TRANSMISSION NETWORK EXPANSION PLANNING CONSIDERING THE N – 1 SECURITY CRITERIA AND REACTIVE POWER FLOWS

Abstract

Transmission network expansion planning (TNEP) is an essential study area in power systems. The TNEP problem is often developed using the direct current power flow (DCPF) method. However, this approach takes no account of the power loss and the effect of reactive power flows. In addition, ensuring the security of power systems for a single outage of any system element, known as the N‒1 security criteria, plays a vital role in planning and operation problems. This paper presents a mixed-integer linear programming (MILP)-based method with the aim of optimizing the transmission grid topology considering power loss, reactive power flows and the N‒1 criteria. The adjustment technique of branch limits is deployed with a view to the incorporation of the influence of reactive power flows. The iteration technique is proposed to consider the N‒1 criteria in the network planning process. The evaluation of the proposed method is implemented on an IEEE 24-node transmission system, in which the MILP model is solved using the CPLEX tool under GAMS programming language, and the N‒1 contingency analysis is performed using POWERWORLD software. The planning results show that 19 transmission lines with a total investment of 86.7 M$ need to be built for the security operation of power systems according to N‒1 criteria.