The Electronic Realization of Synchronous Machines: Model Matching, Angle Tracking, and Energy Shaping Techniques

In this article, we investigate grid-forming and grid-following control strategies starting from a nonlinear state-space modeling viewpoint. An electronic synchronous machine is an inverter whose integral of the dc-bus measurement generates the angle of the instantaneous modulation vector. We show how this minimal augmentation constitutes an exact physical realization without requiring inner-current loops. The dc-link capacitance becomes the equivalent rotational inertia of the converter. Additional features, such as a phase locked loop, a voltage controller, and a power tracking mechanism are then designed via two energy-shaping techniques. One energy function is used to implement a grid-following control scheme, via the inherent synchronizing torque, while the other is used to implement a grid-forming control scheme. An alternative interpretation of active-power droop is suggested by this method. The results are first derived systematically, and then evaluated experimentally on a front-to-front setup.