Spacers are key components that are used to support high voltage conductors in gas-insulated substations or gas-insulated lines. The analysis of the surface charge patterns on spacers remains a difficult task, which requires a comprehensive understanding of the physical mechanism of the gas-solid interface charging phenomenon. In this letter, we reported a field dependent property of surface charge accumulation patterns on spacers under DC stress. We verified this finding through experiment, and further, we put forward a field-dependent charging model based on dominant charge transport behavior under different electric fields. It was found that the charging characteristics of the spacer are dominated by the Ohmic conduction from the volume below an electric field of 2.5 kV/mm. When the electric field stress is higher than 2.5 kV/mm, the charging property of spacers is dominated by the enhanced gas ionization according to Townsend's law. The correctness of this model was verified by surface charge measurement results in literature studies, and a method for determining the dominant mechanism of charge accumulation under different electric fields was proposed.Spacers are key components that are used to support high voltage conductors in gas-insulated substations or gas-insulated lines. The analysis of the surface charge patterns on spacers remains a difficult task, which requires a comprehensive understanding of the physical mechanism of the gas-solid interface charging phenomenon. In this letter, we reported a field dependent property of surface charge accumulation patterns on spacers under DC stress. We verified this finding through experiment, and further, we put forward a field-dependent charging model based on dominant charge transport behavior under different electric fields. It was found that the charging characteristics of the spacer are dominated by the Ohmic conduction from the volume below an electric field of 2.5 kV/mm. When the electric field stress is higher than 2.5 kV/mm, the charging property of spacers is dominated by the enhanced gas ionization according to Townsend's law. The correctness of this model was verified by surface charge measurem...

Field-dependent charging phenomenon of HVDC spacers based on dominant charge behaviors

The electric field distributions along gas-solid interfaces determine the reliability, lifetimes and sizes of gaseous insulated switchgears/pipelines (GIS/GIL), which also affect the reliability of power systems. In this study, the characteristics of steady and transient electric field distributions were first introduced, followed by the concept of functionally graded materials (FGMs). The development histories of FGM applied in electrical engineering and the related optimisation methods were described in detail. The field regulation effect and fabrication technology of different FGM insulators were also compared. To overcome the limitations of traditional FGM insulators, the design of surface FGM (SFGM) was proposed, together with their preparation methods and electrical performance. Furthermore, the future development prospects of FGM and SFGM insulators for compact GIS/GIL were summarised.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/hve.2019.0327

Promising functional graded materials for compact gaseous insulated switchgears/pipelines

Surface charge accumulation on the spacers is one of the key issues restraining the development of HVDC GIS/GIL. The precise measurement of surface charge properties provides the basis for further study of the surface charge transport mechanism as well as the charge-induced flashover mechanism under DC voltage. In this study, the authors discuss their perspective on the current status, development needs and potential developing orientation of surface charge characterisation techniques. Different surface potential measurement methods and charge inversion algorithms are reviewed regarding the previous studies and future research needs. Drawbacks and outlooks of surface charge measurement techniques are also discussed with the background of laboratory experiment results and on-site measurements. It is hopefully that this study can serve as a useful guide reference for researchers within the same research field. More importantly, it is authors’ hope that this study can inspire some novel ideas for readers into developing of more accurate and scientific interface charge characterisation techniques.

Gas–solid interface charge characterisation techniques for HVDC GIS/GIL insulators

The regulation mechanism of SiC/epoxy coatings on surface charge behavior and flashover performance of epoxy/alumina spacers

https://iopscience.iop.org/article/10.1088/1361-6463/ab6d1a/pdf

Surface charge transport behavior and flashover mechanism on alumina/epoxy spacers coated by SiC/epoxy composites with varied SiC particle size

Effects of surface roughness on surface charge accumulation characteristics and surface flashover performance of alumina-filled epoxy resin spacers

Surface charge accumulation on spacer is an important factor to cause surface flashover. An experimental set-up is established to measure surface potential over a truncated cone-type spacer under DC voltage in SF
 6
 gas at atmospheric pressure using a Kelvin vibrating electrostatic probe. The surface charge density is calibrated based on multipoint measurement technique, which takes the influence of electrostatic probe into account. The experimental results show that surface charge distribution patterns can be divided into three classes including centrosymmetric distribution, spot-like distribution, and cloud-like distribution. The symmetrically distributed charges are injected by electrode, which migrate along spacer surface through the surface conductivity. While the charges showing spot-like and cloud-like distribution are generated by the ionisation of SF
 6
 due to local electrical field concentrated. Besides, the hetero-charges are more easily to be saturated with different charging durations and the polarity of the net charge is the same as that of applied voltage.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-smt.2017.0325

Surface charge distribution patterns of a truncated cone-type spacer for high-voltage direct current gas-insulated metal-enclosed transmission line/gas-insulated metal-enclosed switchgear

The invention discloses a high-voltage switchgear onsite opening automatic operation robot. The robot comprises a power supply, a master control computer, a wireless signal transmission apparatus, a remote control apparatus, an arm, an arm driving system, an end execution mechanism, an end execution mechanism control system, a walking driving system, a walking driving mechanism, a machine vision system and an image processing system, wherein the master control computer, the arm driving system, the end execution mechanism control system and the walking driving system are connected with the power supply; and the remote control apparatus emits control commands to the wireless signal transmission apparatus, and the wireless signal transmission apparatus transmits the control commands to the master control computer. According to the invention, through cooperation with a manual whole-course monitoring system, rotation of a switchgear emergency opening locking handle can be completely automatically operated, a switch tripping button is pressed, switch onsite tripping is realized, entry and exit operation of a breaker dolly is executed, and another problem of manual near-distance operation of a high-voltage switchgear is solved.

High-voltage switchgear onsite opening automatic operation robot

The invention discloses an analog measuring device and method for the surface potential of an insulator in a GIL. The analog measuring device comprises a closed cavity, the insulator, an electrostaticprobe and a high-voltage electrode guide rod. Air inlet and outlet are formed in the cavity wall surface of the closed cavity. A guide rail is installed in the closed cavity, and a first shielding cylinder and the insulator are arranged at one end of the guide rail. The insulator is rotatably disposed in the first shielding cylinder through a high-voltage electrode support rod. A second shieldingcylinder is arranged at the other end of the guide rail, and the second shielding cylinder is internally provided with the high-voltage electrode guide rod. The first shielding cylinder and the second shielding cylinder are both grounded. The electrostatic probe is movably disposed in the closed cavity, and the electrostatic probe can measure the surface potential of the insulator. The analog measuring device can complete the analog measurement of the surface potential of the insulator in the high-pressure closed cavity, and can simulate the working environment of the insulator of the GIL inreality, the measurement result is high in credibility, and theoretical guidance can be provided for actual production.

Analog measuring device and method for surface potential of insulator in GIL

The utility model discloses an electric operating robot of transformer substation, including caterpillar base plate, elevating system, ram and sub - robot, sub - robot connection ram, the ram is through setting up the top of connecting elevating system at the base of its lower part, elevating system is connected to the hydraulic system of setting in caterpillar base plate through the pneumatic cylinder, and hydraulic system connects the generator, and the internal -combustion engine is connected to the generator, sub - robot is provided with motion arm, built -in sub controller, sub - robot is connected to controller and the generator that sets up in caterpillar base plate, the internal -combustion engine sets up in caterpillar base plate, provides power for caterpillar base plate's motion, ram, hydraulic system and caterpillar base plate are still connected to the controller to connect the remote controller through wireless transmitting device and wireless receiving device, the utility model is suitable for a live overhaul of transformer substation, the operating efficiency is high, the operation security is high to can guarantee service reliability.

Li Kefeng

Papers

Effects of surface roughness on surface charge accumulation characteristics and surface flashover performance of alumina-filled epoxy resin spacers

Surface charge distribution patterns of a truncated cone-type spacer for high-voltage direct current gas-insulated metal-enclosed transmission line/gas-insulated metal-enclosed switchgear

High-voltage switchgear onsite opening automatic operation robot

Analog measuring device and method for surface potential of insulator in GIL

Electric operating robot of transformer substation