Digital Real-Time Power System Co-simulation via Distributed Transmission Line Model

The intrinsic complexity of smart grids requires computer-aided power system analysis to evaluate novel monitoring and control strategies and innovative devices. Due to the enormous computational requirements and the necessary Hardware-In-the-Loop (HIL) and Power Hardware-In-the-Loop (PHIL) applications, real-time power system simulation plays a fundamental role in this context. However, performing real-time simulations in a monolithic way, i.e. exploiting a single Digital Real-Time Simulator (DRTS) rack, could result in the inability to create reliable and accurate digital twins of increasingly complex power systems such as smart grids. This paper proposes a digital real-time power system co-simulation to link different DRTS and scale up the viable Power System Under Test (PSUT). It exploits Aurora 8B/10B to manage the data exchange and a Distributed Transmission Line Model (DTLM) to split the PSUT into the two real-time simulation environments. Furthermore, the DTLM permits the absorption of the communication latency, which normally occurs in real-time co-simulation, into the propagation model of a transmission line. With the presented setup, a time step duration of $50 \mu \mathrm{s}$ proves to be stable and accurate when running a co-simulated Electro-Magnetic Transients (EMT) analysis of a power grid scenario by interconnecting two commercial DRTS (i.e. OPAL-RT) with comparable results compared to the monolithic simulation, extending the scalability of future real-time smart grid simulations.