Adaption of Inverter-Based System Controls to Reduce the Negative Impact of Intermediate Infeed on Distance Protection Systems

Inhalt:
In this paper, two algorithms will be developed to reduce the negative impact of inverter-based intermediate infeed on the functionality of distance protection systems. The first algorithm is used to classify fault locations by characteristic points of measured impedance trajectories at the inverter-based system grid node. The second algorithm defines inverter current set points which are applied during faults, so that the error impedance measured by a protection device is plain resistive. The proposed algorithms will be derived with a simplified model of a medium voltage grid, and validated with both the simplified model, and a detailed excerpt from a Cigré benchmark system. The validation shows feasibility of the proposal, while focusing on single-line-to-ground faults. In conclusion, the algorithms will be further developed in order to cover different kinds of faults, and an experimental validation will be performed with a laboratory-scale grid and an actual inverter-based system.