# Relationship between Fault Level and System Strength in Future Renewable-Rich Power Grids  
[PERSON]  
1 Electrical Engineering Department, Princess Sumaya University for Technology, Amman 11942, Jordan 1, [PERSON]  
2 School of Technology and Innovations, University of Vaasa, FI-65200 Vaasa, Finland 2, [PERSON]  
3 Team Leader Power Systems Studies, Power Systems Consultants Australia Pty Ltd. (PSC), 3 Spring Street, Sydney, NSW 2000, Australia 3, [PERSON]  
4 Department of Electrical Engineering, The University of Jordan, Amman 11942, Jordan 4, [PERSON]  
5 Energy Engineering Department, German Jordanian University, Amman 1180, Jordan 5,  
[PERSON]  
1 Electrical Engineering Department, Princess Sumaya University for Technology, Amman 11942, Jordan 1,  
[PERSON]  
6 Electrical Power and Mechatronics Engineering Department, Tafila Technical University, Tafila 66110, Jordan 6  
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adopted as a helpful tool to measure the system strength (i.e., the system impedance) locally around the power grid [6; 7]. For instance, a higher fault level point indicates a lower system impedance and a closer point to the generation centre. Although system impedance, also referred to as Thevenin impedance, when measured at steady-state conditions at a certain node may differ from that concerning dynamic fault conditions, these two values might be almost the same in classical power systems, specifically at load buses [8]. This is supported by the assumption that the sub-transient and transient effects of synchronous machines can be neglected. Therefore, estimating the system impedance, to an extent, is employed to calculate the fault level and vice versa. Thus, the efficacy of the fault level scanning tool has been proven in classical power systems dominated by SGs, as the fault level, to an extent, would represent the system impedance. With the increased penetration of PE-based RESs, such tools may be invalidated in future grids. This might be attributed to the controlled fault current response from those non-synchronized RESs opposing the situation of classical SGs that are directly coupled with the grid. RESs not only have limited fault contribution, but they also have different fault signatures and characteristics, mainly due to the their converter's controllers and protection setup during the faults [9]. Moreover, these RESs cannot be modelled as voltage behind an impedance, which is the case with SGs. Hence, the increased penetration of RESs when accompanied by decommissioning of large SGs may lead to the grids being operated under lower fault level conditions. Regardless of the low fault level contribution, depending on the technology, the controllers, and the fault-ride through requirements set by grid codes, RESs may still contribute partially to the system strength in normal operation conditions.