Colin Davidson – Chief Technology Officer, HVDC – Alstom Grid

Andrew Bennett – Principal Engineer – MathWorks

LARGE-SCALE ADOPTION OF MODEL-

BASED DESIGN FOR PRODUCTION OF

HVDC TECHNOLOGIES

WHO IS ALSTOM GRID?

• Alstom Grid designs, manufactures and supports electrical power transmission equipment and turnkey projects.

• We are one of three sectors of Alstom Group (Alstom Power, Alstom Transport and Alstom Grid)

• Customers from 24 countries around the globe including: India, USA, Australia, Mexico, Italy, Russia, Spain, Canada, Turkey, the Netherlands and many more.

• Major player in global HVDC market and one of only three suppliers in the developed world.

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OVERVIEW – SO, WHY ARE WE HERE?

To discuss the adoption of a Model-Based Design process on a new design of High Voltage Direct Current Transmission (HVDC):

• Voltage Sourced Converter (VSC)

• Increased complexity

• Decreased timescales

How we’re expanding the approach across all HVDC projects.

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ELECTRICAL POWER TRANSMISSION

• Early history: the “Battle of the Currents”

- George Westinghouse (AC) VS Thomas Edison (DC) - Edison tried to convince the public that AC was too

dangerous, but the superiority of it was too much for DC to overcome

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George Westinghouse

(AC)

Thomas Edison (DC)

• Power loss is proportional to the square of the current

- Increase voltage lower current lower losses

• Invention of the transformer allowed voltage to be stepped up for transmission

- But transformers only work for AC AC power transmission network - Hence AC became the preferred medium

• However, AC transmission is hard to control (power flows where it wants to flow)

• High Voltage Direct Current (HVDC) transmission is more efficient and more controllable

BENEFITS OF HVDC

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A.C.1850 MW per Circuit.

400k.V. 12 x 282 mm2

D.C. 1850MW Per Circuit.

± 250k.V. 4 x 644 mm2

Station

Cost

DC

Converter

Stations

AC

Stations

DC

AC

Break Even

Distance

Transmission

Distance

• Greater power density in a given corridor

• Higher efficiency

• Distance break-even point (HVDC versus HVAC)

- Underground or submarine cables > 30 miles - Transmission lines > 500 miles

• Improved real time power flow control

- Power flows where you want it to

• Increased power system reliability and security

• Improved power system transient and dynamic stability

ALSTOM GRID 24MW VSC DEMONSTRATOR

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• 24MW Back to Back HVDC station in the heart of Stafford

OLD (Jan 2011)

NEW (Jul 2013)

SYDVÄSTLÄNKEN (SOUTH-WEST LINK) PROJECT IN SWEDEN

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• Alstom’s first commercial VSC-HVDC order

2 X Converter

stations (in Norway)

HURVA

2 x Converter stations

BARKERYD

2 x Converter stations

• 2 complete HVDC links,

each rated at 720MW,

±300kV

• Total of 8448 “submodules”

each containing a pair of

IGBTs and a capacitor

• Every submodule has to be

independently controlled

but centrally coordinated

• Control cycle time <100μs

WHY MODEL-BASED DESIGN FOR HVDC VSC?

Needed to design and test a system with many levels of complexity:

- Hierarchical Control and Protection System:

• High Level Sequencing with interaction with the power system

• Cascaded Control Loops

• Firing of individual power electronic switches - Need plant models to help properly design control system and verify its operation early on

Need to deploy control and protection systems to a wide variety of real-time hardware:

- Micro-processors - DSP’s - FPGA’s

Achieved tight timescales – concept to 24 MW demonstrator in 2 years

- Enabled by MathWorks consulting and training services

Production contracts awarded

- > €1billion

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“In the design of VSC systems, effective verification and validation is paramount to achieve the complexity, quality,

required reliability, and time to market targets.”

Process Previous HVDC

time taken

VSC time taken

(Model-Based Design)

Overall development effort 100 man years 10 man years

Original design to code (1st

time model elaboration)

> 2 years 3 months

Integration with Desktop

Power System Simulation

Software (PSCAD/EMTDC)

> 6 man months < 2 weeks

Subsequent design

iterations

> 2 months < 1 week

Testing > 2 weeks 8 hours

Documentation update > 2 weeks 10 minutes

INITIAL DEMONSTRATOR BENEFITS

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METRICS

Model metrics

• Total model (2* controllers, 2* converters, + associated plant)

2,000 subsystems containing 33,000 blocks

564 discrete states and 250 Stateflow charts

750 bus creators and 250 bus selectors

53 Scopes

Code metrics

• 10,000 lines of code generated • Zero errors detected • No modifications to generated code

Documentation metrics

• 339 pages of documentation generated

Metrics above from 2011, now models significantly expanded and ~200,000 lines of code generated

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ITERATIVE VERIFICATION AND VALIDATION PROCESS

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Desktop Grid

Simulation

Production

System

Desktop

Simulation

Hardware Simulator

Hardware Demonstrator

MAIN MATHWORKS PRODUCTS IN USE

MATLAB • Analyse and automate

Simulink • Control design

Stateflow • Sequencing/supervisory control • Protection systems

SimPowerSystems • Electrical plant simulation

Embedded Coder • Deploy control and protection algorithms to other

desktop simulation tools, production micro-processors and DSP’s

• Deploy plant models for Hardware-In-Loop

Report Generator • To permit automatic up-to-date document creation

Simulink Verification & Validation • Model checking • Requirements traceability • Coding standards

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IMPLEMENTATION AND ADOPTION

Expanding a Model-Based Design approach to all HVDC Projects

• Team development

• Early testing to reduce issues late in product lifecycle

• Conversion of legacy code for existing technologies into Simulink models

• Development of Model Advisor Checks

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TEAM DEVELOPMENT

• Scaling up & migration of pre-existing product

• VSC Development team grown by 200% in 2 years • Existing product development team moving to

MATLAB and Simulink

• Staff development

• Internal engineering workshops • Regular onsite MathWorks training courses • MathWorks consulting support

• Recruitment pool has widened significantly

• Traditionally focused on people with very specific software and specific power electronics backgrounds

• Now broadened reach to include people with Model-Based Design and Embedded Systems knowledge.

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EARLY TESTING

• Implementation tests – for parts of system

• Associated test bench • Pass or fail

• Scenario tests – for full system

• Scenarios

• Start-up

• Full load

• Faults (AC 1-φ, 2-φ and 3-φ, DC)

• Shutdown • Regular observation and review of the results

• Provides early testing by development team, reduced issues late in project lifecycle

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MIGRATION OF EXISTING PROJECTS

• Legacy Code Tool (LCT) to wrap existing modules

• Permits import • Permits deployment with TLC

• All testing within MATLAB and Simulink

• Anything new – directly written in MATLAB and Simulink

• Modules that need modification – are being moved to MATLAB and Simulink

• Pragmatic approach enables efficient realisation of Model-Based Design benefits

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MODEL ADVISOR

• Making extensive use of Model Advisor

• Existing checks – particularly MAAB Style guidelines • Variety of custom checks to implement internal guidelines

• Ensures consistency and efficient collaboration

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OVERALL BENEFITS

• Turnaround of projects is quicker

• Used to discover issues late in development process and required significant resources for final testing

• Many fewer issues discovered late in development – because much more testing as we go

• Better integration between algorithm and implementation

• Both teams speaking the same language • Better architecture/structure

• Building a library of re-usable parts, of use to both

• Algorithm engineers • Implementation engineers

• Implementation of model style guidelines and checking to improve consistency and collaboration

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SUMMARY

Model-Based Design adopted widely across engineering team on new and existing projects

Design, implementation and testing completed using MATLAB & Simulink multi-domain models

Models are then used to:

- Verify and validate sequencing, closed loop control and protection systems - Automatically generate production code

• Desktop simulation through to production

• Exactly the same code tested and running on all platforms - Automate testing early in project lifecycle - Automate document generation

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CONCLUSION

The evolution to a Model-Based Design approach at Alstom Grid enables:

• Rapid development, verification and validation of complex systems

• Increased engineering productivity

• Ability to scale up product customisation from a few schemes to many schemes per year

• Verified and validated production designs in significantly less time than the previous design process

• Project wins worth > €1billion – positive impact on business