More than 80 countries have policies to promote power generation from renewable energy sources. Renewables like wind and solar vary over time. This can pose a significant risk to security of power supply when these power sources exceed some 10-20% of electricity demand, depending on power system flexibility (generator mix) and interconnections.
Significant challenges can occur when renewable energy output is ramping down while load is ramping up (and vice versa) and when wind power plants are shut down during storms. A high penetration of other distributed energy sources adds to the complexity.
Leveraging in-house wind and solar expertise
DNV delivers transmission and distribution (T&D) consulting services to investor-owned and public power utilities and power generation projects, with special emphasis on renewable energy integration and grid interconnection. By leveraging in-house wind and solar expertise, we bring a unique combination of skills to renewable energy projects from development through implementation.
Being at the forefront
DNV is investing heavily in research on how to secure power supply while mitigating climate change. One issue being approached is the challenge to store surplus energy from variable-output renewable energy sources and release that energy during peak demand periods, while other areas include offshore transmission grid and subsea power systems for the oil and gas industry. Utilising DNV’s in-house expertise on hydro power, we can support developments of pumped hydro storage. DNV has also performed research in Smart Grids, Compressed Air Energy Storage (CAES) and batteries as well as new methods of assessing performance of complex power systems.
Integration approach and customer benefits
Strategic Value Analysis
Strategic Value Analysis (SVA) is a methodology to strategically locate new renewable technologies close to transmission “hot spots” or congestion zones to improve transmission reliability while meeting the target renewable penetration levels.
By using a Geographical Information System (GIS), locations can be found where renewables can provide transmission benefits by reducing overloads and also prioritise the renewable location. Resource adequacy, planning reserves and ancillary services can also be evaluated.
The SVA can:
- Evaluate the costs and grid impacts of bringing renewables into the electricity system while addressing renewable penetration targets
- Act as a transparent and common methodology for renewable energy developers, utilities and affected agencies to evaluate magnitudes, locations and impacts or benefits of renewables being used to meet renewable targets
- Provide information that may be helpful to renewable developers and utilities involved in assessing “least-cost, best-fit” approaches to selecting renewables to meet renewable targets
- Benefit from perspectives, datasets and information being developed by study groups
- Be a useful tool in identifying potential transmission congestion and problems that may occur as renewable penetration increases, and in finding ways to help reduce or mitigate those problems.
Intermittency Analysis
Intermittency Analysis (IA) is scenario-based studies to examine region-, state- or country-wide system impacts of higher levels of intermittent renewables on the transmission grid. The analysis provides a framework for operators, utilities and planners to gauge the needs of the future electric power system.
The SVA is expanded to analyse the intermittency of resources on the transmission reliability through time sequential power flow analysis. The methodology analyses the correlation of intermittent resources by region and load to determine the impacts to reliability. The duration and magnitude of
transmission outages under contingency analysis can be evaluated to determine the proper solution (upgrading, curtailments or remedial action schemes).
Transmission expansion requirements
Based on SVA and IA, transmission expansion requirements for development of renewable zones can be determined. By analyzing renewables zones, “least regrets” transmission plans can be developed that provide reliability while meeting renewable targets. This allows agencies and utilities to prioritize transmission expansion. The goal is to determine where new transmission expansion and environmental studies should be concentrated so that, regardless of the exact location of the renewable development, major transmission would be constructed and available for renewable resources.