​IEEE standard 1547-2003 governing distributed energy resources (DER) interconnections was written focusing on ensuring that DER did not interfere with the normal operation of the distribution system’s regulation and protection systems. Now that growth in DER is having significant impact on systems, IEEE 1547-2018 was developed to ensure Bulk Power System (BPS) dynamic and transient stability. This Guide helps explain the changes and new features in the 1547-2018 standard and associated effects on cooperatives.