Field–Circuit Cosimulation of 500-kV Transformers in AC/DC Hybrid Power Grid

To achieve the communication between field and circuit network solvers in an actual large-scale AC/DC hybrid power grid, a cosimulation system of electromagnetic transient calculation, on-site measured data, and finite-element simulation has been developed. A platform based on MATLAB is adopted for linking measured data, electromagnetic transient simulation in real-time I/O, and combining finite-element software offline. A dc bias on 500-kV transformer is analyzed with the cosimulation approach. Hypersim and Flux are used as electromagnetic transient and finite-element simulation software, respectively. A specific on-site measuring system is developed to obtain the dc bias current. With the platform, dc bias of 500-kV transformers is finally solved. The validity of the model is verified by no-load field testing in 100% and 110% rated voltage.