Generic EMT modeling method of Type-4 wind turbine generators based on detailed FRT studies

Developing effective electromagnetic transient (EMT) models of wind turbine generators (WTGs) is essential for power system transient analysis. However, manufacturer-specific EMT models are usually available as black boxes, which is not easy to be used in practical applications. To address this issue, a four-step generic EMT modeling method is proposed for type-4 WTGs based on detailed fault ride-through (FRT) studies. Step one, massive FRT field tests are conducted on type-4 WTGs, and generic FRT responses of active and reactive power are extracted and parameterized to characterize a wide variety of controller strategies of various vendors; Step two, piecewise expressions of active and reactive power responses are derived to formulate the detailed FRT processes, including the FRT control process during a fault, post-fault recovery control process, and their switching transients; Step three, a generic controller, to emulate the FRT responses, is implemented in the WTG model by automatically updating current references utilizing the derived analytical formulation; Step four, a stepwise identification method is proposed to identify the FRT control parameters, proportional-integral controller parameters, and circuit parameters. The proposed modeling method is verified by field tests, and the results show that the developed model can accurately capture the FRT behaviors of practical type-4 WTGs.