September 12, 2013
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Transcript of September 12, 2013
Making Clean Local Energy Accessible Now September 12, 2013
Enhances System Reliability & EfficiencyDistributed Generation + Intelligent Grid (DG+IG)
Stephanie WangRegulatory Policy DirectorClean [email protected]
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Contents of DG+IG Presentation
• Overview of Grid Support Services
• DG+IG Balances Voltage
• DG+IG Balances Power & Frequency
• DG+IG Can Replace SONGS
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Overview of Grid Support Services
Service Summary
Voltage Control • Keep voltage within optimal range by injecting and absorbing reactive power.
Power Balancing
• Includes Regulation, Load Following/ Energy Imbalance, Operating Reserves.
• Balance real power supply and demand, keep frequency within optimal range.
Frequency Response
• Provide real power to respond to sudden losses of large generators or transmission lines.
Forecasting • Forecast power supply and demand.
Grid support services enable the reliable operation of electric grid systems.
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Overview of Grid Support Services
A number of studies, however, suggest that, as intermittent renewables become a larger presence in U.S. electricity generation, that 1% requirement will grow.
Balancing powersupply
and demand
Control voltage with reactive power
Source: Oak Ridge National Laboratory (2004)
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DG+IG Enhances System Efficiency & Reliability
• Overview of Grid Support Services
• DG+IG Balances Voltage
• DG+IG Balances Power & Frequency
• DG+IG Can Replace SONGS
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Distributed Advanced Inverters Balance Voltage
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 290.9
0.95
1
1.05
1.1
IG Corrects Overvoltage
IG Corrects Undervoltage
Source: Clean Coalition, 2013
Upper Limit
Lower Limit
Nominal Voltage
sec
per unit voltage
Advanced inverters locally absorb reactive power
Advanced inverters locally supply reactive power
“Reactive power supply is the key controller of voltage in alternating current (AC) power systems. Reactive power supplied locally could be a major player in improving system reliability as well as improving system efficiency.”
Oak Ridge National Laboratory (2008)
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DG+IG Core Solutions for Voltage Regulation
Solutions Benefits
Distributed Generation
• Provisions reactive power where it’s needed most for regulation• Avoids line losses• Reduces congestion of transmission and distribution lines
Advanced Inverters(paired with solar,
storage)
• Provisions distributed reactive power • Reacts automatically within fractions of a second (conventional
resources can take minutes to react)• Converts real power from the grid to reactive power 24/7/365• Oversized inverters can deliver reactive power without reducing DG
real power output• Ride-through voltage events, remain attached longer than
conventional spinning generators without harm• Modern inverters already have these advanced capabilities
Energy Storage(batteries, flywheel)
• Provisions both real and reactive power• Generally paired with advanced inverters
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Distributed Voltage Regulation – Location Matters
Efficient & reliable reactive power
(Advanced Inverters)
Benefits of distributed voltage regulation:• Enhances system reliability by providing
reactive power where needed• Improves system efficiency by avoiding
line losses and reducing congestion Oak Ridge National
Laboratory (2008)
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Distributed Voltage Regulation – Location Matters
“The old adage is that reactive power does not travel well.”
Oak Ridge National Laboratory (2008)
Source: Oak Ridge National Laboratory (2008)
T&D lines absorb 8-20x more reactive power than real power.
Prevent Blackouts:When a transmission path is lost, remaining lines are heavily loaded and losses are higher.
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Advanced Inverters Keep Voltage in Balance
• An inverter converts direct current (DC) to alternating current (AC) power.
• Advanced inverters from Germany to State of Georgia have been programmed to deliver reactive power.
• Proposed changes to IEEE 1547a and UL standards will allow advanced inverters to provide reactive power for voltage regulation in California.
Source: EPRI (2011)
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Advanced Inverters – Voltage Ride Through
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
110%
120%
130%
140%
Volta
ge
Time (1 sec/div.)
EXISTING AND RECOMMENDED VOLTAGE RIDE THROUGH
EXISTING IEEE-1547
LIMIT d
LIMIT c
EXISTING IEEE-1547
LIMIT a
LIMIT b
Source: CPUC Advanced Inverters Working Group, SCE Comments, 2013
Enhanced Ride Through
U.S. standards require inverters to automatically disconnect from the grid during any voltage event. Proposed changes to IEEE 1547a in California would allow ride through, enhancing system resilience.
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Advanced Inverters – Reactive Power
P90%
Q 43.6%
S100%
REACTIVE (Q)
REAL (P)
P: Real power (kW)Q: Reactive power (kVAr)S: Total power (kVA)
100 kW solar PV AC power100 kVA inverter capacity0.9 power factor43.6 kVAr reactive power90 kW real power
Standard-sized inverter:Diverts up to 10% solar capacity
to provision reactive power
Advanced Inverter at 0.9 Power Factor = 43.6% reactive power
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Advanced Inverters – Reactive Power (Oversized)
P100%
Q 45.8%
S110%
REACTIVE (Q)
REAL (P)
100 kW solar PV AC power110 kVA inverter capacity0.9 power factor45.8 kVAr reactive power100 kW real power
Oversized inverter:• No reduction of PV real power• Draws up to 10 kW real power
from the grid• Provides reactive power
24/7/365
P: Real power (kW)Q: Reactive power (kVAr)S: Total power (kVA)
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Advanced Inverters – Costs for Producers
UC Berkeley (2013)
Oversize InverterCost = (Oversized Inverter)
- (Standard Inverter)
Lose Peak Real Power
An example:• 10 kW PV system• Located in SF ($0.149/kWhr)• Peak over 2 hours, PF = 0.9• Lose $109/kVAr-yr
An example:• 10 kW PV system• 11 kW Inverter• Cost = $113.5/kW
• Produce PF = 0.9• Produce 1.2 kVAr• Cost $1.2/kVAr-yr
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Energy Storage Keeps Voltage in Balance
Photos: CESA (2013)
Storage can perform all voltage regulation functions:• In addition to provisioning real power, generally paired with advanced
inverters that can provision reactive power• Batteries and flywheels can react automatically within fractions of a
second
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Conservation Voltage Reduction
120 Volts vs. 117 Volts = 2.5% drop in power usage
Potential to reduce total system power usage by up to 3%
Pacific Northwest National Laboratory (2010)
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DG+IG Enhances System Efficiency & Reliability
• Overview of Grid Support Services
• DG+IG Balances Voltage
• DG+IG Balances Power & Frequency
• DG+IG Can Replace SONGS
Making Clean Local Energy Accessible Now
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DG+IG Balances Power & Frequency
Source: NERC (2011)
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Frequency Regulation Capacity Requirements
Navigant / Pike Research projects that U.S. frequency regulation capacity requirements will increase. In 2011, assets that provide frequency regulation amounted to about 1% of peak load.
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DG+IG Solutions for Balancing Power & Frequency
Solutions Benefits
Demand Response
• Automated demand response can address power imbalances within fractions of a second
• Reduces or shift load away from peak hours to free up other resources to provide real power
Energy Storage(batteries, flywheel)
• Supplies and absorbs power• Can reduce or shift load• Can react automatically within fractions of a second
Forecasting • Forecasting improvements will reduce unpredicted differences between scheduled supply and actual supply
Proactive Ramp Control
• Reduce output from intermittent generators for proactive ramp control to smooth out short term variations
Curtailment • Curtail intermittent generators to flatten system-wide steep ramps
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DG+IG Keeps Power in Balance
DR, ES
shifts load
ES, Auto-DR, Curtailment for
ramping
DR, ES
shifts load
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Power Balancing – Location Matters
Efficientpower
balancing
Benefits of distributed power balancing:• Avoids line losses • Reduces congestion of T&D lines
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DG+IG: Fast & Accurate Frequency Regulation
FERC Order 784 (July 2013) requires transmission providers to consider “speed and accuracy” when determining reserve requirements for frequency response and regulation.
Conventional Spinning GeneratorFlywheel Storage
Storage provides both supply and
demandFaster and more accurate
regulation = less MW required
Source: Beacon Power (2011)
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Proactive Curtailment for Ramp Control
• For an individual variable generation system, reduce output to control ramp down when there’s a forecasted reduction in solar/wind resources, and limit output to control ramp up.
• Puerto Rico requirement – no more than 10% of nameplate can change within 1 minute.
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 390
20
40
60
80
100
120
Solar_CloudsSolar_Ramped
Forecast system detects cloud edge moving toward PV installation and prepares curtailment order
Start curtailment ramp down
Start curtailment ramp up
Minutes Source: Clean Coalition (2013)
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Proactive Curtailment for Ramp Control (Cont’d)
• Cost Considerations• Proactive curtailment is less expensive for solar project owners than investing
in storage in some situations.• Proactive ramp down requires MC2 equipment – must be able to monitor and
forecast resource reduction, communicate between equipment at the site, and control ramp up and down.
• Some utilities may claim that weather monitoring equipment will be expensive
• SMUD concluded that monitoring can be done with inexpensive solar battery systems generally used for grid communications.
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Frequency Response is a Regional Issue
Western Electricity Coordinating Council
(WECC)
California Independent System Operator
(CAISO)
Each ISO must provide a certain amount of real power to respond to the sudden loss of a large generator or transmission line within the region.
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Frequency Response – CAISO Obligations
Source: California ISO Frequency Response Study by General Electric (November 2011)
CAISO contribution ~650 MW
Less than 10 seconds to
respond
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Solutions for Frequency Response
Solutions Benefits
Conventional Response
(spinning reserves)
• Traditionally, in California, natural gas power plants are kept in spinning mode to meet this need.
• These spinning reserves run less efficiently b/c not running at maximum rated output.
Energy Storage(batteries, flywheel,
pumped hydro)
• Energy storage may be used to dispatch power for frequency regulation within less than a second or up to 5 seconds, depending on the technology.
• California Public Utilities Commission has set energy storage procurement targets of 1.325 GW by 2020.
Automated Demand Response
• Automated demand response can reliably free up power supply to respond within fractions of a second.
• Most existing demand response in California is too slow and not dependable enough to participate in frequency response.
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DG+IG Enhances System Efficiency & Reliability
• Overview of Grid Support Services
• DG+IG Balances Voltage
• DG+IG Balances Power & Frequency
• DG+IG Can Replace SONGS
Making Clean Local Energy Accessible Now
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Joint Taskforce Plan for Replacing SONGS / OTC
Joint Taskforce (CPUC, CEC, CAISO) Preliminary Reliability Plan (Sept 2013)• Issues:
• Replace SONGS and ~5000 MW of retiring Once-Through-Cooling Plants• Address load growth in target areas through 2022
• Solutions: • Meet 50% of needs with 3,250 MW of local preferred resources (energy
efficiency, demand response, renewables, combined heat and power, storage)• Meet 50% of needs with transmission upgrades (including voltage support)
and 3,000 MW of conventional generation
Source: CPUC July 15, 2013
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Replace SONGS with IG SolutionsClean Coalition Solutions:• Recognize the full potential of local preferred resources.
• Plan assumes low capacity factor for demand response. CPUC should set realistic but ambitious demand response targets.
• Plan does not include use of advanced inverters to provision reactive power. CPUC should develop pilot project for Southern California.
• Maximize use of local preferred resources.• 50% limitation on local preferred resources is arbitrary, based on outdated
assumptions about the potential of local preferred resources, and not in compliance with the Loading Order.
• Southern California Edison’s Living Pilot should be a showcase for using local preferred resources to meet grid reliability needs.
Policy Forums:• CPUC Long Term Procurement Plan Track 4 (SONGS)• CPUC SCE Living Pilot• CEC Integrated Energy Policy Report• CPUC Demand Response
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Replace SONGS – Demand ResponseCalifornia must implement FERC Order 745 and greatly expand use of demand response. PJM was the first grid operator to comply with Order 745, and now demand response bids into PJM markets and responds like a generator.
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Replace SONGS – Solar Potential
SMUD installed 100 MW of local solar in just 2 years. Equivalent to 2.5 GW of local solar if a similar program were extended across the entire state.
Eric Garcetti committed to 1,200 MW of local solar within
LA city limits by 2016
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Replace SONGS – Solar PV + Advanced Inverters
Huntington Beach 290 MVars
(minus line losses = 261 MVars)
vs.
570 MW of local solar with advanced inverters, oversized by 10% set at 0.9 Power Factor = 261 MVArs
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Replace SONGS – Energy Storage Potential
Targets set by CPUC include 745 MW storage in Southern California