A method for meeting the QoS of wireless multi-service communication on the substation side of a smart grid

Abstract

The present invention relates to a method for meeting the QoS of wireless multi-service communication on the substation side of a smart grid, comprising the following steps: establishing a communication platform on the substation side of the smart grid; constructing a micro-power wireless communication scheme for the access of multi-service terminals; the micro-power wireless communication scheme is a self-organizing network using Wi-SUN / ZigBee technology and containing micro-power network nodes and coverage enhancement nodes, taking the minimum overall throughput of the network as the objective function, and using a preset algorithm to solve the objective function to determine the positions of the micro-power network nodes and the coverage enhancement nodes; performing data transmission through the self-organizing network using an adaptive frequency hopping algorithm, performing data sharing and updating through the communication platform on the substation side of the smart grid, and before the end of the scheduling period, updating various parameters to prepare for entering the next scheduling period. The present invention can meet the QoS requirements of various services on the substation side of the power grid.

Description

Technical Field

[0001] The present invention relates to the technical field of communication on the plant side of smart grid, and particularly to a method for meeting the QoS of wireless multi-service communication on the plant side of smart grid. Background Art

[0002] The plant side mainly includes substations, converter stations, etc. The communication system in the substation has always been mainly wired. Ethernet is used in the station control layer and process layer, and bare optical fibers or buses are used for intelligent terminal devices. However, in recent years, mobile inspection robots, electronic tags, etc. have been gradually popularized in substations, and wireless sensing elements have been installed on main equipment, such as sleeve dielectric loss, body vibration, mechanical characteristic intelligent sensors, environmental monitoring sensors, VR / AR wearable inspection devices, handheld mobile terminal devices, etc. Therefore, the proportion of wireless communication in the plant side is increasing.

[0003] However, in the current business communication on the plant side of smart grid, there are problems of being strongly electromagnetic interfered when performing co-frequency wireless multi-service communication, and at the same time, when a co-frequency wireless multi-service communication node fails, manual intervention is required, which affects the normal operation of the entire system. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for meeting the QoS of wireless multi-service communication on the plant side of smart grid, which can meet the QoS requirements of each service on the plant side of the grid.

[0005] The technical solution adopted by the present invention to solve its technical problems is: to provide a method for meeting the QoS of wireless multi-service communication on the plant side of smart grid, including the following steps:

[0006] Establish a communication platform on the plant side of smart grid;

[0007] Construct a micro-power wireless communication solution for accessing multi-service terminals; the micro-power wireless communication solution is a self-organizing network using Wi-SUN / ZigBee technology and containing micro-power network nodes and coverage enhancement nodes, and taking the minimum throughput of the overall network as the objective function, and using a preset algorithm to solve the objective function to determine the positions of the micro-power network nodes and coverage enhancement nodes;

[0008] Perform data transmission through the self-organizing network using an adaptive frequency hopping algorithm, perform data sharing and updating through the communication platform on the plant side of smart grid, and before the end of the scheduling period, update various parameters to prepare for entering the next scheduling period

[0009] The intelligent grid substation - side communication platform includes a process layer, an interval layer, and a station control layer; the station control layer is used to control and detect the in - station equipment and communicate with a remote dispatching or control center; the interval layer is used to realize the communication between the process layer and the station control layer, and protect and control the operation of primary equipment; the process layer is used to detect the state parameters of operating equipment and realize the execution and drive of equipment.

[0010] The station control layer includes a station control layer network, which is used to realize data interaction between the equipment in the station control layer and the equipment in the interval layer, between the equipment in the station control layer, and between the equipment in the interval layer.

[0011] The process layer includes a process layer network, which is used to realize the communication between the equipment in the process layer and the equipment in the interval layer.

[0012] The objective function is Where D ij represents the amount of transmitted data between the i - th micro - power network node and the j - th coverage enhancement node, B ij represents the transmission bandwidth between the i - th micro - power network node and the j - th coverage enhancement node, represents the position of the i - th micro - power network node in space, represents the position of the j - th coverage enhancement node in space, Ri represents the effective wireless communication coverage radius of the i - th micro - power network node, Sj represents the coverage radius of the j - th coverage enhancement node, n represents the number of micro - power network nodes, and k represents the number of coverage enhancement nodes.

[0013] When using a preset algorithm to solve the objective function, the ant colony algorithm is used to solve the objective function.

[0014] The adaptive frequency - hopping algorithm means that after receiving a frequency - hopping signal, it first performs de - hopping, and then uses a locally synchronized PN code to control the frequency synthesizer to perform frequency hopping according to the signal hopping rule, forming a modulation signal in a fixed carrier. Digital information can be restored through intermediate - frequency filtering and information demodulation; the hopping rate is Where R is the hopping rate, T c is the frequency - hopping dwell time, and T′ represents the time from one frequency to another frequency.

[0015] The self - organizing network containing micro - power network nodes and coverage enhancement nodes constructed using Wi - SUN / ZigBee technology expands the number of node accesses through a network coordinator.

[0016] The self-organizing network containing micro-power network nodes and coverage enhancement nodes constructed by Wi-SUN / ZigBee technology realizes data integrity check and authentication functions through encryption algorithms, reserves dedicated time slots for communication services requiring fixed bandwidth through a collision avoidance mechanism, and ensures that the next data packet can only be sent after receiving an acknowledgment message through an acknowledged data transmission mechanism.

[0017] Beneficial effects

[0018] Due to the adoption of the above technical solutions, compared with the prior art, the present invention has the following advantages and positive effects:

[0019] Through the self-organizing function of Wi-SUN / ZigBee, etc., the present invention does not require manual intervention. Network nodes can sense the presence of other nodes, determine connection relationships, and form a structured network. The self-healing function of Wi-SUN / ZigBee can add or delete a node. When a node fails or its position changes, the network can self-correct and correspondingly adjust the network topology structure without human intervention, ensuring the normal operation of the entire system.

[0020] By adopting self-organizing technologies such as Wi-SUN / ZigBee to construct a co-frequency wireless multi-service communication network, the present invention can suppress strong electromagnetic interference according to the adaptive frequency hopping algorithm for the electromagnetic environment characteristics on the substation side. Frequency hopping means that the used frequency points of each carrier change according to a certain frequency hopping sequence among a preset group of frequency points with the change of frames. Its working principle is that the carrier frequencies of the transmitted and received signals change discretely according to a predetermined rule. That is to say, the carrier frequencies used in communication are controlled by a pseudo-random change code and randomly hop. From the perspective of the frequency domain, the spectrum of the frequency hopping signal is randomly hopping at unequal intervals over a very wide frequency band. Frequency hopping communication also has good anti-interference ability. Even if some frequency points are interfered, normal communication can still be carried out on other non-interfered frequency points, improving the anti-interference ability of wireless communication in a strong electromagnetic environment. Brief description of the drawings

[0021] Figure 1 is a flowchart of an embodiment of the present invention. Detailed implementation manners

[0022] The following further elaborates the present invention in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0023] Embodiments of the present invention relate to a method for meeting the QoS of wireless multi-service communication on the substation side of a smart grid, such as Figure 1 shown, and include the following steps:

[0024] S1. Establish a communication platform on the substation side of the smart grid

[0025] In this step, from the perspective of the logical structure, the structure of the communication platform on the substation side of the smart grid mainly includes three levels: the process layer, the bay layer, and the station control layer.

[0026] Among them, the station control layer is located at the top layer of the entire communication platform and includes an automated substation-level communication system, a time synchronization system, substation area control, a monitoring system, etc. It monitors and alarms the equipment of the entire substation and uploads the status information and alarm information in a wired manner. The main functions of the station control layer are: the control and detection functions of the in-station equipment and the communication function with the remote dispatching or control center.

[0027] The bay layer is mainly composed of secondary equipment, which mainly includes system measurement and control devices, relay protection devices, metering devices, fault recorder devices, etc. The main functions of the bay layer are: issuing control instructions such as priority control statistical operations and data acquisition, real-time summarizing the data of the process layer of this bay, implementing the locking function of the operation of this bay, implementing the communication function of the upper and lower structures, protecting and controlling the operation of primary equipment, implementing operation synchronization and other control functions. Sometimes, in order to ensure the reliability of the communication network, the interfaces of the upper and lower networks need to have a full-duplex working mode.

[0028] The process layer is composed of independent intelligent electronic devices, primary equipment, and their affiliated intelligent components. Among them, the primary equipment mainly includes disconnectors, circuit breakers, current / voltage transformers, transformers, etc. The main functions of the process layer are: real-time detecting various electrical quantities during the operation of the system, mainly the detection of current, voltage, phase, and harmonic components, detecting the state parameters of operating equipment, such as the position information of circuit breakers and disconnectors, and controlling and driving the operation of equipment, such as opening and closing circuit breakers and disconnectors.

[0029] The station control layer also includes a station control layer network. The main services of the station control layer network are data interaction between station control layer devices and bay-level devices, between station control layer devices, and between bay-level devices. The station control layer network mainly transmits station control layer MMS information and bay-level GOOSE information. For substations with a voltage level of 110 kV and below, when the station control layer network and the process layer network are combined into a common network, the station control layer network can also transmit GOOSE trip information for voltage levels of 110 kV and below. The station control layer MMS information is mainly used for network transmission between bay-level devices and station control layer devices, and its content should include data acquisition information, operation and control information, and operation monitoring information. The MMS message uses service forms such as request / response, general call, periodic report upload, burst report upload, and file transfer.

[0030] The process layer also includes a process network layer. The process network layer is the interface between primary equipment and secondary equipment. Or rather, the process layer network is the bridge connecting process layer devices and bay-level devices, and is used to transmit GOOSE information and SV information between process layer devices and bay-level devices. The process layer network transmits GOOSE information between process layer devices and bay-level devices, and its content should include: primary equipment body position signals and alarm information transmitted between devices such as merging units, intelligent terminals, protection devices, measuring and controlling devices, PMUs, and fault recorders, self-check information of merging units and intelligent terminals, protection trip, reclosing information, measuring and controlling remote control closing, opening, and interlocking information, as well as protection failure startup and protection interlocking information.

[0031] S2. Construct a micro-power wireless communication for multi-service terminal access

[0032] Deploy near micro-power wireless nodes that are blocked, such as transformers and indoors, in the substation, add coverage enhancement nodes to enhance coverage. The wireless signals of the blocked nodes are relayed by the coverage enhancement nodes and connected to the cluster head or gateway through multi-hop. Multiple coverage enhancement nodes are required in the substation.

[0033] When there are n micro-power network nodes in the indoor or transformer, N = {N1, N2,... Nn}, assuming that the effective coverage radius of each node's wireless communication is R = {R1, R2,... Rn}, and the number of coverage enhancement nodes is k, and the coverage radius of the coverage enhancement nodes is S = {S1, S2,..., Sk}. The spatial position of the micro-power node is denoted as The spatial position of the coverage enhancement node is denoted as If the coverage enhancement node j can relay the micro-power network node i, then it should satisfy:

[0034] dist(i,j)<Ri+Sj

[0035] Among them,

[0036] When the coverage enhancement node deployment scheme is The overall throughput of the network is:

[0037]

[0038]

[0039] Among them, D ij represents the amount of transmitted data between the i-th micro-power network node and the j-th coverage enhancement node, and B ij represents the transmission bandwidth between the i-th micro-power network node and the j-th coverage enhancement node. The coverage scheme is the following optimization problem:

[0040]

[0041] When the network scale is small, the integer linear programming algorithm can be used for approximate solution. When the network scale is large, the heuristic algorithm can be used, or it can be analyzed through the adaptive neural network algorithm.

[0042] S3. Build network nodes using Wi-SUN / ZigBee technology

[0043] Wi-SUN / ZigBee uses the basic master-slave structure to build network nodes. A Wi-SUN / ZigBee network can accommodate at least 254 slave devices and one master device. Wi-SUN / ZigBee provides data integrity check and authentication functions. At the same time, each application can flexibly determine its security attributes, and dedicated time slots are reserved for communication services that require fixed bandwidth, avoiding competition and conflicts when sending data. In the access layer, a confirmed data transmission mechanism is adopted. Each sent data packet must wait for the confirmation information from the receiving point before sending the next data packet. The self-organizing function of Wi-SUN / ZigBee does not require manual intervention. Network nodes can sense the existence of other nodes and determine the connection relationship to form a structured network; the self-healing function of Wi-SUN / ZigBee can add or delete a node. When a node fails or the node position changes, the network can self-correct and adjust the network topology accordingly without human intervention to ensure the normal operation of the entire system.

[0044] S4. Suppress wireless communication interference in a strong electromagnetic environment

[0045] Suppress strong electromagnetic interference by using an adaptive frequency hopping algorithm based on the electromagnetic environment characteristics on the substation side. Frequency hopping means that the used frequency point of each carrier changes according to a certain frequency hopping sequence among a pre-set group of frequency points as the frame changes. Its working principle is that the carrier frequencies of the transmitted and received signals change discretely according to a predetermined rule. That is to say, the carrier frequencies used in communication are randomly hopped under the control of a pseudo-random change code. From the perspective of the frequency domain, the spectrum of the frequency-hopping signal is randomly hopped at unequal intervals over a very wide frequency band. Frequency-hopping communication also has good anti-interference ability. Even if some frequency points are interfered, normal communication can still be carried out on other non-interfered frequency points.

[0046] After receiving the frequency-hopping signal, first de-hop it. Use the locally synchronized PN code to control the frequency synthesizer to perform frequency hopping according to the hopping rule of the signal s(t), forming the modulation signal w(t) in the fixed carrier. After intermediate frequency filtering and information demodulation, the digital information can be restored.

[0047]

[0048] Among them, is a random quantity, a random value that may change with each hop.

[0049] Frequency hopping rate R:

[0050]

[0051] Among them, T c is the frequency hopping dwell time, and T′ is the time to hop from one frequency to another.

[0052] Assume that the spectrum width of the modulation signal is B, and the adjacent channel interval Δf = |f i+1 -f i | ≥ B. Therefore, when the total number of frequency hopping channels is N, the total RF bandwidth of the frequency-hopping signal is NB. Compared with general modulation methods, the spreading gain brought by frequency hopping is:

[0053] G p = N

[0054] In the present invention, the carrier frequencies used in communication are randomly hopped under the control of a pseudo-random change code. From the perspective of the frequency domain, the spectrum of the frequency-hopping signal is randomly hopped at unequal intervals over a very wide frequency band. Frequency-hopping communication also has good anti-interference ability. Even if some frequency points are interfered, normal communication can still be carried out on other non-interfered frequency points, improving the anti-interference ability of wireless communication in a strong electromagnetic environment.

[0055] S5. Selection of network nodes in Wi-SUN / ZigBee technology

[0056] The RSSI limit of a conventional Wi-SUN / ZigBee wireless ad-hoc network ranges from -85 to 95 dBm. When the RSSI is below the minimum limit, the signal strength cannot guarantee the normal communication of the network. Therefore, the selection of the distance between network nodes is very important. Based on the shortest path calculation of the ant colony algorithm, the ant colony algorithm is an intelligent swarm algorithm that simulates the foraging behavior of ants. Its basic idea is that a large number of ants will release pheromones on the foraging path to mark the path they have walked. At the same time, subsequent ants will tend to choose the path with a higher pheromone concentration. The pheromone concentration of the shorter path between any data collection node and the aggregation receiving node will become higher and higher, and finally the shortest path can be generated. The location of the nodes is selected by using the ant colony algorithm.

[0057] The basic principle of the ant colony algorithm is as follows (Dreo J et al., 2004; Ling C et al., 2002):

[0058] (1) In the initialization stage, the algorithm will set a total of A ants, and the ants will leave pheromones on the paths they pass through.

[0059] (2) If the edge devices encountered by the ants have not been experienced before, then the ants randomly select a device to move forward. At the same time, pheromones are left under the path of movement.

[0060] (3) The size of the pheromone is inversely proportional to the time cost of the path passed through. When subsequent ants select the edge devices they pass through, they will choose the devices with a greater pheromone content on the path with a higher probability.

[0061] (4) The pheromone content on the optimal path continuously increases.

[0062] (5) Finally, the ant colony finds the optimal path based on the pheromone.

[0063] The symbol definition of the ant colony algorithm is as follows

[0064] Definition of the heuristic function:

[0065]

[0066] The heuristic function reflects the influence of the time cost of the communication path on the ant's path selection when the ant turns from device i to device j. It can be seen that the greater the communication time, the smaller the value of the heuristic function, and the smaller the possibility that the ant selects device j as the next stop on the path.

[0067] Definition of the pheromone function:

[0068]

[0069] Among them, It reflects the pheromone value released on the communication path between device i and device j by ant u. When ant u moves from device i to device j, In other cases, Q represents the total amount of pheromone carried by the ant, and d u represents the communication time cost of the entire path from the starting point to the ending point of ant u. Then, according to the above definition, in the case of a total of U ants, the sum of the pheromone update values between device i and device j can be denoted as:

[0070]

[0071] The pheromone updated by the ant on each path will volatilize with the algorithm iteration. The volatilization factor is denoted as ρ, and its value range is (0, 1). Therefore, in the t-th iteration process, for the communication path between device i and device j, the value of the pheromone it has is:

[0072] τ ij (t) = (1 - ρ)τ ij (t) + Δτ ij

[0073] Definition of the transition probability function:

[0074] Based on the heuristic function and the pheromone function, the probability transition function for the ant to select a path can be defined. For ant u, the probability that it transfers from device i to device j at time t is:

[0075]

[0076] Among them, J u (i) represents the set of devices that ant u can select to transfer when it is at device i. If device j satisfies B ij > 0 and in the current iteration round, ant u has never visited this device before, then device j is in J u (i). α and β are the pheromone factor and the heuristic factor respectively, and they respectively reflect the dependence degree of the probability transition function on the pheromone function and the heuristic function.

[0077] S6. Service transmission and update

[0078] Transmit the invoked service through the ad hoc network constructed by Wi - SUN / ZigBee, and perform data sharing and update through the communication platform on the substation side of the smart grid. Before the end of the scheduling cycle, update various parameters and prepare to enter the next scheduling cycle.

[0079] Through the self-organizing function of Wi-SUN / ZigBee, etc., the present invention requires no manual intervention. Network nodes can sense the presence of other nodes, determine the connection relationship, and form a structured network. The Wi-SUN / ZigBee self-healing function can add or delete a node. When a node fails or its location changes, the network can self-correct and make corresponding adjustments to the network topology without human intervention, ensuring the normal operation of the entire system.

Claims

1. A method for meeting the QoS of wireless multi-service communication on the substation side of a smart grid, characterized in that, It includes the following steps: Establish a communication platform on the substation side of the smart grid; Construct a micro-power wireless communication solution for multi-service terminal access; the micro-power wireless communication solution is a self-organizing network using Wi-SUN / ZigBee technology, which contains micro-power network nodes and coverage enhancement nodes, and takes the minimum throughput of the overall network as the objective function, and uses a preset algorithm to solve the objective function to determine the positions of the micro-power network nodes and the coverage enhancement nodes; where the objective function is: Among them, D ij represents the amount of transmitted data between the i-th micro-power network node and the j-th coverage enhancement node, and B ij represents the transmission bandwidth between the i-th micro-power network node and the j-th coverage enhancement node, represents the position of the i-th micro-power network node in space, represents the position of the j-th coverage enhancement node in space, Ri represents the effective wireless communication coverage radius of the i-th micro-power network node, Sj represents the coverage radius of the j-th coverage enhancement node, n represents the number of micro-power network nodes, and k represents the number of coverage enhancement nodes; Adopt an adaptive frequency hopping algorithm for data transmission through the self-organizing network, conduct data sharing and update through the communication platform on the substation side of the smart grid, and update various parameters to prepare for the next scheduling cycle before the end of the scheduling cycle.

2. The method for satisfying wireless multi-service communication QoS on the plant side of the smart grid according to claim 1, characterized in that, The communication platform on the substation side of the smart grid includes a process layer, an interval layer, and a station control layer; the station control layer is used to control and detect the in-station equipment and communicate with a remote dispatching or control center; the interval layer is used to realize the communication between the process layer and the station control layer, and protect and control the operation of primary equipment; the process layer is used to detect the state parameters of operating equipment and realize the execution and drive of equipment.

3. The method for meeting the QoS of wireless multi-service communication on the substation side of the smart grid according to claim 2, characterized in that, The station control layer includes a station control layer network, and the station control layer network is used to realize data interaction between the equipment in the station control layer and the equipment in the interval layer, between the equipment in the station control layer, and between the equipment in the interval layer.

4. The method for meeting the QoS of wireless multi-service communication on the substation side of the smart grid according to claim 2, characterized in that, The process layer includes a process layer network, and the process layer network is used to realize the communication between the equipment in the process layer and the equipment in the interval layer.

5. The method for meeting the QoS of wireless multi-service communication on the substation side of the smart grid according to claim 1, characterized in that, When solving the objective function using a preset algorithm, the ant colony algorithm is used to solve the objective function.

6. The method for satisfying wireless multi-service communication QoS on the plant side of the smart grid according to claim 1, wherein The adaptive frequency hopping algorithm means that after receiving the frequency hopping signal, it first performs de-hopping, and then uses the locally synchronized PN code to control the frequency synthesizer to perform frequency hopping according to the hopping law of the signal, forming a modulation signal in a fixed carrier. The digital information can be restored through intermediate frequency filtering and information demodulation; the hopping rate is where R is the hopping rate, and T c is the frequency hopping dwell time, and T′ represents the time from one frequency to another frequency.

7. The method for satisfying wireless multi-service communication QoS on the substation side of the smart grid according to claim 1, wherein The self-organizing network constructed by using Wi-SUN / ZigBee technology and containing micro-power network nodes and coverage enhancement nodes expands the number of node accesses through a network coordinator.

8. The method for meeting the QoS of wireless multi-service communication on the substation side of the smart grid according to claim 1, characterized in that, The self-organizing network constructed by using Wi-SUN / ZigBee technology and containing micro-power network nodes and coverage enhancement nodes realizes data integrity check and authentication functions through an encryption algorithm, reserves dedicated time slots for communication services that require fixed bandwidth through a collision avoidance mechanism, and ensures that only after receiving an acknowledgment message can the next data packet be sent through a confirmed data transmission mechanism.

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