Transmission network expansion planning in the competitive environment, A reliability based approach

Transmission network plays a pivotal role in the liberalised power markets. In fact, the necessary fair environment due to competition for the participants in the power market would be provided only by a suitable and well-designed transmission network. In this context, transmission network expansion planning studies play an important role to optimally address this issue. Although extensive studies have been done in this area, each has its relative strengths and weaknesses depending on the scope of the study reflected on the objective function of the planning problem. The objective function of the transmission network expansion planning proposed in this study is to minimize the expected value of interruption cost in the network for different consumer segments, while satisfying the security constraints of the system, i.e. - transmission lines capacity, generation capacity, and upper and lower bounds of bus voltages. The solution is to improve the transmission network reliability taking into account the rate of uncovered consumer segments due to the lack of transmission capacity and finding the optimum alternatives of the transmission network expansion. The proposed methodology includes two steps as; Finding the existing candidates for transmission network expansion contributing to improve the transmission network reliability and Analysing the selected candidates for optimality according to the proposed objective function. The IEEE Reliability Test System (IEEE RTS) considered as a case study. Results show that the industrial customers, which have higher interruption costs in comparison to the household loads, require higher reliability levels and more redundancy.

I. Introduction

Deregulation in the power market has caused a great change in the relations and attitudes of the different parts in power systems. Due to changes in the rules, different parts of the power system would have gone out of the network management control and as the consequence they would have been decided by the private subsystems. These changing issues have caused more complications in power systems operational studies and of course power system planning as well. Transmission network is among one of these parts which are affected by the changes. The transmission network in the deregulated market plays a vital role in the creation of the non-discriminatory and competitive environment.