During the reconstruction or expansion of power plants and substations, copper and steel ground grids are often connected, and the resulting galvanic corrosion shortens the service life of steel ground grids. However, no method is yet available for calculating the galvanic corrosion rate of the entire ground grid. On the basis of electrochemical theory, method of moments, and Taylor's formula, a method is proposed for calculating the galvanic corrosion rate of connected ground grids composed of dissimilar metals, and the effectiveness of this method is verified through galvanic corrosion experiments and FEM. For an actual project in which copper and steel ground grids are connected, the galvanic corrosion rate distribution of ground grids is calculated and analysed. According to the results, galvanic corrosion can significantly reduce the service life of ground grids, and in this engineering case, the remaining service life of the steel ground grid is reduced from 17.4 to 9.7 years (a decrease of 44.3%). The galvanic corrosion rates at the edges and corners of steel ground grid are considerably higher than those in its interior, and the galvanic corrosion rate of the steel ground electrodes is highest near the copper ground grid.

为分析大区域电网对埋地油气管道的持续干扰,本研究在分析持续干扰电压幅值随线路和管道间距变化规律的基础上,提出利用阈值确定大区域电网建模边界,以构建电网对管道持续干扰分析模型的方法,并建立了计算截断误差的概率模型.结果表明:由距离管道较远线路产生的小幅值干扰电压分量的向量和近似为零,且这些干扰电压分量向量和的模值近似服从瑞利分布;在分析线路平均间距大于200 m的220 kV电网对管道的持续干扰时,仅考虑管道两侧4.20 km内导线按ZB型杆塔排列的线路,4.10 km内导线按ZM型杆塔排列的线路,10.65 km内导线按SZ型杆塔排列的线路,11.93 km内导线按SSZ型杆塔排列的线路,11.84 km内导线按SSSZ型杆塔排列的线路,即可使截断误差有95％的概率小于2.23 V.

雷击输电杆塔时,通过接地装置流入大地电流和流过地线的电流都会在附近埋地管道的防腐层上形成干扰电压,对管道形成威胁.本研究利用频域矩量法结合时频转化的方法,建立了雷击输电杆塔时附近埋地管道防腐层电压的计算模型,给出了土壤电阻率、管道与输电线路的间距、管道尺寸、防腐层电阻率和防腐层厚度对防腐层电压的影响,并对安装排流带和改变杆塔接地装置结构的防护措施的效果进行了计算,结果表明合理的布置排流带和改变接地装置结构,可降低管道防腐层的电压.

The impulse performance of grounding electrodes highly depends on soil impulse discharge characteristics. The analysis of soil discharge dynamic process images is helpful to understand the impulse discharge mechanism of grounding electrodes. This paper designed an optical-electrical synchronous observation platform for simulate soil (SiO2 crystal) discharge, and discharge dynamic process images is obtained by high-speed camera. Through analysing breakdown delay time and thermal power before breakdown, it is found that soil impulse discharge is mainly an electrical breakdown process, and soil ionization intensity is positively correlated with the light intensity emitted by whole soil sample in breakdown channel development stage. The time from voltage application to the occurrence of ionization is defined as initial ionization delay time (IIDT). Using image processing technology, the change curve of optical image average grayscale value with time in the process of soil discharge is obtained, and a calculation method of IIDT is proposed by comparing the difference between average grayscale value curve and background image average grayscale value. Experiment results show that IIDT is negatively correlated with impulse voltage, particle size and water content, but not with salt content.

为了掌握加装均流电阻对直流接地极运行性能的影响，为均流电阻装置的应用及运维提供参考，以水平圆环接地极为对象，分析了接地极加装均流电阻后的电气性能和温升性能变化，以及均流电阻阻值偏移对接地极电流分布和跨步电压的影响。结果表明：加装均流电阻可以使电流在各环段上的分配更均衡，相应的各极环附近最大跨步电压和温升更均衡，从而减小接地极的最大跨步电压和最大温升。均流电阻阻值偏移量越大，极环电流和最大跨步电压的变化量越大；当各极环均流电阻阻值的偏移量不均衡时，极环电流和最大跨步电压的变化量会进一步增加。若要将最大跨步电压的变化控制在10%内，均流电阻阻值的偏移量不宜超过5%。