Modernisation of Landsvirkjun’s speed governors prompted an investigation into Y2K issues
Landsvirkjun, Iceland’s main electricity producer, is taking the Y2K issue very seriously. As the country’s grid is completely isolated, the hydro plants and geothermal units that supply much of its power must continue to operate without any interruptions over the millennium. A failure to produce electricity in Iceland’s severe winter weather could have disastrous consequences. The organisation has scoured its distribution management systems for potential Y2K problems, and has had to ensure that the speed governors at its hydroelectric plants were compatible.
Four years ago there would have been no need for this diligence, as Landsvirkjun employed mechanical or analogue speed governors with no date management capability. But a recent modernisation programme has replaced this old-fashioned type with Voith digital speed governors. The new technology now controls almost 57% of the country’s installed hydro output.
Digital speed governors use dates for additional monitoring functions, like the occurrence of a system failure or the calculation of operation time between two dates. Dates are also used by the system hardware in ways which are hidden from the end-user. Landsvirkjun therefore had to ensure that the Voith systems it had received were Y2K compliant.
A team of engineers was sent from Voith to look into possible problems linked to the Y2K issue. There are three main hardware models used in the governors marketed and manufactured by Voith. Each was analysed with the co-operation of the hardware component suppliers (the hardware comprised a main CPU board and peripheral liquid crystal display with its own OS), operating system software designers, application software designers and the designers of development tools used to customise functions. The correct use of dates (if any) in each part of the system had to be checked. After this, all the tests on dates identified as critical (9/9/99, the rollover 31/12/1999 to 01/01/2000, 29/02/2000) in operation, shutdown, standby or power off/power on transition were tested methodically and passed in Voith’s laboratory. (For more details on Y2K issues see IWP&DC May 1999, pp24-28).
An engineer at Voith said: ‘I already had experience of the Y2K issue. In 1984 I worked on a low cost speed governor system for a small hydro project in Luxembourg, in which there were already monitoring functions using the date given by the clock of the main CPU board micromac 5000. At that time I was wondering how long my system would function. I tried to set a distant future date and, surprise surprise, the system failed to give the right date. I solved the problem by writing a special routine and testing the transition to 2000. After that I remained sensitive to dates in my designs.’ Voith says it has made every effort to ensure the accuracy of the methods it uses to test its digital speed governors. However, because each hydro power station’s environment is different from Voith’s laboratory test environment, it is the customer’s responsibility to validate Y2K readiness of these products in their own environment. Real tests in generation conditions are difficult to organise, but Landsvirkjun did it at Burfell power house at the beginning of 1999. Further tests have been made in Steingrimsstödd and Laxa power stations.
All equipment passed the tests. Some protection relays were not testable, so their software was modified by their original manufacturer.
The following speed governing systems have been modernised with Voith digital speed governors: Burfell (6x48MW Francis), Sigalda (3x50MW Francis), Steingrimsstödd (2×13.5MW Kaplan), Irafoss (3x15MW Francis), Ljosafoss (3x5MW), Laxa II (1×9 MW), and Laxa III (2x7MW).
For all of the modernised systems Voith has used a standard governor type, simplifying the maintenance and training efforts of Landsvirkjun’s teams. In most cases the existing oil pressure has not been changed, limiting the cost of the modernisation to the replacement of the speed governor cubicle and actuator.