Facility Connection RequirementsMay 1, 2005
II. E. Generator Protection Requirements
Generators connecting to the FPL-NED transmission system are responsible for protecting those facilities from electrical faults and other hazardous conditions. Generator interconnections must be equipped with circuit breakers or other appropriate interrupting devices to protect those facilities. The generator owner must provide and own the primary circuit breaker or other interrupting device that protects the facility and disconnects it from the FPL-NED transmission system. The primary purpose of this interrupting device is to protect the generating plant facility. A joint use circuit breaker that protects both generating unit and transmission circuit facilities as its primary function is highly discouraged.
Synchronous generators connected to the FPL-NED transmission system should be able to withstand certain temporary excursions in voltage, frequency, reactive and real power output without tripping. This is required to support the grid and avoid cascading events.
Synchronous generators shall have the generator’s protection and controls set in accordance with all applicable ISO-NE and NPCC requirements for variation in grid voltage and frequency.
Generators must be designed to remain on line for normal clearing system faults within the close proximity to the plant switchyard. Voltage may approach zero at the switchyard bus for six cycles for some types of faults. Control systems, contactors, motors and auxiliary loads that are critical to the operation of the plant must have ride through capability where needed to avoid generator tripping for close-in faults as described above. Additionally, generator protection systems such as the Load Drop Anticipator, Early Valve Actuator or Power Load Unbalance should not be designed to trip a generator for normal clearing external faults or stable swings.
It is recognized that certain circumstances may exist that necessitate the imposition of performance criteria that is considered more stringent than the default criteria specified above. Such circumstances shall be identified during the conduct of the System Impact Study or Operational Studies for each particular generator.
II. F. Support of the Grid
All synchronous generators connected to the FPL-NED transmission system are to be equipped with automatic voltage regulators (AVR)2. Generators must operate with their excitation system in the automatic voltage control mode unless otherwise approved by FPL-NED. Generating equipment owners shall maintain a log which records the date, time, duration and reason for not being in the automatic voltage control mode when operating in parallel with the FPL-NED system. Generating equipment owners shall make this log available to FPL-NED on request. Appendix 2 has additional details for reporting of AVR status and voltage schedule deviations.
2 Items G1, G2, G3, and G4 are requirements of NERC Planning Standards, section III. C.