Control of inverter-based distributed generation in low-inertia power systems

在减少温室气体排放、改善空气质量和应对气候变化的需要的推动下，可再生能源进入电网的普及率多年来一直在上升。与传统的同步发电机不同，大多数可再生能源通过电力转换器接入电网。控制策略的设计允许它们并入电网，并使它们适应传统同步发电机众所周知的和公认的控制和稳定规则。由于功率转换器的类型不同，其灵活性和制造商数量众多，为每个功率转换器设计的控制器可能会非常不同。尽管通过使变流器适应同步电机的规则来整合变流器到目前为止在维持系统稳定性方面是有效的，但随着可再生发电所占比例的增加，可能会威胁到电网的稳定和供电安全。此外，由于可再生能源的普及率预计将继续增加，这可能导致电力系统几乎没有同步发电机，甚至没有同步发电机。本课题将对电力系统的稳定性进行研究，并试图为以电力电子为主/仅含电力电子设备的电网中的功率变流器寻找新的控制设计准则。因此，该项目在能源主题下与EPSRC的能源网络研究领域保持一致。这项工作将从回顾以前对功率转换器控制器进行的稳定性分析开始。然后，用不同的控制策略对通过功率转换器提供不同比例功率的稍微简化的电力网络进行仿真。对采用不同控制策略时功率变流器之间的相互作用进行了解析研究。通过仿真和理论分析，列举了一些控制设计规则，如果应用于所有功率变流器，则可以提高系统的整体稳定性。为了验证仿真结果，可以采用功率-硬件在环的方式构建一个小型化的实验样机。

Driven by the need to reduce greenhouse gas emissions, improve air quality and address climate change, the penetration of renewables into the electrical network has risen over the years. Unlike traditional synchronous generators, most renewables are connected to the power network through power converters. Control strategies have been designed to allow their integration into the network and adapt them to the well-known and well-established control and stability rules of the traditional synchronous generators. Due to the different types of power converters, their flexibility and the high number of manufacturers, the controllers designed for each power converter can be very different to each other. Although integration of converters by adapting them to the rules of the synchronous machines has been effective so far in maintaining the stability of the system, renewable generation could threaten the network stability and security of supply as its proportion increases. Besides, since the penetration of renewables is expected to keep increasing, it could lead to a power system with few or even no synchronous generators. This project will study the stability and will attempt to find new control design rules for power converters in electrical networks with power electronics mainly/only. The project is, therefore, aligned with EPSRC's Energy Networks research area within the Energy theme.The work will begin by reviewing previous stability analyses conducted on power converter controllers. Then, a somewhat simplified electrical network with different proportions of power provided through power converters will be simulated with various control strategies. The interaction of power converters with each other when controlled with different strategies will be analytically studied. From the simulations and theoretical analyses, some control design rules will be enumerated that could improve the overall stability if applied to all power converters. A down-scaled experimental prototype converter could be built in a power-hardware-in-the-loop arrangement to verify simulation results.