The electromagnetic transient (EMT) simulation is an essential tool for studying power grids dominated by inverter-based resources (IBRs). However, due to small simulation time steps and increasing problem sizes , performing EMT simulations for large-scale power grids becomes computational-intensive, and often impractical. To address this challenge, we developed ParaEMT, an open-source Python-based EMT simulator that is parallelizable and compatible with high-performance computing (HPC) systems for simulating large-scale power grids with a significant presence of IBRs. Its key features include: 1) utilizing parallel computation for network solution by decomposing the network conductance matrix into the bordered block diagonal form; 2) enabling parallel updates of device states and network historical currents; 3) leveraging HPC to further accelerate simulation through a developed generic interface. The accuracy of ParaEMT has been validated on the reduced 240-bus (720-node) Western Electricity Coordinating Council system by benchmarking the EMT dynamics against PSCAD. Furthermore, ParaEMT achieves a notable speedup of approximately 25 to 36 times on a synthetic 10,080-bus (30240-node) system by leveraging the HPC resource named Eagle at the National Renewable Energy Laboratory. A regional 100% renewable case of the reduced 240-bus system has been developed for simulating system-wide IBRs’ interactions in large-scale power grids using ParaEMT.

The traditional measurement methods of capacitance parameters of coupled transmission lines bring large measurement errors under a strong electromagnetic-interference environment. To solve this problem, new anti-interference measurement methods based on harmonic components are proposed. First, the voltages and currents at the head end and the tail end of the transmission line are sampled synchronously based on global positioning system (GPS) technology, then they acquire the third harmonic components from the measured data with an interpolation fast Fourier transform algorithm, and substitute them to the calculation formulae, so that the power frequency interference signals are filtered as noise and the capacitance parameters can be accurately measured. The wiring diagram of line parameter measurement and the hardware structure of the measuring system based on GPS are given. The simulation results with PSCAD and an example of measuring two 200-kV coupled transmission lines are given. The comparison of measurement results between the proposed methods and the traditional methods is also shown.

Based on transmission-line equations and the distributed parameter model, a new approach is proposed to accurately measure the zero-sequence parameters of long-distance double-circuit transmission lines using voltages and currents measured at the ends of lines. The mathematical model of the proposed method is explained in detail, and the differential equations of two coupled lines with different self parameters were solved for the first time with Laplace transform to obtain all of the zero-sequence parameters. And this approach is easy to implement since the measurement process is simple. PSCAD simulation experimental results of double-circuit 500 kV transmission lines with line lengths changing from 200 to 1000 km and a comparison of the measurement results between the proposed method and the traditional method are shown. Simulation experiments validate that whether the two lines are short or long, the new approach has high accuracy even if there is system white noise and interference from other coupled lines.