Improved power hardware-in-the-loop interface algorithm using wideband system identification

Power hardware-in-the-loop (PHIL) simulation techniques are being increasingly applied in the power system field for novel equipment testing and validation. To ensure the accuracy and stability of the overall simulation, special care must be taken in the control of the virtual power interface between the hardware under test and software simulated system. The application of wideband system identification techniques to the Damping Impedance Method (DIM) interface algorithm is investigated in this paper. Knowledge of the hardware under test impedance over a wide frequency range improves the simulation accuracy and ensures interface stability under dynamic and transient conditions. A small-signal, white noise perturbation is injected into the hardware under test using the switching converter acting as the power interface between software and hardware. Cross correlation methods are then used to construct a wideband estimation of the hardware impedance. This information is used to update the interface algorithm and guarantee simulation accuracy and stability. Simulation results are provided for two PHIL test scenarios, demonstrating the improvements afforded by the augmented DIM interface. In each case, initial mismatch between a model of the hardware under test and the actual component degrades the performance and stability of the PHIL interface. Employment of the proposed identification technique to update the interface controller mitigates stability issues and improves the simulation accuracy.