Disclosure of Invention
The invention aims to provide a power communication network routing method for solving the problems of unbalanced load flow and risk of a power communication network so as to improve the reliability of the power communication network and reduce the operation risk of jointly balancing the load flow and the service risk.
In order to achieve the purpose, the invention adopts the technical scheme that:
a power communication network routing method jointly balanced by load flow and business risk is used for achieving balanced operation of a power communication network, and comprises the following steps:
step 1: inputting a network topology G ═ V, E, D, W corresponding to the electric power communication network, wherein V represents a node set in the electric power communication network, E represents a link set in the electric power communication network, D represents a link distance matrix of the electric power communication network, and W represents a link capacity matrix of the electric power communication network; respectively initializing the load weight and the risk weight of each link in the network topology G to be 1, and calculating the initial routing weight of each link according to the load weight and the risk weight;
step 2: waiting for a communication request Rq-s, d, B, R, wherein s denotes said communication request RqD represents said communication request RqB represents said communication request RqR represents said communication request RqThe importance of (2);
and step 3: the communication request RqAfter the communication request R arrives, the shortest path method is used as the communication request R based on the routing weight of each link in the network topology GqSearching a working path P (s, d), and if the working path P (s, d) exists, executing the step 4; otherwise blocking the communication request RqTurning to step 2;
and 4, step 4: judging whether the free capacity of all links on the working path P (s, d) is larger than the request bandwidth B, if so, the working path P (s, d) is available, allocating capacity for the working path P (s, d), updating the free capacity of each link in the network topology G, executing the step 5, otherwise, blocking the communication request RqTurning to step 2;
and 5: judging the communication request RqWhether the importance r is greater than or equal to r0,r0If so, executing step 6, otherwise, receiving the communication request RqTurning to step 8;
step 6: deleting the links on the working path P (s, d) from the network topology G, and using a shortest path method for the communication request R based on the routing weight of each linkqSearching the backup path BP (s, d), if the backup path BP (s, d) exists, executing the step 7, otherwise blocking the communication request RqTurning to step 2;
and 7: judging whether the free capacity of all links on the backup path BP (s, d) is larger than the request bandwidth B, if so, the backup path BP (s, d) is available, allocating capacity for the backup path BP (s, d), and receiving the communication request RqUpdating the free capacity of each link in the network topology G, executing step 8, otherwise releasing the capacity allocated to the working path P (s, d) in step 4, and blocking the communication request RqTurning to step 2;
and 8: calculating and updating the load weight of each link in the network topology G;
and step 9: calculating and updating the risk weight of each link in the network topology G;
step 10: and (3) calculating and updating the routing weight of each link in the network topology G, and turning to the step 2.
In step 8, for a link x-y connecting a node x and a node y in the network topology G, a load weight is calculated by the following steps:
step 801: reading the remaining free capacity f (x, y) on the link x-y;
step 802: by using
respectively calculating a traffic admission value lambda (x) of the node x and a traffic admission value lambda (y) of the node y; wherein v represents any node except the node x/the node y in the network topology G, W (x, v)/W (y, v) is an initial capacity of the path x-v/path y-v, f (x, v)/f (y, v) is a free capacity of the path x-v/path y-v, sgn (x, v)/sgn (y, v) are variables of 0 or 1, respectively, when the node x/node y is adjacent to the node v, sgn (x, v)/sgn (y, v) takes 1, otherwise takes 0;
step 803: by using
Calculating the load weight C of the link x-yLoad(x, y); wherein, C0And (x, y) is the initial weight of the link x-y, and W (x, y) is the initial capacity of the link x-y.
The initial capacity W (x, y) of the link x-y is obtained by multiplying the number of cores of the cable by the transmission capacity of the cable per core.
Initial weight C of the link x-y0(x, y) is determined by cable length or routing cost.
In step 9, for a link x-y connecting a node x and a node y in the network topology G, a risk weight is calculated through the following steps:
step 901: by using
p(x,y)=AD(x,y)
Calculating the normal working probability p (x, y) of the link x-y; where D (x, y) represents the physical length of the link x-y, A represents the availability per kilometer of fiber,
wherein MTTF refers to the average working time before the optical fiber fails, MTTR refers to the average value of the optical fiber fault repairing time, and the unit of MTTF and MTTR is hour;
step 902: by using
Calculating the business risk R (x, y) of the link x-y; wherein N represents the total number of services carried on the link x-y, riRepresenting the importance of the ith service;
step 903: by using
Calculating the maximum service risk value R which can be borne by the link x-yM(x, y); wherein, BminRepresents the minimum value of all service request bandwidths, rmaxMaximum value representing the importance of all service requests;
step 904: by using
Calculating the risk weight C of the link x-yRisk(x,y)。
In the step 10, for a link x-y connecting a node x and a node y in the network topology G, a routing weight is calculated through the following steps:
step 1001: by using
Load weight C to the link x-y
Load(x, y) is subjected to homogenization processing and mapped to the interval [0,1]]The value of the load weight of the link x-y after homogenization is obtained
Wherein
Is the maximum of the load weights of all links,
the load weight of all links is the minimum value;
step 1002: by using
A risk weight C for the link x-y
Risk(x, y) intoLine uniformization processing, mapping it to the interval [0,1]]The value of the risk weight of the link x-y after homogenization is obtained
Wherein
Is the maximum of the risk weights for all links,
the minimum value of the risk weight of all links is obtained;
step 1003: introducing a value of a balance factor alpha after load weight of the link x-y is normalized
And the value of the risk weight after homogenization
Make an adjustment using
Calculating a routing weight C (x, y) of the link x-y; wherein alpha is more than or equal to 0 and less than or equal to 1.
In step 1, the initial routing weight of each link is calculated by using the route weight (α load weight + (1- α) × risk weight).
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the invention provides a routing method for load flow and service risk joint balancing, aiming at the defects of the load and risk balancing routing algorithm of the current power communication network, namely the problems that most algorithms are respectively designed aiming at load balancing and risk balancing and rarely consider the load balancing and the risk balancing at the same time. In the aspect of load flow balance, the invention considers the occupation condition of a link channel and the admission condition of node flow, and further designs a load weight calculation function of a link; in the aspect of service risk balance, the availability of the optical fiber link of the power communication network is modeled, and a balance strategy considering service priority and service risk carried by the link is further designed; and finally, introducing balance factors to construct a link cost function comprehensively considering load and risk so as to realize the joint balance of the current-carrying capacity and the service risk. The invention can adjust the balance factor according to the importance degree of the service, can simultaneously reduce the blocking rate and the service risk of the network, balance the load flow and the risk value of the link, and finally enable the network to achieve the best performance.
Detailed Description
The invention will be further described with reference to examples of embodiments shown in the drawings to which the invention is attached.
The first embodiment is as follows: as shown in the attached figure 1 of the drawings,
a power communication network routing method for realizing joint balancing of load flow and business risk of balanced operation of a power communication network comprises the following steps:
step 1: in the control system of the power communication network, a network topology G corresponding to the input power communication network is (V, E, D, W), wherein V represents a node set in the power communication network, E represents a link set in the power communication network, D represents a link distance matrix of the power communication network, W represents a link capacity matrix of the power communication network, and | V | and | E | represent the total number of nodes and the total number of links in the power communication network respectively. Then respectively initializing the load weight and the risk weight of each link in the network topology G to be 1, and calculating the initial routing weight of each link according to the load weight and the risk weight. A balance factor alpha is correspondingly introduced into each link in the network topology G, and the initial routing weight of each link is calculated by using the routing weight (alpha load weight + (1-alpha) × risk weight), wherein the used load weight is an initial value 1, the risk weight is an initial value 1, and the balance factor alpha belongs to the interval of [0,1 ].
Step 2: waiting for a communication request RqWhere s denotes a communication request RqD denotes a communication request RqB represents a communication request RqR denotes a communication request RqThe importance of (c).
And step 3: communication request RqAfter the communication request R arrives, the shortest path method is used as the communication request R based on the routing weight of each link in the network topology GqSearching a working path P (s, d), and if the working path P (s, d) exists, executing the step 4; otherwise block the communication request RqAnd turning to step 2. When communication request RqAnd (3) when the communication request is the first communication request, searching the routing weight of the link utilized in the working path, namely the initial routing weight calculated in the step (1). If communication request RqAnd when the communication request is not the first communication request, searching the routing weight of the link utilized in the working path, namely the routing weight calculated in the previous communication request.
And 4, step 4: judging whether the free capacity of all links on the working path P (s, d) is larger than the request bandwidth B, if so, the working path P (s, d) is available, allocating capacity for the working path P (s, d), updating the free capacity of each link in the network topology G, executing the step 5, otherwise, blocking the communication request RqAnd turning to step 2.
And 5: judging a communication request RqWhether the importance r is greater than or equal to r0,r0If so, executing step 6, otherwise, receiving the communication request RqAnd turning to step 8.
Step 6: deleting the links on the working path P (s, d) from the network topology G, and using the shortest path method as the communication request R based on the routing weight of each linkqSearching the backup path BP (s, d), if the backup path BP (s, d) exists, executing the step 7, otherwise, blockingPlug communication request RqAnd turning to step 2. When communication request RqWhen the backup path is the first communication request, the route weight of the link used in searching the backup path is the initial route weight calculated in step 1. If communication request RqAnd when the backup path is not the first communication request, searching the routing weight of the link utilized in the backup path, namely the routing weight calculated in the previous communication request.
And 7: judging whether the free capacity of all links on the backup path BP (s, d) is larger than the request bandwidth B, if so, the backup path BP (s, d) is available, allocating the capacity for the backup path BP (s, d), and receiving the communication request RqUpdating the free capacity of each link in the network topology G, executing step 8, otherwise releasing the capacity allocated for the working path P (s, d) in step 4, blocking the communication request RqAnd turning to step 2.
And 8: and calculating and updating the load weight of each link in the network topology G.
For a link x-y connecting a node x and a node y in a network topology G, calculating a load weight of the link x-y by the following steps:
step 801: reading the remaining free capacity f (x, y) on the link x-y;
step 802: for a node (e.g., node x or node y), its traffic admission value is defined as the ratio of the sum of the free capacity on all links connected to the node to the sum of the initial capacity on those links. Thus, utilize
respectively calculating a traffic admission value lambda (x) of a node x and a traffic admission value lambda (y) of a node y; wherein v represents any node except for a node x/a node y in a network topology G, W (x, v)/W (y, v) is the initial capacity of a path x-v/a path y-v, f (x, v)/f (y, v) is the idle capacity of the path x-v/the path y-v, sgn (x, v)/sgn (y, v) are respectively a variable of 0 or 1, when the node x/the node y is adjacent to the node v, namely the path x-v/the path y-v forms a link x-v/a link y-v, sgn (x, v)/sgn (y, v) takes 1, otherwise takes 0;
step 803: by using
Calculating load weight C of link x-yLoad(x, y); wherein, C0(x, y) is the initial weight of the link x-y, which is determined by the cable length or the route cost, the longer the cable length, the initial weight C of the link x-y0The larger (x, y) is, the higher the routing cost is, and the initial weight C of the link x-y is0The larger (x, y); w (x, y) is the initial capacity of the link x-y, and is obtained by multiplying the number of cores of the optical cable by the transmission capacity of each core of the optical cable.
And step 9: and calculating and updating the risk weight of each link in the network topology G.
For a link x-y connecting a node x and a node y in a network topology G, calculating a risk weight by the following steps:
step 901: by using
p(x,y)=AD(x,y)
Calculating the normal working probability p (x, y) of the link x-y; where D (x, y) represents the physical length of link x-y in km, A represents the availability per km of optical fibre,
wherein MTTF refers to the average working time before the optical fiber fails, MTTR refers to the average value of the optical fiber fault repairing time, and the unit of MTTF and MTTR is hour;
step 902: for link x-y, its traffic risk is defined as the sum of the products of the importance of all traffic carried on link x-y and the probability of failure of link x-y, i.e. utilization
Calculating the business risk R (x, y) of the link x-y; wherein N represents on link x-yTotal number of services carried, riRepresenting the importance of the ith service;
step 903: by using
Calculating the maximum service risk value R that the link x-y can bearM(x, y); wherein, BminRepresents the minimum value of all service request bandwidths, rmaxMaximum value representing the importance of all service requests;
step 904: by using
Calculating risk weight C of link x-yRisk(x, y) where lnA is the logarithm of A based on e.
Step 10: and (5) calculating and updating the routing weight of each link in the network topology G, and turning to the step 2.
For a link x-y connecting a node x and a node y in a network topology G, calculating a routing weight value by the following steps:
step 1001: by using
Load weight C for link x-y
Load(x, y) is subjected to homogenization processing and mapped to the interval [0,1]]The value of the load weight of the link x-y is obtained
Wherein
Is the maximum of the load weights of all links,
the load weight of all links is the minimum value;
step 1002: by using
Risk weight C for link x-y
Risk(x, y) is subjected to homogenization processing and mapped to the interval [0,1]]The value of the risk weight of the link x-y is obtained
Wherein
Is the maximum of the risk weights for all links,
the minimum value of the risk weight of all links is obtained;
step 1003: introducing a value of a balance factor alpha after the load weight of the link x-y is normalized
And the value of the risk weight after homogenization
Make an adjustment using
Calculating a routing weight value C (x, y) of the link x-y; the balance factor alpha can be adjusted according to the service importance degree, alpha is more than or equal to 0 and less than or equal to 1, and if the service importance degree is higher, the balance factor alpha is smaller.
And (3) taking the calculated routing weight of each link as the routing weight of each link in the next routing, sending the routing weight to a routing module of the power communication network for updating and storing, waiting for the next communication request after turning to the step 2, and searching for a working path and a backup path by using the previously calculated routing weight when the next communication request arrives.
Fig. 2 is a schematic diagram of calculating a node traffic admission value in the present invention.
The underlying medium of the transmission network is a cable routing network, and it is assumed that the capacity of some links in the power communication network at a certain time is occupied as shown in fig. 2. The labels on the links in the figure indicate the available free capacity and the labels indicate the total capacity that the link can provide. For example, the total capacity of the links a-b is 96, the available free capacity is 34, i.e., W (a, b) is 96 and f (a, b) is 34. According to the definition in step 802, here
Therefore, the traffic admission value λ (a) of node a may be set to 157/316, which is 0.50, and λ (b) may be set to 0.35. In the initial stage of the network, namely when no service is transmitted, the traffic admission values of all the nodes are 1, and as the transmission intensity of the service increases, the nodes start to transmit the service, and the traffic admission values gradually decrease.
Fig. 3 is a simulation network of the power communication network routing method for jointly balancing load flow and business risk according to the present invention.
The optical cable network consists of 29 transformer substation communication stations of 220kV or more and 48 optical cable links with different fiber core numbers, and the node average degree is 3.3. In the figure, the station No. 14 is a dispatching center, the stations No. 5, 20 and 29 are 500kV substations, the rest stations are 220kV substations, and the number and the length of the optical fiber cores are marked in the figure. For example, "36F/13.3 km" means that the number of the optical cable cores is 36 and the length is 13.3 km. The dashed links in the figure are the cable lines that are to be built and put into operation. In step 901, according to the literature, the MTTF and MTTR values of the power optical fiber per kilometer are 7600h and 12h, respectively, and it is assumed that the services are randomly distributed in the network. Electric power communication services are classified into 5 types: the class I service is 500kV/220kV relay protection service, and the importance degree is 0.99; the class II service is a stable system, and the service importance is 0.94; the class III service is wide-area phasor measurement, scheduling automation, scheduling telephone and electric energy metering service, and the importance degree is 0.62; the IV-type service is the video monitoring, video consultation and protection information management service of the transformer substation, and the importance degree is 0.29; the class V service is office automation, administrative telephone and cloud terminal application service, and the importance degree is 0.13. Further, the equalization factor α in step 1003 is taken to be 0.45.
Fig. 4 is a comparison result of the blocking rate of the Load and task Balance (LRJB) and the Load Balance Technique (LBT) of the present invention and the Risk Balance routing Technique (MFRL-PP) of the present invention under different service request numbers.
The blocking rate is defined as the ratio of the blocked communication requests to the total number of initiated requests. As can be seen from fig. 4, as the number of service requests increases, the blocking rate of each algorithm gradually increases, wherein the blocking rate of LBT is the lowest, the blocking rate of MFRL-PP is the highest, and the blocking rate of LRJB is slightly higher than that of LBT. This is because LBT designs a routing cost function considering the link capacity state, which can effectively reduce congestion; while MFRL-PP does not take into account the initial capacity of the link and the state of the node. The blocking rate of an LRJB is very close to a typical load balancing algorithm, and the more traffic requests the closer. This indicates that the LRJB load balancing effect is comparable to LBT, but the risk balancing effect is better than LBT, which can make the risk value of the network smaller.
Fig. 5 is a comparison of the standard deviation of the risk of each algorithm link under different service request numbers. Wherein the link risk standard deviation is defined as:
in the formula: rEIs the link risk standard deviation; e is the set of links in the network; | E | represents the total number of links in the network; r (x, y) is the risk of link x-y, defined in step 902; μ is the average of the risks of the links in the network.
In fig. 5, as the traffic in the network increases, the standard deviation of the risk value of each link gradually increases, which is determined by the convergence characteristics of the power communication traffic. The risk standard deviation of LBT without considering link risk at all is much higher than MFRL-PP and LRJB, and the more traffic-intensive the gap is larger. The risk standard deviation of the LRJB is the lowest of the three when the request number is less than 13000, and is 0.78 lower than the MFRL-PP and 5.70 lower than the LBT on average; the standard deviation is slightly higher than the MFRL-PP after the number of requests exceeds 13000. This indicates that the risk balance effect of LRJB is similar to MFRL-PP, but its blocking rate is lower than MFRL-PP.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.