# Random Violation Risk Degree Based Service Channel Routing Mechanism in Smart Grid
## 2 Related Work
Papers [22; 23] defined the concept of availability border and proposed the path availability evaluation method and the routing algorithm on the assumption that failure arrival rate was dynamic and corresponding repair time was fixed. Paper [24] replaced the statistical availability with service continuity and proposed the probability Equation of service uninterrupted, which effectively promoted the actual availability of the service. By statistical methods, paper [25] obtained the accurate probability of service channel failure time exceeding the specified time according to a lot of simulation based a given network environment. But when the network environment changed, the simulation needed to be restarted which reduced the universality of this method. The above methods mentioned are considering the actual availability which is more accurate than \(A_{SPA}\) in routing. However, because the time to repair (\(TTR\)) of channel is changing with the environment and the geographical location, thus the assumption of a fixed \(TTR\) will limit the application scope of the above methods. On the other aspect, if the correlation among \(TTR\)s of different channels is not considered when selecting the primary and backup routing, the risk of primary and backup channels simultaneously being in failure will be increasing. Therefore, random \(TTR\) and its impact should be further considered for universal service channel failure risk routing mechanism. Further studies showed that the occurrence of an electric power communication failure event and the fluctuations of service channel \(A_{APA}(t)\) are interrelated and the fluctuations of \(A_{APA}(t)\) is one of the root cause of electric power communication failure events [26]. Because the fluctuations of \(A_{APA}(t)\) has the random nature according to the interaction of many factors, the occurrence of the electric power communication failure event is a complex random process. Moreover, the fluctuations of \(A_{APA}(t)\) makes the occurrence of the events that violate the availability rules (i.e., service channel failure events (SFE)) inevitable and hard to be precisely tracked. Therefore, it is necessary to precisely quantify the occurrence rule of SFE and _SCVR_. The preliminary work in paper [27] adopted the influence factors of service channel availability (_FN_ and _TTR_) instead of \(A_{APA}(t)\) to equivalently quantify _SCVR_. It just simply mentioned the idea without mathematical proof. However, it is proved to be an effective way to start with analysis of the influence factors of service channel availability and their relationship. Thus, the study of distribution models of _FN_, failure arrival rate and _TTR_ of transmission equipment and fiber cable and their internal relationship is the fundamental way to precisely quantify _SCVR_ and control the influence degree of electric power communication failure events. According to the analysis above, the innovativeness of this paper are as follows. 1. To precisely track the violation risk change of service channel under the condition that all of the _FN_, failure arrival rate and _TTR_ are random, we deduce _SCVRD_ model from the service channel violation risk model which is denoted by \(A_{APA}(t)\) and denote _SCVRD_ model by the probability of service channel cumulative failure duration exceeding the prescribed duration. We prove the deduction and simplify the _SCVRD_ model with mathematical method. 2. Based on _SCVRD_ model, the _SCVRD-R_ mechanism is proposed to reduce the _FN_ and failure duration of the electric power communication service. The goal is to minimize the violation risk caused by the random failures and _TTR_ of transmission equipment and optical cable and thus to improve the availability of electric power communication service.