H-infinity Robust Control of a Transparent Power-Hardware-in-the-Loop System

Power-Hardware-in-the-Loop system is a testing infrastructure capable of integrating real equipment and highly accurate real-time simulation models of power grids. The interface operating between the hardware and software is a complex hybrid control system tasked with ensuring that the both the hardware and simulation system are seamlessly integrated. As such, it may face stability, robustness and performance issues, for which different methods have been proposed in the literature. This paper proposes a novel method of designing the control interface using H-infinity robust control tools. We utilise a nominal model with parameter uncertainties, allowing the resulting controller to not only achieve robust stability within the uncertainty space but also improve performance and accuracy. Based on simulations containing a wide range of parameters, the H-infinity robust control method shows promising results compared with the state of the art in the literature. It offers the ability to synthesise a controller that is robust against uncertainties in time delay and impedance values, and at the same time, allows the designer to have more flexibility in characterising the performance and stability of the interface algorithm.