What is a straight pole tower
The straight pole tower refers to the pole tower used for the straight section of the overhead line. The wires are suspended by hanging clips, pin-type or column-type insulators. The design form of the straight tower of the AC UHV transmission line mainly adopts the cat head tower, and the conductors are arranged in the middle phase “V” string and the side phase “I” string. The vertical distance between the middle phase conductor and the lower phase conductor is about 16m, and the horizontal distance between the two phase conductors is about 30m. Therefore, the line corridor can be reduced to a certain extent. In order to save the line corridor and reduce the cost of dismantling, this kind of cathead linear pole tower is usually adopted.
Tower
The main form of linear pole tower is cat head tower. Except for some towers near the UHV Jingmen Substation and the large span of the Han River, other towers are all in the form of wine glass towers. Many plains and hilly areas are Maotou Pagodas. Let's analyze the cat head linear pole tower.
According to the operating experience of 500kV transmission lines, in addition to the design wind speed, the vertical load in the gear and the tower clearance, the wind deflection problem should be emphasized when calculating the wind deflection angle of the insulator string. In the actual operation of the 500kV line, due to the excessive wind deflection angle, there is a phenomenon that the wires discharge to the main body of the linear pole. The key to the calculation of the wind angle is the value of the wind pressure coefficient, which will be discussed based on the operation and maintenance experience of the ultra-high voltage transmission line.
Tower
Due to the poles and towers of the AC UHV line, the span, vertical span and horizontal span are also relatively large, and the line does not pass through the micro-weather area. Generally, the possibility of wind deviation on AC UHV lines is relatively small. In the practice of long-term operation of 500kV lines, auxiliary measures such as the installation of heavy hammers have been adopted, which have a certain effect on restraining wind deviation. On the other hand, in the design of cathead linear pole tower, for the division and division of the meteorological area along the line, corresponding technical measures can be taken for each section or even the specific situation of each file, and the safety factor and design of the line The remaining components can be increased appropriately.
Since the occurrence of wind-guiding faults is usually random, the influence of micro-topography on wind speed and the laws of disastrous weather such as strong local winds should be further studied, so as to improve the level of wind direction and reduce the wind deflection of transmission lines with straight poles.
