Reactive power considerations in reliability analysis of solar photovoltaic systems

Abstract

Reliability is one of the key aspects of power system operation and therefore reliability analysis techniques are well developed. However reliability analysis conventionally takes into account active power and limited attention has been given to reactive power. Reactive power is very essential in maintaining voltage stability of power systems. The voltage constraint at network can restricts active power delivery to the loads and could result in forced load curtailment. This research investigates the effect of reactive power shortage on reliability of power systems with significant penetration of PV cells. The reactive power issues become more significant in distributed generation using renewable energy sources such as photovoltaic (PV) Cells, which operate mostly at unity power factor. The IEEE 14-Bus system is utilized to perform this study. Twenty four state PV generation model was developed based on 24-hour solar radiation trend. Reliability indices are calculated analytically and verified through simulation without considering reactive power shortage. Next, a measure of Expected Energy Not Supplied (EENS) on account of reactive power shortage and voltage violation in network is calculated. Monte Carlo simulation was performed in MATLAB environment, where simulation results are compared with the case without taking into account reactive power and voltage violation. This research suggests that placement of the PV in the network can greatly reduce active and reactive power shortage during the contingencies. The reactive power is studied here from design and planning perspectives for reliable and stable power system operation when high penetrations of PV energy sources are present.