically connected to the metering board 40; The reference voltage source 60 is used to provide an internal reference voltage to the metering board 40.

[0047] In this embodiment, each metering board 40 in the metering merging unit can integrate a high-precision reference voltage source 60 chip. The reference voltage source 60 chip is directly connected to the analog-to-digital converter 43 (ADC) on the metering board 40 through PCB traces, and is also connected to the second input terminal of the switching circuit 06 (such as an analog multiplexer) as an internal self-test signal source.

[0048] In this embodiment, the reference voltage source 60 can operate in normal metering mode and self-test mode. In normal metering mode, the reference voltage source 60 does not participate in external signal acquisition, but its output can be used as an internal reference for the ADC or for bias calibration (depending on the ADC architecture) to improve overall linearity. In self-test mode, every 15 minutes, the FPGA in the metering board 40 controls the switching circuit 06 to switch the ADC input from the external transformer signal to the output of the reference voltage source 60. The ADC samples the reference voltage to obtain the measured sample value. The FPGA compares this value with the theoretical expected value (calculated based on the ADC full scale and gain) and calculates error parameters such as zero-point drift and gain error. The error parameters are sent to the error compensation module 03 for real-time correction of subsequent sampling results of external power grid signals. At the same time, combined with the core temperature of the board read by the temperature sensor, the FPGA can dynamically update the "error-temperature" compensation model, effectively improving the accuracy drift problem caused by device aging or environmental changes.

[0049] In practical applications, the metering merging unit proposed in this application has an error self-monitoring function to improve a series of problems such as the measurement accuracy of traditional merging units often being affected by interference due to the lack of effective monitoring, inconvenient operation and maintenance, and lack of real-time self-diagnostic capabilities. It eliminates the need for external sensors or testing devices, saving installation costs and wiring complexity; faults are detected promptly, avoiding measurement inaccuracies caused by zero drift or gain degradation; furthermore, it supports live self-testing and remote calibration, improving operation and maintenance efficiency.

[0050] Optionally, refer to Figure 7 The metering merging unit also includes a status indicator light 50, which is electrically connected to the main control board 30. The main control board 30 is used to control the status indicator light 50 to work / stop working according to the board's in-place status.

[0051] In this embodiment, the status indicator light 50 can be disposed on the front panel of the chassis 10. The status indicator light 50 can include various types, including but not limited to power indicator light, running indicator light, and fault indicator light. All status indicator lights 50 need to be electrically connected to the main control board 30. The main control board 30 has built-in status monitoring logic, which can collect the board presence signal, power enable status, FPGA heartbeat signal, and self-test results of each slot 20 in real time, and dynamically control the on / off or flashing mode of the corresponding indicator light accordingly.

[0052] Optionally, each metering board 40 slot 20 can be equipped with three independent status indicator lights 50. For example, when maintenance personnel insert a new metering board 40 into the corresponding slot 20: firstly, the power indicator light of the slot 20 immediately lights up, indicating that power supply has been established; after about 2 seconds, if the FPGA completes startup and begins sending heartbeats, the operation indicator light begins to flash slowly; if the board's internal self-test detects that the ADC gain error exceeds the limit, it will actively report a fault code, and the main control board 30 will then light up the fault indicator light, prompting the staff to further calibrate or replace the board. In addition, the main control board 30 can also synchronously upload the status of each indicator light to the host computer software, displaying it in the form of virtual LEDs in the graphical interface, thus achieving consistency between local and remote status.

[0053] The inclusion of status indicator light 50 enhances the observability and maintainability of the metering merging unit. Maintenance personnel can perform the following operations without opening chassis 10 or connecting debugging tools: quickly confirming whether the boards are installed correctly, determining whether the metering function is operating normally, locating faulty boards, and identifying preliminary causes. This effectively reduces the false alarm rate, shortens fault response time, and improves maintenance efficiency.

[0054] Optionally, the metering merging unit further includes a communication bus, and the main control board 30 and the metering board 40 are connected via the communication bus; the main control board 30 is used to detect the board presence status of each slot 20 through the communication bus, and perform initialization or removal operations according to the board presence status.

[0055] In this embodiment, the communication bus can be integrated into the backplane of the chassis 10, hereinafter referred to as the backplane bus. The backplane bus can include two types of physical channels: a high-speed data bus and a low-speed data bus. The high-speed data bus is used to transmit sampled value messages, while the low-speed management bus is used for board identification, status monitoring, and configuration distribution.

[0056] In this embodiment, each metering board 40 slot 20 may have an presence detection pin on the backplane, which is connected to the GPIO input of the main control board 30 through a pull-up resistor. When the metering board 40 is not inserted, the presence detection pin is high; after insertion, the board internally pulls it low, so that the main control board 30 can sense the presence status of the board in real time. Optionally, when the main control board 30 detects that a new metering board 40 has been inserted into a slot 20 (the presence detection pin level changes from high to low), it performs the following operations: delays for 100 ms to wait for the power supply and ground of the hot-swappable connector to stabilize; sends an "identity read" command to the board through the communication bus; the metering board 40 responds and returns the unique serial number, hardware version, and calibration information stored in its EEPROM; after verifying the compliance of the information, the main control board 30 issues operating parameters (such as sampling rate and channel mapping); and starts the data receiving channel of the board and adds it to the list of valid devices. When the board is detected to be removed (the level of the in-situ detection pin changes from low to high), the main control board 30 immediately stops receiving the data stream from the board, removes its logical address from the device list, and records the "board removal" event to the system log. If a redundant metering channel is configured, it automatically switches to the backup board to ensure uninterrupted output.

[0057] Understandably, although all metering boards 40 share a backplane physical connection, each metering board 40 has an independent analog front-end, ADC, and signal processing unit 44. Its sampling, filtering, compensation, and framing processes are all completed within the board, without relying on the main control board 30 or other board resources. The main control board 30 only acts as a data aggregation and protocol forwarding node and does not process the raw sampled values. Therefore, even if a metering board 40 fails or is being hot-swapped, the data acquisition and transmission of the remaining boards are completely unaffected, truly achieving functional decoupling and electrical isolation of the metering loop.

[0058] By integrating a communication architecture combining a high-speed data bus and a low-speed management bus on the backplane of chassis 10, board presence detection and automatic initialization are achieved, supporting true hot-swapping. The metering function is completely decentralized to the board level, with the main control board 30 only responsible for communication scheduling, ensuring metering independence and anti-interference capabilities. It has strong fault isolation, and single-board maintenance does not affect the overall system operation. The number of metering channels can be flexibly configured by increasing the number of slots 20, improving expansion flexibility.

[0059] This application also proposes a metering system, which includes a metering merging unit as described in any one of the above claims, and external equipment; The external device is communicatively connected to the main control board 30 of the metering merging unit. The external device is used to send external correction parameters to the main control board 30 when it receives an external trigger signal, so that the main control board 30 outputs the external correction parameters to the metering board 40.

[0060] In this embodiment, the external device can be a host computer or other terminal device. When on-site calibration or accuracy optimization of the metering system is required, the operator performs the following operations: connects the calibration device, starts the host computer software, calculates correction parameters, and sends an external trigger signal. The host computer automatically calculates the ratio correction factor, phase error compensation, and channel characteristic coefficient for each channel based on the comparison results between the standard source and the output of the merging unit. Maintenance personnel can click the "Issue Correction Parameters" button, and the host computer generates a configuration command (i.e., an external trigger signal) containing the above correction parameters, which is then sent to the main control board 30 via Ethernet. Furthermore, the operator can also issue forwarding and storage commands to the main control board 30 via the host computer. After receiving the command, the main control board 30 parses the target board address and parameter content, and writes the external correction parameters into a specified area of ​​the EEPROM non-volatile memory of the corresponding metering board 40 via the backplane management bus. In this way, the FPGA inside the metering board 40 automatically loads new parameters in the next sampling cycle and applies them to the error compensation calculation of all subsequent sampling data without the need for a restart or shutdown.

[0061] It should be noted that the host computer, as the human-machine interface, has the following specific functions and operating procedures: Before startup, the host computer's network card IP address must be set to 192.168.1.100, subnet mask 255.255.255.0, and gateway 192.168.1.1 to ensure normal communication with the main control board 30 of the merging unit, thus achieving network configuration. In the "Verification Configuration" tab of the host computer software panel, message parameter configuration can be sent, specifying the rated values ​​of output voltage / current, channel mapping relationship, the optical port used (optical port 1 or optical port 2), and sampling rate (4kHz / 12.8kHz). After completing the accuracy test, the ratio difference and angle difference values ​​obtained from the test are entered into this interface, and "Send" is clicked. After receiving the data, the merging unit stores these correction coefficients in the storage module 45 of the metering board 40 for real-time compensation. The CC value correction can be viewed manually or automatically obtained from the channel characteristic coefficients and sent to the merging unit.

[0062] In this embodiment, the metrological performance of the metrological merging unit prototype can be verified using the XL-805A merging unit calibrator (hereinafter referred to as the calibrator) manufactured by Xinglong Company. The calibrator has an accuracy class of 0.05 and can verify merging units with an accuracy class of 0.2 and below. Figure 8The diagram illustrates the verification principle of the metering system. The calibrator features a three-phase standard analog output interface (voltage and current), a 9-2 message input interface, a clock synchronization signal input and output interface, and a display interface for human-machine interaction. Based on this calibrator, a merging unit verification platform can be built. The specific verification steps are as follows: First, strictly follow the specifications for hardware connections. Connect the merging unit (the unit being calibrated) to the host computer (equipped with LabVIEW configuration and monitoring software) via its Ethernet port. Loop-connect the merging unit's clock synchronization signal input interface to the calibrator's clock synchronization signal output interface. Loop-connect the merging unit's clock synchronization signal output interface to the calibrator's clock synchronization signal input interface. Configure the TX terminal of the optical port used for outputting 9-2 messages to connect to the calibrator's optical Ethernet receiver. Connect the merging unit's three-phase voltage / current analog interface (A / D acquisition interface) to the calibrator's standard source output interface (i.e., the three-phase standard analog voltage and current output interface). Then, the following settings can be completed on the calibrator: Select IEC61850-9-2LE as the protocol; select either optical PPS output or optical IRIG-B output for the step signal based on the test item; set the number of samples according to the merging unit's sampling rate: 80 points for 4kHz sampling rate, and 256 points for 12.8kHz; set the voltage range to 10kV, the current range to 800A, and the rated value to 100V / 5A; set the data port to optical port one; ensure that the voltage and current channel numbers of the calibrator are consistent with the internal configuration of the merging unit. After configuration, accuracy testing (including voltage channel testing and current channel testing) can be performed. The specific procedure is as follows: Voltage channel test: Output voltage signals at 80%Un, 100%Un, and 120%Un sequentially on the calibrator, and record the ratio difference and angle difference of each phase at each point. Compare the maximum absolute value of the three-phase data at each range point with the accuracy requirement of the voltage channel of the merging unit to determine whether it is qualified.

[0063] Current path test: Output current signals of 1%In, 5%In, 20%In, 100%In, and 120%In sequentially on the calibrator and record the data. Determine the pass / fail status based on the standards for different points.

[0064] In addition, the specific steps of the synchronization performance testing process are as follows: Time synchronization test: In the "Time Synchronization Test" interface, set the synchronization signal type (PPS or B code), the test time to 10 minutes, and the MU stabilization time to 30 seconds. After the test starts, the system automatically records the time synchronization error. After the test, it determines whether the maximum / minimum error meets the requirement of ≤±1µs.

[0065] Timekeeping Test: After the synchronization signal stabilizes, wait 15-20 minutes, then set the timekeeping range to 4μs in the "Timekeeping Test" interface and test for 10 minutes. Determine if the timekeeping error meets the requirement of ≤±4µs.

[0066] Message Dispersion and Absolute Delay Test: In the "Transmission Delay" interface, set the test time to 10 minutes and start the test. The system automatically analyzes the temporal dispersion (dispersion, requirement ≤10µs) of the sampled values ​​in the message and the total transmission delay (requirement ≤1ms).

[0067] High and low temperature performance testing: The main body of the merging unit was placed inside a high and low temperature test chamber, while the calibrator was placed outside the chamber. Typical temperature points were selected within the range of -40℃ to 85℃. After stabilization at each temperature point, its temperature self-adaptation capability and the effectiveness of the error self-monitoring and compensation system were verified.

[0068] This invention achieves physical isolation of the metering circuit at the hardware level, reducing the impact of strong interference circuits such as protection and control circuits on the metering circuit channel and ensuring that the metering system achieves a metering accuracy of 0.2S level. Simultaneously, the metering board 40 supports online hot-swapping, allowing maintenance personnel to quickly replace the board while the metering system is powered on in case of failure or upgrade, achieving efficient operation and maintenance. Furthermore, the modular architecture effectively limits faults to a single board, allowing for independent metering functions and significantly extending the overall lifespan of the metering merging unit. More importantly, it possesses error self-monitoring capabilities; combined with a high-precision temperature sensor and dynamic compensation algorithm, it can perceive its own health status in real time, providing early warnings of accuracy drift and supporting predictive maintenance; even in... Even in harsh, wide-temperature environments ranging from 40℃ to +85℃, the system can automatically correct for temperature drift, ensuring metering performance. Thus, this invention's metering system transforms the metering function from the traditional "power outage maintenance" mode to a "hot-swappable online operation and maintenance" mode, improving the accuracy, reliability, and operation and maintenance efficiency of intelligent substation metering systems. This provides crucial equipment-level technical support for building the next generation of highly reliable, intelligent, and maintainable intelligent substations.

[0069] It is worth noting that since the power supply system of the present invention includes the DC output protection device described above, the embodiments of the power supply system of the present invention include all the technical solutions of all embodiments of the DC output protection device described above, and the technical effects achieved are exactly the same, so they will not be repeated here.

[0070] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A metering merging unit, characterized in that, The metering merging unit includes: The chassis has multiple slots for connecting metering boards, and a hot-swappable connector is connected to each slot inside the chassis. The main control board is located inside the chassis and is electrically connected to multiple hot-swappable connectors. The main control board is used to communicate with external devices and to detect the board presence status of each slot, and to perform initialization or removal operations according to the board presence status. At least one metering board, wherein the metering board is pluggably configured to be inserted into the slot; The hot-swappable connector has multiple pins of different lengths, and the longest pin among the multiple pins is the ground pin. When the metering board is connected to the slot, the metering board establishes an electrical connection path with the main control board through the multiple pins. The metering board is used to receive analog signals output by external sensors, process the analog signals, and output them to the main control board through multiple pins on the hot-swappable connector.

2. The metering merging unit as described in claim 1, characterized in that, The metering board includes: Input interface, used to receive analog signals output from external sensors; A signal conditioning circuit is electrically connected to the input interface. The signal conditioning circuit is used to receive the analog signal, perform signal preprocessing on the analog signal, and output a corresponding preprocessed signal. An analog-to-digital converter (ADC) is electrically connected to the signal conditioning circuit. The ADC is used to convert the preprocessed signal into a digital signal and output the corresponding digital signal. A signal processing unit is electrically connected to the analog-to-digital converter; The signal processing unit is used to control the sampling timing of the analog-to-digital converter, perform error compensation processing on the digital signal, and encapsulate the error-compensated digital signal into a digital message according to a preset protocol and output it to the main control board through multiple pins on the hot-swappable connector.

3. The metering merging unit as described in claim 2, characterized in that, The signal processing unit includes: A clock synchronization module is used to receive an external pulse reference signal, process the pulse reference signal, and output a corresponding local sampling clock signal. A sampling control module is electrically connected to the clock synchronization module. The sampling control module is used to output a corresponding sampling control signal to the analog-to-digital converter according to the local sampling clock signal, so as to control the sampling timing of the analog-to-digital converter. An error compensation module is electrically connected to the analog-to-digital converter. The error compensation module is used to receive external correction parameters and perform error compensation processing on the digital signal according to the external correction parameters. The message framing module is electrically connected to the error compensation module. The message framing module is used to encapsulate the error-compensated digital signal into a digital message according to a preset protocol and then output it to the main control board.

4. The metering merging unit as described in claim 3, characterized in that, The signal processing unit further includes: The self-test control module is electrically connected to the analog-to-digital converter and the error compensation module, respectively. A switching circuit is provided, wherein a first input terminal of the switching circuit is used to connect an external sensor, a second input terminal of the switching circuit is used to connect an internal reference voltage, and an output terminal of the switching circuit is electrically connected to the input terminal of the analog-to-digital converter. The switching circuit is used to connect the electrical connection between the first input terminal and the output terminal or to connect the electrical connection between the second input terminal and the output terminal. The analog-to-digital converter is used to sample the internal reference voltage and output a corresponding sampling signal to the self-test control module when the switching circuit connects the second input terminal and the output terminal. The self-test control module is used to compare the sampled signal with the preset sampled value and output the corresponding error comparison result to the error compensation module, so that the error compensation module can perform error compensation processing on the digital signal according to the external correction parameters and the error comparison result.

5. The metering merging unit as described in claim 2, characterized in that, The metering board also includes: A storage module is electrically connected to the signal processing unit, and the storage module is used to store at least one of the following: the identity information, production information, and external correction parameters of the metering board.

6. The metering merging unit as described in claim 2, characterized in that, The metering board also includes: A digital temperature sensor is electrically connected to the signal processing unit; The digital temperature sensor is used to detect the temperature of the metering board and output the corresponding temperature detection signal to the signal processing unit.

7. The metering merging unit as described in claim 1, characterized in that, The metering merging unit also includes a status indicator light, which is electrically connected to the main control board. The main control board is used to control the status indicator light to work / stop working based on the board's in-place status.

8. The metering merging unit as described in any one of claims 1 to 7, characterized in that, The metering merging unit also includes a communication bus, and the main control board and the metering board are connected via the communication bus. The main control board is used to detect the board presence status of each slot through the communication bus, and perform initialization or removal operations according to the board presence status.

9. The metering merging unit as described in any one of claims 1 to 7, characterized in that, The metering merging unit further includes: A reference voltage source, which is electrically connected to the metering board; The reference voltage source is used to provide an internal reference voltage to the metering board.

10. A metering system, characterized in that, The metering system includes a metering merging unit as described in any one of claims 1 to 9, and external devices; The external device is communicatively connected to the main control board of the metering merging unit. The external device is used to send external correction parameters to the main control board when it receives an external trigger signal, so that the main control board outputs the external correction parameters to the metering board.

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