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Hitachi Energy’s HVDC Transformers guarantee uninterrupted power supply in South Africa
Customer Success Story

Hitachi Energy’s HVDC Transformers guarantee uninterrupted power supply in South Africa

In the pursuit of a sustainable future, the leading role of grid expansion cannot be overstated. To reach net-zero emission targets, nations are channeling resources into expanding electricity generation and modernizing infrastructure on a global scale.

HVDC as a key enabler for a carbon-neutral energy system

HVDC (High-Voltage Direct Current) technology stands out for its remarkable efficiency in transmitting substantial power over long distances and catering to specialized applications. As a key enabler for a carbon-neutral energy system based on renewables, HVDC is shaping the grid of the future.

Hitachi Energy has been a leader in this field since the 1950s, continuously evolving this technology to meet the demands of a dynamic energy ecosystem.

In pursuit of constant innovation for a sustainable energy future, Hitachi Energy has developed Ultra-High-Voltage (UHV) technology as an advancement of HVDC, designed to transmit massive power with minimal losses and integrate renewables. Picture wind farms in remote deserts seamlessly feeding energy-hungry metropolises—Hitachi Energy makes it happen*.

Countries worldwide are investing in generating more electricity and expanding their existing infrastructure. HVDC projects are the rising stars, connecting newly generated energy to the most demanding areas of our planet.

South Africa is no exception. Its expanding infrastructure demands large investments to generate new energy and distribute it efficiently throughout the region.

*Hitachi Energy has successfully developed and tested 1 100 kV converter transformer technology, breaking the record for the highest DC voltage levels ever. 


Grid expansion toward net-zero

As part of South Africa’s grid expansion and strengthening plan, two massive HVDC power lines connect Apollo Substation (near Pretoria in South Africa) to Songo (near Cahora Bassa Dam in Mozambique).

The HVDC power from Cahora Bassa flows through these lines, is converted to AC power, and is integrated into Eskom’s national power grid via the Apollo inverter station.

The Apollo – Songo HVDC line is approximately 1414 km with a single PLC repeater station at Pietersburg. The section of the HVDC line length from Pietersburg to Songo covers approximately 1146 km, making it one of the longest PLC links in the world.

Hitachi Energy collaborates with Eskom to support South Africa’s infrastructure expansion. Amid the global surge in energy infrastructure development, component manufacturers like Hitachi Energy support their customers in finding optimal solutions, considering timing requirements and the massive production demands that impact the delivery periods of products like transformers.

A certainly common challenge in such a market scenario is dealing with emergency situations in the event of a breakdown when the production of new units cannot be executed rapidly. Spare units play a crucial role in such conditions, ensuring uninterrupted operations.

Hitachi Energy's Solutions

Back-up transformers for enhanced grid reliability

Specifically for the Apollo Converter Substation in Johannesburg, Hitachi Energy has supplied three 90.8 MVA HVDCs, a critical component of the Cahora Bassa/Apollo HVDC scheme. As a key hub within the national grid, the Apollo substation interfaces seamlessly with both the 400 kV and 275 kV networks.

Delivered in January 2024, these three transformers serve as backup units. During breakdowns or maintenance, they step in without disrupting operations to ensure an uninterrupted power supply. As the older transformers retire, these new units will take over the critical task of converting 533 kV DC to 275 kV AC. Their mission: connect clean, renewable energy to industries and communities, providing stability to the grid.

The flawless execution of this project owes much to meticulous planning, vigilant oversight, and continuous monitoring at every stage during the entire design phase, right up to Factory Acceptance Testing (FAT) compliance. Each HVDC transformer is meticulously designed to precise client specifications, adhering to the highest engineering, quality, and sustainability standards.

Our long-standing partnership with the Apollo Substation underscores our commitment to providing advanced transformers for uninterrupted power supply in the country. Together, we facilitate the seamless integration of renewable energy into the national grid. 

From Design to Deployment: A Journey of Precision

The journey from design to delivery exemplifies precision and dedication. Here’s how it unfolds:

  1. Detailed Design Specifications: We subject the design specifications to rigorous electrical and mechanical reviews before production begins. This ensures that every transformer aligns perfectly with the customers’ requirements and regulatory standards.
  2. Critical Factory Acceptance Testing (FAT): Each transformer undergoes thorough testing to verify its compliance with design specifications. These tests guarantee reliability and performance.
Benefits and Impact

Enabling South Africa's clean energy future

Apollo Converter Substation has a strategic importance for the national grid. As a trusted partner of our customers, it is our duty to help them ensure a continuous energy supply throughout the country.

It is not the first time that Hitachi Energy has supplied products for Apollo Substation, underlining a long history with its customers characterized by adherence to stringent manufacturing and installation standards.

Together with our partners, we are steering South Africa toward a sustainable energy future—a future where reliable, clean energy effortlessly serves industries and communities.

“HVDC technology stands out for its remarkable efficiency in transmitting substantial power over long distances and catering for specialized applications. As a key enabler for a carbon-neutral energy system based on renewables, HVDC is shaping the grid of the future,” comments Abel Gilbert, South Africa Mar-ket Manager of Hitachi Energy Transformers Business.

HVDC converter transformers

Hitachi Energy offers HVDC converter transformers, which are the heart of HVDC transmission systems. Hitachi Energy has developed the world´s first 1100kV transformers to UHVDC link in China.
HVDC (high-voltage direct current)

High-Voltage Direct Current (HVDC)

Hitachi Energy pioneered HVDC technology almost 70 years ago. As a key enabler in the future energy system based on renewables, HVDC is truly shaping the grid of the future.
Hitachi Energy Power Transformers


Hitachi Energy offers distribution and power transformers, Dry-type and EconiQ™ Transformers as well as services, for industrial and commercial applications.