One of the major challenges today is assessing the suitability of PV (photovoltaic) systems' installations on buildings' roofs regarding the received solar irradiance. The availability of aerial laser-scanning, namely LiDAR (Light Detection And Ranging), means that assessment can be performed automatically over large-scale urban areas in high accuracy by considering surfaces' topographies, long-term direct and diffuse irradiance measurements, and influences of shadowing. The solar potential metric was introduced for this purpose, however it fails to provide any insights into the production of electrical energy by a specific PV system. Hence, the PV potential metric can be used that integrates received instantaneous irradiance which is then multiplied by the PV system's efficiency characteristics. Many existing PV potential metrics over LiDAR data consider the PV modules' efficiencies to be constant, when in reality they are nonlinear. This paper presents a novel PV potential estimation over LiDAR data, where the PV modules' and solar inverter's nonlinear efficiency characteristics are approximated by modelled functions. The estimated electrical energy production from buildings' roofs within an urban area was extensively analysed by comparing the constant and nonlinear efficiency characteristics of different PV module types and solar inverters. The obtained results were confirmed through measurements performed on an existing PV system.
COBISS.SI-ID: 17543702
This work deals with the differential evolution (DE) based method for simultaneous identification of the electric, magnetic and mechanical subsystem parameters of a line-start interior permanent magnet synchronous motor (LSIPMSM). The parameters are determined in the optimization procedure using the dynamic model of the LSIPMSM, the time behavior of voltages, currents and speed measured on the tested LSIPMSM, and the DE which is applied as the optimization tool. During the optimization procedure the DE changes the parameters of the LSIPMSM dynamic model in such a way that the differences between the measured and calculated time behavior of individual state variables is minimized. The paper focuses on the objective function definition, constraints settings for individual parameters, normalization of parameters, and above all the test and measurement procedures performed on the LSIPMSM, which all together make possible to determine the LSIPMSM dynamic model parameters valid for a broad range of operation, and thus, ensuring proper evaluation of the LSIPMSM%s line-starting capability. Some of the LSIPMSM parameters that can be determined by finite element analysis and experimental methods are compared to the values obtained by the DE, thus validating the DE based approach.
COBISS.SI-ID: 17638166
The paper proposes an IM torque control derived from the model in the stator current vector reference frame. The required torque is produced by simultaneously manipulating the magnitude and the rotation speed of the statorcurrent vector thus forcing the rotor flux linkage vector to change implicitly in such a way that overall stability is preserved. Additional control features include maximal torque per ampere ratio in steady state and almost perfect command tracking even if the machine is magnetically saturated.The control adopts a cascaded structure and is based on a partial dynamic inversion of the reduced model that assures existence and uniqueness of the inverse mapping between the required torque, the rotor flux linkage vector and the stator current vector. Singularity at zero rotor flux linkage represents no restriction for the control performance in the admissible machine operating range. The implementation of the proposed control requires the estimation of the torque producing rotor flux component and cascaded stator current controllers. Experimental results confirm the key expectations and show the potential and benefits of the proposed control schemes.
COBISS.SI-ID: 16731414
In this paper, various newmodels of double-regulated Kaplan turbines are proposed, whose parameters are determinedon the basis of field measurement data acquired during normal operating conditions. The model being identified is an extensionof the nonlinear single-regulated turbine model obtained throughan approximation function that defines the relationship between the wicket gate opening and runner blades angle. To determine the unknown parameters of the approximation function, a stochastic search algorithm called differential evolution (DE) is used. This paper focuses on the progressive development of the DE algorithm based methods that are applied to determine different forms of the approximation functions, until an optimal form is attained that ensures the best possible agreement between the measured and calculated responses.
COBISS.SI-ID: 17377302
The roof surfaces within urban areas are constantly attracting interest regarding the installation of photovoltaic systems. These systems can improve self-sufficiency of electricity supply, and can help to decrease the emissions of greenhouse gases throughout urban areas. Unfortunately, some roof surfaces are unsuitable for installing photovoltaic systems. This presented work deals with the rating of roofsurfaces within urban areas regarding their solarpotential and suitability for the installation of photovoltaic systems. The solarpotential of a roofćs surface is determined by a new method that combines extracted urban topography from LiDAR data with the pyranometer measurements of global and diffuse solar irradiances. Heuristic annual vegetation shadowing and a multi-resolution shadowing model, complete the proposed method. The significance of different influential factors (e.g. shadowing) was analysed extensively. A comparison between the results obtained by the proposed method and measurements performed on an actual PV power plant showed a correlation agreement of 97.4%.
COBISS.SI-ID: 16262934