Search

By studying the forging and heat treatment processes of CrMo alloy structural steel OPGW fittings under extreme cold conditions, comparing the process performance of several treatment schemes, the heat treatment and forging process schemes of forging products with extreme cold resistance OPGW fittings are determined. As part of the communication solution, this research has ensured the application of OPGW in extremely cold regions.

In order to improve electrical matching between ethylene-propylene-diene misch-polymere (EPDM) reinforce insulation and crosslinked polyethylene (XLPE) main insulation in direct current (DC) cable accessories, the glyceryl monooleate (GMO) organic compound composed of several polar-groups and one long carbon chain is employed for chemical graft modification on EPDM to ameliorate DC electrical performances. Charge trap characteristics are analyzed by testing thermal stimulation current (TSC) and verified by calculating first-principles electronic properties to elucidate the GMO-graft-modified charge trapping mechanism accounting for DC electric conductance and dielectric breakdown. The grafted GMO molecules introduce substantial shallow charge traps that lead to nonlinear profiles of electric conduction versus electric field and cause hopping transports of percolation conductance. Electric conductance of EPDM is significantly improved by GMO graft for electrical matching with XLPE, while a high level of dielectric breakdown strength is retained sufficiently for reinforce insulation in cable accessories. Shallow charge traps introduced by GMO graft are capable of capturing charge carriers to form homocharge layers near electrodes which can scatter the transporting charge carriers and exclude further charge injections, thus to mitigate the dielectric breakdown strength reduction caused by electric conductivity improvement. Electric field finite-element simulations demonstrate that the electric field in DC cable terminals can be evidently homogenized by using GMO-grafted EPDM as reinforce insulation. Published version

Storage battery is an indispensable energy storage device at present. It is widely applied to industries like electric automobiles due to its advantages such as safety, reliability, low cost, etc. However, like most storage batteries, lead-acid battery has a series of problems in the low temperature environment such as the plunge of capacity, difficulty of charge, and so on, which deeply influence its application effect. To improve the low temperature performance of lead-acid battery, carbon materials could be added to the cathode of lead-acid battery. By measuring the properties like HRPSoC cycle and dynamic charging under different carbon (graphite) content, this article concludes that the addition of carbon material could improve the low-temperature performance of lead-acid battery. When the carbon content is between 0.3% and 0.9%, the improvement effect is relatively better. The research result of this article has a reference function to the design and development of low-temperature lead-acid batteries.

As the important device to perceive the operating state of grid, the condition monitoring device of electric equipment solves such problems as the high rate of false alarm and failure of device caused by the low temperature in winter of cold areas. This paper measures the thermal conductivity of such three kinds of materials as asbestos, rubber and nano porous aerogels in the temperature range of -55°C to +80°C by steady state method, and analyzes the influence of temperature on the thermal conductivity of three materials. According to the result of experiment, the thermal conductivity of nano porous aerogels is the lowest and is affected least by temperature among three kinds of materials. Nano porous aerogels apply to state monitoring device operated in cold areas; and rubber can also be used as thermal insulation material when the operating temperature is generally higher than -20°C.

Epoxy resin insulating materials have been extensively applied to main power transmission and transformation equipment. As the use environment of power transmission and transformation equipment becomes increasingly harsh, the reliability requirement of power grids for equipment is becoming higher and higher. It’s very necessary to master electrical and mechanical properties of low-temperature epoxy resin insulating materials. Dielectric properties, power-frequency breakdown properties, power-frequency flashover properties and mechanical properties of epoxy resin insulating materials under low temperature were investigated in this paper. The study results indicate that as the temperature declines, dielectric properties of epoxy resin composite materials are slightly degraded. After the temperature drops to below -40°C, dielectric properties start being gradually recovered to the state under normal temperature; AC breakdown, AC flashover and tensile properties of the materials are gradually improved as the temperature decreases.

This paper discusses the application of wireless sensor network in the smart grid and information security requirements, such as confidentiality, integrity, availability, and data freshness. We also analyze the physical attack and several typical network attacks of WSNs in smart grid. We elaborate the implementation process, characteristics and the hazards to the power grid of these attacks. In the paper, we propose a communications security policy of WSNs in smart grid and corresponding information security technologies, we analyze the characteristics and existing solutions of such information security technology, then we propose corresponding solutions of security technology applicable to smart grid. In the end, we summarize some issues in the realization of WSNs security technologies in smart grid and discuss the latest trends.