PV Plant Connection in Urban and Rural LV Grid: Comparison of Voltage Quality Results

Renewable energy sources (RES) today are basic part of power system. Their penetration is present on each voltage level, from high voltage (HV) to low voltage (LV) level. Each analysis of power system regarding power grid analysis must take in account presence of RES or planned penetration of RES. RES have various impact on power grid where they are connected, in terms of load flow analysis, protection schemes, power quality and others. That impact can be positive, but negative as well. Each case of connecting RES on power grid must be analysed separately. Regarding power quality, impact of RES on point of common coupling (PCC) in power grid can be in terms of reliability and voltage quality. When one talks about voltage quality, impact of RES on PCC can be in different aspects. The most influential parameters are: voltage variations, voltage unbalance, flickers and total harmonic distortion (THD). RES impact on PCC depends on distributed generator type and strength of the grid (short circuit current and rated current of generator ratio) in PCC. Evaluation of RES impact on PCC regarding voltage quality must be performed considering some Norms (Standards) and/or Regulations. This paper deals with impact of two photovoltaic (PV) plants with equal characteristics, one connected in strong (urban area) and second one in weak (rural area) distribution grid in PCC. The impact is considered through analysis the most vulnerable voltage quality parameters, mentioned above.