Transmission Conference
December 15, 2004, Pittsburgh
Transmission Operation:
Time for Paradigm Shift?
Felix Wu
The University of Hong Kong and
University of California, Berkeley
Restructuring
Unbundling
Customer
Service
Distribution
Transmission
Generation
Customer
Service
Distribution
Broker/
Merchant
Transmission Function
System
Operations
Generation
ƒ Generation
competition
ƒ Transmission open
access
ƒ Customer choice
Transmission Operation
ƒ Traditional practice
ƒ Congestion management
ƒ…
ƒ…
Is the traditional transmission operation
evolved for the vertically integrated monopoly
compatible to the restructured industry?
Old Paradigm
ƒ Philosophy
» Preventive control
» (n-1) criterion
ƒ Operational planning
» Setting limits
– Physical
– Stability, ….
ƒ Real-time operation
» Security-constrained dispatch
» Contingency analysis and re-dispatch
Justification
ƒ (n-1) criterion
» Obligation to serve
ƒ Preventive control
» Reliability justification for capital investment
» Cost redistribution within a company
» Technology not possible for post-contingency
control
Prediction:
Blackout will happen again.
Can blackout be avoided?
Yes.
old approach
alternative approach
August 14, 2003 blackout happened.
Load Shedding
ƒ Power balance
ƒ Protective relays
disconnect
» Fundamental physical
law
» Spatial and temporal
ƒ Power imbalance
» Generators
» Transmission lines
ƒ Cascading outages
causes
» Overload
» Instability
ƒ Control strategy
» Remove imbalance
ƒ
result in blackout
Load shedding is the
most effective
measure for blackout
prevention
Alternative Approach
ƒ Value of service (load demand)
ƒ Preventive control = $$
» Supply-side measures
ƒ Load shedding = $$
» Demand-side measures
ƒ Value balance
» Stochastic
ƒ Post-contingency control
Feasibility (1)
ƒ Post-contingency control
» Control center: RTU/SCADA
EMS Control Center
Communications
Device
Power Station
S y s te m
S e rv e r
A lt e r n a t e
S y s te m
S e rv e r
A lt e r n a t e
C o m m u n ic a t io n s
G a te w a y
C o m m u n ic a t io n s
G a te w a y
D u a l R e d u n d a n t
S y s te m N e tw o rk
Bridge to
A d v a n ce d
A p p lic a t io n s
S e rv e r
Corporate LAN
F a ilo v e r
L o g ic
State
Monitor
Encoder /
Decoder
Control
Driver
D is p a t c h e r s
W it h
W o r k s t a t io n s
SCADA Remote Terminal
» New: PMU/WAMS
Control
Center
Measuring
Device
Feasibility (2)
ƒ Load shedding
» Traditional: Under-frequency, under voltage
» New: Direct load control
ƒ Value of service
» Interruptible load
» Priority service
Conclusion
ƒ The philosophy underlining traditional
ƒ
ƒ
transmission operation is rooted in an industry that
is a vertically integrated monopoly.
A fresh look at the transmission reliability practice
seems warranted.
We propose a new approach based on:
» Value of service
» Post-contingency control
ƒ Post-contingency control is on the verge of being
technically feasible. There were programs on the
value of service.
Center for Electrical Energy System
The University of Hong Kong
http://www.eee.hku.hk/~cees