HVDC vs. HVAC Power Cables in Onshore Wind Energy Transmission: Engineering Integration and Grid Stability Impact

In the evolving landscape of renewable energy, onshore wind farms play a crucial role in reducing greenhouse gas emissions and meeting global energy demands.

Integrating these farms into the transmission network involves intricate electrical engineering considerations, particularly when dealing with Balance of Plant (BoP) components, converter topologies, and power electronics.

Let’s explore how onshore wind energy is integrated into the grid, including the role of Battery Energy Storage Systems (BESS), and how this integration impacts power quality, grid stability, and planning.

A. Integration of Onshore Wind Energy into the Transmission Network

A1. Balance of Plant (BoP):

The BoP components for wind farms include infrastructure such as transformers, switchgear, and substations that connect wind turbines to the transmission network.

These components ensure that power generated by wind turbines is efficiently transferred to the grid while maintaining reliability and safety.

A2. Converter Topologies and Power Electronics:

Onshore wind farms typically use two main converter topologies—full-converter and doubly-fed induction generator (DFIG) systems.

Full-converter systems provide better control over power quality and grid compatibility as they decouple the generator from the grid. DFIG systems, while less costly, have a more complex interaction with the grid, potentially impacting power quality and stability.

A3. Power Electronic Interfaces:

These include inverters and rectifiers that convert the variable output of wind turbines into a stable AC voltage compatible with the grid.

The choice of power electronic devices and their configuration is crucial for optimizing performance and ensuring grid stability.

B. Integration with Battery Energy Storage Systems (BESS)

Battery Energy Storage Systems play a significant role in balancing the variable nature of wind energy. They store excess energy when production is high and release it when production is low, stabilizing grid frequency and voltage.

BESS can be integrated at various points within the wind farm or at the grid connection point, enhancing overall grid reliability and flexibility.

A Case Study of Horns Rev 3 Offshore Wind Farm in Denmark incorporates a sophisticated BESS to manage its substantial energy output. This integration has improved the stability and reliability of the grid by smoothing out fluctuations in wind power and providing frequency regulation.        

C. HVDC vs. HVAC Power Cables

C1. HVDC (High-Voltage Direct Current):

HVDC cables are used for long-distance power transmission and are more efficient than HVAC (High-Voltage Alternating Current) cables over great distances.

They also minimize transmission losses and are capable of transmitting power in a more controlled manner, which can be particularly beneficial for offshore wind farms.

C2. HVAC (High-Voltage Alternating Current):

While HVAC systems are more commonly used for shorter distances and are generally less expensive than HVDC, they suffer from higher losses and require more infrastructure for long-distance transmission.

D. Impact on Power Quality, Grid Voltage, Frequency, and Waveform

Integrating wind farms with the grid introduces harmonics and voltage fluctuations, which advanced power electronics can mitigate through careful design and tuning.

Wind farms and battery energy storage systems (BESS) contribute to grid stability by maintaining voltage and frequency levels while absorbing excess energy when needed. However, power electronics can cause distortions in the electrical waveform, impacting overall power quality.         

To address these distortions, proper filtering and control strategies are essential for maintaining waveform integrity. A well-designed integration of wind farms and BESS ensures reliable and efficient grid performance.

The integration of wind farms can alter grid impedance, potentially impacting the performance of other grid components. Managing impedance involves careful planning and real-time monitoring to ensure system stability.

E. Effective Planning with Oracle Primavera P6 and NEC4 Contract

Oracle Primavera P6 is a project management software that helps in scheduling, resource allocation, and risk management, ensuring efficient coordination across all phases of wind farm integration. Its effective use ensures that projects remain on schedule, from design to execution.

The NEC4 Contract provides a structured framework for managing risks, ensuring quality standards, and adhering to timelines throughout the project lifecycle. By facilitating clear communication and accountability among stakeholders, NEC4 plays a crucial role in enhancing project success.

Together, Primavera P6 and NEC4 contribute to streamlined and well-managed wind farm integration projects.

A case study of the Fosen Vind project in Norway and the Tres Amigas SuperStation in the U.S. shows the differing applications of HVAC and HVDC power cables for onshore wind farm grid integration. The Fosen Vind project, one of Europe's largest onshore wind farms, utilized HVAC (High Voltage Alternating Current) cables due to the wind farms' proximity to the grid. HVAC was chosen for its cost-effectiveness and simpler installation process, as the shorter transmission distances minimized energy losses, making it an ideal solution. Primavera P6 was crucial in managing the scheduling, resource allocation, and coordination of various stakeholders, ensuring the project remained on time and within budget. In contrast, the Tres Amigas SuperStation in the U.S. used HVDC (High Voltage Direct Current) technology to integrate multiple wind farms spread over vast distances. HVDC was selected for its efficiency in long-distance power transmission with reduced losses, which was essential for transmitting electricity across large geographical areas. The HVDC system also provided superior control over power flow, enhancing grid stability as more renewable energy sources were integrated. Primavera P6 was instrumental in coordinating the complex project phases, including risk management and resource planning, ensuring smooth collaboration among the engineering teams and timely completion of the project.        

These case studies highlight the importance of selecting the appropriate transmission technology—HVAC for shorter distances like in Fosen Vind and HVDC for long-distance transmission in Tres Amigas. Additionally, Primavera P6 played a key role in ensuring project success by managing timelines, resources, and stakeholder communication efficiently.

Recent innovations in wind energy integration include advancements in solid-state transformers and the use of AI for real-time grid management. These technologies offer improved efficiency, better grid control, and enhanced reliability.

What are your thoughts on the future role of HVDC technology in wind energy transmission? How do you think emerging innovations will shape the industry???

This post reflects my personal knowledge and is for educational purposes only.

#RenewableEnergy #PowerCables #OnshoreWindEnergy #HVDCPowerCables #PowerQuality #BESS #GridCodeComplianceStudies

Source reference:

Letcher, Trevor M. Wind Energy Engineering a Handbook for Onshore and Offshore Wind Turbines. London San Diego, Ca Cambridge, Ma Ap, Academic Press, An Imprint Of Elsevier, 2017

Orsted (n.d.).?Hornsea 1 Offshore Wind Farm. [online] orsted.co.uk . Available at: https://orsted.co.uk/energy-solutions/offshore-wind/our-wind-farms/hornsea1 .

?Fosen Vind Project, Norway, the Biggest Onshore Wind Farm in Europe. www.nsenergybusiness.com/projects/fosen-vind-project/ . Accessed 20 Sept. 2024.

Recommendations for the electrical and electronic equipment of mobile and fixed offshore installations, Institution of Electrical Engineers, 2nd. 1992

Power Engineering International. “Tres Amigas Superstation: A Landmark HVDC Project - Power Engineering International.” Power Engineering International, May 2011, www.powerengineeringint.com/news/tres-amigas-superstation-a-landmark-hvdc-project/ . Accessed 20 Sept. 2024.