A Busbar Protection of DC Distribution Network Based on Current Mutation

With the rise of DERs penetration rate and the substantial increase of urban DC loads, the status of a flexible MVDC distribution system is increasingly important in cities. Taking into account the DC bus faults of overhead lines, this paper takes a four-terminal flexible MVDC distribution system with multi-section lines as the research object. A bus protection scheme based on the current mutation is proposed to ensure the fast removal of bus faults after faults. In this paper, from the perspective of current mutation, the current amplitude and polarity will change differently after bus fault under the different fault location and fault type. An improved calculation method of current mutation is proposed. Mutation amplitude can quickly detect the bus fault, while mutation polarity is used to determine the location of the fault bus. Finally, a four-terminal DC distribution system with multi-section overhead lines based on PSCAD, using simulation tests to illustrate the reliability of the proposed scheme.