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Transmission towers and power lines in agricultural fields.

High-Voltage Basics: The Backbone of the Power Grid

By Dr. Christian Ohler
26-06-2024 | 8 min read
Picture of two electrical engineers using a notebook computer standing at a power station to view the planning work by producing electrical energy at high voltage electrodes.

An introduction to high-voltage

Discover the building blocks of high-voltage systems that are powering the world.

Welcome to the Power Pulse podcast blog series, where we delve into the exciting world of energy.

The Power Pulse podcast’s brand-new season features the brightest minds in the industry as they examine the challenges, opportunities, innovations, breakthroughs, and sometimes serendipities, that have played a part in advancing the development of the power grid. Hear them demystify the fascinating workings behind one of the most impressive engineering feats of the modern era - the electricity grid. Plug in! We promise an electrifying experience with every new episode.

The high-voltage basics

Understanding the backbone of the power grid

The intricate network of power lines humming outside our windows is a testament to the invisible force that fuels our modern lives: electricity. But have you ever wondered how electricity travels such vast distances, and what unseen heroes make this possible?

Take Los Angeles in 1907. Poised for growth, its ambitions were limited by the reach of its existing power grid. Homes and businesses demanded more electricity, and the answer lay in distant hydroelectric plants in the western side of the Sierras. The solution was a technological marvel that became the world’s longest and highest voltage transmission line of the time. It was also the first transmission line to be entirely supported by steel towers. These towering giants, stretching across vast distances, became the arteries of a burgeoning city, exemplifying the transformative power of high-voltage technology.

Today, we delve into the fascinating world of high-voltage, the backbone of our power grids, and explore the key components that work tirelessly behind the scenes to ensure efficient and reliable energy delivery. 

To go on a journey of discovery from power plants to power socket, tune in to the second episode of the brand-new season of the Power Pulse podcast: The high-voltage basics

The building blocks of high-voltage systems

Imagine electricity as water flowing through a pipe. The wider the pipe, the more water (current) it can carry. However, wider pipes are also more expensive and impractical to build and maintain. This is where high-voltage comes in. By increasing the voltage, the same amount of power (the product of voltage and current) can be pushed through a thinner pipe, thereby minimizing losses during transmission over long distances. 

So, what is high-voltage? And what are the essential components of a high-voltage system? 

Our electricity supply at home has a voltage of 230 volts. However, overhead lines carry electrical energy at levels significantly higher than household voltages. This is because high voltages are more suitable than low voltages for the transmission of electrical energy. There is less loss of energy due to conductor resistance. 

  • Transmission lines: These high-voltage cables carry electricity over long distances. They are typically made of aluminum or copper conductors with insulating materials and suspended on high pylons for safety and to prevent flashover - a spark jumping to the ground. 
  • Transformers: These workhorses of the grid play a crucial role in voltage transformation. At the power plant, electricity is generated at a relatively low voltage. Step up transformers significantly increase the voltage for efficient long-distance transmission. Conversely, step-down transformers near consumption points reduce the voltage to safe and usable levels for homes and industries. Think of transformers as volume control for electricity.
  • Substations: The high-voltage substation is a critical component in the power system. It is the node or interconnecting point for electrical generation, transmission, and distribution systems. Substations are interconnected with each other, so that the power system becomes a meshed network. This increases the reliability of the power supply system, by providing alternate paths for flow of power to take care of any contingency, so that power delivery to the consumer is maintained and the generators can supply all the consumers. 

  • Switchgear: These are the guardians of the grid, ensuring safe and reliable power flow. They include various types of switches that can isolate specific sections of the grid for maintenance or during faults. The most critical component is the circuit-breaker, the "king" of switchgear. It acts like a high-tech fuse, interrupting dangerous short circuits in milliseconds, protecting the entire grid from cascading failures.

Air-Insulated Switchgear (AIS): This traditional equipment uses atmospheric air as a dielectric for phase to phase and phase to ground insulation.

Substations using air-insulated switchgear require a large land area to maintain safe distances between live components.

Gas-Insulated Switchgear (GIS)A more compact alternative, GIS is a metal-enclosed switchgear that uses a gas as the primary insulation between live parts and the earthed metal enclosure. The gas provides high dielectric strength, high thermal stability, and excellent arc quenching properties.

Discover how Hitachi Energy’s innovative GIS solution contributed to build a stronger power grid in in Saudi Arabia.

GIS is mainly used where space is limited, and reliability is essential.

GIS is mainly used where space is limited, and reliability is essential.

Applications of high-voltage in the energy sector 

Powering the arteries of the energy sector

The intricate network of power lines and substations that deliver electricity across vast distances relies heavily on high-voltage technology. It acts as the lifeblood of the energy sector, enabling a multitude of critical functions. Let's delve deeper into the diverse applications of high-voltage in today's energy landscape:

  1. Bulk power transmission: At the heart of high-voltage applications lies its ability to efficiently transmit large amounts of electricity over long distances. Power plants, including renewable sources like wind farms and solar parks, are often situated far from population centers. High-voltage transmission lines, carrying electricity at hundreds of thousands of volts, bridge this gap. This minimizes energy losses during transmission, ensuring a larger portion of the generated power reaches consumers.

  2. Grid integration of renewables: The rise of renewable energy sources like solar and wind presents unique challenges for the grid. These sources are intermittent, meaning their output fluctuates based on weather conditions. High-voltage transmission lines come to the rescue again. By enabling the transmission of surplus renewable energy from areas with high generation to regions with higher demand, they help balance the grid and integrate these fluctuating sources. This ensures a stable and reliable electricity supply even with the increasing dependence on renewables.

  3. Distribution networks: High-voltage transmission lines excel at long-distance journeys, but for final use in homes and businesses, the voltage needs to be significantly reduced. Substations play a pivotal role here. They contain transformers, stepping down the high-voltage from transmission lines to medium voltage for regional distribution networks. This medium voltage is further reduced to low voltage at local distribution transformers, making it safe for direct use by consumers.

  4. Enabling diverse power sources: High-voltage technology is not limited to traditional power plants. It plays a crucial role in integrating other forms of electricity generation into the grid. For instance, high-voltage connections are essential for harnessing the power of hydroelectric dams, often situated in remote locations. Additionally, advancements in technologies like concentrated solar power plants, which generate electricity by focusing sunlight onto a receiver, utilize high-voltage transmission for efficient power delivery.

  5. High-Voltage Direct Current (HVDC) Transmission: While AC (Alternating Current) is the dominant choice for high-voltage transmission, High-Voltage Direct Current (HVDC) technology offers advantages in specific scenarios. HVDC excels in long-distance transmission with minimal energy losses and enables interconnection between grids with different AC frequencies. This is particularly valuable for integrating large-scale renewable energy projects located far from consumption centers or connecting grids across national borders.

Conclusion: The future of high-voltage technology

The road ahead: sustainable high-voltage solutions

The future of high-voltage technology lies in sustainability. Traditionally, insulating and interrupting gases used in switchgear have greenhouse gas properties. Hitachi Energy is at the forefront of developing new technologies that minimize environmental impact. This includes finding alternatives to SF6 gas while maintaining the high performance and safety standards expected for high-voltage equipment.

As the energy sector embraces renewable energy sources and decentralization, high-voltage technology will continue to evolve. Advancements in areas like smart grids and HVDC technology promise even more efficient and reliable transmission, paving the way for a sustainable and interconnected energy future.

Furthermore, optimizing designs to minimize material usage and exploring innovative solutions like compact gas-insulated substations are crucial steps towards a more sustainable grid infrastructure.

In conclusion, high-voltage technology is the invisible force behind the reliable and efficient delivery of electricity that powers our world. By understanding the key components and applications of high-voltage systems, we gain a deeper appreciation for the intricate network that keeps our lights on and our industries humming. As the energy sector embraces a sustainable future, Hitachi Energy is committed to developing innovative high-voltage solutions that ensure a cleaner and brighter tomorrow.

For more insights, tune in to Hitachi Energy’s Power Pulse podcast and explore our range of high-voltage switchgear and breaker solutions tailored to enhance your operations.

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Dr. Christian Ohler
Head of Global Product Group Switchgear, High Voltage Products business unit, Hitachi Energy

Christian joined the company in 1998 in the Corporate Research Center, Switzerland, and has since gathered extensive experience in research and development, product development, and product management. A keen photographer with a curious mind, he firmly believes that it is how people collaborate within the company that makes the difference.

He holds a Ph.D. in semiconductor physics from RWTH Aachen.