Research of thermal endurance of cables of secondary systems of TsGPP substation under short-circuit conditions

The article presents the results of research on thermal endurance of control cables of secondary systems of substation 500 kV “TsGPP” substation under single-phase short circuits (SC). The study is based on the combination of field experiments and numerical modeling of the computational model of the grounding, which determines the distribution of potentials on the grounding and currents on the cable shields. The results showed that when a short-circuit occurs on the OS (Outdoor Switchgear)-220 kV and OS-110 kV current density flowing through the screen may exceed the permissible values, which leads to thermal damage to cables and, as a result, an increased risk of damage to the secondary relay protection and control systems. Based on the analysis of the obtained data, recommendations for optimizing the configuration of the grounding have been proposed. Densification of local grounding and an increase in the number of connections between the shield grounding and the grounding grid leads to a reduction in the potential distribution gradient in the grounding circuit of the “TsGPP” substation. Given the soil resistivity parameters specific to the substation under study, the current levels flowing through the control cable screens have been reduced to values below the established permissible thresholds. For the first time, the results of research conducted at an actual high-voltage substation have demonstrated the feasibility of ensuring the thermal stability of control cables through the reconstruction of the grounding.