The higher solar energy urges to maximize the solar energy extraction and utilization. This paper aim is to propose a new technique for extending the daily extraction time via a proposed aggregated PV cell. This system idea is using group of the photovoltaic (PV) cells to behave as an interactive regulated cell according to the series or parallel connections, it can call it an aggregated cell. This can be realized by interactive switching system according to the single cell output voltage. Six 6V PV cells are used for configuring the proposed single aggregated 6V PV cell. The technique depends on both single-cell number and their interconnections pattern. Switching the panel connection between the fully series cells to full parallel ones according to either sunlight states or the single-cell output is automatically achieved using an interactive control system. This system includes a voltage sensor that implements the suitable switching pattern for the aggregated cell. The ripple voltages during both morning and afternoon low sun times, as well as due to any other reason such as the lower clouds are efficiently eliminated. The simulated and the experimental results show in a satisfactory agreement the proposed aggregated PV cell validation.
The power system self-healing concept needs accurate and reliable fault detection, classification, and location (FDCL). This research proposes a novel and robust FDCL approach for distribution networks (DNs) in proportion to self-healing requirements. The proposed algorithm utilized a discrete wavelet transform (DWT) to decompose the measured current and zero sequence current component of only one terminal (substation) to detect and classify all fault types with the identification of the faulted phase (s). The fault location is achieved by integrating DWT and support vector machine (SVM). The data for training were extracted using DWT and collected, and then SVM was trained to locate the faulted section. The simplicity of the applied approach, ignoring DG’s data that is merged into the system, reduced training data and time, ability to diagnose all fault types, and high accuracy are the most significant contributions. The proposed techniques are tested on IEEE 33 bus DN with two distributed generation (DG) units, which are simulated in MATLAB. The simulation results demonstrate that the proposed methods give more accurate and reliable results for diagnosing the faults (FDCL) of various fault sorts, DN size, and resistance levels.
In this paper, the operation and a complete design of the bootstrap circuit elements when firing a high-side MOSFET feeding an inductive load are introduced. The operation for both low-side and high-side cases are discussed with complete design and analysis of the bootstrap circuit elements. The effect of the bootstrap capacitor (BSC), diode, and resistance on the MOSFET switch for inductive loads at different frequencies and duty cycles including regular and SPWM are briefly analyzed. The current discontinuity is associated with higher losses, discontinued power output operation, and derated performance. The precise good design of the bootstrap circuit elements enables to improve the load current continuity in a specified frequency range of operation preventing the demerits of discontinuous operation. The effect of high-side implementation on extra harmonic content on the load is discussed including THD measurement of both applied voltages and currents.
This paper discusses the performance of a wind-driven doubly-fed induction generator when connected to the grid. The stator is directly connected to the grid, while the rotor side connection happens via a back-to-back converter. The performance and the steady-state analysis of the Doubly Fed Induction Generator (DFIG) when running at constant stator power and when running at constant stator current will be discussed. Laboratory experiments are performed using a testing bench for the Lucas-Nülle wind power system and the results are analyzed using Lucas-Nülle WindSim software. DFIG analysis and laboratory experiment performance were performed for two different cases; the first case is when DFIG is running at a speed lower than the synchronous speed and the second case is when DFIG is running at a speed above the synchronous speed. In both cases, the values of rotor voltage, stator current, rotor current, and the total generated power from the stator and rotor for DFIG are calculated from the analysis using MATLAB file (mfile) and compared with the practical results.
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