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Publication time：2019-09-18
01
FTU
1.1
define
FTU is a switch monitoring device installed next to the feeder switch. These feeder switches refer to outdoor pole mounted switches, such as circuit breakers, load switches, section switches, etc. on 10kV lines. Generally speaking, one FTU is required to be able to monitor one pole mounted switch. The main reason is that pole mounted switches are mostly installed in a scattered manner. If they are installed on the same pole, one FTU can monitor two pole mounted switches.
1.2
characteristic
FTU adopts advanced DSP digital signal processing technology, multi CPU integration technology, high-speed industrial network communication technology, and an embedded real-time multitasking operating system. It has strong stability, high reliability, good real-time performance, wide adaptability to environments, and powerful functions. It is a new generation of feeder automation remote terminal device that integrates telemetry, remote signaling, remote control, protection, and communication functions. Suitable for automation engineering of urban, rural, and enterprise distribution networks, it completes automation functions such as monitoring, control, and protection of ring main units, pole mounted switches, and communication. Cooperate with the power distribution station and main station to achieve normal monitoring and fault identification, isolation, and restoration of power supply to non faulty sections of the distribution line.
1.3
function
telemetry
(1) Communicating electrical measurements
Any combination of Ia, Ib, Ic, In, Uab, Ucb, Ua, Ub, Uc, Un, etc., usually Uab and Ucb are taken on both sides of the switch to monitor the power supply situation at both ends of the feeder.
(2) Two table method or three table method, the software calculates P, Q, Pa, Pb, Pc, f, cos ∧, etc., and uploads them according to the needs of the main station;
(3) Protect the upload of records for Ia and Ic;
(4) DC analog quantity: two channels, battery voltage, temperature, etc.
remote signaling
(1) Switch status signal, SOE;
(2) Switching energy storage signal, operating power supply;
(3) Pressure signals, etc;
(4) Battery low voltage alarm;
(5) Protect actions and abnormal signals;
(6) Other status signals.
remote control
(1) The switch can be opened and closed at least twice after power failure;
(2) Maintenance of batteries;
(3) Protection signal remote reset;
(4) Other remote controls.
Data transmission function
Capable of communicating with the superior station, sending and receiving control commands from the superior station for the collection and processing of information.
During school hours with superiors.
Forward information from other terminals upwards.
Forward electrical energy information upwards.
Proactively upload accident information (optional function).
Having a locally maintained communication interface.
Communication protocol: Supports various communication protocols such as DL/T 634.5101-2002 (IEC60870-5-101), DL/T 634.5104-2002 (IEC60870-5-104), DL/T 451-91 cyclic telecontrol protocol, DNP3.0, SC1801, MODBUS, etc., and can be expanded as needed.
Communication interface: RS-232/485, Industrial Ethernet, CAN.
Communication channel: It can support various communication forms such as fiber optic, carrier wave, wireless spread spectrum, wireless data transmission radio, CDMA, GPRS, and ADSL, which can be selected by users.
Fault identification, isolation, power restoration, and protection
It has the functions of quick break, delayed overcurrent (composite low voltage) protection, and reclosing, and can be selected according to the feeder automation scheme.
Monitor the fault current, record the overcurrent time and maximum overcurrent value, and report to the distribution substation and main distribution station.
Based on the overcurrent fault information and switch tripping information reported by each switch FTU, the distribution substation and main station determine the fault area according to the dissipative topology model of the distribution network, identify the fault area, generate fault isolation command sequence and non fault area restoration power supply command sequence. Automatic or human-machine interactive execution.
On site operation
There are opening and closing buttons inside the FTU for on-site operation.
There are local/remote selection switches, maintenance discharge buttons, etc.
Ring network function
When FTU is set as the contact switch, the switch is automatically controlled to open and close according to the set value based on the power status of one or both PT sides. When there is electricity on both sides of the switch, it is forbidden to close the contact switch. For those that require network operation, the main station needs to be specifically set up and confirmed. When one side loses power, according to the FA scheme and the settings of the main station, automatic closing is allowed and controlled to quickly restore power supply.
Fixed value download and upload function
Quickly determine the value and enable it;
Overcurrent setting, time constant, enable;
Re closing time and enable;
Setting and canceling the ring network function.
Local maintenance function
Debugging and maintenance are carried out using specialized maintenance software through the standard communication maintenance interface on FTU.
Including parameter setting configuration and inspection; Remote telemetry, remote signaling, remote control, and time synchronization testing; Data uploading, communication, etc.
Self diagnosis and self recovery functions
It has a self diagnostic function, which immediately records and reports any abnormalities in FTUs memory, clock, I/O, etc.
It has a self recovery function when powered on.
Power UPS and battery maintenance function
Meet the power requirements for operating mechanisms, terminal equipment, and communication devices.
FTU dual power supply, can continue to work even after one side of the power supply loses power.
Normally, the FTU is powered by the main power supply, while the battery is float charged. After the bilateral power supply loses power, the FTU can continue to work for 24 hours (except for the radio) powered by the battery.
Battery low voltage alarm protection function.
Battery automatic maintenance: Within the specified time, the dispatcher issues a battery maintenance command, and the battery begins to discharge. When the battery voltage is low, it automatically stops discharging, switches to the main power supply, and charges the battery. The battery charging adopts constant voltage and current limiting charging to ensure safety.
02
Switching station, ring main unit terminal equipment（DTU）
2.1
define
DTUs are generally installed in conventional switch stations, outdoor small switch stations, ring main units, small substations, box type substations, etc., to complete the collection and calculation of position signals, voltage, current, active power, reactive power, power factor, electric energy and other data of switch equipment, perform opening and closing operations on switches, realize fault identification and isolation of feeder switches, and restore power supply to non fault sections.
2.2
characteristic
1) The chassis structure adopts a standard 4U half (full) chassis with enhanced design;
2) Adopting a post plug and unplug wiring method, with an overall panel and fully enclosed design;
3) Taking the lead in adopting an intelligent plugin solution based on CANBUS bus greatly reduces the indirect wiring of plugins, completely avoiding the hidden danger of poor contact of plugins, and ensuring high reliability of device operation;
4) The adoption of intelligent plug-in solutions standardizes the motherboard of the chassis, facilitating production and on-site maintenance;
5) Ensure that different types of plugins cannot be interchanged during structural design to improve overall safety;
6) Adopting 32-bit floating point SP, the system has advanced performance;
7) Adopting a 16 bit A/D conversion chip, with high sampling accuracy;
8) Adopting large-scale programmable logic chips to reduce peripheral circuits and improve reliability;
9) Large capacity storage design enables complete on-site requirements for message and accident recording;
10) Adopting multi-layer printed circuit boards and SMT surface mount technology, the device has strong anti-interference performance;
11) Automatic calibration of measurement circuit accuracy software, no debugging required, reducing maintenance time such as on-site calibration;
12) Strong electromagnetic compatibility capability, able to adapt to harsh working environments;
13) Powerful PC support tools with comprehensive and flexible analysis software, facilitating accident analysis;
14) A simple and reliable protection processing system (DSP) combined with a mature real-time multitasking operating system ensures both functional reliability and meets the real-time requirements of network communication and human-machine interface;
15) Supports multiple communication interfaces such as RS232/RS485, Enthernet, etc. The built-in Enthernet makes engineering applications simple and reliable;
16) Support standard protocols such as IEC60870-5-101, IEC60870-5-103, IEC60870-5-104, etc;
17) Each device has an independent power-off clock system and a GPS timing system with timing pulses.
2.3
function
telemetry
(1) Communicating electrical measurements
Any combination of Ia, Ib, Ic, In, Uab, Ucb, Ua, Ub, Uc, Un, etc., usually Uab and Ucb are taken on both sides of the switch to monitor the power supply situation at both ends of the feeder.
(2) Two table method or three table method, the software calculates P, Q, Pa, Pb, Pc, f, cos ∧, etc., and uploads them according to the needs of the main station;
(3) Protect the upload of records for Ia and Ic;
(4) DC analog quantity: two channels, battery voltage, temperature, etc.
remote signaling
(1) Switch status signal, SOE;
(2) Switching energy storage signal, operating power supply;
(3) Pressure signals, etc;
(4) Battery low voltage alarm;
(5) Protect actions and abnormal signals;
(6) Other status signals.
remote control
(1) The switch can be opened and closed at least twice after power failure;
(2) Maintenance of batteries;
(3) Protection signal remote reset;
(4) Other remote controls.
Data transmission function
Capable of communicating with the superior station, sending and receiving control commands from the superior station for the collection and processing of information.
During school hours with superiors.
Forward information from other terminals upwards.
Forward electrical energy information upwards.
Proactively upload accident information (optional function).
Having a locally maintained communication interface.
Communication protocol: Supports various communication protocols such as DL/T 634.5101-2002 (IEC60870-5-101), DL/T 634.5104-2002 (IEC60870-5-104), DL/T 451-91 cyclic telecontrol protocol, DNP3.0, SC1801, MODBUS, etc., and can be expanded as needed.
Communication interface: RS-232/485, Industrial Ethernet, CAN.
Communication channel: It can support various communication forms such as fiber optic, carrier wave, wireless spread spectrum, wireless data transmission radio, CDMA, GPRS, and ADSL, which can be selected by users.
Fault identification, isolation, restoration of power supply and protection
It has the functions of quick break, delayed overcurrent (composite low voltage) protection, and reclosing, and can be selected according to the feeder automation scheme.
Monitor the fault current, record the overcurrent time and maximum overcurrent value, and report to the distribution substation and main distribution station.
Based on the overcurrent fault information and switch tripping information reported by each switch DTU, the distribution substation and main station determine the fault area according to the dissipative topology model of the distribution network transformer structure, identify the fault area, generate fault isolation command sequence and non fault area restoration power supply command sequence. Automatic or human-machine interactive execution.
On site operation
There are opening and closing buttons inside the DTU for on-site operation.
There are local/remote selection switches, maintenance discharge buttons, etc.
Ring network function
When DTU is set as the contact switch, the switch is automatically controlled to open and close according to the set value based on the power status of one or both PT sides. When there is electricity on both sides of the switch, it is forbidden to close the contact switch. For those that require network operation, the main station needs to be specifically set up and confirmed. When one side loses power, according to the FA scheme and the settings of the main station, automatic closing is allowed and controlled to quickly restore power supply.
Fixed value download and upload function
Quickly determine the value and enable it;
Overcurrent setting, time constant, enable;
Re closing time and enable;
Setting and canceling the ring network function.
Local maintenance function
Debugging and maintenance are carried out using specialized maintenance software through the standard communication maintenance interface on DTU.
Including parameter setting configuration and inspection; Remote telemetry, remote signaling, remote control, and time synchronization testing; Data uploading, communication, etc.
Self diagnosis and self recovery functions
Equipped with self diagnostic function, it immediately records and reports any abnormalities in DTUs memory, clock, I/O, etc.
It has a self recovery function when powered on.
Power UPS and battery maintenance function
Meet the power requirements for operating mechanisms, terminal equipment, and communication devices.
DTU is powered by dual power sources, and can continue to operate even after one side of the power supply loses power.
Usually, the DTU is powered by the main power supply, while the battery is float charged. After the bilateral power supply loses power, the DTU can continue to work for 24 hours (except for the radio) powered by the battery.
Battery low voltage alarm protection function.
Battery automatic maintenance: Within the specified time, the dispatcher issues a battery maintenance command, and the battery begins to discharge. When the battery voltage is low, it automatically stops discharging, switches to the main power supply, and charges the battery. The battery charging adopts constant voltage and current limiting charging to ensure safety.
03
Intelligent distribution transformer terminal equipment（TTU）
3.1
define
TTU monitors and records the operating conditions of distribution transformers. Based on the three-phase voltage and current sampling values on the low voltage side, it calculates the voltage effective value, current effective value, active power, reactive power, power factor, active energy, reactive energy and other operating parameters every 1-2 minutes. It records and saves the hourly values of the above array for a period of time (one week or one month) and typical days, the maximum and minimum values of voltage and current and their occurrence time, power interruption time and recovery time. The recorded data is saved in the non-volatile memory of the device, and the recorded content is not lost when the device is powered off. The main station of the distribution network reads the TTU measurement values and historical records through the communication system at regular intervals, and promptly discovers operational problems such as transformer overload and power outage. Based on the recorded data, it statistically analyzes the voltage qualification rate, power supply reliability, and load characteristics, and provides basic data for load forecasting, distribution network planning, and accident analysis. If communication conditions are not available, use a handheld computer to read records on site every week or month, and then transfer them to the distribution network main station or other analysis systems.
3.2
characteristic
Suitable for monitoring and energy measurement of power supply companies, county-level power companies, power plants, industrial and mining enterprises, military academies, rural township power management stations, 100-500KVA distribution transformers and substations, in conjunction with power consumption supervision for line loss assessment. It can also send all data to the power management center through GPRS communication network, providing the most authentic and accurate decision-making basis for optimizing low-voltage distribution networks.
3.3
function
■ "Four in One" comprehensive function
Integrating four functions: metering, power quality monitoring, distribution transformer condition monitoring, and reactive power compensation.
Intelligent reactive power compensation
Intelligent capacitors can form their own system, with automatic switching of capacitors to achieve automatic reactive power compensation
■ Flexible networking
Following the current distribution monitoring system regulations of State Grid Corporation of China and Southern Power Grid Corporation of China, it is convenient to access the existing load management system and distribution management system of the power enterprise, provide complete real-time voltage and reactive power information, and can also independently form a reactive power real-time information system
■ Simple engineering
The device has a simple structure, with few and clear internal connections. The capacitors are assembled in a modular manner, which is easy to install and maintain, and more convenient for optimizing and adjusting the compensation capacity
04
remote terminal unit（RTU）
4.1
define
RTU (Remote Terminal Unit) is a remote measurement and control unit device responsible for monitoring and controlling on-site signals and industrial equipment. Compared with commonly used programmable logic controllers (PLCs), RTUs typically require excellent communication capabilities and larger storage capacity, suitable for more harsh temperature and humidity environments, and provide more computing functions. It is precisely because of the comprehensive functions of RTU that RTU products have been widely used in SCADA systems.
Remote Terminal Unit (RTU) is an electronic device installed at a remote site to monitor and measure sensors and equipment installed at the remote site. RTU converts the measured state or signal into a data format that can be sent over a communication medium. It will also convert data sent from the central computer into commands to achieve functional control of the device.
4.2
characteristic
(1) Long communication distance;
(2) Used in various harsh industrial environments;
(3) Modular structured design for easy expansion;
(4) Widely used in industries such as water conservancy, power dispatching, and municipal dispatching with remote signaling, telemetry, and control capabilities.
4.3
function
(1) Collect status data and send it to a remote location, with photoelectric isolation and priority transmission for remote signal displacement;
(2) Collect data volume and send it to a remote location with optoelectronic isolation;
(3) Directly collect the power frequency of the system, measure voltage, current, active and reactive power, and send them to a remote location to calculate the forward and reverse electrical energy;
(4) Collect pulse electrical measurements and send them to a remote location with optoelectronic isolation;
(5) Receive and execute remote control and return to school;
(6) Program self recovery;
(7) Equipment self diagnosis (fault diagnosis to plugin level);
(8) Equipment self adjustment;
(9) Channel monitoring;
(10) Receive and execute remote adjustment;
(11) Receive and execute timing commands (including optional GPS timing function);
(12) Communicate with two or more main stations;
(13) Collect event sequence records and send them to distant locations;
(14) Provide multiple digital interfaces and multiple analog interfaces;
(15) Remote/local settings can be made for each interface feature;
(16) Provide several communication protocols, each interface can transmit data of different protocols according to remote/local settings;
(17) Accept remote commands and select to send various types of information;
(18) Can forward remote control information from multiple sub stations;
(19) Local display function, local interface with isolator;
(20) Support communication with spread spectrum, microwave, satellite, carrier and other devices;
(21) Optional and multi protocol simultaneous operation, such as DL451-91 CDT protocol, should support POLLING protocol and other international standard protocols (such as DNP3.0, SC1801, 101 protocol);
(22) Remote settings can be made through telecommunications networks and power system channels.
Note: Taken from the Power Grid Think Tank. If you are dissatisfied, please contact us for deletion.
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