As the correct solution of any problem depends primarily on a true understanding of what the problem really is, and wherein lies its difficulty it is profitable to pause upon the threshold of the subject to consider first in a more general way its real nature; the causes which might impede sound practice; the conditions on which success or failure depends - in order to develop a clear mental perspective to prevent confusion of the obvious with the important, and the obscure and remote with the unimportant.
It is as well to point out at once that the demand for electricity in South East Queensland is met by virtually an all-thermal system, raising steam from sub-bituminous coal. The area has no great firm hydro-electric resources, and the cost of thermal generation has been kept fairly cheap. Further, most reliable authorities have expressed the considered opinion that nuclear energy will not prove economical here for approximately the next ten years.
Since the consumer load demand is still increasing in South East Queensland every year, the existing generating equipment will need to be reinforced if the Supply Authorities are to maintain their present high sense of responsibility to the consumers. To permit replacement of unreliable older plant, also at the same time to make more efficient operation, and maintenance, of the power stations possible, the programme of extensions needs to be carefully thought out and proceeded with along reliable as well as economical engineering lines.
Future planning for generating capacity is, of course, under close and constant review by both Supply Authorities and The State Electricity Commission of Queensland. The Technical Sub-Committee appointed to investigate this matter secured from various contractors certain basic data in regard to new equipment, and acknowledgement of the use of this information is expressed with thanks.
Recommendations for extensions will be influenced to a large extent by the possible provisions of capital. Also the use to which the plant will be put throughout the various financial years has an important effect on the economics of generation.
A truly integrated generating system should be further developed in South East Queensland to enable full value to be obtained from all the attendant economic potentialities, such as the ability to exploit inherent savings in maximum size units both in turbo-alternators and boilers, the operation of the most economical units in the most economical region, and at maximum Plant-Use Factor in the case of new units. The Plant Forecast programme has been set up on the basis of examples of other fully interconnected systems being followed. This would be a gradual development over a number of years, but the foundations should be laid now.
There is no practical and simple formula to compare directly the combined performance of different arrangements of boilers, steam headers, turbines, alternators, auxiliaries, condensers, river sites, coal field sites, and cooling towers. However, the size of the combined systems in South East Queensland restricts the choice, and it becomes necessary to make relatively few performance studies of intelligently selected combinations in assessing the merits and disadvantages of sound schemes.
No matter how detailed the plant selection study may be, the figures cannot be taken too literally since they are founded on forecasts; fundamental components of the cost elements are moving all the time, so that no one solution will be correct for very long. However, the calculations are useful as a guide.
Once the original selection of site and equipment has been finalised, -and the station design determined, its operating duty is decided for practically the rest of its working life. Daily loading of all stations on the properly planned interconnected system has to be scheduled to give the best possible overall running economy. Fundamentally this will be based on the well known incremental rate methods.
Incremental loading requires plant studies and in many cases the carrying out of exhaustive thermal plant tests to determine actual performance on a thermal input/output basis. All the plant in the power stations will be subject to deterioration of performance with operating hours, some sections, for example in the boiler house, being more susceptible than others. As a basis for use in assessing controllable losses, the official acceptance test with all components as clean as can be, provides the best possible data. It then remains for the plant to be operated and maintained so that it always runs as near these best conditions as possible, in order that optimum results are obtained from merit order loading of the plant.
Turbo-alternator plant installed with suitable stand-by auxiliaries is recognized as being the most trouble free in modern power stations. Probability research indicates an average turbo-alternator unit failure of once every seven years. However, this factor can prove a liability in times of trouble due to the operators becoming accustomed to rely on automatic controls which can lead to unfamiliarity with what is going on inside the various parts of the plant. Typical cases representative of the more important plant at present installed in South East Queensland have been considered with this outlook in mind. The doctrine being that it is better to be ahead of trouble than trying to catch up with it.
In regard to the Sections on Boilers, Turbo-alternators and Condensers - which to a large extent have been standardized in the area - manufacturer's handbooks have been used on occasions to give authenticity to the explanations being made.
Throughout the preparation of this thesis the need to bring forward work in the field of professional engineering for which the candidate can claim originality has always been kept in mind. In particular, to the best of the writer's belief, the Sub-Sections in Section I commenting on System Forecasts, Replacement of Older Plant, Plant-Use Factor, Design and Layout, Incremental Heat Rate Calculations and Tests on Practical Loading Methods, come within this category. The other material offered in Section I has been developed largely from reading and investigation. Section II sets out practical testing procedures, tried and proved at the power station with which the writer is associated. Section III refers to Turbo-alternators, and here it is believed that the comments on alternator control have not been published before. It seems impossible to write about thermal power stations without mentioning the Condensing Plant (Section IV), and the Steam Generating Plant (Section V) , in some detail. The overall performance of the station - a most important operational consideration - is very closely linked up with both these sections of the plant, and many of the submissions here have been founded on the writer's own observations.
These then are some of the problems and thoughts on which this thesis is based. The material offered has been sectionalized, since the subject of "Power Station Operation and Maintenance - South East Queensland" has many parts, of which it is hoped the main ones have been covered in a suitable manner.