Optimal line flows based on voltage profile, power loss, cost and conductor temperature using coordinated controlled UPFC

In the context of flexible operation and bidirectional line flows in modern transmission systems, suitable line flows are essential for safe, secure and stable power systems. Improper line flows may deteriorate stability and longevity of transmission lines. To avoid line outage and faults, improvement in thermal margin of conductors by regulating line flows is a practical consideration. To maintain and control the line flows, the unified power flow controller (UPFC) is the most appropriate compensating device. Thus, in this study, line flows are considered as state variables to optimise several functions, like, voltage deviation index, active and reactive power losses, temperature of conductors and cost of UPFC. The UPFC is modelled with practical losses like switching, coupling and internal transmission losses. Suitable line flows are obtained for the 30-bus and 57-bus test systems by applying an adaptive-version of the wind-driven optimisation (AWDO) algorithm. The AWDO is designed using two innovative tuning parameters: a decaying friction coefficient to reduce the probability of stagnation, and an adaptive velocity function to maintain diversity. The results are compared among different cases of line flows, validating the necessity of the technical challenge. The performance of AWDO is compared with other techniques, suggesting its superiority over other methods.