Investigation of the Short-Circuit Power Significance in Converterbased Power Systems

The classical power system has been operated with synchronous generators (SGs). The unique physical properties of SGs have been used to define the characteristics of classical power systems. One such parameter is short-circuit power (SCP), which is based on the short-circuit current characteristics of SG and is an important parameter for the planning and operation of power systems. However, with the integration of more renewable sources of energy (RES), the generating units are power electronics-based, that have different short-circuit characteristics due to its different physical properties. Due to the different short-circuit current characteristics, the definition and meaning of SCP need to be re-evaluated. This paper addresses this question by investigating the classical definition of SCP using the converter-based IEEE-9 bus system. First, the short-circuit currents for future converter-based system with SG, grid following converter (GFL), and grid forming converter (GFM) converters, are investigated. Then taking the dynamic simulation as reference, the validity of static calculation method based on VDE 0102 is investigated and discussed. After that, the definition of SCP based on different time-frame of short-circuit currents (initial short-circuit current and breaking fault current) is related to the system response after short-circuit and its significance to different operational requirements is presented.