Contingency constrained TCSC and DG coordination in an integrated transmission and distribution network: A multi-objective approach

•Developed a composite severity index for transmission line outage contingency, accounting for both power flows and bus voltages.•Developed a contingency constrained approach for coordination of TCSC and DG thereby improving ATC, reducing power losses and voltage deviation.•Establishes a correlation between ATC Versus Power loss and ATC Versus Voltage deviation, under both normal and contingency conditions. Transmission System Operators (TSO) deploy Flexible AC Transmission Systems (FACTS) for congestion management in order to meet technical and multilateral power supply transactions. These power commitments are however constrained by thermal, voltage and stability limitations. On the other hand, the campaign to de-carbonize the power supply framework as seen Distribution System Operators (DSO) accommodate an increased penetration of Distributed Generation (DG) within their distribution networks. However, prerogative of system operators for separate planning of FACTS and DG systems can worsen power system’s key performance indicators especially under huge load growth and severe contingencies. Therefore, this paper developed an approach for contingency constrained coordination of Thyristor Controlled Series Compensator (TCSC) and DG through a multi-level optimization, comprising of a hybrid real power flow index and particle swarm in the first level and a multi-objective variant of particle swarm optimization in the second level. The contingency constrained coordination aimed to improve Available Transfer Capability (ATC), power loss and voltage deviation. Two models of DG were coordinated with TCSC under normal and contingency cases. Results indicate that while ATC improvement for various transactions were achieved with TCSC, additional power losses incurred was further reduced with DG deployment in coordination with TCSC. Furthermore, the Pareto front, which establishes the correlation between objectives shows a diving parabola that is partly nonlinear. Also, the TCSC−DGPQ provide superior ATC and power losses compared with TCSC−DGPV. Again, under (N−1) contingencies, the TCSC−DGPQ provides improved ATC compared with other contingency cases under TCSC only.