Calculation Software and Safety Analysis for Live Working of ±800kV Qishao Ultra High Voltage Transmission Line

In the power system, live workers need to complete various tasks such as heat treatment of the draft plate in a strong electric field. The inaccurate estimation of the wire load increases the labor load of the operators and can cause safety accidents such as wire disconnection and grounding short-circuit. This paper proposes a set of simple and easy-to-use live working mechanics calculation software to assist the dynamic analysis of the live working load of transmission lines, rationally select working tools, and improve the safety of live working.


Introduction
In the power system, live work is a special work with "high risk, high altitude, high voltage, and high technology". Live workers need to complete various tasks in a strong electric field, such as insulator replacement, hardware replacement, wire repair, foreign body removal, and heat treatment of the drainage plate. Therefore, engineers and technicians engaged in live work need to have knowledge of both electricity and mechanics. Before each operation, the engineer needs to calculate the electrical safety distance and line mechanics according to the on-site operation situation to demonstrate the feasibility of this work and form an operation plan to guide the work.
However, traditional calculation methods may cause incorrect calculation results due to their approximation and complexity. Inaccurate estimation of wire force (vertical gravity or horizontal pulling force) results in the selection of tools that are too large or too small, which increases the labor load of the operators. Furthermore, due to the huge workload of traditional calculation methods, work efficiency is seriously reduced. When urgent repair operations are needed, the emergency response time is extended.
Therefore, it is necessary to develop a set of easy-touse, accurate analysis and calculation results of live work safety analysis and mechanical calculation software. The software can calculate the electrical and mechanical parameters of live working lines on transmission lines. The feasibility of the operation can be analyzed, and the operation tools can be selected reasonably. It can improve the safety and work efficiency of live working, which is of great significance to the majority of live working personnel.

Functions and principles of the software
The working conditions are carried out under normal weather, no ice is required, and the wind speed is not greater than five levels.
In the relevant calculations, only the weight of the wires and fittings and the load caused by wind pressure are considered

Self-weight load of transmission wire
cross-sectional area of the wire.

Wind pressure P
The wind pressure on the wire is caused by air movement energy. The horizontal wind pressure in the vertical line direction is: 2 2 sin (9.8N) 16  -coefficient of uneven wind speed 1.0, wind speed 10m/s, F -The projection surface of the wind surface on a plane perpendicular to the wind direction,  The horizontal angle between the wind direction and the wind

Total load on a single sub-conductor is
where n is the number of split wires, unit root.

Calculation and Analysis of Forces on Tension Insulator Replacement
Suppose the temperature under known meteorological conditions is m t , the specific load is m g , the stress is m  , and the temperature under the meteorological conditions to be determined is n t , the specific load is n g , and the stress is n  , then the wire state equation is The tensile force of the insulator is = n T S  . where:α-the thermal expansion coefficient of the wire; β-the elastic elongation coefficient of the wire, 154×10 -6 (mm 2 /9.8N); l -represents the span (m).

Force when handling wire and ground wire broken strands
According to the conductor stress, specific load and air temperature before and after the unmounted ladder (flying car), the following state equation is used to calculate the conductor stress after the flying car is suspended.
The sag of the ground wire of the suspension ladder (flying vehicle) in the continuous gear can be calculated by the following formula.

Safety distance analysis
According to different operation methods, workers choose different paths to enter the electric field. According to the provisions of Q/GDW1799.2-2013 "State Grid Corporation of Electric Power Safety Work Regulations Line Part", the safe distance between the operator and the live body during live work shall not be less than 6.8m; the safe distance between the equipotential personnel and the grounding body should not be Less than 6.8m. The combined gap of operators during the process of entering the electric field shall not be less than 6.6m. Therefore, it is necessary to calculate and verify the safety distances and combined gaps of different work methods to meet the requirements to carry out live work.

Calculation process
Comparing the content of the work items, tool selection and analysis and calculation process, etc., the frequently carried out work items are divided into 5 categories. Each type of research content and technical route are as follows.

Computing software interface
According to the calculation principle and calculation process, the calculation software is compiled, and the design function interface is as follows.

Conclusion
The research and development of this article is to develop a software calculate the electrical and mechanical parameters of live working lines on transmission lines. The feasibility of the operation can be analyzed, and the operation tools can be selected reasonably. It can improve the safety and work efficiency of live working, which is of great significance to the majority of live working.