1. Overview

1.1 Necessity

Power substation is responsible for the production and construction of power grid lines, electrical equipment in the station is close, lines are complicated, nodes, large transformers are numerous, is the key department of the power sector safety prevention. In order to ensure the safety of substation internal operation, a lot of manpower and material resources are invested every year.

Power network equipment

Unlike other industries, the electrical sector can not be interrupted at will in maintenance, which requires sufficient prediction before the accident -- before the accident to solve the fault, the emphasis is on the preventive patrol of substation equipment. The transformer system is responsible for the power transmission, and the high-voltage and high-current line works for a long time. Even the excellent insulating medium will have unexpected problems and lead to accidents. Most of the accident is caused by insulation aging, failure, its appearance is: in a few hours before the failure than the normal work of heat. Therefore, if we can accurately know the temperature distribution of the equipment in the site before the accident, we can control the operation condition of most of the electrical equipment.

1.2 Feasibility

The infrared thermal imager displays the infrared thermal energy in the form of thermal image by detecting the different infrared thermal energy radiated from the object surface due to different temperature. No matter the internal fault of power equipment (such as lightning arrester internal moisture) or the thermal fault of power connection point, the infrared thermal imager can be clearly displayed to timely find and locate the potential problems of power network equipment. The non-contact monitoring and measurement mode of infrared thermal camera is not affected by visible light, and can penetrate smoke, rain and fog and other measurement characteristics, which not only reduces the risk of workers' patrol inspection in dangerous operation areas, but also improves the monitoring and measurement efficiency of power system.

2. System Overview

The on-line infrared thermal imaging method can be used to measure the temperature of the power network, so as to observe the temperature measurement status through the network remotely in real time, locate the abnormal temperature components in time, and eliminate the potential hidden dangers.

2.1 System composition

When designing the thermal imaging temperature measuring system of power station, we designed the infrared thermal imaging instrument +NVR system solution.

Infrared thermal imager +NVR system solution: The biggest feature of this solution is all digitization. The front end uses infrared thermal imager to store video images and display them in real time through the display. The biggest characteristic of this set of solutions is that the system is all digital, convenient networking, late point expansion and system upgrade convenience.

Infrared thermal imaging of power grid equipment

Infrared thermal imager can control zoom, automatic focusing, adapt to high and low temperature operation, infrared thermal imager has environmental temperature compensation function, the full operating temperature range temperature drift is less than ±2℃.

The visible light camera is used in conjunction with the infrared thermal imager to adjust its Angle of view to keep consistent with the infrared thermal imager. It is convenient to observe the normal imaging and thermal imaging of the same object at the same time, and can find the hidden trouble more intuitively and retain the image data.

Visible light camera and infrared thermal imager should be integrated into the same protective cover, which can not only save installation space but also make wiring neat.

2.1.2 Transmission network

Transmission mode: In order to reduce signal interference under the influence of strong magnetic field inside the substation and ensure the stability of signal transmission transmission network, optical fiber is selected as the cable of transmission network.

Network mode: network communication systems used in IP network technology, network, and can use network extending, the bridge

2.1.3 Background display and analysis module

For the power network online temperature measuring system, our company developed IRTool infrared monitoring software, which supports online observation mode and offline analysis mode. It can add multiple temperature measuring objects, track high and low temperature, generate temperature curve in real time, alarm temperature and generate report, etc., with rich functions and easy operation.

3. Hardware Equipment Selection

3.1 Imaging principle

Infrared thermal imager uses infrared detector and optical imaging objective lens to receive the infrared radiation energy distribution pattern of the target to reflect on the photosensitive element of infrared detector, so as to obtain the infrared thermal image, which corresponds to the thermal distribution field of the object surface. The popular infrared thermal imager refers to the object emitted invisible infrared energy into visible thermal image. Different colors on the top of the thermal image represent different temperatures of the object being measured.

3.2. Lens selection

As an optical product, the selection of lens resolution focal distance determines the spatial resolution, field of view Angle, identification distance and other indicators. Therefore, the selection of thermal imager lens should be based on the size of the observed object, the observation distance and so on.

The model and parameters of infrared thermal camera are as follows:

Model parameters

Model X640D X384D X160A

Infrared resolution: 640x480 384x288 160x120

The pixel size is 17um

30 hz frame frequency 50 hz

NETD 50 or less mk @ 25 ℃

Working band 8~14um

See "Lens List of Yoseen X Series Thermal Imager" for field Angle.

Angular resolution

The temperature measurement range is various, -20 ~ 150℃, 10 ~ 50℃, 0 ~ 300℃, etc

The temperature measurement accuracy is ±2℃ or ±2%, which can be improved to ±0.4℃

3.3 Cradle Head and Cover

According to the changeable installation environment of the power on-line temperature measuring infrared thermal imager, we have added the installation accessories such as cradle head and cover for the thermal imager. The monitoring cradle head adopts the digital medium-load cradle head to realize the cradle head can rotate 360 degrees, the custom cruise, supports the Angle return function. The shield is used to deal with the harsh environment, waterproof, dustproof, anticorrosion, salt spray, etc.