Using the linear block diagram

A further use for the control engineer is that the linear analysis allows him to use frequency response methods for control system design. The fact that the system has been broken down into subsystems also means that any nonlinearities such as deadzone that are known to exist may be introduced easily into the block diagram layout and represented by describing functions. 

It will be clear from the detailed analysis of a realistic process system that analytic linearization is unlikely to be a trivial exercise. The amount of detailed mathematical analysis often needed means that it cannot be recommended for every case. And certainly it should never be regarded as an alternative to full, nonlinear simulation. However, if the control engineer does carry out such a linear, block-diagram analysis and 

The reader interested in more details of the industrial problem on which the worked example was based is referred to this chapter s references concerning the control of a boiler feedwater system. 

Harrison, T.A. and Thomas, P.J. (1986). Dynamic interactions between recirculation boilers connected in parallel. Boiler Dynamics and Control in Nuclear Power Stations 3, Proceedings of the Third International Conference, Harrogate, 21-25 October. 1985, Paper 18, British Nuclear Energy Society. 

Holywell, P.D. (1986). Multivariable control system analysis of a drum level control system. Nuclear Energy, 25, 163-168. 

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