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Title: An expert system for the performance control of rotating machinery
Author: Pearson, William N.
Awarding Body: Edinburgh Napier University
Current Institution: Edinburgh Napier University
Date of Award: 2000
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This research presented in this thesis examines the application of feed forward neural networks to the performance control of a gas transmission compressor. It is estimated that a global saving in compressor fuel gas of 1% could save the production of 6 million tonnes of CO2 per year. Current compressor control philosophy pivots around prevention of surge or anti-surge control. Prevention of damage to high capital cost equipment is a key control driver but other factors such as environmental emissions restrictions require most efficient use of fuel. This requires reliable and accurate performance control. A steady state compressor model was developed. Actual compressor performance characteristics were used in the model and correlations were applied to determine the adiabatic head characteristics for changed process conditions. The techniques of neural network function approximation and pattern recognition were investigated. The use of neural networks can avoid the potential difficulties in specifying regression model coefficients. Neural networks can be readily re-trained, once a database is populated, to reflect changing characteristics of a compressor. Research into the use of neural networks to model compressor performance characteristics is described. A program of numerical testing was devised to assess the performance of neural networks. Testing was designed to evaluate training set size, signal noise, extrapolated data, random data and use of normalised compressor coefficient data on compressor speed estimates. Data sets were generated using the steady state compressor model. The results of the numerical testing are discussed. Established control paradigms are reviewed and the use of neural networks in control l'Iystems were identified. These were generally to be found in the areas of adaptive or model predictive control. Algorithms required to implement a novel compressor performance control scheme are described. A review of plant control hierarchies has identified how the Mdwme might be implemented. The performance control algorithm evaluates current !,!'Ocells load and suggests a new compressor speed or updates the neural network model. {'ornpressor speed can be predicted to approximately ± 2.5% using a neural network h,lt1l'd model predictive performance controller. Comparisons with previous work suggest l'1l1t 'IlUal global savings of 34 million tonnes of CO2 emissions per year. A generic, rotating machinery performance control expert system is proposed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QA76 Computer software Automatic control Control theory Natural gas Artificial intelligence