A small scale vertical axis wind turbine (VAWT) with axial flux permanent magnet (AFPM) generator has been designed and magnetic levitation method is used to increase the efficiency of this type of wind turbine [1]. Magnetic levitation is inserted by using rare earth permanent magnets, the repelling force of magnets are used to suspend the rotating part of both turbine and generator. Moreover, design of simple generator which can easily drive without geared mechanism, lessen cost and the complexity of the system by reducing the quantity of driving components. Three phase output is obtained from designed generator which is converted into direct current through three-phase rectifier to charge the batteries. The performance of proposed prototype is also tested experimentally. The turbine performs as predicted by the design process.

In this paper, a new method is proposed to identify the health condition of composite insulators through investigating the leakage current (LC) along with the electric potential (EP) and electric field stress (EFS) profiles. In this regard, variations of the LC harmonics and the distribution profiles of the EP and EFS are investigated through series of experimental and simulation analyses conducted on composite insulators under various environmental and pollution conditions. Fast Fourier Transform and COMSOL-Multiphysics environment are utilized to analyze this variation. Results reveal a strong correlation between the LC harmonics and the insulator health condition. A new diagnostic criticality index based on the third to the fifth harmonic ratio of the insulator LC is proposed to quantify the composite insulator criticality and predict the likelihood of flashover occurrence. The EP and EFS analysis can be used to provide a complimentary diagnosis to the insulator health state under severe pollution and humidity conditions. The proposed analysis enables the transmission line network operator to get an insight into the insulators' functional status and thus improving the network reliability through avoiding insulator failure and adopting a proper condition-based maintenance scheme.

Transverse flux permanent magnet linear generator (TF-PMLG) is widely used in direct drive wave energy converter (DD-WEC) because of its high power density. Traditional transverse flux machine (TFM) is designed and built in form of translator-PM. But translator-PM configuration needs a large amount of PM and the cost is high in long stroke application, like DD-WEC. Recently, the stator-PM linear machines have gained more attention for reducing the PM volume and improving the generator performances under low-speed conditions. In this paper, a novel stator-PM TF-PMLG for DD-WEC has been proposed. The fundamental configuration and operation principle of the generator are illustrated. Then, the expressions of the back EMF and the electromagnetic thrust are derived by magnetic circuit analysis. Main dimension parameters, such as PM thickness, central angle of the outer stator shoe and pole pitch are determined and optimized based on finite element analysis (FEA). This topology has advantages of low PM consumption and high power density, and is a suitable candidate for long stroke applications, like DD-WEC, in which a high power per PM volume is usually needed to reduce the amount of permanent magnet and ensure high power density.

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