Zero-Energy Sag Corrector With Reduced Device Count

Voltage sags are the leading cause of unscheduled downtime in industrial plants with high levels of automation. Zero-energy sag correctors (ZESCs) that utilize energy from those phases that have sufficient remaining voltage on them promise levels of protection that are comparable with conventional energy storage based sag correctors, but in a more compact package. This paper presents a ZESC topology with reduced device count using readily available device packages that can realize similar performance as the original ZESC circuit. The proposed ZESC behaves like a ldquothin AC converter,rdquo and can be integrated with existing assets such as transformers and switchgears. This paper presents details of the operation, design, and experimental results for such a ZESC circuit.