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Speaker: Eitan Brown,
M.Sc. student under the supervision of Prof. George Weiss
Wednesday, October 28, 2015 at 15:00
Room 011, Kitot Bldg., Faculty of Engineering
A study of the use of synchronverters for grid stabilization using simulations in SimPower
Abstract
Synchronous generators (SG) have the following useful property: once synchronized, they stay synchronized even without any control, unless strong disturbances destroy the synchronism. This is one of the features that have enabled the development of the AC electricity grid at the end of the XIXth century. Today, the stability of networks of synchronous generators that are coupled with various types of loads and other types of power sources (such as renewables) and are operated with the help of multiple control loops, is an area of high interest and intense research.
This is partly due to the proliferation of power sources that are not synchronous generators, which threatens the stability of the power grid. These power sources use inverters to deliver power to the grid. Most inverters are designed to deliver maximum power from the source and they do not contribute to grid stability, quite the contrary: they introduce disturbances due to the intermittent nature of the power source and they increase the sensitivity of the grid to other disturbances such as faults.
An inverter which behaves like a synchronous generator can simplify the modelling of the overall system and the overall system behavior during sudden disturbances or faults will be as stable as it would be without the inverter or even better. Such inverters, sometimes called synchronverters, have been proposed in several papers, I will refer in this work to the paper of Qing-Chang Zhong and George Weiss (2011) Inverters that mimic synchronous generators, IEEE Trans. Industrial Electronics, vol. 58, pp. 1259-1267. The grid operator can relate to synchronverters in the same way as to classical generators, which makes the transition to the massive penetration of renewable and other distributed energy sources easier and smoother.
I will present some known problems and solutions regarding power grids and demonstrate how synchronverters help the grid to recover from faults and reduce unwanted oscillations better than popular known solutions. The end of my thesis will discuss an additional practical use of the synchronverter for energy storage units.
and the 
-directions. A number of tests were carried out under displacement control with four different displacement ratios 
, where 
and 
are, respectively, the minimum and maximum machine displacements in a cycle; the ratios included 
= 0.1, 0.33, 0.5 and 0.75. Each displacement ratio 
corresponds to a different load ratio 
where 
and 
are, respectively, the minimum and maximum load in a cycle. The data collected during the tests was used to determine the delamination propagation rate da/dN as a function of the nearly mode I energy release rate 
.
was found. Then, the correlation was used in order to approximate the delamination length in each cycle of the fatigue test.
was used, all of the data obtained for the different displacement ratios nearly collapsed into one master curve. The experimental data was then back calculated from the master curve, enabling a reliable prediction of the delamination propagation rate da/dN for any given load ratio for this type of material and layup.
