In this document, a comparative survey for commonly used frequency estimators in VSC-based distributed generators is presented. The main objective is to determine the performance of such frequency estimations with several synthetic three-phase signals used as input. The tested estimators are implemented according to the original proposal and the study is focused on the analysis of the synchronous reference frame PLL (SRF), the flexible SRF PLL and the dual second-order generalized integrator frequency locked loop (DSOGI-FLL). When implemented in microgrids, the frequency estimator is responsible for the generation of a suitable reference for VSC controllers, specifically, for the Park transformation in the dq reference control. Also, this estimator returns the measured frequency at the point of common coupling, which is necessary for hierarchical controllers. As a result of this comparative analysis, a frequency estimator is chosen for simulation and analysis in a test microgrid with multiple VSC-based distributed generators.