Scottish Power to build medium-voltage transmission link in Wales

Scottish Power Energy Networks is deploying Europe’s first medium-voltage transmission direct current link.
Published: Wed 24 May 2017

Scottish Power Energy Network’s (SP Energy Networks) deployment of a medium-voltage direct current link (MVDC) is a critical part of the Network’s Angle-DC project in Anglesey and North Wales.

The Angle-DC transmission project seeks to use an existing AC link between the isle of Anglesey and North Wales, where uncontrolled power flows are forecast to exceed thermal limits of the cables and overhead lines. The link will also provide extra capacity for the integration of renewable generation connecting to the island’s distribution network.

The link aims to demonstrate a novel network reinforcement technique by converting an existing 33kV AC circuit to DC operation.

Medium-voltage transmission to improve power flow

As the electricity demands in the region increase, uncontrolled power flows are putting the system at risk by exceeding thermal limits of the cables and overhead lines.

The MVDC link, which will be delivered by GE Energy Connections, is aimed at improving electricity flow and control in voltage. Besides, conversion of AC assets to DC operation will improve the thermal capability of the circuit. The MVDC link will address the issues caused by uncontrolled power flows which are as a result of escalating electricity demands; the uncontrolled flows put the electric system at risk by crossing thermal limits of the overhead lines and cables.

GE’s Power Conversion AC-to-DC converters will be located at a 33kV substation in Bangor and at a similar substation on the Isle of Anglesey. Both the substations will see the 12 units of the MV7000 converters convert 33kVAC to ±27kVDC. This will be done through the existing AC lines connecting the substations.

GE will also be including VISOR 2.0*, an asset management tool that provides remote connectivity to improve service responsiveness, and Data Historian, a data management software that allows data collection, processing and storage, as part of the installation.

This ability to capture and analyse data will enable SP Energy Networks to review the capabilities of the MVDC system and gather insights to develop optimum control algorithms for the distribution system.

According to Sascha Heinecke, industry segment leader, GE’s Power Conversion, the project is a “first of its kind” in the UK and Europe. “The success of this project could impact how grids across the world are future-proofed.”

MVDC a more innovative alternative to renewable integration

According to Kevin Smith, Future Networks Lead Engineer at SP Energy Networks, with the increase in electricity demand and renewable integration, the grid is taking strain.

It is for this reason that additional reinforcement becomes necessary. He added that the addition of the MVDC link on existing assets can be a more innovative alternative to building more substations and connecting underground cables and overhead lines.

Renewable integration is becoming more of a challenge as utilities turn their backs on fossil fuels and concentrate their efforts on renewable generation.

Scottish Power is no exception having invested £168m in renewable energy projects in the first quarter of this year. Scottish Power Renewables is part of Iberdrola, the world’s largest wind energy developer, with an operating portfolio of over 14,000MW. Scottish Power Renewables is responsible for progressing Iberdrola’s onshore wind and marine energy projects in the UK and abroad.

Scotland has been leading the UK in renewable electricity generation through the rapid expansion of wind power in addition to the power generated by hydroelectric plants over the last couple of years.

Renewable electricity generation continues to increase steadily, with onshore and offshore wind, wave and tidal resources being tapped into. Renewable energy development is an integral part of Scotland’s vision of a balanced energy mix to deliver secure, low carbon and cost-effective energy to boost economic development.

The Scottish government has set itself a target for the renewable energy sector to generate 100% of the country’s annual demand for power by 2020.