Study on Improving Transmission Line Current Capacity Based on Line Temperature Monitoring
|Keywords||Transmission line Current capacity Singular factor modification Multi-factor modification Identification method|
As the continuous fast development of our economy, electricity consumption for commercial and residential daily use is increasing sharply, that our nation has to invest great funds for the construction and reconstruction of transmission line, however, the new construction of transmission line is constrained by a lot of factors(such as the long term, the limited funds and line road, and the corresponding environmental problems). So how to improve the transmitting capacity of existing infrastructure have drawn great attention from more and more specialists and learners. For a long time, on the issue of improving transmitting capacity, a lot of work is done focusing on the research of the control mode for power grid operation, dispatching mode of electricity power and the qualities of transmitting elements such as material and structure. But recently, some learners suggest that one important factor of thermal load ability-maximum allowable current capacity, whose impression and solution is always under conservative circumstances, and if the surrounding weather conditions can be measured, the maximum allowable current capacity can be calculated dynamically, which will improve line utilization ratio and release line potential ability. But it is the complexity of weather factor measure system that made this method can’t be used widely. Under this circumstance, an easy way to evaluate line current capacity will make great sense for release the potential current capacity of existing transmission line, and decreasing the urgent need for new construction of transmission line, as well as the power grid security and economical operation.In the paper, on the basis of comparing two type of criteria for transmitting capacity calculation, details and analysis is shown on the impression and calculating way of four types of heat generation and dissipation mechanism.On the basis of simplified Morgan Equation, an introduction of calculation method is made, and based on the dynamical heat balance equation of transmission line, an heat generation and dissipation dynamic simulation mode is constructed, experiments show that the simulation mode can well reflect the temperature changing process of transmission line while real environmental factors changes.The paper proposes an current capacity evaluation method based on the real-time line temperature detecting and weather factor broadcast information. This method attributes the inaccuracy of weather broadcast information to a singular factor using line temperature and current. Conservative evaluation method is applied to calculate the current capacity of transmission line. The method is low-cost and easy applied, it shows both theoretical and practical values which will help it to be widely accepted as a good way to improve current capacity dynamically.At last, considering the inaccuracy and conservatism of singular weather factor modification, the paper proposes a multi-factor modification method which take the line current and temperature as input and output of a dynamic system. Through the identified weather factors the current capacity is calculated. Solution and improving method is given for the problems in the identification. The simulation proved that this method can effectively improve the line current capacity.