Download ppt presentation - Missouri S&T Power Group

New Challenges in High Penetration
Renewable Energy Sources
Eduard Muljadi
National Renewable Energy
Laboratory
Golden CO
[email protected]
Missouri S&T University
October 12, 2009
Rolla, MO
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Conventional vs.
Wind Power Plant
Load
Load
Other Conv.
Generator
POI or
connection
to the grid
Interconnection
Transmission Line
GSU
Xfmr
Large
Synchronous
Generator
Collector System
Station
Prime
Mover
Research needs for wind plant:
• Collector system optimization
• Reactive power management
• Voltage regulation at POI and each turbine
• AC vs. DC; OH vs. UG; offshore vs. in land collector systems.
• Predictive maintenance.
• Wind plant model vs. WTG model.
Individual WTGs
Feeders and Laterals (overhead
and/or underground)
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Power Generation
Conventional Power Plant
• Single or multiple large (100 MW) generators.
• Prime mover: steam, combustion engine – non-renewable
fuel affected by fuel cost, politics, and pollution restrictions.
• Controllability: adjustable up to max limit and down to min
limit.
• Predictability: preplanned generation based on load
forecasting, influenced by human operation based on
optimum operation (scheduled operation).
• Located relatively close to the load center.
• Generator: synchronous generator
• Fixed speed – no slip: flux is controlled via exciter winding.
Flux and rotor rotate synchronously.
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Power Generation
•
•
•
•
•
•
•
Wind Power Plant
Many (hundreds) of wind turbines (1 MW – 5 MW each)
Prime mover: wind (wind turbine) –renewable (free, natural,
pollution free)
Controllability: curtailment
Predictability: wind variability based on wind forecasting,
influenced more by nature (wind) than human, based on
maximizing energy production (unscheduled operation).
Located at wind resource, it may be far from the load center.
Generator: Four different types (fixed speed, variable slip,
variable speed, full converter) – non synchronous generation
Type 3 & 4: variable speed with flux oriented controller (FOC)
via power converter. Rotor does not have to rotate
synchronously.
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Power Generation
Conventional vs Wind Power Plant
•
Single or multiple large (100 MW)
generators.
•
Many (hundreds) of wind turbines (1 MW – 5
MW each)
•
Prime mover: steam, combustion engine
– non-renewable fuel affected by fuel
cost, politics, and pollution restrictions.
•
Prime mover: wind (wind turbine) –renewable
(free, natural, pollution free)
•
Controllability: adjustable up to max limit
and down to min limit.
•
Controllability: curtailment
•
Predictability: preplanned generation
based on load forecasting, influenced by
human operation based on optimum
operation (scheduled operation).
•
Predictability: wind variability based on wind
forecasting, influenced more by nature (wind)
than human, based on maximizing energy
production (unscheduled operation).
•
Located relatively close to the load
center.
•
Located at wind resource, it may be far from
the load center.
•
Generator: synchronous generator
•
Generator: Four different types (fixed speed,
variable slip, variable speed, full converter) –
non synchronous generation
•
Fixed speed – no slip: flux is controlled
via exciter winding. Flux and rotor rotate
synchronously.
•
Type 3 & 4: variable speed with flux oriented
controller (FOC) via power converter. Rotor
does not have to rotate synchronously.
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Power Generation
Types of Wind Turbine Generator
Four basic topologies based on grid interface:
– Type 1 – conventional induction generator
– Type 2 – wound-rotor induction generator with variable rotor
resistance
– Type 3 – doubly-fed induction generator
– Type 4 – full converter interface
Type 1
Type 2
Type 3
Pla nt
Fee ders
Plant
Feeders
gene rator
generator
PF control
capacitor s
Slip power
as heat loss
Plant
Feeders
generator
ac
to
dc
PF control
capacitor s
Type 4
Plant
Feeders
generator
ac
to
dc
dc
to
ac
ac
to
dc
dc
to
ac
full power
partial power
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Power Generation
Types of Wind Turbine Generator
Research needs:
– Needs a light weight, high efficiency, high power, low rpm, direct drive
generator and the corresponding power converter, suitable for harsh
environment (offshore).
– Smarter control strategies to reduce the loads, increase energy yield, and
capable of riding through voltage transients and producing high power quality
under normal conditions.
– New types of power converters: high power, high efficiency, and good grid
interface capability.
Type 1
Type 2
Type 3
Pla nt
Fee ders
Plant
Feeders
gene rator
generator
PF control
capacitor s
Slip power
as heat loss
Plant
Feeders
generator
ac
to
dc
PF control
capacitor s
Type 4
Plant
Feeders
generator
ac
to
dc
dc
to
ac
ac
to
dc
dc
to
ac
full power
partial power
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Real and Reactive Power Balance
(to keep frequency and voltage constant)
Adjustable
Loads
Base
Loads
Inductive
Induction
Variable
Load
Motors/Generators
Line
Loads
Power Losses Inductance
Freq UP
Voltage UP
Static
Real Power
Storage
Reactive Power
Compensation
Freq Down
Voltage Down
Base
Line
Reserves
Generators Adjustable
Capacitance
Variable
Switched
Generators Generators
Capacitors
(conventional
(RE)
Gen, RE)
Synchronous
Generators/
Condensers
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Output Variability
Wind
Power
Generator
storage
VAR
Compensation
to help
regulate voltage
(Load
Center)
Other
generators
Low
Wind
Penetration
Level
Output power due
to
wind variability
Power delivered
unaffected by
wind variability
Output
power to
compensate
wind
variability
time
Research needs:
• Reactive power management
• Fast acting generation reserves
• Aggregation impacts on power smoothing
• Ramp up/down impacts
• Storage
VR
• Forecast
time
Voltage and Freq
unaffected by
wind variability
time
time
Output power due to
wind variability
High
Wind
Penetration
Level
Output power
to
compensate
wind
variability
time
Other
generators
Power delivered can be
affected by
wind variability
time
Voltage and Freq can be
affected by
wind variability
time
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
time
Transmission
Constraints
Wind
Power
Generator
Thermal Limit
(thin wire)
Storage
Wind
Power
Generator
(Load
Center)
Storage
Storage
(Energy Time
Shifter)
Stability Limit
(high impedance
long distance
weak-grid)
Research needs:
• Short term storage – stability improvement.
• Long term storage – economic/peak-shaving.
• Large-scale transmission optimized planning.
• HV Power Electronics (FACTS devices).
• Smart Grid, DSM, Deferrable Load, LAARS,
PHEV
• Forecast
Output power
to the load
Stored power
in the storage
Output
power
Powered by the plant Powered by the storage
time
time
time
Output power due to
wind variability
No-Storage,
Curtailment
(Energy Wasted)
Output
power
curtailed
Curtailment
time
time
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Nature of Load
Wind plant can only regulate
down (curtailment).
Generation following/scheduling
is based on wind forecast.
Research needs:
• Aggregation of ACE control
• Reserve sharing among balancing
areas
• Load Acting as Resource (ERCOT)
• Improve accuracy of wind forecast
• Look ahead control strategy.
Spinning Reserves
Spinning/Non Spinning Reserves
Sub-hour scheduling
Economic Dispatch
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Wind Power Plant
Output Data
Annual Hourly Average
Summer Peaking
Peak
Shift
Spring Peaking
Midwest Region
California Region
Research needs:
Adapt the characteristics the load (DSM) to the local source
Understand the regional behavior of wind pattern and other RE Sources.
Multiple types of RE sources in parallel mode.
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Matching
Wind and Load
Possible shift by Demand Side Management
Research Needs:
• Demand Side Management
• Power and information flow (in the same wire or
wireless)
• Hybrid appliances (gas/electric) activated by
electricity pricing.
• Price incentives for helping the grid maintain
frequency.
• Energy Storage
• Short term storage for stability of the power
system
• Distributed storage close to the load or end use
reduces round trip loss, encourages mass
production of storage at smaller sizes, thus
lowers the manufacturing cost.
• Buy low, sell high based on the signal LMP or
spot pricing.
Possible shift by Storage or
Parallel Operation with other RES
• Parallel Operation with other RES
• Generation profile from PV and CSP tends to
occur during the day when the price of electricity
is high. Thus, higher COE may be offset by the
LMP.
• Wind and sunlight are two different sources
with different time constants. Total output
variation may smooth out the total output.
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Price Triggered Load
Storage Activation
• Wind generation is intermittent and
varies during the day and it can cause
local congestions.
1:20PM
6:20PM
• Transmission congestions can lead to
unequal pricing and vulnerable power
system operations.
• Congestion triggers different in prices at
different sites throughout the day.
2:20PM
6:45PM
Research Needs:
• Economic incentive for V2G or G2V (as
energy commodity or spinning reserve)
based on transmitted pricing signal over
wired/wireless communication.
• Demand side management for customers
to get paid to turn on/off the loads to help
increasing stability margin.
• Smart devices, smart grid, wireless
communication will allow the automation
to take place during the day.
6:50PM
7:00PM
• Potential market for customers capable
of adjustable VAR production.
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Wind Power Plant
Operation
Normal Operation
Cumulative vs. Local Ramping Rates
One Day of Output Variation
Cumulative
Ramping Down
0.4 GW/Hr
Localized
Ramping Down
5.25 GW/Hr
Research needs:
• Fast acting reserve
• Coordination with nearby wind power plants
• Short-term energy storage to shape the ramp rates.
Research needs:
• Spinning or non spinning reserves
• Parallel operation with other RE sources
• Long-term energy storage to shift the
output and get a better price of electricity.
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Voltage Ride Through
(during transient events)
• Wind power plant should be able to stay online under transient faults/disturbances.
Voltage Ride Through
• The voltage should tolerate 0 p.u. for 15 msec
(9 cycles).
1.4
• The wind power plant should be able to
regulate the power factor between 0.95
leading/lagging.
1.2
Voltage (p.u.)
1
• The wind power plant should have a SCADA
system to allow remote access and monitoring.
0.8
0.6
Research Needs:
• Wind plant added value for VAR regulation
even when the wind plant is off line.
0.4
661
• Wide Area Monitoring, Protection and
Control.
661A
0.2
LVRT-WECC Prop.
HVRT-WECC Prop.
0
-1
0
1
2
3
4
• Wind plant coordination with surrounding
other plants.
Time (sec)
• WTG with integrated storage.
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Summary
• Power Quality (Voltage and Frequency) and Energy Management
• Voltage variations can be minimized by adjustable VAR compensation.
• Frequency variations can be minimized by fast acting spinning reserves and
storage (short term)
• Load-Wind matching can be improved by including other RE resources (CSP,
PV, Geo, Hydro, Bio), cleaner and cheaper conventional power plants, DSM,
and storage (long term: CAES, PHEV, Fuel Cell – H2, Battery, Flywheel).
• The forecast error can be minimized by shorter scheduling periods,
coordinated nationwide wind measurements, and better forecasting
methods.
• Transmission constraints and curtailment can be minimized by
improvements on the transmission lines (FACTS devices, Series/Parallel
Capacitors, additional lines, dynamic ratings, storage).
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Summary
• Phasor Measurement Unit (PMU) deployment allows the wind power
plant to be monitored more precisely during normal and transient
operation. The stability margin can be measured more accurately, and
remedial action scheme can be deployed at the correct time confidently,
thus blackout and outage can be prevented.
• Wide Area Monitoring, Protection, and Control (WAMPAC) can help
monitor the surrounding power system relative to the stability limit and
anticipate the next coordinated control action to protect the wind plant
ahead of potential/impending disturbances in the vicinity.
• Use of smart grid, modern control, high speed data communication, and
power system intelligence allow the system operates in autopilot and
reduces the burden on operators to manage normal operation but allows
special intervention in critical events.
• High penetration RE sources may force us to follow a new paradigm (AC
vs. DC, centralized vs. distributed, constant f vs. 60 Hz, synchronized vs.
floating/island networks, instant delivery vs. stored energy)
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC