Abstract: With the advancement of smart grid construction, remote capacity verification of series-connected batteries in substation DC systems has become a key direction for the digital transformation of operation and maintenance. However, the multi-system interaction process faces potential security risks such as communication latency, data leakage, and device authentication vulnerabilities. To address these issues, combined with the current development status of the power Internet of Things technology, this paper proposes a remote capacity verification communication technology and security strategy based on the wireless LAN authentication and privacy infrastructure (WAPI) and improved elliptic curve cryptography (ECC).The proposed scheme is designed with an IoT architecture integrating novel wireless sensors and edge gateways. It strengthens link security by optimizing the WAPI identity authentication process, and improves the ECC algorithm by introducing timestamps to dynamically generate public keys, so as to meet the requirements of multidimensional data encryption. The Dolev-Yao threat model is adopted to evaluate the security, and both formal and informal analyses prove that the scheme can effectively resist various types of attacks.Experimental results show that the optimized WAPI + improved ECC scheme proposed in this paper only accounts for 60.1%, 33.0% and 17.2% of the traditional WAPI + traditional ECC scheme in three core overhead dimensions, namely computing, communication and storage overhead. Compared with the traditional WAPI + RSA public-key encryption algorithm scheme, the overheads of the proposed scheme are 44.9%, 44.8% and 62.5% respectively. These results fully demonstrate the high efficiency and lightweight advantages of the proposed scheme in edge computing scenarios.