FRESLIPS (SEAI RD&D Funding Programme)

This proposal is about the definition of feasible and practical solutions for the frequency control and stability analysis of power systems with high penetration of renewable energy sources and low inertia. These solutions are based on a novel theoretical approach recently developed by the lead applicant that is aimed at defining the fundamental relationship between power and frequency variations in AC systems.

The proposed theory addresses several important challenges of modern power systems. It exploits the heterogeneous variety and high granularity of distributed, renewable energy resources based on power electronics, the ubiquity of broadband communication networks and the unprecedented availability of large amounts of measurement data that characterise the smart grid.

The contributions of the project are the following.

  • To provide the foundations of the proposed theory, including the reformulation of the models of power system devices in terms of the proposed theoretical framework.
  • To apply the proposed theory to design effective controllers.
  • To define a novel framework for the stability analysis of the smart grid.
  • To propose practical applications of the proposed theory, namely dynamic state estimation and an unconventional technique to estimate local frequency variations.

All contributions above will be duly validated through real-world measurements, hardware-based tests and field trials.

The expected results of the project are a set of practical solutions that practitioners can implement in the field. The proposed theory is thus a timely and useful tool to foster the development of flexible, efficient, secure and sustainable power systems and smart grids.

Three PhD students and one PostDoc will be funded through this project. The topics of the PhDs are the following:

  • PhD 1. Modelling This PhD will focus on the theoretical foundations of this project. The starting point is the derivation of the analytical expressions the FDF/RoCoP and us e it to develop the relationship between active and reactive power rates of change and frequency for most relevant devices, including grid-forming and grid-following converter-based generation and large energy storage systems, virtual power plants, HVDC transmission lines, microgrids, energy communities and charging stations of electric vehicles. Stochastic processes, nonlinearity and other idiosyncrasies of the models, in particular those related to renewable energy resources, will be duly taken into account.
  • PhD 2. Control and Stability Analysis This PhD will focus on the design of frequency control and stability analysis of power systems. The objective is to design controllers to improve the dynamic response, the stability and the resilience of power systems. The scenarios of transmission systems with low-inertia and high shares of renewable energy sources as well as of distribution systems with high-granularity resources will be thoroughly investigated. Since the evaluation of involves measurements of the frequency at remote buses and the communication of such measurements, the effect of latency and noise and other features of the control systems will be duly taken into account. The work package will also focus on the stability analysis of low inertia power systems. First the conventional concepts of angle, voltage and frequency stability of power systems will be thoroughly revisited in terms of the proposed theory. Then the new stability issues related to power electronic converters and microgrids will be considered.
  • PhD 3. Dynamic State Estimation This work package will elaborate on the preliminary results obtained by the LA on dynamic state estimation to evaluate the equivalent inertia and fast frequency control provision of converter-interfaced generation, and extend this analysis to the estimation of other relevant quantities, such as the equivalent droop coefficients of aggregated models of distribution systems with high shares of distributed generation, flexible loads, microgrids and energy storage devices. This work package will also focus on the estimation of local frequency variations of AC quantities using the concept of “local time”. This will be utilised to design and file a patent on the design of a novel “frequency measurement unit” that will compete with existing PLLs and PMUs implementations.

Publications related to the project are available here and here.

More details on the software tool developed for the project is available here.