Power System Restoration

1
Power System Restoration

• Kevin Schneider, Chen-Ching Liu
• University of Washington
• Department of Electrical Engineering

2
Overview
3
Restoration Constraints

• Main power converter startup time
• Communications start up time
• Maximum dv/dt
• Node voltage limits

4
Main Power Converter Startup Time

• 10-15 second startup delay from when power is
  applied to the backbone
• During this time
• Startup supply capacitor charges to 48V
• SCRs begin to fire at 45V
• Startup power supply energized
• Main power converter control circuits energized

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Communications Startup Time

• Approximately ½ to 1 minute for the
  communications system to power up

6
Maximum DV/DT

• PN junctions in solid state components are
  sensitive to high values of DV/DT
• DI/DT will not be a concern for the NEPTUNE
  systems backbone solid state components

7
Node Voltage Limits

• If node voltage drops below 5600V the control
  circuit will drop out and the converter will turn
  off
• Voltage cannot exceed certain levels or there
  could be arc over
• There will be an acceptable band of operation
  that must be adhered to

8
Security Analysis
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Security Analysis Cont.

• Switching Action- For a restorative action there
  may be several possible ways to restore the
  system.
• Feasibility- A portion of these actions will
  place the system in insecure configuration for
  some period of time. Only switch actions which
  do not violate any constraint can be allowed.

Note a system may meet all 4 constrains but be
operating in an insecure condition
10
Contingency Selection

• Before a switching action is performed the effect
  of the following must be considered for the new
  topology
• Loss of shore station
• Loss of shallow water links or deep water links
• Significant load increase
• Node failures
• Others

11
Black Start Example

• Only the shore stations have power
• After a node is fully energized, 4 kW of
  scientific load is applied to that node

12
System Start-up From Black Start Ensuring Voltage
Limits
Victoria
18V
72V
185V
Nedonna Beach
942
13
Summary

• Before every switching action
• Ensure all 4 constraints are meet
• Ensure transition is to a secure situation