Dual Control Structure Research Articles

Marine Wind Turbine PID-PID Torque Control with Vibration Reduction

Marine turbines are an alternative for the production of clean energy in countries where the use of land turbines is limited. However, these systems, especially floating turbines, present a series of control challenges due to their non-linear dynamics and strong wind and wave loads. In this work, a dual control architecture is proposed consisting of two conventional Proportional-Integral-Derivate (PID) controllers that have been tuned with genetic algorithms. One of them is responsible for achieving maximum power in the operating region where torque control is applied, and the other tries to reduce the oscillations of the turbine that cause its efficiency to decrease and produce structural fatigue. Furthermore, the benefits of including the gain scheduling based on wind speed in this dual structure have been studied. This dual control structure has been shown in simulation to be useful for both objectives.

Dual Control Structure of Modular Multilevel Converters for Power System Support

This paper presents an analysis of two philosophies to control the modular multilevel converter (MMC). Most MMC control strategies are based on the philosophy used in the traditional voltage-source converter, in which the dc-bus voltage is controlled through the ac-side power; this approach is referred to here as the classical control approach. Because the MMC has an additional degree of freedom, an alternative control philosophy has recently been proposed, in which the dc-bus voltage is controlled through the dc-side power. In this paper, a comparison of these control approaches is presented and their main differences are described. Considering the increasing requirements imposed by system operators to converter-interfaced systems, guidelines are also given to provide supplementary services such as virtual inertia provision, short-term frequency support, virtual capacitor emulation, and oscillation damping. The provided insights are useful for selecting the appropriate MMC control strategy and for developing new supplementary controls for facilities based on the MMC topology.

Modeling and controlling of quadrotor aerial vehicle equipped with a gripper

Arm mounted unmanned aerial vehicles provide more feasible and attractive solution to manipulate objects in remote areas where access to arm mounted ground vehicles is not possible. In this research, an under-actuated quadrotor unmanned aerial vehicle model equipped with gripper is utilized to grab objects from inaccessible locations. A dual control structure is proposed for controlling and stabilization of the moving unmanned aerial vehicle along with the motions of the gripper. The control structure consists of model reference adaptive control augmented with an optimal baseline controller. Although model reference adaptive control deals with the uncertainties as well as attitude controlling of unmanned aerial vehicle, baseline controller is utilized to control the gripper, remove unwanted constant errors and disturbances during arm movement. The proposed control structure is applied in 6-degree-of-freedom nonlinear model of a quadrotor unmanned aerial vehicle equipped with gripper having (2 degrees of freedom) robotic limb; it is applicable for the simulations to desired path of unmanned aerial vehicle and to grasp object. Moreover, the efficiency of the presented control structure is compared with optimal baseline controller. It is observed that the proposed control algorithm has good transient behavior, better robustness in the presence of continuous uncertainties and gripper movement involved in the model of unmanned aerial vehicle.

Design and Control of the Monoisopropylamine Process

The monoisopropylamine (MIPA) process provides an interesting example of plantwide economic design optimization and plantwide control. The process consists of a tubular reactor and three distillation columns. There are both gas and liquid recycles. Fresh feed streams of isopropyl alcohol and ammonia are introduced into the process. The desired products are MIPA and water. An undesirable byproduct of di-isopropylamine (DIPA) is also produced and is recycled to extinction since its formation reaction is reversible. An excess of ammonia in the reactor inhibits the DIPA reaction, so ammonia is also recycled. The purpose of this paper is to present the details of the process for use by other workers as a test case for use in plantwide design and control studies. A heuristic economic optimum design and a control structure are developed. The process illustrates the classical design trade-off between reactor costs versus separation costs. In addition, the process has two recycles, which are both distillate products from different distillation columns, and this leads to another trade-off. Using more ammonia recycle produces less DIPA recycle. So the optimum design must balance the separation costs of the two recycles. Two of the distillation columns can be effectively controlled using a single temperature and a reflux-to-feed ratio control structure. The third column requires a dual control structure ratio (one temperature and one composition).

Pythagorean-hodograph ovals of constant width

A constructive geometric approach to rational ovals and rosettes of constant width formed by piecewise rational PH curves is presented. We propose two main constructions. The first construction, models with rational PH curves of algebraic class 3 (T-quartics) and is based on the fact that T-quartics are exactly the involutes of T-cubic curves. The second construction, models with rational PH curves of algebraic class m > 4 and is based on the dual control structure of offsets of rational PH curves.