Background
The ubiquitous power internet of things is the second network in the three-type two-network, the interconnection of everything and the man-machine interaction of all the services in power operation are realized through advanced technologies such as big-cloud-thing-moving-intelligence, edge calculation, block chains and the like, all people, things and equipment related to a power grid are connected, data sharing and fusion and comprehensive service communication are promoted for one source of data, one graph of the power grid and one line of the service, and meanwhile, various services are widely connected to the outside, the service range is expanded, and service objects are expanded.
Different from the existing power communication network and information system, the ubiquitous power internet of things has the full-state perception and full-service penetration capacity of all links of equipment and users in the whole period of an energy system, and is connected with power infrastructure, government industry mechanisms, users and suppliers in a full-time and full-space mode, so that data fusion is promoted, safe open sharing is realized, energy internet service innovation is promoted, and higher-quality service is provided for customers.
Numerous high-voltage and low-voltage power equipment are distributed in a ubiquitous power internet of things scene, so that a large amount of power data, namely equipment running state data, need to be collected, and a large amount of wireless internet of things nodes are arranged in various equipment in a power system scene and used for completing collection and transmission of various power equipment data in the ubiquitous power internet of things.
However, the distributed environments of various devices of the power system are mostly complex urban environments or harsh wild unmanned environments, various noises in the environments can affect the normal work of the data acquisition and transmission functions of the nodes of the wireless internet of things, in order to achieve the rapid acquisition and stable, complete and reliable transmission of data in the power system, the nodes with the optimal routing performance in the power internet of things need to be selected for data transmission at different times in different states, and the factors affecting the routing performance of the nodes are numerous, so that the routing performance of the nodes needs to be evaluated by comprehensively considering the transmission requirements of different data, real-time environmental conditions and the states of the nodes.
In the prior art, the research on the communication effect of the wireless communication network mainly considers indexes such as path length, channel bandwidth, average communication traffic, communication overhead, bit error rate, packet loss rate, time delay and the like, and the performance of the whole path is mainly evaluated through a single index, so that the network performance and the routing performance of a single node cannot be comprehensively reflected. In addition, various interferences exist in the distribution area of the power internet of things, especially in the environment of high-density distribution of network nodes, the working performance of each network node is also related to the transmission error rate, packet loss rate, transmission energy consumption and transmission delay of the node, and a relay node with the optimal performance cannot be selected by considering a single index, so that the routing performance of the node needs to be evaluated by combining a plurality of indexes. Nodes of the power internet of things are mostly deployed in a severe unmanned environment, and power consumption reduction is necessary, and in a wireless communication network of the power internet of things, due to different types of transmission data, the requirements on real-time performance and reliability of the network are different, and the existing routing method does not consider the requirements of different types of data transmission in the network.
Disclosure of Invention
The invention aims to provide a dynamic evaluation method for node routing performance when different types of data are transmitted in a wireless communication network of the power internet of things, and particularly relates to a wireless communication node routing performance evaluation method of the power internet of things.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention assumes that a limited three-dimensional region to be monitored distributed by a wireless communication network in the power Internet of things has the following properties:
1) the wireless communication node location within the area is fixed;
2) the landform and the landform in the area are kept unchanged;
3) each wireless communication node in the area is isomorphic, namely has the same transmitting, receiving and processing capacity;
4) the network communication link is bidirectional, i.e., node i and node j are capable of bidirectional communication.
Assuming that N wireless communication network nodes are randomly deployed in a limited three-dimensional area to be monitored where the wireless communication network of the power internet of things with the above properties is located, the coordinate of the ith node is (x)i,yi,zi) The root node is placed in the center of the monitoring area and serves as the origin of a coordinate system of the whole three-dimensional area to be monitored, each wireless communication network node transmits collected data to the root node in a single-hop or multi-hop mode, and the root node transmits the gathered data to the terminal management node in an internet or optical fiber communication mode.
A method for evaluating routing performance of wireless communication nodes of an electric power Internet of things comprises the following steps:
step (1), judging the data type D which needs to be transmitted currently by the wireless communication node i of the power internet of thingst;
The traditional power system communication network divides the transmitted data into three types of common data (without real-time and reliability requirements), real-time data (with high real-time requirements) and reliability (with high reliability requirements), and combines the characteristics of the power internet of things, the invention divides the data D transmitted in the power internet of thingstThe method is divided into the following three categories: common power data, equipment state data and control instruction data;
step (2) of transmitting a data type D according to the node i obtained in the step (1)tConstructing a corresponding node routing performance evaluation model parameter weighted value;
wherein alpha isj、βj、θj(j ═ 1,2, …,5) respectively represents the weight value of each parameter in the node routing performance evaluation model when the node transmits different types of data; j is 1,2,3,4,5 corresponding to delay, packet loss rate, error rate, adjusting time and node energy consumption respectively; dtIndicating the type of data transmitted, Dt0 denotes that the transmission data is normal power data, Dt1 denotes that the transmission data is device status data, Dt2 represents that the transmission data is control quality data;
step (3), acquiring real-time routing performance data of the node i, including time delay, packet loss rate, bit error rate, adjustment time and node energy consumption, namely Tdelay(i),fpack_loss(i),fwrong_code(i),Tadj_time(i), fpower(i);
3.1 time delay
Due to the fact that the wireless communication network of the power internet of things is interfered by factors such as noise and load, routing delay changes. In addition, the routing delay is also influenced by factors such as signal transmission speed, physical distance, routing congestion degree and the like, so that the delay is an effective index for measuring the real-time performance of routing nodes. Latency refers to the time required for data (a message or packet, or even a bit) to travel from one end of a network or link to the other. The delay of a node comprises a transmission delay Tsend(i) Propagation delay Tspread(i) Processing time delay Tprocess(i) Queuing delay TQuen(i);
And (3) sending delay: is the time required from the transmission of the first bit of a data frame to the completion of the transmission of the last bit of the frame.
Tsend(i)=Ldata*WchannelFormula (2)
Wherein L isdataIndicating the length, W, of the data frame to be transmitted by the nodechannelRepresenting the channel bandwidth of the node communication;
propagation delay: the time it takes for an electromagnetic wave to travel a certain distance in a channel.
Wherein VelecRepresenting the transmission rate, L, of electromagnetic waves on a node communication channelchannelIndicating the length of the channel over which the node communicates.
Processing delay: the time at which the host or router processes the received packet.
Queuing delay: packets are queued for processing in the input queue and are queued for forwarding in the output queue, creating a queuing delay.
The total delay T of the node may be defineddelay(i) Comprises the following steps:
3.2 packet loss Rate
In the wireless communication network of the power internet of things, routing congestion often causes loss of service data information, and finally causes continuous reduction of reliability of a low-voltage distribution network, thereby seriously affecting operation of a power system. In addition, channel capacity, node loading conditions, etc. can also lead to communication failures between network nodes and between nodes and concentrators. Therefore, the packet loss rate is also an important index for measuring the reliability of the routing node.
Packet loss rate: refers to the ratio of the number of lost packets to the number of transmitted packets during data transmission.
Wherein DlossIndicating the number of data packets lost by a node in the process of sending data to the next node; dsumRepresenting the total amount of data packets sent by the node i to the next node;
3.3 bit error rate
The error code is generated because the voltage of the signal is changed by decay in the signal transmission, so that the signal is damaged in the transmission, and the error code is generated. Noise, pulses from ac or lightning, transmission equipment failure, and other factors can cause bit error rates (e.g., a 1 for the transmitted signal and a 0 for the received signal; and vice versa).
Digital signals inevitably produce errors during transmission for a variety of reasons. For example, external interference during transmission, or distortion of the transmitted signal due to the inadequate quality of the various components within the communication system. When the interference or signal distortion is present to a certain extent, errors occur. In data communication, if a transmitted signal is "1" and a received signal is "0", it is "error code", that is, an error occurs.
The bit error rate is an index for measuring the data transmission accuracy in a specified time. The wireless communication network of the power internet of things is mainly used for transmitting service data information of a low-voltage power distribution network, and once error codes appear in transmitted data, the communication quality of the network is reduced, so that the error codes are also an important index for measuring the reliability of routing nodes.
Error rate: the ratio of the number of errors occurring during data transmission to the total number of codes transmitted is indicated.
Wherein, CwrongRepresenting the number of error codes of the node in the process of sending data to the next node; csumRepresenting the total code number of data sent by the node i to the next node;
3.4 adjusting time
On one hand, as the wireless communication network of the power internet of things is used for acquiring and transmitting various equipment state data and power data in the links of power transmission, power distribution, electric energy and the like in a power system, strong electromagnetic interference can exist to influence data acquisition and transmission; on the other hand, the environment where the power transmission and distribution equipment is located in the power internet of things is complex, and various environmental noises can influence the communication function of the power transmission and distribution equipment. The stability of the selected node is therefore important for the implementation of the network communication function.
The invention defines the adjustment time Tadj_time(i) Calculating the maximum time required from the time when the node i receives the complete data packet sent by the previous node i-1 to the time when the node i sends the received complete data packet to the next node i + 1;
3.5 node energy consumption
In order to reduce the energy consumption, it is necessary to select a routing path with high communication efficiency and low energy consumption. The invention defines the sum of the products of the power of different states of a node and the duration of the corresponding state as the energy consumption of the node. Wherein the power of the individual nodes includes transmit power, receive power, and power in a sleep state. Since the energy consumed by the node in the sleep state is negligible relative to the energy consumed in the transmit and receive states, the energy consumption of node i can be formulated as follows:
fpower(i)=k[Psend*t1+Preceive*t2] (7)
wherein f ispower(i) The total energy consumed in the whole process from the point i receiving the kbit data to the point i completely sending the kbit data is expressed and called as the point energy consumption; psendRepresenting the transmission power, t, of node i1Representing the time required by the node i to completely send 1bit data; preceiveDenotes the received power, t, of node i2Representing the time required by the node i to completely receive 1bit data; k represents the amount of data sent by node i in units of bit.
And (4) in the wireless communication network of the power internet of things, communication data information in the node interaction process is possibly lost due to interference of factors such as noise and load, so that the routing performance of the communication network of the low-voltage switch cabinet is seriously influenced. In addition, the invention defines the adjustment time and the node energy consumption as new parameters, and establishes a model for evaluating the node routing performance by combining the delay, the packet loss rate and the bit error rate which are 5 parameters in total.
The invention considers data type DtThe constraint conditions of (1) constructing a node routing performance evaluation objective function considering time delay, packet loss rate, bit error rate, adjustment time and node energy consumption:
f(i)=min[γ1*Tdelay(i)+γ2*fpack_loss(i)+γ3*fwrong_code(i)+γ4* Tadj_time(i)+γ5*fpower(i)]
wherein gamma is1、γ2、γ3、γ4、γ5Is a weight factor, and γ1+γ2+γ3+γ4+γ51, the size of the data can be changed according to the transmission requirements of different types of data to adjust the time delay, the packet loss rate, the error rate, the adjustment time and the proportion of the node energy consumption; wherein T isdelay(i) Representing the delay of data forwarding of a node i in the wireless communication network of the power internet of things; f. ofpack_loss(i) The packet loss rate of data forwarding of a node i in the wireless communication network of the power internet of things is represented; f. ofwrong_code(i) Representing the error rate of data forwarding of a node i in the wireless communication network of the power internet of things; f. ofadj_time(i) The method comprises the steps that adjustment time for data forwarding of a node i in the wireless communication network of the power internet of things is represented; f. ofpower(i) Representing the energy consumption of data forwarding of a node i in the wireless communication network of the power internet of things; t ismaxRepresents the maximum delay; t is tmaxRepresents a maximum adjustment time; pmaxRepresents the maximum path energy consumption;
considering data type DtThe constraint of (2):
if it is of data type DtThe data is common power data, which refers to common data such as voltage, current, active power, reactive power and the like collected by nodes of the Internet of things in the network, the transmission of the data has low requirements on real-time performance and reliability, and only the data needs to be kept in the transmission processAccording to the integrity and the accuracy, the energy limit of the node is considered, and the weight of the energy consumption of the node is increased, so that the weight of each parameter in the node routing performance evaluation model can be set according to the following rule:
α2(packet loss ratio) is more than or equal to alpha3(bit error rate) is not less than alpha5(node energy consumption) is more than or equal to alpha4(adjustment time) is not less than alpha1(time delay);
if it is of data type DtThe device state data refers to state information of power equipment collected in a network, mainly refers to fault information of the equipment, and transmission of the data has high requirements on real-time performance and accuracy, so that the weight of each parameter in the node routing performance evaluation model needs to be set according to the following rules:
β1(delay) not less than beta4(adjustment time) is not less than beta2(packet loss ratio) is not less than beta3(bit error rate) not less than beta5(node energy consumption);
if it is of data type DtThe instruction data is transmitted in the network and used for controlling the operation of each power device, and the transmission of the data has high requirements on real-time performance and reliability, so that the weights of all parameters in the node routing performance evaluation model need to be set according to the following rules:
β1(delay) not less than beta4(adjustment time) is not less than beta2(packet loss ratio) is not less than beta3(bit error rate) not less than beta5(node energy consumption);
for different transmission requirements of three kinds of data, different parameter weight values are set for the three kinds of data, namely different data, and when the objective function f (i) of the node i is solved, the weight factor gamma is1(time delay), gamma2(packet loss ratio), γ3(bit error rate), γ4(adjustment time) and gamma5The (node energy consumption) values are not the same.
Step (5), obtaining the routing performance data corresponding to the minimum value of the objective function values f (i), namely the transmission type of the node i at the current moment is DtThe data of (2) is the performance data with the best routing performance.
The smaller the value of the objective function f (i), the earlier time transmission type is DtTime-routing of dataThe better the performance.
In addition, in order to achieve the above object, the present invention further provides a device for evaluating routing performance of a wireless communication node of an internet of things, including: the electric power internet of things wireless communication node routing performance evaluation method comprises a memory, a processor and an electric power internet of things wireless communication node routing performance evaluation program which is stored on the memory and can run on the processor, wherein when the electric power internet of things wireless communication node routing performance evaluation program is executed by the processor, the steps of the electric power internet of things wireless communication node routing performance evaluation method are realized.
In addition, to achieve the above object, the present invention further provides a storage medium storing a power internet of things wireless communication node routing performance evaluation program, where the power internet of things wireless communication node routing performance evaluation program is executed by a processor, and the method includes the step of performing the power internet of things wireless communication node routing performance evaluation method.
In addition, to achieve the above object, the present invention further provides an apparatus for evaluating routing performance of wireless communication nodes of an internet of things, including:
the data acquisition module is used for acquiring real-time routing performance data of the nodes, wherein the real-time routing performance data comprises time delay, packet loss rate, error code rate, adjustment time and node energy consumption;
a calculation module for calculating the current transmission data type D of the nodetEvaluating the weight value of the model parameter of the corresponding node routing performance;
and the node routing performance evaluation model module is used for receiving the data obtained by the data obtaining module and the calculating module, obtaining a calculating result according to the target function and further obtaining an evaluation result.
The beneficial effects are as follows:
1. the invention defines two parameters of adjusting time and node energy consumption, establishes a node routing performance comprehensive evaluation model by combining three parameters of bit error rate, packet loss rate and time delay, and can realize more comprehensive evaluation on the node routing performance.
2. According to the invention, the data transmitted in the wireless communication network of the power Internet of things is classified, and the weight factors of all parameters in the node routing performance evaluation model can be adjusted according to different types, so that the transmission requirements of different data can be met when the different types of data are transmitted in the network, and the overall communication effect of the network is optimized.
3. The invention has clear logic, easy realization, good universality and portability.
Detailed Description
The invention is further analyzed with reference to the following detailed drawings.
In the wireless communication network of the power internet of things, all nodes have the function of communicating with the nodes in the communication range of the nodes, have the function of routing forwarding and can forward information including the nodes, the node positions, the transmission distances among the nodes and the node state information which are communicated with the nodes;
FIG. 1 is a schematic diagram of a low-voltage switch cabinet power Internet of things wireless communication network structure according to the method of the invention;
a method for evaluating the routing performance of a wireless communication node of a low-voltage switch cabinet communication network comprises the following steps as shown in figure 2:
step (1), judging the data type D which needs to be transmitted currently by the wireless communication node i of the power internet of thingst(ii) a Wherein data type DtThe method comprises the following steps of (1) including common power data, equipment state data and control instruction data;
step (2) of transmitting a data type D according to the node i obtained in the step (1)tConstructing a corresponding node routing performance evaluation model parameter weighted value;
wherein alpha isj、βj、θj(j ═ 1,2, …,5) respectively represents the weight value of each parameter in the node routing performance evaluation model when the node transmits different types of data; j is 1,2,3,4,5 corresponding to delay, packet loss rate, error rate, adjusting time and node energy consumption respectively; dtIndicating the type of data transmitted, Dt0 denotes that the transmission data is normal power data, Dt1 denotes that the transmission data is device status data, Dt2 represents that the transmission data is control quality data;
step (3), acquiring real-time routing performance data of the node i, including time delay, packet loss rate, bit error rate, adjustment time and node energy consumption, namely Tdelay(i),fpack_loss(i),fwrong_code(i),Tadj_time(i), fpower(i);
3.1 time delay
The delay of a node comprises a transmission delay Tsend(i) Propagation delay Tspread(i) Processing time delay Tprocess(i) Queuing delay TQuen(i);
Tsend(i)=Ldata*WchannelFormula (2)
Wherein L isdataIndicating the length, W, of the data frame to be transmitted by the nodechannelRepresenting the channel bandwidth of the node communication;
wherein VelecRepresenting the transmission rate, L, of electromagnetic waves on a node communication channelchannelIndicating the length of the channel over which the node communicates.
The total delay T of the node may be defineddelay(i) Comprises the following steps:
formula (4)
3.2 packet loss Rate
Wherein DlossIndicating the number of data packets lost by a node in the process of sending data to the next node; dsumRepresenting the total amount of data packets sent by the node i to the next node;
3.3 bit error rate
Wherein, CwrongRepresenting the number of error codes of the node in the process of sending data to the next node; csumRepresenting the total code number of data sent by the node i to the next node;
3.4 adjusting time
Adjusting the time Tadj_time(i) The maximum time required from the time when the node i receives the complete data packet sent by the previous node i-1 to the time when the node i sends the received complete data packet to the next node i +1 is calculated;
3.5 node energy consumption
fpower(i)=k[Psend*t1+Preceive*t2] (7)
Wherein f ispower(i) The total energy consumed in the whole process from the point i receiving the kbit data to the point i completely sending the kbit data is expressed and called as the point energy consumption; psendRepresenting the transmission power, t, of node i1Representing the time required by the node i to completely send 1bit data; preceiveDenotes the received power, t, of node i2Representing the time required by the node i to completely receive 1bit data; k represents the amount of data sent by node i in units of bit.
Step (4), data type D is considered in combinationtThe constraint conditions of the node are used for constructing a node routing performance evaluation objective function considering time delay, packet loss rate, error code rate, adjustment time and node energy consumption:
f(i)=min[γ1*Tdelay(i)+γ2*fpack_loss(i)+γ3*fwrong_code(i)+γ4* Tadj_time(i)+γ5*fpower(i)]
Wherein gamma is1、γ2、γ3、γ4、γ5Is a weight factor, and γ1+γ2+γ3+γ4+γ51, the size of the data can be changed according to the transmission requirements of different types of data to adjust the time delay, the packet loss rate, the error rate, the adjustment time and the proportion of the node energy consumption; wherein T isdelay(i) Representing the delay of data forwarding of a node i in the wireless communication network of the power internet of things; f. ofpack_loss(i) The packet loss rate of data forwarding of a node i in the wireless communication network of the power internet of things is represented; f. ofwrong_code(i) Representing the error rate of data forwarding of a node i in the wireless communication network of the power internet of things; f. ofadj_time(i) The method comprises the steps that adjustment time for data forwarding of a node i in the wireless communication network of the power internet of things is represented; f. ofpower(i) Representing the energy consumption of data forwarding of a node i in the wireless communication network of the power internet of things; t ismaxRepresents the maximum delay; t is tmaxRepresents a maximum adjustment time; pmaxRepresents the maximum path energy consumption;
considering data type DtThe constraint of (2):
if it is of data type DtIs common power data, then satisfies the parameter weight alpha2(packet loss ratio) is more than or equal to alpha3(bit error rate) is not less than alpha5(node energy consumption) is more than or equal to alpha4(adjustment time) is not less than alpha1(time delay);
if it is of data type DtIs the device status data, the parameter weight beta is satisfied1(delay) not less than beta4(adjustment time) is not less than beta2(packet loss ratio) is not less than beta3(bit error rate) not less than beta5(node energy consumption);
If it is of data type DtFor control command data, a parameter weight β is satisfied1(delay) not less than beta4(adjustment time) is not less than beta2(packet loss ratio) is not less than beta3(bit error rate) not less than beta5(node energy consumption);
step (5), obtaining the routing performance data corresponding to the minimum value of the objective function values f (i), namely the transmission type of the node i at the current moment is DtThe data of (2) is the performance data with the best routing performance.