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© 2018 Electric Power Research Institute, Inc. All rights reserved.
Dr. Ram Adapa Technical Executive, EPRI
SNL Workshop on Enabling Advanced Power Electronics Technologies for the Next Generation Electric Utility Grid
Albuquerque, NMJuly 17-18, 2018
Power Electronics &
Power Flow Control
TechnologiesTechnology Assessment
2© 2018 Electric Power Research Institute, Inc. All rights reserved.
Setting the Stage
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
The Power Electronics Revolution
Opportunities to:
Reduce energy use
Enhance the functionality of the power system
Enable the integration of renewables
Facilitate the creation of a low-carbon energy
future
3© 2018 Electric Power Research Institute, Inc. All rights reserved.
2000 2005 2010 2015 2020 2025 2030
7,000
6,500
6,000
5,500
5,000
4,500
4,000
3,500
3,000
2,500
2,000
En
erg
y (
Billio
n k
Wh
)
Background – Energy Savings Potential of Power Electronic Proliferation
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
Opportunity to reduce Electricity Consumption
Codes and Standards
Market-Driven Efficiency*
Achievable Potential
+ + +
Technical
Potential
Avoided Electricity Consumption in 2030 . . .
• Technical Potential ~ 26%
* Includes embedded impact of EE programs implicit in AEO 2008
4© 2018 Electric Power Research Institute, Inc. All rights reserved.
Background
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
Power Flow Control devices allow better utilization of existing transmission assets by balancing flows and mitigating loop flows
Historically system operators have had the ability to change power flows
on the transmission grid by:
– Generation dispatch and curtailment
– Tap changing on voltage/ phase angle regulating transformers
– Switching transmission lines and components
– Switching capacitor banks and reactors
– Shedding load
Power Flow Control:
ability to change the way that power flows through the grid by actuating on high
voltage devices connected in series or in shunt with transmission lines.
5© 2018 Electric Power Research Institute, Inc. All rights reserved.
Background
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
Power Flow Control in Transmission Grids
Hardware:
– Phase shifting transformers (PST)
– FACTS devices
– Intelligent Universal Transformer
– Current Limiters
– Circuit Breakers/Switches
– New devices:
CD-PAR
Transformer-less Unified Power Flow Controller (UPFC)
Distributed Series Reactors (Smart Wires)
– HVDC
Objectives of power flow control:
– Improved transmission grid utilization
– Deferred expansion
– Reduced congestion
– Reduced loop flows
– Improved operation flexibility
6© 2018 Electric Power Research Institute, Inc. All rights reserved.
FACTS (Flexible AC Transmission Systems)
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
P = V1V2 sin (1-2)1
X
V11 V22P
Transmission Line X
Passive Transmission Active Transmission
7© 2018 Electric Power Research Institute, Inc. All rights reserved.
Transmission Applications of VSC based FACTS
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
STATCOM
Voltage Control
+ -
V
Vo
Vdc
Static Synchronous Compensator
- STATCOM -
I
+ -
V
Vo
Vdc
Static Synchronous Compensator
- STATCOM -
I
+ -
V
Vo
Vdc
Static Synchronous Compensator
- STATCOM -
I
SSSC
Line Impedance Control
UPFC
Voltage, Line Impedance &
Phase Angle Control
IPFC
Interline Power
Exchange
Back-to-Back Asynchronous/Synchronous Tie
System 1
V1
System 2
+ +- -
12P
V2
Back-to-Back Asynchronous/Synchronous Tie
System 1
V1
System 2
+ +- -
12P
V2
Back-to-Back
Voltage & Power
Transfer Control
8© 2018 Electric Power Research Institute, Inc. All rights reserved.
EPRI Sponsored FACTS Installations
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
FACTS Applications are expanding around the globe
Thyristor Controlled Series
Capacitor (TCSC):
“Line Impedance
Controller”
208 Mvar TCSC at Slatt
Substation (BPA) 1993
FACTS Controller
“Back-To-Back HVDC Tie”
36 MW at Eagle Pass (CSW)
2000
Convertible Static Compensator
(CSC): “Flexible Multi-functional
Compensator” ± 200 MVA at Marcy
Substation (NYPA) 2000 & 2002
Control
Convertible Static Compensator Concept (CSC)
Optical link
- +
Inverter
HV
Optical link
- +
Inverter
Static Synchronous
Compensator (STATCOM) :
“Voltage Controller”
± 100 Mvar STATCOM at
Sullivan Substation (TVA)
1995
Unified Power Flow Controller (UPFC):
“All Transmission Parameters Controller”
± 160 MVA Shunt and ± 160 MVA Series at
Inez Substation (AEP) 1998
9© 2018 Electric Power Research Institute, Inc. All rights reserved.
Enabling the Intelligent Universal Transformer
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
Replacing legacy distribution transformers with Solid-State alternatives
Core Technologies Needed
New State-of-the-Art Power
Electronic Topology
New High-Voltage, Low-Current
Power Semiconductor Device
Interoperable with Open
Communication Architecture
Functions & Value
Traditional voltage stepping,
plus…
New service options, such as DC
Real-time voltage regulation, sag
correction, system monitoring,
and other operating benefits
Other benefits: standardization,
size, weight, oil elimination
Cornerstone device for advanced
distribution automation (ADA)
Product Spin-offs
Emergency EHV / Recovery
transformer replacement
(substations)
Other power electronic
applications
Needed: Reliable Low Voltage & High Voltage
(High Power) Solid State Transformers
10© 2018 Electric Power Research Institute, Inc. All rights reserved.
Solid State Fault Current Limiter
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
Needed: Distribution & Transmission Level Fault Current Limiters
15kV, 1200 Amp Distribution Class SSCL
Current passes through SGTO modules in normal operation
Drive modules off when detect fault event
2kV, 1000A turn off per block. Stack in series / parallel for increased
voltage / current.
Tune inductors for let-through current
11© 2018 Electric Power Research Institute, Inc. All rights reserved.
HVDC Converter Technology:
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
Line Commutated Converter (LCC) vs. Voltage Source Converter (VSC)
Line Commutated Converter
(or Current Source Converter )
• Thyristor based
• Switches on-off one time per cycle
Voltage Source Converter
• IGBT Based
(Insulated Gate Bipolar Transistor)
• Switches on-off many times per cycle
12© 2018 Electric Power Research Institute, Inc. All rights reserved.
HVDC in North America
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
North American HVDC Deployments
13© 2018 Electric Power Research Institute, Inc. All rights reserved.
Key Takeaways
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
DC Grids – The Future of DC Transmission
DC Grids for Offshore Wind
Considered more in Europe than in other countries
Need to resolve many issues
– Power & Voltage control
– DC circuit breakers
– DC / DC Transformers
– Standard DC voltages
– Communication needs
– CIGRE/IEEE WGs
Two Topologies
DC Node
AC Node
DC Line
(a)
(b)
14© 2018 Electric Power Research Institute, Inc. All rights reserved.
Macro Grid - HVDC Network Concept
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
Opportunities to expand HVDC Transmission in North America
15© 2018 Electric Power Research Institute, Inc. All rights reserved.
Key Takeaways/Insights
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
New methodologies and tools and active demonstrations are needed to accelerate the adoption of PFCs
Mature as well as emerging technologies for controlling power flows across the grid are available
PFC technologies are proven to be effective solutions to various transmission problems
Needs for wide spread adoption (Gaps):
– Deep understanding of PFC technologies relevant aspects to facilitate risk-informed decisions on the use of the technology
– New models, analysis methods, and tools to evaluate and design PFC-based solutions
– Operational practice and procedures to operate and control PFCs in an effective and reliable manner
– Appropriate regulatory mechanisms to collect the economic benefits from the investment
– New PFC models for EMS applications
To bridge the gaps:
– Develop model tools for novel active power flow control devices
– Develop framework to evaluate reliability and economic benefits of active power flow control devices
– Field demonstrations and pilot commercial installations
16© 2018 Electric Power Research Institute, Inc. All rights reserved.
Advanced Power Electronics
Silicon
Silicon Carbide
Silicon Carbide
+
Gallium Nitride
• High operating
temperature
• Lower switching
losses
• Widely available
• Low cost
• Higher Temperature
• Higher Voltage
• Optical switching
Major fundamental research is required for advances in PE materials
New power electronics materials enable newer applications and benefits
Limited Max Blocking Voltage
Limited Max Switching
Frequency
Limited Max Operating
Temperature
17© 2018 Electric Power Research Institute, Inc. All rights reserved.
Technical Innovations –
Power Electronics
Thyristor
GTO
GCT
IGBT
LTT
GTO – Gate Turn-Off Thyristor
LTT – Light Triggered Thyristor
GCT – Gate Commutated Thyristor
IGBT – Integrated Gate Bipolar Transistor
FET – Field Effect Transistor
SiC – Silicon Carbide
GaN – Gallium Nitride
Needed: Roadmap and R&D funding to achieve these higher ratings for
Wide Bandgap Devices
Probably Needed : Wide Bandgap Thyristor type (instead of transistor type) devices for High Power applications
18© 2018 Electric Power Research Institute, Inc. All rights reserved.
Future Direction
EPRI
WBG Device Manufacturers
Identify device gaps for utility
scale PE applications
Develop device specifications
Academia/Industry
Identify utility scale
applications
Lead pilot demonstrations to
evaluate performance
EPRI Research Focus
• High-voltage, high-power circuits for grid
modernization
• Efficient, reliable, and modular power
electronics for DER cost reduction
• Low-power, compact electronics for self-
powered distributed sensors
EPRI Research Approach
• Lead tech transfer by bringing
stakeholders together
• Identify gaps and opportunities through
technology scouting
• Partner with industry/academia for federal
funding opportunities
Value - Research under this program can contribute to advanced power electronics technology which can enable a fully functional and controllable power system resulting in a potential value in
excess of $1 trillion over next 20 years.
19© 2018 Electric Power Research Institute, Inc. All rights reserved.
Key Takeaways/Insights
Power Electronics – Growth Opportunity
WBG Power Electronics is key for:
– Future SMART Electric Grid (Intelligent Grid / Integrated Grid)
– Integration of renewables such as wind and solar with interconnections to the main grid
– Reducing system losses and increasing efficiency
– Increasing grid reliability and resiliency
– Reducing carbon footprint
– Enhancing quality of life
Future Needs:
– High Power Devices
– New Converter Topologies
– New PE Applications
TECHNOLOGY ASSESSMENT: POWER ELECTRONICS & POWER FLOW CONTROL
20© 2018 Electric Power Research Institute, Inc. All rights reserved.
Image from NASA Visible Earth