Improved Accuracy, Modeling, and Stability Analysis of Power-Hardware-in-Loop Simulation With Open-Loop Inverter as Power Amplifier

The accuracy of a power-hardware-in-loop (PHIL) simulation is influenced by factors such as dynamics of the power amplifier (PA) and discretization of the real-time simulated part of the system. An open-loop voltage-source inverter (VSI) without an output filter is demonstrated to be a good choice for power amplification in terms of cost, size, design effort, bandwidth, and accuracy when the load on the PA is significantly inductive. An open-loop-VSI-based PA is shown to be accurate in emulating a synchronous generator, including the fast transients in the excitation control system. The discretization effects of the real-time simulator are captured effectively by the discrete-time (DT) modeling approach proposed in this paper. The DT model is shown to replicate fast transients in the PHIL simulation better than the existing continuous-time-based model. Stability of the PHIL simulation of a benchmark circuit is analyzed using the proposed DT modeling approach. The stability analysis is validated through simulations and experiments. The stability limits derived based on the proposed analysis are capable of suggesting maximum and minimum values of certain circuit parameters, as required for stability.