High Voltage Switchgear Research Articles

Formulation design of a new type of epoxy resin-based insulating adhesive and research on its high temperature resistance

A series of new epoxy resin adhesives were prepared by low viscosity bisphenol A epoxy resin E-44 and E-51as the matrix, low molecular polyamide 650# and phenolic modified JT-3008 as the curing agent, silicon micro powder and calcium carbonate as the fillers. The gelation time, surface drying time and shear strength of the samples were deeply tested. The thermal decomposition temperature and high temperature resistance of the samples were determined by TG analysis. Meanwhile, the surface fracture morphology was observed by SEM. The results showed that a new kind of heat epoxy resin insulation adhesive with long gelation time and convenient construction and meeting the requirements of production adjustment was successfully obtained through the optimization design of the formula,. The new epoxy resin insulation adhesive showed excellent mechanical properties with 18.00 MPa shear strength, which can be used at 380 ℃ for a short period of time and 130 ℃ for a long time. The new adhesive developed in this paper can be widely used in high voltage switchgear and other insulation materials, which has good application prospects.

Prediction of Impulse Breakdown Voltage in Dry Air at High Pressure Using Volume-Time Theory

Dry air is promising as an alternative insulation medium for SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas in high-voltage equipment. Since its dielectric strength is about one-third of that of SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas, one of the most effective ways to apply dry air to high-voltage gas-insulated switchgears (GISs) is to further increase gas pressure. In this article, impulse breakdown strength of dry air at high pressure under quasi-uniform electric field is measured. Furthermore, the probability distribution of breakdown voltage is predicted using the volume-time theory in consideration of initial electron generation probability in gas gap and field electron emission from an electrode. The predicted distribution of breakdown voltage by the volume-time theory is in line with the experimental results.

Influence of breaking current and arc energy on SF 6 decomposition products under arcing conditions in high voltage switchgear

SF6 is widely used in high voltage switchgear due to its excellent insulation and arc extinguishing performance. It is an important method for fault diagnosis and electrical life assessment of SF6 switchgear to detect and analyze gas decomposition products. Breaking current and arc energy have a significant effect on the species and concentrations of SF6 decomposition products so relevant studies were carried out. A test platform for SF6 decomposition products of switchgear under arc discharge was built and a series of SF6 decomposition tests with breaking current of 0.8kA, 5kA, and 31.5kA were carried out on a 40.5kV SF6 circuit breaker. The decomposition components were detected by a gas chromatography. It has been found that the larger breaking current is, the more species of SF6 decomposition products are. When breaking current remains constant, the higher accumulated arc energy is, the higher concentrations of SF6 decomposition products are. After 31.5kA breaking test, the order of the generation amount of SF6 decomposition products is SOF2&gt;CF4&gt;&gt;SO2&gt;CO2&gt;&gt;C2F6&gt;SO2F2. The influence of breaking current and arc energy on SF6 decomposition products is clarified, which is important for the fault diagnosis and electrical life assessment of high-voltage SF6 switchgear based on decomposition products analysis.

Optimization of the internal shielding system in gas filled high voltage electric appliances with polymer insulation

In the article, the authors propose a technique for estimating the parameters of the electrical load for calculating the distribution of the electric field strength of a solid insulating structure of gas-filled high-voltage apparatus that have axial symmetry. This design is a support and insulating cover filled with SF6 gas as an internal insulating medium. This technique makes it possible to estimate the parameters of the electrical load (voltage and field strength) depending on the design features of the device and the shielding system that is used to equalize the electric field. The proposed method makes it possible to evaluate the effectiveness of the influence of the design parameters of the shielding system for gas-filled high-voltage equipment (instrument transformers, arresters, surge suppressors, etc.) when designing and improving individual design solutions. The calculation results are in good agreement with the data of experimental studies and statistical information obtained as a result of monitoring the operation of insulating structures, taking into account real operating conditions and the impact of external factors. The implementation of this technique makes it possible to take into account the influence of external factors and operational characteristics inherent in instrument transformers and surge arresters. In the proposed method, as an example, a supporting insulating cover is considered, which is during operation in the most unfavorable conditions, such as external pollution, moisture and their combination, overvoltage of various origins, etc. Theoretical conclusions are confirmed by the results of calculations on the example of the most mass-produced design of a gas-filled current transformer TOG-245 series. A more accurate determination of the effectiveness of the proposed method for predicting the parameters of the distribution of the field strength under the action of the shielding system can be achieved by carrying out an additional series of calculations and experimental tests of specific insulating structures. Thus, it was concluded that the obtained results can be used to assess the external insulation performance of both gas-filled instrument transformers and similar high-voltage switchgear equipment and transformer substations.

A System to Ensure Safety while Switching High Voltage Switchgears

A System to Ensure Safety while Switching High Voltage Switchgears

Real-Time Monitoring of High Voltage Switch Based on CAD

In the process of online real-time monitoring of intelligent digital filter high-voltage switchgear, the mechanical state diagnosis of high-voltage circuit breaker is based on fully understanding the mechanical characteristics of each component of circuit breaker. In this paper, K-means clustering algorithm is applied to the mechanical state detection of digital filter high-voltage switchgear. The mechanical state of the digital filter high-voltage switchgear is monitored in real time by using 126 kV GIS. Through fault simulation experiment and mechanical stability experiment, the corresponding changes of characteristics of each mechanical component of circuit breaker in signal waveform and corresponding data changes are found. The experimental results show that this method has good running speed and stability and is more suitable for the real-time monitoring of intelligent digital filter high-voltage switchgear.

Detection and Location of High Voltage Power Switchgear Operating Equipment based on Iterative Segmentation

During the operation of high voltage switchgear in substation, partial discharge may occur. Therefore, it is necessary to develop automatic operation equipment to reduce personnel risk. For this reason, this paper proposes a detection method of key operation control components based on segmentation zone iterative detection for the operation environment of high-voltage switchgear in substation, which is used to provide basic operation guidance for the operation robot of high-voltage switchgear. This method can quickly analyze the switchgear image and find out the operable parts. At the same time, through the extraction of topological relationship and image features, the feature relation network of the operating parts is constructed. On this basis, the semantic extraction of the operating parts based on feature matching is realized, which lays the foundation for the realization of automatic mechanical operation. The method proposed in this paper is tested on the actual switch cabinet data, and the results show that the actual detection accuracy is significantly improved compared with the existing methods, and has good scalability and adaptability.

Research on Intelligent Manufacturing of High and Low Voltage Switchgear

Research on Intelligent Manufacturing of High and Low Voltage Switchgear

Analysis on the Current Situation of Electrical Design of High and Low Voltage Switchgear Sets and Analysis on the Development Direction of Intelligentization

Analysis on the Current Situation of Electrical Design of High and Low Voltage Switchgear Sets and Analysis on the Development Direction of Intelligentization

Numerical simulation of the condensation process in high voltage switchgear based on the temperature and humidity distribution

The condensation on solid materials surface inside switchgear is an important reason threatening its safety and reliability. The formation of condensation is closely related to the temperature and humidity distribution inside the switchgear. A 3-D simplified finite element calculation model for the switchgear is established, including the bus bar, the wall bushing, the circuit breaker, the cables and other key components. Based on the electromagnetic-temperature-humidity multi-physical field coupling method, the temperature distribution inside the switchgear are calculated when the operating current flows through the bus-bar. Furthermore, the humidity diffusion process is also calculated when the relative humidity of external environment was 0.8, and the relative humidity inside the switchgear is obtained. The calculation results show that the surface humidity of the contact box of the circuit breaker is the highest whereas the temperature is the lowest, which is the location where the condensation is easy to occur.

Design of Automatic Temperature Control System for High and Low Voltage Switchgear

Design of Automatic Temperature Control System for High and Low Voltage Switchgear

Optimization on airflow distribution for anti-condensation of high-voltage switchgear using CFD method

High-voltage switchgear is indispensable for power system. Condensation of the switchgear occurs frequently due to water vapor infiltration and water accumulation in cable trench, which may cause large-scale blackout of the power system. Effective dehumidification measures are crucial to safe and stable operation of the switchgear. In this paper, an air-conditioning based dry-air dehumidification measure is proposed for anti-condensation of the switchgear. Different airflow distributions are studied by numerical simulation of the thermal-humidity environment within the switchgear. Results show that the performance of the proposed dehumidification system is satisfactory. The switchgear wall temperature can be up to 7.6 °C higher than the return air dew point temperature, and the moisture content differences between the supply and return air can be more than 3.4 g/kg. Besides, some optimization measures for improving the dehumidification effect are proposed. After the optimization of the airflow distribution, the relative humidity and the temperature of the return air are reduced by 3.3% and 1.3 °C, respectively.

Problems of Remote Temperature Measurement of Small Objects of Electricity Power Systems—On the Example of Lashing Clamps of Bridge Connections on High Voltage Poles

The article presents problems occurring during remote temperature measurement of lashing clamps of bridge connections on high voltage poles using thermal imaging cameras. The basic metrological parameters of thermal imaging cameras are described. On this basis, typical errors made during the inspection of high voltage lines supplying power substations are presented using infrared cameras. Researching the possible solutions for the problems of remote temperature measurement of small objects of electricity power systems—on the example of lashing clamps of bridge connections on high voltage poles in the proposed paper and showing the basic metrological aspects and parameters of thermal imaging cameras are important because, in this way, it is observed to eliminate costly interruptions in the supply of electricity associated with the breaking of power lines. Small objects are quite difficult to be controlled and monitored on large grids and on large powerline poles; thus, it is very challenging to interpret the data offered by thermograms. The problem of remote temperature measurement of small objects in electrical power engineering is very important from the point of view of the quality and reliability of electricity supply. Obtaining early warning information about the occurrence of overheating, e.g., on lashing clamps of bridge connections, is very important, as it eliminates costly interruptions in the supply of electricity associated with the breaking of power lines supplying high voltage switchgears or substations.

Research of Emergency Modes of Wind Power Plants Using Computer Simulation

The aim of this study is to investigate changes in the wind power plant energy production parameters under the conditions of sudden wind changes and voltage drop. To achieve these goals, a simulation of operation of wind power plants was performed. Twelve wind turbines with variable rotational speed equipped with a Fuhrländer FL 2500/104 asynchronous double-fed induction generator (DFIG) were used, each with an installed capacity of 2.5 MW. A general scheme of a wind power plant has been developed using a modular-trunk power distribution scheme. The system consists of wind power modules and a central substation, which allows total power to be supplied to the power system at a voltage of 35 kV. The central substation uses two high voltage switchgears. Four modules were used, each of them consisting of three wind turbines, with a power of 7.5 MW. The simulation of the wind turbines was performed in the MATLAB® Simulink® software environment. The mode of response of the turbines to a change in wind speed, a voltage drop in the 35 kV voltage system, and a one-phase short circuit to the ground in the system of 10.5 kV voltage was explored. The results show that a sudden voltage drop and the appearance of short circuits influence the wind power plant (WPP) operation in a different way independent of regulation mode. The power generation from WPP will be limited when voltage drop occurred for both AC and Voltage regulation mode and during short circuits while WPP is set on AC regulation mode.

Research on modularizing design of 10 kV switchgear with line outlet for live maintenance

In order to improve the reliability and safety of power supply and reduce the failure rate of switchgear, this paper designs a novel high-voltage switchgear which is reliable and safe. A simulation model for electric field and temperature field simulation is established to check the insulation and temperature rise performance of the new designing switchgear. The electric field simulation results show that the place where there has connection or corner has strong chance to occur partial discharge. The heat field results reveal that even in the condition of passing through current with long operation time, the maximum temperature rise of the switchgear is 55.9 K and 48.7 K respectively, which is lower than the standard design requirement 70 K. Some measures can be taken to improve the insulation and temperature rise performance of the new switchgear, such as polishing the connection or using stainless steel at the top of the switchgear.

Design of an Intelligent Fiber Bragg Grating Temperature Measurement System for Electrical Equipment

For the power system, the main reason for many fire accidents is that the temperature of electrical equipment is too high, and now the widely used fire detector can only detect the fire that has occurred. If the temperature change of electrical equipment can be tracked in real time and the alarm information can be sent in time when the operating temperature is too high, the fire of power system can be scientifically and effectively prevented. The use of fiber Bragg grating sensor can provide a basis for the realization of the theoretical conception. For the traditional temperature measurement system, fiber Bragg grating temperature measurement system has the advantages of convenient maintenance, fault detection, less affected by light source power fluctuation, information sharing and long service time. It can effectively measure the temperature of isolated contact of high-voltage switchgear, the temperature of wet steam inside steam turbine and the surface temperature of power cable, etc. This paper researches a design of fiber Bragg grating temperature measurement system.

Evaluation and optimization of electric field on a high-voltage switchgear in nuclear power station

Safety of electric power systems depends heavily on distribution of electric field in high-voltage switchgear. Switchgear failure can lead to fatal disasters in important systems. It is necessary to evaluate electric field and insulation performance for high-voltage switchgear in key systems. In this paper, considering a high-voltage switchgear system designed for nuclear power station, a three-dimensional finite element model is developed for the whole system. Distribution of electric field is simulated under different loads, including the specified voltage and the overload. The insulation property of the switchgear system is then evaluated. Experiment on the physical prototype validates the simulation evaluation. To make the electrical field well distributed and reduce peak value, method of orthogonal experiment is used for parameter design. Optimization and improvement are then proposed. The optimization results show that the reliability is improved and the electric field is well distributed. The numerical model is established on personal computer, while it is solved remotely on High Performance Computing Center. Corresponding modeling techniques and computing methods are provided in this paper.

Effects of Different Post-Treatments on Arc Erosion Resistance of Cold-Sprayed AgC Composite Electric Contact

Graphite-silver (AgC) composite materials are widely used in outdoor high-voltage electrical switchgear due to their combining properties of excellent conductivity and outstanding arc-suppressing performance. However, the methods for fabricating AgC composite materials still have some limitations. In this study, the cold spray technique was adopted to deposit AgC composite coatings with the optimized parameters on the copper substrate. Then, AgC coatings were annealed in the furnace and treated by laser scanning, respectively, to further improve the arc erosion resistance performance of the coatings. The results show that the phase structure and electrical resistance of AgC coatings were not influenced by the post-treatment process. Furthermore, excellent hydrophobic performance was obtained after surface laser scanning treatment. The laser scanning treatment exhibited favorable advantages in enhancing the arc erosion resistance of AgC coatings, which indicated the lowest arc erosion rate compared with the cold-sprayed and annealed coatings.

Technological Aspects of the Use of Cast Polymer Insulation for High-Voltage Switchgear and Busbars

Technological Aspects of the Use of Cast Polymer Insulation for High-Voltage Switchgear and Busbars

Exploration of Ni-doped BN monolayer as a promising gas sensor for air decomposed species in the high-voltage switchgears

In this work, we propose Ni-doped h-BN (Ni-BN) monolayer as a promising gas sensor for NOx (x = 1–2) detection based on first-principles theory, in order to evaluate the operation status of the high-voltage switchgear. The Ni dopant prefers to be trapped on the TN site of the h-BN monolayer with binding force (Eb) of −1.26 eV. Upon NOx adsorption, chemisorption is identified given the large adsorption energy (Ead) of −2.94 and −2.71 eV in NO and NO2 systems, respectively. Besides, the electronic behavior of the Ni-BN monolayer undergoes remarkable deformations after adsorption of NO and NO2, which widens its bandgap by 0.266 and 0.545 eV from that of 1.129 eV, respectively. This ensures the detectable electrical response of Ni-BN monolayer as a resistance-type gas sensor for NOx detection. Besides, the desirable changes in the work function of Ni-BN monolayer makes it possible to be applied in field-effect transistor for NOx sensing. Our work means to suggest novel sensing material for NOx detection, and we are hopeful that Ni-BN monolayer is full of potential to be one of the promising NOx sensors to be applied in many fields.