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Power Plant Operation: Southern Comfort

Saudi Elecric Company needed more robust and efficient operation of its power plants in the south of the country and decided that a new distributed control system was the solution.

David Coslin, GE Energy, USA

Midway through 2004, GE Energy was awarded a contract to supply distributed control systems (DCS) to the Saudi Electric Company (SEC). The SEC is the state-owned utility that was formed to consolidate ten regional power companies within Saudi Arabia and which now produces around 84 per cent of the Kingdom’s electricity.

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In association with the National Construction Company (NCC) and Al-Toukhi Company for Industry and Trading (TIT), GE will help SEC expand their existing power generating capacity in the southern region of Saudi Arabia. One of the fastest growing areas in the country, the southern region has experienced a six per cent annual increase in electricity demand over recent years, compared to 4.5 per cent across the country, requiring additional investment in infrastructure in order to sustain the growth.

Consolidation needs

The contract scope consisted of power plant expansions at three simple cycle power plants located in Asir, Bisha, and Jizan. Asir and Bisha, located around 800 km south of Riyadh, run both GE 7EA and Siemens V84.2 gas turbines. The Jizan plant is in a remote southwestern location and runs GE 7EA gas turbines.

The plants currently utilize only minimal plant automation processes and systems, requiring a significant investment in operation and maintenance staff to keep them online and operating safely. In an effort to reduce operating costs, SEC needed to consolidate operation and maintenance activities for these sites in a central control facility in Abha, which is near the Yemeni border.

SEC identified several criteria that needed to be met in order to successfully combine its operations in Abha. Firstly it needed to implement standard process monitoring and control systems across its southern region fleet. By incorporating common systems at its sites, SEC would be able to automate routine tasks, enabling technicians to focus on more complex activities. Additionally, using robust systems with common communication protocols would also facilitate remote monitoring, a key requirement.

SEC also required that the solution provider utilize common hardware, spares, and tools for the DCS and turbine controls across the fleet of gas turbines from a variety of OEMs. In addition to simplifying training needs, a common platform would provide for lower inventory levels for spares and maximize the use of tools and core engineering assets for maintenance and repair across control systems. SEC operators would only need to learn one set of hardware, software, and maintenance procedures, thereby reducing training costs and improving transferability of skills.

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Figure 1. The DCS uses common hardware architecture and shared plant and unit data highways

Chosen solution

GE Energy and SEC collaborated to develop the controls solution that would enable SEC to streamline its operations and address its needs. GE’s solution was based on leveraging the flexibility of its Mark VIe turbine control system to create an integrated plant environment. By replacing the existing GE controls on the GE turbine at Asir with Mark VI controllers, GE plans to deliver a turbine control with the latest in monitoring and performance analysis capabilities.

The Mark VIe DCS solution will also integrate the turbine controls on the BBC turbines at Bisha with the plant-wide control system, as well as link the new Siemens V84.2 turbine controls (Teleperm XP) at both Asir and Bisha. At the Jizan site, the Mark VI turbine controls on the GE 7EA will be seamlessly connected with the Mark VIe DCS offering.

This custom-designed solution is built on proven hardware platforms that will help maximize the availability of SEC’s turbines. GE Energy’s Mark VIe DCS will contribute to minimized installation costs through the use of common hardware architecture and shared plant and unit data highways. Additionally, SEC will be able to make the most of plant and turbine operating data with GE Energy’s proprietary software application, ToolboxST, which enables operators to configure and programme all software functions from one, central facility. ToolboxST delivers detailed supervisory data from each of the plants ” down to the I/O level ” with robust monitoring and diagnostics software applications, alarms, and dual historians with resolution of less than 1ms.

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In announcing the order in September 2004, Ricardo Artigas, president, energy services, GE Energy said: “The Mark VIe was developed from customer requests to provide a control system that could meet the advanced performance requirements of modern power plants, with the flexibility needed for an ever-changing fleet.”

Mark VI

GE originally designed the MarkVI for the Advanced H-Class gas turbines but its modular and scaleable design means that it can also operate with even the smallest turbines. It is available in simplex or triple modular redundant (TMR) configuration. The equipment has easy-to-use operator interfaces and is designed to change out easily without the need to remove the terminations.

When the GE Energy solution is completed later this year, the integrated plant approach will result in a simplified control solution that helps optimize reliability while minimizing installation and hardware costs. By utilizing shared data highways and fewer engineered interfaces than traditional plant-wide control systems, the Mark VIe DCS is expected to enable NCC to reduce its total plant installation expense by 25 per cent. The simplified structure will also enable TIT to more efficiently tune and troubleshoot the hardware once installed.

Strengthened infrastructure

GE Energy’s Mark VIe DCS solution is projected to completely meet SEC’s criteria and enable the energy provider to consolidate southern region operations in a centralized location. In implementing a common operator interface and tools, greater efficiency and improved plant co-ordination will be possible using fewer operators. The acquisition of plant data and the evaluation of operating performance will be simplified and there is expected to be a saving in terms of spare parts and training costs.

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Figure 2. The equipment is designed to change out easily without the need to remove the terminations

The retrofit project has now began with the units having been shipped recently. Installation is scheduled for the Fall 2005. The improved process efficiency and enhanced control system effectiveness at Azir, Bisha, and Jizan will contribute to a strengthening of the infrastructure in southern Saudi Arabia, an outcome that is critical for the vitality and growth of the region. MEE

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“SEC… needed to implement standard process monitoring and controls systems across its southern region fleet…by incorporating common systems at its sites”

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