Smart Transformers: which impact of the SiC technology
Transcript of Smart Transformers: which impact of the SiC technology
Chair of Power ElectronicsChristian-Albrechts-Universität zu KielKaiserstraße 224143 Kiel
Smart Transformers: which impact of the SiC technology ?
Prof. Marco Liserre
Chair of Power Electronics | Marco Liserre| [email protected] slide 1
Concept and Definition of SST
Definition
• by Mr. McMurray, 1968 : Electronic Transformer is a device based on solid state switches which behaves in the same manner as a conventional power transformer.
• by Mr. Brooker, 1980 : Solid State Transformer is a apparatus for providing the voltage transformation functions of a conventional electrical power transformer with waveform conditioning capability.
• Currently: Power electronic based solution to replace the standard LF transformer, with the features:– galvanic isolation between the input and the output of the converter. – active control of power flow in both directions– compensation to disturbances in the power grid, such as variations of input voltage, short-term sag or
swell. – provide ports or interfaces to connect distributed power generators or energy storage device
• Smart Transformer: Solid State Transformer with control functionalities and communication.
Chair of Power Electronics | Marco Liserre| [email protected] slide 2
Impact of the „Smart“ Transformer
Wind/PV systemsHarbours Charging stations Data centers
Line
mile
s
70´s
centralized peak
decentralized peak
massive investments to modernize the electric grid:
- Higher mobility of people- Electric vehicles charging infrastructure
- Renewables Energies- Booming of internet -> large data centres
Smart Infrastructures are also „lighter“ infrastructures
Chair of Power Electronics | Marco Liserre| [email protected] slide 3
“power electronics based” transformer in traction application
Main concern:• Reduce volume and weight• Efficiency improvement
Traditional solution• LF transformer (16 2/3 Hz) – very bulky and heavy• Low efficiency: 90 ~ 92 %• Around 7tons
Chair of Power Electronics | Marco Liserre| [email protected] slide 4
Main requirements• Replace the traditional LF distribution
tranformer• HF/MF isolation• Provide additional functionalities
Functionalities
• Voltage sag and harmonics compensation
• Load voltage regulation• Disturbance Rejection
• Power Factor Correction• VAR Compensation and Active
filtering• Overload and short-circuit
protection
(available dc-link)
“power electronics based” transformer in distribution application
The Smart Transformer
Chair of Power Electronics | Marco Liserre| [email protected] slide 5
The Smart Transformer
A system level optimization !
Chair of Power Electronics | Marco Liserre| [email protected] slide 6
The Smart Transformer
A system level optimization !
slide 8Chair of Power Electronics | Marco Liserre| [email protected]
Bringing valuable functionalities to the 11kV/LV network…
• Voltage regulation
• Power flow control
• Harmonic filtering
• Reactive power injection
• LVDC supply
The LV-Engine Network Concept
slide 9Chair of Power Electronics | Marco Liserre| [email protected]
SST
Substation A
11kVSubstation B
11kV
NOP
0.4kV0.4kV
P &
Q c
ontr
ol
Voltage control
SST
Substation A 11kV
Substation B 11kV
NOP-1
Substation C
11kV
NOP-2
SST
0.4kV 0.4kV
0.4kV
P &
Q c
ontr
ol
Voltage control
P &
Q c
ontr
ol
Voltage control
SST
Substation A 11kV
DC
SST
Substation A 11kV
DC0.4kV Voltage
control
SST
Substation A 11kV
Substation B 11kV
NOP-1
Substation C
11kV
NOP-2
0.4kV 0.4kV
0.4kV
P &
Q c
ontr
ol
Voltage control
Scheme 1 Scheme 2
Scheme 3 Scheme 4 Scheme 5
LV-Engine Network Trial Schems
slide 10Chair of Power Electronics | Marco Liserre| [email protected]
• Releases capacity within existing LV network for connection of future LCT generationand load prior to costly reinforcement.
• Provides distribution network with increased flexibility and adaptability to cope withuncertainties in how energy will be generated and consumed.
• Significant reduction in 11kV/LV network reinforcement caused by theuptake of LCTs & electrification of heat & transport sectors.
• Lay ground works for future LVDC network reducing customer losses(avoided losses of ~£100m annually by 2040 in EV charging)
Financial Savings:
• £62m by 2030• £528m by 2050• 16% of GBs 11kV/LV GM subs by 2050
Carbon Savings:
• 523 kt.CO2 by 2030• 2,032 kt.CO2 by 2050
Projected Network and Customer benefit
Chair of Power Electronics | Marco Liserre| [email protected] slide 11
Architectures Classification
1-stage 2-stage 3-stage
• Based on direct matrix converter
• High power density (No DC link capacitoes)
• Limited functionalities
• Based on matrix converter• Funcionalities are integrated in the LV
side converter
• Input and output completly decoupled• More bulky elements (capacitors and
inductors)• All required functionalities are aggregated
to this structure
Classification:
Number of power processing stages
Chair of Power Electronics | Marco Liserre| [email protected] slide 12
Architectures Classification
• Based on WBG semiconductors• Concept of modules and cells are
not used.• Disadvantageous for fault tolerance
scheme implemenation• No scalability in voltage
Classification:
Modularity level
Chair of Power Electronics | Marco Liserre| [email protected] slide 13
Architectures Classification
• Based on single multiwinding transformer
• Cell level modularization• Simple to implement a fault tolerance scheme
• No scalability on voltage and power
Classification:
Modularity level
Chair of Power Electronics | Marco Liserre| [email protected] slide 14
Architectures Classification
• Fully modular• Scalability in voltage and
power• Simple to implement a fault tolerance scheme
• More components
Classification:
Modularity level
Chair of Power Electronics | Marco Liserre| [email protected] slide 15
Architectures Classification
Architecture performance comparison
Eff x Power Isolation freq x Power
• The number of power stages are not directly related to efficiency• SiC-based converter has achieved higher efficiency with high frequency• Trasformer design is also a important issue for he ST implementation
Chair of Power Electronics | Marco Liserre| [email protected] slide 16
Overview - Traction
Concept:• SR LLC dc-dc converter
Prototype:• Single-phase 1.2 MVA/ 1.8 kHz• 9 modules (8+1 redundant)
Features:• Modular• Standard 6.5 and 3.3 kV IGBT• Total of 72 semiconductors
Efficiency: 96.2%Weight: 4.5 tons
• Zhao / ABB (2011)
Chair of Power Electronics | Marco Liserre| [email protected] slide 17
Overview - Distribution
Concept:• Indirect matrix converter• No capacitor on the dc link
Prototype:• Three-phase 1 MVA / 20 kHz• 13.8 kV to 415 V• 4 modules in series
Features:• Modular• SiC 10 kV Mosfets• Three power stage
• Das / GE (2009)
Theoretical Efficiency: 97%
Chair of Power Electronics | Marco Liserre| [email protected] slide 18
Overview - Distribution
• Huang / FREEDM (2015)
Concept:• Based on 13 kV SiC Mosfets• Classic structures
Efficiency: 93.4 %Max eff: 94.59 @40% of load• Rectifier: 99%• Dc/dc: 95.5 (max of 97.3%)• Inverter: 98.6%
Prototype:• Three-phase 10 kVA / 15 kHz• 3.6 kV to 120/240 V• dc grid: 400V
6kV
Features:• Not modular• Customized 13 kV SiC Mosfet• Total of 12 semiconductors• 3 processing stages
Chair of Power Electronics | Marco Liserre| [email protected] slide 19
Overview - Distribution
• ETH (2011)Concept:• 3 Port SST for to improve the power management• Distribution application: 1 MVA / 10 kV to 400V
Features:• Modular• Three power stage• Available LVDC link
Chair of Power Electronics | Marco Liserre| [email protected] slide 20
Overview - Distribution
• HEART (2017)Concept:
• Semi-modular• Based on asimmetrical QAB• Inter-phase arrangment of the QAB
Features:• Power delivered to dc-buses is always
balanced• Multi dc-buses easly possible• Low-voltage dc-link has no double
frequency oscillation • Easy maintenance
Chair of Power Electronics | Marco Liserre| [email protected] slide 21
Challenges of the DC-DC Stage
• High voltage Isolation• High Input voltage • High output current• Galvanic Isolation in Medium/High frequency• Power flow control – dc link control• Dc breacker feature (short circuit current
proctection)
DC-DC Stage: The most challenge stage
IsolationEfficiencyCost
Deserves more attention
Chair of Power Electronics | Marco Liserre| [email protected] slide 22
Implementation: DC-DC Stage
Dual-Active-Bridge (DAB) Series-Resonant Converter (SRC) Multicell converter
•Less number of HF transformer
•Operates similarly to eh DAB converter
•Easy to control (degree of freedom)•Efficiency: ~ 97%
•Open loop operation (no control / less sensors)
•Efficiency: ~ 98%
• Operate at high frequency and high power
• Most challenging converter: high voltage in the MV side and current in the LV side
.
Chair of Power Electronics | Marco Liserre| [email protected] slide 23
DC-DC Stage: Implementation Concept
• Low voltage/current rating semiconductors• Scalability in voltage/power• Fault tolerance capability• Reduced dV/dt and dI/dt
• Fewer number of components• High Voltage WBG devices• Simple control/communication system
Non-Modular Vs Modular
Chair of Power Electronics | Marco Liserre| [email protected] slide 24
Challenges of the DC-DC Stage
• High Voltage Isolation• Bidirectional power flow• Galvanic Isolation in Medium/High frequency• Power flow control – dc link control• Dc breacker feature (short circuit current
proctection)
DC-DC Stage: Building Block Converter
Efficiency
Chair of Power Electronics | Marco Liserre| [email protected] slide 25
Review on high efficiency dc-dc converter
Relevant converters: Phase-shift Full-Bridge Series-Resonant Converter
Dual-Active-Bridge Multiple-Active-Bridge
Chair of Power Electronics | Marco Liserre| [email protected] slide 26
Special Section Scope
Topics DC-connectivity in MV and MW range
Impact of asynchronous AC networks
Modular and non-modular approaches
Direct and indirect conversion
Feasibility and impact of 10 kV SiC
Chair of Power Electronics | Marco Liserre| [email protected] slide 27
Special Section Program- Part 1
Short Introduction to the Smart Transformer Technology, Marco Liserre, University of Kiel, Germany
15 min 12:30-12:45
1. Medium voltage direct power conversion for medium voltage solid state transformer, Alex Huang, University of Texas at Austin, USA, 25 min 12:45-13:10
2. Intelligent Solid-State DC Substation for Flexible Electrical Grids, Rik W. De Doncker, RWTH Aachen University, Aachen, Germany, 25 min 13:10-13:35
3. Measuring Impact of WBG Semiconductors on Solid State Transformers, Deepak Divan, GeorgiaTech, USA, 25 min 13:35-14:00
Short Discussion 10 min 14:00-14:10
Chair of Power Electronics | Marco Liserre| [email protected] slide 28
Special Section Program- Part 1
Chair of Power Electronics | Marco Liserre| [email protected] slide 29
Special Section Program- Part 2
5. Medium-Voltage Asynchronous Microgrid Power Conditioning System Enabled by HV SiC power devices, Subhashish Bhattacharya, NC State University, USA, 25 min 14:20-14:45
6. A Bidirectional Isolated DAB DC-DC Converter Using 1.2-kV 400-A SiC-MOSFET Modules WithoutSBD, Hirofumi Akagi, Tokyo Institute of Technology, Japan, 25 min 14:45-15:10
7. Design and Experimental Analysis of a 10 kV SiC MOSFET Based 50 kHz Soft-Switching Single-Phase 3.8 kV AC / 400 V DC Solid-State Transformer, Johannes Kolar, ETH, Switzerland, 25 min 15:10-15:35
8. 10 kV SiC MOSFET based power electronics building blocks (PEBB) for modular medium-voltagegrid-tied converter, Rolando Burgos, VirginiaTech, USA, 25 min 15:35-16:00
9. A Semi-modular-based and SiC-based Smart Transformer, Marco Liserre, University of Kiel, Germany, 15 min 16:00-16:15
Short Discussion 10 min 16:15-16:25