In order to explore a better way of secure communication mode for the signal transmission between substations

a solution for combining quantum key distribution(QKD)with one-time pad(OTD)in practical engineering application is proposed. The plaintext

ciphertext and key are unified as standard E1 interface signal

which meet the real OTD system requirements. The polarization state encoding based QKD using decoy state protocol can adjust the rate of QKD according to the quality of the fiber-optic channel by the choice of compression ratio 1 or 128 or 1 024

and supports the Chinese and international standards of commercial cipher encryption algorithm. Simulations show that

compared with the performance of the classic key distribution system

the proposed solution has advantages in terms of confidentiality

integrity and identifiability

and is unique in privacy amplification. This work is supported by State Grid Corporation of China(No. SGZJ0000BGJS1600324).