Investigation of the impact of PV generators on harmonic resonances in medium voltage power distribution systems

Abstract

Modern electric power distribution systems have migrated from a passive, non-supervised structure with a low level of automation to an active and supervised structure, with a high level of automation due to the introduction of photovoltaic generators, smart meters, and new automatic control and reactive power compensation devices. In the case of photovoltaic generation, for example, the world installed capacity reached around 1 TW and, in Brazil, there are more than 1,600,000 units in operation, achieving more than 16 GW installed. In terms of new reactive power compensation equipment, some devices are currently commercially available employing series capacitors for medium voltage networks and shunt capacitors for low voltage networks. Despite the technical and environmental advantages of this change, with the introduction of these emerging technologies, new challenges and technical issues may arise. As several of these technologies employ electronic converters with a network interface, not only there is a possibility of harmonic current injections, but there is also a risk of poorly damped or unstable harmonic resonances due to the interaction with the reactive power compensation elements. In this context, the objective of this project is to investigate the risk of harmonic resonances in medium voltage distribution systems in the presence of photovoltaic generation and modern reactive power compensators such as shunt capacitor banks via computer simulation. To properly conduct this investigation, a simplified photovoltaic generator model will be used for analysis in the frequency domain. Computer simulations will be employed to produce operational data of the system so that harmonic power flow can be run to analyze the problem. Then, a real Brazilian distribution system will be employed to evaluate the harmonic distortions and the occurrence of resonance and how it impacts the power quality indicators. (AU)