and solving becomes an immediate task. From this 2.3-MW inverter example, we may see that there are two main challenges: model design and customized model parameter estimation algorithm design. Challenge 1: IBR Model Structure Design In the past decade, a set of generic models for IBRs has been developed by the Western Electricity Coordinating Council's model validation subcommittee for grid dynamic P VPLL - P∗ + PI - id c ωL vb i∗ d + PI ud + - + vc d dqc va iq c ωL Q∗ - + Q θPLL (a) 40 20 -20 -40 100 200 -200 100 40 20 -20 -40 100 200 -200 100 Frequency (Hz) (c) figure 8. Two types of control structures differ in current controls: (a) dq-based current control and (b) stationary-framebased current control. Comparison of frequency responses and measurements: (c) dq-frame control and (d) stationaryframe control. 74 ieee power & energy magazine may/june 2022 102 102 200 -200 100 Frequency (Hz) 102 102 40 20 -20 -40 100 102 CGI Measurements dq-Frame Model 102 40 20 -20 -40 100 200 -200 100 102 Measurement Model 102 i∗ PI q + PI - uq + + vc q abc vc Phase (Degrees) Mag (dB) Phase (Degrees) Mag (dB) Phase (Degrees) Mag (dB) Phase (Degrees) Mag (dB)