Spyros I. Gkavanoudis, Dimitrios Tampakis, Kyriaki-Nefeli D. Malamaki, Georgios C. Kryonidis, Eleftherios O. Kontis, Konstantinos O. Oureilidis, José María Maza-Ortega, Charis S. Demoulias: ‘Protection philosophy in low short-circuit capacity distribution grids with high penetration of converter-interfaced distributed renewable energy sources’ in IET Generation, Transmission & Distribution, 0pp, 2020

The ever-growing penetration of converter-interfaced distributed renewable energy sources (CI-DRES) in distribution networks, despite the undoubted advantages, has a profound impact on the traditional protection systems. The protection problem becomes even more complicated as the increase in the CI-DRES penetration level leads to the decommissioning of conventional power plants. Due to the limited current capability of CI-DRES, decommissioning of conventional units will lead to a transmission grid of significantly lower short-circuit level. This study proposes a novel protection philosophy for distribution grids of low short-circuit capacity and high CI-DRES penetration. According to the proposed approach, CI-DRES are controlled to actively participate in the fault-clearing procedure, supporting the short-circuit capacity, in an aggregated form, through the injection of controllable currents. Therefore, conventional overcurrent protection devices can be used, without any additional investments for a protection system upgrade. The CI-DRES fault contribution is based on their relative position to the fault, respecting technical and protection-malfunction constraints. In addition to the short-circuit level, the effect of the feeder parameters and the power factor of the injected fault current on the voltage recovery is also investigated. The proposed protection philosophy is validated via detailed simulations in DIgSILENT PowerFactory.

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