Zero-sequence blocking transformers for use in MV distribution systems - comparison of single core VS multi-core designs

Journal article, 2023

The purpose of this paper is to highlight possible applications of ZSBTs in medium voltage electric distribution networks, describe design challenges and to compare two main types of ZSBT designs. Dimensioning criteria have been analyzed based on network characteristics of resonance earthed 22 kV distribution networks with low short circuit power. A comparison has been made between a single core ZSBT design and a multi-core ZSBT design. The designs have been analyzed using finite element method in time domain and 3D. Results show that both designs fulfill the design criteria. The single core design demonstrates a lower leakage reactance and lower material usage for use in 22 kV networks. The multi-core design is overall a more simple design and can be designed with general design principles for single-core transformers.