Modeling of PV Module and DC/DC Converter Assembly for the Analysis of Induced Transient Response Due to Nearby Lightning Strike

Photovoltaic (PV) systems are subject to nearby lightning strikes that can contribute to extremely high induced overvoltage transients. Recently, the authors introduced a 3D semi-analytical method to study the electromagnetic transients caused by these strikes in a PV module. In the present paper we develop an improved model of the PV module that: (a) takes into account high-frequency effects by modelling capacitive and inductive couplings; (b) considers the electrical insulation characteristics of the module; (c) includes the connection to a DC/DC converter. The whole process involves three major steps, i.e., the magnetic-field computation, the evaluation of both common-mode- and differential-mode-induced voltages across the PV module, and the use of the calculated voltages as input to a lumped equivalent circuit of the PV module connected to the DC/DC converter. In such a framework, the influence of the PV operating condition on the resulting electrical stresses is assessed; moreover, the relevance or insignificance of some parameters, such as the module insulation or the frame material, is demonstrated. Finally, results show that the induced overvoltage are highly dependent both on the grounding of the conducting parts and on the external conditions such as lightning current waveforms and lightning channel (LC) geometry.

SEISMIC REACTION OF NONLINEAR SYSTEM OF SEISMIC DEFENSE WITH KINEMATIC SUPPORTS

Objectives. The aim of the study is to obtain formulae for calculating probability of seismic response characteristics of nonlinear seismic isolation system with the specified function "force-shifting", characteristic of seismic isolation system with kinematic pillars and score the effectiveness of this system of seismic isolation in multi-storey buildings.Method. The studies were performed analytical techniques and numerical method of statistical tests.Result. Analytical expressions to calculate the mean square value of one massive seismic isolation system with displacement kinematic pillars and the effectiveness of the application of graphs of kinematic seismic isolation bearings for multi-storey buildings based on the results of numerical experiments using the method of statistical tests.Conclusion. Application of kinematic supports, with "power-move" described by the specified in the work of a non-linear function, allows you to reduce the seismic loads on buildings and distortions of floors 2 or more times. Kinematic bases are more effective when high-frequency effects and in the buildings of the constructive solution of a height of not more than 5 floors.

Output Power Limit in Energy Harvesting Systems Based on Magnetic Induction Incorporating High-Frequency Effects

Wireless power transfer systems based on magnetic induction are usually modeled using the magneto-quasi-static approximation, and by neglecting skin effects and radiation losses. These assumptions imply that the extracted power can grow unlimitedly by increasing frequency or coil size. To bridge this gap, this work proposes general expression for the actual received power of magnetic induction-based energy harvesting transducer, extracting power from a given ambient magnetic field, while accounting for the high-frequency effects. A primary result is that the receiver’s output power is inherently limited by radiation losses at high frequencies and impaired by skin and proximity effects at medium frequencies. The approach provides a design tool for estimating the maximal power that can be delivered through a given transducer, and the optimal operating frequency.