Background
On September 1, the Pakistan Mera DC project invested and constructed by the State Grid Corporation of China was officially put into commercial operation. The Mera DC project adopts the±660kV DC transmission technology with China's independent intellectual property rights, with a transmission capacity of 4million kW. Two converter stations were built near Lahore, Pakistan's second largest city, and Hyderabad, Pakistan's sixth largest city. The DC transmission line is 886 kilometers away, with a total of 1973 transmission towers, There are deserts, wastelands and other harsh terrain, and there is no communication signal in some areas, so it is very difficult to patrol.
Since it was put into commercial operation on September 1st, 2021, with the careful operation of the Chinese team, good economic benefits have been achieved, but there are also various problems such as difficult daily inspection, insufficient inspectors and poor on-site working environment. It is urgent to realize the function of Long-range Intelligent Inspection of DC lines through technical means, so as to timely find hidden dangers such as theft, strong winds and hanging foreign objects on the site.
Challenges
● The overall operation and maintenance level of transmission lines is not intelligent and inefficient
● Mera DC line has high demand for high-density inspection
● Untimely discovery of hidden dangers in the channel
● Insufficient strength of operation and maintenance personnel
● There are many hidden dangers in transmission channels, which are difficult to manage and control
● Pakistan is politically unstable and various security incidents are emerging one after another
Solutions
The intelligent visual inspection system of transmission line receives the on-site situation at the first time and provides solutions by means of visual monitoring, image intelligent analysis, equipment information management, hidden danger management, SMS directional group sending and other information technology means, so as to minimize the operation and maintenance costs of human and material resources and realize the visual real-time monitoring and management of channel hidden dangers. Focusing on the prevention of off-line construction, mountain fires, trees, foreign matter short circuit, bird damage and other external damage events, and taking the construction of a three-level patrol system combining specialty, territory and the masses as the guarantee, modern intelligent online monitoring means are adopted to analyze and compare the background data of the channel hidden danger types, and timely transmit the data to professionals, so as to realize the whole process visual operation and maintenance intelligent management of power grids, equipment, personnel and hidden dangers.
(Picture:Objective system of visual operation and maintenance management system for transmission line channel)
The main workflow of transmission line channel visual operation and maintenance management is as follows: the staff found the hidden danger of channel external force destruction in the daily inspection and centralized hidden danger troubleshooting, the professional management personnel verified and confirmed on site, and the hidden danger points were installed with visual monitoring devices to monitor the hidden danger in real time and collect data. In order to further support professionals' ability to identify hidden danger types and better arrange various on-site disposal work, functions such as visual monitoring module, image intelligent analysis module, equipment information management module and hidden danger management module are integrated in the background intelligent server to collect a large amount of channel operation and maintenance information, which can realize multi-dimensional data summary.
Network layer construction
According to the network conditions in different erection areas, in order to meet the network transmission requirements of equipment and strictly comply with the normative requirements of information security, the scheme adopts the method of mobile 4G plus wireless bridge for networking.
DC lines are mostly located in the desert and cannot communicate wirelessly through the operator's network. Therefore, the problem of signal weakness caused by no signal or blocking by trees, mountains, etc. and signal passing through towers can be solved through wireless bridges.
(1)Signaled area:
Pakistan's local 3g/4g mobile network transmission is adopted, and the mobile card signal system is compatible with that in China. In order to ensure normal use, Pakistan can send the mobile card to the domestic company for network test in advance.
(2)No signal area：
The wireless bridge mode is used for remote transmission and coverage of wireless network. The bridge is composed of transmitter and receiver, and the transmission distance can reach 5km-80km. It needs to be designed and selected according to the actual situation on site.
Visualize online platform functionality
The system adopts b/s architecture and provides a variety of standard interfaces for easy use and data interaction。
The main functions are as follows：
1. Line channel visualization: maps and charts are combined to fully display the device distribution, line operation conditions, asset operation and maintenance, etc. big data reports are exported with one click, and the main functions are reached with one click.
(Picture:Senter's visualized management system of transmission lines)
2.Visualization of equipment distribution: locate the position of front-end equipment to realize the visualization of monitoring point distribution.
3. Image rotation: all rotation and warning rotation can be carried out, conditional rotation can be carried out according to the line, key grouping and other information, and the rotation speed and screen layout can be freely set. It can directly take active photos and push through wechat. Quickly and intuitively patrol the latest situation of each monitoring point and deal with it directly.
4. Analysis and warning: conduct intelligent analysis of pictures, use contrast method + deep learning to achieve situational understanding, process pictures efficiently and accurately, upload pictures that may have hidden dangers, and filter normal pictures. According to statistics, it can filter about 95% of the normal pictures and realize no missing and low false alarm, which greatly saves the workload and flow of patrol inspection. The software platform has the function of manual comparison, manually confirming the alarm state twice to form a secondary filter. It provides the function of early warning history picture query, which can query the early warning and alarm history under different conditions.
Car identification
Foreign body identification
Smoke and fire identification
Staff identification
5. Key grouping: set key grouping according to different levels of hidden danger points, pay special attention to hidden danger points, and operate for key grouping parts in line channel visualization and picture rotation inspection.
Effects
Extend the manual inspection cycle and save operation and maintenance costs
At present, the traditional line operation and maintenance mode is mainly based on regular inspection and special inspection. The installation of hidden danger monitoring and early warning devices can realize daily inspection by means of remote inspection, which can reduce the attendance rate and personnel attendance rate, and save maintenance costs.
Find and stop hidden dangers of external damage in time, reduce line faults and economic losses
The transmission line channel stretches for more than 800 kilometers, and the channel environment is complex. There is the possibility of different potential external damage hazards at all times. In the high incidence section of external damage, through the terminal application setting, increase the image acquisition frequency, determine the abnormal situation in the monitoring area in the shortest time, and timely push the hidden danger pictures to the main management and technical personnel, so as to win more processing time for the staff, Avoid tripping and other accidents.
Social benefit analysis
If the external force damage of transmission lines is not found and handled in time, it is easy to evolve into power failure, even tower collapse and other serious accidents, resulting in large-scale power failure and other serious social adverse effects.
In traditional inspection, inspectors need to inspect key areas with high density to avoid the occurrence of potential external damage. Even so, during the short time that the inspectors leave the scene, there is still the possibility of external damage events, which cannot achieve the purpose of real-time monitoring. After installing the anti breaking online warning device, the hidden danger can be found at the first time, the remote control can be carried out at the first time, the hidden danger points can be shouted to stop work, the offline violations can be stopped at the first time, and the nearby wire guards can be notified to the site for monitoring in the shortest time, waiting for the on-site disposal of professional operation and maintenance personnel.