Extreme performance: Increasing resilience and mitigating risk - Climatic tests for transformers integration with offshore wind power - CWIEME Berlin 2014 - Pieter Jan Jordaens

Extreme performance Increasing resilience and mitigating risk:

Climatic tests for transformers integration with offshore wind power

Pieter Jan Jordaens Business development & Innovation [email protected]

mailto:[email protected]




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Content

Introduction Drivers for wind energy R&D Technological Evolution – technical challenge Risk mitigation pathways

Requirements with regard to sites: focus cold climate Testing & validation: focus cold climate

Wind turbine testing in general Climate chamber testing of transformers Case study in the climatic test chamber: focus cold climate

Liquid filled transformers Cast resin transformers

Conclusion

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Introduction

Non-profit Belgian technology centre Mission: to support companies with implementing

technology innovations 160 engineers and scientists Multidisciplinary R&D and innovation projects

Mainly for Belgian companies (SME & Large) Also shared R&D projects with EU companies

High tech R&D infrastructure

Competences

High-tech Test & Monitoring

Infrastructure

Processed Data

Insights &

Information

Shared R&D + Innovation projects

Focus on extreme cold & hot temperature testing

Focus on extreme cold & hot temperature testing

Data from lab and field testing

Knowledge, insight and understanding

CAPEX OPEX Yield

100€/MWh (Target Dong Energy)

Drivers for wind energy R&D

100€/MWh (Target Dong Energy)

Drivers for wind energy R&D

𝑪𝒐𝑬 = 𝑪𝑨𝑷𝑬𝑿 + 𝑶𝑷𝑬𝑿

𝑨𝑬𝑷

Reliability

Reliability & Availability

Reliability means: ‘the ability of a system to perform a required function, under given environmental and operating conditions and for a stated period of time’ .

Downtime: lost revenue = 5.000-15.000 €/day

Teesside Offshore Wind Farm – January 2014





Transformers are key components in a wind farm

In the beginning: off the shelf distribution transformers failed Unusual duty cycle Environmental conditions

In the turbine: fire risks, leakage,

low frequency stress cast resin transformers, lightning, thermal stress,…

Technology matured by trail & error Offshore high voltage substation: Transformer failure: big financial impact No power production of wind farm (4,5 months - 1 year)

It takes time to reach a mature technology

It takes time to reach a mature technology

Brothers Wright – First flight 1903

Airbus – First flight - 2005

102 years of development

1991 First offshore wind farm (nearshore) 450 kW turbines 4.95MW farm

22 years of development

2013 One of the latest offshore wind farms 6.5 MW turbines 325MW farm

36 8 3 10

Technological evolution

Time-to-market = important

Technological evolution:

Optimization VS radical innovation

Nacelle installed transformer

Tower installed transformer

Platform installed transformer:

+36kV solutions – multi-MW

turbines

Reliability = Key

Maintainability = Key

How to increase resilience and

mitigate the Risk?

1) Design input based

on field experience and realistic requirements need for field data

Overview environmental loads on wind turbines

Overview environmental loads on wind turbines

Belgian North Sea: Standard Offshore turbines Operating spec. temperatures: -10°C …+40°C

Northern Baltic Sea: CCV offshore turbines Operating spec. temperatures: -30°C …+40°C

Pori Offshore 1 Wind Farm – Northern Baltic Sea Arctic conditions -35°C

Onshore cold climate turbine – Mongolia : -50°C during winter night

Offshore station – North Sea – extreme waves

Offshore station – North Sea – extreme waves

9

10

4

8

5

1

2

6

7

3 Vibration Signals

Fundamental vibration modes

24.06.14 36

Belwind Winf Farm – 45 km from shore – North Sea Installation Alstom 6MW Haliade prototype

Hot climate Wind Farm – temperature specification: +50°C Heat dissipation transformer, cooling drivetrain,…

Hot climate Wind Farm – temperature specification: +50°C Heat dissipation transformer, cooling drivetrain,…

Challenge: Wind turbines are installed word wide

Therefore, wind turbines are subjected to different environmental loads

Design classification with regard to different climatic sites

Corrosive environment

Humidity & Rain

Strong gusts & heavy wind loads

Wave impacts; low freq. vibrations

Vibrations due to wind loads

(Extreme) cold temperatures: -40°C; -45°C

Ice-rain & icing

Heavy wind loads

Snow


(Extreme) hot temperatures : +45°C; 50°C;

Sand & dust


Solar radiation

Offshore wind turbines CCV wind turbines HCV wind turbines

Which requirements?

1) Wintertime more good wind conditions

2) Fact by EON : wind turbines produce 11% more power at -10°C than at +20°C

Climatic class EN 60076-11:

C1, C2, C3*

Which requirements?

2014 – extreme temperature events

Canada (Saskatoon) January 2014: -49°C

Chicago January 2014: -30°C

North China February 2014: -46°C

Mongolia: -50°C

Sweden 16/01/2014: -30°C USA: Polar vortex

causes cancellations of turbine maintenance tasks - 2014

How to increase resilience and

mitigate the Risk?

2) Test and validate all components and the full system for all possible operating

conditions to find weak links

Also for extreme environmental conditions

Such conditions don’t occur often, but if they do they can have a big impact when not been taken into consideration

The Challenger disaster was caused by the failure of an "O-ring" seal in the solid-fuel rocket on the shuttle's right side. The seal's faulty design and the unusually cold weather, which affected the seal's functioning, allowed hot gases to leak through the joint”

Environmental testing of transformers:

Environmental testing of transformers

Climate chamber testing of transformers

Why such test?

Transformers used in wind farm are far more exposed to (extreme) cold and/or hot temperatures than ‘conventional power plants’ due to their geographic location and their location inside the turbine

Example extreme event = cold start-up: thermal stress mechanical stress

To mitigate risk: prototype test (over-stress test, fatigue test) to check for leakage, cracks, performance,…

Simulation VS testing field data needed, time-to-market plays a role

Requested by certification body or customer as proof of safe & reliable operations in all conditions


Challenge?

Hi-tech infrastructure needed to cope with such tests

Multi-MW trend & Dimensions

External Lab VS in-house (freq. of such tests?)

Extreme temperatures / cooling power


Focus cold climate – Liquid Filled transformers

Storage test at -40°C: check for leakages/cracks on seals, thin plated cooling fins, bushings, cables,…

Cold start-up test at -30°C:

Check leakage/ cracks due to brittle material in combination

with pressure increase (thermal & mechanical stress)

Check natural cooling performance of transformer liquid during cold start-up

Paper EWEA: Cold start of a 5.5MVA offshore transformer

Check leakage/ cracks due to brittle material in combination with pressure increase (thermal & mechanical stress):

Temperature influences the gas cushion (if used) and the liquid level of the transformer Internal pressure changes

The internal pressure and liquid level must stay within a certain range in order to guarantee optimal performance

Pressure peaks switch off transformer negative impact availability Pressure peaks brittle material exceptional mechanical stress

Worst case: interaction of the gas cushion/ liquid level can lead to negative impact on elasticity of the tank: unacceptable stress cracks & leakage risk

Mitigate this risk through simulation and testing





Check natural cooling performance of liquid during cold start-up:

A design verification test was needed to proof that there was sufficient internal cooling during cold start-up events as simulating such an event is difficult and complex.

Due to the higher viscosity at low temperature of the used cooling liquids, the natural convection cooling of the internal windings may be limited in such way that the initial losses generated inside the transformers windings cannot be evacuated fast enough RISK !

Approach -30°C Full load cold test on a 5,5MVA transformer




Focus cold climate – Cast Resin Transformer

Check for cracks at low temperature operations:

Thermal stress mechanical stress due to brittle materials.

OWI-Lab has set-up a partnership with HV-Lab KEMA Arnhem

to cope with cast resin transformer tests at extreme low temperatures: -40°C, -50°C, -60°C

Example guideline thermal shock testing cast resin

Climate classes defined by IEC 60076-11 Class C1: the transformer is suitable for operation at ambient temperatures down to -5°C. (Exposed for storage & transportation: -25°C) Class C2: the transformer is suitable for operation at ambient temperatures down to -25°C (Exposed for storage & transportation: -25°C, -30°C or -40°C) Class C3*: the transformer is suitable for operation at -40°C, -50°C or -60°C

(storage & transportation: -40°C, -50°C or -60°C)


Focus cold climate – Cast Resin Transformer

Power electronics

Variable wind patterns

Transformer windings

subjected to a rapid increase

of heat

In low temperature operations/

cold start-up sequence: brittle windings

(= additional risk)

Cracks partial discharge

in concentrated area which can

not be dissipated = RISK

CONCLUSION:

Reliability = key to wind energy (offshore)

Fast increasing technological evolution

Wind turbines are installed at extreme climatic sites

Field data is needed to optimize requirements

Advanced component and system testing is becoming important in the strategy to mitigate risks

Case studies with regard to transformers and climate chamber testing indicate the importance to do so

Thank you for your attention!

[email protected]

www.owi-lab.be/

www.sirris.be

@OWI_lab

Group: Offshore Wind Infrastructure

Application Lab (OWI-Lab)

http://www.owi-lab.be/



http://www.sirris.be/