Switching Operations in 110 kV Networks in the Context of Synchro-Check and Mitigation of Switching Stress by Utilizing Proper Control of Renewables and Energy Storages

Abstract

Synchro-check (SC) relays are devices that control synchronization between different fragments of power system networks. Synchronism is monitored by controlling the voltage amplitude, angle, and frequency differences. The goal of monitoring is to avoid dangerous transients after the circuit breaker (CB) closing, which occur when the differences between the voltage, angle, and frequency at both sides of the CB are above the threshold. Although the idea of SC is straightforward, one needs to realize that blocking of the CB closing may cause even more severe issues, i.e., the deterioration of power system stability and safety. The conflicting goals of the switching operation result in many different interpretations, regarding the recommended settings and utilization of the SC relays in different locations of power system networks. The paper presents considerations connected with switching operations in power systems, in particular, in 110 kV networks. Different problems connected with switching operations are highlighted and described. Moreover, the switching-relevant parameters and switching constraints are provided. Further, the simulation results connected with switching operations are presented, the realistic possible voltage and angle differences before switching operations are provided, and the impacts of mitigation measures—renewables and energy storage—are estimated. Finally, the proposed procedures and algorithms of switching stress mitigation are provided.

Keywords

• energy storage
• switching operation
• synchro-check
• synchronism
• renewable
• PV plant