Since the penetration of photovoltaic (PV) systems in the low voltage (LV) distribution network is increasing, the need to register and model the contribution of these systems to the harmonic distortion of current and voltage waveforms is becoming an up-to-date issue. As PV systems incorporate power conditioning units, which are harmonic generating devices, they will have an influence on quality of supply, reliable operation of system equipment as well as component life expectancy. This paper investigates the harmonic impact of a 20 kWp PV system connected to the LV distribution network in Greece. The harmonic behavior of the PV plant as a function of the solar radiation under several weather conditions is analyzed. Measurements results are compared to those obtained from the power simulator package PSIM^copy. The level of penetration of PV systems in the LV distribution network without harmonic limits been exceeded is investigated.

Research on smart grid technologies has been advancing over the last years, producing novel practices concerning mainly the power distribution networks. However, in many countries these networks still operate in their traditional form, without offering the real-time operational characteristics which are essential for the utilization of the aforementioned practices. On the other hand, due to the extent of urban power distribution networks, as well as the substantial cost of medium voltage equipment, the full upgrade of these networks is in most cases not a feasible option. In this work, alternative options of selective automation upgrade in power distribution networks are offered, corresponding to the desired operational status of these networks. More specifically, the essential upgrades are analyzed for the implementation of reliability improvement and loss reduction techniques on such a network.

Integration of distributed generation (DG) in existing distribution networks has been studied thoroughly during the past years as a measure of reducing grid's power losses. However, the optimal DG placement, known as ODGP, toward loss minimisation, has not been studied in depth by considering the possible impact of the reverse power flow (RPF) caused by extended penetration of distributed energy resources. This study uses a constriction factor embedded local particle swarm optimisation algorithm along with the appropriate particle formulation that solves the ODGP problem by taking into account the impact of possible RPF. In this study, the idea of RPF modelling is introduced by providing extended versions of IEEE test systems. Modified versions of the IEEE 30‐bus and IEEE 33‐bus test systems are modelled and results are presented in order to highlight the impact of RPF on the ODGP problem solution. The mathematical formulation is given, results and analysis for both extended systems are presented, while the importance of RPF for different conditions is assessed.