Reasons behind this project

The increasing penetration of IBRs at various locations in the system, including distribution, the more frequent topology changes in the network, and the decommissioning of conventional power plants, the short-circuit levels in the network exhibit more variations. An accurate assessment of its maximum and minimum value at substation level, together with peak and steady-state short-circuit current calculation for balanced and unbalanced faults is more than ever necessary for personnel safety, equipment damage and security of supply.

Besides, in situations when the IBRs are not connected to the grid, short circuit levels are decreasing. The SCR (short-circuit ratio) is no longer relevant to detect potential unstable situations in presence of power electronics.

This single steady-state short-circuit value (Icc ) at each electrical node of the grid is used for several system operator applications: structure dimensioning study, protection system analysis, power quality assessment, stability criteria (SCR) in design, planning and operation of electrical power systems. An over-estimation of the short-circuit maximum value can lead to overinvestment, whereas an under-estimation poses a safety risk for personnel on site and can lead to failure and loss of an entire substation. Wrong assessment of the minimum value will increase stability risks, or can lead to malfunction of protection devices.

Objectives

uSCC aims at inventing a new quasi-static short-circuit current simulator, embedding adequate modelling of IBRs, FACTS, HVDC and load. This new simulator would still be based on solving the resulting algebraic system of equations (Kirchhoff), while accounting for devices limits, a logic to embed IBRs controls, while ensuring an acceptable computation time. IEC 60909 standard assumptions would be rethought as well along with this simulator, and validation would be made with comparison to EMT simulations. This new approach (simulator, assumptions and validation) could replace the existing one for equipment dimensioning during the planning phase and push the update of the current standard.

Project partners

The project team is currently being defined and the project is open to additional partners.

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