The main aim of the EU H2020 project EcoSwing was to demonstrate a technical readiness level of 6–7 for high-temperature superconducting (HTS) technology operating in a wind generator. To reach this goal, a full-scale synchronous HTS generator was successfully designed, built and field-tested in a 3.6 MW turbine. The generator has a rotor with 40 superconducting coils of 1.4 m long. The required >20 km of coated conductor was produced within the project’s time schedule. All coils were tested prior to assembly, with >90% of them behaving as expected. The technical readiness level of HTS coils was thus increased to level 7. Simultaneously, the maturing of cryogenic cooling technology over the last decade was illustrated by the several Gifford-McMahon cold-heads that were installed on-board the rotor and connected with the stationary compressors through a rotating coupling. The cryogenic system outperformed design expectations, enabling stable coil temperatures far below the design temperature of 30 K after only 14 d of cool-down. After ground-based testing at the IWES facility in Bremerhaven, Germany, the generator was installed on an existing turbine in Thyborøn, Denmark. Here, the generator reached the target power range and produced power for over 650 h of grid operation.
A uniform cantilever beam under the effect of a time-periodic axial force is investigated. The beam structure is discretized by a finite-element approach. The linearised equations of motion describing the planar bending vibrations of the beam structure lead to a system with time-periodic stiffness coefficients. The stability of the system is investigated by a numerical method based on Floquet's theorem and an analytical approach resulting from a first-order perturbation. It is demonstrated that the parametrically excited beam structure exhibits enhanced damping properties, when excited near a specific parametric combination resonance frequency. A certain level of the forcing amplitude has to be exceeded to achieve the damping effect. Upon exceeding this value, the additional artificial damping provided to the beam is significant and works best for suppression of vibrations of the first vibrational mode of the cantilever beam.
The joints ensure the joint performance of the load carrying structural systems and they are the most responsible and important elements. Keyed joints are widely used in construction. They are characterized by an increased resistance to shear. On these grounds the structural concepts of keyed joints need further improvement. The article presents the research results of experimental test pieces five series in the form of single keys and one-keyed joints. Those samples have been tested in Poltava National Technical Yuriy Kondratyuk University. Follow strength factors have been varied: geometric parameters of joints (depth, height, width) and their ratio; angle of support surface (rectangular, trapezoidal and triangular key); level of compression; reinforcement (quality of reinforcement and the nature of its location); jointing width. The samples were made of heavyweight , expanded clay and fibre concrete. The experiments program includes influence study both of one of these factors and their combinations. The deformations, nature of failure, the ultimate load have been studied. Structural parameters of keyed joints which ensure the efficient behaviour have been installed.
In this paper a digital numerical simulation is carried out in which active magnetic bearings (AMB) are applied to control nonlinear and non-synchronous vibrations of a rigid rotor excited by non-conservative cross-coupling mechanisms. Through an adaptive control algorithm of the AMB-controller, unknown cross-coupling parameters of a rotor are estimated on-line by a standard least square estimator along with a time-varying so-called forgetting factor. The parameters of the AMB controller are adapted in order to compensate the cross-coupling effects and to stabilize the rotor system. Transient cross coupling response characteristics are calculated by numerical simulation of a rigid rotor supported by two active magnetic bearings. With this kind of control strategy the stability of the system can be guaranteed for much higher values of cross-coupling coefficients than with common non-adaptive feedback controllers, designed with pole placement or least square algorithms.
In this paper a digital numerical simulation is carried out in which active magnetic bearings (AMB) are applied to control nonlinear and nonsynchronous vibrations of a rigid rotor excited by nonconservative cross-coupling mechanisms. Through an adaptive control algorithm of the AMB controller, unknown cross-coupling parameters of a rotor are estimated on-line by a standard least-square estimator along with a time-varying so-called forgetting factor. The parameters of the AMB controller are adapted in order to compensate for the cross-coupling effects and to stabilize the rotor system. Transient cross-coupling response characteristics are calculated by numerical simulation of a rigid rotor supported by two active magnetic bearings. With this kind of control strategy, the stability of the system can be guaranteed for much higher values of cross-coupling coefficients than with common nonadaptive feedback controllers, designed with pole placement or least square algorithms.
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