# Performance Analysis of Quantum Key Distribution Technology for Power Business
## 3 Performance Characteristics of Power QKD System
### Performance Index Analysis  
Compared with the QKD network of other industries, the power communication network coexists with the power transmission network, which has the characteristics of wide geographical area, diverse line environment and complex network structure. Since power communication network is composed of overhead optical fiber and BOFC, the traditional QKD system is easily affected by the external wind, rain, snow and other environment factors, resulting in low generation efficiency of quantum cryptography. To evaluate the practical performance of power QKD system more effectively, this article proposes the evaluation index from the key tier and the business layer for the situations that may occur in the actual link, as shown in Figure 2. The key tier evaluation index is reflected in the factors that affect the secret key rate in the quantum channel. The business layer evaluation indicators focus on the transmission performance of the system when quantum virtual private network (QVPN) is used for encrypted transmission. In order to test the performance of QKD device and QVPN in different environments, we simulated different test environments.  
Case 1: The Key Tier  
(1) Distance loss test: by setting up fiber optic environments with different transmission distances, test the secret key rate of QKD devices under different distance attenuation conditions, and record the coding curve within one hour after stable coding. The actual line is BOFC (16.58 km). The simulated environment consists of four bare fibers with lengths of 10 km, 20 km, 30 km and 40 km.  
(2) Galloping loss test: on the basis of distance test, the galloping simulation test environment of optical fiber composite overhead ground wire (OPGW) is established. Test the secret key rate of the  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**QKD** & \multicolumn{8}{c}{**Examples of QKD**} \\ \hline [PERSON]’s bit sequence & 0 & 1 & 0 & 0 & 1 & 1 & 0 & 1 \\ [PERSON]’s basis & + & + & \(\times\) & \(\times\) & + & + & \(\times\) & \(\times\) \\ [PERSON]’s polarization & \(\uparrow\) & \(\rightarrow\) & \(\
earrow\) & \(\rightarrow\) & \(\
earrow\) & \(\searrow\) \\ [PERSON]’s basis & \(\times\) & + & \(\times\) & + & \(\times\) & + & + & \(\times\) \\ [PERSON]’s measurement & \(\
earrow\) or \(\searrow\) & \(\rightarrow\) & \(\
earrow\) & \(\uparrow\) or \(\rightarrow\) & \(\
earrow\) or \(\searrow\) & \(\rightarrow\) & \(\uparrow\) or \(\rightarrow\) & \(\searrow\) \\ Shared sifted key & - & 1 & 0 & - & - & 1 & - & 1 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Quantum key generation based on the BB84 Protocol.  
Figure 1: Quantum key distribution (QKD) based on polarization encoding.  
quantum device under different wind conditions within the transmission distance, and statistically determine the code curve within one hour after the code is stable. Wind level: calm, light air, light breeze, gentle breeze and moderate breeze (Table 2).  
(3) Splice loss test: in a fixed transmission distance, by inserting splice fibers with different losses, test the effect of fiber environment on the secret key rate of the quantum device under different splice losses. In this experiment, three different spliced optical fibers were used to test the analog lines.  
Case 2: The Business Tier  
(1) Data traffic test: by loading a network performance tester at both ends of the service, test the transmission performance parameters such as network delay, jitter, throughput and packet loss rate when the classic channel uses QVPN encrypted transmission.  
(2) Encryption algorithm test: a network performance tester is used to test transport performance when QVPN uses different encryption algorithms to encrypt business data. QVPN supports three encryption methods, such as Internet key exchange (IKE), SM4/AES + quantum key.  
(3) System stability test: by connecting the actual loop fiber-optic line, test the secret key rate of the quantum device in the actual transmission environment within \(7\times 24\) h.