With the growth of cities, new substations are increasingly being built in urban areas, which means size, silence and aesthetic appearance are key considerations.
ABB’s innovative technologies can shrink the size of an electrical substation by up to 70 percent. Accommodating equipment below ground frees valuable space for other uses.
Lauttasaari substation
A typical example of what ABB can achieve is a substation constructed near Helsinki’s city centre for Helen Electricity Network, the local electricity distribution company for the region.
Lauttasaari is the first residential area in the city to have a 110/10.5 kV substation equipped with low-loss, quiet and energy-efficient components. The indoor substation consists of two 110/10kV 31.5 MVA power transformers, featuring an innovative inverter-based cooling system, and feeding 10 kV UniGear double busbar switchgear. It serves the residential and commercial area of Lauttasaari and also Länsimetro, the world’s most northern metro system.
Lauttasaari’s substation is located only eight metres from the nearest residential balcony and has a small footprint. In urban surrounds, the noise issue is also very important. The noise coming from the substation has been reduced by installing the transformers in a closed space and putting the cooling system between the transformer bunkers. To minimise the noise caused by fast-spinning fans, an AC inverter has been deployed to regulate the speed of the fan blades, and substantially decreased energy losses in the cooling system. The inverter-based cooling system also keeps the transformer as evenly heated as possible. This slows down the aging of the transformer insulation, ensuring a longer life-cycle.
The next level – going underground
The next step in urban substations is ABB’s underground substation concept that enables up to 98 percent of the installation’s volume to be hidden. Only the cooling ducts and the access routes need to be above ground. This enables substations to be environmentally friendly, almost unnoticeable, and have none of the planning problems encountered by surface- built solutions.
Underground substations are not a new idea and many partially underground installations are already in operation. They must contain essential equipment such as transformers, gas-insulated, high-voltage switchgear, medium-voltage switchgear, automation, protection and control systems, auxiliary equipment for station services, AC and DC distribution boards, batteries, ventilation and air-conditioning systems, as well as fire protection systems.
Where they differ is that particular attention must be paid to temperature profiles, sizing of cooling and ventilation systems and permissible noise emission levels from ventilation fans.
These innovative and proven solutions enable the most stringent requirements for power supply within urban areas to be fully met – compactness, economy, reliability and safety,
all while allowing for easy maintenance access and future expansion.
