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A common method for controlling a group of parallel converters in decentralized control strategy structure in an island microgrid, the use is the droop-down characteristics of frequency ω-P and voltage E-Q. However, the problem with using this method is that the reactive power is not properly distributed (in proportion to the capacity of the micronutrients) between the micronutrients, which may lead to overload in the converters. Microgrids may also suffer from dynamic stability problems such as power fluctuations, which can be increased by switching between active and reactive power control. To avoid this problem, the X / R ratio of transmission lines is an important parameter that should be carefully considered in the design of micronutrient controllers. By linearizing and simplifying conditions, the control system conversion function model becomes a single input-single output system, which is efficient enough to show the relationship between control parameters such as slope of droop characteristics and derivative sentences, virtual impedance, and voltage controllers. Using this model, stability conditions for different parameters are analyzed. Also, to improve power distribution stability, common droop strategies are modified by adjusting the slope as well as adding nonlinear sentence sections. This approach reduces the coupling between active and reactive power control and reduces the dependence of power distribution on grid parameters such as the X / R ratio. To evaluate the reliability of the proposed model, the simulation results in a sample island microgrid in MATLAB software are presented.

Service life and safety of a steel jacket platform is influenced by vibrations generated by environmental loads, waves and winds. Vibrations of the structure and deck may cause fatigue in the structural elements and joints. Also may disrupt the operation of the drilling equipment and facilities as well as the operation of the platform. Therefore, the main aim of this research is to control the vibrations of the steel jacket platform through shape memory alloys dampers. Shape memory alloys have two important properties of shape memory as well as superelastic behavior and are quite suitable for damping applications. In these alloys, crystal structures transition from the austenite to the martensite phase, and vice versa are accompanied by the energy dissipation. In this research, a 90m steel jacket structure equipped with SMA dampers installed in 80m water depth has been modeled as a multi-degree-of-freedom system and analyzed under the time history of wave loads. For solving the differential equations of system vibration and modeling the hysteresis behavior of the shape memory alloys elements, the direct integration alpha method and multi-linear idealized constitutive model have been used, respectively. Jacket platform equipped with the shape memory alloys dampers shows the better result with 42% reduction in deck displacement, 62% reduction in deck acceleration and 32% reduction in shear force of platform base.

Shape memory alloys (SMAs) are a special kind of smart materials with an intrinsic shape memory effect. This characteristic brings up SMAs as an actuator in dynamic mechanisms. These materials can recover their initial length under special thermal operations. This paper deals with fuzzy-PID control of contrary mechanisms actuating with a pair of SMA wires. The Brinson model combined with Elahinia’, s conditions is employed to describe the phase transformation models. By combining Newton's second law, transformation models, heat transfer, and strain relations, the governing equations of the contrary mechanism are derived. Due to the nonlinear behavior of SMA actuators, the non-model-based controllers are preferred compared to the model-based ones. Therefore, the fuzzy-PID control method is employed to control the position of the closed-loop system. The fuzzy rules are defined such that the coefficients of the PID controller are tuned according to the system response. Both numerical and experimental results are provided to illustrate the effectiveness of the proposed approach. It will be shown that under the proposed method, the tracking error will converge to zero asymptotically.

Shape Memory Alloy (SMA) wires are currently employed in robotics as actuators of prosthetic limbsand medical equipment due to advantages such as reducing the size in the application, high power-toweight ratio and elimination of complex transmission systems. In this paper, a fuzzy control system hasbeen designed and implemented for an artificial finger using the SMA actuators. This robotic finger hasbeen designed and modeled with three revolute joints and three SMA wires as the tendon in order foradduction of each phalange of the finger and torsional springs were used to restore them to their originalpositions. The dynamic model of the finger has been simulated in MATLAB/Simulation. Based on thesimulation results, optimal choices of parameters and system features have been obtained and aprototype of finger has been built and tested. Gains of the controllers are set so that the current appliedto SMA wires has minimum overshoot and the output of the system has minimal time to achievestability. The comparison between the simulation results and the actual measured data show that thesimulated model is accurate.