The Complete Production Process of Winded Soft-Pack Lithium-ion Batteries

 

This article details the complete production process of wound soft-pack lithium-ion batteries, from positive and negative electrode material coating, winding, tab welding, calendering and slitting, assembly and testing.

[Expert Report] Ding Lei, Shandong University: A Re-understanding of Power System Inertia

 

ELETRÔNICA DE POTÊNCIA-Retificador meia onda controlado a tiristor (RL)

 

Power Electronics in Renewable Energy Systems Suntio, Teuvo; Messo, Tuomas

 

ABSTRACT .The observed changes in weather conditions have accelerated the installation of renewable energy-based electricity systems around the world. Large-scale utilization of renewable energy sources in electricity production requires the use of power electronic converters to integrate the renewable energy systems into the power grids. This integration brings about certain challenges in terms of stability and robust performance of the power grids, which have to be solved before the wellbeing of the power grids can be guaranteed. This Special Issue of Energies aims to reveal the state-of-art in addressing interfacing problematics. According to the published papers, clear advancements have taken place, but the most critical issues remain unsolved. Direct power control with self-synchronizing synchronverters may be the most promising technique for solving the main stability problem, although many unsolved problems still persist. Another challenge in renewable energy production is the fluctuating nature of the available energy in renewable energy sources, which require utilization of stored energy to smooth the fluctuations. Different storage battery technologies are available, but their production may pose problems in the long term.

 ORIGINAL LINK:https://trepo.tuni.fi/handle/10024/225285

Dynamic Characteristics of Grid-Connected Three-Phase Z-Source Inverter in Photovoltaic Applications-Tampere University of Technology-Author Juha Jokipii

 Juha Jokipii Dynamic

 Characteristics of Grid-Connected Three-Phase Z-Source Inverter in Photovoltaic Applications

 Thesis for the degree of Doctor of Science in Technology to be presented with due permission for public examination and criticism in Festia Building, Auditorium Pieni Sali 1, at Tampere University of Technology, on the 15th of April 2016, at 12 noon.

ABSTRACT

 Due to the inevitable depletion of fossil fuels and increased awareness of their harmful environmental effects, the world energy sector has been moving towards extensive use of renewable energy resources, such as solar energy. In solar photovoltaic power generation, the needed interface between the source of electrical energy, i.e., a photovoltaic generator, and electrical energy transmission and distribution systems is provided by power electronic converters known as inverters. One of the latest addition into the large group of inverter topologies is a Z-source inverter (ZSI), whose suitability for different applications have been extensively studied since its introduction in 2002. This thesis addresses the dynamic characteristics of a three-phase grid-connected Z-source inverter when applied to interfacing of photovoltaic generators. Photovoltaic generators have been shown to affect the behavior of the interfacing power converters but these issues have not been studied in detail thus far in case of ZSI.

In this thesis, a consistent method for modeling a three-phase grid-connected photovoltaic ZSI was developed by deriving an accurate small-signal model, which was verified by simulations and experimental measurements by means of a small-scale laboratory prototype inverter. According to the results presented in this thesis, the small-signal characteristics of a photovoltaic generator-fed and a conventional voltage-fed ZSI differs from each other.

The derived small-signal model was used to develop deterministic procedure to design the control system of the inverter. It is concluded that a feedback loop that adjusts the shootthrough duty cycle should be used to regulate the input voltage of the inverter. Under input voltage control, there is no tradeoff in between the parameters of the impedance network and impedance network capacitor voltage control bandwidth. Also the small mismatch in the impedance network parameters do not compromise the performance of the inverter. These phenomena will remain hidden if the effect of the photovoltaic generator is not taken into account. In addition, the dynamic properties of the ZSI-based PV inverter was compared to single and two-stage VSI-based inverters. It is shown that the output impedance of ZSI-based inverter is similar to VSI-based inverter if the input voltage control is designed according to method presented in the thesis. In addition, it is shown that the settling time of the system, which determines the maximum power point tracking performance, is similar to two-stage VSI-based inverter.

The control of the ZSI-based PV inverter is more complicated than the control of the VSIbased inverter. However, with the model presented in this thesis, it is possible to guarantee that the performance of the inverter resembles the behavior of the two-stage VSI, i.e. the use of ZSI in interfacing of photovoltaic generators is not limited by its dynamic properties.

THESIS LINK : https://trepo.tuni.fi/handle/10024/213108