Small-Signal Stability Assessment of Controller Hardware-In-Loop EMT Simulations

Power system controllers are typically designed using continuous time realizations and are then implemented in a digital platform using discrete equations. The performance of the controller is then evaluated with Hardware-in-loop EMT simulation in which the controller is interfaced with a real-time simulation model of the power network. In order to assess the performance of this simulation setup, the paper investigates how the time-step selection and interfacing delays of the digital controller implementation affect the dynamic behaviour of the overall simulation. The paper formulates an analytical approach using the well-known lifting technique, from which a shift-invariant model is derived for the overall system. An eigenvalue based small-signal stability assessment and parametric sensitivity analysis is conducted with the resulting model which is further validated through time-domain EMT simulations.