Expansion of the residential photovoltaic systems and its harmonic impact on the distribution grid

As photovoltaic systems incorporate power converters, which are harmonic generating devices, they will have an influence on power quality of supply network. This paper investigates the impact of the first 10kW residential photovoltaic (PV) system connected to the low-voltage distribution network in Croatia. The harmonic impact of such a PV plant is measured in two periods: winter and summer. Analysis of the recorded data is done regarding harmonic content of the PV current. Based on the measured data, a computer model of the plant and local distribution network is made. The model is used to simulate several scenarios of residential PV plant expansion. In the first scenario it is assumed that one third of the households that are connected to the local grid will install 10kW PV plants. The second scenario assumes that all the households will install 10kW PV plants. However, the PV plants are not the only harmonic sources in a distribution grid. The grid usually supplies many nonlinear loads, which absorb distorted current. To consider that influence, another harmonic current source is modeled. Mutual influence of PV and grid harmonics is also analyzed. The results of the simulations and conclusions are given at the end of the paper.