In this paper a harmonic power flow formulation for microgrids based on a power flow linearized through Wirtinger's calculus is presented. Through this formulation it is possible to calculate the harmonic power flow independently of the fundamental power flow, which is an advantage when working with tertiary control problems in microgrids. The algorithm with which the formulation was simulated is presented. The fundamental and the harmonic power flow are implemented in a modified CIGRE test case for microgrids. Finally, an evaluation of the harmonic distortion associated to the PV systems modeled is exposed, and performance evaluation is also presented by comparing the presented approach with the currents injection harmonic power flow method starting from an iterative power flow.