Introduction

1. Local Load Power Factor Correction by Grid-Interactive PV InvertersWenxin Peng†,Yahia Baghzouz†, Salim Haddad‡(†)University of Nevada, Las Vegas (USA), (‡)University of Skikda, Skikda (Algeria) (b) Introduction PSCAD Model of PV System with VAR Generation Capability. PV systems are characterized as intermittent power sources, dependent on the fluctuating sunlight. In addition, conventional PV systems currently operate at unity power factor, regardless of the local reactive power needs. PV inverter technology has the potential to provide significant added value by integrating advanced control functions that can provide beneficial grid support such as a source of reactive power Reactive Power Generation & VAR Control Methodologies The reactive power of the PV inverter can be controlled such that the inverter does not exceed its kVA rating. The figure below shows the Power Generation Duration Curve (PGDC) of a 2.5 kW PV system and the corresponding reactive power availability. VAR production is made possible by advancing the generated current waveform with respect to the utility voltage waveform by some angle. • To improve the operating power factor of the feeder, two cases are considered: • Case A - the inverters supply all their reactive power capacity during the daylight hours. • Case B - the inverters operate at constant power factor of 70.7%, then switch to Case A when they reach their VAR generation capability. Simulated PV Inverter Active and Reactive Power Generation The solar irradiance is assumed to drop by 20% every second starting from the peak value, and the inverter rating is 2.5 kVA. Case A Case B Impact of PV Penetration on Local Feeder Load Characteristics PV systems that operate at unity power factor lead to lower power factor during the daylight hours as show in the figure below (10% PV penetration), thus lower distribution system operating efficiency. Case A Conclusions In distribution feeders with significant PV penetration, VAR generation from inverters may be needed during some parts of the day to restore the operating power factor. Simple local VAR control using either constant kVA or constant power factor control is shown to provide satisfactory results. VAR generation by a PV inverter, however, will slightly reduce the efficiency of the overall PV system during daylight (due to higher current generation). Case B