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<p>The demand for extruded HVDC cable systems for higher voltages has been increasing in different fields. This demand comes from the need for higher transmission capacity in applications such as integration of wind power, power system interconnectors and connection of offshore oil and gas platforms to land. Prefabricated joints are used to connect the cable delivery lengths. If badly designed, the possibility of breakdown in the joints is higher than in other parts of the system because of the number of interfaces and triple points between different materials. Due to the huge potential costs and the down-time imposed to the system in case of a joint failure, the robustness of the joints is of great importance. Two main approaches in the design of prefabricated joints for extruded cables exist in which the more recent one takes advantage of the nonlinear properties of modern field grading materials. In this work, we have examined the design challenges with focus on robustness issues in a 150 kV classical joint design without field grading material. The results show that with this approach, there are serious robustness issues which are challenging to overcome without field grading material.</p>

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In this paper, the motion of a smart rigid-flexible satellite by considering large deformations for its flexible appendages in general planar motion is modeled. Therefore, the satellite can experience translational and rotational motions also its flexible appendages can vibrate arbitrarily in the motion plane. Two control forces perpendicular to each other and one control torque are responsible for controlling the motion of the satellite on the desired trajectories. Also, piezoelectric actuators and sensors suppress vibrations and estimate the transverse displacement of the satellite's flexible appendages, respectively. The coupled ordinary-partial differential equations of motion, equations of the sensors, and boundary conditions of the system are obtained using extended Hamilton's principle. Then, these equations are discretized using the Galerkin method. The discretized equations of motion are a set of coupled nonlinear ordinary differential equations due to the consideration of the large rotation angle of the satellite and large deformations for its flexible appendages. Adaptive super-twisting global nonlinear sliding mode controller is designed to satisfy the control objectives including position and attitude control, as well as suppressing vibrations of the flexible appendages in the presence of uncertainties and external disturbances. Eventually, numerical simulations are presented to illustrate the effectiveness of the proposed controller.