A study to develop a linear quadratic controller for a ship central cooling system
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In this study, a linear quadratic (LQ) controller was developed and applied to maintain the desired freshwater outlet temper-ature, efficiently operate the seawater (SW) pump rotational speed, and effectively regulate the three-way valve opening in response to step disturbances. A mathematical model of the central cooling system was established to integrate the two controllers. The state-space equation of the mathematical model was linearized to facilitate controller development. The voltage frequency of the SW pump motor and three-way valve opening degree were selected as the two primary inputs of the system control. In contrast, the heat exchanger (HEX) and three-way valve outlet temperatures were the primary outputs of the control system. To design the LQ controller, the input control vector that minimized the performance index by incorporating specific weighting matrices was determined. The resulting LQ controller with an integrator was developed and tested through control performance simulations. The simulation results revealed that the proposed controller controlled the freshwater outlet temperature with minimal overshoot, efficiently controlled the SW pump rota-tional speed, and effectively controlled the three-way valve opening against step disturbances. The proposed LQ controller for central cooling systems offers a refined approach for efficiently controlling ship central cooling systems.
Abstract
In this study, a linear quadratic (LQ) controller was developed and applied to maintain the desired freshwater outlet temper-ature, efficiently operate the seawater (SW) pump rotational speed, and effectively regulate the three-way valve opening in response to step disturbances. A mathematical model of the central cooling system was established to integrate the two controllers. The state-space equation of the mathematical model was linearized to facilitate controller development. The voltage frequency of the SW pump motor and three-way valve opening degree were selected as the two primary inputs of the system control. In contrast, the heat exchanger (HEX) and three-way valve outlet temperatures were the primary outputs of the control system. To design the LQ controller, the input control vector that minimized the performance index by incorporating specific weighting matrices was determined. The resulting LQ controller with an integrator was developed and tested through control performance simulations. The simulation results revealed that the proposed controller controlled the freshwater outlet temperature with minimal overshoot, efficiently controlled the SW pump rota-tional speed, and effectively controlled the three-way valve opening against step disturbances. The proposed LQ controller for central cooling systems offers a refined approach for efficiently controlling ship central cooling systems.
참고문헌 (18)
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