Transmission & distribution |
integrating increasing amounts of renewable energy into the grid.
Figure 2. Envelope for VSC Compliance. Source: SSEN Transmission/National HVDC Centre
return (DMR) in the long HVDC section between the DCSS and the south England terminal, a hybrid rigid-DMR earthing arrangement is proposed. This innovative approach eliminates earth current without compromising the power transfer capacity of the residual terminals. Real-time digital simulation. The project utilises RTDS to simulate and test the HVDC network under various operating conditions. This enables the identification and mitigation of potential issues before they occur in the real world.
Interoperability testing. Extensive interoperability testing is conducted to ensure that different vendors’ equipment can work together seamlessly. This includes testing for compatibility in control strategies, communication protocols, and fault management.
Generic modelling and specification. The development of generic models and specifications for HVDC systems provides a standardised approach to system design and integration. This ensures that all components can work together effectively, regardless of the manufacturer.
Advanced control functions. Control development focuses on creating advanced control functions that can manage multi- terminal environments effectively. These functions are crucial for maintaining system stability and reliability under various operating conditions.
Collaboration with vendors and TSOs. The project engages with the vendors and TSOs to ensure the approach is robust and meets industry standards. This collaboration is essential for developing a comprehensive and effective interoperability framework. Real-time joint simulations. Demonstrations involve real-time joint simulations to prove the interoperability of multi-vendor systems. These simulations ensure that performance can be monitored and controlled effectively, providing confidence in the system’s reliability.
International context and interoperability initiatives The Aquila Lite project is not an isolated effort. Similar initiatives are underway globally, notably
in the EU and China. The EU-funded “Enabling interoperability of multi-vendor HVDC grids” (InterOPERA) project aims to define the technical frameworks that can ensure HVDC systems or components supplied by different suppliers work together, as an enabler for the deployment of 300 GW of offshore wind by 2050 to meet climate targets.
China’s State Grid Corporation has been developing multi-terminal HVDC systems to enhance grid reliability and efficiency in transmitting bulk renewable power. These international efforts highlight the importance of interoperability in HVDC systems, as they enable the integration of renewable energy sources and improve grid resilience.
Expected outcomes and benefits The expected outcomes of the Aquila Lite project include reducing the number of required AC converter stations, leading to significant economic and environmental benefits. Also, by encouraging innovation and competition in the HVDC market, the project aims to enhance the reliability and efficiency of future HVDC networks. The Aquila Lite project has several significant implications for future energy projects: Enhanced interoperability. By proving that HVDC systems from multiple vendors can work together seamlessly, the Aquila Lite project sets a precedent for future projects. This interoperability reduces dependency on single vendors, fostering a more competitive and resilient market. Increased reliability. Multi-vendor systems enhance the reliability of HVDC networks. If one vendor’s system encounters an issue, other systems can continue to operate, reducing the risk of outages and improving overall grid stability. Cost efficiency. The project demonstrates that fewer AC converter stations are needed, which can lead to significant cost savings. The hybrid earthing scheme also reduces the need for expensive dedicated metallic returns, further lowering costs. Scalability. The successful demonstration of multi-vendor interoperability in a lab environment provides a scalable framework that can be applied to larger, more complex HVDC networks. This scalability is crucial for
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Innovation and competition. By encouraging multiple vendors to collaborate and compete, the project drives innovation in HVDC technology. This can lead to the development of more advanced, efficient, and cost-effective solutions for future energy projects. Global standards. The project contributes to the development of global standards for HVDC systems. These standards are essential for ensuring that HVDC technology can be widely adopted and integrated into different energy markets around the world. Environmental benefits. By facilitating the integration of renewable energy sources like offshore wind, the project supports the transition to a low-carbon energy system. This is a critical step towards achieving global climate goals and reducing greenhouse gas emissions.
Commercial frameworks. The development of supporting commercial frameworks for multi-vendor interoperability can streamline the procurement and implementation processes for future projects. This makes it easier for energy companies to adopt HVDC technology and realise its benefits.
Innovation and collaboration The Aquila Lite project paves the way for more flexible, reliable, and cost-effective HVDC networks, and is a testament to the power of innovation and collaboration in overcoming technical challenges. Through close collaboration with global HVDC suppliers, SSEN Transmission and the National HVDC Centre have successfully developed technologies to enable the seamless operation of multi-vendor HVDC systems, which is essential for the future of renewable energy integration and grid modernisation. This project is a significant step towards creating a sustainable and resilient clean energy system for the future – by addressing the challenges of multi-vendor interoperability, the project sets a precedent for future HVDC developments worldwide.
Figure 3. A multi-terminal multi-vendor HVDC simulation was presented at the March 2025 Institution of Engineering and Technology (IET) AC/DC conference. Source: SSEN Transmission/National HVDC Centre
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