Novel Control of Grid Connected Photovoltaic (PV) Solar Farm for Improving Transient Stability and Transmission Limits Both During Night and Day

摘要

Lack of adequate transmission capacity is a major impediment in connecting more of renewable energy sources (wind, solar) into the transmission grid. This paper presents a novel control of a grid connected photovoltaic solar farm to improve transient stability limit and hence improved power transfer capability of the transmission line. In the night, when the solar farm is completely idle, this new control technique makes the solar farm inverter behave like a STATCOM - a Flexible AC Transmission System (FACTS) device. The solar farm inverter then provides voltage regulation at the point of common coupling and improves the stability and transfer limits far beyond minimal incremental benefits. During the day also, when solar farm is producing real power, this new control strategy makes the solar farm inverter provide voltage control with the remaining inverter MVA capacity (after meeting the requirements of real power generation) and thereby increases power transfer limits substantially. Transient stability studies are performed for a realistic single machine infinite bus (SM1B) power transmission system with a PV solar farm located at the line midpoint, utilizing EMTDC/PSCAD simulation software. This paper thus presents a novel utilization of an existing solar farm asset both during night and day time to improve power transmission limits which would have otherwise required expensive additional equipment such as, series/shunt capacitors, or separate Flexible AC Transmission System (FACTS) devices.