Optimization of the protection measures for stray alternating current interference

• A multi-section spacing optimization method for zinc ribbon was established. • Application of simulated annealing algorithm. • The maximum discharge rate of zinc ribbon bed is the objective function. • Numerical simulation is combined with fitted equations. • Comparison of optimization results of different segments. Both alternating current (AC) electrified railways and power transmission lines may result in stray current interference in nearby buried pipelines, which may lead to a risk of corrosion in these pipelines. Zinc ribbon current drainage is an effective method for protecting against stray current interference. However, only few studies have focused on the selection of zinc ribbon spacing in horizontally distributed zinc ribbons. This study examined the protective effect of discharge flow in zinc ribbons. An optimization technique was developed for the protection measures of stray AC interference. In this technique, the discharge flow of a zinc ribbon was used as the objective function, and the spacing between each zinc ribbon was used as a variable. Stray current protection measures were optimized by maximizing the discharge flow of the zinc ribbons. In addition, a ground bed resistance fitting equation and a pipeline interference voltage equation were obtained using numerical simulation techniques. Ground bed spacing was optimized using a simulated annealing algorithm. With an AC electrified railroad in Guangzhou taken as an example, this optimization measure was applied to the normal operation of a pipeline to determine the optimal spacing of the zinc ribbons at each key point. The results indicated that after the optimization of zinc ribbon drainage, the number and length of the zinc ribbons substantially decreased, and the AC interference voltage decreased with more favorable drainage. In summary, the proposed optimization measure offers improved protective effects, facilitates the selection of zinc ribbon spacing, and reduces the number of zinc ribbons required.