Grid-forming wind power plants
Doktorsavhandling, 2023

With growing concerns over climate change, the power system is witnessing an unprecedented growth in electricity generation from intermittent renewable energy sources (RES) such as wind and solar, which are commonly interfaced to the grid by power-electronic converters. However, increasing the penetration level of converter-interfaced generation units reduces the number of synchronous generators (SGs) in the grid that provide system services to support voltage and frequency, either inherently or through mandatory requirements and market products. This brings several challenges for the grid operators, which include increasing risk of harmonic interactions, decreasing system inertia and reduction in the short-circuit power of the grid, which all together might jeopardize the security and availability of the power systems. As a countermeasure, it is necessary that the power-electronic-based generation units not only provide grid support services that are originally provided by the SGs, but also operate in harmony with other generation units in all kinds of grid conditions. As a result, the concept of grid-forming (GFM) control, which mimics the beneficial properties of the SGs in converter systems, has emerged as a viable solution to allow effective and secured operation of power systems with increased penetration of converter-based resources.  

This thesis investigates the application of GFM control strategies in wind power plants (WPPs). In particular, the focus of the work will be on developing an effective GFM control strategy for the energy storage systems (ESS) in WPPs that not only supports the operation of the WPP in various grid conditions, but also offers a certain degree of GFM properties to the overall WPP. To start with, the selection of the most suitable GFM control strategy for wind power applications is made by evaluating and comparing various control strategies available in the literature. The comparison is based on their influence on the frequency characteristics of the converter and robustness of the controller in varying grid strength. To address the transient stability problem of GFM converters during current limitation, a novel strategy based on the limitation of converter's internal voltage vector is developed, which effectively limits the converter current to a desired value and retains the GFM properties of the converter at all times. An experimental setup is used to validate the effectiveness of the proposed limitation strategy in case of various grid disturbances. By implementing the proposed GFM control strategy for the ESS in a test WPP model, it is shown using detailed time-domain simulation results that the GFM behaviour can be offered to the overall WPP. The Network Frequency Perturbation (NFP) plots are used to verify the GFM behaviour of the considered WPP. Furthermore, an overview of various energy storage technologies (ESTs) suitable for providing ancillary services from WPPs is presented. With a focus on the two most suitable ESTs, i.e., batteries and supercapacitors, recommendations are given for design and sizing of the ESS for a given application. Finally, a coordinated control strategy between the WPP and SGs is developed, which facilitates the provision of frequency support from the WPP and at the same time reduces the energy storage requirements for the converter system.

wind power plants (WPPs)

grid-forming (GFM)


Ancillary services

frequency support


current limitation

energy storage systems (ESS)

transient stability

Room SB-M500, Sven Hultins Gata 6, Chalmers University of Technology, Gothenburg, Sweden
Opponent: Prof. Oriol Gomis-Bellmunt, UPC, Barcelona


Anant Narula

Chalmers, Elektroteknik, Elkraftteknik

Grid-forming (GFM) wind power plant (WPP) is a cutting-edge technology that seeks to transform the way renewable energy is harnessed. Unlike the more conventional WPPs, where the wind turbines (WTs) are designed to feed power into an existing electrical grid, GFM-WPPs are capable of creating their own grid by synchronizing the output of WTs with other energy sources, such as battery energy storage systems. This means that these power plants can operate independently, providing a reliable and stable source of energy even in the absence of a larger electrical grid. Furthermore, by mimicking the beneficial properties of the conventional synchronous generators, such WPPs are capable of providing grid supportive functionalities such as voltage and frequency regulation, which are the two key parameters influencing the stability of the power systems.

This thesis investigates the potential of energy storage systems (ESS) used in WPPs to offer the GFM capabilities to the overall WPP. For this purpose, an effective control strategy for ESS is developed, which not only provides a certain degree of the GFM capability to the WPP but also aids its operation during various grid conditions. This allows a higher penetration of wind power into power system as compared with what can be achieved with today's solutions, thereby supporting the transition to a more sustainable energy system.


Elektroteknik och elektronik



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5278



Room SB-M500, Sven Hultins Gata 6, Chalmers University of Technology, Gothenburg, Sweden

Opponent: Prof. Oriol Gomis-Bellmunt, UPC, Barcelona

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