2.5 What Could or Should Other Jurisdictions Do?

2.5.3 “My jurisdiction is starting to see distribution problems related to DER systems but utilities are concerned about using these new advanced DER functionalities. What could the Hawaii, Europe, and other high penetration experiences help us with?”

The use of the advanced DER functionalities is still in its infancy. Although some basic understandings have been developed, it is clear that additional research is necessary, particularly for anomalous or emergency situations. Some possible issues to explore in this situation are:

• PG&E does interconnect DER systems up to 20 MW on its 21 kV system (using dedicated feeders) since 21 kV feeders can be designed to accommodate the larger DG.   Since the interconnection impacts are mitigated prior to interconnection for these large systems, PG&E does not have the problems that Hawaii experienced, even though PG&E does have feeders with over 100% DER penetration, and back-feeding of the transmission system does occur at a few locations.  From a power engineering perspective, reverse flow into the transmission system is not a problem so long as the impacts are mitigated prior to interconnection. 
• Utilities can explore the use of other feeder equipment, such as static var compensators, to determine if these are more cost-effective and more reliable for handling voltage problems than DER systems using either fixed power factors or dynamic volt-var control.
• Some utilities are undertaking research and lab projects to try to better understand the impacts, both good and bad, of the advanced DER functionalities. The results of these efforts could be provided to other utilities and/or used as a basis for further pilot projects.
• Utilities could partner with other stakeholders to explore specific issues, such as coordination of DER volt-var capabilities with the utility feeder equipment and determining the most appropriate DER voltage ride-through settings for ensuring safety as well as reliability of service.

• Utilities could review both the Hawaiian situation and the European situations where high penetrations of DER are being experienced. These differences in situations have to be carefully assessed before they can be applied to other situations, since Hawaii is an island, while the distribution systems of Europe have very different configurations to US distribution systems . That said, Hawaii (see 3.5.3) is permitting far more DER generation on its feeders than in most other locations, and, with support from DER systems that can “cease to energize” at high voltage levels, can ride-through over-voltage situations.