Bulk Electric System Power Outages and Restoration Considerations Peter Heiman Western Area Power Administration (Desert Southwest Region) 1

 What are they? –A blackout is a condition where a major portion or all of an electrical network is de-energized with much of the system tied together through closed breakers  What causes blackouts? –A combination of circumstances that stress the Bulk Electric System beyond its capability Natural phenomena (such as severe storms) Human error (including poor maintenance practices) Equipment malfunction (inadequate design/protection schemes) –Tools/Trees/Training 2

 How frequent are they? –Serious power interruptions or blackouts occur at the rate of about 35 a year in the US –Half of these (on average) exceed 100 MW and involve up to 45,000 customers at a time  Notable US Blackouts –November 9, 1965 (NERC created) –July 2 and August 10, 1996 –August 14,

 Concerns/Impacts –Any widespread electric outage draws a lot of attention from: Politicians, Governmental agencies Consumer advocates, Environmentalists Large customers Media –Impacts: Business (Loss of productivity, Product, and Property) Health Issues (Food contamination, Medication problems, Anxiety) Safety (Traffic accidents, Civil unrest) 4

 System Restoration Plans –Regionally (Reliability Coordinator Plan coordinating the restoration efforts of Balancing Authorities) NERC Standard EOP (Reliability Coordination System Restoration) LRCC Restoration Plan for the Desert Southwest Sub- Region –Maintain a database that contains all blackstart generators used for system restoration within it’s respective area –Database includes: name, location, megawatt capacity, type of unit, latest date of test, and starting method 5

 System Restoration Plans –Locally (Each Balancing Authority) NERC Standard EOP (System Restoration Plans) DSW Blackstart and Bulk System Restoration –Generators –Adjacent Balancing Authorities –Sub-Balancing Authorities 6

 Basic Steps during Restoration –Determine Status of your System –Stabilize what remains of the System –Communicate System Status –Restore Strongest ties first –Jointly agree to Resume normal operations –Make proper Notifications 7

 Concerns during Restoration –System Status Visibility of the System (System Control And Data Acquisition (SCADA) and Remote Terminal Unit (RTU) status) –Communication Voice communication with field personnel and adjacent Balancing Authorities 8

 Concerns during Restoration –Voltage Control High line voltage conditions (Ferranti Rise) Switching Surges (Transient Over-voltages) –Protective Relaying Reduced Fault Current Improper setting for restoration conditions 9

 Concerns during Restoration –Frequency Control Place governor control at zero droop (isochronous) Start with frequency slightly elevated Pick up small (5-10 MW) blocks of load –Load Restoration Cold Load Pickup –Loss of Load Diversity –Motor In-rush Current 10

Questions? 11