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Inverter-based resources (IBRs) exhibit distinct short-circuit characteristics that challenge traditional protective relays designed for systems dominated by synchronous generators. While research often focuses on IBRs’ positive-sequence currents during faults, their zero- and negative-sequence responses under unsymmetrical faults remain underexplored. Factors such as transformer configurations and grounding methods further complicate the design of protection schemes relying on these sequence components. This paper enhances the understanding of IBR short-circuit behavior during both symmetrical and unsymmetrical faults and investigates the impact of various transformer configurations on these behaviors. We highlight the limitations of traditional protective relays in safeguarding IBRs due to their constrained fault current levels, minimal negative-sequence components, and, in many cases, the absence of zero-sequence currents. To address these challenges, a novel incremental focused directional protection scheme is introduced. This approach offers enhanced fault detection capabilities under the complex conditions posed by high renewable energy penetration and diverse transformer configurations. The proposed method provides a robust solution for ensuring reliable protection in modern power systems with high integration of IBRs, contributing to improved grid stability and resilience.
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Adaptive Distance Protection Based on the Analytical Model of Additional Impedance for Inverter-Interfaced Renewable Power Plants During Asymmetrical Faults
Due to limited amplitude and controlled phase of current supplied by inverter-interfaced renewable power plants (IIRPPs), the IIRPP-side distance protection of lines connected to IIRPPs fails to detect the fault location accurately, so it may malfunction. The composite sequence network of a line connected to an IIRPP during asymmetrical faults is analyzed, and an adaptive distance protection based on the analytical model of additional impedance is proposed in this study. Based on open circuit property of negative-sequence network at the IIRPP-side, the equivalent impedance of power grid and current flowing through fault point are calculated in real-time using local measurements, which are substituted into the analytical model of additional impedance to calculate fault location. In the case of negative-sequence reactive current injection from IIRPPs during asymmetrical faults, the error of calculating fault point current from local measurements is analyzed and corrected to ensure reliability of the proposed protection. The proposed protection alleviates the effect of fault resistance in a system with weak sources. In addition, the proposed protection can adapt to different grid codes (GCs), the operation mode change of the power grid, and the capacity change of the IIRPP. PSCAD/EMTDC test results verify the effectiveness of the proposed protection.
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- Award ID(s):
- 2048288
- PAR ID:
- 10315104
- Date Published:
- Journal Name:
- IEEE Transactions on Power Delivery
- ISSN:
- 0885-8977
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1109/TPWRD.2021.3138128
