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

该博士提案的目标可以总结为：1)目前，没有VSM转换器控制要求的标准定义，在文献[5]中可以找到超过15种可能的实现。本文的第一个目标是确定风电应用中更有趣的VSM/网格形成特征，并选择最合适的实现。2) VSM假装模拟电源转换器中同步机的某些特性，但两种类型的设备具有非常不同的物理和动态特性。本文的第二个目标是了解转换器的硬件限制（电流限制，惯性仿真所需的能量存储……）和软件限制，回答保证所需VSM/网格形成动力学的最大/最小增益是什么。3)第三个目标是研究VSM的动力学和性能，涉及a)交付和提供设计特性，b)电紧密耦合VSM控制器之间的内部稳定性，c)风电场与剩余电力系统之间的稳定性和动态相互作用。研究应考察出口管线的特性及连接条件，如出口管线的长度、类型、连接点的强度等对上述VSM动态性能的影响。

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.