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Study on Shunt Active Power Filter Control Strategies of Three-phase Grid-connected Photovoltaic Systems
摘要： This paper deals with the improvement of the energy quality using shunt active power filter. The three-phase grid-connected photovoltaic generator consists in solar panels, a three-phase voltage inverter connected to the grid and a nonlinear load constituted by a diode rectifier bridge supplying a resistive load in series with an inductor. In so doing, three main challenges arise from the application context. First, the harmonic currents and the reactive power must be compensated. The second challenge is the injection of active solar energy into the grid. Third, Maximum Power Point Tracking (MPPT) must be found. This paper proposes a method addressing those challenges. For the first and the second one, direct current and power controls is used. For the third challenge, an algorithm is proposed which take in account the electrical variables and the variation of the solar irradiation. Simulation results of the proposed method are shown. The method is illustrated with two different strategies: Hysteresis Control and Direct Power Control (DPC) for a variable load. Obtained results are presented and compared in this paper to confirm the robustness and the superiority of DPC strategy compared to Hysteresis Control strategy. In the same context, the simulation carried out in this article shows promising results with THD approximates 1.33 %.
关键词： photovoltaic system,MPPT,Direct Power Control,energy quality,Hysteresis Control
更新于2025-09-11 14:15:04
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Percentage depth dose fragmentation for investigating and assessing the photon beam dosimetry quality
摘要： Aim: The purpose of this study is to introduce a new approach to assess the dosimetry quality of photon beam with energy and irradiation field size. This approach is based on percentage depth dose (PDD) fragmentation for investigating the dosimetry quality. Materials and methods: For the investigation of the dosimetry quality of 6 and 18 MV photon beams, we have proceeded to fragment the PDD at different field sizes. This approach checks the overall PDD and is not restricted to the exponential decay regions, as per the International Atomic Energy Agency Technical Reports Series No 398 and the American Association of Physicist in Medicine Task Group 51 recommendations. Results and discussion: The 6 MV photon beam deposited more energy in the target volume than the 18 MV photon beam. The dose delivered by the 6 MV beam is greater by a factor of 1·5 than that delivered by the 18 MV beam in the build-up region and the dose delivered by the 6 MV beam is greater by a factor of 2·6 than that delivered by the 18 MV beam in the electronic equilibrium and the exponential decay regions. Conclusion: The dose measured at different points of the beam is higher for 6 MV than for 18 MV photon beam. Therefore, the 6 MV beam is more dosimetrically efficient than the 18 MV beam. Using the proposed approach, we can assess the dosimetry quality by taking into account overall PDD not only in the exponential decay region but also in the field.
关键词： radiotherapy efficiency,fragmentation,photon beam energy,quality index,dosimetry quality
更新于2025-09-10 09:29:36