Black Start capability in the Wind Turbine Market

Transcription

1 Black Start capability in the Wind Turbine Market Jamie Thomson / Ian Talbot 10 th January 2018

2 Introduction to the Project The Offshore Wind Accelerator (OWA) is a collaborative R&D programme between The Carbon Trust and 9 wind farm developers. Their aim is to reduce the cost of offshore wind as well as providing insights regarding industry standard health and safety requirements. Frazer Nash Consultancy were contracted to assess the cutting edge developments in existing and new black start solutions for offshore wind turbines. 2

3 Project Description Work Package 1: Technology and Market Review A review of the market was completed to determine new black start technologies. Work Package 2: Workshop Consultation An open meeting to discuss the report, the future market needs and steps required to move the market forward. Work Package 3: Risks, gap and cost-benefit analysis A cost benefit tool was developed to determine the most cost effective method of black starting a wind turbine. 3

4 What is Back Start?? Depends on where you sit in the supply chain Network operators think of it as restoring the grid system when there has been a major system disruption, cutting off some or all of the network Wind farm operators think of it as energising the platform and wind farm when the grid connection is lost and powering the auxiliaries until the connection to the onshore grid is restored. WTG manufacturers think of it as powering the auxiliaries in each individual turbine when there is no grid connection via the windfarm. 4

5 Existing Solution G Offshore Substation Export Cable Onshore Existing solution to black start Offshore Wind Farms use Diesel generators on the platform to source all energy. (These can also be in the turbines) Proven Technology. Expensive Operating Costs. Significant CO 2 emissions Cannot provide power to the onshore grid.

6 Black Start Stages Stage 1 G Offshore Substation Export Cable Onshore The most basic form of black start uses a turbine able to Black Start itself and power its auxiliary functions. The platform no longer powers the array cables to feed the turbines. A much smaller diesel generator will still be required on the offshore platform to power essential service functions. Most turbines are already capable of delivering this solution. 6

7 Black Start Stages Stage 2 G Offshore Substation Export Cable Onshore A greater challenge is for the turbines provide the reactive power to energise the inter-array cables. The controls for the turbine and internal converter need to be developed to operate in a weak grid. A limited number of WTGs then Black Start an islanded string of turbines. A diesel generator is still required to energise the offshore substation. 7

8 Black Start Stages Stage 3 Offshore Substation Export Cable Onshore It is a relatively easy step for the turbines to black start the platform, with the inductance of the transformers offsetting the capacitance of the cable. The bock loading of the turbines need to be confirmed to energise the transformer The requirement for a diesel generator has now been removed. A UPS system will be used to provide auxiliary power in times of low wind. 8

9 Black Start Stages Stage 4 Offshore Substation Export Cable Onshore The challenge is for the turbines to provide the reactive power to energise the much bigger block of the main export cable. There is no diesel generator in this option. This solution would potentially be able to provide power into a weak grid since the wind farm is being energised from the turbines. 9

10 Black Start Stages Stage 5 Offshore Substation Export Cable Onshore The final stage is what Network Operators call Black Start, where the wind farm would be able to provide power into the onshore grid network. Needs to meet Grid Code requirements for block loading, voltage control, frequency control, etc This is the most technically demanding black start solution. Significant work would still be required to make this technically feasible. 10

11 Work Package 1 Literature Review Literature Review The only publically available manufacturer document was a technical note from ABB on their PCS6000 converter. Patent Review A worldwide patent search discovered 12 patents in the last 10 years Most of the major wind turbine and component manufacturers were represented. Journal Review Journal searches were carried out on the IEEE Xplore digital library and ScienceDirect. Three journal articles were discovered regarding islanded operation and VSC-HVDC control systems 11

12 Work Package 1 WTG Manufacturer Review Potential Black Start Solutions Major OEMs are developing variants of a similar system. The turbine operates in an islanded mode and generates its own auxiliary power. Auxiliary power is tapped off in the Rectifier/Inverter stage of the turbine. A UPS can provide power during times of low wind. 12

13 Work Package 1 Alternative Technology Other renewable generation were considered Solar Cells Could provide some power however the area of the nacelle is too small. Max generation could be approximately 3kW. Not available at night or in poor weather Wave Energy This is already being developed. It remains at a low technology readiness level. It could provide enough power to help with black starting the turbine. Approximately 100kW output Turbines still have to be developed to operate in weak grid 13

14 Work Package 3 Cost Benefit Analysis A cost model was developed to determine the relative costs of each black start solution. The model works on relative costs vs base case of existing diesel generators. Reliability, availability, the local wind profile and accessibility are taken into account. All the WTG solutions and the Alternative Technologies worked out cost effective against Diesel Generators 14

15 Work Package 3 Conclusions Wind Turbines can provide black start services for themselves. They are close to being able to power the offshore platforms There are some potential gaps with regards to National Grid requirements. Block Demand Repeat Starts Wind Energy Availability Reactive Power All of the options explored are cost effective compared to the option of standby diesel generators. 15

16 Jamie Thomson, Senior Engineer / Ian Talbot, Principal Consultant j.thomson@fnc.co.uk / i.talbot@fnc.co.uk /