Paper addresses performances of recursive technique, extended Kalman filter, for voltage dips and interruption detection. Performance of this method is tested in microgrid with high level of distributed generation, and compared with RMS, FFT and Kalman filter. Kalman filter and extended Kalman filter are applied with basically different approach. Modeling and testing are carried out in the MATLAB/SimPowerSystems environment. Modified IEEE13 bus system with high level of distributed generation is used. Methods are also applied in real-time laboratory system, as part of grid-tie inverter control, and based on measured computation complexity and ease-of-use conclusions about cost of implementation are derived.