Expansion of SCADA and energy management systems will improve the reliability and interface capabilities with the European network.
Turkey's first national load dispatch system was installed and commissioned in the 1980s. Supplied by a Westinghouse/Telettra consortium, the Wesdac32 system included supervisory control and data acquisition (SCADA) and an energy management system (EMS). The Turkish Electricity Transmission Co. (TEIAS) is owner and operator of the electricity transmission system in Turkey, as well as operator of the country's electricity market.
When first installed, the Wesdac32 SCADA/EMS system had one national control center (NCC) in Ankara, Turkey, five regional control centers (RCCs), and about 50 substations and power plants equipped with remote terminal units (RTUs). In addition to SCADA functions, the NCC also had some EMS functions, which were products of ESCA Corp. (AREVA SA). Later, the system was extended to include 75 substations equipped with RTUs.
In the early 2000s, the Wesdac32 SCADA/EMS system was replaced with the SINAUT Spectrum version 4.3 SCADA/EMS system from Siemens. This SCADA/EMS system is vitally important to ensure reliable operation of the Turkish power system. It provides the functionalities required to connect the Turkish power system to the Continental Europe Synchronous Area of ENTSO-E (European Network Transmission System Operators for Electricity). Therefore, TEIAS has assigned the highest priority to further expand the SCADA/EMS system.
At present, the TEIAS SCADA/EMS system covers all power plants and substations connected to the 400-kV transmission network as well as the important power plants and substations connected to the 154-kV subtransmission system. To be able to increase real-time observability and reliability of the Turkish power system, TEIAS intends to further expand the SCADA/EMS system to the remaining power plants and substations connected the 154-kV transmission system. A contract was awarded in 2008 for the installation of three new RCCs, and tender documents are currently being prepared for the extension of the SCADA system to the remaining 154-kV substations.
TEIAS's national load dispatch system has a hierarchical structure. The NCC is now located in Ankara. Six RCCs have been established in Adapazari, Samsun, Golbasi, Ikitelli, Izmir and Keban. In addition, TEIAS has an emergency NCC, which serves as the backup for the NCC. Each RCC is connected to the NCC through redundant communication links and to the emergency NCC through one communication link. RTUs at substations and power plants are connected to the related RCCs through redundant communication links.
A total of some 200 RTUs are now included in the SCADA system. By means of the SCADA/EMS system, the complete 400-kV transmission network as well as key substations and power plants on the 154-kV subtransmission network are monitored by the NCC and the related RCCs in real time.
All of the RCCs have SCADA functions. The NCC and the emergency NCC have EMS functions in addition to SCADA functions. The existing SCADA/EMS system was designed to be expanded to include up to 500 RTUs. Currently, TEIAS is continuing to extend its SCADA system to the remaining sections of the 154-kV subtransmission network.
The Hardware Configuration in the Control Centers
The NCC in Ankara has a distributed UNIX-based computer system consisting of redundant Sun Microsystems servers and workstations, which carry out the complex calculations involved in the operation and control of the electricity network. The emergency NCC has an identical computer system without redundancy. Additionally, the six RCCs are each equipped with their own distributed computer system from Sun Microsystems. A high-speed 100-Mbps local area network is installed in each control center, and a redundant array of independent disks (RAID) system is used for mass data storage at the national and emergency national control centers.
The redundancy configuration, hot-standby and spare server concepts are used at the NCC and RCCs. RTUs are connected to the related control centers by means of telecontrol interfaces at the RCCs. The NCC and RCCs have dynamic mimic boards, while the emergency NCC has a rear-projection system.
Accurate real time is maintained within the computers at the control centers by means of a GPS. Synchronization of the RTUs is maintained by the RCCs through time synchronization messages sent every 15 minutes through communication links.
Data communication between the national, emergency and regional control centers is realized through the router operating over TEIAS's own fiber-optic links, satellite links and leased lines from the Turk Telekom Co. The data communication speed between the RCCs and the national and emergency control centers is 64 kbps.
Data communication between the RCCs and RTUs occurs through power line carrier channels, TEIAS's own fiber-optic links and leased lines from the Turk Telekom Co. Speeds such as 200 kbps, 600 kbps, 1200 kbps, 2400 kbps, 9600 kbps and 19,200 kbps are used for data communication between the RTUs and RCCs.
To maintain system reliability, redundant communication links between the NCC and RCCs are used, and the communication links between the RCCs and RTUs are also redundant. The data communication protocol used between the control centers is in accordance with the IEC 60870-6 communication protocol (ICCP), while the IEC 60870-5-101 and F4F data communication protocols are used for the new and older types of RTUs, respectively.
Facilities also exist for the connections used for data exchange with other control centers such as the NCCs of neighboring countries in the future; the ICCP was installed for this purpose.
There is a need for the exchange of real-time and off-line data with the NCCs of neighboring transmission system operators as well as with the related coordination center in the UCTE network. This requires the integration of TEIAS to the electronic highway used for data exchange throughout the UCTE network. In addition to data communication, the communication system provides a private automatic-exchange telephone system throughout the network for voice communication between control centers, substations and power plants.
The SCADA system collects real-time data from RTUs located at about 200 power plants and substations, out of approximately 650 power plants and substations, connected to the Turkish national electricity network. Data collection includes analog measurements (active power, reactive power, voltage, frequency, transformer tap position and current), energy meter readings, switching equipment status data and alarm data. As a part of SCADA installation, the first stage of remote control is provided at 12 substations.
By means of the SCADA system, measurements are either telemetered every 10 seconds or transmitted spontaneously when changes in the measurements exceed the threshold values. Automatic generation control-related data such as the active power output of the generating units participating in secondary frequency control or tie-line active power flows are telemetered every two seconds. Accurate frequency measurement is monitored at the national and emergency control centers every second. In addition, backup is provided for the frequency measurement. Status and alarm data are telemetered by exception.
The process-controlling computer at each RCC regularly interrogates all the RTUs in its region through a telecontrol interface to update the database with current status and measurement data. The data from the updated database is processed and presented to the operators in the appropriate format. Data received from the RTUs is also transmitted to the national and emergency control centers as required. The data collected through the SCADA system is around 30,000 readings at present.
At the NCC, data received from the regions is used to generate the network display, reports and alarm lists, and it provides the basis for energy management computations. Set points computed at the NCC by the load frequency control program are transmitted through the RCCs to the power plants participating in the load-frequency control program.
The SCADA system has chronological event reporting facilities. Changes of state in the digital inputs from the RTUs are time-stamped with the occurrence time; the time-stamped data and change of status data are sent to the RCCs. New RTUs have 1-msec resolution for the time-stamping of status and alarm data compared with around 20 msec for the older RTUs.
The system has comprehensive data archiving and trending capabilities as well as a disturbance data collection facility at all the control centers. The national and emergency control centers have a relational database, the Oracle database from Oracle Corp. The capability to transfer data from the historical and future databases to the Oracle database is available at the national and emergency control centers.
A UNIX-based Solaris operating system from Sun Microsystems is used for servers and workstations in the SCADA/EMS system, and the PCs connected to the SCADA/EMS system use Microsoft Windows NT version 4.0. The TEIAS SCADA/EMS system is a multi-site system from the database management system point of view. This feature of the system provides the capability to automatically transfer all database and display additions and modifications carried out at the NCC to all control centers through ICCP communication links.
Energy Management System Functions
In addition to SCADA functions, the following EMS functions are available at the national and emergency national control centers:
- State estimator
- Contingency analysis
- Dispatcher load flow
- Load-frequency control/automatic generation control
- Economic dispatch
- Reserve monitoring
- Interchange transaction scheduler
- Hydro thermal coordination
- Short-term load forecast
- Dispatcher training simulator (at the NCC only).
Expansion of the Existing System
Currently, TEIAS is continuing to expand the SCADA/EMS system to the remaining part of its 154-kV subtransmission network. In accordance with the requirement of the system connection agreements signed for connection of the power plants and substations to TEIAS transmission network, all power plants and substations connected to the 400-kV transmission and 154-kV subtransmission networks should be included in the TEIAS SCADA system. To fulfill this objective, the power plants and substations to be connected to the TEIAS transmission and subtransmission networks must have the necessary equipment, RTUs or distributed control system installed and connected to the TEIAS SCADA system.
A new contract, with a value of some 5 million euro (US$6.79 million), was awarded in July 2008 to Siemens AG for the supply, installation and connection of three additional RCCs (located at Seyhan, Erzurum and Kepez) to the existing SCADA system. Also included in the scope of this 24-month contract, an additional 75 RTUs will be connected to the SCADA system.
TEIAS also plans to install around 150 more RTUs in the existing substations connected to the 154-kV subtransmission network within the areas of the existing six RCCs. Currently, TEIAS is preparing the tendering documents for the supply and installation of these additional RTUs to be used for the expansion of Turkey's national load dispatch system.
Turkish Power System Statistics (2008)
- Total installed generation capacity: 41,802 MW
- System maximum demand: 30,517 MW
- Annual increase in demand: 4.2% (less than the recent 8% average)
- Annual generation: 198 TWh
- Transmission system voltages: 400 kV, 220 kV, 154 kV and 66 kV
- Total length of the transmission lines: 46,536 km (28,916 miles)
- Total transmission transformer capacity: 85,277 MVA
- Number of transmission substations: 539
Bahadir Ucan ( firstname.lastname@example.org) was awarded bachelor's and master's degrees in electrical and electronics engineering by the Middle East Technical University in Turkey in 1982 and 1985, respectively. Later, he earned an MBA degree from Ankara University, having completed his MBA thesis in the field of restructuring the electricity industry. Ucan has spent more than 25 years with the Turkish Electricity Transmission Co. (TEIAS) and its predecessor companies (TEK and TEAS) as a power system engineer specializing in SCADA and EMS systems. He is a member of the Chamber of Electrical Engineers in Turkey, and has participated in many working groups and committees in TEIAS and worked on various international projects.
Sidebar: Companies mentioned in this article:
Turkish Electricity Transmission Co. www.teias.gov.tr
AREVA SA www.areva.com
Oracle Corp. www.oracle.com
Sun Microsystems www.sun.com