As the world's largest producer and consumer of electricity, China has deployed a project to transport energy resources from West China to East China through extra-high-voltage transmission lines to reduce carbon emissions. In the Loess Plateau, the safety of transmission lines has been frequently threatened by natural hazards such as landslides and ground subsidence. However, it is prohibitively expensive to build a monitoring network covering all transmission lines to provide timely early warnings, particularly for sparsely inhabited areas. Based on the large-scale coverage of Sentinel-1 SLC images in IW TOPS mode, we utilized persistent scatterer interferometry to measure the ground target movements along transmission lines with millimeter accuracy. Three regions of interest were selected to reflect the different environmental conditions from the south to north of the Yan'an Region. The displacement variations were compared and evaluated at three spatial scales (region, route, local) from October 2018 to November 2019. On the regional scale, the deformation variation decreased from the south (-36 - 29 mm/yr) to the north (-19 - 20 mm/yr), which was significantly different as determined by the analysis of variance (ANOVA) and can be attributed to the impacts of water-induced subsidence and human activities. On the local scale, the results showed that the deformation rate was less than 10 mm/yr, which suggested a stable status for the experimental line sections. The displacement time series of transmission towers preliminarily revealed seasonal displacement variations, wherein winter and spring were relatively quiet periods. The application of advanced InSAR technologies has excellent prospects in smart grid implementation.