| By the end of the twelfth five year, State Grid Corporation of China plans to basically completed power network which looks UHV grids as the backbone grid, coordinated development of power at all levels, with information, automatic, interactive features of the strong and smart grid. Further improve the"West to East","North to South"the energy distribution pattern. With the continuing advance of power grid construction, especially the UHV grid have been built and put into operation, the national network of power system will be improved step by step. Meanwhile, the grid structure will also become more complex, the link between the regional power grids also become more closely. Therefore, whether the power system can operate safely and stably is the big problem which the power grid has to face to. In particular, how to avoid the ice storm on the power system caused serious damage under the extreme weather conditions. This paper presents a new idea which can effectively cope with ice and froze disaster of power system, and the theory offer to an important guarantee of the anti-ice and keeping power supply for power system.This paper proposes a forecasting model of high-voltage transmission line ice accretion growths which based on extreme learning machine, and describes n detail the basic principle and characteristics of ELM. Using ELM network model to get the relevant network parameters from the actual training of the ice data transmission lines. And select two typical wires in Hunan power grid 220kV as the study object. Using ELM model to give the ice growth predict of the wire of the two model. By comparison with the experimental measured value and predictive value of ELM model verify the accuracy of forecasting results.This paper comprehensively analyzes the heat balance the process of surface of iced conductors, and on the basis a critical current model of anti-icing to ice. Using the model this paper constructs calculates anti-icing critical current of two typical overhead conductors of Hunan power grid, and these forecasting results are compared with experimental determination value, the results show that the model establishes in this paper is feasible.Ice attaching on the surface of transmission lines is timely and effectively melted can greatly ease the disasters caused serious damage to power systems. Ice-melting methods by the traditional three-phase short circuit current and DC current have to outage ice-covered lines, and to a certain extent, reduce the reliability of power supply. In this paper, the feasibility of anti-icing and melting ice by load current is analyzed. This way established in this article can make transmission lines keep working, and the whole process will not produce short-circuit current, and easy operation. High-voltage transmission line in Hunan power grid is divided into 3 classes according to their function. Whether each type line is to meet the conditions of anti-icing and ice-melting by load current, and following analysis the stability of system after adjusting operation mode for according with the requirements. To ensure power system safely and steadily operate in the period of anti-icing and ice-melting. The paper focuses on ice accretion growth, anti-ice the critical current and melting ice by load current of high-voltage transmission lines, and carries related studies. Using a combination of theoretical and experimental way to prove the accuracy of the theoretical model. Research results presented in this article offer to reference values for preventing ice and froze disaster of power system, and provide a basis for making timely and accurate decision according to real-time ice conditions. |
PDF Full Text Request