Operating and Planning the US & China
Grids for Reliability and Economic
Efficiency to Enable Optimal Use of Smart
Grid
Presented at
International Symposium on Smart Grid and
Renewable Generation Impacts on the Power System
Taiwan National University, Institute of Applied Mechanics
Taipei
by
Robert Blohm卜若柏
Member
North American Electric Reliability Corp. (NERC)
Managing Director
KEEN Resources Asia Ltd.
http://www.blohm.cnc.net
November 18, 2010年11月28日
1
OUTLINE
1. How the electric grid is planned and operated determines
which Smart Grid investments will be made. Planning and
operating models
2. Planning models.
3. Operating models
4. Challenges in grid configuration and management
5. Challenges for Mainland China
2
1. How the electric grid is planned
and operated determines which
Smart Grid investments will be
made. Planning and operating
models
• are based on:
– power-flow model. Model of electricity flow on the system
in response to changes in system components.
– models to forecast
• economic/scheduled usage and
• contingencies/emergencies.
• are combined with 2 economic efficiency principles
– choosing the least-cost (or market-chosen) alternative
project
– economic transfer from the causer of the cost to the bearer
3
of the cost
2. Planning models. Competitive
market time horizon: less than 5
years. Two kinds often confused
together.
• Economic. Of scheduled power.
– Based on an economic forecasting model
and a targeted, controlled LOLP (loss-ofload probability)
– Criticism:
• biased toward excess supply
• ignores price-rationing
• attempts to target an unstated low price not
clearly related to LOLP.
4
2. Planning models. Competitive
market time horizon: less than 5
years. Two kinds often confused
together. (cont.d)
• Reliability. Transmission. Of unscheduled
power.
– Criticism: usually based on robustness to any
contingency (a fault or loss of any element)
without regard to probability of occurrence.
• Probability must be based on historical data. The US still
doesn’t have a complete database
– NERC has a generation outage database, whose software
was translated by China in the 1980s
– DOE has a transmission outage database but no load loss
database
• Two events could be more probable than a single one
5
2. Planning models. Competitive
market time horizon: less than 5
years. Two kinds often confused
together. (cont.d)
• Reliability. Transmission. Of unscheduled power.
(cont.d)
– Used to determine TRM (transmission reliability margin) to
subtract from TTC (total transmission capacity) to get ATC
(available transmission capacity)
– TRM is designed to meet the NERC performance
requirement of withstanding
• a single uncontrolled contingency, and
• a second controlled contingency to prevent an uncontrolled
contingency
– Reliability is strictly defined as avoidance of uncontrolled
6
outages
3. Operating models
•
Transmission.
– Economic. Rationing of ATC (available transmission
capacity) by redispatch when there is congestion. By
•
•
out-of-“merit”-order dispatch of generation (SEE NEXT SLIDE), and
possibly by
allocation of FTRs (fixed transmission rights) in markets.
– Reliability. Based in the US on the IDC (interchange distribution
calculator) which is a DC model of the powerflow identifying source and
sink and updated every hour (but updatable every minute).
•
•
•
Invocation of TLR (transmission loading relief) to reroute/redispatch power in the
event of a contingency.
(Under development) Allocation of unscheduled congestion by ACE Distribution
Factors. Allocation of allowable ACE by IDC distribution factors determined by
Kirchoff’s law.
Generation.
– Economic. By “merit” order of
•
•
least cost (“system lambda”) in non-markets, or
least LMP (“locational marginal price”) in markets
7
price
Only physical/forward transmission
rights can prevent generators from
capturing congestion rents from
transmission owners. Cannot be
prevented by congestion contracts
that value congested transmission as
the difference in energy prices
across the congested interface.
Generators on the
cheap side of the
constraint collude
to raise prices to
capture congestion
rents from
transmission owner
congested price to consumer on expensive side
of constraint
Congestion charge
normally to
transmission owners
Supply curve
energy price to generator on cheap side
of constraint
Demand curve
congestion
quantity
3. Operating models (cont.d)
• Generation (cont.d)
– Frequency control. Dispatch of power generation held as
“reliability reserve”
• Definition. Balancing of unscheduled supply (generation) and
demand (load), measured by closeness to scheduled frequency (60
Hz in US, 50 Hz in China).
– Upward deviation
• High frequency means insufficient supply
• Excessive high frequency means surge in power flow which spreads
throughout the system (SEE NEXT SLIDE)
– Downward deviation
• Low frequency means insufficient load
• Excessive low frequency means generator vibration and explosion
9
Time on August 14, 2003
15:15:38
15:15:16
15:14:56
15:14:26
15:14:03
15:13:40
15:13:18
15:12:53
15:12:32
15:12:06
15:11:42
15:11:22
15:10:58
15:10:38
15:10:12
15:09:52
15:09:30
15:09:06
15:08:46
15:08:20
15:08:00
15:07:36
15:07:16
15:06:54
15:06:30
15:06:08
15:05:42
Hertz
Eastern Interconnection Blackout
60.3
60.25
60.2
60.15
60.1
60.05
60
Frequency
59.95
59.9
59.85
59.8
3. Operating models (cont.d)
• Generation (cont.d)
– Frequency control. Dispatch of power generation held as
“reliability reserve” (cont.d)
• Means. Deployment of “reliability reserve” power generation to
manage unscheduled changes.
– Instantaneous governor response (within seconds): socialized
responsibility because all operating generators are equipped to
“respond” to any frequency change in order to maintain frequency.
• The most expensive reserve
• The most difficult to measure and require
– Regulation & AGC (automatic generation control) by more slowly
deployable reserve (within ten minutes) that is deployed to free-up the
governor response for response to the next frequency change.
11
The value of resources lies not just in the amount of energy but also in
how readily the energy is available to counter sudden frequency error.
Resources
stacked by value
Frequency
Response
Regulation
Operating Reserves
Load Following Following
Energy Market Energy
Capacity
Response Time
in order of quickness
\\
Seconds
A Few to Several Minutes
10 to 15 Minutes
30 Minutes
Market Interval – One Hour
Response Not Defined
Adapted from Energy Mark, Inc.
Rapidly Stopping a Frequency Drop
All generators rapidly slow down when generation is suddenly lost while inertia,
shared governor response, and load-response counter and arrest the slowdown
within seconds.
40
60
Seconds
59.925
Hz
(Shared)
Rapid Response
1
60
59.925
AGC & Regulation (including by the party responsible for the power loss)
10
Minutes
Hz
AGC & Regulation Gradually Restore Frequency
Some generators subsequently gradually provide additional excess power to
replace the original power loss, while all shared governor response is gradually
withdrawn in readiness for the next sudden power loss.
Source: “Author’s analysis and Robert W. Cummings “Overview Frequency Response Initiative”, North American Electric Reliability Corp.
(Princeton, NJ) 2010. http://www.spp.org/publications/NERC%20Frequency%20Response%20Initiative%20Overview.pdf
Perverse Governor Response
40.8
60.2
40.6
60.1
60
40.4
40.2
59.9
Frequency
59.8
40
59.7
39.8
59.6
39.6
59.5
Poplar Hills MW Output
39.4
39.2
8:24:00
59.4
8:31:12
8:38:24
8:45:36
8:52:48
9:00:00
9:07:12
POPLAR H.A790S POPLAR HILL GEN .AV
9:14:24
9:21:36
Freq
9:28:48
59.3
9:36:00
3. Operating models (cont.d)
• Generation (cont.d)
– Frequency control. Dispatch of power generation held as
“reliability reserve” (cont.d)
• US Measure/standard:
– Instantaneous response:
• based on a self-measure of responsiveness
• included as an obligation in the non-instantaneous response
measure
• Result:
• --Cheaper, non-instantaneous response is being used to meet the
• instantaneous response obligation
• --frequency response deterioration in North America (SEE NEXT
• SLIDES)
• --2003 Northeast blackout because the instantaneous response
• obligation was not strictly met
15
3. Operating models (cont.d)
• Generation (cont.d)
– Frequency control. Dispatch of power generation held as
“reliability reserve” (cont.d)
• US Measure/standard (cont.d):
– Instantaneous response (cont.d):
• Result (cont.d):
• --Introduction of more wind & solar power is further deteriorating
• frequency stability
» Add to variability rather than add to system responsiveness
» They displace fossil generation that could have provided response
capability.
» Add to slower acting variability that requires a large amount of slower-acting
“regulation” reserve that must in turn be backed by a proportional amount of
frequency-responsive reserve for when the regulation reserve runs out.
» Newer wind turbines can be programmed to provide inertial response that
only slows frequency deterioration, but not governor response which stops
and begins reversal of frequency deterioration.
» Wind’s capacity utilization factor of 5-30% would require a back-down
reserve margin of 17-140% to provide a rapid-response reserve comparable
to the 5-7% reserve margin of traditional fossil generators.
• --A measure is currently being developed but will take at least
16 2
• years before implemented
Deteriorating Eastern Interconnection Frequency Response
4,000
3,500
*
3,000
MW / 0.01 Hz
2,500
2,000
1,500
1,000
500
* 1999 Data Interpolated
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Source:
J.
Ingleson
E.
“Tracking
Eastern
Interconnection
Frequency
Governing
Characteristic”,
IEEE
Power
& Energy
Year
Source:
J. Ingleson&&July
E. Allen,
Allen,
"Tracking
thethe
Eastern
Interconnection
Frequency
Governing
Characteristic"
to be presented
at 2010
IEEE
PES
Society,
Minneapolis,
26, 2010.
MW/0.1 Hz
WECC Frequency Response
1600
1550
1500
1450
1400
1350
1300
1250
1200
1150
1100
1998
1999
2000
Year
2001
2002
20 NJ)
Source: Robert W. Cummings “Overview Frequency Response Initiative”, North American Electric Reliability Corp. (Princeton,
2010, slide 13. Slide 30 of http://ewh.ieee.org/cmte/pes/etcc/B_Cummings_Latest_Developments_on_NERC_Standards.pdf
Asleep at the Switch.
Robbing Peter to Pay Paul.
Deadbanding of Governors Worsens the Frequency Volatility/Risk on an Interconnection
Deadbanding All the Governors on an Interconnection Fattens the Tails of the Probability Distribution
of Frequency Error by at least a 1/2 Standard Deviation Worth of Extra Probability Mass
Near Normal Distribution
Flat-top Near Normal Distribution stretched by ½ SD of
0.0239
Within the Deadband, Frequency
Error is Distributed Uniformly with
No Central Tendency
0.0209
Count as a Share of 1
0.0179
0.0149
Deadbanding Transfers Central
Probability Mass from the Old
Distribution to Tail Mass of the
New Distribution
0.0119
0.0089
Deadbanding Transfers Central
Probability Mass from the Old
Distribution to Tail Mass of the
New Distribution
0.0059
0.0029
Frequency Error (Hz)
0.250
0.200
0.150
0.100
0.050
0.000
-0.050
-0.100
-0.150
-0.200
-0.250
-0.0001
Source: Author’s analysis and H.F. Illian & S.L. Niemeyer, “Integrating Variable Renewable Energy Resources into the Smart Grid”, Carnegie Mellon University Transmission Conference, Pittsburgh, March 10, 2009.
http://www.ece.cmu.edu/~electricityconference/2009/2009%20CMU%20Smart%20Grids%20Conf%20Disk/P
resentations/Day%201/Session%201/P11_H%20Illian_Integrating%20Renewable%20Resources.pdf
Governor response is
proportional at the deadband reaching 5% at 3 Hz
deviation
Frequency
Grid
Deviation Frequency
Hz
Hz
-0.04000
-0.03900
-0.03800
-0.03700
-0.03600
-0.03500
-0.03400
-0.03300
-0.03200
-0.03100
-0.03000
-0.02900
-0.02800
-0.02700
-0.02600
-0.02500
-0.02400
-0.02300
-0.02200
-0.02100
-0.02000
-0.01900
-0.01800
-0.01700
-0.01600
59.96000
59.96100
59.96200
59.96300
59.96400
59.96500
59.96600
59.96700
59.96800
59.96900
59.97000
59.97100
59.97200
59.97300
59.97400
59.97500
59.97600
59.97700
59.97800
59.97900
59.98000
59.98100
59.98200
59.98300
59.98400
Frequency
Response
MW
ERCOT
Frequency
Grid
Deviation Frequency
Hz
Hz
Droop %
4.69287
8.52357%
4.49175
8.68258%
4.29064
8.85650%
4.08952
9.04752%
3.88840
9.25830%
3.68728
9.49208%
3.48617
9.75283%
3.28505 10.04551%
3.08393 10.37636%
2.88281 10.75338%
2.68170 11.18694%
2.48058 11.69081%
2.27946 12.28359%
2.07835 12.99110%
1.87723 13.85020%
1.67611 14.91548%
1.47499 16.27125%
1.27388 18.05512%
1.07276 20.50786%
0.87164 24.09245%
0.67052 29.82737%
0.46941 40.47654%
0.26829 67.09147%
0.06717 100.00000%
0.00000 100.00000%
0.01666 Hz Dead-Band
Governor response
“Steps” to the 5%
droop curve at the
dead-band
Step response at
the dead band,
absolutely do not
want.
Proportional
implementation
frominside the 36
mHz dead band,
absolutely what
we want. It is
linear from thea
16 mHz dead band
to +/-3 Hz (but
droop is nonlinear: does this
matter?). Yes,
linear/”proportion
al” by 2011.2
MW/0.1Hz.
Dead-band
-0.04000
-0.03900
-0.03800
-0.03700
-0.03600
-0.03500
-0.03400
-0.03300
-0.03200
-0.03100
-0.03000
-0.02900
-0.02800
-0.02700
-0.02600
-0.02500
-0.02400
-0.02300
-0.02200
-0.02100
-0.02000
-0.01900
-0.01800
-0.01700
-0.01600
59.96000
59.96100
59.96200
59.96300
59.96400
59.96500
59.96600
59.96700
59.96800
59.96900
59.97000
59.97100
59.97200
59.97300
59.97400
59.97500
59.97600
59.97700
59.97800
59.97900
59.98000
59.98100
59.98200
59.98300
59.98400
Frequency
Response
MW
8.00000
7.80000
7.60000
7.40000
7.20000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
Droop %
5.00000%
5.00000%
5.00000%
5.00000%
5.00000%
Dead-band
100.00000%
100.00000%
100.00000%
100.00000%
100.00000%
100.00000%
100.00000%
100.00000%
100.00000%
100.00000%
Do you call this
100.00000%
response “continuous
100.00000%
but non-linear change
100.00000%
100.00000%
inside the dead band?
100.00000%
No. It’s
100.00000%
“discontinuous”.
100.00000%
100.00000%
100.00000%
100.00000%
0.036 Hz Dead-Band
600 MW Steam Turbine 5% Droop Setting
ERCOT
±16 mHz deadband
MW Response
Responsiveness=Slope=-20 MW/0.1Hz
Droop: linear (5%)
Responsiveness=Slope=-20.112 MW/0.1Hz
Droop: geometrically decreasing (to 5% at ±3Hz)
MW Response
±36 mHz deadband
600
-2 DHz
-1 DHz
1 DHz
2 DHz
0
-600
-3 DHz
0 DHz
3 DHz
3. Operating models (cont.d)
• Generation (cont.d)
– Frequency control. Dispatch of power generation held as
“reliability reserve” (cont.d)
• US Measure/standard: (cont.d)
– Non-instantaneous response: CPS1 Control Performance Standard.
(SEE EQUATION & GRAPH)
• Measures:
• --a statistical average over time
• --a combination of (“covariance” between) system frequency
• deviation and individual deviation.
• ----When the system deviates very much, the individual member is
•
allowed to deviate very little
• ----When the system deviates very little, the individual member is
•
allowed to deviate very much
• The deviation limits can be statistically determined (SEE GRAPH)
• --by the US standard of a once-in-ten-years probability of a major
• blackout event. (Economies have experienced recessions at
• approximately the same rate in the past century.)
24
• --by a database of scanned frequency and tie-line error
NERC ' s _ CONTROL _ PERFORMANC E _ MEASURE _ FOR _ BALANCING _ AUTHORITY _ i


1
T i  10Bi DF t
 10Bi 2
DF t 


525,600 tyear
 10B I
 10B I
Control _ Performanc e _ S tan dard _ for _ Interconne ction _ I :
1
 525,600 
iI
tyear
T
i

 10Bi DF t
B
DF t   i  2
 10B I
iI B I


  T i  10DF t  Bi 
Bi

1
iI
 iI
 DF  iI
2
t

525,600 tyear
 10B I
BI
1
2
DF t   2

525,600 tyear
 : t arg et _ lim it _ on _ average _ frequency _ deviation
DF t : 1  min ute  average _ frequency _ deviation _ at _ min ute _ t
T i : 1  min ute  average _ Tie  line _ Error _ of _ Balancing _ Authority _ i. Ti  0
iI
Bi : MW / 0.1Hz _" bias " _ of _ Balancing _ Authority _ i' s _ generation _ fleet
B I : MW / 0.1Hz _" bias " _ of _ Interconne ction _ I' s _ generation _ fleet . Bi  BI
I  i i _ are _ synchronou sly _ int erconnecte d _ to _ each _ other 
iI
ACE i : Area _ Control _ Error _ of _ Balancing _ Authority _ i
ACE i  T i  10Bi DF t
 10Bi DF t : the _ shared _ obligation _ to _ provide _ ins tan tan eous _ governor
__________ response _ to _ prevent _ ins tan tan eous _ frequency _ deviations _ from _ getting _ l25
arg er
525,600 : number _ of _ min utes _ in _ a _ year
NERC’s Control Performance Standard
p : Instantaneous Approximate CPS1
Probability On average over the past year:
or p
 : Annual standard
+ MW,
: in same direction as D F
deviation of D F
+
RMS
2
"No inadvertent allowed
Limit :    + m 2 DF 
in the direction of
m D F  : Year's Mean of D F
Frequency error when
DF : 1-minute average of
"
DF  
Frequency error

+
Bi < 0: Control area i's bias
-
-50
50
 10 Bi D F
DF
+(mHz)
10 B i D F
: Control area
i's maximum allowed 1-minute average tie-line
error (plus response obligation) in direction of the frequency error:
:
Ti  10Bi    DF 
 DF

One-year probability density limit on 1-minute
averages of frequency error, adjusted for deviation of
the mean from 0
Reducing the Standard Deviation Bandwidth to Reduce the Area/Probability under the Tails of
the Distribution
NormalDistribution4SD
NormalDistribution
0.0239
0.0209
0.0179
0.0119
0.0089
0.0059
0.0029
FrequencyError(Hz)
0.250
0.200
0.150
0.100
0.050
0.000
-0.050
-0.100
-0.150
-0.200
-0.0001
-0.250
Probability
0.0149
3. Operating models (cont.d)
• Generation (cont.d)
– Frequency control. Dispatch of power generation held as
“reliability reserve” (cont.d)
• Deterioration in North American frequency response performance
– Specifically
• upward drift in frequency to near the control limits (SEE NEXT
SLIDE)
• persistent imbalance accumulations by system participants
– Due to no “price” for unscheduled power
• no cost or penalty assessment to the causers of imbalance (users of
somebody else’s reliability reserve)
• no reward to the remediators of imbalance (holders of reliability
reserve).
– Result
• Cost is socialized in fixed transmission fees paid by consumers
• Imbalance increases because it is free power to the entity who
produces it or consumes it.
28
in The New York Times, August 20, 2003:
10
Hz of DF h
Frequency Response Measure for BA i: DMWi/Df.
DMWi is response provided by i.
31
Decomposition of Near-Normal Distribution of Frequency Error
into Normal Distribution of Normal Errors, & Back-to-Back Chi-Square Distribution of Events.
Back-to-Back Chi-Square Distributions
NormalDistribution
0.0239
0.0209
0.0179
0.0119
0.0089
0.0059
0.0029
FrequencyError(Hz)
0.250
0.200
0.150
0.100
0.050
0.000
-0.050
-0.100
-0.150
-0.200
-0.0001
-0.250
Probability
0.0149
Distribution/Decomposition of Frequency Response Performance/Responsibility
33
4. Challenges in grid configuration
and management
• Radial versus networked. Active power versus
reactive power
– A radial grid consists of remote large generation such as
coal, hydro, and nuclear
– A networked grid is a mix of
• remote generation to take advantage of trade, and
• local, typically gas-fired generation to provide
– “peaking” plants to serve infrequent peak load at low capital cost at a
high enough electricity price to pay the capital cost (SEE NEXT SLIDE)
– local reliability reserve to deploy to
• meet local disturbances/contingencies without
• --disturbing the systemwide powerflow by deploying remote reserve
• generation, and thereby
• --making a local disturbance rapidly spread to collapse a wide area
• of the power system and
• --adding a second possible contingency (loss of transmission) to a
• single contingency (loss of generation accessed by that 34
• transmission) (SEE SLIDE)
Electric systems based on marginal-cost pricing use low-capital-cost gas turbines
to most efficiently meet peak load. High natural gas prices just lower the “capacity factor”
which is how long the plant can operate before the coal plant becomes cheaper.
High gas prices just rotate the GT
line upward around the pivot point
of intersection with the price axis
30 %
Peak, shortduration
load served
by gas
turbines
35
Load
Local Balancing
May Require Less
Transmission
Centralized Balancing
May Require More
Transmission
G
G
L
L
RISO
Rlocal
G
G
Sudden local generator loss
Rlocal
Local Balancing
Authority
deploys local
responsive
reserve
Sudden local generator loss
Congested transmission
L
ISO deploys
responsive reserve
from big central
source
L
RISO
G
Rlocal
Local responsive
reserve still
available to the
system
RISO
Sudden remote generator loss
G
G
Without congesting transmission
L
Build transmission
L
L
4. Challenges in grid configuration
and management (cont.d)
• Radial versus networked. Active power versus
reactive power (cont.d)
– A networked grid is a mix of (cont.d)
• local, typically gas-fired generation to provide (cont.d)
– local reliability reserve to deploy to (cont.d)
• provide a source of “reactive” power to prevent reduction of
transmission capacity due to the import of “active” power.
• --Reactive power supports voltage and is determined by the phase• shift between alternating voltage and alternating current. It
• ----can travel only a short distance (150 km)
• ----affects the electrical capacity of transmission lines, and
• ----must be provided locally by capacitors, synchronous condensers,
•
generation or extra unused transmission capacity.
• --Active power is scheduled energy.
• ----Too much long-distance power flowing from the Midwest to the
•
Northeast on a grid network not designed for long-distance
•
power flow was a factor in the US Northeast Blackout of 2003
• ----This fact was expressly omitted in the final DOE blackout report
37
•
on the basis that long-term power transactions are economics,
•
not reliability.
4. Challenges in grid configuration
and management (cont.d)
• Integrating the natural-gas pipeline network with the
electricity grid
– A robust open-access natural-gas pipeline grid
• stabilizes an electricity grid by providing the natural gas to fire local
gas-fired power plants
• dramatically reduces coal-mining accidents by enabling the sale and
distribution of all coal-bed methane gas before coal mines are dug.
– The presence or not of local gas-fired electric power affects
the configuration of the electric grid providing remote power
– A gas pipeline grid and the electric transmission grid are
complements to each other, not competitors of each other
38
4. Challenges in grid configuration
and management (cont.d)
• Interconnection or isolation
– US transmission interconnections between integrated
utilities, and eventually control areas
• were originally entirely reliability reserve (begun in the late 1920s),
then
• became used for economic transactions (after WWII). When the
concepts of economics and reliability were separated, an unused
portion of capacity was assigned for reliability/contingencies
– Advantages & disadvantages of interconnection
• Interconnected power systems
– benefit from the
• economics of long-distance power trade, and
• the reliability benefit of frequency support among the interconnected
regions, but
– suffer from vulnerability that a local disturbance can spread to become a
collapse of an entire wide-area system
39
4. Challenges in grid configuration
and management (cont.d)
• Interconnection or isolation (cont.d)
– Advantages & disadvantages of interconnection (cont.d)
• Non interconnected systems
– are completely robust to disturbances from neighbors
– do not benefit from gains from trade between systems
• The world financial and economic system is experiencing this
– China’s banking system was
• largely immune from the financial crisis because not integrated into
the global financial system, but
• did not benefit from the previous advantages of financial integration
– China’s economy is
• affected by the economic recession because integrated into the
world trade system, and
• threatened by protectionism by other countries to substitute their
increased national production/jobs for imports/jobs from China.
• DC ties provide
– the economic advantages of interconnection, but
40
– not the reliability advantages or disadvantages of interconnection
4. Challenges in grid configuration
and management (cont.d)
• Congestion management
– Transmission congestion is efficiently managed only on an
economic basis through market-based
• long-term transmission contracts/rights and
• spot locational marginal pricing of purchased power
– Transmission congestion pricing provides an objective
economic basis for eliminating or not the congestion
bottleneck by building more transmission or building more
generation on the expensive side of the constraint
– For an efficient power grid, price-based congestion
management applies to railroad transportation, a key means
of transporting coal to power plants.
41
4. Challenges in grid configuration
and management (cont.d)
• Centralized versus decentralized control
– Transmission congestion management is best centralized
into a single control-room/area because actions have a
systemwide effect on powerflow and locational prices
– Frequency control is best decentralized because the control
error by a single central control center is greater than the
combined errors of multiple control-centers which cancel
each other out
• This was evident when the ERCOT (Electric Reliability Council of
Texas) centralized frequency control into a single control center and
frequency performance deteriorated
• There is an unfortunate trend in the US to centralize frequency
control into ever larger ISOs (Independent System Operators) which
operate centralized spot markets for pricing congestion. The 2003
Northeast Blackout originated in the hastily-organized, largest and
newest of those, the Midwest ISO.
42
4. Challenges in grid configuration
and management (cont.d)
• Adequate reserve generation
– “Economic” reserve can be handled by a robust market
whose participants use their own market-based planning
models
– Reliability reserve is driven by a system “requirement”
enforceable by a penalty since reliability is a “public good”
like clean air. The requirement can be
• a direct reserve requirement not directly relatable to
– operating performance, and
– causation of cost
• or a(n operating) performance requirement
– whereby the entity decides the level of reserves/risk to bear in order to
perform within the targeted performance requirement, and
– can be directly related to cost causation.
43
4. Challenges in grid configuration
and management (cont.d)
• Market pricing to address the environment
– Market pricing of energy
• curtails energy consumption when prices are high because demand
is too great
• increases energy consumption when prices are low because the
economy is depressed
• is called Demand Response, or Demand-Side Management
– Global Warming and renewables have displaced other
environmental concerns, such as with hydro and nuclear
– The reliability cost of the frequency instability caused by
wind and solar
• is not being included in their economic cost
• needs to be measured and allocated directly to the specific wind and
solar generators and paid to the providers of frequency support
• instantaneous systemwide governor response cannot be selfprovided economically by a wind or solar renewable generator.44
4. Challenges in grid configuration
and management (cont.d)
• Market pricing to address the environment
(cont.d)
– Global warming and renewables are likely to be
ignored if a sustained global recession takes hold.
A likely at least 5 % drop in global GDP for at least
a year meets the global warming reduction goal of 1
% GDP reduction for the next 5 years!
45
4. Challenges in grid configuration
and management (cont.d)
• Smart Grid does not by itself solve the hardest grid
configuration & management challenges. Smart Grid
– provides uiseful tools like
• FACTs devices to route power to avoid congestion
• Frequency responsive hot-water heaters that nevertheless cannot
provide instantaneous frequency response
• Batteries to drain and discharge variation excesses and deficits
caused by wind power.
– does help solve the challenge of limited US grid expansion
– does not address cost causation and allocation for these
devices, nor least cost.
– should not be used to subsidize and socialize the costs of
devices and to override attempts to market price and
allocate those costs. For example,
• instead of congestion cost being borne by the parties causing it, and
• without comparing the cost of the FACTS device with the cost of
other remedies, such as increasing transmission capacity or adding
46
generation.
5. Challenges for China
• Greater efficiency is needed in the resources sector of
the economy, including electric power (SEE NEXT
SLIDE)
• Greater transparency is needed in the models used to
plan and operate the grid, to
– enable providers to propose hardware and software
solutions and not just respond to requests from central grid
management
– enable market participants to better forecast, plan and
manage risk
47
48
http://ihome.ust.hk/~socholz/China-productivity-measures-web-22July06.pdf
5. Challenges for China (cont.d)
• End below-cost and below-market price regulation
– Below world-commodity-market-cost based pricing, such as
for electricity, coal and oil-products, prompts excess Chinese
consumption that
• pushes world prices higher and only hurts China because China has
now become a net coal importer, not just oil importer (SEE NEXT
SLIDES)
• creates unnecessary environmental problems.
– Consequently, China imposes administrative demand
reduction measures to compensate for the adverse
environmental effect of too-low prices, when the simplest
solution is
• eliminate the below-market, below-cost pricing
• subsidize poor people directly by giving them cash not related to
electricity usage. They will consume less electricity and use the cash
for something else.
– Begin demand-side pricing/bidding in the electric power49
market, now that world energy prices were lower for a while.
China's Coal Imports and Exports, 2002-2007
Source: National Bureau of Statistics
http://www.researchinchina.com/report/UploadFiles_8547/200708/20070802151002331.gif
50
Source: International Energy Agency World Energy Outlook 2007
51
Coal Production
Peak production in
2025
According to the Energy Watch analysis, world coal production will peak in around 2025. In that case
output would undershoot official forecasts from the International Energy Agency’s World Energy
Outlook (WEO) by a substantial margin. Source: (1) Energy Watch Group, of scientists led by the
German renewable energy consultancy Ludwig Bölkow Systemtechnik (LBST) , & (2) Energy Data
Associates, Dorset, UK
52
http://www.energybulletin.net/39236.html
5. Challenges for China (cont.d)
• Build an interconnected national natural gas pipeline
grid, China’s only missing piece of world-class
infrastructure (A good economic stimulus
infrastructure project. Planning of the electric
transmission system and the gas pipeline system
should take each other into account and not fight each
other. SEE NEXT SLIDES)
– to provide the local power generation needed to stabilize the
radial grid from outage, especially if the grid is elevated to
1000 kV transmission, by bringing
• Western gas to the East and
• Eastern gasified LNG to inward areas
– to provide an energy delivery system that is immune to
winter icing
– to provide environmentally friendly gas power
– to increase the amount of peaking generation on the system
• to improve the system economics of too much base-load generation
(coal, nuclear and hydro) SEE SLIDES
• to reduce the use of peak-load shedding corresponding to too 53
big a
share of base-loaded generation in the fleet
Thermal Base
3000MW
2500MW
1800MW
7200MW
10000MW
Hydro Power Base
9000MW
2000MW
3000MW
AC
DC
Regional Grids Interconnection in 2005
54
Thermal Base
3000MW
2500MW
1800MW
7200MW
10000MW
Hydro Power Base
9000MW
2000MW
3000MW
Possible International
connection
AC
DC
Regional Grids Interconnection in 2010
55
Thermal Base
3000MW
2500MW
1800MW
7200MW
10000MW
Hydro Power Base
9000MW
2000MW
3000MW
Possible International
connection
AC
DC
Regional Grids Interconnection in 2015-2020
56
Existing and planned,
North & South China,
but excluding
CNOOC’s proposed
Coastal Grid
0
300 公里
Km
57
Existing and planned, North & South China,
plus CNOOC’s proposed Coastal Grid
SOURCE http://www.iea.org/textbase/work/2005/LNGGasMarkets/session_5/1_Yugao_Xu.pdf
58
Source: http://www.ieej.or.jp/aperc/final/ne.pdf
59
China’s natural-gas fired power generation capacity
expected at least to exceed nuclear and new energies,
and use 30-40 % of natural gas supply capacity of 100
BCF in 2010 and 200 BCF in 2020
gas-fired
Source: Investment in China’s Demanding and Deregulating Power Market, 60
Capgemini Consulting 2005.
SOURCE: http://www.ieej.or.jp/aperc/pdf/GRID_COMBINED_DRAFT.pdf
61
62
SOURCE: http://www.ieej.or.jp/aperc/pdf/CHINA_COMBINED_DRAFT.pdf
63
SOURCE: http://www.ieej.or.jp/aperc/pdf/CHINA_COMBINED_DRAFT.pdf
5. Challenges for China (cont.d)
• Build an interconnected national natural gas pipeline
grid, China’s only missing piece of world-class
infrastructure (A good economic stimulus
infrastructure project. Planning of the electric
transmission system and the gas pipeline system
should take each other into account and not fight each
other.) cont.d
– to eliminate coal-mining fatalities by enabling all the coal-bed
methane gas to be removed from from mines for sale and
distribution to consumers. (SEE NEXT SLIDE)
– to protect areas like Guizhou from winter blackouts like
2007’s by enabling it to extract and distribute coal-bedmethane gas that
• enables mining abundant local coal to fuel abundant local coal-fired
power plants and end remote coal delivery interruptible by winter
icing conditions
• fuels sufficient local gas-fired reserve power generation deployed if
the transmission system collapses from icing, or during winter 64
peaking or during low rainfall/reservoir periods (SEE SLIDES)
http://www.worldcoal.org/assets_cm/files/PDF/coalmining.pdf
65
http://www.mapsofworld.com/business/industries/coal-energy/china_coal_deposits.jpg
66
http://www.american.com/graphics/2007/may-june-2007/coal-in-china/China%20Map.JPG
67
68
http://www.platts.com/Coal/Resources/News%20Features/ctl/images/chinamap.gif
5. Challenges for China (cont.d)
• Build an interconnected national natural gas pipeline
grid, China’s only missing piece of world-class
infrastructure (A good economic stimulus
infrastructure project. Planning of the electric
transmission system and the gas pipeline system
should take each other into account and not fight each
other) cont.d
– The current NPC will vote the new energy law that will make
the gas pipeline grid like the electric transmission grid by
• opening access to gas pipelines to any producer or consumer under
a single regulated tariff,
• by separating the pipeline operation function from the production and
sales function
• Develop congestion pricing, including for railways to
enable contract and supply certainty during times of
congestion, such as coal delivery during winter. The
2007 winter blackout occurred partly because remote
coal delivery to coal-fired power plants was interrupted
69
by congestion.
Appendix
70
North American Synchro Phasor
Initiative
• Funded by DOE & NERC
• At first stage: providing better measurement of
–
–
–
–
frequency transients
excessive angular separation between PMUs
voltage drop
oscillations: often precursors seen minutes or hours before
a major disturbance
– MW flows
– size & location of large generation trips
– & other signs of grid stress
• by a Phasor Measurement Unit (PMU): high speed
– 30 samples per second
– versus 1 sample per 4 seconds
71
•
North American Synchro Phasor
Initiative
(cont.d)
In order to
– provide
• wide-area monitoring. Now (see slides) achieved in the
– Eastern Interconnection by Real Time Dynamic Monitoring System from
central data maintained by Tennessee Valley Authority
– Western Interconnection by Wide Area Monitoring System (WAMS)
• forensic analysis of grid disturbances
– to trigger
• corrective action ahead of time (see slides), not just
• post mortem analysis
• Data
– is time-stamped to a common time reference for the entire
interconnection, but
– Format must be converted to conform across the
interconnection
• Problem: PMUs are not “plug N play”
– Not all the same output
– No cookbooks: much engineering & IT time to set up
72
http://www.naspi.org
73
Why Phasors?
• Wide-Area and Sub-SCADA Visibility
• Time Synchronization Allows us to see Dynamics not
Visible in SCADA Environment
• Analysis of Major Events Typically Show Angular or
Dynamic Warning Signs Minutes to Hours
Beforehand
Relative Phase Angle
August 14 Angular Separation
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
-140
-150
-160
-170
Normal Angle ~ -25º
15:05:00 15:32:00 15:44:00 15:51:00 16:05:00 16:06:01 16:09:05 16:10:38
Time (EDT)
Reference:
Browns Ferry
Source: www.nerc.com
74
Cleveland
West MI
30min plot: 9/18/2007 MRO Event
Source: Virginia Tech FNet Data
75
Fill the Gaps
76
Current Dashboard
CA Independent System Operator (CAISO)
Real Time Dynamics Monitoring System (RTDMS)
77
Small Signal Monitoring
Observable Mode Clusters
Spectral Monitoring of Select Signal
Poorly Damped Mode
Mode Frequency (Hz)
Alarm Threshold
<3% damping
Damping Ratio (%)
78
Download this presentation:
• In English at
http://www.blohm.cnc.net/SmartGrid.ppt
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http://www.blohm.cnc.net/SmartGridHanyu.ppt
Note: .ppt file name is case sensitive
79