Harmonic Mitigation in Low-Voltage Distribution Networks: Sensitivity Analysis

The increased penetration of converter-interfaced distributed renewable energy sources (CI-DRES) along with the existence of non-linear loads (NLLs) might cause severe power quality problems in distribution networks (DNs). Currently, various methods have been proposed so that voltage source converters (VSCs) of the CI-DRES act also as harmonic filters, however, most of them mitigate the problem locally without examining which CI-DRES within the DN would be most suitable to provide such service. In this paper the mathematical framework and a sensitivity analysis is performed in order to evaluate the contribution of each CI-DRES in the decentralized harmonic filtering process, with the presence of NLLs within a low-voltage (LV) DN based on the CI-DRES location and available capacity. The available capacity is an important parameter, since in the future, the CI-DRES might provide simultaneously several services, e.g. reactive power or virtual inertia. The mathematical framework for the quantification of the CI-DRES contribution is validated via simulations in the time domain and via harmonic power flows in the benchmark CIGRE LV network under various mixtures of CI-DRES/NLLs. The derived conclusions will pave the path, so that the active filtering can be treated as a new ancillary service to be provided by CI-DRES and introduced in respective markets.