High Penetration of Photovoltaic Generation Study: Flagstaff Community Power. Final Technical Report: Results of Phase 1.

摘要

Arizona Public Service Company (APS) expects that by 2027, renewable energy will account for 6,590 GWh in energy consumption by its customers. While much of this future energy will come from large centrally-located power plants, distributed renewable energy, sited at the point of end-use will also play an important role in meeting the needs of APS customers and is expected to provide 1,734 GWh. With increasing penetration of residential and commercial photovoltaic (PV) systems at the point of end-use, PV power generation not only offsets the load, but could also cause significant shifts in power flow patterns through the distribution system, and could possibly cause reversal of flow through some branches of a distribution circuit. Significant changes to power flow introduced into existing distribution systems due to the increased amount of PV systems may cause operational issues, including over-voltage on the distribution feeder (loss of voltage regulation) and incorrect operation of control equipment, which may lead to an increase in the number of operations and related equipment wear that could affect equipment reliability and customer power quality. Additionally, connecting generation resources to a distribution feeder can introduce additional sources of short-circuit current to the distribution system. This could potentially result in increased short-circuit currents, potentially reaching damaging levels, causing protection desensitization and a potential loss of protection coordination. These effects may be further compounded by variability of PV production due to shading by clouds. The effects of these phenomena in distributed PV applications are not well understood, and there is a great need to characterize this variability. This project will contribute to understanding the effects of high-penetration solar electricity on the design and operation of distribution systems by demonstrating how a high penetration of PV systems affects grid operations of a working, utility distribution feeder. To address the technical challenges related to the integration of distributed PV when PV penetration levels reach or exceed 30% of the total load, technologies and methods to ensure the stable and safe operation of the feeder will be evaluated.