Hybrid AC/DC Transmission Grids

Dear Colleagues,

OVERVIEW

The origin of the commercial use of electricity was marked by a series of events regarding competition between alternating current (AC) and direct current (DC), the famous “war of the currents”. AC has dictated the paradigm used in the development of the commercial power systems for many years. Today, AC is a mature and well-developed technology, but AC transmission has limitations—it is not perfect! Recent technological developments and a cost reduction in power converter technology have made the use of DC a viable option to tackle the major upgrades needed to ensure reliability and an economic power supply for sustainable low-carbon societies.

DC systems have evolved from the old fashion, dedicated to a very specific and out-of-the-way application, to become more integrated into AC systems, offering many technical and economic advantages.

Today, modern hybrid AC/DC grids combine the advantages of AC and DC systems—providing an increased operational flexible control that improves the reliability of the whole power supply. The higher cost reduction and technological breakthrough in power electronic converters have motivated an increasing use of DC, ranging from low voltage (LV) to ultra-high-voltage direct-current (UHVDC; e.g., up to 10 GW for 800 kV) networks. DC systems are used in many applications, namely: for typical HVDC uses, like water crossings, asynchronous interconnections (back-to-back); and long-distance power transfers, including access to remote renewables (point-to-point), transmission in areas with severely restricted right-of-ways, and HVDC-networked (multi-terminal) grids. Also, DC systems have been used in many other applications, such as micro-grids, LV and MV distribution systems, DC distribution systems in ship propulsion, and DC in buildings and data centres, to name a few.

The modern hybrid AC/DC power grids allow for the increased penetration of low-carbon technologies, and some of the renewable technologies are inherently compatible with DC systems like solar and wind, but also the energy storage applications (batteries). Also, DC has been part of the consumer-side for years; the DC internal structure is a reality in many devices and many appliances, ranging from data centres (MW scale) up to lightning (W scale).

OBJECTIVE

This Special Issue is dedicated to identify, address, and disseminate state-of-the-art research works on in novel aspects of hybrid AC/DC transmission and distribution networks. As a consequence, this Special Issue brings together scholars, researchers, scientists, engineers, and administrators on a common platform, to disseminate the scientific innovations that benefit the scientific community and have a positive impact on society.

TOPICS OF INTEREST

Topics of interests for this Special Issue on “Hybrid AC/DC Transmission Grids” include, but are not limited to, the follow:

• Innovative modelling techniques (EMT and RMS) for integrated simulations of large hybrid AC/DC grids;
• Modelling and simulation of the electromechanical and electromagnetic phenomenon in hybrid AC/DC grids;
• Co-simulation and hardware-in-the-loop simulations as a tool for the validation, testing, and verification of hybrid AC/DC grids;
• Advances in power apparatuses enabling development and enhanced features in hybrid AC/DC grids (e.g., DC transformer, DC circuit breakers, novel technologies of generation, and energy storage smart converters);
• Innovative methods for the monitoring and control of dynamic and transient stability of hybrid AC/DC grids;
• Novel methodologies for the planning of hybrid AC/DC grids;
• Optimal economic and secure operation of hybrid AC/DC grids;
• Novel control of TSO/DSO interactions considering hybrid AC/DC grids;
• Challenges and opportunities of a hybrid AC/DC grid in the context of TSO/DSO integration;
• Techniques for the detection and mitigation of different phenomenon related to resonance in power converters dominated by AC/DC grids (e.g., sub-synchronous, super-synchronous, harmonic, and high frequency);
• Novel schemes for the protection of hybrid AC/DC grids, including new features for converter-enabled technologies;
• Role of energy storage and low-carbon technologies in hybrid AC/DC grids interactions;
• Novel and innovative schemes of early instability phenomenon in hybrid AC/DC grids;
• Islanding and synchronisation mechanisms of hybrid AC/DC grids;
• New techniques of blackout restoration in the context of hybrid AC/DC grids;
• Challenges in the standardisation, policies, regulation, and market design of hybrid AC/DC grids;
• Recent important projects and experiences on AC/DC grid projects, with special interest in multi-terminal DC projects and renewable power and AC/DC connections;
• High voltage DC/DC converter topologies and control;
• MVDC distribution grids and collector grids for large solar plants.

The guest editorial team are soliciting high quality, original, and of timely significance research papers with novel contributions in all of the above aspects.

Prof. Dr. Francisco Gonzalez-Longatt
Prof. Dr. Jose Luis Rueda
Guest Editors

Manuscript Submission Information

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