Coordination of Protection and Automation for Future Networks

Technical Brochure 629 was developed by CIGRE Working Group B5.43 and identifies the characteristics of the future grid and the possible evolutions towards it. It also covers the related protection and automation issues. From these issues, potential solutions as well as follow-up investigations are proposed. Based on these points, requirements related to protection and automation of Future Networks are evaluated.

The structures of the electric power grids in the 21st century are changing dramatically compared to the grids of the last century. This is driven mainly by the concern with global warming and the replacement of the conventional large coal-fired power plants with distributed relatively small wind or solar generators. However they pose many challenges due to their completely different behavior during normal and abnormal electric power system conditions.
This report looks at the likely model of the future grid and its prospective components and identifies some of the consequences and requirements for changes in the protection, automation and control of the grid.

The first sections of the brochure focus on the drivers for change and the vision for the future grid defined by the changing market and generation structure. Looking at the hierarchy of the future grid, the emergence of the concept of a hybrid Super Grid using both AC and DC transmission is discussed. Regional transmission sub-grids and distribution grids are later described.
The integration of the different types of renewable energy resources at the different levels of the electric power grid hierarchy is analyzed, including their aggregation in Virtual Power Plants.

Considering the challenges that the grids face today, the brochure describes the evolution in electrical networks, such as the changing network and substation characteristics, the system grounding and the physical security.  Six-phase transmission systems, FACTS and solid state transformers and their role in the future networks are presented.
The evolutions of the networks are related also to the interface requirements of distributed energy resources, solar and wind farms and the requirements for dynamic load management of transmission lines.

The impact of the increasing network cable lengths and fault current limitation are also considered together with energy storage systems and non-conventional instrument transformers.
The evolution of the network has an impact on the protection and automation systems. The protection of the evolving distribution systems, HVDC and LVDC networks and six-phase transmission lines is described. The impact of FACTS, power electronics conversion, fault limiters and different types of wind generators on the protection systems is also covered.

After covering the changes in the electric power networks, the brochure concentrates on the developments in protection and automation technology.

The concepts of station bus and process bus as components of the future protection, automation and control architectures are presented.
The evolution in communications technology includes redundancy, wide area communications and communication interfaces with customers. Cloud computing, the Internet of Things (IoT) and cyber security are also discussed.

The use of synchrophasors and the role of IEC 61850 in the protection and automation systems of the future are later described.
They are key components for the implementation of adaptive protection and System Integrity Protection Schemes (SIPS).

Fault location in transmission and distribution networks and requirements for their implementation are also discussed.

The later sections of the brochure include a variety of future networks use cases and solutions from all over the world.
CIGRE Brochure 629 is available for download at:  www.e-cigre.com

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