Coordinating generator protection with transmission protection and generator control — NERC standards and pending requirements

Recent misoperations of generation protection during major system disturbances have highlighted the need for better coordination of generator protection with generator capability, generator Automatic Voltage Regulator (AVR) control and transmission system protection. Generator protection misoperations contributed to the 1996 outages in the western U.S. and played a key role in the 2003 U.S. East Coast blackout. Since most recent major power system disturbances are the result of voltage collapse, generator protection must be secure during low voltage system conditions while still providing generator protection. The generator AVR needs to properly control VAr support to rapidly stabilize system voltage during major disturbances. In addition, turbine control should not trip generators for recoverable undervoltage conditions. As a result of the 2003 blackouts, NERC (North Electric Reliability Council) has developed protection standards that generator operators and owner must follow. NERC is also conducting audits to ensure that generator owners and operators are meeting those standards. These standards also address maintenance of the generator protection system.