A power system comprises five major segments as follows: generation

transmission

transformation

distribution

and consumption

involving a wide variety and large quantity of equipment. Intelligent operation and maintenance (IOM) is therefore essential to ensuring the system’s safe and stable operation. As an emerging technology

digital twin can provide strong supports for IOM of power equipment. This paper first analyzes the business requirements of IOM and reviews the relevant concepts

characteristics

and application framework of digital twins. Then

this paper systematically reviews the research status of six key technologies

including multi-dimensional sensing of equipment operating states

real-time data transmission and cyber-physical interaction

twin data storage and preprocessing

twin model construction and lightweighting

digital twin-driven IOM services

and digital-twin maturity assessment. On this basis

a refined application architecture and a maturity assessment system are proposed. Finally

by taking gas insulated switchgear (GIS) operation and maintenance as a case study

the proposed framework is validated

and the major challenges and future research directions of digital twins for IOM of power equipment are systematically summarized.