Congestion management considering voltage security constraints

This paper describes a method of alleviating network congestion while maintaining system voltage security. To alleviate network congestion, the system operator (SO) typically acts in many ways including the rescheduling of generation or load. However, voltage security might worsen, especially under circumstances involving heavy loads or contingencies. Generation and load rescheduling changes power flows in networks and system voltage profiles. Furthermore, this will affect the voltage security margin. To ensure voltage security, the SO must manage reactive power effectively and economically under the prevailing electricity industry environment. The proposed method is tailored for such a scheme. The proposed objective function is designed to minimize congestion charges and reactive power charges considering voltage security constraints. Continuation power flow (CPF) is applied and coordinated with AC optimal power flow (OPF) using piecewise linear cost functions. Computational analyses of the IEEE 30-bus and 57-bus systems, shows that convergence can be achieved within a few iterations. Not only is network congestion relieved, but voltage security is also maintained.