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Research Papers

# Full State Feedback Control of Steam Temperature in a Once-Through Direct Steam Generation Receiver Powered by a Paraboloidal Dish

[+] Author and Article Information
José I. Zapata

Solar Thermal Group,
Research School of Engineering
Australian National University,
Canberra 0200, Australia
e-mail: jose.zapata@anu.edu.au

The Hartman–Grobman theorem establishes that under certain conditions, the linear approximation has the same qualitative behavior as the nonlinear model near the operating point [15].

The subscript 0 indicates a specific value for a variable or sets of variables.

The system will converge to the equilibrium point $x0,y0$ when subject to $u0,v0$.

Other studies employing moving-boundary formulations of two-phase flow heat exchangers have obtained further model reductions that tend to preserve only the dominant behavior of the system [20,21].

Typical receiver heat losses in operation are approximately 45–60 kW [25].

Contributed by the Solar Energy Division of ASME for publication in the JOURNAL OF SOLAR ENERGY ENGINEERING: INCLUDING WIND ENERGY AND BUILDING ENERGY CONSERVATION. Manuscript received July 13, 2014; final manuscript received October 14, 2014; published online November 17, 2014. Assoc. Editor: Markus Eck.

J. Sol. Energy Eng 137(2), 021017 (Apr 01, 2015) (10 pages) Paper No: SOL-14-1202; doi: 10.1115/1.4028919 History: Received July 13, 2014; Revised October 14, 2014; Online November 17, 2014

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## Figures

Fig. 1

SG4 steam generation system diagram

Fig. 2

Signal diagram for the SG4 receiver outlet temperature controller. Thick arrows represent vector signals and thin arrows represent scalar signals.

Fig. 3

Complex plane diagram with dominant pole original and desired locations. Inset shows location of zero b7 and the pole/zero cancellation effect of the controller

Fig. 4

Simulated performance of the receiver outlet temperature controller, when transitioning from manual to automatic feed-water mass flow settings, and maintaining temperature during variations in DNI. Vertical dotted lines indicate the period where the temperature controller is active. (a) DNI. (b) Feed-water and outlet mass flow. (c) Receiver outlet temperature, with dotted lines to indicate 500 ± 15 °C. (d) Average receiver pressure. (e) Cumulative length of fluid regions, with respect to tube length (horizontal dotted line).

Fig. 5

Simulated performance of the receiver outlet temperature controller, when rejecting a triple drop to zero in DNI, akin a cloud disturbance. Simulations include the controlled without the AW and FF terms to show their effect on the controller. Simulations also include a PI controller with kp = 8×10-5 and ki = 2.22×10-7 for comparison. (a) DNI. (b) Feed-water and outlet mass flow. (c) Receiver outlet temperature, with dotted lines to indicate 500 ± 15 °C. (d) Average receiver pressure. (e) Cumulative length of fluid regions, with respect to tube length (horizontal dotted line).

Fig. 6

Unsuccessful attempts at experimental temperature control on 25 October 2013. Vertical dotted lines indicate periods when the temperature controller is engaged. (a) DNI. (b) Feed-water mass flow. (c) Receiver outlet temperature. Horizontal dotted lines indicate 500 ± 15 °C. (d) Inlet, outlet, and average receiver pressure. (e) Cumulative length of fluid regions, with respect to tube length (horizontal dotted line).

Fig. 7

Successful experimental test of temperature control on 30 October 2013. A vertical dotted line indicates when the temperature controller was engaged. (a) DNI. (b) Feed-water mass flow. (c) Receiver outlet temperature. Horizontal dotted lines indicate 500 ± 15 °C. (d) Inlet, outlet, and average receiver pressure. (e) Cumulative length of fluid regions, with respect to tube length (horizontal dotted line).

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