Forecasting For Failure Probability And Research On Emergency Strategy Of Transmission Lines In Ice Strom

Since the large-scale construction of overhead transmission lines around the world, the damage of transmission lines and towers caused by ice storms occurs frequently. The icing disaster of transmission facilities will be happened extensively when the ice thickness is thicker, consequently, the transmission systems in some areas lost their functions completely and severely threat to power system security. As a result, huge financial losses were caused. Therefore, it is essential to study the ability of transmission facilities to withstand their impacts. Based on generalized Pareto distributions (GPD) of the extreme value theory (EVT), extreme machine learning and the Copula functions, the probabilities models of transmission line damage and tower collapse are firstly derived, based on this, the anti-icy and ice melt strategy are proposed correspondingly.Ice load and wind load of transmission lines is intimately related to meteorological condition, considering the randomness of meteorological conditions during ice storms, the probability models of freezing precipitation and wind speed are firstly derived based on the generalized Pareto distributions (GPD) of extreme value theory (EVT). Then the calculation models of ice load and wind load of transmission lines are employed to derive the probability distribution between the ice loads and wind loads on both transmission lines and towers. Furthermore, by taking into account the influence of varying meteorological conditions on probability distribution of ice loads and wind loads, the real-time probability distribution of ice loads and wind loads are developed base on datas training and learning of the ELM network, which meteorological conditions as the input variables. The validity and accuracy of the proposed model is verified by comparing the numerical results given by the model with the historical data, which indicates that GPD is an appropriate distribution function for modeling freezing precipitation and wind speed, the ELM based predictor can appropriately model the nonlinear relationship between the meteorological variables and the distribution parameters of wind load and ice load on electricity transmission facilities.The accidents of transmission line break down and tower collapse are caused by ice load and wind load, in an ice storm, the ice load and wind load on transmission facilities are influenced by identical meteorological factors, they are thus correlated. To accurately estimate the probabilities of transmission facility damages, it is necessary to consider the joint probability distribution of ice load and wind load in our model. In this paper, the copula functions are employed to model their correlation, thereby, the probability of line break down and tower collapse are accurately calculated by considering the unsymmetrical correlation between the ice load and wind load. Based on the historical data, the numerical results indicate that the unsymmetrical probabilistic correlation between the ice load and wind load on transmission facilities is appropriately modeled with the copula function, consequently, the combined loads impact of transmission lines and towers by ice load and wind load can be effectively analyzed, the probability of line break down and tower collapse are accurately predicted.Considering the severe icing and line break down and tower collapse accidents are occasioned by ice storm, In this paper, some researches on the anti-icy and ice melt of transmission lines are discussed, and emergency strategy of cladding ice transmission lines are presented, sequentially, reasonable contingency plans can be formulated and implemened to ensure the safe and reliable operation of the power transmission lines during ice storm.