Ulaanbaatar gets a power lifeline

Yokogawa's Netherlands office has received an order to supply turbine control systems for Mongolia's largest thermal power plant (full name Ulaanbaatar Thermal Power Plant No.4, State Owned Stock Company) which is located in the country's capital Ulaanbaatar.

The need for an extensive upgrade is pressing. In recent years, Mongolia has achieved a remarkable rate of economic growth, driven by the development of mineral resources, reaching 12.3% in 2012. Accompanying this growth, the population has risen rapidly in recent years in Ulaanbaatar, the centre of Mongolia's government and economic activity, reaching about 1.3 million in 2012 (more than 40% of the country's population) and the city has also seen a concentration of manufacturing facilities emerge.

It is expected that the power demand on the central power system, which covers Ulaanbaatar, will increase annually between 6 and 7%. Ulaanbaatar plant No.4 is one of the country's primary power plants, providing about 65% of its total grid capacity, but aging of the turbines, the boilers and some of the other equipment has led to instability in the power supply with a drop in power generation efficiency and more unplanned outages. Improving efficiency and stabilising the supply by restoring the plant's functions is therefore an urgent issue for Mongolia's power sector.

The ¥2.1 billion project is being undertaken to improve, primarily, the efficiency and stability of the facility's operations. The eight-unit plant has a total capacity of 703 MW but also supplies 1373 Gcal/h (12 000 t/h) of hot water for the district heating system in Ulaanbaatar, meeting about 65% of the city's heating demand. Temperatures in this region fall as low as -40oC in mid- winter, so this power plant is a crucial lifeline for the city's residents.

The project is financed by a loan from the Japan International Co-operation Agency (JICA). Ulaanbaatar No.4 has received long- term support from Japan, including grant aid and loan assistance since 1992.

Refurbishment

For six of the plant's turbines, obsolete mechanical speed governors will be converted to electronic governors, and control systems and instrumentation will be replaced. In addition to supplying the CENTUM VP integrated production control system for the control and monitoring of the turbine governors, and auxiliary facilities such as the feed water pump control system, Yokogawa will provide field devices such as DPharp EJA series differential pressure/ pressure transmitters, liquid analysers, control valves, and safety valves.

Yokogawa will also have full responsibility for the implementation of this renovation project, starting with the survey of existing facilities and proceeding through to the detailed design, delivery, and installation of instruments, related erection work, commissioning, and staff training. The work will proceed in stages. The first of the renovated turbines is scheduled to be returned to service in June 2017.

Previous upgrades

Yokogawa received orders during 1997 and 2003 to provide control systems as part of a project to renovate the boilers and related instrumentation at this power plant. Consequently, all of these facilities are now monitored and controlled by Yokogawa Centum series control systems. As the result of these upgrades, the power station was able to reduce its coal consumption by more than 20% during the 1997 to 2007 period.

Distributed control system

Centum VP is the latest version of Yokogawa's integrated production control/ distributed control system family. It is said to have a more intuitive human machine interface, and power field control stations capable of processing data faster and more reliably. It is claimed to achieve 99.99999% availability, owing to features such as a 'pair & spare' CPU configuration. It also provides system operators access to intelligent diagnostics and subsystem data.

Its architecture is standard, consisting of human machine interfaces, field control stations, and a control network configured in four main sections - operation and monitoring, engineering, control functions, and a network communication system.

The unified gateway station (UGS) acts as an interface, allowing Centum VP to communicate with STARDOM network-based control systems or other third-party subsystems such as Modbus RTUs, Modbus/ TCP units, EtherNet/IP units, OPC DA units, and intelligent electronic devices (IEDs). It utilises the widely adopted EC 61850 protocol.

Coal handling refurbishment

The I&C works run alongside a project contracted to Mitsubishi Hitachi Power Systems to refurbish eight units at No.4 plant. MHPS will implement the refurbishment work, slated for completion in October 2018, in co-operation with MCS International LLC, Mongolia's largest engineering company.

The refurbishment, including the addition and/or renewal of related equipment, will be performed on the core components of the coal pulverisers in units 5 to 8. These will be renewed to extend their service life, while soot blowers will be added to all units from 1 to 8 to prevent fall-off in heat-exchange efficiency. When completed, the refurbishment is expected to contribute to the realisation of a significantly more stable power supply.