Passive Method for Estimating Fundamental Frequency Grid Impedance: Including Model and Field Verification

This letter presents a field-verified passive method to estimate the equivalent fundamental frequency grid impedance. The method requires reactive power, active power, and root-mean-square voltage measurements as inputs and is based on a mathematical derivation independent of the angle and frequency estimation. A thorough verification process was adopted, comprising simulations in EMT utilizing a wind turbine with actual control code, field wind turbine measurements, and an operational wind power plant where the transmission system operator agreed to change grid configurations to allow testing of the algorithm for two grid scenarios. Results show good agreement between expectations and estimation from the proposed method.