Control + Intrumentation: Technological revolution

Mr.Te-Chang Chan,Westinghouse Process Control Inc, USA
Mr. Zhao Zu-Cheng,Ping Liang Power Company Ltd, China

In early 1999, the Gansu Electric Power I0ndustry Bureau selected Westinghouse Process Control, Inc. (WPC) to supply a digital control system (DCS) for units one and two of the Ping Liang power plant. This selection reflected their ambition to invest in a powerful process controller, but using a technology that had not been tested in China was a concern to the owners, Beijing Electric Power Technology Corporation (BEPTC) and Northwest Electric Power Design Institute (NWEPDI).

In order to minimize this concern a detailed DCS implementation plan was developed with special focus on technology transfer. A special training session was conducted for BEPTC and the commissioning engineers to enable them to take full advantage of the new system. Technical support by Westinghouse engineers at BEPTC and the Ping Liang site in China was also a key factor to the success of the project. Conducting a full scope of customer factory acceptance tests at BEPTC proved to be imperative in demonstrating the accuracy and reliability of the DCS system and, hence improved the confidence of the owners.

In a competitive power market environment, it is difficult for a plant owner to select a DCS supplier that is capable of delivering reliable and advanced control technology to meet the plant-specific needs. In addition, this DCS control system must allow rapidly advancing microprocessor technology to be easily integrated into the system.

After a thorough technical evaluation on various DCS suppliers, WPC was selected by the owners as the DCS supplier to provide the Ovation system for the Ping Liang power plant.

Selection

There are two fossil fuel power plants in China’s Gansu province utilizing WDPF for plant control and monitoring applications. With the successful operation of both power plants and a large number of operators and engineers already exposed to this technology, it is logical for the owner to take full advantage of these experienced engineers to construct and build new power plants. These experienced engineers include various disciplines ranging from plant I&C engineers to control room operators.

In order to avoid DCS hardware and software becoming obsolete in the future and to minimize the dependence on the DCS supplier, an open architecture design of the DCS system using a PC-based Pentium microprocessor was very attractive to the owner. The introduction of WPC Ovation to the China market in late 1998 was just in time to meet the owner’s desire for advanced control technology.

Though WPC receives a remarkable grade on the merit of Ovation technology by the owner’s technical review board, the evidence of assurance on the reliability and safety of the plant operation still needed to be addressed during the selection process. An Ovation site visit by the owner and the end user alleviated any concern. A comprehensive Ovation implementation plan became essential and was developed to provide further assurance to the owner.

“We selected WPC as the supplier of the DCS system because of their overwhelming command of the power marketplace, reputation, and the superior grade of their Ovation technology,” said a member of the review board after the selection of Ovation for the Ping Liang power plant.

The Ovation system provides integrated modulating control, sequential control, and data acquisition to provide a reliable and advanced DCS. Each Ovation Controller is microprocessor-based and is capable of processing data using a multi-tasking, commercially available, real-time operating system (RTOS). The main elements of the Ovation system are Ovation Controllers and the workstation platform.

The Ovation Controller is based on standard industrial Pentium processor architecture. It incorporates RTOS that provides full multi-tasking with preemptive task scheduling. By utilizing Intel’s widely accepted 32-bit PCI expansion bus, the Ovation Controller provides a fully open PC platform.

The Ovation Controller executes simple or complex modulating and sequential control strategies, performs data acquisition functions, and interfaces to the Ovation FDDI network and I/O subsystem. Having a standard PC architecture and passive PCI/ISA bus interface, the controller is compatible with other standard PC products.

The hardware platform and operating systems for the Ovation Controller offer the following features:

  • Reduced risk of hardware and software obsolescence
  • Minimal cost and complexity of hardware and software upgrades
  • Increased ability to track advantages in technology.

Power and flexibility

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The Ovation Engineer/Power Tools workstation provides the stability, power and flexibility needed to operate modern process control systems. The UNIX-based Ovation workstation is fully compatible with the Ovation FDDI Network with access up to 200 000 points. Ovation Power Tools is a fully integrated set of advanced software programmes used for creating and maintaining Ovation control strategies, process graphics, point records, report generations, and system-wide configurations. Power Tools interacts with Ovation’s Relational Database Management system (RDMS) to coordinate and maintain a secure master compilation of all configurations. Ovation Power Tools also includes the following applications: Controller Builder, Graphics Builder, Point Builder, Configuration Builder, Security Builder and I/O Builder.

Controller Builder: The Control Builder is a AutoCAD-based software package that speeds up the creation of Ovation control strategies, and generates an executable code which can be downloaded on to the controllers. The Control Builder free-forms drawings consisting of control symbols, signal names, and signal connections. It creates all internal and default points associated with control algorithms, which supports the creation of new points required during drawing generation. It provides a wide-view, free-format environment for a “one screen” overview of control configurations.

Graphics Builder: The Graphics Builder allows the user to create and edit full-colour displays with resolution up to 16 000 pixels. Using a scrolling menu the user can adapt objects to meet their needs.

Point Builder: The Point Builder enables users to add, delete, or modify process points objects. It verifies that the points being deleted are not required for other areas, and notifies the user of any conflicts. Users can define I/O parameters – I/O type, card type, hardware address, termination information, sensor type, calibration, and conversion coefficients – and queries the database regarding any data point.

When adding points the Point Builder checks for the duplication of names throughout the system and whether attributed values for point fields are the correct type and range.

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Configuration Builder: The Configuration Builder defines and maintains the data associated with all Ovation system device configurations. The user may define type and software compliment, parameter definitions for workstation software packages, and hardware definition. In addition to defining drops and maintaining data, the Configuration Builder is able to configure the controller and maintain the security system. The Configuration Builder delivers an installation mechanism for each component of the Power Tools. This incorporates a set of default configuration values and a set of derived values based on the system configuration. This means that upon installation users can run the configuration without any further interaction.

Security Builder: The Security Builder allows the user to create or delete security selections for system functions and point data. Security selections are saved in the Power Tools database and are distributed throughout the system. Local and remote security are provided. This system allows for definition of various levels of access to the system, based on user name, drop function, or point by point access.

I/O Builder: The I/O Builder is a hierarchical format for creating Ovation I/O module branches. It displays the system network, units and drops. The user selects the appropriate drop, defines the appropriate I/O branch type, the slot in which the I/O card will reside, and the type of card desired.

Ovation takes advantage of FDDI technology – the fastest, highest capacity communications network available for mission critical process control applications. Ovation FDDI Network is media dependent, allowing both fibre optic and/or copper (CDDI) implementation. By utilizing widely available commercial hardware, the Ovation Network obsoletes the complex bridged architecture of conventional DCS systems, eliminates the need for customer gateways and interfaces, and provides full connectivity with corporate LANs and Intranets. The high speed, high-capacity Ovation FDDI Network has the advantage of: speed of 100 megabytes per second, capacity of up to 200 000 real-time points per second, length of up to 200 km, and up to 1000 nodes.

Redundancy

The Ovation Controller is designed to accommodate multiple levels of redundancy for key components, including:

  • FDDI network interface
  • functional processor, memory, and network controller
  • processor power supply
  • I/O interfaces
  • input power feed
  • I/O power supply
  • auxiliary power supply
  • remote I/O communications media.

The Ping Liang project utilized eight Ovation Controllers and seven workstations per unit. Ovation Controllers, Ovation Network, and Ovation system software were supplied by WPC while the UNIX based workstations were purchased locally by BEPTC to minimize the project cost and increase the competitive edge.

The compact modular I/O design reduces the size of the Ovation cabinet and eliminates the requirements of the termination cabinet. As such, the electronic room used to house controllers can be downsized.


Technical support

BEPTC’s scope of supply includes DCS application software development, implementation, and commissioning. In addition, local procurement, including Workstations and printers, are also included. Although BEPTC has extensive experience on WDPF technology, the Ping Liang Ovation system still represents a challenge to BEPTC engineers due to the difference in software implementation technique, and hardware design philosophy between WDPF and Ovation.

Recognizing that improper use of Ovation Power Tools to implement application software is dangerous and costly, an early start on Ovation training for BEPTC engineers was essential. Comprehensive three-week Ovation training at WPC was therefore conducted to enable the engineers to become familiar with Ovation architecture and Ovation Power Tools. With their working knowledge of WDPF systems, all the BEPTC engineers easily grasped the skills needed and can effectively utilize all of the Ovation Power Tools.

Considering this is the first Ovation installation in China and BEPTC had no previous knowledge of how to install and configure an Ovation Software Server, one of the workstations purchased locally by BEPTC in China was shipped to WPC in Pittsburgh, USA, for Ovation system configuration and software installation. With this approach, a few unnecessary system software loading problems were avoided and it also expedited the overall application software implementation process.

The Ovation technical knowledge transfer was not limited to the classroom training; an experienced Ovation instructor was assigned to provide technical assistance for two weeks after the system was staged at the BEPTC facility in Beijing. Various technical questions raised during software implementation were resolved quickly.

In parallel, Ovation training was also conducted at WPC for plant commissioning engineers and control room operators for five weeks. This training concentrated on software and hardware maintenance so that plant engineers could perform the required regular maintenance.

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Prior to the shipment of the Ovation system to the Ping Liang site, a full scope of customer factory acceptance test was conducted at the BEPTC facility to demonstrate the capability of the plant operation using the Ovation system. The customer acceptance test teams consisted of members from the owner, end user and and Gansu Electric Power Test and Research Institute. A detailed point-by-point I/O test was performed to ensure the I/O point assignment cable wiring was correct. A simplified boiler simulator model downloaded in a controller was working in conjunction with other DCS control system controllers to simulate real plant operation. The successful simulation of the plant operation demonstrated the reliability and accuracy of the system and therefore increased the confidence of the owner. The customer factory acceptance test lasted more that two weeks.

WPC was aware that commissioning DCS at the site is the most critical time in determining whether a project is going to be successful or not. An experienced WPC Ovation engineer was therefore dispatched to the Ping Liang site for a six week assignment to provide Ovation technical support and commissioning activities. This proved to be critical because it resolved several unveiled problems that are not easily detected at the factory. In order to take advantage of the presence of the WPC Ovation engineer, a few Ovation training sessions were conducted by the WPC engineer to further improve site engineer’s Ovation knowledge.

WPC strongly believes that training is a key element of a successful DCS project and that it should be considered as an integral part of project execution. A DCS project cannot be considered a success if the end user is not capable of operating and maintaining the DCS system.

The Ping Liang unit one Ovation system was delivered to the site in November 1999 and was successfully installed at the site in January 2000. The DCS commissioning was initiated by BEPTC engineers starting April 2000, and a WPC Ovation engineer was at the site from late May until early July 2000. The progress made on the Ovation Control system is extremely advanced and the owner is pleased with the results. The plant performed a 168-hour test run at the end of September and commercial operation begin in October 2000.

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