Hitachi Energy: Hitachi Energy power quality solution reduces grid connections by almost half in European rail corridor

Lithuanian Railways (LTG), the national rail operator, is electrifying its most important rail corridor, which runs from one end of the country to the other: between Vilnius, the capital, and Klaipeda, the principal port – a distance of 377 kilometers.

When completed in 2024 the corridor will carry three quarters of Lithuania’s rail freight and two-thirds of its rail passenger journeys.

Electrification of the corridor will replace polluting diesel-powered locomotives with lower-carbon high-speed electric trains. This will reduce CO2 emissions by 150,000 tons a year and cut operating costs by 40 percent, according to the Lithuanian government.1

Rail electrification requires grid connections to link the corridor to the power grid. There are two ways to do this: with conventional transformer substations, which have several disadvantages, or by using Hitachi Energy static frequency converter (SFC) stations.

The Hitachi Energy solution will, among many other operational benefits, reduce by almost half the number of grid connections needed to power the rail corridor.

Solution

Hitachi Energy was selected by ELECNOR, the Spanish infrastructure, energy and telecommunications company, and its consortium partner Inabensa, which are responsible for the electrification of the entire project.

The solution comprises eight SFCs which are installed at grid connections along the rail corridor. The SFCs are pre-assembled, pre-tested and commissioned at the Hitachi Energy factory in Turgi, Switzerland for speedy installation and energization.

In rail applications, SFCs are traditionally used to convert electricity from the three-phase power distribution grid, which operates at a frequency of 50 or 60 Hertz (Hz), to the single-phase rail power network, which in some countries operates at 16.7 or 25 Hz.

In Lithuania, both the power grid and the rail network operate at the same 50 Hz frequency, so conversion is not needed. However, the operational and cost benefits of using SFCs far outweigh those of conventional transformer substations.

Unlike conventional substations, SFCs eliminate the voltage unbalance caused by feeding power from a three-phase grid into the rail network. This ensures compliance with the strict grid code regulations of the transmission system operator, thereby reducing risk. It also enables the network to be connected to a medium-voltage distribution grid, rather than a higher cost high-voltage transmission grid.

SFCs dynamically control the voltage and power flow which gives a more stable catenary voltage and increases reliability of the entire traction power system. They eliminate the need for neutral zones between catenary sections fed by different substations. This extends the maximum length of the sections and reduces the number of grid connections.

Impact

As a result, Hitachi Energy’s SFC technology has reduced the number of grid connections needed for the corridor from 14 (for conventional transformer substations) to seven. This equates to a huge reduction in capital expenditure and operating costs for the rail operator, LTG.

The solution will also stabilize the voltage, power grid and rail electrification network, and will potentially enable LTG to increase revenues by providing the grid operator with grid stabilization services.

This is another example of how Hitachi Energy is advancing the world’s energy system to be more sustainable, flexible and secure.