Solution of security constrained optimal power flow for large-scale power systems by convex transformation techniques and Taylor series

Security constrained optimal power flow (SCOPF) is a key operation function for today's power systems, extensively used, for example, in the dispatching centres. However, SCOPF is a complex optimisation problem for large practical power systems, mostly due to its highly non-convex nature. This study aims at changing highly non-convex SCOPF problem to a convex one. In this way, SCOPF can be solved with much less computation burden and more optimal solutions can be obtained for it by means of commercial solvers. For this purpose, the non-convex terms of SCOPF model (for instance, the terms associated with the valve loading effects of units and AC network modelling) are first reformulated using Signomial functions based on Taylor series. Then, the Signomial SCOPF formulation becomes convex by means of power transformation techniques. The constructed convex SCOPF formulation can be easily solved to obtain its optimal solution. The proposed solution approach is tested on well-known IEEE 30-bus, 118-bus, 300-bus and the polish 2746-bus test systems and its obtained results are compared with the results of several other SCOPF solution methods and published literature figures.