The Grid is Not Homogeneous

We use the term “the grid” to refer to a monolithic power source that we plug into and run our world. Needless to say, that is not close to reality. The grid is a complex network of power generation, distribution, exchanges, co-ops, and management systems across land and sea. The old saying goes, “Use the right tool for the job.” This is true regarding bridging grids, off-shore power, mining, and other remote or edge power connectivity.

HVDC - Applications and Use Cases

High Voltage Direct Current (HVDC) technology, with its unique features, is increasingly adopted for specialized, high-impact applications where conventional AC transmission faces technical or economic limitations. HVDC's most prominent use cases include long-distance bulk power transmission, interconnecting asynchronous power grids, and integrating remote renewable energy sources such as offshore wind farms. These applications leverage HVDC’s ability to efficiently transmit large amounts of electricity over vast distances with lower losses and greater control than traditional AC systems.

One of the key applications of HVDC is its ability to interconnect asynchronous grids (e.g., the Eastern and Western U.S. interconnections) and minimize losses over long distances, making it critical for modern grids. HVDC is ideal for transmitting power from remote generation sites, such as hydroelectric dams or offshore wind farms, to urban centers that may be hundreds or thousands of kilometers away. It also enables linking power grids that operate at different frequencies or are otherwise unsynchronized, facilitating international energy trade and enhancing grid stability. Additionally, HVDC is used in back-to-back converter stations for grid interconnections and submarine cable projects where AC transmission is impractical due to reactive power constraints and cable charging currents. These advantages make HVDC a cornerstone technology for the modern, interconnected, and renewable-focused energy landscape. 

• Cross-Bridging Asynchronous Grids - Connects grids like the U.S. Eastern/Western interconnections and international links (e.g., the UK-France interconnector).

• Offshore Wind Farms - Transmits power from projects like Hornsea (UK) and Bhadla Solar Park (India) to onshore grids.

• Long-Distance Bulk Transmission - China’s 1,100 kV, 3,300 km Zhundong–South Anhui line delivers 12 GW.

• Urban Infeed - Supplies megacities with minimal land use (e.g., ±800 kV Xingu-Rio line in Brazil).

Active HVDC Deployments

These projects illustrate HVDC’s key roles in long-distance bulk power transfer, renewable energy integration, cross-border interconnections, and grid stability enhancements. Here are several notable examples of HVDC deployments from around the world, illustrating the technology’s versatility and growing importance in modern power grids:

• Quebec–New England Transmission (Canada/USA): Opened in 1992, this is the world’s largest multi-terminal HVDC system, with a capacity of 2,000 MW, allowing power exchange between the Canadian and U.S. grids.

• Pacific DC Intertie (United States): Completed in 1970, this was the first HVDC system in the U.S., enabling the delivery of hydropower from the Pacific Northwest to Southern California over approximately 1,360 km. It was later expanded to a capacity of 3,100 MW, helping balance supply and demand between regions with different peak times.

• Itaipu HVDC Transmission System (Brazil): Built to transfer power from the Itaipu hydroelectric plant to load centers near São Paulo, this 800 km bipolar system operates at ±600 kV and can transmit up to 6,300 MW, showcasing HVDC’s ability to handle high power over long distances.

• North Plains Connector (United States): Currently in development, this project will link the Eastern and Western U.S. power grids via a 600 kV HVDC line, enabling bidirectional power flow and grid flexibility.

• North Sea Link (Norway–UK): A 730 km subsea HVDC cable with a capacity of 1,400 MW, facilitating renewable energy exchange between Norway and the UK.

• Raigarh–Pugalur (India): A ±800 kV, 1,830 km HVDC link with a 6,000 MW capacity, connecting renewable-rich regions in central India to high-demand areas in the south.

• Western HVDC Link (UK): This 422 km, 600 kV subsea HVDC project connects Scotland and Wales, transmitting 2,200 MW and supporting the integration of renewable energy into the British grid.

HVDC vs. Standard Grids

Source: https://clouglobal.com/hvdc-transmissions-essential-role-in-modernizing-power-grids/

What is an HVDC System?

A High-Voltage Direct Current (HVDC) system transmits electricity using direct current (DC) at voltages typically ranging from 100 kV to 800 kV (ultra-high-voltage systems exceed 800 kV). Unlike alternating current (AC), which reverses direction cyclically, DC maintains a constant flow, enabling efficient long-distance power transfer. Key components include:

• Converters - Convert AC to DC (rectification) and DC back to AC (inversion) using thyristors (Line-Commutated Converters, LCC) or Insulated Gate Bipolar Transistors (Voltage-Source Converters, VSC).

• Transformers - Transform power between AC grids and DC systems, often designed to handle harmonics and DC voltage stress.

• Transmission lines - Overhead lines, underground cables, or subsea links.

• Control systems - Manage power flow, voltage stability, and grid synchronization.

• Capacitors - Provide voltage stabilization, harmonic filtration, reactive power management, and energy storage for instantaneous power management.

Why Use HVDC vs. HVAC?

HVDC (High Voltage Direct Current) transmission is chosen over traditional HVAC (High Voltage Alternating Current) for several compelling reasons, especially when transmitting large amounts of electricity over long distances or connecting asynchronous grids. HVDC systems experience significantly lower transmission losses compared to HVAC, as they are not affected by issues like the skin effect or reactive power losses that limit the efficiency and distance of AC transmission. This makes HVDC more cost-effective for long-distance bulk power transfer, typically beyond 500 km for overhead lines or 50 km for submarine cables, since fewer conductors and intermediate substations for voltage compensation are not required.

Additionally, HVDC offers several benefits over HVAC in specific scenarios. It enables the interconnection of power grids operating at different frequencies or otherwise unsynchronized, improving grid stability and allowing for controlled power flow between regions or countries. HVDC systems also offer enhanced controllability, allowing operators to manage the direction and amount of power transmitted precisely. This is particularly valuable for integrating renewable energy sources and balancing supply and demand across large, complex networks. While the initial investment in HVDC converter stations is higher, the operational savings and technical advantages often outweigh these costs. HVDC outperforms High-Voltage Alternating Current (HVAC) in specific scenarios, such as efficiency over long distances, asynchronous grid interconnection, offshore wind integration, and controllability.

1. Efficiency over long distances: HVDC losses are 30–50% lower than HVAC over 1,000 km due to reduced reactive power and skin effect. This efficiency is a testament to the robustness of HVDC technology, instilling confidence in its ability to deliver power over vast distances.

2. Asynchronous grid interconnection: HVDC links grids operating at different frequencies (e.g., 50 Hz and 60 Hz) without destabilization. This adaptability of HVDC technology in interconnecting grids of varying frequencies is a testament to its versatility and reliability.

3. Offshore wind integration: Subsea HVDC cables efficiently transmit power from remote wind farms to onshore grids. This efficiency in integrating offshore wind power into onshore grids using HVDC technology underscores its practicality and effectiveness.

4. Controllability: Precise power flow management enhances grid stability and resilience.

5. Breakeven Distance - HVDC is best for overhead lines (600-800km) and submarine distances up to 37km 

HVDC vs. HVAC 

Source: https://www.energy.gov/oe/articles/connecting-country-hvdc 

HVDC Requires High-Power & Temperature Capacitors

Capacitors in HVDC systems play critical roles in ensuring stability, efficiency, and power quality. Key applications include:

1. Voltage Stabilization - Capacitors smooth the DC voltage ripple generated during AC/DC conversion, maintaining consistent power flow to stabilize the DC bus voltage and mitigate transient fluctuations.

2. Harmonic Filtering - Converters (especially Line-Commutated Converters, LCCs) generate harmonics during operation. AC/DC harmonic filter capacitors absorb these distortions, preventing overheating and interference with grid equipment.

3. Reactive Power Compensation - LCC-based HVDC systems draw significant reactive power (~10–50% of active control). Shunt capacitor banks compensate for this demand, improving grid voltage stability.

4. Energy Storage for Rapid Adjustments - In VSC systems, capacitors store energy to support fast power flow adjustments, enhancing grid responsiveness during faults or load changes.

5. DC Ripple Reduction - Capacitors work with smoothing reactors to minimize ripple in the DC transmission line, reducing losses and preventing commutation failures.

NanoPlex - The 100% Plug-and-Play Upgrade for BOPP Capacitor Film

As the power grid transitions to a more dynamic, digital, and renewable-powered future, the demands on grid infrastructure - and the components that enable advanced control - are growing rapidly. HVDC systems require high voltage support, low dissipation factors and high levels of thermal stability to avoid de-rating. All rely on high-performance capacitor films to manage voltage, support reactive power, and maintain system stability under increasingly challenging conditions. Traditional capacitor films like BOPP (biaxially oriented polypropylene) are reaching their technical limits, especially as grid devices are required to operate at higher temperatures and under more stressful cycling.

Why NanoPlex LDF?

Peak Nano’s NanoPlex LDF is engineered as a 100% plug-and-play replacement for standard BOPP, offering a leap forward in performance and reliability for HVDC and the next generation of grid systems. Here’s why NanoPlex LDF stands out as the ideal capacitor film technology to support advanced grid modernization:

• 35% High-Temperature Operation - NanoPlex LDF operates continuously at 135℃ without de-rating, compared to BOPP’s 85℃ limit. This enables reliable performance in high-heat environments such as substations, converter stations, and power flow controllers where thermal stress is routine.

• Up to 5x Extended Lifespan - With a 5x longer operational lifespan under extreme conditions, NanoPlex LDF dramatically reduces maintenance needs and replacement cycles, supporting the long-term reliability required for critical grid assets.

• 50% Better Energy Efficiency - NanoPlex LDF delivers a 50% better dissipation factor than standard BOPP, translating to lower energy losses and improved efficiency in reactive power management-key for supporting the flexible, high-capacity operation of GETs.

• High Structural Stability - Virtually no film shrinkage occurs under 135℃ workloads, ensuring stable, predictable capacitor performance even during thermal cycling and grid transients.

• 100% BOPP Replacement  - As a 100% plug-and-play replacement for BOPP, NanoPlex LDF can be directly integrated into existing capacitor designs and manufacturing processes, minimizing transition costs and deployment timelines.

• 100% Secure, Domestic Supply Chain - NanoPlex LDF is US-manufactured with a 100% allied-nation supply chain, supporting grid resilience and national security as demand for advanced grid components surges.

By overcoming the temperature, efficiency, and reliability limitations of legacy BOPP films, NanoPlex LDF empowers utilities and OEMs to deploy HVDC systems at scale - unlocking more grid capacity, reducing congestion, and accelerating renewable integration. Its robust performance profile is particularly critical for advanced power flow controllers, dynamic line rating systems, and other grid devices that must operate in demanding environments without compromise. In short, NanoPlex LDF is the capacitor film foundation for tomorrow’s smarter, more resilient, and more flexible electric grid.

NanoPlex films also improve self-healing properties, mitigating dielectric breakdown risks during voltage spikes. By enabling higher power density and thermal stability, Peak’s technology supports HVDC deployments.

The Right Tool for the Job

When transmitting electricity over long distances, integrating renewables, or connecting grids operating out of sync, HVDC is the right tool for the job. Unlike traditional AC transmission, HVDC lines can move large amounts of power with far lower losses and fewer conductors, making them more efficient and cost-effective for bulk power transfer across hundreds or even thousands of kilometers. Their ability to precisely control power flow and connect asynchronous grids, such as those operating at different frequencies, makes HVDC indispensable for modern, resilient, and flexible energy networks.

HVDC is especially valuable in scenarios where AC transmission would struggle or prove uneconomical: undersea cable links, remote renewable energy integration, and cross-border interconnections are all where HVDC’s unique strengths shine. Its controllability allows operators to stabilize grids, manage energy trading, and respond rapidly to disturbances. This ensures reliable power delivery even as the grid evolves to accommodate more renewables and complex demands. In short, HVDC is not just an alternative, but the optimal solution wherever distance, efficiency, and grid compatibility are paramount.