An Application of Generator Units and ULTCs in Reactive Power Management in a Large Scale Power System

One of the most important issues in electricity power systems, regulated or deregulated, is reactive power management. Voltage stability, voltage profile and losses optimization are some of objectives in reactive power management and control. Under Load Tap Changer (ULTC) transformers and generator units are two common instruments which are using in reactive power management and control. In this paper, simultaneous optimization of voltage stability, voltage profile and active losses as an objective function is considered. A new method for ULTC and generator candidate selection as well as implementation method in a large scale power system is demonstrated in this paper. Reactive power management is a large non-linear problem, in which applying classic optimization methods are not efficient and sometimes are impossible in a large scale power system. In this paper, we introduce a new method for adjusting regulating voltage for selected ULTCs and generators, as well as tap position of ULTCs to achieve to optimum voltage stability, voltage profile and losses in the system. After fully explained formulation, we proposed our method on an IEEE standard test system, then we implement our method in Iranian large scale power system and demonstrate the results. The method could be used in power systems operation and it may be interesting for ISO (independent System Operators) to be used in their everyday power system operations.