Determination of sectionalising strategies for parallel power system restoration: A spectral clustering-based methodology

•This paper proposes a methodology for determining sectionalising strategies for the purpose of parallel system restoration.•The new methodology creates islands that satisfy the critical constraints for parallel system restoration.•The electrical distance is used to create islands that have strong internal connections but weak external connections.•The paper designs electrically cohesive islands with minimum number of tie-lines and maximum number of internal connections.•The approach is validated using two Institute of Electrical and Electronic Engineers (IEEE) test networks, and simulation results are found in less than 1 s.

Parallel power system restoration (PPSR) accelerates the restoration of a system in complete blackout by restoring isolated sections (islands) of the network in parallel. These islands are defined during the preparation stage of PPSR using a sectionalising strategy that considers system information collected after the blackout and must satisfy multiple PPSR constraints. This paper introduces a methodology based on spectral clustering that, in contrast to existing approaches, uses the physical and inherent properties of the network to determine a suitable solution. An undirected edge-weighted graph is initially constructed based on the electrical distance between buses, and constraints related to transmission line availability and cranking groups are included by modifying the edge-weights of the graph and using a subspace projection. This graph is then used to define islands that have strong internal connections but weak external connections, whilst satisfying the following constraints: blackstart availability, load-generation balance, voltage stability and the ability to monitor synchronisation between adjacent islands. Simulation results for the Institute of Electrical and Electronic Engineers (IEEE) 39- and IEEE 118-bus test systems demonstrate the ability of the methodology to define a strategy that creates strongly connected islands. Additionally, they indicate that the new approach determines solutions that have larger ratios between the inter-cluster electrical distance and the intra-cluster electrical distance for larger systems.