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MerCo Publishing Inc.
525 Route 73 N, Suite 104
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Tackling interconnection challenges and constraints for U.S. offshore wind power

By Cathy Livingston and Salman Gill

With offshore wind projects in other parts of the world thriving, more energy firms are starting to get serious about exploring opportunities here in the U.S.

Onshore wind generation projects have already experienced success, but their effectiveness is limited by the large geographical distances between areas with favorable wind conditions in the Midwest and the large population centers on the east and west coasts, where most of the electrical load is located. Those markets are prime candidates for offshore wind power, but successfully executing a project in the U.S. is proving to be a challenging prospect, even for experienced European developers with multiple projects under their belt.

One of the main hurdles for those developers is overcoming interconnection issues. Interconnection and grid compliance can be consulted on during the very first phase of the Bureau of Ocean Energy Management's (BOEM) offshore wind energy program, but throughout the project development process, shoring up interconnection plans is necessary for local RTO/ISO feasibility and impact assessments. Accounting for the right technologies during the RTO/ISO process is crucial because solutions proposed are what may be required if the plan is approved. This process can take a year or longer, making it arduous for the developer.

Also specific to the U.S. market are the demands associated with the North American Electric Reliability Corporation Critical Infrastructure Protection plan (NERC-CIP), which consists of nine standards and 45 requirements covering the security of electronic perimeters and the protection of critical cyber assets, as well as personnel and training, security management, and disaster recovery planning.

Cybersecurity is a key component of NERC-CIP compliance, especially when leveraging digitalized assets that can be especially vulnerable without proper protection. As such, developers need to plan for multiple layers of defense embedded in substation automation and control system architecture. Those systems can be leveraged to save millions of dollars through remote access and management, as opposed to transfer of personnel to and from offshore installations, but require additional expertise to execute effectively.

Throughout the process, developers are challenged with the existing transmission system in the U.S., which was developed based on large centralized fossil fuel and nuclear-based power stations generally located away from the coast. The loads near the coastline are often at the very end of that transmission grid, and there are few existing substations capable of receiving and transmitting power from major new generation facilities offshore. Hence, interconnection and integration of large new offshore facilities into the existing grid is arguably one of the most critical aspects of the future success of offshore wind. For developers, it can also be one of the most difficult ones without in-depth knowledge of the U.S. grid infrastructure and the utility companies that support it.

To further complicate matters, there is no one-size-fits-all solution. Each project has its own unique challenges that must be addressed and integrated into the lengthy and complex regulatory approvals processes.

A prime example as it relates to interconnection is the decision between an AC or HVDC offshore substation. A critical objective at the early stage of project development is to select the most optimum technology for the interconnection of the planned offshore wind facility to the grid, and making sure that the power can be reliably delivered to the loads. For example, if a planned offshore wind facility is located far off the coast and appropriate interconnection points do not exist near the landing site for the export submarine cable(s), HVDC is a feasible alternative since siting of new overhead line corridors onshore will be problematic and risky, and an AC solution with long submarine and underground cable segments may not be able to deliver the power to the load due to the large reactive charging currents generated in long AC cable segments. With many more variables to consider when selecting the right option, developers are faced with a complex puzzle to solve.

When connecting offshore wind farms to power grids, developers also need to consider the project's ability to produce and transmit energy without impairing grid stability and reliability. Developers will often need to employ flexible AC transmission systems (FACTS), such as a static compensator (STATCOM) or static var compensator (SVC), which have proven their ability to increase the power transmission capacity of existing power grids where the grid connection is weak and short-circuit strength is low. By leveraging tools such as STATCOMs and SVCs, developers are able to make room for additional power transfer from wind farms over existing grids and instantly overcome a primary shortcoming of U.S. grid interconnection.

In the end, developers will face an array of interconnection challenges in the U.S. market, but intelligent solutions exist to make more offshore wind projects viable in the relatively untapped U.S. market. The result is a wealth of opportunity open to those armed with the right knowledge and tools to overcome the unique challenges and complex regulatory landscape of U.S. offshore wind power.

Cathy Livingston is Regional Market Manager, U.S. East, and Salman Gill is Global Business Development Manager, Power Consulting, ABB Power Grids.