The power quality impact from the photovoltaic rooftop to the grid distribution system using PSCAD/EMTD

Abstract

The general trend in the past 10 years of increasing PV system efficiency, low PV system prices, attractive government motivation programs, and other interesting factors have joined synergistically to reduce the block of access for PV systems to have an influence in the market and to develop their commitment to the worldwide vitality portfolio. In the same way, the abnormal situations of power quality which link the PV systems to the distribution network are becoming an important problem as the PV penetration level is increasing continually. This thesis proposes an impact analysis of power quality from PV rooftop systems integrated with a very small power producer (VSPP) installed capacity of 1 MW, which was associated with the Provincial Electricity Authority (PEA's) distribution network. The power quality information is collected by the power quality analyzer at the Point Common Coupling (PCC) of PEA distribution line 22 kV by 7 days then the design, modeling, and analysis of PV rooftop system connected to the distribution system based on real data from measurement were performed in the PSCAD/EMTDC software simulation. In addition, the simulations in ferroresonance abnormal cases were also implemented. The simulation system comprises of the PV rooftop system, capacitance in long line, nonlinear saturated distribution transformer core, and a single phase switching breaker connected to the grid distribution system. From the monitored data, it was found that the highest power yield was 778.125 kW while the simulation result was 815 kW. Moreover, based on the PEA standard EN 50160 with the cumulative percentile at 95Percent of power quality measurement for PV rooftop system, the measured data showed that the power quality of the PV rooftop system passed the PEA regulations for its distribution network connecting system. From the simulation result, it showed that the ferroresonance phenomenon will occur if a single phase switching breaker was switched one by one and the transformer core was saturated causing the overvoltage, overcurrent, and the destruction of the distribution transformer and other apparatus in the distribution network. This important phenomenon can help the operators for future maintenance and operations to protect the disrupted distribution network.