With the recent changes in energy-production technology and with the extensive penetration of renewables into distribution networks, the power system models are again under close evaluation. In this project we study to what extent power electronics can replace rotating machines on a large scale and look into ways the energy transition could be performed seamlessly.

In three-phase networks, energy typically flows through several conversion stages, such as a magnetic air- gaps or switching devices, circulates in passive circuits and is bound to satisfy certain requirements. Objectives such as the transfer of power from DC to AC and the stabilization of the required harmonic motion, are increasingly addressed by voltage sourced converters (VSCs), due to their highly-flexible modulation capabilities. We study the behavior of VSCs and synchronous machines (SMs) from a control-theoretic perspective and observe a striking energy-conversion pattern. By augmenting an integrator for the DC-bus measurement, it is possible to create a feedback in such a way that the closed-loop dynamics of the VSC become structurally identical to those of the SM. With this minimal realization, the DC- voltage can be seen as angular velocity, while the electronic modulation synthesizes the geometric relationship between the rotor and stator windings. The resulting electronic synchronous machine provides a novel and unifying framework for synchronization, voltage regulation, power-flow control as well as frequency support for AC power networks. The latest developments have been submitted for publication and can be found in the ETH research collection.

Figure 1: The concept of electronic synchronous machine: a converter in closed-loop with the model-matching controller.

The people involved in this research project are Catalin Arghir and ESC member Prof. Florian Dörfler.

Prof. Florian Dörfler is a Professor at the Automatic Control Laboratory at ETH Zürich. The focus of the laboratory is research and teaching in the field of automatic control systems.

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