Showing 5 results for Photovoltaic System
A. Gharaveisi, G. A. Heydari, Z. Yousofi,
Volume 10, Issue 3 (9-2014)
Abstract
In this paper, the Vector Based Swarm Optimization method is used for designing an optimal controller for the maximum power point tracker of a stand-alone PV System. The proposed algorithm is executed on vectors in a multi-dimension vector space. These vectors by appropriated orientation converge to a global optimum while the algorithm runs. The Remarkable point of the VBSO algorithm is how using completely random coefficients have good influence on algorithm performance. The generated energy is delivered to a boost converter including a resistive load. The duty cycle of the converter’s switch is determined in order to minimize generated power deviation, relative to PV voltage.
F. Hasanzad, H. Rastegar, G. B. Gharehpetian, M. Pichan,
Volume 13, Issue 2 (6-2017)
Abstract
Photovoltaic systems integrated to the grid have received considerable attention around the world. They can be connected to the electrical grid via galvanic isolation (transformer) or without it (transformerless). Despite making galvanic isolation, low frequency transformer increases size, cost and losses. On the other hand, transformerless PV systems increase the leakage current (common-mode current, (CMC)) through the parasitic capacitors of the PV array. Inverter topology and switching technique are the most important parameters the leakage current depends on. As there is no need to extra hardware for switching scheme modification, it's an economical method for reducing leakage current. This paper evaluates the effect of different space vector modulation techniques on leakage current for a two-level three-phase four-leg inverter used in PV system. It proposes an efficient space vector modulation method which decreases the leakage current to below the quantity specified in VDE-0126-1-1 standard. furthermore, some other characteristics of the space vector modulation schemes that have not been significantly discussed for four-leg inverter, are considered, such as, modulation index, switching actions per period, common-mode voltage (CMV), and total harmonic distortion (THD). An extend software simulation using MATLAB/Simulink is performed to verify the effectiveness of the modulation technique.
M. Ghani Varzaneh, A. Rajaei, M. Fakhraei,
Volume 13, Issue 3 (9-2017)
Abstract
This paper presents a new structure to provide the ability for power sharing of two Z-source inverters. According to the operation principles of Z-source inverters, only one input source supplies the circuit, which is a limitation particularly for the stand alone systems feeded by limited output power such as photovoltaics and feul cells. Furthermore; if one source fails to supply, the load can't be supplied. This paper covers those via interconnection of impedance network of two Z-source inverters. The operating principles of the proposed topology for the stand-alone and power sharing conditions are described and the relations are derived. The topology is simulated, which the results verify the theoretical analysis and well performance of the system.
S. M. Hoseini, N. Vasegh, A. Zangeneh,
Volume 16, Issue 2 (6-2020)
Abstract
In this paper, a robust local controller has been designed to balance the power for distributed energy resources (DERs) in an islanded microgrid. Three different DER types are considered in this study; photovoltaic systems, battery energy storage systems, and synchronous generators. Since DER dynamics are nonlinear and uncertain, which may destabilize the power system or decrease the performance, distributed robust nonlinear controllers are designed for the DERs. They are based on the Lyapunov stabilization theory and super-twisting integral sliding mode control which guarantees system stability and optimality simultaneously. The reference signals for each DER are generated by a supervisory controller as a power management system. The controllers proposed in this work are robust, have fast response times, and most importantly, the control signals satisfy physical system constraints. The designed controller stability and effectiveness are also verified using numerical simulations.
N. Danapour, E. Akbari, M. Tarafdar-Hagh,
Volume 18, Issue 3 (9-2022)
Abstract
In electricity generation through photovoltaic cells, efficient inverters are required to inject the generated power into the grid. Among the inverters connected to the grid, current source inverters despite their advantages are used less than voltage source ones. Different circuits are presented for these converters. In this paper, several power circuit topologies of the current source inverters, which are an interface between solar panels and the grid, are reviewed. Also, the inverters are compared from the point of some indexes like efficiency, voltage transmission ratio, total harmonic distortion, leakage currents, and their reduction methods. The importance of these indexes is investigated too. Categorization is for full-bridge inverters and special structures groups. The first group includes the conventional inverter, 4-leg inverter, CH7 CSI, H7 CSI, three-mode, and other structures. The second group consists of inverters with special structures and is independent of the conventional CSI. The summary of the studies is presented in a table.
