What are high voltage substations?

High voltage substations are facilities in the power grid that transform, control, and distribute electricity. They step up or step down voltage for efficient transmission and safe distribution, manage switching operations, protect the grid from faults, and ensure reliable power delivery to consumers.

How does a high voltage substation work?

A high voltage substation works by using transformers to step up or step down voltage, switchgear to control power flow, and protective devices to safeguard the grid. It regulates and monitors electricity, ensuring efficient transmission and safe distribution to end users.

What are the main components of a high voltage substation?

The main components of a high voltage substation are transformers (for voltage changes), circuit breakers and disconnect switches (for protection and isolation), busbars (for power distribution), instrument transformers (for measurement), surge arresters (for overvoltage protection), and control systems (for monitoring and automation).

How do high voltage substations differ from medium voltage substations?

High voltage substations handle electricity at much higher voltages (typically above 100 kV) for long-distance transmission, while medium voltage substations operate at lower voltages (1 kV to 100 kV) for local distribution. High voltage substations focus on efficiency and transmission, while medium voltage substations serve end-user needs closer to consumption points.

What is a hybrid substation?

A hybrid substation combines traditional air-insulated switchgear (AIS) and compact gas-insulated switchgear (GIS) technologies. It optimizes space, reduces costs, and enhances reliability by using GIS components for critical areas while keeping AIS for less space-constrained parts.

What is the difference between a substation and a power station?

A substation regulates and distributes electricity within the grid, adjusting voltage levels, while a power station generates electricity from energy sources like coal, gas, or renewables. Substations do not produce power; they manage its transmission and distribution.

High-voltage substations

Infrastructure facilities, industry, and private households around the world require more and more electrical energy. High-voltage substations, the node points of today’s complex power transmission infrastructure, play a key role in meeting this demand safely and reliably. Wherever you are, Siemens Energy is your reliable partner for planning and construction of customized, state-of-the-art high-voltage substations.

GIS 8DQ1-6 outdoor Santa Maria de Grado, Spain

Siemens Energy provides the entire range of services, technologies, and components that are required for the successful construction and operation of a high-voltage substation of any type. It is up to you to select from a comprehensive range of available services:

Concept, planning, engineering
Project execution including project management and manufacturing of all key components
Commissioning
Service and maintenance, refurbishments, upgrades, dismantling of old equipment
Financing

Siemens Energy helps industry customers focus on their core business by supplying fast, reliable, complete solutions that are based on a high degree of flexibility, continuous development, and outstanding consulting expertise for all steps of a high-voltage substation project:

Concept, planning, engineering
Support in grid code compliance as well as in handling and processing official planning documents and approval procedures
Project execution including project management and manufacturing of all key components
Commissioning
Service and maintenance, refurbishments, upgrades, and dismantling of old equipment
Financing

Reliable, proven, cost-efficient

Substations with air-insulated switchgear

Siemens Energy high-voltage substations with air-insulated switchgear (AIS) are the cost-efficient choice for rated voltages of up to 800 kV. They are renowned for highest reliability, economical operation, and low maintenance requirements.

The Siemens Energy experts always consider the electrical parameters as well as the environmental conditions to which a substation is exposed. That’s why Siemens Energy AIS substations meet even the most demanding challenges and provide:

an optimum solution when space restrictions and environmental circumstances are not an issue
easy implementation of a wide range of standard applications
reliable switching for up to 800 kV, rated currents of up to 8,000 A, and short-circuit currents of up to 80 kA

Compact, powerful, adaptable

Substations with gas-insulated switchgear

Siemens Energy high-voltage substations with gas-insulated switchgear (GIS) are ideally suited to meet some of today’s most important requirements: bringing power on high-voltage levels right into the centers of urban areas. With almost 50 years of GIS manufacturing experience and the largest installed base of GIS, Siemens Energy is able to provide GIS solutions that even comprise operational training.

More than 34,500 Siemens Energy GIS bays are currently in operation in GIS substations all over the world – even in most challenging environments. The comprehensive range of GIS for rated voltages from 72.5 kV to 550 kV provides ideal solutions for indoor and outdoor switching applications up to the highest performance rates that require:

a small footprint
outstanding reliability
very low noise and electromagnetic emissions

Modular, versatile, clever

Mixed technologies substations

Mixed technologies substations – or hybrid substations – are mainly used for the refurbishment and expansion of substations with air-insulated outdoor and indoor switchgear, particularly in cases when such modifications need to be accomplished with the substation in service. As space and time are main cost factors in the expansion of substations, solutions with Siemens Energy highly integrated switchgear (HIS) provide the possibility to quickly adapt a substation to today’s demands. The space-saving HIS circuit breakers, disconnectors, grounding switches, and instrument transformers are housed in pressure-resistant, gastight enclosures and require no additional space. Busbars and bushings originate in conventional AIS technology.

Mixed technologies substations are:

ideally suited for new substations when space is limited
outstandingly compact thanks to the hybridization of GIS and AIS technology
clearly structured, with good access to all equipment
modular to suit virtually any network concept

Flexible, robust, plug and play

Prefabricated power solutions increase grid development agility and resilience

Siemens Energy's prefabricated power solutions are an ideal plug and play solution when it comes to achieving urgent grid connection, renovation, or expansion in challenging environments. Their mobile and modular design allows to take up the challenge of tight construction timeframes, natural disasters, and operational restrictions. They ensure maximum flexibility of design and utilization, excellent reliability, and a high return on investment thanks to:

fast installation, small footprint, and easy relocation
minimum interface management, full pre-commissioning prior to dispatch, and little on-site work
robustness to transportation and handling constraints, as well as harsh environments

Public Service Electric and Gas Company SE&G | Bergen substation, USA This project broke records in terms of scale and performance. Gas-insulated single-pole bus ducts with a total length of 2,700 meters connect the GIS accommodated in the 85-meter-long switchgear building with the air-insulated part of the substation. The 245 kV breakers were the world’s first of its kind to switch a short-circuit current of 80 kA. The project included engineering, design, supply and delivery, commissioning, all associated control and protection equipment, and buildings for the substation. This projects upgraded the existing 138 kV lines to 230 kilovolts. The GIS helps provide additional load capacity and enhances safety and reliability by redundancy in the system design and earthquake resistance.

Statnett SF energy system operator | Sogndal substation, Norway Sogndal substation is a key node point in Western Norway. It strengthens the Western Norway power grid, increases the electricity transmission capacity, and provides voltage support by installation of a Static Var Compensator (SVC). As a result, it ensures an additional feed-in of electricity and a redundancy capacity provided by wind and small hydro power plants. Siemens Energy was responsible for the planning, delivery, and installation of nine bays for a 420 kV AIS, in double bus, two breaker design, three bays for a 145 kV AIS, in single bus, single breaker design. Furthermore the contract was comprising the connection of the existing 300 kV transmission lines with the new 420 kV substation and the design, delivery, and installation of a +/- 250 MVAr Static Var Compensator (SVC).

Siemens Energy high-voltage substations incorporate the strong performance of one of the world’s leading engineering companies and supplier of power transmission products, solutions, and services. If you want to learn more about the advantages of Siemens Energy's time-tested, proven solutions and to delve into all technical details, simply contact the Siemens Energy Customer Support Center and have your individual questions answered directly by our experts.

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Air-Insulated Substations (AIS): Traditional substations where electrical equipment, such as switchgear and transformers, are installed in open air. These are cost-effective for areas with sufficient space.

Gas-Insulated Substations (GIS): Compact substations where electrical components are enclosed in a gas-insulated, sealed environment. GIS solutions are ideal for urban areas or locations with limited space due to their smaller footprint and enhanced safety.

Hybrid Substations: A combination of AIS and GIS technologies, offering flexibility, space optimization, and cost efficiency. These are often used when a mix of compactness and traditional open-air setup is required.

Mobile Substations: Portable substations designed for temporary or emergency use. They are pre-assembled and can be quickly deployed to restore power after outages or for temporary grid expansion.

Digital Substations: Substations equipped with advanced monitoring, control, and automation systems. They use digital communication protocols to improve efficiency, reliability, and real-time data analysis.

Offshore Substations: High-voltage substations designed for offshore wind farms. These substations collect and step up electricity generated by wind turbines before transmitting it to onshore grids.

Siemens Energy customizes its high-voltage substations to meet specific customer requirements, incorporating state-of-the-art technology to ensure efficiency, reliability, and environmental sustainability.

Gas-insulated switchgear (GIS) substations offer numerous benefits:

Space Efficiency: Require up to 90% less space compared to air-insulated switchgear (AIS), making them ideal for areas with limited land availability.

High Reliability: Enclosed design protects equipment from environmental factors like dust, humidity, and pollution, ensuring consistent performance.

Enhanced Safety: Reduced risk of electrical arcs, short circuits, and fires due to the gas-insulated, sealed design.

Low Maintenance: Minimal maintenance required, reducing operating costs and downtime.

Suitability for Harsh Environments: Perform well in extreme conditions, including coastal, industrial, and seismic-prone regions.

Long Lifespan: Designed for reliable operation over 30–40 years or more.

Fast Installation: Pre-assembled and tested units reduce on-site installation time.

Scalability and Flexibility: Modular design allows for easy upgrades and expansion.

Siemens Energy provides turnkey solutions for the construction and operation of substations, including:

Design and Engineering: Customized substation designs tailored to specific project requirements.

State-of-the-Art Technology: Advanced air-insulated (AIS), gas-insulated (GIS), hybrid, and digital substation solutions.

Project Management: Comprehensive project management for smooth execution from planning to commissioning.

Installation and Commissioning: On-site support to ensure timely and efficient installation.

Operation and Maintenance Services: Long-term maintenance contracts, training, and remote monitoring solutions to maximize reliability and performance.

Digital Solutions: Integration of cutting-edge digital tools for monitoring, automation, and real-time data analysis.

Siemens Energy offers a range of solutions to upgrade or expand existing substations:

Modernization of Equipment: Replacement of outdated components with advanced and energy-efficient systems.

Capacity Expansion: Modular solutions to increase substation capacity to meet growing energy demands.

Digital Upgrades: Integration of digital monitoring and control systems to improve operational efficiency.

Retrofit Solutions: Upgrading existing AIS or GIS systems without the need for complete replacement.

Scalable Designs: Flexible designs that allow seamless integration of new equipment into existing infrastructure.

Yes, Siemens Energy specializes in providing substation solutions for remote or challenging environments:

Compact Gas-Insulated Substations (GIS): Ideal for space-constrained or harsh environments, such as deserts, mountains, or offshore platforms.

Robust Design: Equipment designed to withstand extreme conditions, including high humidity, salty air, heavy pollution, and seismic activity.

Mobile Substations: Portable and pre-assembled units for temporary or remote applications.

Offshore Substations: Custom-built platforms for offshore wind farms and oil or gas installations.

Tailored Solutions: Each project is evaluated to provide a substation design that meets the specific requirements of the environment and application.