Analytical Study of the Effects of Grid Resistance on Grid-Connected PV Systems: Modeling and Simulation

Renewable energy systems have become common in power systems. Many problems associated with connecting a renewable energy system to utility network have arisen. In the traditional power calculation, the resistance of the line is ignored because of large the X/R ratio. However, the R/X ratio in the distribution network is greater than in transmission. Because of that, the line resistance should be considered in the power calculations. In this paper, the effect of the grid resistance on transfer of power is investigated by calculating the active power between a PV system and the grid where the grid resistance is included. Two models were developed to study the effects of the grid resistance. The sensitivity of real and reactive power to the grid impedance, the current performance and the phase angle for the maximum power were studied under variations of the grid resistance. The results from both models have been compared to emphasize that the transfer of power is really influenced by the resistance of the line impedance.