A distribution line terminal sensing terminal and line status monitoring method

Abstract

The present invention relates to a distribution line end sensing terminal and a line status monitoring method. A distribution line end sensing terminal comprises: a controller, a positioning device, an uplink communicator, a downlink communicator, an AC high-voltage sensor, an exchange meter and a first memory; the positioning device, the uplink communicator, the downlink communicator, the AC high-voltage sensor and the exchange meter are respectively connected to the controller; the sensing terminal is communicatively connected to the uplink device via the uplink communicator. The distribution line end sensing terminal and line status monitoring method provided by the present invention have the following effects: 1) The present invention adopts an external open-close current transformer with a high accuracy level, an operating environment temperature range of ‑40°C to 85°C, and a strong anti-interference ability; 2) The present invention realizes residual current monitoring by adopting a multifunctional high-precision three-phase electric energy dedicated metering chip, and has the functions of residual current monitoring and over-limit event reporting.

Description

Technical Field

[0001] The present invention relates to the field of power distribution line monitoring, and in particular to a power distribution line terminal sensing terminal and a line status monitoring method. Background Art

[0002] The low-voltage distribution network is at the end of the entire power grid. For a long time, due to the characteristics of the low-voltage distribution network, which is numerous, wide, large in volume, and has low economic value per point, as well as the limitations of factors such as investment costs, human resources and technical levels of power grid companies, the focus of distribution network transformation has been mainly on 10kV and above networks. Distribution automation has not yet effectively covered the low-voltage distribution network. As the "last mile", the low-voltage distribution network has long been in a monitoring blind spot and has long lacked intelligent and efficient operation monitoring and operation and maintenance management methods.

[0003] At the 2019 "Two Sessions", State Grid Corporation of China proposed building a power distribution Internet of Things with extensive equipment interconnection, comprehensive status perception, plug-and-play equipment, flexible application iteration, efficient resource utilization, and fast and intelligent decision-making. Among them, comprehensive status perception mainly relies on the low-voltage distribution network perception layer. The perception layer is mainly used to realize the monitoring, collection and perception of basic data such as the operating environment of distribution equipment, equipment status, and electrical quantity information. The perception layer currently has seriously insufficient coverage and poor real-time performance.

[0004] The perception layer equipment is mainly composed of the bottom-level "end" layer equipment in the low-voltage distribution network architecture. The "end" is the access unit in the low-voltage distribution network that connects "things" to the "Internet". It is the perception layer and execution layer in the low-voltage distribution network architecture. It is responsible for providing the source of basic data such as the operating status, equipment status, environmental status and other auxiliary information of the distribution network to the edge or cloud. It is the terminal for executing decision-making commands or on-site control.

[0005] Among them, there is a type of "end" layer equipment that is mainly used to monitor and measure electrical quantities such as voltage and current and switch quantities at branch boxes and meter boxes, and on this basis realize functions such as electricity metering line loss analysis, power outage and power-on status monitoring, and event reporting. At present, there is no unified technical specification and standard for this type of product among power grid companies. The form and function of this type of product on the market are customized by manufacturers according to different needs, resulting in different forms, communication methods and functions of this type of product on the market. Similar products on the market also have the following disadvantages: (1) The current sampling and metering accuracy is not high. Most of the current sampling products are manufactured according to the level 1 accuracy. Most of the current sampling uses external open-close current transformers made of ferrite or silicon steel sheets. This type of transformer has poor performance and is easily interfered with in some special application scenarios, resulting in poor accuracy. For example, the low-temperature performance can only reach -25℃. When the temperature exceeds this, the accuracy will be out of tolerance. For example, in a strong magnetic field environment (0.5mT), the current sampling accuracy will be greatly out of tolerance. (2) The uplink communication method of existing products is single and the compatibility is not strong. Many of them also use low-speed communication methods such as RS485 communication, narrowband communication or LORA wireless communication. In addition, most of the uplink communication modules are (1) The existing products do not have the precise positioning of the equipment and the geographical location of the household meter in the substation; (2) The business application functions and external interfaces are single, and the compatibility and scalability are not strong, and the functional transformation and business adjustment cannot be realized quickly and at low cost; (3) The existing products do not have the residual current monitoring and over-limit reporting; (4) The existing products do not have the precise positioning of the equipment and the geographical location of the household meter in the substation; (5) The business application functions and external interfaces are single, and the compatibility and scalability are not strong, and the functional transformation and business adjustment cannot be realized quickly and at low cost; (6) The existing products do not have the residual current monitoring and over-limit reporting; (7) The high-frequency collection of the 5-minute line operation status data and the 15-minute electricity meter load data of the terminal power grid cannot be realized, and the meter box line loss analysis and calculation cannot be combined with the terminal meter box metering data and the electricity meter metering data to realize the local perception of the meter box line loss and the power theft analysis decision and upload to the upper terminal and the main station.

[0006] Patent document ZL 201910227388.1 discloses a low-voltage distribution network terminal perception system and method based on the Internet of Things, including a substation intelligent perception terminal, a branch box monitoring unit, a meter box monitoring unit and a user power monitoring module; the substation intelligent perception terminal is connected to the branch box monitoring unit and the meter box monitoring unit to notify the identification of physical topology relationships and obtain the operating status data of each line of the low-voltage distribution network and the user's electricity meter data; the meter box monitoring unit is connected to the user power monitoring module to obtain the user's switch status. The present invention also discloses a method for utilizing the above-mentioned low-voltage distribution network terminal perception system based on the Internet of Things, which enriches the functions of the existing electricity consumption information collection system, but the terminal perception terminal still has the above-mentioned problems.

[0007] Therefore, the monitoring accuracy and functionality of the terminal acquisition terminals in the existing distribution line monitoring field are still insufficient and need to be improved and enhanced. Summary of the Invention

[0008] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a distribution line end sensing terminal and a line status monitoring method, which can improve measurement accuracy and have a reporting function for real-time monitoring of the distribution line status.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A distribution line end sensing terminal, comprising: a controller, a positioning device, an uplink communicator, a downlink communicator, an AC high-current sensor, an electric power meter, and a first memory; the positioning device, the uplink communicator, the downlink communicator, the AC high-current sensor, and the electric power meter are respectively connected to the controller; the sensing terminal is connected to an uplink device via the uplink communicator and is connected to a plurality of electric energy meters via the downlink communicator; the memory is connected to the controller;

[0011] The cross-collection meter includes: a meter manager, a meter, a three-phase voltage sampler, a three-phase current sampler, a residual current sampler, and a second memory; the three-phase voltage sampler, the three-phase current sampler, and the residual current sampler are respectively connected to the meter; the meter and the memory are respectively connected to the meter manager; and the meter manager is connected to the controller.

[0012] Preferably, the distribution line end sensing terminal, the three-phase voltage sampler includes an A-phase voltage sampling unit, a B-phase voltage sampling unit, and a C-phase voltage sampling unit; the A-phase voltage sampling unit, the B-phase voltage sampling unit, and the C-phase voltage sampling unit all use the same voltage acquisition unit to respectively collect voltage data in the three-phase line;

[0013] The voltage sampling unit includes a voltage terminal, an overvoltage protection circuit, a current limiting voltage divider, a voltage transformer, a voltage resistance sampling circuit and a voltage filtering circuit which are connected in sequence; the voltage filtering circuit is connected to the meter.

[0014] Preferably, the distribution line end sensing terminal, the three-phase current sampler includes an A-phase current sampling unit, a B-phase current sampling unit, and a C-phase current sampling unit; the A-phase current sampling unit, the B-phase current sampling unit, and the C-phase current sampling unit all use the same current sampling unit to respectively collect current data in the three-phase line;

[0015] The current sampling unit includes an external current transformer, a current terminal, a current resistance sampling circuit, and a current filtering circuit which are connected in sequence; the current filtering circuit is connected to the meter.

[0016] Preferably, the distribution line end sensing terminal, the residual current sampler includes a residual current transformer, a residual current terminal, a residual current resistance sampling circuit, and a residual current filter circuit connected in sequence; the residual current filter circuit is connected to the meter.

[0017] Preferably, the distribution line end sensing terminal, the AC strong current sensor includes an AC strong current overvoltage protector, an AC strong current limiter, an optocoupler reverse protection device and an AC strong current isolator connected in sequence; the AC strong current isolator is connected to the controller.

[0018] A method for monitoring the state of a distribution line using the distribution line terminal sensing terminal comprises the following steps:

[0019] S1, the sensing terminal receives the detection data from the AC strong current sensor and the cross-collection meter in the terminal line, as well as the data from multiple connected electric energy meters, generates line operation data, stores it in the first memory, and waits for reading by the upper device;

[0020] S2. The perception terminal analyzes and processes the line operation data to determine whether there is an abnormal event in the substation line. When an abnormality occurs, the perception terminal actively reports the abnormality to the upper-level device.

[0021] Preferably, the distribution line status monitoring method comprises the line operation data including real-time exchange data of the distribution line, statistical data on qualified line voltage, 5-minute accuracy curve data of the distribution line, 15-minute accuracy curve data of all connected electric energy meters, hourly frozen data of the distribution line, daily frozen data of the distribution line, and hourly frozen data of the distribution line loss; the electric energy meter data comprises hourly frozen data of the electric energy meter, and daily frozen data of the electric energy meter;

[0022] The abnormal line operation events include line loss exceeding limit and recovery events, distribution line power outage and recovery events, voltage exceeding limit and recovery events, voltage loss and recovery events, current loss and recovery events, three-phase current imbalance and imbalance recovery events, residual current exceeding limit and recovery events, and line impedance exceeding limit and recovery events.

[0023] Preferably, the method for monitoring the state of a distribution line, step S1 specifically includes:

[0024] S11, the meter collects in real time the three-phase voltage data detected by the three-phase voltage sampler, the three-phase current data detected by the three-phase current sampler, and the residual current data detected by the residual current sampler, and updates them to the metering manager at a predetermined frequency;

[0025] S12. The metering manager obtains active power data of the distribution area based on the three-phase voltage data and the three-phase current data, thereby obtaining electric energy data, and stores the active power data and the electric energy data in the second memory;

[0026] S13, the controller obtains the three-phase voltage data, three-phase current data, active power data, and electric energy data from the metering manager at a first predetermined interval, and generates operation data of the current line by combining the operation data of each electric energy meter obtained by the controller from all connected electric energy meters;

[0027] S14. The controller stores the line operation data in the first memory and waits for the upstream device to read it.

[0028] Preferably, in the distribution line status monitoring method, in step S2, the line loss exceeding limit and recovery event detection specifically includes:

[0029] S21. Calculate the current hourly line loss: Subtract the sum of the total forward active energy data in the hourly frozen data of all connected electric energy meters from the total forward active energy data in the hourly frozen data of the distribution line on the sensing terminal to obtain the current hourly total forward active energy line loss data of the line;

[0030] S22. Calculate the incremental line loss data for the previous hour: Subtract the total forward active energy line loss for the previous hour from the total forward active energy line loss for the current hour to obtain the incremental line loss data for the total forward active energy line loss for the current hour.

[0031] S23, calculating the incremental total forward active electric energy of the line in the previous hour: subtracting the current total forward active electric energy frozen at the previous hour of the sensing terminal from the current hourly total forward active electric energy data in the hourly frozen data of the distribution line of the sensing terminal, to obtain the incremental total forward active electric energy data of the line in the previous hour;

[0032] S24. Calculate the terminal line loss rate: The terminal line loss rate calculation formula is:

[0033]

[0034] Where R is the line loss rate in the previous hour; △S is the total forward active energy increment of the line in the previous hour; S nS is the total forward active electric energy data of the current hour of the sensing terminal; n-1 The current total forward active electric energy frozen at the hour of the last hour of the sensing terminal; △E is the line loss increment of the total forward active electric energy in the last hour; E n E is the total forward active energy line loss in the current hour; n-1 The total forward active energy line loss in the previous hour;

[0035] S25. Line loss exceeding limit event determination: The controller determines whether the current line loss rate is greater than the line loss alarm threshold. If so, it determines that a line loss exceeding limit event has occurred, records and immediately reports the event to the uplink device, and executes step S26. If not, it executes step S27.

[0036] S26, line loss recovery event determination: The controller determines in real time whether the current line loss rate is lower than the line loss recovery threshold. If so, it determines that a line loss recovery event has occurred, records the abnormal recovery, and reports it to the upstream device, and executes step S27; if not, executes step S27;

[0037] S27. Line loss freezing at the hour: the sensing terminal executes steps S21 to S25 at every hour to obtain and generate hourly line loss freezing data for this line for 24 hours.

[0038] Preferably, in the distribution line status monitoring method, the detection operation of the residual current over-limit and recovery event in step S2 specifically includes:

[0039] S201, the residual current sampler detects the residual current in the terminal line of the substation in real time, and sends the detected residual current to the meter in real time, and the meter sends the detected residual current to the metering manager;

[0040] S202, the metering manager determines whether the detected residual current is greater than the over-limit value and the duration is greater than the first recovery time. If so, it is determined that the residual current over-limit event persists and step S203 is executed; if not, step S201 is executed;

[0041] S203, storing the residual current exceeding limit event in the second memory, and sending the residual current exceeding limit event to the controller, the controller sending the residual current exceeding limit event to the server, and executing step S204;

[0042] S204, the metering manager determines whether the detected residual current is less than or equal to the return current and the duration is greater than the set second recovery time. If so, it is determined that the over-limit event has disappeared and the substation line has returned to normal, and step S205 is executed; if not, step S203 is executed;

[0043] S205: Send the line restoration information to the controller. The controller sends the line restoration information to the server, and then execute step S201.

[0044] Compared with the prior art, the distribution line terminal sensing terminal and line status monitoring method provided by the present invention have the following effects:

[0045] 1) The present invention adopts an external split-type current transformer with high precision, excellent performance, an operating temperature range of -40°C to 85°C, and strong anti-interference ability;

[0046] 2) The present invention realizes residual current monitoring by adopting a multifunctional high-precision three-phase electric energy dedicated metering chip, and has the functions of residual current monitoring and over-limit event reporting;

[0047] 3) The present invention analyzes and processes the distribution line operation data, determines that when a line abnormality occurs, it actively reports the abnormality to the upstream equipment;

[0048] 4) The present invention can realize high-frequency collection of 5-minute accurate line operation status data of distribution lines and 15-minute accurate load data of all connected electric energy meters, and combine the distribution line metering data with the electric energy meter metering data to perform line loss analysis and calculation, supporting local perception of line loss and electricity theft analysis and decision-making. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a structural block diagram of the terminal sensing terminal in the present invention;

[0050] Figure 2 This is a structural block diagram of the A-phase voltage sampling unit in the three-phase voltage sampler of the present invention;

[0051] Figure 3 This is a circuit diagram of the A-phase voltage sampling unit in the three-phase voltage sampler of the present invention;

[0052] Figure 4 This is a structural block diagram of the A-phase current sampling unit in the three-phase current sampler of the present invention;

[0053] Figure 5 This is a circuit diagram of the A-phase current sampling unit in the three-phase current sampler of the present invention;

[0054] Figure 6 It is a structural block diagram of the residual current sampler in the present invention;

[0055] Figure 7 is a circuit diagram of the residual current sampler of the present invention;

[0056] Figure 8This is a structural block diagram of the traffic intensity perception module in the present invention;

[0057] Figure 9 It is a circuit diagram of the traffic intensity sensing module in the present invention. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0059] Please also refer to Figures 1-9 , in the attached Figure 3 , Attachment Figure 5 , Attachment Figure 7 The metering chip D4 and the attached Figure 9 The processor chip U1 in the controller 1 is a well-known technology in the art, and only some details are shown, which does not affect the understanding of this technical solution.

[0060] The present invention provides a distribution line end sensing terminal, comprising: a controller 1, a positioning device 4, an uplink communicator 5, a downlink communicator 6, an AC strong current sensor 3, an inter-collection meter 2, and a first memory 7; the uplink communicator 5, the downlink communicator 6, the AC strong current sensor 3, and the inter-collection meter 2 are respectively connected to the controller 1; the sensing terminal is connected to an uplink device (an upper terminal or a host computer, etc.) through the uplink communicator 5, and is connected to a plurality of electric energy meters through the downlink communicator 6; the first memory 7 is connected to the controller 1;

[0061] The cross-collection meter 2 includes: a meter manager 21, a meter 22, a three-phase voltage sampler 23, a three-phase current sampler, a residual current sampler, and a second memory; the three-phase voltage sampler 23, the three-phase current sampler 24, and the residual current sampler 25 are respectively connected to the meter 22; the meter 22 and the memory are respectively connected to the meter manager 21; the meter manager 21 is connected to the controller 1.

[0062] Specifically, the terminal sensing terminal is generally used for node data statistics on the terminal line of the substation area and identification of over-limit events (electricity theft, etc.); generally, it is connected to multiple electricity meters to collect data uploaded by the electricity meters and manage and analyze the terminal line data of this node or even this substation area; preferably, the controller 1 adopts Renesas R5F51138 processor chip U1 (see Figure 7); the first memory 7 adopts a memory model W25Q256 of Winbond Corporation; the first memory 7 is connected to the controller 1 through an SPI interface; the downlink communicator 6 is preferably an RS485 communication device, connected to the controller 1 through a UART serial port; the cross-collection meter 2 is connected to the controller 1 through a UART serial port; the uplink communicator 5 is preferably a Neusoft sixth-generation I-collection high-speed HPLC carrier module with a model number of PLCS1667-D-CJQ-GW13 of Qingdao Neusoft Carrier Technology Co., Ltd. The module has its own supercapacitor and can support terminal power outage event reporting through HPLC carrier signal coupling after the terminal power outage. It is connected to the controller 1 through a standard interface, and the standard interface is a detachable standard interface in this field; the AC strong current sensor 3 is used to sense the power-off status information of a single electric energy meter. The uplink device can be a station master station, a server, etc., or other terminal host computers, or a general host controller, computer, etc. The present invention does not make specific restrictions.

[0063] The cross-collection meter 2 is used to monitor the line operation status, measure parameters such as three-phase voltage, three-phase current, residual current, active power, reactive power, power factor, and electric energy, and provide basic data for load data monitoring and line loss analysis. The three-phase voltage sampler 23 is used to sample the voltage of the three-phase lines A, B, and C; the three-phase current sampler 24 is used to sample the current of the three-phase lines A, B, and C; the residual current sampler 25 is used to sample the residual current; the meter 22 is preferably the ATT7022E multifunctional high-precision three-phase electric energy dedicated metering chip D4 of Juquan Company (please refer to Figure 3 、 Figure 5 、 Figure 7 ), used to receive parameters such as the three-phase line voltage RMS, three-phase line current RMS, power factor, phase angle, frequency, active electric energy and reactive electric energy; the second memory adopts ATMEL's AT24C256 EEPROM memory, used to store metering parameters and power data; the metering manager 21 preferably adopts Fudan Microelectronics FM33A048 single-chip microcomputer; the meter 22 is connected to the metering manager 21 via an SPI interface.

[0064] Accordingly, the present invention also provides a method for monitoring the status of a distribution line, comprising the steps of:

[0065] S1, the sensing terminal receives the detection data in the terminal line of the AC strong current sensor 3 and the cross-collection meter 2, as well as the electric energy meter operation data reported by the multiple electric energy meters connected thereto, generates line operation data, stores it in the first memory 7, and waits for receiving the data call command from the upper device or the master station to upload the data;

[0066] S2. The sensing terminal processes the line operation data to determine whether there is an abnormal line operation event at the end of the substation, and actively reports the abnormal event to the master station uplink device in real time.

[0067] As a preferred solution, in this embodiment, the line operation data includes real-time distribution line exchange data, line voltage qualification statistics, 5-minute distribution line accuracy curve data, 15-minute accuracy curve data of all connected electric energy meters, distribution line hourly frozen data and distribution line daily frozen data, distribution line line loss hourly frozen data; the electric energy meter data includes electric meter hourly frozen data and electric meter daily frozen data;

[0068] The abnormal line operation events include line loss exceeding limit and recovery events, distribution line power outage and recovery events, voltage exceeding limit and recovery events, voltage loss and recovery events, current loss and recovery events, three-phase current imbalance and imbalance recovery events, residual current exceeding limit and recovery events, and line impedance exceeding limit and recovery events.

[0069] As a preferred solution, in this embodiment, the three-phase voltage sampler 23 includes an A-phase voltage sampling unit (not shown), a B-phase voltage sampling unit (not shown), and a C-phase voltage sampling unit (not shown); the A-phase voltage sampling unit, the B-phase voltage sampling unit, and the C-phase voltage sampling unit all use the same voltage acquisition unit to respectively collect voltage data in the three-phase line;

[0070] The voltage sampling unit includes a voltage terminal 231, an overvoltage protection circuit 232, a current limiting voltage divider 233, a voltage transformer 234, a voltage resistance sampling circuit 235, and a voltage filter circuit 236 connected in sequence; the voltage filter circuit 236 is connected to the meter 22. The voltage terminal 231 preferably adopts a 4-core elbow socket XS4 for three-phase four-wire 220V AC power access. The Phoenix company's 4-core elbow socket specification is GMSTB. 2,5 / 4-GF-7,62; the overvoltage protection circuit 232 is mainly implemented by the varistor RV2, and the varistor RV2 adopts the MYN15-821K of Chengdu Tieda Electronics Co., Ltd., and the varistor voltage is 820V±10%; the current limiting voltage divider 233 is preferably composed of 6 high-precision and low-temperature drift resistors (resistor R17, resistor R18, resistor R20, resistor R21, resistor R22, resistor R23) in series, and the package is 1206 package (a packaging method in this field), the resistance accuracy requirement is 0.5%, and the temperature drift coefficient is 25PPM, wherein one resistor has a resistance of 100kΩ (for example, resistor R17 is 100kΩ), and the remaining 5 resistors have a resistance of 33kΩ (for example, resistor R18, resistor R20, resistor R21, resistor R23). 2. The resistance of resistor R23 is 33kΩ), and the total resistance of the 6 current-limiting resistors is about 265kΩ; the voltage transformer 234 preferably adopts the HPT225A-G voltage transformer CT of Beijing Huoyuan Technology Co., Ltd., with the main parameters of which are a parameter ratio of 2mA / 2mA, a withstand voltage of 2500VAC, and an accuracy level of 0.1; the voltage resistance sampling circuit 235 adopts differential sampling and is composed of two high-precision and low-temperature drift resistors (resistor R19 and resistor R24), each with a resistance of 30Ω; the voltage filter circuit 236 adopts an RC filter circuit (composed of a resistor R16, a resistor R25, a capacitor C17, and a capacitor C18), wherein the resistor R19 and the resistor R24 ​​are both 1.2KΩ, and the capacitance of the capacitor C17 and the capacitor C18 are both 0.01uf.

[0071] Specifically, the three-phase voltage sampler 23 is used for sampling the three-phase 220V AC voltage of the strong power, and the A-phase voltage sampling unit, the B-phase voltage sampling unit, and the C-phase voltage sampling unit are all connected to the meter 22 .

[0072] The principle of cross-voltage sampling is now described in detail using phase A as an example. The phase A voltage sampling unit includes a phase A voltage terminal 231, a phase A overvoltage protection circuit 232, an A current limiting voltage divider 233, a phase A voltage transformer 234, a phase A voltage resistor sampling circuit 235, and a phase A voltage filter circuit 236, which are connected in sequence. The phase A AC power first enters the phase A overvoltage protection circuit 232 through the phase A voltage terminal 231, then passes through the phase A current limiting resistor divider to convert the 220V AC voltage into a small voltage signal. The small voltage signal is then converted into an isolated small current signal through the phase A voltage transformer 234, and then converted into a small voltage signal through the subsequent phase A voltage resistor sampling circuit 235. Finally, the small voltage signal is input into the V2P and V2C differential ADC analog-to-digital conversion pins of the metering chip ATT7022E in the meter 22 through the phase A voltage filter circuit 236.

[0073] As a preferred solution, in this embodiment, the three-phase current sampler 24 includes an A-phase current sampling unit (not shown), a B-phase current sampling unit (not shown), and a C-phase current sampling unit (not shown); the A-phase current sampling unit, the B-phase current sampling unit, and the C-phase current sampling unit all use the same current sampling unit to respectively collect current data in the three-phase line;

[0074] The current sampling unit includes an external current transformer 241 , a current terminal 242 , a current resistance sampling circuit 243 , and a current filter circuit 244 , which are connected in sequence. The current filter circuit 244 is connected to the meter 22 . The external current transformer 241 preferably adopts the HCT22K-A1 current transformer of Beijing Huoyuan Technology Co., Ltd., with a rated current of 100A, a CT ratio of 4000:1, a maximum current of up to 400A, and an accuracy level of 0.5; the current terminal 242 adopts a 6-core plug-in terminal socket XS3, and can adopt the terminal socket model MB1.5 / V3.81 / 06-GN of Utele Electric Co., Ltd.; the current resistance sampling circuit 243 adopts differential sampling and is composed of two high-precision and low-temperature drift resistors (resistor R12 and resistor R13), both of which have a resistance value of 3.3Ω; the current filter circuit 244 adopts an RC filter circuit (composed of resistor R11, resistor R14, capacitor C15 and capacitor C16), wherein the resistor R11 and the resistor R14 are both 1.2KΩ, and the capacitance of capacitor C15 and capacitor C16 are both 0.01uf.

[0075] Specifically, the three-phase current sampler 24 is mainly responsible for three-phase AC current sampling. The AC current sampling principle is now described in detail taking phase A as an example. The phase A current sampling unit includes an A-phase external current transformer 241, an A-phase current terminal 242, an A-phase current resistor sampling circuit 243, and an A-phase current filter circuit 244; the A-phase AC current is sampled through the A-phase external current transformer 241, and the large current is converted into a small current signal according to a certain transformation ratio. The small current signal passes through the A-phase current terminal 242 and then through the subsequent A-phase resistor sampling circuit to convert it into a small voltage signal. Then, the small voltage signal is finally input into the V1P and V1N differential ADC analog-to-digital conversion pins of the dedicated metering chip ATT7022E in the meter 22 through the A-phase filter circuit.

[0076] As a preferred solution, in this embodiment, the residual current sampler 25 includes a residual current transformer 251, a residual current terminal 252, a residual current resistance sampling circuit 253, and a residual current filter circuit 254, which are connected in sequence; the residual current filter circuit 254 is connected to the meter 22. Specifically, the residual current sampling circuit is primarily responsible for residual current sampling. That is, during sampling, four wires in a three-phase four-wire line simultaneously pass through the residual current transformer 251 for detection. The residual current transformer 251 adopts the CTZK5Y-10 current transformer of Jinan Shenghong Electronics Co., Ltd., with a rated current of 1A, a CT ratio of 2000:1, a maximum current of up to 2A, and an accuracy level of 1; the residual current terminal 252 adopts the terminal socket XS2 with model specification MB1.5 / V3.81 / 02-GN of Utele Electric Co., Ltd.; the residual current resistance sampling circuit 253 adopts differential sampling and is composed of two high-precision and low-temperature drift resistors (resistor R8 and resistor R9), both of which have a resistance of 200Ω. The residual current filter circuit 254 adopts an RC filter circuit (composed of resistor R7, resistor R10, capacitor C13 and capacitor C14), wherein the resistor R7 and the resistor R10 both have a value of 1.2KΩ, and the capacitance of capacitor C13 and capacitor C14 are both 0.01uf.

[0077] The residual current is first sampled by the residual current transformer 251, where the large current is converted into a small current signal according to a certain transformation ratio. The residual current then passes through the residual current terminal 242 and is converted into a small voltage signal by the subsequent residual current resistor sampling circuit 253. After passing through the residual current filter circuit 254, the small voltage signal is finally input into the V0P and V0N differential ADC analog-to-digital conversion pins of the dedicated metering chip ATT7022E in the meter 22.

[0078] As a preferred solution, in this embodiment, the external current transformer 241 is a current transformer with an accuracy level of 0.5; the residual current transformer 251 is a current transformer with an accuracy level of 1. Both the external current transformer 241 and the residual current transformer 251 are made of amorphous or permalloy materials, have high accuracy levels, can meet the 0.5 accuracy level for current sampling, have excellent performance, a wide operating temperature range (ambient operating temperature can be between -40°C and 85°C), and strong anti-interference capabilities.

[0079] As a preferred solution, in this embodiment, the AC high-current sensor 3 includes an AC high-current overvoltage protector 31, an AC high-current current limiter 32, an optocoupler reverse current protector 33, and an AC high-current isolator 34, which are connected in sequence; the AC high-current isolator 34 is connected to the controller 1. The high-current sensor is used to sense and monitor the power-on and power-off status of a single electric energy meter user. Here, AC high-current mainly refers to 220V AC power, and is connected to the controller 1 via an IO port. The AC high-voltage overvoltage protector 31 is mainly used for overvoltage protection and suppressing transient overvoltage protection of subsequent devices. It is preferred to use a varistor RV1 for overvoltage protection to prevent overvoltage shocks such as lightning surges from damaging the detection circuit. The varistor RV1 can use EPSON's S14K680E2, and its main specifications are: maximum continuous working DC voltage and maximum continuous AC voltage AC: 420Vrms, DC: 560V, varistor voltage 680V, ​​surge current 5000A, and maximum limit clamping voltage 1100V; the AC high-voltage current limiter is mainly used to provide a suitable drive current drive isolation device, using three 100K resistors in 1206 packages (resistor R3, resistor R4, resistor R5); the optocoupler reverse protector 33 uses a rectifier diode D1 to protect the optocoupler from reverse breakdown. The 1N4007 rectifier diode of Yangzhou Yangjie Electronic Technology Co., Ltd. can be selected, with a reverse withstand voltage of 1000V, and its specifications are: D0-41 Vrrm: 1000VVrms: 700V If: 1A-65℃~175℃; The AC strong current isolator 34 is mainly used to isolate the AC 220V strong current from the weak current system to prevent users from electric shock. An isolation optocoupler D2 is used, and an isolation optocoupler of Lite-On model LTV-816S can be used. After the AC strong current signal passes through the isolation optocoupler, pin 3 of the optocoupler is connected to pin P11 of the controller 1 (processor chip U1).

[0080] As a preferred solution, this embodiment also includes a positioning device 4, which includes a GPS device and a Beidou device, which is used for accurate clock synchronization and positioning of geographical location information such as longitude and latitude. The Beidou & GPS dual-mode module adopts the SIM68VB Beidou & GPS navigation module of SIMCOM. The R5F51138 microcontroller is connected to and communicates with the SIM68VB Beidou & GPS navigation module through the UART serial port. The SIM68VB Beidou & GPS navigation module is also connected to the antenna.

[0081] As a preferred solution, in this embodiment, step S1 specifically includes:

[0082] S11, the meter 22 collects the three-phase voltage data detected by the three-phase voltage sampler 23, the three-phase current data detected by the three-phase current sampler 24, and the residual current data detected by the residual current sampler 25 in real time, and sends the detection data to the meter manager 21 in real time, and the meter manager 21 reads the real-time detection data in the meter 22 at a predetermined frequency and stores it in the second memory;

[0083] S12, the metering manager 21 obtains active power data of the distribution area according to the three-phase voltage data and the three-phase current data, thereby obtaining electric energy data, and stores the active power data and the electric energy data in the second memory;

[0084] S13, the controller 1 obtains the three-phase voltage data, three-phase current data, active power data, electric energy data and other data from the metering manager 21 at a first predetermined interval, and generates substation terminal line operation data by combining the operation data of each electric energy meter obtained by the controller 1 from all connected electric energy meters;

[0085] S14. The controller 1 stores the line operation data in the first memory 7, and uploads the data according to the call command of the uplink device.

[0086] Among them, the voltage qualification rate statistical data is mainly used to count the operating voltage of the terminal line, which is divided into daily frozen data and monthly frozen data. The daily frozen data is stored for 4 days, and the monthly frozen data is stored for 4 months. The 5-minute curve data mainly includes ABC three-phase voltage, ABC three-phase current, residual current, ABC three-phase and combined phase active power, ABC three-phase and combined phase power factor, ABC three-phase and combined phase electric energy, and the storage time is continuous storage for 3 days. The hourly frozen data is stored across the clock every day, mainly storing the total active power data of forward and reverse directions, and the storage time is continuous storage for 24 hours. The daily frozen data is stored across the day every day, mainly storing the total active power data of forward and reverse directions, and the daily frozen data is stored continuously for 12 days.

[0087] As a preferred solution, in this embodiment, in step S2, the line loss exceeding limit and recovery event detection specifically includes:

[0088] S21. Calculate the current hourly line loss: Subtract the sum of the total forward active energy data in the hourly frozen data of all connected electric energy meters from the total forward active energy data in the hourly frozen data of the distribution line on the sensing terminal to obtain the current hourly total forward active energy line loss data of the line;

[0089] S22. Calculate the incremental line loss data for the previous hour: Subtract the cumulative line loss for the previous hour from the cumulative line loss for the current hour to obtain the incremental line loss data for the total forward active energy on the line for the previous hour.

[0090] S23, calculating the incremental total forward active electric energy of the line in the previous hour: subtracting the current total forward active electric energy frozen at the hour of the previous hour from the current total forward active electric energy data of the sensing terminal in the current hour, to obtain the incremental total forward active electric energy data of the line in the previous hour;

[0091] S24. Calculate the terminal line loss rate: The terminal line loss rate calculation formula is:

[0092]

[0093] Where R is the line loss rate in the previous hour; △S is the total forward active energy increment of the line in the previous hour; S n Freeze the current forward active total electric energy data for the current hour of the sensing terminal; S n-1 The current total forward active electric energy frozen at the hour of the last hour of the sensing terminal; △E is the line loss increment of the total forward active electric energy in the last hour; E n E is the total forward active energy line loss in the current hour; n-1 The total forward active energy line loss in the previous hour;

[0094] S25. Line loss exceeding limit event determination: The controller determines whether the line loss rate of the current line is greater than the line loss alarm threshold. If so, it determines that a line loss exceeding limit event has occurred, records and immediately reports the event to the upstream device, and executes step S26. If not, it executes step S27. The present invention does not specifically limit the setting of the line loss alarm threshold. A threshold commonly used in the art can be used, and can also be flexibly set according to different line types.

[0095] S26. Line loss recovery event determination: The controller determines in real time whether the current line loss rate is lower than a line loss recovery threshold. If so, it determines that a line loss recovery event has occurred, records the abnormal recovery, and reports it to the upstream device, executing step S27. If not, it executes step S27. The setting of the line loss recovery threshold is not specifically limited in the present invention and can be specifically set according to the site conditions.

[0096] S27. Line loss freezing at the hour: the sensing terminal executes steps S21 to S25 at every hour to obtain and generate hourly line loss freezing data for this line for 24 hours.

[0097] Residual current refers to the current in a low-voltage distribution line where the vector sum of the currents in each phase (including the neutral) is non-zero. Generally speaking, when an accident occurs on the power supply side, current flows from the charged object through the human body to the ground, causing the currents in the main circuit's input and output lines to be unequal to those in the neutral line. The instantaneous vector sum of the currents is called residual current, commonly known as leakage current.

[0098] The detection operation for the residual current over-limit and recovery event in step S2 specifically includes:

[0099] S201, the residual current sampler detects the residual current in the terminal line of the substation in real time, and sends the detected residual current to the meter in real time, and the meter sends the detected residual current to the metering manager;

[0100] S202, the metering manager determines whether the detected residual current is greater than the over-limit value and the duration is greater than the first recovery time. If so, it is determined that the residual current over-limit event persists and step S203 is executed; if not, step S201 is executed;

[0101] S203, storing the residual current exceeding limit event in the second memory, and sending the residual current exceeding limit event to the controller, the controller sending the residual current exceeding limit event to the server, and executing step S204;

[0102] S204, the metering manager determines whether the detected residual current is less than or equal to the return current and the duration is greater than the set second recovery time. If so, it is determined that the over-limit event has disappeared and the substation line has returned to normal, and step S205 is executed; if not, step S203 is executed;

[0103] S205: Send the line restoration information to the controller. The controller sends the line restoration information to the server, and then execute step S201.

[0104] When the residual current transformer 251 detects that the residual current in the line exceeds the over-limit threshold and lasts longer than a preset first recovery time, it determines that an over-limit event has occurred in the line. The over-limit threshold is preferably 50% of the rated current, which is determined based on the specific site implementation and is typically 100A, 200A, or 400A. The first recovery time is 1 minute.

[0105] When an over-limit event occurs, the residual current transformer 251 detects that the residual current in the line is less than or equal to the return current and lasts longer than a set second recovery time, then the over-limit event is considered to have returned to normal. The return current is preferably 30% of the rated current, and the second recovery time is preferably 1 minute.

[0106] In summary, the present invention provides the following advantages:

[0107] (1) The present invention adopts a customized amorphous or Permalloy material external split-type current transformer with high precision, which can meet the current sampling precision level of 0.5, excellent performance, wide operating temperature range, and the ambient operating temperature can be between -40°C and 85°C, and strong anti-interference ability.

[0108] (2) The uplink communication of the present invention supports multiple communication modes, including RS485 communication and external communication modules. The external communication module is pluggable, and its strong and weak current interface definition meets the weak current interface pin definition of the communication module in Chapter A7.3 and the carrier coupling interface definition of the communication module in Chapter A7.4 of "QGDW 1375.3-2013 Electric Power User Electricity Consumption Information Collection System Type Specification Part 3: Collector Type Specification". Since it adopts the standard interface of the State Grid Electric Power Collection System Type I collector, it supports hot plugging and interchangeability, and thus can meet the interchangeability requirements of modules with the same function from different manufacturers. The external communication module can support narrowband, micro-power wireless, HPLC high-speed carrier and HPLC wireless dual-mode communication modes by replacing different communication modules.

[0109] (3) The present invention has an external AC 220V strong current sensing interface, which can be used to monitor the circuit breaker status behind a single user's electricity meter and accurately monitor the user's power-off and power-on status.

[0110] (4) The terminal of the present invention adopts Beidou & GPS dual-mode modules, which can achieve high reliability and high precision positioning of the device's geographic location information.

[0111] (5) The terminal interface of the present invention is rich and has strong expansion performance, which can quickly realize functional transformation and business adjustment in a low-cost manner.

[0112] (6) The present invention realizes residual current monitoring by adopting a multifunctional high-precision three-phase electric energy dedicated metering chip, and has the functions of residual current monitoring and over-limit event reporting.

[0113] (7) The present invention cannot realize the high-frequency collection of 5-minute line operation status data and 15-minute electricity meter load data of the terminal power grid, and cannot combine the terminal meter box metering data with the electricity meter metering data to perform meter box line loss analysis and calculation, realize local perception of meter box line loss and electricity theft analysis decision and upload to the upper terminal and main station.

[0114] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for monitoring the state of a distribution line by a distribution line terminal sensing terminal, characterized in that: Including steps: S1. The sensing terminal receives detection data from the AC strong current sensor and the cross-collection meter in the terminal line, as well as data from multiple connected electric energy meters, generates line operation data, stores the data in a first memory, and waits for reading by the upper device; the line operation data includes real-time cross-collection data of the distribution line, line voltage qualified statistical data, 5-minute accuracy curve data of the distribution line, 15-minute accuracy curve data of all connected electric energy meters, hourly frozen data of the distribution line, daily frozen data of the distribution line, and hourly frozen data of the distribution line loss; the electric energy meter data includes hourly frozen data of the electric meter and daily frozen data of the electric meter; S2. The sensing terminal analyzes and processes the line operation data to determine whether there are any abnormal events in the substation line. When an abnormality occurs, the sensing terminal actively reports the abnormality to the upper-level equipment; the abnormal events include line loss exceeding the limit and recovery events, distribution line power outage and recovery events, voltage exceeding the limit and recovery events, voltage loss and recovery events, current loss and recovery events, three-phase current imbalance and imbalance recovery events, residual current exceeding the limit and recovery events, and line impedance exceeding the limit and recovery events; In step S2, the line loss exceeding limit and recovery event detection specifically includes: S21. Calculate the current hourly line loss: Subtract the sum of the total forward active energy data in the hourly frozen data of all connected electric energy meters from the total forward active energy data in the hourly frozen data of the distribution line on the sensing terminal to obtain the current hourly total forward active energy line loss data of the line; S22. Calculate the incremental line loss data for the previous hour: Subtract the total forward active energy line loss for the previous hour from the total forward active energy line loss for the current hour to obtain the incremental line loss data for the total forward active energy line loss for the current hour. S23, calculating the incremental total forward active electric energy of the line in the previous hour: subtracting the current total forward active electric energy frozen at the previous hour of the sensing terminal from the current hourly total forward active electric energy data in the hourly frozen data of the distribution line of the sensing terminal, to obtain the incremental total forward active electric energy data of the line in the previous hour; S24. Calculate the terminal line loss rate: The terminal line loss rate calculation formula is: ； Wherein, R is the line loss rate in the previous hour; △S is the total forward active energy increment of the line in the previous hour; Sn is the total forward active energy data of the current hour of the sensing terminal; Sn-1 is the total forward active energy frozen at the hour of the previous hour of the sensing terminal; △E is the line loss increment of the total forward active energy in the previous hour; En is the line loss of the total forward active energy in the current hour; En-1 is the line loss of the total forward active energy in the previous hour; S25. Line loss exceeding limit event determination: The controller determines whether the current line loss rate is greater than the line loss alarm threshold. If so, it determines that a line loss exceeding limit event has occurred, records and immediately reports the event to the uplink device, and executes step S26. If not, it executes step S27. S26. Line loss recovery event determination: The controller determines in real time whether the current line loss rate is lower than the line loss recovery threshold. If so, it determines that a line loss recovery event has occurred, records the abnormal recovery, and reports it to the upstream device. If not, proceed to step S27. S27, line loss freezing at the hour: the sensing terminal executes steps S21 to S25 at every hour to obtain and generate hourly line loss freezing data for the line for 24 hours; The perception terminal includes: the controller, the positioning device, the uplink communicator, the downlink communicator, the AC strong current sensor, the cross-collection meter and the first memory; the positioning device, the uplink communicator, the downlink communicator, the AC strong current sensor and the cross-collection meter are respectively connected to the controller; the perception terminal is connected to the uplink device through the uplink communicator and is connected to multiple electric energy meters through the downlink communicator; the memory is connected to the controller; The cross-collection meter includes: a meter manager, a meter, a three-phase voltage sampler, a three-phase current sampler, a residual current sampler, and a second memory; the three-phase voltage sampler, the three-phase current sampler, and the residual current sampler are respectively connected to the meter; the meter and the memory are respectively connected to the meter manager; and the meter manager is connected to the controller.

2. The method for monitoring the state of a distribution line by a distribution line terminal sensing terminal according to claim 1, characterized in that: The three-phase voltage sampler includes a phase A voltage sampling unit, a phase B voltage sampling unit, and a phase C voltage sampling unit; the phase A voltage sampling unit, the phase B voltage sampling unit, and the phase C voltage sampling unit all use the same voltage acquisition unit to respectively collect voltage data in the three-phase line; The voltage sampling unit includes a voltage terminal, an overvoltage protection circuit, a current limiting voltage divider, a voltage transformer, a voltage resistance sampling circuit and a voltage filtering circuit which are connected in sequence; the voltage filtering circuit is connected to the meter.

3. The method for monitoring the state of a distribution line by a distribution line terminal sensing terminal according to claim 1, characterized in that: The three-phase current sampler includes a phase A current sampling unit, a phase B current sampling unit, and a phase C current sampling unit; the phase A current sampling unit, the phase B current sampling unit, and the phase C current sampling unit all use the same current sampling unit to respectively collect current data in the three-phase circuit; The current sampling unit includes an external current transformer, a current terminal, a current resistance sampling circuit, and a current filter circuit connected in sequence; The current filter circuit is connected to the meter.

4. The method for monitoring the state of a distribution line by a distribution line terminal sensing terminal according to claim 1, characterized in that: The residual current sampler includes a residual current transformer, a residual current terminal, a residual current resistance sampling circuit, and a residual current filter circuit which are connected in sequence; the residual current filter circuit is connected to the meter.

5. The method for monitoring the state of a distribution line by a distribution line terminal sensing terminal according to claim 1, characterized in that: The AC strong current sensor includes an AC strong current overvoltage protector, an AC strong current limiter, an optical coupler reverse protection device and an AC strong current isolator which are connected in sequence; the AC strong current isolator is connected to the controller.

6. The method for monitoring the state of a distribution line by a distribution line terminal sensing terminal according to claim 1, characterized in that: The step S1 specifically includes: S11, the meter collects in real time the three-phase voltage data detected by the three-phase voltage sampler, the three-phase current data detected by the three-phase current sampler, and the residual current data detected by the residual current sampler, and updates them to the metering manager at a predetermined frequency; S12. The metering manager obtains active power data of the distribution area based on the three-phase voltage data and the three-phase current data, thereby obtaining electric energy data, and stores the active power data and the electric energy data in the second memory; S13, the controller obtains the three-phase voltage data, three-phase current data, active power data, and electric energy data from the metering manager at a first predetermined interval, and generates operation data of the current line by combining the operation data of each electric energy meter obtained by the controller from all connected electric energy meters; S14. The controller stores the line operation data in the first memory and waits for the upstream device to read it.

7. The method for monitoring the state of a distribution line by a distribution line terminal sensing terminal according to claim 1, characterized in that: The detection operation for the residual current over-limit and recovery event in step S2 specifically includes: S201, the residual current sampler detects the residual current in the terminal line of the substation in real time, and sends the detected residual current to the meter in real time, and the meter sends the detected residual current to the metering manager; S202, the metering manager determines whether the detected residual current is greater than the over-limit value and the duration is greater than the first recovery time. If so, it is determined that the residual current over-limit event persists and step S203 is executed; if not, step S201 is executed; S203, storing the residual current exceeding limit event in the second memory, and sending the residual current exceeding limit event to the controller, the controller sending the residual current exceeding limit event to the server, and executing step S204; S204, the metering manager determines whether the detected residual current is less than or equal to the return current and the duration is greater than the set second recovery time. If so, it is determined that the over-limit event has disappeared and the substation line has returned to normal, and step S205 is executed; if not, step S203 is executed; S205: Send the line restoration information to the controller. The controller sends the line restoration information to the server, and then execute step S201.

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