Voltage stability constrained line-wise optimal power flow

• Published in: IET generation, transmission & distribution Vol. 13; no. 8; pp. 1332 - 1338
• Main Authors: Mohamed, Amr Adel, Venkatesh, Bala
• Format: Journal Article
• Language: English
• Published: The Institution of Engineering and Technology 23.04.2019
• Subjects: bus voltage magnitudes; bus‐wise power balance equations; line‐wise power balance equations; load flow; nonlinear solution space; operating constraints; optimal power flow; optimisation; power markets; power system; power system dynamic stability; power system stability; Research Article; simple line‐wise OPF; voltage stability constrained line‐wise; power system stability; simple line-wise OPF; bus voltage magnitudes; power system; optimal power flow; nonlinear solution space; line-wise power balance equations; operating constraints; bus-wise power balance equations; optimisation; voltage stability constrained line-wise; power system dynamic stability; power markets; load flow
• ISSN: 1751-8687; 1751-8695
• DOI: 10.1049/iet-gtd.2018.5452

The purpose of optimal power flow (OPF) is to optimise an objective function subject to a set of operating constraints. It remains an active research area because of using the bus-wise power balance equations, which leads to a non-linear solution space, resulting in OPF yielding local optimal solutions, thereby causing significant economic loss. In this study, first, a new line-wise OPF (LWOPF) formulation is proposed. Thereafter, a maximum loadability factor, as a voltage collapse indicator, is derived and combined with LWOPF constraints to form a voltage stability constrained LWOPF (VSCLWOPF) model. As the line-wise power balance equations are based upon the square of voltage magnitudes, it results in significant improvement in the solution space and lower-order terms in all computational steps. The LWOPF and VSCLWOPF formulations, are solved using non-linear optimisation technique, tested on several benchmark and real power systems. Results show that the proposed LWOPF is accurate, provides monotonic convergence, and scales well for large systems. It provides a better solution and is consistently faster, up to twice the speed of MATPOWER, due to reduced computational needs. Results of VSCLWOPF show that, for the same voltage stability level, the solution costs less than that obtained by classical bus-wise OPF.