https://zhuanlan.zhihu.com/p/2010735156437222849
As a professional provider of IoT data acquisition solutions and an expert in industrial IoT data acquisition, the editor of Shanghai Data Acquisition IOT Technology Co., Ltd， (daq-iot) hereby presents the following introduction, and sincerely welcomes discussions and exchanges.
Supported Communication Interfaces: CAN, RS485, Mbus, 4–20mA, Profibus, CC-Link, HART, digital I/O, etc.
Industrial Protocols: Modbus RTU/TCP, HJ212, IEC104, DLT645, DLMS, IEC61850, MQTT, etc.
Mail:export@daq-iot.com
1.1 Low voltage distributed PV Protocol conversion system power distributed photovoltaic information acquire system
The low-voltage distributed PV Protocol conversion system is a system that collects, processes, and monitors the power generation and consumption information of PV users, achieving functions such as automatic collection of PV user information, abnormal measurement monitoring, power quality monitoring, power analysis and management, related information release, distributed energy monitoring, and information exchange of intelligent power equipment.
1.2 Electricity information collection terminal electric energy data acquire terminal
The electricity information collection terminal is a device that collects electricity information from various information collection points, abbreviated as the collection terminal. A device that can collect, manage, transmit data bidirectionally, and forward or execute control commands for electric energy meter data. Electricity information collection terminals are divided into specialized transformer collection terminals, centralized meter reading terminals (including concentrators and monitoring units), distributed energy monitoring terminals, and other types according to their application locations.
1.3 Distributed PV inverter dedicated communication interface adapter photovoltaic Inverter communication interface converter
The distributed PV inverter dedicated communication interface adapter (hereinafter referred to as the "adapter") is an accessory for connecting the monitoring unit to the PV inverter. Each monitoring unit is paired with an adapter to connect thePVinverter circuit. Used to implement a single inverter power consumption information acquisition system and switch between dual master station communication on the manufacturer's cloud platform. Expand the original communication 485 channel of the inverter into two channels, with one channel ensuring that the manufacturer's cloud platform communication is not affected, and the other 485 channel connected to the monitoring unit, enabling both main stations to collect and issue control commands normally.
2 Structural requirements
2.1 Appearance of Monitoring Unit
The external structure, dimensions, installation dimensions, wiring terminals, communication interfaces, and identification marks of the monitoring unit shall comply with the requirements specified in this section. The external dimensions (length, width, height) of the monitoring unit shall not exceed 100mm × 65mm × 70mm, and the specific dimensions shall be subject to the actual needs of the user after winning the bid.
2.2 Shell and its protective performance
2.2.1 Mechanical strength
The casing of the monitoring unit should have sufficient strength, and deformation caused by external impact should not affect its normal operation.
2.2.2 Flame retardant performance
Non metallic shells shall comply with the flame retardant requirements of GB/T 5169.11-2006.
2.3 Wiring terminals
The external connection wires of the monitoring unit should pass through the wiring terminals, and the wiring terminals and their insulation components can form a terminal block; The strong and weak electrical terminals are arranged separately, with effective insulation isolation; The structure of the voltage output terminal should be compatible with the lead wire with a cross-sectional area of 1.5 mm2 to 2.5 mm2; The structure of other weak current outgoing terminals should be compatible with outgoing wires with a cross-sectional area of 0.5 mm2 to 1.5 mm2.
The minimum electrical clearance and creepage distance of the terminal block shall comply with the requirements of 4.6 of this section, and the flame retardant performance of the terminal block shall comply with the flame retardant requirements of GB/T 5169.11-2006.
2.4 Wiring diagram and identification
The monitoring unit is engraved with a wiring terminal diagram on the bottom of the upper shell.
2.5 Corrosion Protection of Metal Parts
Metal parts that may be corroded or rust prone under normal operating conditions should have anti rust and anti-corrosion coatings or coatings.
2.6 Electrical clearance and creepage distance
The exposed live parts should have the minimum electrical clearance and creepage distance specified in Table 1 between the ground and other live parts, as well as between the outgoing terminal screws and the metal cover plate. The electrical clearance of monitoring units working at an altitude of over 2000m should be corrected according to the provisions of GB/T 16935.1-2008.
Table 1 Minimum electrical clearance and creepage distance
| | | |
| --- | --- | --- |
| Rated voltage V | Electrical clearance mm | Creepage distance mm |
| U≤25 | 1 | 1.5 |
| 25＜U≤60 | 2 | 2 |
| 60＜U≤250 | 3 | 4 |
| 250＜U≤380 | 4 | 5 |
3 Technical Requirements
3.1 Classification
The classification of monitoring unit type identification codes is shown in Table 5.
Table 5 Classification Explanation of Monitoring Unit Type Identification Codes
| | | | | | |
| --- | --- | --- | --- | --- | --- |
| DG | X | X | X | X | -XXXX |
| Classification of monitoring units | Uplink communication channel | I/O configuration/downlink communication channel | temperature level | Product Code |
| DG - PV Acquisition Protocol Converter | D - dual-mode J - Micro power wireless Z—Power line carrierQ - Other | Downstream communication channel: J-low-power wireless Z-power line carrier L-wired network | 1-9-1-9 485 interfaces, A-W-10-32 energy meter interfaces | 1－C12－C23－C34－CX | Composed of no more than 8 English letters and numbers. English letters can be represented by the Pinyin abbreviation of the production enterprise name, and numbers represent the product design serial number |
3.2 Recommended Types for Selection
The uplink communication channel can use power line carrierRS-485 busThe downlink channel can use RS-485 bus, which can be connected to onePVinverter, and the temperature can be set to C3 level.
3.3 Environmental conditions
3.3.1 Reference Temperature and Reference Humidity
The reference temperature is 23 ° C, with an allowable deviation of ± 2 ° C; The reference humidity is between 40% and 60%.
3.3.2 Temperature and humidity range
The climate and environmental conditions for the normal operation of the monitoring unit should meet the requirements of Table 6.
Table 6 Classification of Climate and Environmental Conditions
| | | | |
| --- | --- | --- | --- |
| venue type | level | Air temperature | Humidity |
| Range ℃ | Maximum rate of change a ℃/h | Relative humidity b% | Maximum absolute humidity g/m3 |
| shelter | C1 | -5～+45 | 0.5 | 5～95 | 29 |
| C2 | -25～+55 | 0.5 | 10～100 |
| Outdoor | C3 | -40～+70 | 1 | 35 |
| Protocol Specific | CX | | | | |
| The temperature change rate is taken as the average value within 5 minutes. Relative humidity includes condensation. |
3.3.3 Atmospheric pressure
It should be able to operate normally under environmental conditions with atmospheric pressure ranging from 63.0 kPa to 108.0 kPa (altitude of 4000 m and below), without affecting its function, except for special ordering requirements.
3.4 Temperature rise
Under rated operating conditions, the circuit and insulation should not reach temperatures that may affect the normal operation of the monitoring unit, and the temperature rise on the outer surface should not exceed 25 K at an ambient temperature of 40 ℃.
3.5 Insulation performance
3.5.1 Insulation resistance
The insulation resistance between each electrical circuit of the monitoring unit and the ground and between each electrical circuit should meet the requirements in Table 2.
Table 2 Insulation resistance requirements for each electrical circuit of the monitoring unit to ground and between each electrical circuit
| | | | | |
| --- | --- | --- | --- | --- |
| | Rated insulation voltage (U) V | Insulation resistance M Ω | Test voltage V | |
| | normal conditions | Damp and hot conditions | |
| | U≤60 | ≥10 | ≥2 | 250 | |
| | 60＜U≤250 | ≥10 | ≥2 | 500 | |
| | U＞250 | ≥10 | ≥2 | 1000 | |
3.5.2 Insulation strength
Each electrical circuit of the monitoring unit should withstand an AC voltage of 50 Hz as specified in Table 3, and undergo an insulation strength test for 1 minute between the ground and each electrical circuit. During the experiment, there should be no breakdown or flashover, and the leakage current should not exceed 5 mA.
Table 3 Voltage for Insulation Strength Test
| | |
| --- | --- |
| Technical Requirements | Test Plan |
| Leakage current ≤ 5mA, applied for 1 minute, with no breakdown, flashover, or damage to the terminal during the test. After the experiment, the terminal can work normally and the Data Acquisition function meets the requirements. | Test circuit | Test voltage (V) | Leakage current (mA) |
| Power supply to RS-485 interface | 4000 | ≤5mA |
| Power supply to ground | 2000 | ≤5mA |
| RS-485 interface to ground | 500 | ≤5mA |
3.5.3 Impulse voltage
Each electrical circuit of the monitoring unit should withstand the peak impulse voltage specified in Table 4, with 5 positive and 5 negative polarities, between the ground and non electrically connected circuits. There should be no destructive discharge (breakdown, flashover, or insulation breakdown) during the experiment.
Table 4 Peak Value of Impulse Voltage
| | |
| --- | --- |
| Test circuit | Test voltage (V) |
| Power supply to ground | 5000 |
| Between the power supply and RS-485 interface | 6000 |
| RS-485 interface to ground | 2000 |
3.6 Electrical clearance and creepage distance
The exposed live parts should have the minimum electrical clearance and creepage distance specified in Table 5 between the ground and other live parts, as well as between the outgoing terminal screws and the metal cover plate. The electrical clearance of monitoring units working at an altitude of over 2000m should be corrected according to the provisions of GB/T 16935.1-2008.
Table 1 Minimum electrical clearance and creepage distance
| | | |
| --- | --- | --- |
| Rated voltage (U) V | Electrical clearance mm | Creepage distance mm |
| U≤25 | 1 | 1.5 |
| 25＜U≤60 | 2 | 2 |
| 60＜U≤250 | 3 | 4 |
| 250＜U≤380 | 4 | 5 |
3.7 Mechanical Effects
The monitoring unit should be able to withstand mechanical vibrations and impacts under normal operation and conventional transportation conditions without causing failure or damage.
3.8 Working power supply
The monitoring unit uses AC single-phase power supply, and the AC magnetic flux density generated during operation is less than 0.5 mT.
The rated voltage of the working power supply is 220 V, with an allowable deviation of -20% to+50%; The frequency is 50 Hz, with a permissible deviation of -6% to+2%.
3.9 Power consumption
The apparent power consumed by the monitoring unit in non communication state should not exceed 5VA, and the active power should not exceed 2W; the apparent power consumed in communication state should not exceed 8VA, and the active power should not exceed 3W.
3.10 Power loss data and clock retention
After the power supply of the monitoring unit is interrupted, there should be no misreading of data. The stored data should be saved for at least 10 years, and the clock should run normally for at least 48 hours. When the power is restored, the saved data should not be lost, and the internal clock should run normally. The absolute value of the clock's daily timing error is ≤ 0.5 s/d, and the clock is running normally.
3.11 Overvoltage resistance capability
The monitoring unit should have the ability to withstand 1.9 times the nominal voltage input.
3.12 Anti grounding fault capability
When the power supply of the monitoring unit is supplied by a three-phase four wire distribution network that is not effectively grounded or has a neutral point that is not grounded, in the event of a ground fault and a relative overvoltage of 10%, the voltage between the two ungrounded phases will reach 1.9 times the nominal voltage; In this case, the monitoring unit should not be damaged. After the power supply is restored to normal, the monitoring unit should work normally and the saved data should remain unchanged.
3.13 Main Performance Indicators
The CPU frequency of the monitoring unit shall not be less than 32 MHz, and the memory shall not be less than 32 kByte.
3.14 Electromagnetic compatibility requirements
The monitoring unit should be able to withstand conducted and radiated electromagnetic disturbances as well as the effects of electrostatic discharge, and the equipment should be undamaged and able to function normally.
The electromagnetic compatibility test items include voltage sag and short interruption, power frequency magnetic field immunity, radio frequency electromagnetic field radiation immunity, radio frequency induced conducted disturbance immunity, electrostatic discharge immunity, electrical fast transient pulse group immunity, damping oscillation wave immunity, surge immunity, and radio interference suppression.
The test levels and requirements are shown in Table 7.
Table 7 Test Levels and Requirements for Electromagnetic Compatibility Testing
| | | | |
| --- | --- | --- | --- |
| Test Project | Level | Experimental value | Test circuit |
| Power frequency magnetic field immunity | / | 400A/m | complete machine |
| Radio frequency radiation electromagnetic field immunity | 3/4 | 10V/m（80MHz～1000MHz）30V/m（1.4GHz～2GHz） | complete machine |
| Electrostatic discharge immunity | 4 | Contact discharge 8kV, air discharge 15kV | Terminal/shell |
| Electrical fast transient burst immunity | | 2.0kV (coupled) | RS-485 |
| 4 | 4.0kV | power circuit |
| Damping oscillation wave immunity | 2 | 1.0kV (common mode) | RS-485 |
| 3 | 2.5kV (common mode) 1.25kV (differential mode) | power circuit |
| Surge immunity | 3 | 1.0 kV (common mode) | RS-485 interface |
| 4 | 4 kV (common mode) | power circuit |
| 2 kV (differential mode) |
| Voltage sag and short-term interruption | / | Voltage sag: 60%; Duration: 1 minute, once; Short term interruption: 0%: Duration: 1s, 50 cycles, Interruption frequency: 3 times, | complete machine |
| Immunity to Conducted Disturbances Induced by Radio Frequency Fields | 3 | 10V/m (non modulated) | Power supply terminal and protective grounding terminal |
3.15 Continuous power on stability
The monitoring unit shall be continuously powered on for 72 hours in normal working condition, and sampling tests shall be conducted every 8 hours during the 72 hour period. Its functions and performance shall meet relevant requirements.
3.16 Reliability indicators
The mean time between failures (MTBF) of the monitoring unit shall not be less than 7.6 × 104 hours.
6 Communication interfaces
6.1 Communication Method
The communication unit interface of the monitoring unit should adopt a modular structure design and meet the requirement of interchangeable communication modules.
- The uplink communication method supports dual-mode (HPLC+HRF) and supports hot plugging.
- The downlink communication method supports the use of RS-485.
- Maintain channel support using Bluetooth RS-485， Bluetooth should meet BLE 5.0 or above requirements. 6.2 Communication speed
- The default baud rate for communication between the monitoring unit and the dual-mode module is 9600bps, with a maximum support of 115200bps. The communication rate can be set, and the verification method is even verification, with 8-bit data bits and 1-bit stop bits.
- At least 2 RS-485 local communication interfaces should be available, and the RS-485 I interface should support adaptive communication for both uplink and downlink; The default baud rate for RS-485 interface communication is 9600bps, with no checksum, 8-bit data bits, and 1-bit stop bits. It can adapt to the speed of the inverter 485 interface and achieve automatic serial port matching.
- The default baud rate for maintaining RS-485 interface communication is 9600bps, with even parity, 8-bit data bits, and 1-bit stop bits. As a maintenance interface, it supports a maximum of 115200bps. 6.3 Communication Protocol
- The upstream communication of the monitoring unit Protocol should support DL/T698.45 and its extensions Protocol.
- The downlink communication of the monitoring unit Protocol should support all PV inverter manufacturers in operation in Tianjin, including Jinlang, Hewang, Guriwatt, Gudewei, Huawei, Outai, Aisiwei, Sunac, Chint, Tianhe, Sanjing, Shouhang, Skyworth, Maoshuo, Shangneng, Magreeneng, Envision, Coaster, TBEA, Linuo Power, etcModbusProtocol。 6.4 Interchangeability Requirements The monitoring unit can be matched with the dual-mode communication unit to complete various functions of Data Acquisition. The monitoring unit should meet the following requirements: a) The duration of the low-level reset signal of the distributed power access unit shall not be less than 200ms; b) The response time for direct interaction commands between the distributed power access unit and the communication unit shall not exceed 6 seconds; c) The command response time between the distributed power access unit and the communication unit through channel interaction shall not exceed 90 seconds; d) The dual-mode communication unit interface of the distributed power supply access unit is connected to a 96 Ω pure resistive load with a 12V power output interface. The output voltage should be between 11V and 13V to ensure the normal operation of the communication unit. 6.5 Data Encryption Monitoring unit configurationESAM chipIt is compatible with both hard encryption and soft encryption methods for data encryption, and supports communication data encryption through software remote and local upgrade methods. 7 Functional Requirements 7.1 AC voltage sampling The distributed power access unit should have voltage sampling function, with a measurement accuracy of 1.0 level for voltage. 7.2 Parameter Setting and Query Function
- The monitoring unit should be able to maintain port settings and query parameters, including clock, address, etc. Support remote or handheld device parameter settings and queries for the main station.
- The monitoring unit should have a timing unit, and the daily timing error of the timing unit should be absolute
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