March 2017

Please see our Dissemination webpages for details of researcher publications.

WP1: Connection of offshore wind power to DC grids

This Work Package is led by UPC and has researchers, Marc Cheah, Muhammad Raza, Kevin Schönleber and Domenico Ricchiuto, based in Cardiff, UPC and ALSTOM (GE).

This WP has achieved all expected objectives through completion of all planned tasks, milestones and deliverables. 

O1: Design and analyse the topologies of offshore DC grids. Some work has been done in the direction of designing, analysing and controlling offshore AC hubs comprising several wind farms and power converters. Next steps will include multiterminal HVDC systems and offshore HVDC grids.

O2: Determine steady state operation characteristics. The power converter operation characteristics have been identified and algorithms for analysis have been developed.

O3: Develop dynamic control systems for offshore DC grids. Appropriate models have been developed to analyse the dynamic behaviours of offshore AC hubs with offshore wind power plants.

WP1 milestones

• DC grids suitable for offshore wind determined
• Converter characteristics determined
• Algorithms for determining operating points developed
• Wind farm model available for use
• Wind power reduction method developed

WP1 Deliverables

• Various DC grid configuration; cost model technical index and comparison algorithm
• Various operation modes of converters, V-I characteristics
• Methods for determining the operating points
• Controllers of wind farm converters of the DC grid
• Methods to reduce wind power output to avoid over DC voltage

WP2: Investigation of voltage source converters for DC grids

Cardiff led this work package and WP members are Cinergia, KU Leuven and CEPRI, represented by researchers Agustí Egea, Robert Renner, Jorge Gonçalves and Abel Ferreira.

The main research objectives of WP2 have been to investigate the interaction of various voltage source converters (two level, half bridge MMC (modular multi-level converter), full bride MMC and mixed MCC) operating in the same DC grids.

All WP objectives have been met and all planned tasks, milestones and deliverables have been achieved.

O4: Design and compare various voltage source converters

O5: Investigate power flow control in DC grid

O6: Develop tools for analysing and simulating converter stations

WP2 milestones

• Model of voltage source converter developed
• Identification of the problem in various configurations and solutions provided
• Recommendation on the DC grid standardisation
• DC grid configuration tested
• Simulation software packages and experimental test platform available for use

WP2 deliverables

• Models of two-level and multi-level converters for simulation
• Cost model technical index and comparison algorithm
• Configurations of converter stations; configurations of DC grid with combination of different types of converters
• Suggestions on the DC voltage levels
• Recommendation on the standard for connecting more converters
• Simulation models of converters, cables, grounding and DC network

WP3: Relaying Protection

Universidade do Porto ledthis work package and WP members are EFACEC, UPC and KU Leuven.

Researchers have been: Mohammed Meraj Alam (UPORTO), Ataollah Mokhberdoran (EFACEC), Rodrigo Teixeira-Pinto (UPC) and Sahar Pirooz-Azad (KU Leuven).

All of this WP’s objectives have been achieved via the completion of all of its forecast tasks, milestones and deliverables.

O7: Analyse DC grid faults

O8: Develop DC protection algorithms and post-fault restoration schemes

O9: Investigate AC protection with DC grids

WP3 milestones

• DC protection requirement determined
• DC circuit breaker technologies summarised
• DC protection algorithm developed –
• Post-fault restoration with various DC circuit breakers and isolators determined
• Solution of AC protection upgrade provided

WP3 deliverables

• Determined specification of DC circuit breakers to meet DC fault handling requirements
• Test circuit for DC protection available
• Protection algorithm suitable for DC grids
• Procedures to clear the DC faults and restore the DC grid
• Impact of DC grid to AC protection –
• Solution to reduce the impact of AC protection

WP4: Interactive AC/DC grids

WP4 was led by KU Leuven and had members based at Cardiff, ELIA, DTU and Cardiff: Tibin Joseph, Gen Li, Alejandro Bayo Salas, Jayachandra Naidu and Qing Mu. ESR9 Robert Renner of WP2 also contributed to the work package.

The objectives for the WP have all been met, alongside the completion of all planned tasks, milestones and deliverables.

O10: Develop simulation and experimental platforms for the integrated DC/AC system.

O11: Investigate impact between AC and DC grids

O12: Validate integrated DC/AC systems using simulation and experimental platforms

 WP4 milestones

• Impact between AC and DC grids determined
• Recommendation of DC grid code made
• suggestion on AC grid code made
• Control strategy to remove the obstacle for DC/AC interconnection designed
• AC/DC system and control strategy validated
• Simulation platforms available for use
• Test rig available for investigating DC/AC grids

WP4 deliverables

• Integrated AC/DC grid model developed on various simulation tools
• Power flow algorithm developed; determination of the impact of AC faults on DC grids
• Determination of the impact of DC faults on AC grids
• Recommendation of DC grid code to be met by any new terminal
• Suggestion of the AC grid code to connect DC grids
• Controllers to improve stability of AC grid and to damp the SSR developed
• Validated AC/DC grid models; validated control system
• Experimental test platform available for use
• Coordinated control strategies of multi-terminal DC grids for ancillary services delivered by wind power plants

WP5: Network training events

ESRs and some researchers from outside the network, attended the final network training week in Cardiff, UK in July 2016.  See the event webpage for details.

MEDOW has met, and exceeded, all of  its network training deliverables. MEDOW researchers have benefitted from a wide range of training activities, including industry days, personal skills development, lectures from our Visiting Scientists, and group discussions of their individual projects. MEDOW-hosted events contributed 455 person days of training to researchers from outside the network.

WP6: Training of individual ESR/ER

The project has met its objectives and deliverables in this area, with all ESRs and ERs completing and updating Personal Career Development Plans, all ESRs enrolled on PhD programmes (with two doctoral degrees already awarded and two submitted theses awaiting defence) and all secondments completed.

WP7: Dissemination and outreach activities

MEDOW researchers have excelled in this area with over 200 dissemination, communication and outreach activities taking place, including 28 journal articles, 66 international conference papers and a patent application. Public outreach took place in the form of informal talks, visits to schools, a Facebook page and stories in the non-specialist press. Details of MEDOW’s publications, presentations and public outreach activities can be seen on the Dissemination webpages.

WP8: Network management

The network submitted all necessary reports to the European Commission to deadline. A Mid-Term Review meeting with the Commission and an external technical evaluator in January 2015 was highly successful.  A project website has been available and regularly updated since summer 2013. All network meetings took place and all researchers were recruited as as planned. The project has been steered by its Grant Agreement with the European Commission, an internal Consortium Agreement and a Supervisory Board, which has met at least twice per year.