Ensuring Stable Circuit Conditions of Direct Cycle Helium Gas Turbine System

The choice of compressor characteristics of turbogroups is of decisive importance for the stable behavior of circuits during transients. It is shown how compressor surge at dangerous speeds during rapid shutdown can be suppressed by combining a compressor having a steep characteristic and low reaction with a compressor having a flat characteristic and high reaction. This combination is also well suited with respect to loss of load and startup. In addition, very favourable properties are obtained during positive load steps executed for the purpose of frequency support. Beside providing a machine design with inherent safety, a control system must be supplied which is not only redundant but exhibits inherent safety from malfunction and failures which could endanger the power plant. Because of the importance of these problems, the design and operation of such a control system are presented in this paper.