Using the Internet to improve power plant performance remotely

The Internet is having a profound effect on the world of process control, with its ability to support a set of standard components for communication between software applications. Its rise is helped by improvements in communication links (Gigabit Ethernet, ATM, etc), by the low costs of implementation, by new software technologies (Active-X, applets and servlets, Java, etc) and by the adoption of standard communication protocols (such as FTP, TCP, and HTTP).

In power plant technology one marked effect is to encourage an integrated approach to site management.

The integration of Internet technology into the Alstom power plant control system, the Alspa P320, has opened the door to new applications such as:

• Remote diagnostics and maintenance.

• Remote monitoring and control.

• Multi-site remote assistance services (maintenance support drawing on remote experts).

The Alspa P320 system, which is applicable to all types of power plant, including fossil, hydro and nuclear, integrates distributed control system (DCS) and plant management functions. The Alspa P320 has been fitted with an on-site web data server that gives access to all the control system data, providing the operator with the possibility of pre-selecting the measurements and event recordings needed for remote analysis. It can be used to provide Internet access to plant-wide data for an operating unit. Among the plants currently making use of this capability are Sual in the Philippines (2x600 MWe), Lavrion in Greece (1x550 MWe), Luo Huang in China (2x360 MWe), several EDF fossil plants in France, and Foz do Areia in Brazil (4x450 MWe).

The Alspa P320 system is composed of a set of automation cells called Controbloc. Each automation cell is structured around the deterministic F8000 field network. Based on WorldFip technology, it integrates all the equipment to control the process, including multi-function cell controllers, field controllers, field intelligent devices and gateways.

Controcad, a powerful engineering workshop, manages the complete P320 system.

The Alspa P320 distributed control system is organised on an open fieldbus-based architecture. This open architecture requires highly reliable communications resources. Distributed equipment is linked by standard networks – an Ethernet IEEE bus between workstations and the Centralog control room data server, an S8000 bus for PLCs and an F8000 WorldFip fieldbus between PLCs and the process field controllers they serve.

Centralog integrates the power plant control and supervision functions and is also the host for expert software packages (supplied by Alstom or others), and supports the site management facilities. It is the Centralog that integrates the Web function at the operator station level. This function permits access to operational data, either locally through the Intranet or remotely through the Internet. Operational data stored in the Centralog database are available at the operator stations and are also accessible through a browser such as Internet Explorer or Netscape. On an operator connection the Web server installed in each on-site P320 system loads a Java applet to the browser (without pre-installed software or driver) and on an operator request operational data are exchanged and can be used for expert analysis or maintenance support.

The welcome page of the Centralog Web function permits access to operational data. This access is of course protected by password and a firewall (if necessary). Two types of operational data are accessible to a remote operator: the events list and measurements of key power plant variables. These data are archived each day, with the operator able to access the current data or previous days’ data. The data can also come from an archive library. Filters can be employed to select the information that the user wishes to consult.

In a side newspaper, events are colour coded according to their significance.

The case of Sual

Alstom has been the lead contractor for the design and commissioning of the power generation and control systems for the 1218 MWe Sual coal-fired plant in the Philippines. The Alstom scope included boiler, turbo-generators and plant engineering, as well as the Alspa P320 system.

In Sual the S8000 bus linking the PLCs included 7 km of wiring. The Sual power plant includes 36 automation cells, each one with a fieldbus, up to ten communication links to miscellaneous equipment from other suppliers managing up to 25000 I/Os. Networks and equipment are all backed up to guarantee the system’s security and availability and ensure immediate data saving. All the advanced functions required by operators are integrated in the system, optimising operation and maintenance. All equipment – including the Alspa P320 digital control system – had to be checked, tested and certified before being delivered within the space of only four to six months. To meet these deadlines, Alstom used a Controtest simulator which had been implemented prior to plant commissioning. This enabled modeling of I/Os without having to wire them up, evaluation procedures, and configuration of the software specifically developed for the Sual plant.

Alstom has also provided a training simulator to create a virtual control room, which promises significant savings in the operation and maintenance of the plant. It offers trainee operators the same control and supervision conditions and resources as those in the actual control room. The simulator comprises a Centralog control and supervision system and a powerful computer for dynamic real-time simulation of the process for both the PLCs and controls, as well as exchanges with trainee and instructor stations. Use of the simulator will not be confined to the training of novices or providing refresher training for experienced operators. It will also be used to analyse trips and evaluate new control strategies during the lifetime of the plant.

The special situation of the Sual plant, the need to provide the customer with support for commissioning, first industrial operation and analysis of the process led to two major requirements:

• all data to be gathered within the same system to facilitate remote access to plant data;

• secure access to be provided to these data from any PC in the Alstom group and its partners.

To meet these requirements, it was decided to provide Internet-based access to plant historical data stored in the control system.

So far, the adoption of this architecture has produced some very positive feedback, with operators deriving some very substantial benefits from it. For example:

• From the start of commissioning tests, access has been provided to the preliminary measurement records taken on the system, enabling the Alstom team to reset certain values as necessary.

• Commissioning and setting of controllers could be followed by the designers in real time.

• Co-ordinated tests on the boiler–turbine could be simultaneously accessed by the partners involved in the process without time delay, loss of information or loss of quality of information.

• Commissioning, operation and response times to operator requirements have been improved thanks to the possibility of immediate access to diagnostics from experts in various R&D, manufacturing and engineering centres around Alstom.

Future developments

Based on the positive feedback to date, both technical and economic, the Internet connection has been implemented on all recent Alstom power plants.

Further developments are underway on the Alspa P320 to enhance the system by:

• improving the human–machine interface by using Java;

• allowing WIN NT access to bulk test records, which can be transferred over the Internet and re-input in CAD tools;

• using the Internet to provide remote image viewing for following-up of tests directly at Alstom lead centres;

• building on the site Internet server to provide a complete future portal to assist operations with support from Alstom lead centres, enabling operators to improve predictive maintenance of their plant.