Harmonic interaction between large numbers of photovoltaic inverters and the distribution network

The dominating mechanisms of interaction between large populations of PV inverters and the electrical distribution network are investigated. Some demonstration projects with large number of small PV-inverters in a low voltage network, show high levels of voltage distortion, although the emission level of an individual PV inverter satisfy the PQ standards. The main object of this paper is to analyse the observed phenomena of harmonic interference of large populations of inverters and provide some explanation of the resonance between existing network components and the PV inverters. These resonances may lie typically between the 5th and 40th harmonic number. The resonance phenomenon is investigated using extensive laboratory experiments on two inverter topologies, as well as computer modelling of different inverter topologies and network simulation studies on the Vroonermeer-Zuid network.