Risk-based security assessment of transmission line overloading considering spatio-temporal dependence of load and wind power using vine copula

Location of wind power plants and demand centres are not always close by; hence, the transmission of energy puts a burden on existing grid infrastructure. This unwanted burden necessitates transmission lines to operate more and more frequently close to their operating limits. To alleviate such situations, this research addresses the advantages of modelling spatio-temporal dependence of load and wind power using vine copula. Probabilistic AC optimal power flow is performed on a modified IEEE 39-bus system with significant wind penetration. Real load and wind power data from a U.S. utility is mapped onto the test-case to achieve realistic results. Load flow calculation can help in performing steady-state voltage and overload evaluations for post-disturbance system conditions. Because the security level of a power system is determined by the likelihood and severity of security violation. In this research, the probability of line overload is calculated from load flow and the severity function describes the risk of line overloading. Two case studies depicting future operating conditions of massive wind power penetration with reduced fossil fuel and nuclear power generation are considered. Simulation results prove the advantage of addressing spatio-temporal dependency to quantify the overload risk index, which is treated as a security indicator.