Harmonics and interharmonics compensation with active front-end converters based only on local voltage measurements

The current grid codes for distribution networks impose on operators to provide ancillary services, like fault ride through capability and reactive power compensation. In this context, generating units with power electronics interfaces could offer as an additional service the active compensation for harmonic and interharmonic currents introduced by other converters or distorting loads. Typically, the converters of these generating units do not have information on the distortion of either other loads or of the grid current. Thus, this paper presents a control algorithm for grid harmonics and interharmonics compensation that relies only on the measurement of the voltage at the point of connection of the unit. The reference for the compensating current is calculated from the harmonic components of grid voltage in the synchronous reference frame. The paper also addresses the influence on the compensation performance of the line impedance between the generating unit and the point of connection. Experimental tests on a laboratory setup fully validate the proposed compensation method.