Title: Protection requirements for a multi-terminal meshed DC grid
Authors: Van Hertem, Dirk
Ghandhari, Mehrdad
Curis, Jean Baptiste
Despouys, Olivier
Andrée, Marzin #
Issue Date: 13-Sep-2011
Publisher: Cigré
Host Document: Cigrè International Symposium THE ELECTRIC POWER SYSTEM OF THE FUTURE Integrating supergrids and microgrids
Conference: Cigrè International Symposium THE ELECTRIC POWER SYSTEM OF THE FUTURE Integrating supergrids and microgrids location:Bologna date:13-16 September 2011
Abstract: Multi-terminal high voltage direct current (HVDC) or meshed DC grid is considered to be the preferable
option for the much anticipated future supergrid for Europe. This supergrid should connect distant generators
to increase the introduction of renewable energy sources and to provide an increased security to the pan-
European power system. Although many technical limitations remain, the protection system is often regarded
as the most critical one. The protection system for a meshed DC system has particular difficulties compared
to the traditional AC system because of the DC current that has no zero crossings and the line impedance that
does not limit the fault current. As a consequence, the DC currents will rise much faster and interrupting the
fault current is significantly more difficult in the meshed DC than it is in an AC meshed system. Furthermore,
traditional protection devices such as impedance relays cannot be used. New alternatives must be found, such
as considering a joint strategy between the protection devices and the VSC converter controls.
In order to provide a reliable supply of electric energy, the protection system of a meshed DC system
should have a number of minimum requirements: fast fault detection, selectivity in opening the correct
breakers, and redundancy.
This paper discusses the different requirements for the protection of a multi-terminal meshed HVDC
system. It will provide a list of boundary conditions for such a protection system, as well as an overview of
the current state of the technology and the remaining gaps. Some pointers to potential technologies that may
be used in the future grid protection are given. The paper will not focus on hardware developments, but will
rather indicate the requirements that these devices (or joint set of devices) must fulfill.
Publication status: published
KU Leuven publication type: IC
Appears in Collections:ESAT - ELECTA, Electrical Energy Computer Architectures
# (joint) last author

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