Control Optimization for Multiple Gas Turbine Driven Compressors

Many gas compressor stations use multiple gas turbine driven centrifugal compressors. In many instances, the units are not identical. The challenge is to control the units such, that certain operational parameters, for example fuel consumption, are optimized. The control system has to rely on measurable parameters. The system has to be reliable even if parameters that are not directly measured change during operation. For practical use, the two methods available are to control all compressors for the same turndown, or to control all gas turbines for the same load. This methodology can be derived and discussed for the case of identical machines, and will be expanded for the case where the compressors and their drivers are not identical. The paper describes a variety of optimization methods, starting with a simple algorithm, then comparing equalization methods, and finally illustration the capability of methods that combine turbomachinery optimization and the optimization of pipeline hydraulics.