# Performance Analysis of Quantum Key Distribution Technology for Power Business
## 5 Experimental Results
The plant station G sends remote control and remote adjustment instructions through the RTU, analyzes the messages received by the RTU and performs consistency comparison with the messages sent by the mobile master station (substation). This experiment applied QKD to remote signaling, telemetry, remote control and remote adjustment services. Experimental results show that QKD-based dispatching automation obtains the consistency of four business interaction information between plant station G and master station A. Meanwhile, the dispatching automation system works normally according to the received instructions, and the transmission delay was less than 3 ms, which meets the indicators of stable operation of power control businesses. Relying on the test environment, this experiment verified the performance of the fast polarization feedback algorithm. Under the condition that the mean value of line polarization change rate was less than 6.27 rad/s, the average time for the single quantum state correction of QKD equipment based on fast polarization feedback technology was less than 6.95 ms (test time period: 10 min). In the experiment, a standard single-mode fiber (G652, loss: 15 dB) with a length of 65.7 km was used to test the key rate of the QKD system. The average secret key rate was about 3.8 Kbps. Figure 11: The actual line of dispatching automation test. Considering that the video conference was affected by multiple factors, such as the environment, lines and equipment, this paper implements a multi-relay hybrid networking application in the video conference in the power industry. As shown in Figure 9, the demonstration project spans three substations and two-segment overhead optical cables of a multi-relay power QKD network, solving the technical problem of stable quantum key coding in a complex power communication network environment. At the same time, we applied QKD to satellite emergency communication systems, to achieve the security of wireless data transmission. Quantum fast polarization feedback technology was used to overcome the influence of the line environment on the quantum key coding. A correction model was built by quickly detecting changes in the quantum polarization state in an overhead power cable. The correction of abnormal changes was completed, which effectively improved the adaptability of QKD technology in complex power network environments. Based on the fast polarization feedback technology, the actual average effective coding time of the quantum channel was increased from 68.51% of ordinary devices to 99.76%, and the actual daily average effective secret key rate was increased from 63.41% of ordinary devices to 83.51%. As shown in Figure 11, in this QKD-based disaster recovery service test, the actual line between the main station A and the substation C was selected to set up a verification environment for QVPN encrypted transmission. The main station A and the substation C are the clients and servers of the disaster recovery service test, respectively. By using the FTP data download method, the QKD secret key rate and QVPN transmission performance were tested. When the line attenuation of the verification environment was 13 dB, the average secret key rate of the quantum key can reach 27.79 Kbps. When the service packet length was greater than 1024 bytes, the QVPN transmission rate was 581 Mbit/s (the time delay was less than 8 ms) and the database backup comparison was consistent, which meets the transmission requirements of power disaster recovery services. At the same time, this experiment set up a QKD-based distribution automation and power information collection service test environment, in which the bandwidth was 2 Mbit/s, the encryption algorithm was SM4 and the update frequency of the quantum key was 16 times/s. The test results show that the delays of the proposed scheme are 3.67 ms and 3.68 ms, respectively, which meets the delay standard requirements of service operation and the accuracy requirements of data transmission.