3.5 Examples of DER Grid Codes for Advanced Functions

3.5.5 Impact on Independent System Operators (ISOs) and Regional Transmission Operators (RTOs)

The capabilities of smart inverters to solve power system problems are also being picked up by Independent System Operators (ISOs) and Regional Transmission Operators (RTOs). These companies are regulated by the Federal Energy Regulatory Commission (FERC).

For example, PJM has recently (March 6, 2015) requested that FERC revise the Open Access Transmission Tariff to incorporate changes  to PJM’s generator interconnection rules to require “enhanced inverter” capabilities be utilized by prospective Interconnection Customers contemplating the interconnection of wind and other non-synchronous generation facilities . PJM has requested that this filing become effective on May 1, 2015. In justification, this filing states,

“In addition, traditional interconnection settings relative to long-term system fluctuations for variable generation resources has been historically very conservative, typically resulting in such units “tripping” off-line during relatively minor frequency and voltage system events. For many years, engineering standards – most notably the Institute of Electrical and Electronics Engineers (“IEEE”) standard 1547- have prescribed that variable energy resources should trip or cease to energize in an effort to protect the resource whenever a contingency would drive frequency or voltage out of its normal operating range (i.e. a “must trip” requirement). However, in more recent years, the expected performance of these units during and after system disturbances has been re-evaluated and the need for mandatory “ride-through” requirements for variable energy resources in particular has been expressed by the North American Electric Reliability Corporation (“NERC”),acknowledged by the IEEE in their more recent IEEE 1547a standard.”