The multiDC Project
The project “MULTI-DC: Innovative Methods and Optimal Operation of Multiple HVDC Connections and Grids” (multiDC) applied in 2016 for funding under the Innovation Fund Denmark framework of “Grand Solutions”. Due to the high number of HVDC connections in the Nordic region, this call pursues new and advanced control solutions to fully employ the benefits HVDC connection has to offer. The specific objective of multiDC project is to develop innovative methods for the optimal coordination of multiple HVDC lines and HVDC grids in systems with high shares of renewables. To achieve this highly ambitious result, multiDC teamed up with established researchers, technology providers, and end customers
The increase of inverter-based generation is phasing out grid-connected generation units, which provide various system services, such as Short Circuit Capacity (SCC), frequency control and rotational energy. Moreover, the clustered renewable generation requires facilitation of huge power influx in a power system, which becomes increasingly challenging for TSOs to control. Due to high controllability and bulk power transmission capability, HVDC technology is a promising replacement to provide such services and help stabilizing the system. To ensure the feasibility of such transition, stability analysis needs to be conducted for low and zero inertia systems, and advanced converter control design should be employed.
In the last decades, HVDC technology has become a common tool in the design of transmission grids. From a technical point of view, the full controllability of power converters gives the opportunity of supporting local AC networks by means of voltage control, frequency support and reactive power compensation. On the economic side, HVDC interconnectors facilitate the exchange of energy and ancillary services between countries. Thus, if HVDC and AC grids are operated in an optimal way, significant cost and energy savings can be achieved. The scope of this project is to benchmark current markets and to propose various path for their evolution in order to unleash the potential of HVDC lines.
HVDC connections will play a key role in an efficient and secure operation of the future system, mainly due to their capability to bulk power transmission over long distances and for fast, flexible control. Today the operation of multi HVDC connections is not coordinated during disturbed system operation. This project’s primary goal is to enable HVDCs active participation in AC system frequency stability by developing advanced control actions. Moreover, these control actions should be carefully coordinated to avoid negative interaction with other stability types and operation factors in all interconnected systems. The aim is to use the current power system infrastructure, without implying large additional investment costs.
Implementation and testing
To analyse the North Sea Wind Power Hub offshore grid stability, and HVDC effective utilization in market operations and emergency control, an environment for testing must be established. This process is separated into two stages: online testing using powerful simulation tools, and hardware-in-the-loop implementation in state-of-art facilities across Denmark. The primary tool for online testing is DigSilent PowerFactory, used to develop Kriegers Flak interconnector, NSWPH, and detailed Nordic Test System models. Once our methods prove viable the implementation is taken to PowerLabDK Real-Time-Digital-Simulator, and, finally, reaches the transmission system operator’s SCADA control room.
MultiDC member, Ph.D. student at Technical University of Denmark (DTU) Andrea Tosatto successfully defended his Ph.D. thesis entitled “Optimization and Market Integration of Multi-Area AC/HVDC Grids”! High-Voltage Direct-Current (HVDC) technology has proven to be an essential tool for the design of transmission grids and for the integration of RES. Thanks to their technical properties, HVDC[…]
MultiDC member, Ph.D. student at Technical University of Denmark (DTU) Georgios Misyris successfully defended his Ph.D. thesis entitled “Towards Zero-Inertia Power Systems: Stability Analysis, Control & Physics-Informed Neural Networks”! Large-scale integration of Renewable Energy Sources (RES), as well as the installation of new High Voltage Direct Current (HVDC) lines, poses new technical challenges concerning the[…]
Enabling better HVDC coordination for frequency stability: multiDC discussion with Nordic Analysis Group!
Two multiDC Ph.D. students, Andrea Tosatto from Technical University of Denmark (DTU) and Danilo Obradovic from KTH Royal Institute of Technology in Stockholm, presented their work to Nordic Analysis Group (NAG) consisting of Nordic Transmission System Operators! The work and discussion revolved around Nordic Power System frequency stability enhancement using High-Voltage Direct Current (HVDC) interconnectors[…]
MultiDC member, PhD student of Royal Institute of Technology in Stockholm (KTH) Danilo Obradovic successfully defended his Licentiate thesis! Danilo has shown big potential in improving frequency stability using an enhanced HVDC control. By synchronizing the control actions of several HVDC links, their droop based supplementary action relieves the work that primary frequency control (FCR-D)[…]
The eight multiDC workshop adapted to “new normal” and again held online! The focus of the meeting was the NSWPH and its influence on the power flows and frequency in the Nordic power system. The feedback from industry and various TSOs were positive and new analysis directions are identified! Apart from that, the discussion started[…]
We are proud to announce that multiDC work was mentioned in Ingeniøren journal! 1. “Optimizing the market-clearing algorithm can save the Nordic electricity grid millions every year“ The proposal by multiDC is to include piece-wise HVDC loss factor and AC lines loss factors. The outcome would decrease the flows between zones with zero price difference[…]
Great news – three multiDC papers got accepted in highly regarded Cigre Session 2020 conference on new and emerging technologies in electrical power systems! 1. “The North Sea Wind Power Hub: System Configurations, Grid Implementation, and Techno-economic Assessment” prepared by Misyris, T. Van Cutsem, J. . Moller, M. Dijokas, O. Renom Estragues, B. Bastin, S.[…]
These challenging times due to the COVID-19 virus forced everyone to adapt, but we are happy to announce that the seventh multiDC workshop was organized – this time online! The workshop was organized into two sessions: a technical committee and a steering committee. During the technical committee, work packages 2-5 were addressed, where the EMT[…]
Find below the demonstration material! Slides and videos: Jacob Østergaard (DTU) – Welcome to the Center for Electric Power and Energy – VideoFitim Kryezi (Energinet) – Presentation of the North Sea Wind Power Hub and the role of interconnections – Video – SlidesLena Kitzing (DTU) – Political visions meeting market and regulatory challenges for North Sea offshore hubs –[…]
On 6. – 7. in March, multiDC had its fifth workshop towards “Controlling the power flows”. This time the event was hosted by Energinet in Fredericia, Denmark – headquarters of Energinet! During the main session, the discussion was focused on the North Sea Wind Power Hub operation in zero-inertia, the political context of the project,[…]