1. NERC Published Lessons Learned
April 2017

2. NERC Lessons Learned
One Lessons Learned (LL) was published in April 2017
LL Dispatched Reduction in Generation Output Causes Frequency Deviation

3. Dispatch Causes Frequency Deviation - Details
Inadequate data definition resulted in transfer of incomplete data to security-constrained economic dispatch unit commitment software
This resulted in undesirable unit commitment outputs from the BA’s dispatch software
SOs attempted to intervene, however, some dispatch instructions could not be blocked or overridden
There was a large reduction in generation output that caused the BA’s ACE and system frequency to deviate for almost 20 minutes

4. Dispatch Causes Frequency Deviation

5. Dispatch Causes Frequency Deviation

6. Dispatch Causes Frequency Deviation – Corrective Actions
Resolve the data transfer design that led to the data inconsistency in the unit commitment software
Improve existing automated controls to block dispatches that exceed certain criteria
Improve SO manual intervention capabilities
Entity developed additional manual controls for SOs and support personnel until software and automation improvements can be implemented
SOs involved in the event developed lessons learned training for SOs and support personnel

7. Dispatch Causes Frequency Deviation – Lessons
Automated & manual controls for dispatch software should be reviewed, tested, and SOs trained in its use periodically under various conditions
SO and/or GOPs should be able to intervene to override automated dispatch signals
BAs should review ramp rates of fast-ramping resources and determine the ramping that can be absorbed at steady state
SOs & support staff should have guidance & training on troubleshooting security-constrained economic dispatch software issues

8. Lessons Learned Survey Link
NERC’s goal with publishing lessons learned is to provide industry with technical and understandable information that assists them with maintaining the reliability of the bulk power system
NERC requests that industry provide input on lessons learned by taking the short survey. A link is provided in the PDF version of each Lesson Learned

9. Hassan Hamdar hhamdar@frcc.com