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Convertible Static Transmission Controller (CSTC) and Modular Transformer Converter (MTC)Modular Transformer Converter (MTC) -
A Multi-Purpose Solution forTransmission Grid Developmentp
Babak Parkhideh and Subhashish Bhattacharya
CSTC ACAC
Tech
nolo
gy
Dem
ands
MTC
Energy Transmission Outlook
AC
DC
T D
-Motivation-Power Outage Cause & Effectg
Each year a considerable number of customers are affected due to power lossEach year a considerable number of customers are affected due to power lossThese numbers can be much more!These numbers can be much more!
Based on 2002 data ti ti NLBL
EIA data
estimation, NLBL
The grid is getting aged!The grid is getting aged!The grid is more vulnerable to catastrophic natural disturbances, new generations (wind), terrorist attack, etc. The grid is more vulnerable to catastrophic natural disturbances, new generations (wind), terrorist attack, etc.
2Average age of power transformers is now approaching 40 yearsTransformer can be up to 60% of total substation cost
Transformers can have more than 3 years of manufacturing lead time
-Motivation-New Generations Effects on Existing Assets
-Wind Generations-Wind GenerationsDistributed generation units with low availability138kV Overload Lines345kV U d tili d t i ffi i t k t
Desired Power Flow
345kV Underutilized assets, inefficient market
Power Flow on 138kV Network
Spring PeakingSpring Peaking
No significant
Midwest RegionMidwest Region
No significant summer generation!
3
Midwest RegionMidwest Region
Source of generation data: NREL, E. Muljadi
-Current Technologies-Power Flow Controllers
A multifunctional productSpare transformer
Phase Shifting TransformerPhase Shifting Transformer PolyTransformerPolyTransformer
ABBAutotransformer structure, compactCan be leased or rented, transportable!Siemens
Well-experienced elementBulky and heavy
CB operationInterrupterFCL
Well-suited for major inter-area connections
Fault Current LimiterFault Current Limiter
Continuous operated FCL
FCL
PassiveIncrease of impedance at
normal and fault
Active • HV fuses
• Transformers with increased impedance
• Limiting reactors Impedance Based
4
ActiveLow impedance at normal
Increase of impedance at fault
• HV fuses• PTC resistor• Superconductor FCL• Solid-state FCL
Confidential DocumentS. Bhattacharya Solid-State solution
BasedSolutions
-Solution-Power Flow Controller at Substation
Less control complexity at substations (S/S) compared to lines (i.e. IEEE 30 Bus)
Multifunction Solid-State Solution
3 S/Ss 3029
27 283 S/Ssxxx lines
Vs Vr
Power System
1415 18
19 22
2423
r
30 27 28
25 26
G
r r
C
r
19
1620
17
10
2122
4
12
9
13C
11
Controllable
System ObjectivesSystem ObjectivesG
C
1
2
3
5
7
9
8
Power FlowBack-upFault Current Limiter (FLC)
EfficiencyReliability
Modular Transformer Converter SystemModular Transformer Converter System--MTCMTC--
System RequirementsSystem Requirements
ScalableTransportableEffective 5
Regular/No Transformers
Possible Connecting Configurations&
Mode FunctionsMode Functions
Series-Shunt ConfigurationPower Flow Control
Shunt-Shunt ConfigurationBack-up
Series-Series ConfigurationPower Flow Control
6
Power Flow ControlFCL
Back upMain Transformer Life Extension
FCLPower Flow Control
Power Flow ControlFCL
Convertible Static Transmission Controller (CSTC) with Modular Transformer Converter (MTC)
System as the Substation Power Flow ControllerSystem as the Substation Power Flow Controller
345kV/138kV 600 MVA Trafo
Convertible Static Transmission Controller
345kV/138kV, 600 MVA Trafo6 modules can double the loading of the Trafo. dynamically and provide FCL function
With minimal reconfiguration it can provide back-upHardware-based solution for asset management including life extension of the main transformer
• Versatile transmission asset• Power flow router/controller• Asset management hardware• Transportable• Transportable • Scalable• Different voltage compatible • High efficiency • Distributed DC link
7
• Distributed DC link• Retrofit into existing substations• Modular for Utilities
Convertible Static Transmission Controller (CSTC) with Modular Transformer Converter (MTC)
System as the Substation Power Flow ControllerSystem as the Substation Power Flow Controller
345kV/138kV 600 MVA Trafo
Convertible Static Transmission Controller
345kV/138kV, 600 MVA Trafo6 modules can double the loading of the Trafo. dynamically and provide FCL function
With minimal reconfiguration it can provide back-upHardware-based solution for asset management including life extension of the main transformer
• Versatile transmission asset• Power flow router/controller• Asset management hardware• Transportable• Transportable • Scalable• Different voltage compatible • High efficiency • Distributed DC link
8
• Distributed DC link• Retrofit into existing substations• Modular for Utilities
Effect of Power Flow Controllers on the Loading of A Transformerg
SeriesSeries--Shunt ConfigurationShunt ConfigurationExample of operation
1 0sV = ∠ o 1 5rV = ∠ o
Transformer Power Flow can be controlled over a wide range!
0 3
0.40.5
MTC Rating
0.1PU
MTC
0.20.3
9
MTC System for Transformer Life Extension and ContingenciesExtension and Contingencies
Passive Solution Hybrid Solution-low ratingCurrent Solution
ProposedSolution
Steady StateContingency Relief
StrategyAn Example of Distributed
MTC Systems for IEEE 30 bus
10
MTC System as Fault Current Limiter-Voltage and Impedance Control-g p
Conventional and Novel Methods : Variable Impedance
NC NC
1:n
Unified MTC based System as FLC Impedance increase toreduce the fault current
Voltage injection toreduce the fault currentOption IOption I
10~15 MVA Back-to-Back ModuleFault
10~15 MVA Back-to-Back Module
10~15 MVA Back-to-Back Module
10 15 MVA B k t B k M d l
Impedance increase toreduce the fault current
Substation incoming voltage controlto reduce the fault current
Option IIOption II
10~15 MVA Back-to-Back Module
10~15 MVA Back-to-Back Module
reduce the fault currentto reduce the fault current
11
NO
10~15 MVA Back-to-Back Module
MTC Topologies“Control”
Vector-Controlled VSC Advanced Angle-Controlled VSC
12
MTC Topologies Feasible Operating Points - Angle-Controlledp g g
Steady state calculation of operating points with different angle and power
Active Power Reactive Power
InverterRectifier
Potential of using the angle as the only controller input to hi diff l f i d i !
Angle(degree) Angle(degree)Angle(degree)
13
achieve different values for active and reactive power!
MTC Topologies – Available Tech.“Efficiency”y
Efficiency vs. semiconductor module vs. control method
* Based on detailed PSPICE modeling
14Selected results in : H. Mirzaee, A. De, A. Tripathi, and S. Bhattacharya "Design Comparison of High Power Medium-Voltage Converters based on 6.5kV Si-IGBT/Si-PiN JBS diode, and 10kV SiC MOSFET/SiC-JBS diode“ to be presented at IEEE ECCE 2011.
Convertible Static Transmission Controller (CSTC) with MTC - Option I(CSTC) with MTC Option I
MTC I P tiMTC-I PropertiesControl Method:Angle and Hybrid ControlSemiconductor:6.5 kV Si IGBT/SiC JBS DiodeMagnetic:Multi-winding Regular TransformerRegular Transformer
15
Convertible Static Transmission Controller (CSTC) with MTC - Option II(CSTC) with MTC Option II
MTC-II PropertiesControl Method:Vector ControlVector ControlSemiconductor:15 kV Si IGBT/SiC JBS DiodeMagnetic:No Series Trafo.HF Shunt Trafo.
EE
CR
E
166.7 mm x 6.7 mm 15 kV SiC p-IGBT device fabricated on 100 mm 4HN-SiC wafers
Hybrid-Controlled CSTC as Transformer Power Flow ControllerTransformer Power Flow Controller
EMTDC Simulation
17
Angle-Controlled CSTC as Transformer (Partial) Back-upTransformer (Partial) Back up
18*Preliminary results
Summary of MTC based CSTC Benefits
Single multi-functional asset Increased reliabilityUtilities’ Benefits System Benefits
Single multi functional assetPower flow router/controllerAsset management hardware solution
Increased reliabilityHigh efficiencyLow current and
Back-up system for the transformersDifferent network voltage compatible
voltage THDLow switching stressDi t ib t d DC li kTransportable
Modular in utilities’ perspective 19
Distributed DC-linkPotentially low cost
“Direction” Concept for Angle-Controlled VSC as Single Input(angle) Two Output (PQ) – SITO Sys.
GOAL: Design as SISO systems i.e. Bode plot.Alignment angle changes the properties of the
Proposed Design Guidelinesg g g p p
system in the output transfer functions.Controller should be aligned with the plant (VSC)to reduce the interaction of the states.The attenuation of the disturbance (load) depends on the alignment angle between disturbance (load)and plant (VSC).The plant (VSC) properties affects the performanceThe plant (VSC) properties affects the performance of the system for disturbance rejection.
angle
LinputL
PrefQref
anglePQ
21
Loutput
