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Remote Terminal Unit-RTU

BD-163 distribution automation remote terminal (hereinafter referred to as the distribution terminal) is a new generation of power distribution terminal based on the latest generation of automated remote terminal technology. 


Remote terminal UNIT-RTU is a general term for various remote monitoring and control units installed in the distribution network, which has functions such as data collection, control, and communication. The power distribution terminal is the eyes and limbs of the power distribution automation system. The operating status of RTU in SCADA system is related to the data reliability, performance accuracy and operational safety of the power distribution automation. When the configuration is correct and the operation is normal, the RTU system realizes the correct operation of switches, rapid fault isolation and power restoration, thereby improving power supply reliability.


Technical Parameters of RTU Unit



Types of Remote Terminal Unit


Features of Remote Terminal Unit-RTU


  • With "communication", the RTU system has a "remote maintenance" function.

  • Flexible configuration, all protection functions have a separate retreat.

  • The RTU in SCADA system has a complete self-checking function to detect the working conditions of each part online.

  • The closing and closing circuit adopts an anti-misoperation design and has an anti-missing function.

  • Applicable to analog acquisition, state quantity acquisition, local and remote control switch closing of 4-12 switch.

  • 24 channels can be controlled by expansion.

  • By selecting different configurations, remote terminal unit can meet the needs of “Three Remote” and “Two Remote” of the State Grid and South Grid.

  • Meet the special requirements of all parts of the country (such as Shandong, Beijing, Guangdong, etc.)

  • Zero-sequence current setting adaptive function, no manual setting required.

  • Meet the specific requirements of “one or two integration".

  • The core RTU unit can be flexibly configured to shade vertical, shaded horizontal, outdoor vertical, an d group screen.


Technical parameters of Remote Terminal Unit-RTU:


Ac sampling

Electromagnetic transformer

Measuring voltage range

0~200V(Un=100V)

ratio (10KV//0.1KV/

Measuring zero-sequence voltage range

0~200V(Un=100V/3)

ratio (10KV//0.1KV/

Measuring current range

0.01~1.2A(In=1A)或0.01~6A(In=5A)

Precision grade of measuring voltage and current

Class 0.5

Protective current range

0~100A( In=5A)/0~20A( In=1A)

Protective current accuracy

±3%

Active power precision class

Class 0.5

Reactive power accuracy class

Class 1

Power factor resolution

0.001

Frequency measurement range

45~55Hz

Frequency measurement error

<0.01Hz

Electronic transformer

Measuring voltage range

0~6.5V(Un=3.25V/V)

ratio (10KV//3.25V/

Measuring zero-sequence voltage range

0~13V(Un=6.5V/3V)

ratio (10KV//6.5V/3V

Measuring current range

0~20V(In=1V)        ratio 600A/1V

Measuring zero-sequence current range

0~2V(In=0.2V)        ratio 20A/0.2V

Precision class of measuring voltage and current

Class 0.5

Protective current range

0~20V(In=1V)        ratio 600A/1V

Protective current accuracy

±3%

Zero sequence voltage/zero sequence current accuracy level

Class 0.5

Active power precision class

Class 0.5

Reactive power accuracy class

Class 1

Power factor resolution

0.001

Frequency measurement range

45~55Hz

Frequency measurement error

<0.01Hz



Remote Terminal Unit-RTU Function

Distribution Terminal Unit-DTU installation location: indoor and outdoor opening and closing station, power distribution room, knife lock chamber, box change, switch,it can detect line fault and overload status function, and can detect line zero sequence overvoltage, zero sequence overcurrent, line overload, line overcurrent, phase-to-phase short circuit protection, etc. It can be flexibly set to alarm and trip action. And record the fault event.


The main functions of the RTU in SCADA system are

  • Realize comprehensive coverage and monitoring of the operating conditions of power distribution terminals, and quickly retrieve and locate each terminal through the terminal list column;

  • Realize remote monitoring of distribution terminal channel working conditions and board status, and timely alert terminal equipment defect information through the event warning window;

  • Realize the remote query of the fixed value setting of the SCADA in electrical power system, the content of the information table and the program version, and complete the program upgrade, the fixed value placement, and the modification of the information table remotely through the remote setting bar;

  • Realize the remote query and download of the information in the memory of the power distribution terminal, such as remote signal displacement, over-current alarm, remote control operation record and other local information.


How RTUs System Gather Information

The remote operation and maintenance system of the RTU in SCADA system is composed of a communication management server, a Web server, network security protection equipment, and a maintenance workstation: the communication management server is used to provide direct communication with remote terminals and collect status information and parameter information of each remote terminal. The data gathered by remote terminal unit in SCADA is forwarded to the web server according to the data requested by the web server, and the terminal parameter setting command issued by the webserver is forwarded to the terminal; the web data server is used to provide a high-performance network service to provide users with browsing and modifying terminal parameters and status The interface also displays terminal real-time letter and wish data, and realizes various functions of human-computer interaction. 


Comparison to Other Devices

RTU is the basic unit of SCADA system, which is an electronic device installed on a remote site to monitor, measure and collect sensors and equipment installed on a remote site. PLC is a programmable logic controller, which performs data collection and instruction processing in the field station. Compared with the PLC, there are three main advantages: 1.RTU is generally not restricted by the geographical environment and can be installed near the outdoor on-site measurement point. 2. Since RTU is not restricted by the working environment, its technical specifications are required to meet harsh environment requirements and specific requirements. Its data storage capacity is large, the analog quantity acquisition ability is strong (up to 24 channels), and the analog function is far more powerful than PLC. 3. The RTU communication function is powerful. It will finally transmit the collected analog, switch, and digital information to the dispatch center, and the dispatch center is sometimes thousands of miles away, it is required to have a remote communication function. Although PLC also has a communication function, it is limited to the short-distance transmission of data within the plant station, and its communication function is slightly inferior to that of RTU.