Design of a modular and scalable small-signal dq impedance measurement unit for grid applications utilizing 10 kV SiC MOSFETs

Not only that tremendously increased employment of power electronics in the energy production, transfer, and consumption enables a sustainable future, it undoubtedly brings major energy savings and stimulating improvements in people´s quality of life. But not for “free”. This trend is considerably changing the nature of the sources and the loads in the electrical grid, altering their mild properties, and inflicting low-frequency dynamic interactions that did not exist in the conventional power system before. To be able to understand, analyze, design, and dynamically control the existing and future power systems, it is unarguably required to develop concepts and tools that offer better insights into the system-level behavior and stability of the grid. This paper presents the impedance measurement unit that can undoubtedly address some of the listed needs by characterizing in-situ source and load impedances of the sub-transmission medium-voltage networks (up to 69 kV). In addition to describing the design, this paper shows the experimental results obtained with the impedance measurement unit prototype built for 4.16 kV, capable of characterizing medium-voltage distribution systems of up to 2.2 MVA.