For the second time in as many months, the Federal Energy Regulatory Commission (FERC) acted to eliminate undue discrimination between electric generators. Last month, FERC issued Order No. 827, which required non-synchronous (wind) generators to provide dynamic reactive power to their interconnected transmission provider in a manner comparable to that provided by synchronous generators. (See our June 20, 2016 alert.) This month, FERC determined that there was no technological or economic basis to have different voltage and frequency ride through requirements for small (20 MW or less) and large (greater than 20 MW) generators. FERC issued Order No. 828, which requires small generators that seek a new or modified interconnection to the transmission grid after the effective date of the order to (1) have frequency ride through and voltage ride through capabilities requiring connection and synchronization during system disturbances, and (2) not disconnect automatically or instantaneously from the transmission grid for an under- or over-frequency condition or an under- or over-voltage condition.
FERC reasoned that as the number of small generators on the grid has increased, their impact on the grid has changed. FERC noted the growth in grid-connected solar photovoltaic generation and other small generators due to state renewable portfolio standards, the development of new technologies, and the reduction in cost for solar panels. FERC also cited North American Electric Reliability Corporation reports noting that the high penetration of distributed energy resources will impact the reliability of the grid if action is not taken to mitigate potential adverse impacts. The absence of ride through requirements for small generators increases the risk, FERC states, that an initial voltage or frequency disturbance could be exacerbated by a significant number of small generators tripping off the grid. And FERC added that technological advances, such as smart inverters, allow small generators to ride through frequency and voltage disturbances.
FERC stressed that the requirements in Order No. 828 are not intended to interfere with state interconnection procedures. In the order, FERC also amended the compliance deadline for Order No. 827 reported in last month's alert, to allow transmission providers to revise their tariffs to incorporate the new requirements of Order Nos. 827 and 828 in a single compliance filing. FERC will issue a notice of the single compliance date after publication of Order No. 828 in the Federal Register.