The Effect of Three-phase Voltage Imbalance at PCC on Solar Panel Output Power

AbstractPhotovoltaic generation is one of the promising renewable sources and is deployed in more and more power systems. Like other distributed generation, solar panels are connected to distribution systems instead of transmission systems. Distribution systems are inherently unbalanced, so the power flow studies must consider three phases. The interface between solar panel and distribution system is a DC-DC converter and an inverter, which are normally designed provided that the system is balanced. This paper analyses the output power of solar panel under both balanced and unbalanced PCC voltages and found the three-phase powers are not equal and unity power factor control cannot be realized when PCC voltages are unbalanced while the controller works well when PCC voltages are balanced. The results of simulation conform to the analysis. The work of this paper shows that simple P-Q solar panel models are not good for distribution system power flow studies, and present unity power factor controller does not work well for solar panel connected to distribution systems