News from AAU Energy

AIM-toolbox developed by energy researchers licensed to both industry and academia

AIM-toolbox developed by energy researchers licensed to both industry and academia

The Automated Impedance Measurement (AIM)-toolbox is the world’s first impedance measurement software that is used in several commercial projects of High-Voltage Direct-Current (HVDC) transmission systems. The AIM-toolbox enables to automatically measure impedance profiles of power electronic systems across a wide frequency range. The measured impedances can be used to screen the risks of sub-synchronous resonances and harmonic instabilities in power-electronic-based power systems (PEPS), e.g., wind farms, photovoltaic (PV) power plants, multi-terminal HVDC (MTDC) systems, and energy islands, etc.

Professor Xiongfei Wang and Assistant Professor Heng Wu, and other eGRID group members have been persistently in developing methods and tools for screening stability risks in power-electronic-based power systems (PEPS). After years of efforts, they have developed rigorous theories and methods for the AIM-toolbox.


Power outages due to system interactions of power converters are increasingly reported across the globe, raising significant concerns from system operators. Therefore, prescreening stability risks are mandatory for system operators to permit new grid connections of power converters.

- To tackle the challenge, the AIM-toolbox is developed to map the small-signal dynamics of PEPS into frequency domain, and thus a computationally-efficient stability analysis can be performed by using frequency-domain analysis tools. Further, with the rigorous theoretical basis laid by eGRID researchers, the AIM-toolbox ensures accurate impedance measurement and reliable stability prediction, says Professor Xiongfei Wang.

The AIM-toolbox has been commercially licensed to two European Transmission System Operators (TSOs), i.e., Energinet (Danish TSO) and TenneT GmbH (German TSO). Together with TenneT GmbH, the AIM-toolbox has also been further developed for stability analysis of multi-vendor MTDC power systems. Besides the industry applications, the AIM-toolbox has also been licensed to Yonsei University, South Korea, for research and education purposes. 

For more information please visit the eGRID research webpage


Research group leader and Professor Xiongfei Wang, AAU Energy, mobile: +45 2136 9166, e-mail:

Assistant Professor Heng Wu, AAU Energy, mobile: +45 9356 2219, e-mail: