High-voltage direct current (HVDC) transmission systems are vital to the transition to renewable energy, enabling efficient power transmission over long distances. However, maintaining grid stability and power quality presents significant challenges in both offshore and inland power transmission networks.
Our capacitor films are one of the essential components enabling the effective functionality of HVDC transmission systems, either in the form of valve capacitors during the conversion of energy or various filter capacitors ensuring system stability and performance.
The growth HVDC transmission systems
HVDC technology has become a key component in modern power grids worldwide, serving as the backbone for efficient energy transmission across both land and sea. By the end of 2023, global offshore wind capacity had reached 75 gigawatts (GW), making it a significant part of the world’s energy mix. China is leading the development with 129 operational offshore wind farms, followed by the United Kingdom, Germany, and Vietnam.
The future outlook is promising, with forecasts suggesting that offshore wind capacity will continue to grow substantially by 2030. However, HVDC systems are not limited to offshore applications—they are increasingly used for effective inland transmission alongside HVAC systems, particularly for longer distances where HVDC offers superior efficiency, lower losses during the transmission and in general better economy of installation costs.
This growth is driving high demand for efficient and reliable components, including capacitors used in HVDC systems, which are essential for energy transmission and maintaining grid stability across the entire power network.
The critical role of capacitors in HVDC systems
Capacitors play a fundamental role in the functionality and effectiveness of HVDC systems in several key ways:
Energy conversion-voltage stability: Capacitors help in general to stabilize the electrical voltage. In the HVDC architecture the DC voltage needs to be maximaly stable at generating converted side where the power is made ready for the transport, in a same way on the receiving converter station the capacitors support the stabilty of the energy delivered into the power grid.
Valve and DC-link capacitors are essential components in the conversion stations providing such a functionality. Out of providing the principal functionality for conversion process these specialized capacitors maintain the quality and stability of transmitted electrical power what ensures the reliable operation of the HVDC system, protects connected equipment and supports the stability of connected subsequent power grids and infrastructure.
Filtering: HVDC converters generate duirng the operation the harmonic noise, which can distort the voltage and current waveforms with a subsequent degradation of the quality of transmitted energy and not in a last row also creating the risks for HVDC network components. Filter capacitors eliminates these harmonics and this way maintain power quality and reducing losses of trasmitted energy.
Reactive power management: Depending on the HVDC system architecture capacitors need also to contribute to reactive power compensation what is one of the necessary part of the quality energy transfer.
Applications – Tervakoski Films’ capacitor films in HVDC systems
The power capacitors used in the grid structures are required to be the highest quality, providing excellent durability and reliability to ensure the safe electric network functionality over decades.
Film capacitors are the preferred technology for HVDC applications due to their combination of reliability, performance, and safety features. Modern HVDC systems primarily use metallized polypropylene film capacitors, which offer out of other aspects a crucial safety advantage through their self-healing property. This feature allows the capacitor to continue functioning even after minor breakdowns, significantly enhancing system reliability and safety compared to older oil-impregnated designs.
Tervakoski Films’ metallised capacitor films proved their safety and extreme reliability in
the HVDC installations in a global scale. Our focus is on delivering films that maintain consistent performance under challenging conditions, including high voltage stress and temperature variations. The tools we use to deliver this promise are high quality raw materials in combination with state of the art manufacturing technology and high quality manufacturing process adapted to the specific requirements of the films for HVDC applications.
Our capacitor films support HVDC transmission systems across various energy sources:
Power transmission networks: Our films are used in HVDC systems that form the backbone of modern power grids, connecting energy sources to consumption centers across long distances.
Renewable energy integration: Whether for offshore wind farms, large solar installations, or hydropower projects, our capacitor films help ensure stable and efficient power transmission.
Grid interconnection: HVDC systems using our films help connect asynchronous grids and strengthen existing power networks.
The future of capacitors in HVDC systems
As HVDC technology continues to evolve, capacitor requirements are also changing.
We can identify several challenges that capacitor films are likely addressed by engineers working on the evolution of the HVDC systems:
Higher energy density requirements: System designers are continuously working to reduce the size and weight of components, driving the need for capacitor films that can safely store more energy in smaller volumes.That goes hand by hand with the need to withstand increased voltage stress accross the layer of capacitor film.
Temperature stability: The potential adoption of wide bandgap semiconductors (such as SiC-based components) may introduce higher temperature stress, requiring films with enhanced thermal stability. In a same way actual need for additional cooling of capacitors might become to be revised when using the capacitor films capable to withstand higher operating temperatures.
Enhanced reliability: As HVDC systems become more critical to power infrastructure, the demand for even greater reliability and longer service life is permamnentlyl increasing.
Tervakoski Films Group invests in continuous development to respond with the film performance to the challenges and meet these evolving needs. This commitment to innovation ensures that our films remain at the forefront of HVDC capacitor technology while maintaining the highest standards of safety and reliability.