Direct current microgrids to be tested in Europe’s power system


The potential of direct current (DC) microgrids to advance Europe’s green energy ambitions will be demonstrated in the new project TIGON.

The Horizon 2020 supported project Tigon is focussed on deploying DC-based grid architectures that can improve the reliability and resilience of a decentralized and renewables-based system.

TIGON will develop a set of flexible and replicable hardware and software solutions to optimize the control, operation and protection of DC grids while providing ancillary services to the main network, Jesús Muñoz, TIGON coordinator and power electronics engineer at Spanish research centre Fundación CIRCE, told Smart Energy International.

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Most grid infrastructure is based on alternating current. Conversely, most renewables generate a DC output, and also most modern electrical equipment such as laptops, mobile phones and LED lighting operate on DC. TIGON aims to make the case for hybrid microgrids to bridge the legacy AC grids and the growing DC infrastructure.

Muñoz says that a modular concept of a DC-based hybrid grid is proposed, in which the main connection of the MV DC to the grid is performed by a solid state transformer and different assets and LV grids depart from the microgrid at several points in an interconnected manner.

“This concept has been designed to assure the operation of DC grids in different modes, such as connected to the main grid or islanded, as well as to accommodate high shares of renewable energy,” Muñoz says. “This will enable smooth integration of DC grids within the existing electricity grid based mainly on AC.”

The novelty of this approach relies on the integration of the physical and software developments, he adds.

The project involves 15 partners from eight countries – Belgium, Bulgaria, Finland, France, Greece, Italy, Portugal and Spain.

The technology will be demonstrated at two sites. One is at Soria in northern Spain under the state research organization CIEMAT. The second is at the French Alternative Energies and Atomic Energy Commission’s National Solar Energy Institute at Le Bourget-du-Lac in southeast France.

At both sites, a hybrid grid will be built with MV and LV DC, and LV AC sections will be demonstrated integrating loads, renewable energies and energy storage systems.

Two further sites have been selected for replication and commercialization of the technologies, one in a residential sector in Naantali, Finland and the other on the metro DC grid in Sofia, Bulgaria.

Alongside these activities, the project also proposes to set up wide area monitoring, protection and control (WAMPAC) systems for stability and security purposes.