The synthesis of digital twin (DT) technology into smart grid systems has emerged as a promising approach for enhancing operational efficiency, reliability, and resilience in en-ergy management. DTs offer a virtual representation of physical assets and processes, enabling real-time monitoring, predictive analytics, optimization, and control. This survey paper provides an overview of the recent advances in designing DTs to upgrade the smart grid. We mainly focus on aspects of DT concept, DT empowered economic dispatch, DT empowered prediction and diagnosis, and DT empowered frequency and voltage regulations. Finally, we pinpoint potential challenges and conclude this paper.