LOCATED on the western shore of Lake Macquarie, in the Lower Hunter Valley, New South Wales, Eraring Power Station is one of the largest power stations in Australia, comprising four 660 MW coal-fired units. These comprise IHI boilers, Toshiba turbo-alternators and Siemens analogue control systems.
Commissioned between 1981 and 1984, Eraring has a reputation in the industry for high plant availability, reliability and efficiency.
As part of Eraring’s plant upgrades, subsequent generating capacity will increase to 700 MW per unit.
To ensure continued reliability for the next few decades, Eraring Energy, the owner of the power plant, decided to replace the original hard-wired control equipment with a modern integrated control and monitoring system.
Significant project drivers were the requirements to maintain plant reliability and to gain operational improvements in order to ensure competitiveness in the deregulated Australian power market. The re-instrumentation work started in early 2003 under the leadership of Yokogawa Australia , which teamed up with TechComm Simulation, a wholly owned Yokogawa subsidiary.
The customer required an integrated system to control the operation of the boilers, turbines, generators and other balance of plant equipment. Yokogawa proposed an integrated solution comprised of a distributed control system (DCS), plant information management system, field device management system, full-replica training simulator and field instruments together with strong local support.
Plant reliability ensured
THE Eraring plant has four large units with a total system input/output (I/O) count of more than 40,000 as well as 25,000 interfaces to other plant auxiliary systems.
Yokogawa’s Centum CS 3000 R3 DCS supported this large application in a single architecture, while ensuring reliable plant operation with its “pair & spare” non-stop controller technology.
To satisfy the need for further operational improvement, a Yokogawa Exaquantum plant information management system was used for long-term data storage, data and alarm logging, and performance calculation.
The users can monitor the graphical data for both current and historical plant information in an Exaquantum window at their own PCs, using the Eraring wide area network. This makes it easier for operators and plant managers to keep informed and to make decisions for future plant operation.
The customer also desired to improve plant operation in the aspects of human resources and operating environment.
Yokogawa’s high fidelity, full-replica simulator enabled custom-made operator training that fully replicated the characteristics of the power station. This allowed the operators to be familiar with all aspects of plant operation, using the new control system before running the real plant.
The original analogue-based control room was replaced with a new control room.
ANOTHER important issue to be considered was system maintainability.
From the late 1990s (before the control system replacement), the customer had progressively upgraded its analogue field instruments, selecting Yokogawa DPharp EJA transmitters as well as other vendors’ devices.
A further requirement was to upgrade the original paper-based field device management system to a Windows-based, user-friendly tool which integrates various data from multi-vendor Hart and analogue devices into a single database.
The customer wanted system compatibility with the DCS and used the opportunity of the plant revamping to achieve tight integration of the field device management system into the DCS.
Yokogawa met these requirements for integrated device management across the Hart protocol with a combination of its Centum CS 3000 DCS and its Plant Resource Manager (PRM) software.
The new system integrates all field information into a single database on a PRM server and allows real-time, remote maintenance of many hundreds of devices, including around 500 EJA transmitters, via the DCS networks and Hart I/O modules.
The open architecture of PRM also allows the diagnostics of smart Fisher valve positioners via the Yokogawa DCS just by loading diagnostic plug-in software onto the PRM server. This integrated maintenance solution helped Eraring’s maintenance crew streamline plant maintenance work.
Minimum plant outage
ANOTHER challenge was the tight commissioning schedule. The first outage was planned 15 months after the initial order. To minimise the time taken for the control system replacement, Yokogawa proposed a solution making full use of the capabilities of the Yokogawa DCS and simulator.
The Centum has an engineering test function that enables an application functional test on a general-purpose PC without any real controller hardware.
TechComm Simulation developed the high-fidelity simulation system based on the detailed plant documentation supplied by the customer. Combining these capabilities, Yokogawa engineers were able to extensively test the new control system on the simulator prior to DCS commissioning, thereby minimising final tuning work, once the unit returned to service.
Eraring plant operators were well trained in the new control system, utilising the simulator. This avoided mistakes that could have occurred if they had not been familiar with the new system, ensuring a smooth plant commissioning process.
THE four units at Eraring were retrofitted progressively, with the first changeover in August 2004 and the second unit completed at the beginning of 2005.
The renovated units give very stable, and at the same time more flexible operation than before. After the revamping, the customer now makes everyday load changes at a rate faster than with the previous control system. This can provide financial benefits in the competitive Australian electricity market.
The 10 technicians/engineers at Eraring have to provide 24/7 responsibility for support and maintenance of all plant instrumentation and control systems including about a million field devices, thousands of control loops, chemical plant and environmental analyser systems, and existing analogue control systems, PLCs and unit computers.