Impacts of Voltage Sags and Protection Coordination on Sensitive Equipment in Distribution Systems

Abstract

Nowadays, a lot of sensitive electronic equipment is widely used in modern power systems such as power converters and adjustable speed drivers. Voltage sags have gained more interest due to their consequences on the performance of sensitive equipment (SE). Malfunction or failure of the equipment that leads to work or production losses can be caused by voltage sags. As a result, it is essential to have information on equipment sensitivity. If the magnitude and duration of voltage sag exceed the equipment sensitivity threshold, the equipment can malfunction, and such a consequence can affect an entire automatic process, resulting in high economical losses. Reclosers and fuses are the main overcurrent protection devices in distribution systems. Poor coordination may adversely impact on the sensitive equipment. This paper presents a method to analyze impacts of voltage sags and protection coordination on sensitive equipment. A fault position method and mathematical equations describing characteristics of protection devices are used to calculate voltage sags and the protection settings. Voltage tolerance thresholds and protective device characteristics are used to analyze protection and sensitive equipment coordination. Based on the results, new settings for protective devices can be adjusted for sensitive equipment in distribution systems. The Roy Billinton Test System (RBTS) bus 2 is used to analyze impacts of voltage sags and protection coordination.