CN115694560A - Low-carbon park group topology prediction and time service method and system based on power line carrier - Google Patents
Low-carbon park group topology prediction and time service method and system based on power line carrier Download PDFInfo
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Abstract
The invention discloses a low-carbon park group topology prediction and time service method and system based on power line carriers. Based on the topological adjacency relation of the monitoring terminals, a synchronous group game is adopted to optimize the route selection decision of the time service data packet, and the time service is further carried out on the monitoring terminals and the electrical equipment in the garden through power line carriers, so that the high-precision low-delay wide-coverage time synchronization of the low-carbon intelligent garden community is realized.
Description
Technical Field
The invention belongs to the field of power line carrier communication, and particularly relates to a low-carbon park group topology prediction and time service method and system based on power line carriers.
Background
At present, china is in an energy transformation stage, and a low-carbon intelligent park cluster taking renewable energy as a main body is constructed under the background of shortage of power supply, so that the method has important meanings of saving energy, reducing emission and improving energy efficiency. The low-carbon operation of the intelligent park group is realized by depending on power services such as flexible load regulation and control, carbon footprint monitoring, electric power spot market transaction and the like on the basis of deploying monitoring terminals on electrical equipment such as park photovoltaic panels, wind turbine generators and electric vehicle charging piles to monitor the electric energy circulation and the equipment operation condition of a park. In the process, the information acquisition of the monitoring terminal and the stable operation of the power service need accurate time synchronization. On the one hand, the acquisition of low-carbon park operation data such as voltage, current, phase angle and the like which are strongly related to time needs to meet the requirement of acquiring time consistency so as to ensure the accuracy of line fault distance measurement, phasor and power angle dynamic monitoring and unit and power grid parameter verification. On the other hand, various power services also need to be carried out at the same time scale, and the asynchronous time can lead to inconsistent service response time of each energy main body of the park group, so that the low-carbon intelligent park group is subjected to asynchronous oscillation and asynchronous operation, and the overall safety of the park group is further influenced. According to the existing Beidou satellite time service method, a satellite positioning module and a satellite receiving antenna are required to be installed on each monitoring terminal and each electrical device, so that the cost is high, and the construction is inconvenient. In addition, satellite time service is easily influenced by external factors, and the time synchronization stability is poor. The time service precision of 5G and optical fiber time service modes is high, but the 5G transmission distance is short, a large number of high-power consumption 5G base stations need to be deployed for realizing wide-area time synchronization, and the high optical fiber construction cost is not beneficial to time synchronization of large-scale low-carbon smart park groups. Therefore, a low-cost and wide-coverage time synchronization method for supporting safe and stable operation of low-carbon intelligent campus groups is needed.
The power line carrier can realize low-cost wide-coverage time synchronization. The power line carrier transmits time service information by using the existing power line, no additional network needs to be erected, the deployment cost is low, the coverage range is wide, and the time synchronization can be realized by connecting the monitoring terminal and the power equipment with the power line. The time synchronization method of the low-carbon intelligent park group by utilizing the power line carrier is divided into two steps, firstly, the low-carbon intelligent park gateways collect accurate time service information through clock sources such as satellites, 5G and optical fibers, and time synchronization among different gateways of the park group is realized. And secondly, the park gateway sends a time service signal through a power line carrier, so that the wide coverage time synchronization of the monitoring terminal and the electrical equipment in the park is realized. However, the existing power line carrier time service method faces the problems of poor campus topology sensing capability, large time delay of time service data packets, large time service error and the like. The specific introduction is as follows:
firstly, the topological structure of the monitoring terminal is complex and changeable due to frequent switching of electrical equipment of the low-carbon intelligent park group, and the existing topological prediction method carries out topological prediction by sending a path search signal through a gateway and analyzing feedback path information. Under the conditions of complex environment of a park and frequent change of the topological structure of the park, the problems of long path searching time and poor topological prediction precision exist, and further time delay and high expense are caused.
Secondly, the time service precision of the sending end of the time service power line carrier data packet in the low-carbon smart park is different, and the channel characteristics such as electromagnetic interference and path gain between the sending end and the receiving end are dynamically changed, so that the path selection of the time service data packet is difficult to optimize. In addition, because some data packet receiving ends and the time service data packet sending ends do not have available paths or have poor path conditions, multi-hop transmission is needed to obtain the data packets, which increases the complexity of optimizing the path selection of the time service data packets, and causes large time service delay and large errors.
Thirdly, the indexes for measuring the time service performance comprise time service delay, time service error, data packet transmission reliability and the like, and all the performance indexes are mutually restricted. For example, the time service errors of some time service data packet sending terminals in the low-carbon intelligent park are small, but the channel conditions between the time service data packet sending terminals and the monitoring terminals to be time-serviced are poor, and the problems of large time service delay, high packet loss rate and the like can be caused when the time service sending terminals are used for time service. Therefore, how to achieve the trade-off between multiple performance indicators is also a problem.
The technical scheme of the prior art I is as follows:
a topology prediction method based on power line carriers;
the first prior art has the following defects:
in the prior art, a large amount of path information between power line carrier signal measurement monitoring terminals needs to be sent, and the path information is analyzed, so that network topology is predicted, a large amount of network resources are wasted, topology prediction time is seriously prolonged, rapid change of a low-carbon intelligent park group topology structure is difficult to adapt, and the real-time requirement of topology prediction cannot be met.
The second technical scheme in the prior art:
a time synchronization method based on power line carrier;
the second prior art has the following defects:
in the second prior art, a transmit end is selected for each receive end aiming at maximizing the signal-to-interference-and-noise ratio to optimize a power line carrier time service path selection strategy, and joint optimization of multiple indexes such as differentiated time service errors and time service time delays of the transmit end is not considered, so that the time service precision of the receive end is seriously reduced by the whole time service performance, and high-precision time synchronization under a complex environment of a low-carbon smart park group cannot be guaranteed.
Disclosure of Invention
The invention aims to solve the technical problems in the background art and provide a low-carbon park group topology prediction and time service method and system based on power line carriers. Based on the topological adjacency relation of the monitoring terminals, a synchronous group game is adopted to optimize the route selection decision of the time service data packet, and the time service is further carried out on the monitoring terminals and the electrical equipment in the garden through power line carriers, so that the high-precision low-delay wide-coverage time synchronization of the low-carbon intelligent garden community is realized.
In order to solve the technical problem, the technical scheme of the invention is as follows:
a low-carbon park group topology prediction and time service method based on power line carriers comprises the following steps:
constructing a power line carrier time service system model by analyzing the actual distribution conditions and accurate time service information data packets of intelligent gateways and monitoring terminals in the intelligent park group;
based on a power line carrier time service system model, under the constraint of signal-to-interference-and-noise ratio, an optimization problem is constructed by optimizing a path selection strategy of a power line carrier time service data packet;
acquiring historical topology information and power line carrier real-time monitoring data stored in a low-carbon smart park database, and predicting the topology condition of a monitoring terminal to obtain the topological adjacency relation of the monitoring terminal;
based on the signal-to-interference-and-noise ratios among monitoring terminals in the power line carrier real-time monitoring data, the topological adjacency relation of the monitoring terminals and the constructed optimization problem, the decision of the time service information data packet path is optimized by utilizing a synchronous set game algorithm to obtain an optimal time service decision result, and the time synchronization of the park group monitoring terminals and the electrical equipment is realized by the decision result.
Further, analysis intelligent gateway and monitor terminal's actual distribution situation and accurate time service information data package in the wisdom garden crowd specifically do:
analyzing the actual distribution condition of intelligent gateways and monitoring terminals in the intelligent park group, determining a set and representing the set as S = { S = { S 0 ,s 1 ,...,s i ,...,s I In which s 0 Representing an intelligent gateway, s 1 ，s i And s I Respectively representing the 1 st, I th and I th monitoring terminals; if the connection topology of monitoring terminals of the park is unknown, the R round time service process is considered together, a set is determined and represented as R = { 1., R., R }, wherein 1, R and R respectively represent the 1 st, R and R round time service;
analyzing the accurate time service information data packet and determining s i In order to be the sender of the data packet,
a data packet receiving end; binary variable for packet routing indicator variable
It is shown that there is, among others,
indicating the r-th round of time service
From s i Receive data packet, otherwise
Determining binary variables
Indicating variables for the topological connection between the intelligent gateway and each monitoring terminal
Denotes s i And
connect otherwise
Further, the power line carrier time service system model comprises: the system comprises a power line carrier time service data packet transmission model, a time service delay model and an accumulated time service error model;
constructing a power line carrier time service data packet transmission model, which specifically comprises the following steps:
the complex electromagnetic environment and noise interference of the low-carbon smart park are considered, the transmission of power line carrier time service data packets and the r-th round time service are realized based on the orthogonal frequency division multiplexing technology
From s i The rate at which packets are received is:
wherein N is s For the transmission rate of the OFDM symbols,
in order to transmit the power, the power is transmitted,
represents the path gain; wherein,
and sigma 0 Path frequency response, electromagnetic interference and Gaussian white noise power;
the signal interference noise ratio gap is expressed, namely the capability of resisting the signal interference noise ratio fading; wherein, P e Representing the target bit error rate, Q -1 (x) To represent
The inverse function of (c).
Constructing the time service delay model; the method specifically comprises the following steps:
dividing each round of time service into a plurality of time slots with the length of tau, and s at the beginning of each time slot i Starting to connect
Transmitting a power line carrier time service data packet; in the multi-hop transmission of the low-carbon intelligent park monitoring terminal topology, the r-th round of time service
The delay of receiving a data packet is determined by the sender s i Delay sum of received data packet
From s i The single-hop transmission delay for receiving a data packet is represented as:
wherein,
denotes s i The number of time slots experienced by the received data packet,
is composed of
From s i The single-hop transmission delay of a received data packet is expressed as:
wherein, U r And the size of the r-th round time service data packet is shown.
The method for constructing the accumulative time service error model specifically comprises the following steps:
determining the r-th wheel
Accumulated time service error of received data packet
Comprises the following steps:
wherein,
time-giving for the r-th round
From s i Receiving the accumulated time service error of the data packet, namely:
wherein,
indicates the r-th round of time service
From s i The single-hop time service error formed by receiving the data packet follows normal distribution with the mean error value of alpha and the standard deviation of beta, i.e.
Time service s for the r-th round i And receiving the accumulated time service error of the data packet.
Further, the optimization target is to minimize the weighted sum of the average time delay and the time service error of each round by optimizing the path selection strategy of the power line carrier time service data packet under the constraint of the signal-to-interference-and-noise ratio, and the optimization problem is specifically constructed as follows:
wherein, χ is a weight parameter used for dynamically balancing time delay and time error; c1 and C2 are path selection constraints and represent each round of time service receiving end
At most, data packets can be received from one transmitting end; c3 represents
And s i When the device is not connected to the power supply,
cannot be obtained from s i Receiving a data packet; in order to ensure the transmission quality of the power line carrier time service data packet, the signal-to-interference-and-noise ratio of the path is constrained, namely C4:
further, the predicting the topology condition of the monitoring terminal specifically includes:
selecting a time service path for the accurate time service information data packet based on the topological adjacency relation of the monitoring terminal;
inputting the historical topology information into a preset BP neural network for pre-training to obtain a trained BP neural network model;
and inputting the real-time monitoring data of the power line carrier into the trained BP neural network model based on the constructed power line carrier time service system model to obtain the topological adjacency relation of the monitoring terminal.
Further, the inputting the historical topology information into a preset BP neural network for pre-training specifically includes:
inputting a park monitoring terminal topological adjacency matrix, topological characteristic data, historical power line carrier time delay and historical power line carrier time error stored in a low-carbon intelligent park database into a preset BP neural network for pre-training;
the preset BP neural network is specifically constructed as follows:
the BP neural network comprises an input layer, a hidden layer and an output layer, the number of neurons of the input layer is X, the number of neurons of each layer of the hidden layer is Y, and the number of neurons of the output layer is Z;
the hidden layer parameters are Q (A, B), Q is a BP neural network parameter matrix, A is a hidden layer weight matrix, and B is a threshold matrix;
an input signal matrix of a BP neural network input layer suitable for topology prediction of a monitoring terminal is represented as follows:
wherein,
respectively representing input signals of 1 st, X and X input layer neurons;
expressing the activation function of the BP neural network as:
wherein κ is an activation function parameter; the BP neural network hidden layer function suitable for the topology prediction of the monitoring terminal is as follows:
wherein,
as weights between input layer neurons and hidden layer neurons, b y To hide the layer threshold, N y Outputting for the y-th neuron of the hidden layer;
the BP neural network output layer function suitable for the topology prediction of the monitoring terminal is as follows:
wherein,
as weights between hidden layer neurons and output layer neurons, c z As output layer threshold, G z Output for the z-th neuron;
expressing the loss function of the BP neural network as:
wherein M is the number of samples, k is the neural network training sample output, k * Period of time ofExpecting to output, wherein m is the dimension of the data; updating the weight according to the negative gradient direction of the error; after an input signal matrix and expected output are given, iteration is repeatedly carried out on each input signal matrix, when all input signal matrix data are repeatedly iterated in sequence, and after sample training is finished, whether the index function meets the precision or not is judged; and stopping training if the index function meets the precision, or retraining until the precision is met, and obtaining the trained BP neural network model suitable for the topology prediction of the monitoring terminal.
Further, the inputting the real-time monitoring data of the power line carrier into the trained BP neural network model to obtain the topological adjacency relationship of the monitoring terminal specifically includes:
when each round of time service process starts, inputting real-time monitoring data of power line carriers among the monitoring terminals into a trained BP neural network model to obtain the topological connection relation of the monitoring terminals in the current round of time service; topological adjacency matrix W of monitoring terminal r Can be represented by the following formula:
further, before optimizing the decision of the time service information data packet path by using a synchronous group game algorithm, the method further comprises the following steps:
firstly, in the r round of time service, a power line carrier time service data packet sending end and a plurality of time service data packet receiving ends are defined as a multi-path broadcast group which is marked as
The utility function of (a) can be represented by:
wherein,
is composed of
The number of the receiving ends of the medium data packet;
defining the synchronous group Game of the r-th round time service as Game r (Φ r V), wherein phi represents the set of monitoring terminals participating in the game, and the game is satisfied
V represents the value of the synchronization group, defined as:
in each synchronization group, whether the synchronization group allows the data packet receiving end to add depends on the contribution of the synchronization group to the value of the synchronization group, and if the receiving end seriously increases the average time delay and time error of the multi-path broadcast group, the data packet receiving end is rejected; therefore, the receiving end in the r-th round time service synchronization group
Gain of (2)
Is defined as the contribution to the value of the synchronization group, calculated as:
wherein,
to represent
Joining a Sync group
Further, the decision of the time service information data packet path is optimized by using a synchronous group game algorithm, which specifically comprises the following steps:
step 1: and (3) initializing a synchronization group:
calculating the priority of each receiving end to all sending ends receiving the time service information data packets according to the SINR and the topological adjacency relation among the monitoring terminals, wherein the preference sequence is arranged in a descending order according to the SINR; for the receiving end
If present, satisfy
The sender of (2), then add it to the set
At the same time, the user can select the desired position,
in
Temporarily joining a synchrony group
Wherein s is i In the priority order of first; if the receiving end
Is not satisfied with any transmitting end
Then the receiving end
Does not participate in the current round of time service;
and 2, step: establishing a synchronization group:
when all the synchronization groups of the time slot are temporarily established, the receiving end, for example
According to the formula
The calculated income, namely the optimization target, is selected to join other synchronization groups; if it is not
Then
Selecting away from a current synchronization group
To join the synchronization group
The receiving end in the system can continuously select and replace the synchronous group according to the income until no receiving end selects and replaces the synchronous group;
and step 3: and finally, establishing a synchronization group and transmitting a power line carrier time service data packet:
repeating the step 2 until all receiving ends do not change the selection; the time when the synchronization group is finally formed is called a decision point; after that, the sending end in each synchronization group starts to transmit the power line carrier timing data packet in the same synchronization group; after each sending end in all the synchronous groups completes time service, the synchronous groups of the time slot are dispersed;
and 4, step 4: and the next time slot transmission:
at the end of each time slot, checking whether all synchronization groups complete transmission; then, a receiving end which receives the power line carrier time service data packet in the current time slot is used as a sending end for the next time slot transmission; the algorithm is transferred to step 1; and when each monitoring terminal completes time service, the current round of time service is finished.
Low carbon garden group topology prediction and time service system based on power line carrier, the system is applied to the control layer, the system includes:
the first construction module is used for constructing a power line carrier time service system model by analyzing the actual distribution conditions and the accurate time service information data packets of the intelligent gateways and the monitoring terminals in the intelligent park group;
the second construction module is used for constructing an optimization problem by optimizing a path selection strategy of a power line carrier time service data packet under the constraint of a signal-to-interference-and-noise ratio based on a power line carrier time service system model;
the topology prediction module is used for acquiring historical topology information and power line carrier real-time monitoring data stored in the low-carbon intelligent park database, predicting the topology condition of the monitoring terminal and obtaining the topological adjacent relation of the monitoring terminal;
and the decision optimization module is used for optimizing the decision of the time service information data packet path by utilizing a synchronous set game algorithm based on the signal-to-interference-and-noise ratio among the monitoring terminals, the topological adjacency relation of the monitoring terminals and the constructed optimization problem in the power line carrier real-time monitoring data to obtain an optimal time service decision result, and the decision result realizes the time synchronization of the park group monitoring terminals and the electrical equipment.
Further, the first building block includes: an analysis unit and a first construction unit;
the analysis unit is used for determining that one intelligent gateway and I monitoring terminals exist in the park, and determining a set represented by S = { S = (S) = 0 ,s 1 ,...,s i ,...,s I In which s is 0 Representing an intelligent gateway, s 1 ，s i And s I Respectively representing the 1 st, I th and I th monitoring terminals; if the connection topology of monitoring terminals of the park is unknown, the R round time service process is considered together, a set is determined and represented as R = { 1., R., R }, wherein 1, R and R respectively represent the 1 st, R and R round time service;
determining s i In order to be the sender of the data packet,
a data packet receiving end; binary variable for packet routing indicator variable
It is shown that, among others,
indicating the r-th round of time service
From s i Receive data packet, otherwise
Determining binary variables
Indicating variables for the topological connection between the intelligent gateway and each monitoring terminal
Denotes s i And
connect otherwise
Further, the first constructing unit is configured to construct the power line carrier time service data packet transmission model, and specifically includes:
the complex electromagnetic environment and noise interference of the low-carbon smart park are considered, the transmission of power line carrier time service data packets and the r-th round time service are realized based on the orthogonal frequency division multiplexing technology
From s i The rate at which packets are received is:
wherein N is s For the transmission rate of the OFDM symbols,
in order to transmit the power, the power is transmitted,
represents the path gain; wherein,
and sigma 0 Path frequency response, electromagnetic interference and Gaussian white noise power;
the signal interference noise ratio gap is expressed, namely the capability of resisting the signal interference noise ratio fading; wherein, P e Representing the target bit error rate, Q -1 (x) To represent
The inverse function of (c).
The time delay model is used for constructing the time delay model; the method specifically comprises the following steps:
dividing each round of time service into a plurality of time slots with the length of tau, and s at the beginning of each time slot i Starting to connect
Transmitting a power line carrier time service data packet; in the multi-hop transmission of the low-carbon intelligent park monitoring terminal topology, the r-th round of time service
The delay of receiving a data packet is determined by the sender s i Delay sum of received data packet
From s i The single-hop transmission delay for receiving a data packet is represented as:
wherein,
denotes s i The number of time slots experienced by the received data packet,
is composed of
From s i The single-hop transmission delay of a received data packet is expressed as:
wherein, U r And the size of the r-th round time service data packet is shown.
The method is used for constructing the accumulated time service error model and specifically comprises the following steps:
determining the r-th wheel
Accumulated time service error of received data packet
Comprises the following steps:
wherein,
time-giving for the r-th round
From s i Receiving the accumulated time service error of the data packet, namely:
wherein,
indicating the r-th round of time service
From s i The single-hop time service error formed by receiving the data packet follows normal distribution with the mean error value of alpha and the standard deviation of beta, i.e.
Time service s for the r-th round i And receiving the accumulated time service error of the data packet.
Further, the second building block includes: constructing an optimization problem unit;
the optimization problem unit is used for minimizing the weighted sum of the average time delay and the time service error of each round under the constraint of the signal-to-interference-and-noise ratio by optimizing the path selection strategy of the power line carrier time service data packet, and the optimization problem is specifically constructed as follows:
wherein, χ is a weight parameter used for dynamically balancing time delay and time error; c1 and C2 are path selection constraints and represent each round of teachingTime receiving terminal
At most, data packets can be received from one transmitting end; c3 represents
And s i When the device is not connected to the power source,
cannot be obtained from s i Receiving a data packet; in order to ensure the transmission quality of the power line carrier time service data packet, the signal-to-interference-and-noise ratio of the path is constrained, namely C4:
further, the topology prediction module includes:
the monitoring unit is used for selecting a time service path for the accurate time service information data packet based on the topological adjacency relation of the monitoring terminal;
the pre-training unit is used for inputting the historical topology information into a preset BP neural network for pre-training to obtain a trained BP neural network model;
the inputting of the historical topology information into a preset BP neural network for pre-training specifically includes:
inputting a park monitoring terminal topological adjacency matrix, topological characteristic data, historical power line carrier time delay and historical power line carrier time error stored in a low-carbon intelligent park database into a preset BP neural network for pre-training;
the preset BP neural network is specifically constructed as follows:
the BP neural network comprises an input layer, a hidden layer and an output layer, the number of neurons of the input layer is X, the number of neurons of each layer of the hidden layer is Y, and the number of neurons of the output layer is Z;
the hidden layer parameters are Q (A, B), Q is a BP neural network parameter matrix, A is a hidden layer weight matrix, and B is a threshold matrix;
an input signal matrix of a BP neural network input layer suitable for topology prediction of a monitoring terminal is represented as follows:
wherein,
respectively representing input signals of 1 st, X and X input layer neurons;
expressing the activation function of the BP neural network as:
wherein κ is an activation function parameter; the BP neural network hidden layer function suitable for the topology prediction of the monitoring terminal is as follows:
wherein,
as weights between input layer neurons and hidden layer neurons, b y To hide the layer threshold, N y Outputting for the y-th neuron of the hidden layer;
the BP neural network output layer function suitable for the topology prediction of the monitoring terminal is as follows:
wherein,
as weights between hidden layer neurons and output layer neurons, c z As output layer threshold, G z Output for the z-th neuron;
expressing the loss function of the BP neural network as:
wherein M is the number of samples, k is the neural network training sample output, k * M is the dimensionality of the data for the desired output; updating the weight according to the negative gradient direction of the error; after an input signal matrix and expected output are given, iteration is repeatedly carried out on each input signal matrix, when all input signal matrix data are repeatedly iterated in sequence, and after sample training is finished, whether the index function meets the precision or not is judged; stopping training if the index function meets the precision, or else, retraining until the precision is met, and obtaining a trained BP neural network model suitable for the topology prediction of the monitoring terminal;
the solving unit is used for inputting real-time monitoring data of the power line carrier into the trained BP neural network model based on the constructed power line carrier time service system model to obtain the topological adjacency relation of the monitoring terminal;
the method for inputting the real-time monitoring data of the power line carrier into the trained BP neural network model to obtain the topological adjacency relation of the monitoring terminal specifically comprises the following steps:
when each round of time service process starts, inputting real-time monitoring data of power line carriers among the monitoring terminals into a trained BP neural network model to obtain the topological connection relation of the monitoring terminals in the current round of time service; topological adjacency matrix W of monitoring terminal r Can be represented by the following formula:
further, the decision optimization module includes:
synchronization group initialization unit: for monitoring signal-to-interference-and-noise ratio between terminals and topological adjacent relationThe priority sequence of each receiving end to all sending ends receiving time service information data packets is calculated, and the preference sequence is arranged according to the signal to interference plus noise ratio in a descending order; for the receiving end
If present, satisfy
The sending end of (2), then add it to the set
At the same time, the user can select the desired position,
in (1)
Temporarily joining a synchrony group
Wherein s is i In the priority order of first; if the receiving end
Is not satisfied with any transmitting end
Then the receiving end
Does not participate in the current round of time service;
establishing a synchronous group unit: for the receiving end, e.g. after all the synchronization groups of the time slot have been temporarily established
According to the formula
The calculated benefits, namely the optimization targets, are selected to join other synchronization groups; if it is not
Then the
Selecting away from a current synchronization group
To join the synchronization group
The receiving end in the system can continuously select and replace the synchronous group according to the income until no receiving end selects and replaces the synchronous group;
and the transmission establishing unit is used for establishing a final synchronization group and transmitting a power line carrier time service data packet: the method specifically comprises the following steps:
repeating the processing method for establishing the synchronous group unit until all receiving ends do not change the selection; the time when the synchronization group is finally formed is called a decision point; after that, the sending end in each synchronization group starts to transmit the power line carrier timing data packet in the same synchronization group; after each sending end in all the synchronous groups completes time service, the synchronous groups of the time slot are dispersed;
a detecting unit for checking whether all the synchronization groups complete transmission at the end of each time slot; then, a receiving end which receives the power line carrier time service data packet in the current time slot is used as a sending end for the next time slot transmission; transferring the algorithm into a synchronization group initialization unit; and when each monitoring terminal completes time service, the current round of time service is finished.
A computer readable storage medium having stored therein computer executable instructions for performing the method of any one of the above when executed by a processor.
Compared with the prior art, the invention has the advantages that:
1) The invention provides a low-carbon intelligent park group topology prediction and time service system based on power line carriers. Under the drive of the control layer, the low-carbon intelligent park group power line carrier intelligent gateway selects time service information transmitted by the Beidou satellite, the 5G and the optical fiber time synchronization network, and realizes the time synchronization of the low-carbon intelligent park group intelligent gateway; secondly, the intelligent gateway executes the provided high-precision low-delay topology prediction and time service method based on the power line carrier, senses the topology structure of the park on line, and performs time service for the monitoring terminals and the electrical equipment in the park through the path optimization of the power line carrier time service data packet, so that the low-cost wide-coverage time synchronization of the low-carbon intelligent park group monitoring terminal layer is realized.
2) The invention establishes a time delay and time error weighting and minimum path selection optimization model based on signal-to-interference-and-noise ratio constraints, guarantees the transmission reliability of a time service data packet through the signal-to-interference-and-noise ratio constraints, adjusts and optimizes the target weight according to the actual conditions of a low-carbon intelligent park, realizes dynamic balance of time delay and time service error performance, meets the time service requirements of different low-carbon intelligent park groups, and supports efficient and stable operation of services such as flexible load regulation and control of park groups, carbon footprint monitoring, electric power spot market transaction and the like under the same time scale.
3) The invention provides a high-precision low-delay topology prediction and time service method based on a power line carrier. Firstly, historical topology information stored in a low-carbon intelligent park group database is introduced, a mapping relation between a monitoring terminal topology adjacency relation matrix and input data is fitted, and a BP neural network model for topology prediction is trained. When each round of time service process starts, power line carrier monitoring data such as signal-to-interference-and-noise ratio, electromagnetic interference and the like among the monitoring terminals are input into a training model, the topological adjacent relation of the monitoring terminals is sensed on line, and the reliable, real-time and low-cost prediction of the topological structure of the intelligent park monitoring terminal is realized. Secondly, each round of time service is based on a predicted topological structure, and a synchronous group transmission time service data packet is formed by taking the weighted sum of the minimum average time service delay and the time service error as a target under the constraint of the signal-to-interference-and-noise ratio, so that the high-precision low-delay time synchronization under the complex environment of the low-carbon intelligent park group is ensured.
Drawings
FIG. 1 is a diagram of a low-carbon intelligent park group topology prediction and time service system based on power line carriers;
FIG. 2 is a schematic diagram of a low-carbon smart park group power line carrier sensing topology prediction method;
FIG. 3 is a flow chart of a low-carbon intelligent park group power line carrier time service method based on a synchronous group game.
Detailed Description
The following describes embodiments of the present invention with reference to examples:
it should be noted that the structures, proportions, sizes, and other elements shown in the specification are included for the purpose of understanding and reading only, and are not intended to limit the scope of the invention, which is defined by the claims, and any modifications of the structures, changes in the proportions and adjustments of the sizes, without affecting the efficacy and attainment of the same.
In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are used for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms may be changed or adjusted without substantial change in the technical content.
Example 1:
as shown in fig. 1, the topology prediction and time service system for a low-carbon smart park community includes a clock source layer, a gateway layer, a terminal layer and a control layer. The clock source layer provides standard time information for the gateway layer by using the Beidou satellite, the 5G and the optical fiber time synchronization network. The gateway layer is composed of low-carbon intelligent park group intelligent gateways, local clock calibration is carried out by receiving time service information from a clock source layer, a power line carrier time service data packet is sent to the low-carbon intelligent park group monitoring terminals of the terminal layer in a multicast mode, and time synchronization of the monitoring terminals in the park and electrical equipment is guaranteed. The terminal layer provides various electrical equipment information such as carbon emission, voltage, current, active/reactive power, charge and discharge power and the like for the gateway layer by deploying low-carbon intelligent park monitoring terminals on electrical equipment such as a photovoltaic panel, a wind turbine generator, an electric automobile charging pile and the like, and feeds back the time service error and the time service delay of the time service data packet to the control layer to optimize a time service data packet path selection strategy. In addition, the low-carbon intelligent park monitoring terminal conducts low-carbon intelligent park group distributed resource regulation and control by forwarding power business instructions such as flexible load regulation and control, carbon footprint monitoring, power spot market trading and the like issued by the load aggregator and the power grid dispatching center. The control layer deployment is suitable for functions of topology prediction of the low-carbon intelligent park group, power line time service data packet path selection optimization and the like, and the distributed resource regulation and control of the low-carbon intelligent park group are guaranteed to be carried out on the same time scale.
The control layer interacts with each layer to complete low-cost wide-coverage time synchronization of the low-carbon intelligent park group. The control layer dynamically adjusts the broadcasting frequency of the Beidou satellite, the 5G and the optical fiber time service signals based on the link quality of each clock source through interaction with the clock source layer. The control layer selects a proper time signal for the intelligent low-carbon intelligent park gateway by interacting with the gateway layer and combining the time service precision of each clock source of the clock source layer, and standard time information is obtained. The control layer interacts with the terminal layer to construct a low-carbon intelligent park group database, a terminal topology adjacency matrix is established based on neural network comprehensive analysis, topology prediction is achieved, a path selection strategy of a power line carrier time service data packet is optimized based on a synchronous set game according to feedback time service time delay and time service errors, time synchronization of park group monitoring terminals and electrical equipment is achieved, and distributed resource regulation and control consistency response of the low-carbon intelligent park group is guaranteed.
High-precision low-delay topology prediction and time service method based on power line carrier
The invention designs a high-precision low-delay topology prediction and time service method based on power line carriers for a low-carbon intelligent park group, which mainly comprises four stages of power line carrier time service model construction, problem optimization modeling, a low-carbon intelligent park group power line carrier sensing topology prediction method and a low-carbon intelligent park group power line carrier time service method based on synchronous group game, and specifically introduces the following steps:
(1) Power line carrier time service model construction
The invention relates to a scene that a low-carbon intelligent park group intelligent gateway issues a power line carrier time service data packet to carry out time service on monitoring terminals in a park on the basis of obtaining accurate time service information through a satellite, a 5G and an optical fiber time synchronization network. Suppose there are one intelligent gateway and I monitoring terminals in a campus, the set is denoted as S = { S = { S } 0 ,s 1 ,...,s i ,...,s I In which s is 0 Representing an intelligent gateway, s 1 ，s i And s I Respectively representing the 1 st, I terminal. It is assumed that the terminal connection topology of the campus is unknown. Considering the R round timing process together, the set is represented as R = { 1., R }, where 1, R, and R represent the 1 st, R, and R round timing, respectively. And the intelligent gateway and the terminal are communicated through a power line carrier. And each round of time service starts from the intelligent gateway to send a power line carrier time service data packet, and ends when all terminals in the park receive the time service data packet, wherein the time length of each round of time service is equal to the time when the last terminal receives the time service data packet. In each round of time service, the intelligent gateway sends the time service data packet to the terminals, the terminals which receive the time service data packet firstly complete time synchronization, then the terminals are converted into new sending terminals to distribute the time service data packet to the terminals which do not receive the data packet until all the terminals receive the time service data packet, and particularly, the intelligent gateway can only be used as a data packet sending terminal.
Definition s i In order to be the sender of the data packet,
is the data packet receiving end. Binary variable for packet routing indicator variable
It is shown that, among others,
in the r-th round of time service
From s i Receive data packet, otherwise
Defining binary variables
Variables are indicated for the intelligent gateway and the topological connections between the terminals,
denotes s i And
connect otherwise
A time service data packet transmission model, a time service delay model and an accumulated time service error model are considered, which are described in detail below.
1) Power line carrier time service data packet transmission model
In consideration of complex electromagnetic environment and noise interference of a low-carbon smart park, the invention realizes transmission of power line carrier time service data packets based on Orthogonal Frequency Division Multiplexing (OFDM). Time service of r-th round
From s i The rate at which packets are received is:
wherein N is s For the transmission rate of the OFDM symbols,
in order to transmit the power, the power is transmitted,
showing roadAnd (4) path gain. Wherein,
and sigma 0 Path frequency response, electromagnetic interference, and gaussian white noise power, respectively.
Indicating the sir gap, i.e., the ability to resist sir fading. Wherein, P e Representing the target bit error rate, Q -1 (x) To represent
The inverse function of (c).
In order to ensure the transmission quality of the power line carrier time service data packet, the invention makes constraint on the signal-to-interference-and-noise ratio of the path, namely:
2) Time service delay model
The invention divides each round of time service into a plurality of time slots with length of tau, and s is the beginning of each time slot i Starting to connect
And transmitting the power line carrier timing data packet. In multi-hop transmission of low-carbon intelligent park terminal topology, the r-th round of time service
The delay of receiving a data packet is determined by the sender s i Delay sum of received data packet
From s i The single-hop transmission delay of the received data packet is composed of two parts, which are expressed as
Wherein,
denotes s i The number of time slots experienced by the received data packet,
is composed of
From s i The single-hop transmission delay of a received data packet is expressed as:
wherein, U r And the size of the r-th round time service data packet is shown.
3) Accumulated time service error model
Define the r-th wheel
The accumulated time service error of the received data packet is
Is shown as
Wherein,
time-giving for the r-th round
From s i Accumulated time error of received data packets, i.e.
Wherein,
indicating the r-th round of time service
From s i Receiving a single-hop time service error formed by a data packet, and following normal distribution with the average error value of alpha and the standard deviation of beta, namely
Time service s for the r-th round i Accumulated time service error of received data packet
(2) Optimization problem modeling
The optimization objective of the invention is to minimize the weighted sum of the average time delay and time service error of each round by optimizing the path selection strategy of the power line carrier time service data packet under the constraint of the signal-to-interference-and-noise ratio, and the optimization problem can be modeled as
And x is a weight parameter used for dynamically balancing the time delay and the time error. C1 and C2 are path selection constraints and represent each round of time service receiving end
At most, data packets can be received from one transmitting end. C3 represents
And s i When the device is not connected to the power supply,
cannot be obtained from s i A data packet is received. C4 is the signal to interference plus noise ratio constraint.
(3) Low-carbon smart park group power line carrier sensing topology prediction method
In order to realize high-precision low-delay time service of the low-carbon intelligent park group terminal, the topological situation of the park group terminal needs to be accurately predicted to obtain a topological adjacency relation matrix. Based on the method, historical topology information stored in a low-carbon intelligent park database is input into a neural network for pre-training. And inputting real-time power line carrier monitoring data such as signal-to-interference-and-noise ratio, electromagnetic interference and the like into the trained BP neural network, and sensing the topological adjacency relation of the terminal to realize accurate topological prediction. A schematic diagram of a low-carbon smart campus power line carrier sensing topology prediction method is shown in fig. 2, and the method includes the following steps:
step 1: BP neural network construction and pre-training
The invention inputs the park terminal topology adjacency relation matrix, the characteristic data between topologies such as signal-to-interference-and-noise ratio and electromagnetic interference, and historical time delay and error data stored in the low-carbon intelligent park database into a neural network for pre-training, and realizes topology prediction by comprehensively analyzing, fitting and adapting to relevant parameters of park topology prediction. The neural network model is constructed as follows:
the BP neural network comprises an input layer, a hidden layer and an output layer, the number of neurons of the input layer is X, the number of neurons of each layer of the hidden layer is Y, and the number of neurons of the output layer is Z. The hidden layer parameters are Q (A, B), Q is a BP neural network parameter matrix, A is a hidden layer weight matrix, and B is a threshold matrix.
The input signal matrix of the BP neural network input layer suitable for terminal topology prediction can be represented by the following formula:
wherein,
representing the input signals of 1 st, X input layer neurons, respectively. Thus, of BP neural networksThe activation function is expressed as
Where κ is an activation function parameter. The hidden layer function of the BP neural network suitable for terminal topology prediction is
Wherein
As weights between input layer neurons and hidden layer neurons, b y To hide the layer threshold, N y Is output for the y-th neuron of the hidden layer. BP neural network output layer function suitable for terminal topology prediction is
Wherein,
as weights between hidden layer neurons and output layer neurons, c z As output layer threshold, G z Is output for the z-th neuron.
In the pre-training process, errors are generated in each training, the loss function can reflect the difference between the model and actual data, the errors are gradually reduced in the next training through back propagation updating weight and bias, and the prediction precision is improved. To determine the error between the estimated value and the actual value, a loss function is defined
Wherein M is the number of samples, k is the neural network training sample output, k * To a desired outputAnd m is the dimension of the data. And updating the weight according to the direction of the negative gradient of the error. And after the input samples and the expected output are given, iterating each input sample repeatedly, and after all the input sample data are iterated in sequence and the sample training is finished, judging whether the index function meets the precision. And if the index function meets the precision, stopping training, otherwise, retraining until the precision is met.
Step 2: terminal topology adjacency matrix prediction
After a BP neural network model suitable for terminal topology prediction is obtained according to the process, when each round of time service process starts, power line carrier monitoring data such as signal-to-interference-and-noise ratio, electromagnetic interference and the like between terminals are input into the trained BP neural network model, and the terminal topology connection relation of the round of time service is obtained through the mapping relation between the terminal topology adjacency relation matrix fitted in the pre-training process and the input data. Terminal topological adjacency matrix W r Can be represented by the following formula:
(4) Low-carbon intelligent park group power line carrier time service method based on synchronous group game
Obtaining a terminal topological adjacency relation matrix W r Then, the invention provides a low-carbon intelligent park group power line carrier time service method based on synchronous group game to optimize power line carrier time service data packet path selection decision. In the r round of time service, a power line carrier time service data packet sending end and a plurality of time service data packet receiving ends are defined as a multi-path broadcast group which is marked as
The utility function of (a) can be represented by:
wherein,
is composed of
The number of receiving ends of the medium data packet.
Because the time service data packets of terminals in the park are transmitted through the multi-path broadcast groups, the optimization problem can be expressed as a synchronous group game problem, each multi-path broadcast group forms a synchronous group, each terminal serving as a player tends to join the synchronous group to receive the data packets so as to reduce the time service time delay and the time service error of the terminal, and the average time delay and the error of the receiving end of the data packets in the group are not increased. The invention defines the synchronous group Game of the r-th round time service as Game r (Φ r V), where phi denotes the set of terminals participating in the game, satisfies
V represents the value of the synchronization group, defined as:
in each synchronization group, whether the synchronization group allows the data packet receiving end to join depends on the contribution of the synchronization group to the value of the synchronization group, and if the receiving end seriously increases the average time delay and time error of the multi-path broadcast group, the receiving end is rejected. Therefore, the receiving end in the r-th round time service synchronization group
Gain of (2)
Is defined as the contribution to the value of the synchronization group, calculated as:
wherein,
to represent
Joining a Sync group
To solve the above problem of the synchronous group game, a synchronous group forming algorithm is adopted herein, and a flow chart is shown in fig. 3, which is specifically described as follows:
step 1: sync group initialization
And calculating the priority of each receiving end to all the transmitting ends according to the SINR between the terminals and the topological adjacency relation matrix, and arranging the preference sequence in a descending order according to the SINR. For the receiving end
If there is a sender that satisfies equation (2), it is added to the set
At the same time, the user can select the desired position,
in (1)
Temporarily joining a synchrony group
Wherein s is i In the first priority order. If the receiving end
If the formula (2) is not satisfied with any transmitting end, the receiving end
Does not participate in the current round of time service.
Step 2: establishing a synchronization group
When all the synchronization groups of the time slot are temporarily established, the receiving end, e.g.
The other synchronization groups may be selected for joining based on the benefit calculated by equation (16). If it is not
Then
Selecting from a current synchronization group
To join the synchronization group
The receiving end in (2) can continuously select the replacement synchronization group according to the profit until no receiving end selects the replacement synchronization group.
And step 3: final synchronization group establishment and power line carrier time service data packet transmission
Repeat step 2 until all receivers do not change the selection. The present invention refers to the time at which the synchronization group is ultimately formed as a decision point. After that, the transmitting end in each synchronization group starts to transmit the power line carrier timing data packet in the same synchronization group. And when each sending end in all the synchronous groups completes time service, the synchronous groups of the time slot are dispersed.
And 4, step 4: next time slot transmission
At the end of each slot, the gateway checks whether all synchronization groups have completed transmission. Then, the receiving end receiving the power line carrier timing data packet in the current time slot is used as the transmitting end of the next time slot transmission. The algorithm proceeds to step 1.
And when each terminal completes time service, the time service is finished in the current round.
Example 2:
in order to better implement the above method, the present embodiment provides a low-carbon park group topology prediction and time service system based on power line carriers, where the system includes:
the system is applied to a control layer and comprises:
the first construction module is used for constructing a power line carrier time service system model by analyzing the actual distribution conditions and the accurate time service information data packets of the intelligent gateways and the monitoring terminals in the intelligent park group;
the second construction module is used for constructing an optimization problem by optimizing a path selection strategy of a power line carrier time service data packet under the constraint of a signal-to-interference-and-noise ratio based on a power line carrier time service system model;
the topology prediction module is used for acquiring historical topology information and power line carrier real-time monitoring data stored in the low-carbon intelligent park database, predicting the topology condition of the monitoring terminal and obtaining the topological adjacent relation of the monitoring terminal;
and the decision optimization module is used for optimizing the decision of the time service information data packet path by utilizing a synchronous set game algorithm based on the signal-to-interference-and-noise ratio among the monitoring terminals, the topological adjacency relation of the monitoring terminals and the constructed optimization problem in the power line carrier real-time monitoring data to obtain an optimal time service decision result, and the decision result realizes the time synchronization of the park group monitoring terminals and the electrical equipment.
Further, the first building block includes: an analysis unit and a first construction unit;
the analysis unit is used for determining that one intelligent gateway and I monitoring terminals exist in the park, and determining a set represented by S = { S = (S) = 0 ,s 1 ,...,s i ,...,s I In which s 0 Representing an intelligent gateway, s 1 ，s i And s I Respectively representing the 1 st, I th and I th monitoring terminals; if the connection topology of monitoring terminals of the park is unknown, the R round time service process is considered together, a set is determined and represented as R = { 1., R., R }, wherein 1, R and R respectively represent the 1 st, R and R round time service;
determining s i In order to be the sender of the data packet,
a data packet receiving end; binary variable for packet routing indicator variable
It is shown that, among others,
indicating the r-th round of time service
From s i Receive data packet, otherwise
Determining binary variables
Indicating variables for the topological connection between the intelligent gateway and each monitoring terminal
Denotes s i And
connect otherwise
Further, the first constructing unit is configured to construct the power line carrier time service data packet transmission model, and specifically includes:
the complex electromagnetic environment and noise interference of the low-carbon smart park are considered, the transmission of power line carrier time service data packets and the r-th round time service are realized based on the orthogonal frequency division multiplexing technology
From s i The rate at which packets are received is:
wherein N is s For the transmission rate of the OFDM symbols,
in order to transmit the power, the power is transmitted,
represents the path gain; wherein,
and sigma 0 Path frequency response, electromagnetic interference and Gaussian white noise power;
the signal interference noise ratio gap is expressed, namely the capability of resisting the signal interference noise ratio fading; wherein, P e Representing the target bit error rate, Q -1 (x) Represent
The inverse function of (c).
The time delay model is used for constructing the time delay model; the method specifically comprises the following steps:
dividing each round of time service into a plurality of time slots with the length of tau, and s at the beginning of each time slot i Starting to connect
Transmitting a power line carrier time service data packet; in the multi-hop transmission of the low-carbon intelligent park monitoring terminal topology, the r-th round of time service
The delay of receiving a data packet is determined by the sender s i Delay sum of received data packet
From s i Single-hop transmission delay two-part composition for receiving data packetExpressed as:
wherein,
denotes s i The number of time slots experienced by the received data packet,
is composed of
From s i The single-hop transmission delay of a received data packet is expressed as:
wherein, U r And the size of the r-th round time service data packet is shown.
The method is used for constructing the accumulative time service error model and specifically comprises the following steps:
determining the r-th wheel
Accumulated time service error of received data packet
Comprises the following steps:
wherein,
time-giving for the r-th round
From s i Receiving dataThe accumulated time service error of the packet, namely:
wherein,
indicating the r-th round of time service
From s i The single-hop time service error formed by receiving the data packet follows normal distribution with the mean error value of alpha and the standard deviation of beta, i.e.
Time service s for the r-th round i And receiving the accumulated time service error of the data packet.
Further, the second building block includes: constructing an optimization problem unit;
the optimization problem unit is used for minimizing the weighted sum of the average time delay and the time service error of each round under the constraint of the signal-to-interference-and-noise ratio by optimizing the path selection strategy of the power line carrier time service data packet, and the optimization problem is specifically constructed as follows:
wherein, χ is a weight parameter used for dynamically balancing time delay and time error; c1 and C2 are path selection constraints and represent each round of time service receiving end
At most, data packets can be received from one transmitting end; c3 represents
And s i When the device is not connected to the power supply,
cannot be obtained from s i Receiving a data packet; in order to ensure the transmission quality of the power line carrier time service data packet, the signal-to-interference-and-noise ratio of the path is constrained, namely C4:
further, the topology prediction module includes:
the monitoring unit is used for selecting a time service path for the accurate time service information data packet based on the topological adjacency relation of the monitoring terminal;
the pre-training unit is used for inputting the historical topology information into a preset BP neural network for pre-training to obtain a trained BP neural network model;
the inputting of the historical topology information into a preset BP neural network for pre-training specifically comprises:
inputting a campus monitoring terminal topology adjacency matrix, inter-topology characteristic data, historical power line carrier time delay and historical power line carrier time error stored in a low-carbon intelligent campus database into a preset BP neural network for pre-training;
the preset BP neural network is specifically constructed as follows:
the BP neural network comprises an input layer, a hidden layer and an output layer, wherein the number of neurons of the input layer is X, the number of neurons of each layer of the hidden layer is Y, and the number of neurons of the output layer is Z;
the hidden layer parameters are Q (A, B), Q is a BP neural network parameter matrix, A is a hidden layer weight matrix, and B is a threshold matrix;
an input signal matrix of a BP neural network input layer suitable for topology prediction of a monitoring terminal is represented as follows:
wherein,
respectively representing input signals of 1 st, X and X input layer neurons;
expressing the activation function of the BP neural network as:
wherein κ is an activation function parameter; the BP neural network hidden layer function suitable for the topology prediction of the monitoring terminal is as follows:
wherein,
as weights between input layer neurons and hidden layer neurons, b y To hide the layer threshold, N y Outputting for the y-th neuron of the hidden layer;
the BP neural network output layer function suitable for the topology prediction of the monitoring terminal is as follows:
wherein,
as weights between hidden layer neurons and output layer neurons, c z As output layer threshold, G z Is output for the z-th neuron;
expressing the loss function of the BP neural network as:
wherein M is the number of samples, k is the neural network training sample output, k * M is the dimensionality of the data for the desired output; updating the weight according to the negative gradient direction of the error; after an input signal matrix and expected output are given, iteration is repeatedly carried out on each input signal matrix, when all input signal matrix data are repeatedly iterated in sequence, and after sample training is finished, whether the index function meets the precision or not is judged; stopping training if the index function meets the precision, otherwise, retraining until the precision is met, and obtaining a trained BP neural network model suitable for monitoring terminal topology prediction;
the solving unit is used for inputting real-time monitoring data of the power line carrier into the trained BP neural network model based on the constructed power line carrier time service system model to obtain the topological adjacency relation of the monitoring terminal;
the method for inputting the real-time monitoring data of the power line carrier into the trained BP neural network model to obtain the topological adjacency relation of the monitoring terminal specifically comprises the following steps:
when each round of time service process starts, inputting real-time monitoring data of power line carriers among the monitoring terminals into a trained BP neural network model to obtain the topological connection relation of the monitoring terminals in the current round of time service; topological adjacency matrix W of monitoring terminal r Can be represented by the following formula:
further, the decision optimization module includes:
synchronization group initialization unit: the system comprises a plurality of receiving terminals, a plurality of topology adjacency relations and a plurality of priority orders, wherein the topology adjacency relations are used for calculating the priority order of all the receiving terminals receiving the time service information data packets by each receiving terminal according to the SINR and the topology adjacency relations among the monitoring terminals, and the priority orders are arranged according to the SINR descending order; for the receiving end
If present, satisfy
The sender of (2), then add it to the set
At the same time, the user can select the desired position,
in (1)
Temporarily joining a synchrony group
Wherein s is i The priority order is first; if the receiving end
Is not satisfied with any transmitting end
Then the receiving end
Does not participate in the current round of time service;
establishing a synchronous group unit: for the receiving end, e.g. after all the synchronization groups of the time slot have been temporarily established
According to the formula
The calculated income, namely the optimization target, is selected to join other synchronization groups; if it is not
Then
Selecting away from a current synchronization group
To join the synchronization group
The receiving end in the system can continuously select and replace the synchronous group according to the income until no receiving end selects and replaces the synchronous group;
and the transmission establishing unit is used for establishing a final synchronization group and transmitting a power line carrier time service data packet: the method comprises the following specific steps:
repeating the processing method for establishing the synchronous group unit until all receiving ends do not change the selection; the time when the synchronization group is finally formed is called a decision point; after that, the sending end in each synchronization group starts to transmit the power line carrier timing data packet in the same synchronization group; after each sending end in all the synchronous groups completes time service, the synchronous groups of the time slot are dispersed;
a detecting unit for checking whether all the synchronization groups complete transmission at the end of each time slot; then, a receiving end which receives the power line carrier time service data packet in the current time slot is used as a sending end for the next time slot transmission; transferring the algorithm into a synchronization group initialization unit; when each monitoring terminal completes time service, the current round of time service is finished.
Example 3:
it will be understood by those skilled in the art that all or part of the steps of the methods of the above embodiments may be performed by instructions, or by instructions controlling associated hardware, which may be stored in a computer-readable storage medium and loaded and executed by a processor.
To this end, an embodiment of the present invention provides a storage medium, in which a plurality of instructions are stored, and the instructions can be loaded by a processor to execute any of the steps of the power line carrier based low-carbon campus topology prediction and time service method provided in the embodiment of the present invention.
For example, the instructions may perform the steps of:
constructing a power line carrier time service system model by analyzing the actual distribution conditions and accurate time service information data packets of intelligent gateways and monitoring terminals in the intelligent park group;
based on a power line carrier time service system model, under the constraint of signal-to-interference-and-noise ratio, an optimization problem is constructed by optimizing a path selection strategy of a power line carrier time service data packet;
acquiring historical topology information and power line carrier real-time monitoring data stored in a low-carbon smart park database, and predicting the topology condition of a monitoring terminal to obtain the topological adjacency relation of the monitoring terminal;
based on the signal-to-interference-and-noise ratios among monitoring terminals in the power line carrier real-time monitoring data, the topological adjacency relation of the monitoring terminals and the constructed optimization problem, the decision of the time service information data packet path is optimized by utilizing a synchronous set game algorithm to obtain an optimal time service decision result, and the time synchronization of the park group monitoring terminals and the electrical equipment is realized by the decision result. While the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and so forth) having computer-usable program code embodied therein. The scheme in the embodiment of the application can be implemented by adopting various computer languages, such as object-oriented programming language Java and transliterated scripting language JavaScript.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.
Claims (10)
1. A low-carbon park group topology prediction and time service method based on power line carriers is characterized by comprising the following steps:
constructing a power line carrier time service system model by analyzing the actual distribution conditions and accurate time service information data packets of intelligent gateways and monitoring terminals in the intelligent park group;
based on a power line carrier time service system model, under the constraint of signal-to-interference-and-noise ratio, an optimization problem is constructed by optimizing a path selection strategy of a power line carrier time service data packet;
acquiring historical topology information and power line carrier real-time monitoring data stored in a low-carbon smart park database, and predicting the topology condition of a monitoring terminal to obtain the topological adjacency relation of the monitoring terminal;
based on the signal-to-interference-and-noise ratios among monitoring terminals in the power line carrier real-time monitoring data, the topological adjacency relation of the monitoring terminals and the constructed optimization problem, the decision of the time service information data packet path is optimized by utilizing a synchronous set game algorithm to obtain an optimal time service decision result, and the time synchronization of the park group monitoring terminals and the electrical equipment is realized by the decision result.
2. The power line carrier-based low-carbon park group topology prediction and time service method as claimed in claim 1, wherein analyzing actual distribution conditions and accurate time service information data packets of intelligent gateways and monitoring terminals in the intelligent park group specifically comprises:
analyzing the actual distribution situation of intelligent gateways and monitoring terminals in the intelligent park group, determining a set and expressing as S = { S = (S) } 0 ,s 1 ,...,s i ,...,s I In which s 0 Representing an intelligent gateway, s 1 ，s i And s I Respectively representing the 1 st, I th and I th monitoring terminals; if the connection topology of monitoring terminals of the park is unknown, the R round time service process is considered together, a set is determined and represented as R = { 1., R., R }, wherein 1, R and R respectively represent the 1 st, R and R round time service;
analyzing the accurate time service information data packet and determining s i In order to be the sender of the data packet,
a data packet receiving end; binary variable for indicating variable of packet path selection
It is shown that, among others,
indicating the r-th round of time service
From s i Receive data packet, otherwise
Determining binary variables
Indicating variables for the topological connection between the intelligent gateway and each monitoring terminal
Is denoted by s i And with
Connect otherwise
3. The power line carrier based low-carbon park group topology prediction and time service method of claim 2, wherein the power line carrier time service system model comprises: the system comprises a power line carrier time service data packet transmission model, a time service delay model and an accumulated time service error model;
the method for constructing the power line carrier time service data packet transmission model specifically comprises the following steps:
the complex electromagnetic environment and noise interference of the low-carbon smart park are considered, the transmission of power line carrier time service data packets and the r-th round time service are realized based on the orthogonal frequency division multiplexing technology
From s i The rate at which packets are received is:
wherein, N s For the transmission rate of the OFDM symbols,
in order to transmit the power, the power is transmitted,
represents the path gain; wherein,
and sigma 0 Path frequency response, electromagnetic interference and Gaussian white noise power;
representing SINR gaps, i.e. resistance to SINR fading(ii) a Wherein, P e Representing the target bit error rate, Q -1 (x) To represent
The inverse function of (c);
constructing the time service delay model; the method specifically comprises the following steps:
dividing each round of time service into a plurality of time slots with the length of tau, and s at the beginning of each time slot i Starting to connect
Transmitting a power line carrier time service data packet; in the multi-hop transmission of the low-carbon intelligent park monitoring terminal topology, the r-th round of time service
The delay of receiving a data packet is determined by the sender s i Delay sum of received data packet
From s i The single-hop transmission delay for receiving a data packet is represented as:
wherein,
denotes s i The number of time slots experienced by the received data packet,
is composed of
From s i The single-hop transmission delay of a received data packet is expressed as:
wherein, U r The size of the r-th round of time service data packet is represented;
the method for constructing the accumulative time service error model specifically comprises the following steps:
determining the r-th wheel
Accumulated time service error of received data packet
Comprises the following steps:
wherein,
time-giving for the r-th round
From s i Receiving the accumulated time service error of the data packet, namely:
wherein,
indicating the r-th round of time service
From s i The single-hop time service error formed by receiving the data packet follows normal distribution with the average error value of alpha and the standard deviation of beta, i.e.
Time service s for the r-th round i And receiving the accumulated time service error of the data packet.
4. The power line carrier based low-carbon park group topology prediction and time service method according to claim 3, characterized in that an optimization objective is to minimize the weighted sum of average time service delay and time service error by optimizing a path selection strategy of a power line carrier time service data packet under the constraint of signal-to-interference-and-noise ratio, and the optimization problem is specifically constructed as follows:
C1:
C2:
C3:
C4:
wherein, χ is a weight parameter used for dynamically balancing time delay and time error; c1 and C2 are path selection constraints and represent each round of time service receiving end
Terminating at most from one transmissionReceiving a data packet; c3 represents
And s i When the device is not connected to the power source,
cannot be obtained from s i Receiving a data packet; in order to ensure the transmission quality of the power line carrier time service data packet, the signal-to-interference-and-noise ratio of the path is constrained, namely C4:
5. the power line carrier-based low-carbon park group topology prediction and time service method according to claim 1, wherein the predicting of the topology condition of the monitoring terminal specifically comprises:
selecting a time service path for the accurate time service information data packet based on the topological adjacency relation of the monitoring terminal;
inputting the historical topology information into a preset BP neural network for pre-training to obtain a trained BP neural network model;
and inputting the real-time monitoring data of the power line carrier into the trained BP neural network model based on the constructed power line carrier time service system model to obtain the topological adjacency relation of the monitoring terminal.
6. The power line carrier based low-carbon park group topology prediction and time service method according to claim 5, wherein the inputting of historical topology information into a preset BP neural network for pre-training specifically comprises:
inputting a park monitoring terminal topological adjacency matrix, topological characteristic data, historical power line carrier time delay and historical power line carrier time error stored in a low-carbon intelligent park database into a preset BP neural network for pre-training;
the preset BP neural network is specifically constructed as follows:
the BP neural network comprises an input layer, a hidden layer and an output layer, the number of neurons of the input layer is X, the number of neurons of each layer of the hidden layer is Y, and the number of neurons of the output layer is Z;
the hidden layer parameters are Q (A, B), Q is a BP neural network parameter matrix, A is a hidden layer weight matrix, and B is a threshold matrix;
an input signal matrix of a BP neural network input layer suitable for topology prediction of a monitoring terminal is represented as follows:
wherein,
respectively representing input signals of 1 st, X th and X th input layer neurons;
expressing the activation function of the BP neural network as:
wherein κ is an activation function parameter; the BP neural network hidden layer function suitable for the topology prediction of the monitoring terminal is as follows:
wherein,
as weights between input layer neurons and hidden layer neurons, b y To hide the layer threshold, N y Is output for the y neuron of the hidden layer;
the BP neural network output layer function suitable for the topology prediction of the monitoring terminal is as follows:
wherein,
as weights between hidden layer neurons and output layer neurons, c z As output layer threshold, G z Output for the z-th neuron;
expressing the loss function of the BP neural network as:
wherein M is the number of samples, k is the neural network training sample output, k * M is the dimensionality of the data for the desired output; updating the weight according to the direction of the negative gradient of the error; after an input signal matrix and expected output are given, iteration is repeatedly carried out on each input signal matrix, when all input signal matrix data are repeatedly iterated in sequence, and after sample training is finished, whether the index function meets the precision or not is judged; and stopping training if the index function meets the precision, or retraining until the precision is met, and obtaining the trained BP neural network model suitable for the topology prediction of the monitoring terminal.
7. The power line carrier based low carbon park group topology prediction and time service method as claimed in claim 6, wherein the real-time monitoring data of the power line carrier is input into a trained BP neural network model to obtain the topological adjacency relationship of the monitoring terminal, and specifically comprises:
when each round of time service process starts, inputting real-time monitoring data of power line carriers among the monitoring terminals into a trained BP neural network model to obtain the topological connection relation of the monitoring terminals in the current round of time service; topological adjacency matrix W of monitoring terminal r Can be prepared from the following formulaRepresents:
8. the power line carrier-based low-carbon park group topology prediction and time service method of claim 1, wherein before optimizing a decision of a time service information data packet path by using a synchronous group game algorithm, the method further comprises:
firstly, in the r round of time service, a power line carrier time service data packet sending end and a plurality of time service data packet receiving ends are defined as a multi-channel broadcast group which is marked as
The utility function of (a) can be represented by:
wherein,
is composed of
The number of the receiving ends of the medium data packet;
defining the synchronous group Game of the r-th round time service as Game r (Φ r V), wherein phi represents the set of monitoring terminals participating in the game and satisfies
V represents the value of the synchronization group, defined as:
in each synchronization group, whether the synchronization group allows the data packet receiving end to add depends on the contribution of the synchronization group to the value of the synchronization group, and if the receiving end seriously increases the average time delay and time error of the multi-path broadcast group, the receiving end is rejected; therefore, the receiving end in the r-th round time service synchronization group
Gain of (2)
Is defined as the contribution to the value of the synchronization group, calculated as:
wherein,
represent
Joining a Sync group
9. The power line carrier based low-carbon park group topology prediction and time service method as claimed in claim 8, wherein a decision of a time service information data packet path is optimized by using a synchronous set game algorithm, specifically:
step 1: and (3) initializing a synchronization group:
calculating the priority of each receiving end to all sending ends receiving the time service information data packets according to the SINR and the topological adjacency relation among the monitoring terminals, wherein the preference sequence is arranged in a descending order according to the SINR; for the receiving end
If present, satisfy
The sender of (2), then add it to the set
At the same time, the user can select the required time,
in (1)
Temporarily joining a synchrony group
Wherein s is i In the priority order of first; if the receiving end
Is not satisfied with any transmitting end
Then the receiving end
Does not participate in the current round of time service;
and 2, step: establishing a synchronization group:
when all the synchronization groups of the time slot are temporarily established, the receiving end, for example
According to the formula
The calculated income, namely the optimization target, is selected to join other synchronization groups; if it is not
Then
Selecting away from a current synchronization group
To join the synchronization group
The receiving end in the system can continuously select and replace the synchronous group according to the income until no receiving end selects and replaces the synchronous group;
and step 3: and finally establishing a synchronization group and transmitting a power line carrier time service data packet:
repeating the step 2 until all receiving ends do not change the selection; the time when the synchronization group is finally formed is called a decision point; after that, the sending end in each synchronization group starts to transmit the power line carrier timing data packet in the same synchronization group; after each sending end in all the synchronous groups completes time service, the synchronous groups of the time slot are dispersed;
and 4, step 4: and the next time slot transmission:
at the end of each time slot, checking whether all synchronization groups complete transmission; then, a receiving end which receives the power line carrier time service data packet in the current time slot is used as a sending end for the next time slot transmission; the algorithm is transferred to step 1; when each monitoring terminal completes time service, the current round of time service is finished.
10. Low carbon garden group topology prediction and time service system based on power line carrier, characterized in that, the system is applied to the control layer, the system includes:
the first construction module is used for constructing a power line carrier time service system model by analyzing the actual distribution condition and the accurate time service information data packet of the intelligent gateway and the monitoring terminal in the intelligent park group;
the second construction module is used for constructing an optimization problem by optimizing a path selection strategy of a power line carrier time service data packet under the constraint of a signal-to-interference-and-noise ratio based on a power line carrier time service system model;
the topology prediction module is used for acquiring historical topology information and power line carrier real-time monitoring data stored in the low-carbon intelligent park database, predicting the topology condition of the monitoring terminal and obtaining the topological adjacent relation of the monitoring terminal;
and the decision optimization module is used for optimizing the decision of the time service information data packet path by utilizing a synchronous set game algorithm based on the signal-to-interference-and-noise ratio among the monitoring terminals, the topological adjacency relation of the monitoring terminals and the constructed optimization problem in the power line carrier real-time monitoring data to obtain an optimal time service decision result, and the decision result realizes the time synchronization of the park group monitoring terminals and the electrical equipment.
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