For the European Union (EU), the use of renewable energy resources has become the key to addressing environmental-related issues. Power electronic technology has been recognized as an effective solution to accommodate these increasing renewable resources in power grids. However, unlike the traditional synchronous generators (SGs), the dynamic behaviour of these converter-interfaced generators (CIGs) varies greatly with the actual control methods. The differences between CIGs and SGs can make the modelling, stability criterion, and control methods originally developed for traditional SG-dominated power grids no longer valid, which may prevent the integration of increasing renewable energy resources into the system. Moreover, the CIGs are essentially semiconductor-based switches without physical inertia. Under large disturbances, the CIG dynamics can become much faster than that of the SGs. How the fast dynamics of CIGs can affect power system stability is still unclear, which is investigated during this action.
To support the EU’s path to a sustainable economy, research into methods that assess and enhance the large-signal stability of low-inertia grids can have a great impact on the lives of many people and save society a lot of resources. The obtained academic achievements will become a milestone in addressing the low-inertia system security issues since it is the first time in the literature that the physical relationship between the nonlinear behaviour and the controlled dynamics of CIGs is established. In future research, the project results can be extended to several other relevant security issues of low-inertia grids. Furthermore, the project will also directly lead to the education of young researchers with relevant, unique research profiles within the area.
The main objective of this action is to assess and enhance the frequency security of a low-inertia power grid. Three issues have been studied during this action.
a) Dynamic modelling: Develop the model of a low-inertia power grid, including both the model of the CIGs and the electrical network, which can describe the dynamic behaviour of the system under large disturbances.
b) Stability assessment: Based on the developed model, investigate the transient stability and frequency stability of a power grid with CIGs.
c) Control design: Design control methods that can enhance the stability of the low-inertia power grid to accommodate the increasing renewable resources.
Other objectives including the FRESLING project management, training and career development, and the dissemination and communication of the research results have been also achieved through this action.
