Kazakhstan’s Electricity Grid Operating Company (KEGOC) has engaged Siemens PTD to undertake a major modernization of the country’s transmission and distribution network. The project is aimed at increasing system reliability and will provide better protection against blackouts.
Semion Rabinovich, Siemens Power Transmission and Distribution, Kazakhstan
As part of the modernization of its power supply network, Kazakhstan, the ninth biggest country in the world in terms of area, is planning to increase the reliability of power transmission and the availability of electrical systems in its network. The country has placed large-scale orders with companies from the power transmission and distribution sector, one of which went to Siemens Power Transmission and Distribution (PTD).
Figure 1. The 220 kV Chimkentskaya substation in Kazakhstan, halfway between Astana and the Aral Sea, will be the first of 67 substations in the country to be equipped with modern control and protection devices
The customer is the state-owned Kazakhstan Electricity Grid Operating Company (KEGOC), which operates the extra high voltage and high voltage network from 110 kV to 1150 kV along with the associated switchgear and substations. KEGOC, located in Astana, owns 338 000 km of transmission lines at these voltage levels, the transformer substations and the country’s main load dispatching centre. Besides managing the grid in the liberalized Kazakh energy market, KEGOC also trades energy with neighbouring countries.
One of the tasks entrusted to Siemens by KEGOC was the equipping of all the country’s 67 substations with the latest digital substation control and protection, worth a total of g50 million ($63 million). An extra g34 million was the cost of 504 high voltage circuit breakers to be delivered over a period of three years. The order also included the delivery of 600 surge arresters (100 kV, 220 kV, 500 kV). Furthermore the order covered the delivery and installation of a national network control centre and nine regional control centres connected with the main control centre ” costing a total of g14 million. The delivery of 250 powerline carrier systems rounded off a deal worth g100 million to Siemens. The project is currently underway with the last delivery of powerline carrier systems due in 2006 and the last digital control and protection system is set to be in operation in 2009.
Siemens PTD equipped Kazakhstan’s 67 substations (for high and extra high voltage) with digital control and protection systems. The aim was to improve the reliability of power transmission as well as the availability of the network’s electrical systems. In addition to the supply of hardware and software for power automation, the scope of performance also included engineering, commissioning and training of maintenance and operating staff.
All analogue electronic protection devices in the transformer substations were replaced with Siprotec digital systems. The panels in the substation control rooms were replaced by modern display workstations for the staff. A control system was used based on Sicam and Siprotec components, offering a uniform solution for the control and monitoring of power transmission and distribution.
Figure 2. Substation control and protection for the Kazakhstan project: a system was used that offers a uniform solution for the control and monitoring of power transmission and distribution
The main reasons for the Kazakh grid operators choosing Siemens substation control and protection were the easy handling of system components, their resistance to interference, long service life and facilities for providing operating and diagnostic data.
Low temperature reliability
As well as the substation control and protection for Kazakhstan’s modernization project, Siemens also delivered a total of 504 high voltage circuit breakers of both the dead-tank and live-tank variety for voltage levels between 123 kV and 550 kV. Installation and commissioning of the last 78 circuit breakers are scheduled for completion in September 2005.
Kazakhstan’s climate with its cold winters and hot summers represents a special challenge for the circuit breakers. Temperatures of -55à‚°C in the north of the country provide a real test for the equipment. Starting in the bid phase, Siemens experts developed special solutions to adapt the circuit breakers to such extreme temperatures so that they may function whatever the Kazakhstan climate has in store for them. In the south, for example, dead-tank circuit-breakers from the 3AT2DT range for 550 kV are being used. They are equipped with heating elements that allow them to operate at ambient temperatures of -55à‚°C. To combat these low temperatures, Siemens equipped these circuit breakers with solid insulators and, for the first time, with a specially developed thermal jacket. At the operator’s request, a 3AP1 dead-tank circuit breaker with one mechanism per pole was supplied for the 245 kV voltage level. The advantage here is that in the event of a short circuit, single-pole autoreclosure is possible. Should a short circuit occur, only the affected phase is disconnected and power continues to be transmitted in the other phases.
Total network control
Following the delivery and installation of the national network control centre, a back-up centre with equal functionality as well as nine regional control centres linked to the main control centre in multi-site operation, KEGOC looked to Siemens Group when it came to power systems control. The country’s 11 control centres are spread over a wide area but the multi-site function allows this Kazakh power utility to maintain data centrally. For KEGOC this not only makes data management much easier but also reduces operating costs.
The control centres work with modern SCADA/EMS functions from the Sinaut Spectrum product portfolio. These cover network analysis, network optimization, load frequency control, load forecast and functions for the liberalized energy market such as bottleneck management (including monitoring of the power plant generation schedule and relevant data exchange interfaces between the network operator and the energy exchange).
Figure 3. Siemens developed a special solution for this 550 kV dead-tank high voltage circuit breaker, enabling it to function trouble-free even when ambient temperatures in Kazakhstan fall to -55à‚°C
Particular attention was paid to the special requirements arising from the transmission network’s vast geographic expanse. Corona losses and regulations regarding the maximum transmission capacity of power lines also had to be considered. A training system was included in the package so that KEGOC can familiarize all its staff with the functions of the new SCADA/EMS system. The training system is similar to a flight simulator and replicates all the functions and dynamics of real-time operation.
To ensure optimal operating conditions, all the network control centres work with large-display projection systems, on which all graphics and reports from the SCADA/EMS system can be displayed with multi-window technology, providing all the staff in the control room with a quick overview of the current network status. Installation and commissioning of the SCADA/EMS system are scheduled for completion in 2006/2007.
The Sinaut Spectrum network control systems represent an important investment for KEGOC, aimed at ensuring security of supply in the Kazakh energy transmission network. These systems give the power provider total observability of the network in the control centres, an important prerequisite for secure and optimal network management and ensuring that any faults that occur can also be quickly rectified.
High voltage communication
In order to operate (from the network control centres) the high voltage switching devices and the substation control and protection equipment spread across the entire country, communication facilities are required that cover the thousands of kilometres making up the Kazakhstan grid. To handle this task, Siemens supplied over 250 power line carrier (PLC) systems. “What makes PLC systems so special is that the high voltage lines are used as communication channels. They can serve for telephoning, transporting data (required for grid control) and especially for transmitting the anti-breakdown commands so typical for the CIS region; these commands contribute to efficient protection of the power network and help to prevent blackouts”, comments Siemens PLC expert Marc Jablonowski.
In Kazakhstan, as in other parts of the CIS, the protection signal transmission functions for the electricity grid is performed in a way particular to the region: a much greater number of protection commands than is usual can be transmitted with the aid of the power line carrier technology. The PLC systems are equipped with extra intelligence and perform tasks which elsewhere are handled by network control centres (anti-breakdown automation). The job of safeguarding against blackouts is decentralized to a huge extent.
To make sure that Kazakhstan is better equipped to meet the demands of free electricity trading in the liberalized market, Siemens PTD is supplying the operator of the Kazakh electricity spot market with a system for such energy dealing.