A congestion index considering the characteristics of generators & networks

The connection of renewable generation into transmission network contributes a lot to provide green electricity and ensure energy security. However, the current congestion management schemes and related cost allocation methods fail to fairly treat different types of generators, such as wind farms with low load factor and conventional thermal plants with high load factor. In this paper, a congestion index which is defined as the annual congestion cost of unit transmission line, Annual Congestion Unit Cost (ACUC), is first introduced. ACUC identify different generators with their installed capacity, load factor and electricity price. Moreover, the calculation of ACUC learns from the idea of MW·km and the congestion cost is allocated by Power Transmission Distribution Factor (PTDF). Therefore, ACUC consider the characteristic of both generators and networks. The application of ACUC is demonstrated by DC Optimal Power Flow. The case studies based on a three-bus power system & an eight-bus power system are undertaken in this paper. Simulation results show that ACUC can effectively locate the congested transmission branches and with the reinforcement of these branches, the total congestion cost can be extremely reduced.