dSPACE Implementation for Real-Time Stability Analysis of Three-Phase Grid-Connected Systems Applying MLBS Injection

Renewable resources such as solar and wind are most commonly connected to a utility grid through inverters. The stability and system characteristics of such systems can be defined by the ratio of grid impedance to the inverter output impedance. Since the impedances vary over time with numerous operation conditions, real-time measurements are required to verify the stability. The impedance measurement technique based on maximumlength-binary-sequence (MLBS) injection and Fourier techniques has been proven to be an efficient option for online analysis of grid-connected systems. This paper shows how a hardware-in-the-loop simulation based on dSPACE can be implemented for stability analysis of a grid-connected inverter using the MLBS injection. The method makes it possible to modify the inverter control characteristics and grid conditions online, thereby providing means for various stability and control design studies for grid-connected systems. We have presented a measurement example based on a three-phase grid-connected inverter and used this example to demonstrate the implementation.