A. Bagheri - Department of Electrical Engineering, Faculty of Engineering, University of Zanjan, Zanjan, Iran
A. Rabiee - Department of Electrical Engineering, Faculty of Engineering, University of Zanjan, Zanjan, Iran
S. Galavani - Planning and Research Deputy, Zanjan Regional Electric Company, Zanjan, Iran
H. Yassami - Planning and Research Deputy, Zanjan Regional Electric Company, Zanjan, Iran
A. Moeini - Planning and Research Deputy, Zanjan Regional Electric Company, Zanjan, Iran

Transmission lines switching and tap adjustment of power transformers are short-term alternatives to enhance the flexibility of power system operation. By a proper implementation of these alternatives, the operational problems such as lines congestion, bus voltage violations and excessive power losses can be alleviated. Traditionally, these two alternatives are applied separately due to the complexity of their simultaneous implementation as well as their coordination. In this paper, a DIgSILENT-based improved particle swarm optimization (IPSO) algorithm is proposed to implement the transmission switching and coordinated voltage control of power transformers, concurrently. The IPSO is implemented in DPL environment of Powerfactory-DIgSILENT, as a powerful software package commonly used by the electrical utilities. The proposed approach is applied to IEEE-۱۴ bus system and the real transmission network of Zanjan Regional Electric Company (ZREC) located in Iran, in different scenarios considering all the existing practical constraints. The obtained results verify the effectiveness of the presented approach.

Transmission switching, OLTC’s tap adjustment, Improved PSO, DIgSILENT