Power System Restoration

Kevin Schneider, Chen-Ching Liu

University of Washington

Department of Electrical Engineering

Overview

Voltage, Current, Power Limit Checking

Status Data and Analog Measurements

All Operating Constraints Satisfied Operating

Constraint's) Violated

Emergency Control /Load Management

Security Assessment System Restoration

Loss of Load

Restoration Constraints

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

Main Power Converter Startup Time

10-15 second startup delay from when power is applied to the backbone

During this time:o Startup supply capacitor charges to 48Vo SCRs begin to fire at 45Vo Startup power supply energizedo Main power converter control circuits

energized

Communications Startup Time

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

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

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

Security Analysis

Secure

Insecure

Emergency RestorativeEmergency Control Action

RestorativeControl Action

Normal Conditions

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

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

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

Victoria

Nedonna Beach

System Start-up From Black Start

Ensuring Voltage Limits

942

185V

72V18V

Summary

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