Troll A 1&2

Troll A 1&2 Overview

The Troll A 1&2 HVDC project is a power transmission system that delivers electricity from the Norwegian mainland to the Troll A offshore gas platform in the North Sea. Commissioned in 2005, it was the world's first power-from-shore transmission using HVDC VSC technology.

Technical Specifications

The Troll A 1&2 system consists of two transmissions, each rated at 44 MW, for a total capacity of 88 MW. It operates at a direct voltage of ±60 kV and uses a symmetrical monopole configuration. The power is transmitted through submarine cables spanning approximately 70 km from the Kollsnes onshore station to the Troll A platform.

Key Components

Onshore Station

At the Kollsnes onshore station, rectifiers connect to the existing 132 kV network through standard power transformers. These rectifiers convert the alternating current (AC) to direct current (DC) for efficient long-distance transmission.

Submarine Cables

The HVDC cables connect the rectifier at Kollsnes to the inverter on the Troll A platform. These cables are designed to withstand the harsh underwater environment of the North Sea.

Offshore Platform Equipment

On the Troll A platform, inverter stations are directly connected to very high voltage (VHV) cable-wound motors without the need for transformers. These motors, supplied by Hitachi Energy (formerly ABB), are rated at 60 kV and 55,000 horsepower, serving as gas pre-compressors.

Control System

The entire system is governed by Hitachi's HVDC Light® MACH control system, which manages the power flow and ensures stable operation of the transmission link and the VHV motors.

Environmental Impact

The Troll A 1&2 HVDC project has significantly reduced the platform's environmental footprint. By eliminating the need for local power generation on the platform, it has avoided annual emissions of approximately 230,000 tons of CO2 and 230 tons of NOx, equivalent to the pollution from 75,000 cars.

Operational Benefits

The implementation of this power-from-shore solution has provided Troll A with a highly reliable power supply, boasting close to 100% availability. It has also reduced the number of offshore workers required and enhanced overall health, safety, and environmental conditions on the platform.

Impact on Gas Production

The installation of the HVDC system and the new compressors has boosted gas pressure on the platform, increasing Troll A's natural gas deliveries to Europe from 85 million cubic meters to 110 million cubic meters per day. This represents nearly 15% of Europe's daily natural gas usage.

Industry Significance

The success of the Troll A 1&2 project has paved the way for further offshore HVDC applications. It demonstrated the viability of power-from-shore solutions for offshore installations and has influenced subsequent projects in the North Sea region.

Expansion: Troll 3&4

Following the success of Troll A 1&2, an expansion project known as Troll A 3&4 was commissioned in 2015. This addition provided two more transmissions, each rated at 50 MW, bringing the total power capacity to 188 MW across all four transmissions.

The Troll A 1&2 HVDC project was a significant milestone in offshore power transmission technology, combining innovative HVDC technology with high-power motors to enable efficient and environmentally friendly operation of one of Europe's most important natural gas production facilities.