With the rapid development of information and communication technology, traditional power grids have gradually transformed into smart grids. As a new type of smart network optimized for power services, smart grids have changed the cumbersome traditional power service model, constructing a flexible and efficient communication network that can provide users with two-way interactive power services. However, the two-way communication services of smart grids also face challenges such as information tampering, leakage, and high communication overhead. During data transmission, malicious entities may pose threats to the balance of power supply and demand and users’ privacy through attacks such as identity forgery. Therefore, the smart grid communication network should employ identity authentication and privacy protection mechanisms while controlling communication overhead and computational costs. This paper studies the trend of changes in the electrical architecture of smart grids, abstracts a model that fits modern smart grids from the existing functional domain division modes of power grids, and examines node authentication and key exchange protocols in smart grids, proposing a lightweight security authentication scheme for smart grids.