Control system design

With all of this knowledge and information available to the eontrol system designer, all that is left is to design the system. The first problem to be eneountered is that the 

Measurements of the eontrolled variables will be eontaminated with eleetrieal noise and disturbanee effeets. Some sensors will provide aeeurate and reliable data, others, beeause of diffieulties in measuring the output variable may produee highly random and almost irrelevant information. 

The design of a eontrol system is a mixture of teehnique and experienee. This book explains some tried and tested, and some more reeent approaehes, teehniques and methods available to the eontrol system designer. Experienee, however, only eomes with time. 

As described in Sect. 4.3.3, the reactor power of the Super LWR follows the turbine inlet flow rate through the reactivity feedback from the coolant temperature, rather than the pressure. Just as for PWRs, the reactor-following-turbine control may be applicable to the Super LWR however, the turbine-following-reactor control is applied here like in BWRs from the following reasons. 

Since the Super LWR does not use saturated steam, the main steam temperature changes with the power to flow rate ratio in the core. It needs to be kept constant in order to avoid too much thermal stress or thermal fatigue on the structures. Since the Super LWR has no superheaters that are utilized to control the main steam temperature as in FPPs, another method is needed. The analysis results described in Sect. 4.3.2 show that the main steam temperature is sensitive to the feedwater flow rate. Thus, the main steam temperature is controlled by regulating the feedwater flow rate. It is also suitable from the viewpoint of the safety principle of the Super LWR, i.e., keeping the core coolant flow rate (described in Sect. 6.2) because the feedwater flow rate indirectly follows the reactor power in this control method. The plant control system employed for the Super LWR is shown in Fig. 4.16. The plant control strategies of the Super LWR, PWRs, BWRs, and FPPs are compared in Table 4.3. 

The control system should be designed so that it does not generate divergent or continuous oscillations that exceed the permissible range. To do that, the parameters of the three control systems are tuned in the following sections. 

The Aspen Plus file is exported to Aspen Dynamics as a pressure-driven simulation after reflux-dram and base volumes are specified to provide 5 min of holdup when at 50% 

Notes (1) Faceplate shows heat input in metric (GJ/h). 

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Higher-order systems can be approximated by a first or second-order plus dead-time system for control system design. 

Pairing of Controlled and Manipulated Variables A key decision in multiloop-control-system design is the pairing of manipu-... 

General References Fisher, Batch Control Systems Design, Application,... 

Control analysi.s/design. Analysis of column balances and profiles to aid in control system design and operation. 

The nature of batch operations (unsteady-state), frequently involving manual intervention, creates significant issues pertaining to the design of control systems, design of operating procedures, and the interaction between the... 

Eisher, T. G. 1990. Batch Control Systems—Design, Application, and Implementation. Instrument Society of America. 

In control engineering, the way in which the system outputs respond in changes to the system inputs (i.e. the system response) is very important. The control system design engineer will attempt to evaluate the system response by determining a mathematical model for the system. Knowledge of the system inputs, together with the mathematical model, will allow the system outputs to be calculated. 

The selection of the PID controller parameters K, T[ and can be obtained using the classical control system design techniques described in Chapters 5 and 6. In the 1940s, when such tools were just being developed, Ziegler and Nichols (1942) devised two empirical methods for obtaining the controller parameters. These methods are still in use. 

The root locus method provides a very powerful tool for control system design. The objective is to shape the loci so that closed-loop poles can be placed in the. v-plane at positions that produce a transient response that meets a given performance specification. It should be noted that a root locus diagram does not provide information relating to steady-state response, so that steady-state errors may go undetected, unless checked by other means, i.e. time response. 

Control system design in the frequeney domain ean be undertaken using a purely tlieoretieal approaeli, or alternatively, using measurements taken from the eompon-ents in the eontrol loop. The teehnique allows transfer funetions of both the system elements and the eomplete system to be estimated, and a suitable eontroller/eompen-sator to be designed. 

State-space methods for control system design... 

The classical control system design techniques discussed in Chapters 5-7 are generally only applicable to... 

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