1. ENG. Julius Ndirangu and
Challenges and Opportunities in Grid Integration of Offshore Wind Farms – A Review
Presenters
ENG. Julius Ndirangu and
ENG. STEPHEN NGULI
ORGANIZATION
Standards Department
KENYA POWER
Engineering Conference 2018

2. Engineering Conference 2018
Overview
Introduction
Design and Construction Considerations in Offshore Wind Farms
Opportunities in Grid Integration of Offshore Wind Farms
Challenges in Grid Integration of Offshore Wind Farms and Mitigation measures
Conclusion
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3. Engineering Conference 2018
Introduction
Ocean economy - the economic activities that take place in the ocean, receive outputs from the ocean, and provide inputs to the ocean.
Blue economy - sustainable ocean economy, where economic activity is in balance with the long-term capacity of ocean ecosystems to support this activity and remain resilient and healthy.
Causes of Rapid Growth in Renewable Energy Production
Rising cost of fossil fuels due to limited reserves
Increase in demand for electrical energy
Environmental issues caused by conventional sources
Reduced costs of renewable energy generation installati0ns
178 GW of renewable power generation capacity added in globally.
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Introduction cont…
Renewable energy sources from the ocean
Ocean thermal energy conversion (OTEC),
Wave energy,
Tidal energy
Offshore wind energy(OWFs).
Why OWFs ? (i)Reduced space for installation of wind farms on land
(ii) better energy production,
(iii)reduced turbulence intensity, higher capacity factor .
Currently, OWFs is visible in Europe & United States. Europe installed 16.8GW in net installed capacity to GW: 153 GW onshore and 15.8 GW offshore
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Introduction cont…
In 2005, it was found that Mozambique, Tanzania, Angola, South Africa and Namibia – have potentially large off-shore wind energy resources.
In Kenya, a Swedish firm, VR Holding AB in 2016 expressed interest in building a 600MW wind farm in the Indian Ocean( Ras Ngomeni in Malindi.)
Kenya government turned down the request citing (i)lack of a framework for renewable energy projects of that scale
(ii)Low demand for electricity in the country.
The investor moved to Tanzania
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6. Design and Construction Considerations in OWFs
An OWF comprises
offshore wind turbines,
a collector network system(2okV or 33kV),
a step up substation and a transmission grid.
Design and Construction considerations include:
1. OWF Installation - In the past fixed support platforms for wind turbine structures have been used.
Disadvantage is high frequency excitation due to rotating blades and tower flexibility causes resonance to occur at its natural frequencies( shorten their fatigue life when the water depth increases.)
Current trend is floating supported structures - have greater flexibility of construction and installation procedures and can be easily removed from the OWF system.
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7. Design and Construction Considerations in OWFs cont..
2. Power evacuation and Grid interconnection of Offshore Wind farms -
Power evacuation from the OWFs to the onshore grid system is through Medium voltage/High voltage AC system or through a HVDC transmission system.
Subsea AC power cables have a high capacitive shunt (less power transfer capability.
DC system is preferred but is significantly expensive because of AC/DC/AC conversion.
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8. Design and Construction Considerations in OWFs cont..
Typical layout of HVAC transmission system
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9. Design and Construction Considerations in OWFs cont..
Typical layout of HVDC transmission system
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10. Design and Construction Considerations in OWFs cont..
3.OWF control and operation- Static synchronous compensator (STATCOM) for reactive power compensation for voltage control at the wind farm. Classical voltage and frequency droop characteristic for balanced active and reactive power.
4. Protection and security of OWFs - protection zones are wind farm area, collection system, interconnection system and the utility area.
5. Grid code compliance for OWFs : limits on voltage, total harmonic distortion (THD) level at PCC, FRT capability, frequency and voltage control.
6.Condition and Structural Health Monitoring of OWFs - Condition monitoring (CM) information in utilities is utilized to detect incipient faults, and thus enable to perform more effective and efficient maintenance scheduling.
7.Economics and ecological considerations in OWFs -The cost of electricity from OWFs is influenced by economic depreciation, operation and maintenance cost, tax paid to authorities, energy storage components as well as the intermittency factor due to variation in wind speed.
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11. Opportunities in Grid Integration of Offshore Wind Farms
Wind is much faster, stronger and, steady over water bodies than over land, resulting in increased power potential and efficiency.
space availability in the ocean for installation of the turbines without interfering with populated areas.
OWFs provide renewable energy(no pollutants or GHG).
Employment in installation, operating, and maintaining offshore wind turbines than land-based ones.
Global commitment to renewables :- focus on the immense stores of energy in the ocean.
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12. Challenges in Grid Integration of OWFs and Mitigation measures
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13. Challenges in Grid Integration of OWFs and Mitigation measures cont..
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Conclusion
Design and construction considerations for OWFs have been reviewed.
Opportunities that stand to accrue from OWFs grid integration
Challenges in Grid Integration of OWFs and possible mitigation measures suggested.
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Recommendations
A pilot project to evaluate the viability of OWFs in Kenya through PPA to :-
Develop a test bed to gather operating experience.
Demonstrate technical reliability
Verify commercial feasibility
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End
Q & A
THANK YOU
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