Maximum closed-loop peak

The closed-loop responses to a step change in x fron 0.2 to 0.4 are shown in Fig. 15.13. The set point is the nominal value, Xsp = 0.34. The static feedforward controller for cases (a) and (b) are equivalent and thus produce identical responses. The comparison in part (a) of Fig. 15.1 shows that the dynamic feedforward controller is superior to the static feedforward controller, because it provides a better approximation to the ideal feedforward controller of Eq. 15-33. The PI controller in part (b) of Fig. 15.13 produces a larger maximum deviation than the dynamic feedforward controller. The combined feedforward-feedback control system of part (d) results in better performance than the PI controller, because it has a much smaller maximum deviation and lAE value. The peak in the response at approximately t = 13 min in Fig. 15.13b is a consequence of the x measurement time delay. 

The frequency response of the closed loop transfer function of thermal-hydraulic stability for the average power channel of the Super LWR at 100% power operation with different mesh sizes (assuming an orifice pressure drop coefficient of 10) is shown in Figs. 5.28 and 5.29. A resonant peak is observed at the frequency of about 2.5 rad/s due to the flow feedback effect. A similar resonant peak is observed at the frequency of about 4 rad/s for the 100% maximum power channel as shown in Figs. 5.30 and 5.31. These resonant frequencies are consistent with the corresponding coolant transit time (about 1.6 s for the average power channel and about 1.0 s for the maximum power one). 

If the inductance L in the simple circuit shown in Fig. 4.13 has a d.c. resistance of 100 Q, the current through it with the switch closed is 0.24 A. Opening the switch sets the charge in the LC loop oscillating, and the peak instantaneous current is 0.24 A. Because the maximum energy stored in the capacitor (jCU2) must be equal to that stored in the inductor (jLI2), it follows that... 

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