a semi-modular-based and sic-based smart transformer
TRANSCRIPT
Chair of Power ElectronicsChristian-Albrechts-Universität zu KielKaiserstraße 224143 Kiel
A Semi-modular-based and SiC-based Smart Transformer
Prof. Marco Liserre
06.6.2018
Chair of Power Electronics | Marco Liserre | [email protected] 1
Studentische Hilfskräfte (HiWis)
Abschlussarbeiten
Chair of Power Electronics at CAU
Prof. Dr.-Ing. Marco Liserre (Lehrstuhlinhaber) Prof. Dr.-Ing. Friedrich W. Fuchs (Pens.) Dr.-Ing. Markus Andresen, Dr.-Ing. Rongwu Zhu, Dr.-Ing. Giovanni De Carne Prof. Costas Vournas, NTUA, Griechland (Lehrauftrag + Gastprofessor), Prof. Hossein Immanini ,
University of Tehran, Iran, Nimrod Vazquez Nava, Instituto Tecnologico de Celaya, Mexico 3 Sekretärinnen + 2 Labortechniker 20 wissenschaftliche Mitarbeiter +
Chair of Power Electronics | Marco Liserre | [email protected] 2
- Associate Prof. at Politecnico di Bari, Italy
- Professor – Reliable Power Electronics at Aalborg University, Denmark
- Professor and Head of Power Electronics Chair at Christian-Albrechts-Universität zu Kiel, September 2013
− Listed in ISI-Thomson report World’s Most Influential Minds
− Active in international scientific organization (IEEE Fellow, journals, Vice-President, conf. organization)
− EU ERC Consolidator Grant (only one in EU in the field of power sys.)
− Created or contributed to the creation of several scientific laboratories
Head of the Chair: Prof. Dr. Ing. Marco Liserre
Chair of Power Electronics at CAU
Senior People of the ChairDr.-Ing. Rongwu Zhu
− PhD in University of Aalborg
− Several Projects in Wind Power System
− 13 Journal articles
Dr.-Ing. Markus Andresen
− PhD from CAU Kiel
− Visiting scholar at University of Wisconsin, Madison (USA), 2017
− 12 Journal articles
Dr.-Ing. Giovanni De Carne
− PhD from CAU Kiel
− Visiting scholar at Georgiatech (USA), 2017
− 12 Journal articles
Chair of Power Electronics | Marco Liserre | [email protected] 3
Chair of Power Electronics
50 (Year) 2 Mill Euro (Year)
People Funding
Cooperation with20 companies
60 articles every year(20 in journals)
Chair of Power Electronics | Marco Liserre | [email protected] 4
Chair of Power Electronics
Competence in PE Applications
Wide-Band-Gap SemiconductorsElectric Vehicles, Electrical Drives,
Aerospace
Isolated DC/DC-ConverterElectrical Vehicles, Active Grid, Aerospace
Control of Inverters
Industrial Drives, Active Grid, HVDC, Power Quality, Wind Energy, Electrical Vehicle,
Aerospace
Multilevel Modular Converters Wind Energy, Active Grid, HVDC
Lifetime and ReliabilityWind Energy, Industrial Drives, Active Grid,
HVDC, Aerospace
Chair of Power Electronics | Marco Liserre | [email protected] 5
Grid Integration of inverters
in PSCAD in one of the seveninverters
Test of inverter in realistic grid conditions
Features:
RTDS with 2 racks
Power Amplifier voltage or current controlled
7 inverters controlled through Dspace
Chair of Power Electronics | Marco Liserre | [email protected] 6
Thermal Analysis of power converters
Setup for „Thermal Characterization of powerelectronic Converters“ (TC-PEC)
• High speed IR Camera with positioningsystem, AC & DC Voltage Sources, Electronicloads, Oscilloscope, Power Analyzer,Synchronization & Control system
IR-camera with positioning system for junctiontemperature measurement in modular power converters.
Chair of Power Electronics | Marco Liserre | [email protected] 7
Medium-Voltage (MV) Laboratory
Planned Contruction Work in Building (Stand Oktober 2015).
Planned test for the MV Lab
Chair of Power Electronics | Marco Liserre | [email protected] 8
Table of Contents
Smart Transformer in the electric grid Semi-modular topologies Comparison between MMC and CHB Comparison between DAB and QAB Results of the actual prototype Reliability/Maintenance challenge of the Smart Transformer Smart Transformer and Solid State Transformer tailored for the grid
Chair of Power Electronics | Marco Liserre | [email protected] 9
Table of Contents
Smart Transformer in the electric grid Semi-modular topologies Comparison between MMC and CHB Comparison between DAB and QAB Results of the actual prototype Reliability/Maintenance challenge of the Smart Transformer Smart Transformer and Solid State Transformer tailored for the grid
Chair of Power Electronics | Marco Liserre | [email protected] 10
What is the „Smart“ Transformer?
The Smart Transformer is:– a “power electronics based” transformer– a power system management node– a link to different ac or dc infrastructures– a possible storage-integration technology– a link to other energy sources (gas, heat, hydrogen)– a support for the EV infrastructure
The Smart Transformer relieves thedemand on single renewable sources andincreases the capacity of electrical lines
Chair of Power Electronics | Marco Liserre | [email protected] 11
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] 12
“Power electronics based” transformer in traction application
Traditional solution• LF transformer (16 2/3 Hz) – very bulky and heavy• Low efficiency: 90 ~ 92 %• Around 7tons
Main concern:• Reduce volume and weight • Efficiency improvement
Chair of Power Electronics | Marco Liserre | [email protected] 13
“Power electronics based” transformer in distribution application
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
The Smart Transformer
Chair of Power Electronics | Marco Liserre | [email protected] 14
Smart Transformer in the electric grid
The Smart Transformer features shall be:– LV and MV DC-links available
– Advanced control of all the three-stages
– The system should be able to work even with faulty
modules
– During partial loading conditions it should be able to
fully use its rating for other services
Chair of Power Electronics | Marco Liserre | [email protected] 15
Smart Transformer in the electric grid
• Voltage support (steady state and LVRT)
• Reactive power compensation at HV/MV substation
• Power quality improvements• Islanding control (high DG in LV)
• Integration of EV-charging stations • Integration of storage for dispatching• Reverse Power Flow limitation
Smart Transformer
• Impedance identification• Load identification• Reverse Power Flow limitation• ST overload control• Soft-load reduction• Damping of harmonics and resonances• LV-side power quality
Chair of Power Electronics | Marco Liserre | [email protected] 16
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] 17
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] 18
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] 19
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] 20
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] 21
Target: Efficiency
Reliability
Accurate losses modeling
Automatic design - (optimum parameter selection)
Wideband gap devices
Fault tolerant topology
Lifetime devices considerations
Series-Resonant Converter
Chair of Power Electronics | Marco Liserre | [email protected] 22
• Wideband-gap devices plays an important role• Design: correct parameters selection
Max Eff = 98.61%Eff (@Pmax) = 98.1%
Overview of basic dc-dc topologiessuitable to be used as a building block ofthe ST dc-dc stage
CAU Kiel dc-dc converter
Influence on efficiency:
Series-Resonant Converter
Chair of Power Electronics | Marco Liserre | [email protected] 23
Fault Tolerant Series-Resonant Converter
Series-Resonant Converter
Regulated output voltage
Chair of Power Electronics | Marco Liserre | [email protected] 24
• Wideband-gap devices plays an important role• Design: correct parameters selection
Max Eff = 97.5%
Overview of basic dc-dc topologiessuitable to be used as a building block ofthe ST dc-dc stage
CAU Kiel dc-dc converter
Influence on efficiency:
Quadruple Active Bridge
(SiC)
Highest efficiency of a MAB converter
Chair of Power Electronics | Marco Liserre | [email protected] 25
DC/DC for the Smart Transformer
Dual/Quad Active Bridge Serie Resonant Converter
controlability
Voltage and current sensors
simplicity
LVDC link controlDAB VSI
Chair of Power Electronics | Marco Liserre | [email protected] 26
Dual/Quab Active Bridge Serie Resonant Converter
• CHB controlsthe MVDC linkand, consequenltythe LVDC link
• DAB controls the LVDC link
DC/DC for the Smart Transformer
Chair of Power Electronics | Marco Liserre | [email protected] 27
Electric Car Charging Station
DC distribution for higher efficiency
Load Control to smooth effect of the charging
The needed charging power is increasing and the peak charging power is challenging the electric grid
Problem
Solution
Chair of Power Electronics | Marco Liserre | [email protected] 28
Datacenter
Connectivity among several busses
Higher reliability
In 2016, the average cost of an unplanned outage per minute was nearly $9,000 per incident and the most expensive cost of an unplanned outage was higher than $17,000 per minute. The requested reliability for this application is 99.999%
Problem
Solution
Chair of Power Electronics | Marco Liserre | [email protected] 29
Aerospace
Higher Safety because of more connectivity
Lower Volume and Weight because of less magnetic component
The military standard (MIL-STD-704F) has rigorous requirements on the reliability and uninterrupted operation of the aerospace power supply system. According to NPRD-95, the failure rate of the inverter is 6.7123 per million hours and the failure probability is 0.006699 in 1000 hours.
Problem
Solution
In cooperation with Prof. G. Buticchi, Nottingham electrification center, Ninbo China
Chair of Power Electronics | Marco Liserre | [email protected] 30
Table of Contents
Smart Transformer in the electric grid Semi-modular topologies Comparison between MMC and CHB Comparison between DAB and QAB Results of the actual prototype Reliability/Maintenance challenge of the Smart Transformer Smart Transformer and Solid State Transformer tailored for the grid
Chair of Power Electronics | Marco Liserre | [email protected] 31
Semi-modular topologies
Modulation level– Cell level– Converter level– System level
Different modular levels can be freely combined
Chair of Power Electronics | Marco Liserre | [email protected] 32
Semi-modular topologies
Concept of semi-modular
Modular Architecture:Basic modules are used as building blocks for the entire ST
Basic Module
Semi-Modular Architecture:The building block is composed by several cells and a central (unreplaceable) element. In this case: Multiwinding transformer
Chair of Power Electronics | Marco Liserre | [email protected] 33
Semi-modular topologies
Asymmetrical vs. SymmetricalPossible configurations
Generic Asymmetrical
• MV side: 3 cell• LV side: 1 cell
Symmetrical
• MV side: 2 cell• LV side: 2 cell
Chair of Power Electronics | Marco Liserre | [email protected] 34
Semi-modular topologies
1. DAB-Based• Standard / Benchmark• 9 MV cells – 9 Units
2. Assymetrical QAB• 9 MV cells – 3 Units• Same voltage – MV side
3. Symetrical QAB – (V)• 10 MV cells – 5 Units• Same voltage – MV side• Less power per unit
4. Symetrical QAB – (P)• 6 MV cells – 6 Units• Same power rating / unit• less MV cells
1. DAB-Based 2. Assymetric QAB 3. Symetric QAB – (V)
4. Symetric QAB – (P)
Chair of Power Electronics | Marco Liserre | [email protected] 35
Table of Contents
Smart Transformer in the electric grid Semi-modular topologies Comparison between MMC and CHB Comparison between DAB and QAB Results of the actual prototype Reliability/Maintenance challenge of the Smart Transformer Smart Transformer and Solid State Transformer tailored for the grid
Chair of Power Electronics | Marco Liserre | [email protected] 36
Comparison between MMC and CHB
The Comparison is carried out for different blocking voltages and different grid voltages
Chair of Power Electronics | Marco Liserre | [email protected] 37
Comparison between MMC and CHB
Chair of Power Electronics | Marco Liserre | [email protected] 38
Comparison between MMC and CHB
Chair of Power Electronics | Marco Liserre | [email protected] 39
Optimal design of the CHB+DC/DC
Chair of Power Electronics | Marco Liserre | [email protected] 40
Optimal design of the CHB+DC/DC
Chair of Power Electronics | Marco Liserre | [email protected] 41
Optimal design of the CHB+DC/DC
Chair of Power Electronics | Marco Liserre | [email protected] 42
Optimal design of the CHB+DC/DC
Chair of Power Electronics | Marco Liserre | [email protected] 43
Optimal design of the CHB+DC/DC
Chair of Power Electronics | Marco Liserre | [email protected] 44
Table of Contents
Smart Transformer in the electric grid Semi-modular topologies Comparison between MMC and CHB Comparison between DAB and QAB Results of the actual prototype Reliability/Maintenance challenge of the Smart Transformer Smart Transformer and Solid State Transformer tailored for the grid
Chair of Power Electronics | Marco Liserre | [email protected] 45
Comparison between DAB and QAB
Comparative analysis: considering different semiconductor technologies1. Design consideration
• Semiconductors / Capacitors / Heatsink
• Magnetics (wire losses and cost)
• Auxillaries (gate driver, power supply,
communication)
2. Specifications 3. Design algorithm
Chair of Power Electronics | Marco Liserre | [email protected] 46
Comparison between DAB and QAB
Comparative analysis – results of performance (losses/kw) and cost1. DAB-Based
• Standard / Benchmark• 9 MV cells – 9 Units
2. Assymetrical QAB• 9 MV cells – 3 Units• Same voltage – MV side
3. Symetrical QAB – (V)• 10 MV cells – 5 Units• Same voltage – MV side
4. Symetrical QAB – (P)• 6 MV cells – 6 Units• Same power rating per unit
Chair of Power Electronics | Marco Liserre | [email protected] 47
Comparison between DAB and QAB
But…why QAB and NOT DAB? Around 20% of cost reduction when AQAB
is adopted
Chair of Power Electronics | Marco Liserre | [email protected] 48
Comparison between DAB and QAB
But…why QAB and NOT DAB?
• Less semiconductor on the LV side, but with higher current rating.
• Few impact on the cost
Reduced number of:• Auxilar components (GDU, APS and control)• Semiconductors on LV side
Around 20% of cost reduction when AQAB
is adopted
Chair of Power Electronics | Marco Liserre | [email protected] 49
Comparison between DAB and QAB
But…why QAB and NOT DAB? • DAB and QAB have similar efficiencies (only 5% of difference in favor of
the QAB)
• SiC offers 10% of losses reduction, but increase the cost in around 40%
Chair of Power Electronics | Marco Liserre | [email protected] 50
Optimal QAB design
Chair of Power Electronics | Marco Liserre | [email protected] 51
Table of Contents
Smart Transformer in the electric grid Semi-modular topologies Comparison between MMC and QAB Comparison between DAB and QAB Results of the actual prototype Reliability/Maintenance challenge of the Smart Transformer Smart Transformer and Solid State Transformer tailored for the grid
Chair of Power Electronics | Marco Liserre | [email protected] 52
Results of the actual prototype
Semi-modular – 3 stage architecture Specification:• Three-phase system• MVAC: 2.6 kVrms (line-to-line)• LVDC: 800 Vdc• Power: 100 kVA (33 kVA x 3)Features:• Power stage: MVAC-MVDC-LVDC
- MV stage: CHB- DC-DC stage: QAB
• Available funcionalities- Bidrectional power flow- VAr and voltage
compensation in both MV/LVAC
- LVDC connectivity<Semi-modular architecture>
Chair of Power Electronics | Marco Liserre | [email protected] 53
Results of the actual prototype
<Developed scaled prototype> <QAB (top) and CHB (bottom)>
Chair of Power Electronics | Marco Liserre | [email protected] 54
Results of the actual prototype
Efficiency measurement: QAB and the whole prototype (QAB+CHB)
<QAB efficiency> <Whole prototype efficiency>
Chair of Power Electronics | Marco Liserre | [email protected] 55
Same unit circuit, but… NEW configuration
New Topology: interphase use of QAB
Combining them . . .
Chair of Power Electronics | Marco Liserre | [email protected] 56
Power delivered to dc-buses is always balanced
Multi dc-buses easlypossible
Easy maintenance
New Topology: interphase use of QAB
Chair of Power Electronics | Marco Liserre | [email protected] 57
Table of Contents
Smart Transformer in the electric grid Semi-modular topologies Comparison between MMC and CHB Comparison between DAB and QAB Results of the actual prototype Reliability/Maintenance challenge of the Smart Transformer Smart Transformer and Solid State Transformer tailored for the grid
Chair of Power Electronics | Marco Liserre | [email protected] 58
Lifetime target in various PE applications
Applications Typical design target of LifetimeAircraft 24 years (100,000 hours flight operation)Automotive 15 years (10,000 operating hours, 300,000 km)Industry motor drives 5-20 years (40,000 hours in at full load)Railway 20-30 years (10 hours operation per day)Wind turbines 20 years (18-24 hours operation per day)Photovoltaic plants 20-30 years (12 hours per day)
Applications from which companies participated in the study.
• The Different O&M program
Designed lifetime target for the different applications.Data source: KDEE Kassel, Chair of Power Electronics, Kiel, Investigation of reliability issues in power electronics, ECPE study, 2017.
Chair of Power Electronics | Marco Liserre | [email protected] 59
Solutions for high reliability from survey
Which trends or approaches will improve the system reliability of power electronic converters in the future?
Scale: Not beneficial 1 to very beneficial 6
Please rank the following options to achieve high reliability for power electronic systems
Highest priority 5 points to lowest priority 1 point
Topologies & condition monitoring
Robust components & intelligent control
Data source: KDEE Kassel, Chair of Power Electronics, Kiel, Investigation of reliability issues in power electronics, ECPE study, 2017.
Chair of Power Electronics | Marco Liserre | [email protected] 60
Reliability challenge of modular systems:
• Modular power converters consist of several components, which can potentially fail:
• Capacitors (1 dc-link per H-bridge)• Power semiconductors (8 per H-bridge)• Drivers (1 per transistor)• …
• Modular power converters obtain redundancy on the building block level
• Redistribution of the stress (Power routing)• A failure of a component can be delayed
Principle of Power routing for three building blocks.
Chair of Power Electronics | Marco Liserre | [email protected] 61
Power routing for maintenance schedule
• Components will fail and maintenance will be required
• Power routing can be utilized to control the wear out and schedule maintenance
• Power routing can be used to delay maintenance
Chair of Power Electronics | Marco Liserre | [email protected] 62
Reducing the variance of the time to the failure• Slightly different temperatures of the
devices affect different lifetimes:
• With similar loading, the lifetime will have a high variance
• With power routing the variance of the lifetime is significantly reduced
• The time to a 5% failure probability is increased and mean lifetime is also slightly increased
Chair of Power Electronics | Marco Liserre | [email protected] 63
Improving reliability of More Electric Aircraft with power routing• Reliability is crucial in aircraft applications
• Penetration of onboard power electronics converters is increasing• Thermal parameter variations and cooling system failures may
result in unexpected failures while processing equal power• Lifetime control provides better prognostic maintenance with lower
early failure probability
Chair of Power Electronics | Marco Liserre | [email protected] 64
Unbreakable HEART
Chair of Power Electronics | Marco Liserre | [email protected] 65
Table of Contents
Smart Transformer in the electric grid Semi-modular topologies Comparison between MMC and CHB Comparison between DAB and QAB Results of the actual prototype Reliability/Maintenance challenge of the Smart Transformer Smart Transformer and Solid State Transformer tailored for the grid
Chair of Power Electronics | Marco Liserre | [email protected] 66
Smart Transformer and Solid State Transformer tailored for the grid
How to rate ST and SST?
Chair of Power Electronics | Marco Liserre | [email protected] 67
Smart Transformer and Solid State Transformer tailored for the grid
How to rate ST and SST?
Chair of Power Electronics | Marco Liserre | [email protected] 68
Smart Transformer and Solid State Transformer tailored for the grid
How to rate ST and SST?
Chair of Power Electronics | Marco Liserre | [email protected] 69
Join the PhD Course
13-15 Feb 2019
Half time in Lab !
Chair of Power Electronics | Marco Liserre | [email protected] 70
Acknowledgement
Thank you for the contribution of:
• Prof. Giampaolo Buticchi (University of Nottingham, Ningbo, China)• Dr. Markus Andresen (CAU Kiel)• Levy Costa (ABB Corporate Research Center, Switzerland)• Vivek Raveendran (CAU Kiel)