Transcript Electronics at the Core Layer of Power Flow Control

Control of the SuperGrid
Crowne Plaza Cabana Palo Alto Hotel
Palo Alto, California, November 6-8, 2002
Bob Lasseter
University of Wisconsin-Madison
XX - 1
Long range assumptions
•
•
•
•
Looking 20-50 years ahead
Environmental issues will increase
Pressures to reduce carbon fuels
Address both transportation and
stationary energy needs
XX - 2
Continental SuperGrid
ac/dc
dc/ac
dc/ac
ac/dc
DC Grid
dc/ac
ac/dc
dc/ac
Load
Load
Load
Load
• Nuclear generation (other none carbon sources of energy)
• Hydrogen cooled superconducting grid
• DC network (power electronics & losses)
XX - 3
DC Superconducting Network
System:
Low voltage high current superconducting network
(unit connected generation>DC>distribution)
Issues
•Complexity of System control (100s of sources and 100,000s
•Current control
loads)
References:
Johnson,B.K., R.H. Lasseter, F.L. Alvarado, D.M. Divan, H. Singh, M.C. Chandorkar, and R. Adapa,
"High-Temperature Superconducting dc Networks", IEEE Transactions On Applied Superconductivity,
Vol. 4, No.3, pp.115-120, September 1994.
Tang, W and R.H.Lasseter, "An LVDC Industrial Power Distribution System without Central Control Unit,"
PECS , Ireland, June 2000.
XX - 4
How to handle load power needs
100s of rectifiers
100,000s inverters
• AC systems; frequency droop
• Complexity of power flow control
• Need distributed control
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Distributed Control Issues
Rectifiers (generation or storage)
• Change power output depending on load.
• Share load
• Independent of number
Inverters
• Provides stable ac voltage to the load
• Provide required power for loads
• Automatic load shedding
Coordination is achieved through dc voltage
XX - 6
Control of injected current
"R"

V()
3

i1
X ac
i2

Thyristor Controlled Rectifier

Vdc  V ( ) 
3

X ac Idc
Assume no resistance in line
(some ac losses due to harmonics)

XX - 7
Power Dispatch on dc voltage
Vdc
IdcMax

IdcMax

IdcMax

XX - 8
Power Dispatch on dc voltage
Vdc
IdcMax
IdcMax
IdcMax
Load shedding area



XX - 9
Single system voltage used for
load tracking control
Inv2
Vac
Inv3
Inv1
All inverters
I dc
Vdc
I max
2 inverters
Rectifier
Vdc
XX - 10
Superconducting Network
System:
Low voltage high current superconducting network
(generation>DC>distribution)
Issues
•System control
•Current control
References:
Johnson,B.K., R.H. Lasseter, F.L. Alvarado, D.M. Divan, H. Singh, M.C. Chandorkar, and R.
Adapa, "High-Temperature Superconducting dc Networks", IEEE Transactions On Applied
Superconductivity, Vol. 4, No.3, pp.115-120, September 1994.
Tang, W and R.H.Lasseter, "An LVDC Industrial Power Distribution System without Central
Control Unit," PECS , Ireland, June 2000.
XX - 11
Current levels in superconductors
i1

i2
Current flow is a function of V over time and the
line inductance.

In steady state there 
is a single dc voltage across
the system(some ac losses due to harmonics)
XX - 12
Issues:Control of grid currents
Load
Load
DC grid
Load
Load
•Currents in segments are defined by past transients (no
unique steady state)
•Issues of over-currents in segments and faults
•Adding a de-energized segment
Need current control devices for each segment
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Superconducting Network
• Power flow control is distributed
• Network current control requires new
devices*(superconducting current transfer device)
• Point-to-point only transmission
• Storage needed near loads
• Ideal transport of H2
*Johnson,B.K., R.H. Lasseter, F.L. Alvarado, and R.Adapa, "Superconducting Current
Transfer Devices for Use with a Superconducting LVdc Mesh", IEEE Transactions on
Applied Superconductivity, Vol. 4, No. 4, pp. 216-222, December 1994.
XX - 14
Ratio of H2 to electricity?
• For superconductor cooling only?
• Include transportation and stationary
energy needs?
• Generate some H2 at source and some
at load?
• Two pipelines?
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Hydrogen only grid?
• Clusters of microgrids with H2 generators
• Small generation placed near the heat
and electrical loads allows for reduncey
• The combined heat and power
efficiencies can approach 95%
• Transportation is integral to system.
• Technology issues for H2 grid & storage.
XX - 16
Hydrogen MicroGrid with CHP
Dormitory A
Dormitory B
Administrative
Building
Hydrogen
500 kVA
Generator
Step Up
Transforme
r
Paralleling Bus (4.8 kV)
Generator
Protection
and
Control
Load
control
Heat Recovered
from ICE Units
300 kVA
500 kVA
To Other
Campus
Loads
Heat Distribution
75 kVA
Student
Union
Campus Owned
Distribution (13.2
kV)
Voltage
Regulator
Academic
Building B
Communication & Control Signal Path
1.75
MVA
HG
1.75
MVA
HG
1.75
MVA
HG
Academic Building
A
800 kVA
300
kVA
Heat Distribution
XX - 17
MicroGrids in each building
Hydrogen
storage
H2 electric generators are placed at the point of
use to provide both electricity and heat
Reference
(http/certs.lbl.gov/)
“Integration of Distributed Energy Resources: The CERTS MicroGrid Concept,”
R. Lasseter, A. Akhil, C. Marnay, J. Stephens, A.S. Meliopoulous, R. Yinger, and J. Eto
April 2002
XX - 18
Issues
• How to distribute H2 ?
• Superconducting current control?
• Grid vs. point-to-point?
• H2 line independent from
superconducting line.
• H2 microgrids
XX - 19
Possibilities
Today
• Natural gas microgrids > H2 base
• Point-to-point dc superconductor
XX - 20