Study of grid interactions of Voltage Source Converters controlled as a Virtual Synchronous Machine

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The goals of this PhD proposal can be summarised as:1) Nowadays, there is not a standard definition of a VSM converter control requirements and more than 15 possible implementations can be found in the literature [5]. The first goal of this thesis is to identify the VSM/grid forming characteristics more interesting for wind power applications and select the most appropriated implementation.2) VSM pretends to mimic certain characteristics of a synchronous machine in a power converter but both types of equipment have very different physical and dynamic characteristics. The second goal of this thesis is to understand the converter hardware restrictions (current limit, required energy storage for inertia emulation...) and the software restrictions, answering what are the maximum/minimum gains that guarantee the desired VSM/grid forming dynamics. 3) The third goal is to study the VSM dynamics and performance in relation to a) delivery and provision of designed-in properties, b) internal stability between the electrically closely coupled VSM controllers, c) stability and dynamic interaction between the wind farm and the remaining power system. The study should investigate the influence of the characteristics of the export line and the connection conditions, such as length and type of export line and strength of connection point, on before mentioned properties of VSM dynamics and performance.