Are there any standard benchmark power systems for harmonic power flow studies approved by organizations such as IEEE, IEC, etc or widely used by researchers to compare their methods?
The following benchmark for harmonic contribution is available but it doesn't do the job as it is very small and only for harmonic contribution studies.
I. Papič et al., "A Benchmark Test System to Evaluate Methods of Harmonic Contribution Determination," in IEEE Transactions on Power Delivery, vol. 34, no. 1, pp. 23-31, Feb. 2019, doi: 10.1109/TPWRD.2018.2817542.