Method and apparatus for power line carrier signal transmission in DC lighting systems

Abstract

The present application relates to the field of communication transmission technology, and specifically to a method and device for power line carrier signal transmission applied to a DC lighting system. The method includes: obtaining the current of each street lamp controlled by each concentrator in the DC lighting system, constructing a current difference index and a noise interference index between any two adjacent street lamps, analyzing the voltage drop difference and distance difference between any two adjacent street lamps, and calculating the signal impact index of the power line between any two adjacent street lamps based on the difference in the amplitude of the control signal; according to the time domain difference and frequency domain difference between the control signal sent by the concentrator and the control signal received by the terminal street lamp, and combining the change in the timestamp of the control signal sent by the concentrator and the control signal received by each street lamp, an overall damage index is constructed, and based on the noise interference index, the signal impact index and the overall damage index, an optimization algorithm is used to obtain the best routing forwarding path for each concentrator. The present application can improve the transmission effect of the carrier signal.

Description

Technical Field

[0001] The present application relates to the field of communication transmission technology, and specifically to a power line carrier signal transmission method and device applied to a DC lighting system. Background Art

[0002] The LED street lights in the intelligent DC lighting system transmit control signals to the control center through power line carrier communication (PLC), thereby realizing intelligent control of the LED street lights. However, since the control center controls multiple street lights at the same time and the distance between street lights is relatively far, the resistance on the DC line will cause the control signal to gradually weaken during long-distance transmission, thereby affecting the signal transmission distance. In response to the above problems, the prior art proposes a method of using routing forwarding technology to increase the signal transmission distance. In the routing forwarding technology, each street light is regarded as a route that can receive and forward signals, thereby increasing the transmission distance. However, due to the low rate of PLC, the data of carrier communication cannot be forwarded indefinitely, otherwise it will cause the channel to be occupied for too long, resulting in problems with the control signal.

[0003] In the process of signal forwarding, people usually only focus on how to minimize the channel occupation time under the premise that all street lamps receive the control signal; but they do not consider the interference effect of the time-varying and strong interference of the power line carrier communication channel on the control signal. Although the demand for less channel occupation time is met, the control signal of the street lamp may be greatly interfered when forwarding the signal. If the interfered signal is forwarded again, it will further affect the transmission accuracy of the control signal, making it impossible for subsequent street lamps to recognize the control signal, resulting in poor transmission effect of the control signal and failure to achieve effective control of the street lamp. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of this application is to provide a power line carrier signal transmission method and device applied to a DC lighting system. The technical solutions adopted are as follows:

[0005] The embodiment of the present application provides a power line carrier signal transmission method applied to a DC lighting system, comprising the following steps:

[0006] Obtain the current data of each street lamp controlled by each concentrator in the DC lighting system;

[0007] For each concentrator, based on the correlation between the current data of any two adjacent street lamps and the deviation between the current data of any two adjacent street lamps, a current difference index between the any two adjacent street lamps is constructed, and the noise interference index of the power line between the any two adjacent street lamps is determined by combining the difference between the current difference index between the any two adjacent street lamps and the current difference index between other any two adjacent street lamps;

[0008] Analyze the voltage drop difference between any two adjacent street lamps and the difference in the received control signals, and calculate the signal influence index of the power line between any two adjacent street lamps in combination with the current difference index between the any two adjacent street lamps;

[0009] According to the time domain difference and frequency domain difference between the control signal sent by the concentrator and the control signal received by the terminal street lamp, the time domain difference coefficient and the frequency domain difference coefficient are constructed. Combined with the changes in the timestamps of the control signal sent by the concentrator and the control signal received by each street lamp, the overall damage index of signal transmission is constructed.

[0010] Each concentrator and the street lamp controlled by it are used as nodes to construct each graph model, and the optimal routing forwarding path of each concentrator is obtained by using an optimization algorithm in combination with the noise interference index, the signal impact index and the overall damage index.

[0011] Preferably, the expression of the current difference index between any two adjacent street lamps is:

[0012] ; In the formula, is the current difference index of the power line between the u-th and v-th street lamps; B is the deviation from the sine index between the u-th and v-th street lamps, where the current data of each street lamp at all acquisition moments constitute the current sequence of each street lamp, and the DTW distances between the current sequences of the u-th and v-th street lamps and the corresponding standard sine signals are calculated respectively, and the average of the two DTW distances is the deviation from the sine index; P is the absolute value of the Pearson correlation coefficient between the current sequences of the u-th and v-th street lamps; To avoid constants with zero denominators.

[0013] Preferably, the expression of the noise interference index of the power line between any two adjacent street lamps is:

[0014] ; In the formula, , are the noise interference index and current difference index of the power line between the uth and vth street lamps respectively; It is expressed as the current difference index of the power line between the nth and n+1th street lamps; m is the number of street lamps.

[0015] Preferably, the expression of the signal influence index of the power line between any two adjacent street lamps is:

[0016] ; In the formula, are the signal influence index and current difference index of the power line between the uth and vth street lamps respectively; is the voltage drop deviation between the uth and vth street lamps, where the average values ​​of the voltage drops of the uth and vth street lamps at all times are counted respectively, and the absolute difference between the two average values ​​is the voltage drop deviation between the uth and vth target street lamps; To avoid constants with zero denominators; is the DTW distance between the control signals of the u-th and v-th street lights; , are the average amplitudes of the control signals received by the u-th and v-th street lamps respectively.

[0017] Preferably, the construction of the time domain difference coefficient includes: demodulating the control signal sent by the concentrator and the control signal received by the terminal street lamp, sampling and processing the demodulated signals respectively, constructing a sending sequence and a receiving sequence, and counting the absolute difference in skewness between the sending sequence and the receiving sequence as the time domain difference coefficient, wherein the terminal street lamp is the street lamp farthest from the concentrator.

[0018] Preferably, the construction of the frequency domain difference coefficient includes: performing frequency domain transformation on the sending sequence and the receiving sequence, respectively obtaining the spectrum entropy of the two frequency domain signals after the frequency domain transformation of the sending sequence and the receiving sequence, and taking the absolute difference between the two spectrum entropies as the frequency domain difference coefficient.

[0019] Preferably, the expression of the overall impairment index of the signal transmission is:

[0020] ; In the formula, K is the overall damage index of signal transmission; L is the delay fluctuation coefficient, where the timestamp of the control signal sent by the concentrator and the timestamp of each street lamp receiving the control signal are arranged from small to large to form a timestamp sequence, and the variance of the first-order difference sequence of the timestamp sequence is used as the delay fluctuation coefficient; S is the time domain difference coefficient; O is the frequency domain difference coefficient.

[0021] Preferably, the acquisition of the best routing forwarding path of each concentrator includes:

[0022] According to the signal influence index and noise interference index between any two connected nodes in the graph model, the pheromone parameters in the ant colony algorithm are constructed, and the ant colony algorithm is used to obtain the optimal routing forwarding path in the graph model, where the objective function is: ; In the formula, Y is the objective function value; T is the number of routing forwarding during signal transmission; K is the overall damage index of signal transmission;

[0023] The constraints are: ; Where N is the number of nodes in the graph model; t represents the preset number of communication hops; It is expressed as the number of communication hops between the i-th and j-th nodes in the graph model, where if nodes i and j are adjacent, the number of communication hops between nodes i and j is 1; if node i is to node j and node j is to node k, the number of communication hops between nodes i and k is 2, and so on.

[0024] An embodiment of the present application also provides a power line carrier signal transmission device for a DC lighting system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the steps of any one of the above methods when executing the computer program.

[0025] It can be seen from the above that the power line carrier signal transmission method and device for a DC lighting system provided in the present application have at least the following beneficial effects:

[0026] This application takes into account that the noise interference contained in the power lines between different adjacent street lamps is not consistent, and constructs a noise interference index to reflect the noise interference of the power lines between adjacent street lamps; then, considering that the load will also cause serious reduction in the carrier signal, a signal impact index is constructed to comprehensively reflect the degree of influence of the power line on the carrier signal; finally, by constructing an overall damage index, the degree of interference of the control signal sent by the concentrator during the transmission process is calculated, thereby reflecting the effect of signal forwarding;

[0027] In order to solve the problem that the prior art only considers the shortest channel occupation time, but causes greater interference to the signal, thus affecting the recognition accuracy, the present application uses the overall damage index and optimization algorithm to locate the street lamp node that is most suitable for signal forwarding, which not only satisfies the short channel occupation time but also ensures the signal recognition accuracy, thereby improving the transmission effect of the carrier signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A flowchart of the steps of the power line carrier signal transmission method applied to a DC lighting system provided in this application;

[0030] Figure 2 A communication diagram of a DC lighting system provided for this application. DETAILED DESCRIPTION

[0031] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following is a detailed description of the power line carrier signal transmission method and device for DC lighting system proposed in the present application, its specific implementation, structure, features and effects in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0032] Unless otherwise specified and limited, terms such as "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a circuit structure, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such articles or devices. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the article or device including the element. In addition, the term "and\or" used herein includes any and all combinations of one or more related listed items. All technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of this application.

[0033] The specific scheme of the power line carrier signal transmission method and device for a DC lighting system provided by the present application is described in detail below with reference to the accompanying drawings.

[0034] See also Figure 1 , which shows a flowchart of a power line carrier signal transmission method applied to a DC lighting system provided by an embodiment of the present application, including the following steps:

[0035] Step 1: Obtain the current data of each street lamp controlled by each concentrator in the DC lighting system.

[0036] First, in the intelligent DC lighting system, the control center sends control instructions to the concentrator node, and then the concentrator node sends control instructions to the LED street light node. The control instructions are parsed by the built-in chip of the street light, so as to perform intelligent brightness adjustment, switch control, and upload the relevant power parameter data of the street light node to realize the control of the street light terminal node. The DC lighting system communication diagram is as follows Figure 2 As shown, Figure 2Number 1 indicates DC wires and cables; power line carriers are used for communication transmission between the control center and each concentrator, and between the concentrator and each LED street lamp.

[0037] In this embodiment, the ath concentrator in the DC lighting system is taken as an example for analysis. After the ath concentrator sends a control instruction, this embodiment uses the existing routing forwarding technology to forward the control signal, and synchronously and in real time obtains the current data of each street lamp through the control center of the DC lighting system. In this embodiment, the data acquisition frequency is 1KHz, and the acquisition time starts from the time when the concentrator sends the control instruction until all street lamps receive the control instruction. The current data of each street lamp is collected in the order of the acquisition time to form a current sequence of each street lamp.

[0038] Similarly, the control center of the DC lighting system obtains the timestamp when the concentrator sends the control signal, the timestamp when each street lamp receives the control signal, the received control signal, and the location data of each street lamp.

[0039] Step 2: For each concentrator, based on the correlation between the current data of any two adjacent street lamps and the deviation between the current data of any two adjacent street lamps, construct a current difference index between the any two adjacent street lamps, and combine the degree of difference between the current difference index between the any two adjacent street lamps and the current difference index between any other two adjacent street lamps to determine the noise interference index of the power line between the any two adjacent street lamps.

[0040] Since the noise in the power line has time-varying characteristics and the noise difference between different areas is also large, and because the distance between street lamps is far and there are branch wires, the degree of noise interference contained in the power lines between different street lamps is also inconsistent. Therefore, when the control signal is communicated by carrier wave in the power line, the noise interference of the power line between adjacent street lamps can be calculated to reflect the interference effect on the control signal after passing through this section of the power line.

[0041] For any two adjacent street lamps, in this embodiment, taking the u-th and v-th street lamps adjacent to each other on the same power line as an example, it should be noted that in this embodiment, the street lamp that receives the control signal first is u. Since the interference noise will not only interfere with the communication signal, but also affect the current flowing between the two street lamps, the current waveform changes caused by the noise interference in the power line of the current sequence of the u-th and v-th street lamps can be calculated to reflect the degree of noise interference in the power line between the u-th and v-th street lamps.

[0042] If the noise interference in the power line between the u-th and v-th street lamps is smaller, the waveform of the current data obtained at the u-th and v-th street lamps will be closer to a sine wave; if the interference in the power line is greater, the difference in the current waveform at the u-th and v-th street lamps will be greater, and the waveform will deviate more from a sine wave.

[0043] Therefore, in this embodiment, a standard sinusoidal signal of each current sequence is obtained. Preferably, the u-th current sequence is subjected to a fast Fourier transform and converted from a time domain signal to a frequency domain signal, which is recorded as the u-th frequency domain current signal. According to the fundamental frequency, phase and amplitude of the u-th frequency domain current signal, a standard sinusoidal signal corresponding to the u-th current sequence is constructed. Fast Fourier transform and signal generation technology are well-known technologies in the field of communications and will not be described in detail here. It should be noted that in actual application scenarios, the implementer can choose the method for obtaining the standard sinusoidal signal corresponding to each current sequence at his / her own discretion, and this embodiment does not impose any special restrictions on this.

[0044] Furthermore, the DTW distance between the current sequence of the uth street lamp and its corresponding standard sinusoidal signal is calculated, and the DTW distance corresponding to the current sequence of the vth street lamp is obtained in the same way. The smaller the DTW distance, the more consistent the waveform of each current sequence is with its corresponding sinusoidal waveform, the less likely the current waveform is distorted, and the less noise interference is.

[0045] The average of the DTW distances corresponding to the two current sequences is used as the deviation sine index of the two street lamps. The larger the deviation sine index, the greater the deviation between the current sequence waveforms of the two adjacent street lamps and the sine waveform, and the more serious the noise interference at the uth and vth street lamps.

[0046] Therefore, according to the correlation between the deviation sine index and the corresponding current sequence between any two adjacent street lamps, the current difference index of the power line between any two adjacent street lamps is calculated. In this embodiment, the specific calculation relationship is:

[0047] ; In the formula, is the current difference index of the power line between the uth and vth street lamps; B is the deviation sine index between the uth and vth street lamps; P is the absolute value of the Pearson correlation coefficient between the current series of the uth and vth street lamps; To avoid a constant with a denominator of zero, the value range is 0 to 1. In this embodiment, to avoid a constant with a denominator of 0 and not affect subsequent calculations, the value is 0.001.

[0048] It can be understood that the smaller the deviation from the sine index B is, the closer the current sequence waveforms of two adjacent street lamps are to the sine waveform; the larger the absolute value P of the Pearson correlation coefficient between the two current sequences is, the more consistent the change trend of the current waveforms between the two adjacent street lamps is. The smaller it is, the smaller the noise interference between the u-th and v-th street lamps will be, and the better the signal communication effect between the street lamps will be.

[0049] Furthermore, considering that the noise interference in the power line may not be consistent in different time periods, and it is necessary to find a suitable street lamp from all street lamps for signal forwarding, it is possible to compare with the current difference index between other adjacent street lamps, thereby further evaluating the noise interference index of the power line between the u-th and v-th street lamps in the same time period.

[0050] The above process of this embodiment is repeated to obtain the current difference index of the power line between any two adjacent street lamps.

[0051] Further, according to the current difference index between any two adjacent street lamps, and in combination with the deviation of the current difference index between any two adjacent street lamps relative to the current difference index between any other two adjacent street lamps, the noise interference index of the power line between any two adjacent street lamps is calculated. In this embodiment, the specific calculation formula is:

[0052] ; In the formula, is the noise interference index of the power line between the uth and vth street lamps; It is expressed as the current difference index of the power line between the nth and n+1th street lights; is the current difference index of the power line between the uth and vth street lamps; m is the number of street lamps.

[0053] in, The larger the value is, the greater the difference in current waveform between the uth and vth street lamps is, reflecting the more serious the noise interference is; at the same time, the greater the deviation between the current difference index of the power line between the uth and vth street lamps and the current difference index between other adjacent street lamps, reflecting the more significant the noise interference of the power line between the uth and vth street lamps. Therefore, the larger the noise interference index is, the stronger the noise interference contained in the power line between the uth and vth street lamps is compared with other street lamps, the greater the interference to the communication signal is, and the less suitable the vth street lamp is for signal forwarding.

[0054] Step 3: Analyze the voltage drop difference between any two adjacent street lamps and the difference in the received control signals, and calculate the signal influence index of the power line between any two adjacent street lamps in combination with the current difference index between the two adjacent street lamps.

[0055] Furthermore, if there are too many loads in the power line, even if the loads are not frequently connected or disconnected, the carrier signal will still be severely reduced; at the same time, because when the linear load is running smoothly, the current waveform will still be close to a sine wave. Therefore, if only the above current deviation index is used, it cannot fully reflect the load situation in the power line, and further evaluation of the current load between adjacent street lamps is required.

[0056] In this embodiment, the voltage drop of each street lamp at each moment is obtained. Specifically, the line length and power line resistance of the power line between the u-th and v-th street lamps are obtained through the control center, and according to the current values ​​of the u-th and v-th street lamps at each moment, the voltage drop values ​​of the u-th and v-th street lamps at each moment are obtained through the voltage drop calculation method, and the average of the voltage drop values ​​at all moments is recorded as the average voltage drop of the u-th and v-th street lamps.

[0057] The absolute difference between the average voltage drops of the uth and vth street lamps is recorded as the voltage drop deviation between the uth and vth street lamps. If the voltage drop deviation is larger, it means that there are more loads between the uth and vth street lamps, resulting in a larger voltage drop difference. The calculation method of the voltage drop is a well-known technology in the electric power field and will not be repeated here.

[0058] Furthermore, based on the voltage drop difference between any two adjacent street lamps and the difference in the received control signals, a signal influence index of the power line between any two adjacent street lamps is constructed. In this embodiment, the specific calculation formula is:

[0059] ; In the formula, is the signal influence index of the power line between the uth and vth street lamps; is the voltage drop deviation between the uth and vth street lamps; is the DTW distance between the control signals of the u-th and v-th street lights; , are the average amplitudes of the control signals received by the u-th and v-th street lamps respectively.

[0060] The voltage drop deviation H reflects the load condition in the power line. The larger the voltage drop deviation, the more power load there is between the uth and vth street lamps, and the greater the attenuation effect on the carrier signal. The larger the DTW distance between the control signals of the uth and vth street lamps, the greater the difference between the control signals of the uth and vth street lamps, and the greater the degree of noise interference or signal attenuation interference. Reflects the difference between the signal amplitudes of adjacent street lamps. Considering that noise interference will affect the control signal amplitude of the next street lamp node, the control signal of the next street lamp node is processed first; The larger the signal impact index is, the more inconsistent the signal amplitude is between two adjacent street lamps, and the greater the signal attenuation or noise interference is. The larger the signal impact index is, the greater the influence of the power line on the carrier signal between adjacent street lamps is, and the greater the signal error after passing through this section of the power line is. Therefore, it is more necessary to treat the previous street lamp node as a forwarding node, otherwise the error may be further increased.

[0061] So far, according to the above process of this embodiment, the signal influence index of the power line between any two adjacent street lamps can be obtained.

[0062] Step 4: Based on the time domain differences and frequency domain differences between the control signal sent by the concentrator and the control signal received by the endpoint street lamp, the time domain difference coefficient and the frequency domain difference coefficient are constructed. Combined with the changes in the timestamps of the control signal sent by the concentrator and the control signal received by each street lamp, the overall damage index of the signal transmission is constructed.

[0063] The ultimate goal of the routing forwarding technology is to enable the terminal street lamp to receive the control command issued by the concentrator. However, if the control signal is subject to severe signal interference during the forwarding process, the terminal street lamp will be able to receive the signal but will not be able to recognize the signal. In this embodiment, the street lamp farthest from the ath concentrator is recorded as the terminal street lamp. Therefore, the suitability of the street lamp node selected for signal forwarding during this routing forwarding process can be evaluated by analyzing the degree of damage to the control signal received by the terminal street lamp.

[0064] Furthermore, the time domain characteristics of the control signal sent by the concentrator and the control signal received by the terminal street lamp are analyzed. According to the modulation frequency and modulation algorithm of the DC lighting system, the control signal sent by the concentrator and the control signal received by the terminal street lamp are demodulated. The demodulated signals are sampled and processed respectively, and the sending sequence and the receiving sequence are constructed. The absolute difference in skewness between the sending sequence and the receiving sequence is counted as the time domain difference coefficient.

[0065] Preferably, in this embodiment, according to the number of current data in the current sequence, the downlink signal and the received signal are sampled and processed, and the downlink sequence and the received sequence are constructed respectively, wherein the number of elements in the downlink sequence and the received sequence are the same as the number of current data in the current sequence. Further, the skewness s1 of the downlink sequence and the skewness s2 of the received sequence are calculated respectively, and the absolute difference between the skewness s1 and s2 is recorded as the time domain difference coefficient. The skewness can reflect the degree of symmetry of the distribution of the signal data on both sides of the mean. If the received signal is subject to greater noise interference, the high-frequency content increases, and its skewness will be greatly different from the downlink signal.

[0066] At the same time, in this embodiment, the frequency domain characteristics of the control signal are analyzed, and the frequency domain transformation is performed on the sending sequence and the receiving sequence. Preferably, in this embodiment, fast Fourier transform is used to perform frequency domain transformation on the sending sequence and the receiving sequence respectively. Further, the spectrum entropy of the two frequency domain signals after the conversion of the sending sequence and the receiving sequence is obtained respectively, and the absolute difference between the two spectrum entropies is recorded as the frequency domain difference coefficient of the terminal street lamp. The spectrum entropy reflects the dispersion and complexity of the signal spectrum. The signal attenuation and noise interference in the signal transmission process will significantly interfere with the complexity of the signal entropy in the frequency domain. It should be noted that the calculation of skewness and spectrum entropy is a well-known technology and will not be repeated here.

[0067] The timestamps of the control signals sent by the concentrator and the timestamps of the control signals received by each street lamp are used to construct a timestamp sequence in ascending order. The first-order difference sequence of the timestamp sequence is obtained, and the variance of the first-order difference sequence is recorded as the delay fluctuation coefficient of the timestamp sequence. Since the distance between street lamps is consistent by default, the smaller the delay fluctuation coefficient, the less noise interference in the power line, and the fewer times of routing forwarding, so that the timestamp difference when each street lamp receives the control signal is relatively consistent.

[0068] Therefore, the overall impairment index of signal transmission is calculated based on the time domain difference coefficient, the frequency domain difference coefficient and the delay fluctuation coefficient. In this embodiment, the specific expression is: ; In the formula, K is the overall damage index of signal transmission; L is the delay fluctuation coefficient of the timestamp sequence; S is the time domain difference coefficient; O is the frequency domain difference coefficient of the terminal street lamp.

[0069] It can be understood that the delay fluctuation coefficient L can reflect the degree of power line noise interference and the efficiency of routing forwarding. The smaller the delay fluctuation coefficient, the less noise in the power line, which does not have a large delay impact on the signal, and at the same time indicates that the forwarding efficiency of the street lamp is high; the time domain difference coefficient can reflect the difference in data distribution symmetry between the signal received by the terminal street lamp and the signal sent by the concentrator, and the frequency domain difference coefficient can reflect the difference between the complexity of the signal in the frequency domain. If the value of S+O is larger, the control signal is more affected by signal interference and attenuation in the power line. Therefore, the larger the overall damage index, the greater the interference to the signal when the control signal is transmitted to the terminal street lamp, and the more inconsistent the transmission delay between adjacent street lamps during the transmission process, which indicates that the street lamp node for routing forwarding is less suitable.

[0070] Step 5: Use each concentrator and the street lamps it controls as nodes to construct each graph model, and use an optimization algorithm to obtain the best routing forwarding path for each concentrator in combination with the noise interference index, the signal impact index, and the overall damage index.

[0071] Furthermore, the ath concentrator is taken as the first node in the graph model, and all street lamps controlled by the ath concentrator are taken as nodes in the graph. Whether the nodes are connected is determined by the power lines to construct the graph model, and the street lamp communication constraint conditions are constructed according to the channel attenuation range of signal forwarding. In this embodiment, the constraint conditions are:

[0072] ; In the formula, It represents the number of communication hops between the i-th and j-th nodes in the graph model, and N is the number of nodes in the graph model; t represents the preset number of communication hops, which is set to 20 in this embodiment, that is, it represents that the maximum communication distance between the i-th and j-th nodes cannot exceed 20 hops. Regarding the number of communication hops, for the convenience of understanding, an example is given in this embodiment: if nodes i and j are adjacent, the number of communication hops is 1; if i to j, and j to k, the number of communication hops between nodes i and k is 2. In this embodiment, the number of communication hops between any two nodes does not exceed 20.

[0073] Furthermore, an objective function is constructed according to the overall impairment index of signal transmission. In this embodiment, the expression is: ; In the formula, Y is the objective function value; T is the number of routing forwarding during signal transmission; K is the overall damage index of signal transmission.

[0074] Finally, for the graph model corresponding to each concentrator, the graph model is used as the input of the ant colony algorithm. In this embodiment, the number of iterations is set to 50, the number of ants is the number of street lamps, the information factor and the heuristic factor are 1, and the reciprocal of the sum of the signal influence index G and the noise interference index A between any two connected nodes is calculated respectively as the pheromone of the edge between any two connected nodes. The larger the pheromone, the more suitable the nodes in the path are for signal forwarding. The ant colony algorithm outputs the optimal routing forwarding path that minimizes the value of the objective function Y, and forwards the signal through the street lamp nodes in the optimal routing forwarding path, thereby satisfying the premise of occupying the channel for a short time and minimizing the interference to the carrier signal.

[0075] The above process of this embodiment is repeated to obtain the best routing forwarding path of each concentrator, thereby realizing the transmission of the power line carrier signal applied to the DC lighting system.

[0076] Based on the same inventive concept as the above method, an embodiment of the present application also provides a power line carrier signal transmission device applied to a DC lighting system, including a memory, a processor, and a computer program stored in the memory and running on the processor, and when the processor executes the computer program, the steps of any one of the above-mentioned power line carrier signal transmission methods applied to a DC lighting system are implemented.

[0077] It is to be understood that the sequence of the embodiments of the present application described above is for description only and does not represent the advantages and disadvantages of the embodiments. The above describes specific embodiments of the present specification. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0078] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0079] The above content is only an implementation method of the present application and is not intended to limit the scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the protection scope of the present application.

Claims

1. A power line carrier signal transmission method for a DC lighting system, characterized in that: The following steps are involved: Obtain the current data of each street lamp controlled by each concentrator in the DC lighting system; For each concentrator, based on the correlation between the current data of any two adjacent street lamps and the deviation between the current data of any two adjacent street lamps, a current difference index between the any two adjacent street lamps is constructed, and the noise interference index of the power line between the any two adjacent street lamps is determined by combining the difference between the current difference index between the any two adjacent street lamps and the current difference index between other any two adjacent street lamps; Analyze the voltage drop difference between any two adjacent street lamps and the difference in the received control signals, and calculate the signal influence index of the power line between any two adjacent street lamps in combination with the current difference index between the any two adjacent street lamps; According to the time domain difference and frequency domain difference between the control signal sent by the concentrator and the control signal received by the terminal street lamp, the time domain difference coefficient and the frequency domain difference coefficient are constructed. Combined with the changes in the timestamps of the control signal sent by the concentrator and the control signal received by each street lamp, the overall damage index of signal transmission is constructed. Each concentrator and the street lamps controlled by it are used as nodes to construct each graph model, and an optimization algorithm is used to obtain the best routing forwarding path of each concentrator in combination with the noise interference index, the signal impact index and the overall damage index; The expression of the noise interference index of the power line between any two adjacent street lamps is: In the formula, A u,v , C u,v are the noise interference index and current difference index of the power line between the uth and vth street lamps respectively; C n,n+1 It is expressed as the current difference index of the power line between the nth and n+1th street lamps; m is the number of street lamps; The expression of the signal influence index of the power line between any two adjacent street lamps is: In the formula, G u,v , C u,v are the signal impact index and current difference index of the power line between the uth and vth street lamps respectively; H u,v is the voltage drop deviation between the uth and vth street lamps, where the average values ​​of the voltage drops of the uth and vth street lamps at all times are counted respectively, and the absolute difference between the two average values ​​is the voltage drop deviation between the uth and vth target street lamps; τ is a constant to avoid the denominator being zero; D u,v is the DTW distance between the control signals of the uth and vth street lights; F u 、F v are the average amplitudes of the control signals received by the u-th and v-th street lamps respectively; The expression of the overall impairment index of the signal transmission is: K = L × (S + O); where K is the overall damage index of signal transmission; L is the delay fluctuation coefficient, where the timestamp of the control signal sent by the concentrator and the timestamp of each street lamp receiving the control signal are arranged from small to large to form a timestamp sequence, and the variance of the first-order difference sequence of the timestamp sequence is used as the delay fluctuation coefficient; S is the time domain difference coefficient; O is the frequency domain difference coefficient.

2. The power line carrier signal transmission method for a DC lighting system according to claim 1, characterized in that: The expression of the current difference index between any two adjacent street lamps is: In the formula, C u,v is the current difference index of the power line between the u-th and v-th street lamps; B is the deviation from the sine index between the u-th and v-th street lamps, where the current data of each street lamp at all acquisition moments constitute the current sequence of each street lamp, and the DTW distances between the current sequences of the u-th and v-th street lamps and the corresponding standard sinusoidal signals are calculated respectively, and the average of the two DTW distances is the deviation from the sine index; P is the absolute value of the Pearson correlation coefficient between the current sequences of the u-th and v-th street lamps; τ is a constant to avoid the denominator being zero.

3. The power line carrier signal transmission method for a DC lighting system according to claim 1, characterized in that: The construction of the time domain difference coefficient includes: demodulating the control signal sent by the concentrator and the control signal received by the terminal street lamp, sampling and processing the demodulated signals respectively, constructing a sending sequence and a receiving sequence, and counting the absolute difference in skewness between the sending sequence and the receiving sequence as the time domain difference coefficient, where the terminal street lamp is the street lamp farthest from the concentrator.

4. The power line carrier signal transmission method for a DC lighting system according to claim 3, characterized in that: The construction of the frequency domain difference coefficient includes: performing frequency domain transformation on the sending sequence and the receiving sequence, respectively obtaining the spectrum entropy of the two frequency domain signals after the frequency domain transformation of the sending sequence and the receiving sequence, and taking the absolute difference between the two spectrum entropies as the frequency domain difference coefficient.

5. The power line carrier signal transmission method for a DC lighting system according to claim 1, characterized in that: The acquisition of the best routing forwarding path of each concentrator includes: According to the signal influence index and noise interference index between any two connected nodes in the graph model, the pheromone parameters in the ant colony algorithm are constructed, and the ant colony algorithm is used to obtain the optimal routing forwarding path in the graph model, where the objective function is: Y = min (T + K); where Y is the objective function value; T is the number of routing forwardings during the signal transmission process; K is the overall damage index of signal transmission; The constraints are: {V(i,j)≤t,i,j∈N}; where N is the number of nodes in the graph model; t represents the preset communication hop count; V(i,j) represents the communication hop count between the i-th and j-th nodes in the graph model, where if nodes i and j are adjacent, the communication hop count between nodes i and j is 1; if node i is to node j and node j is to node k, the communication hop count between nodes i and k is 2, and so on.

6. The power line carrier signal transmission method for a DC lighting system according to claim 5, characterized in that: In the process of searching the best routing forwarding path by using the ant colony algorithm, the reciprocal of the sum of the signal influence index and the noise interference index between any two connected nodes is used as the pheromone of the edge between any two connected nodes.

7. A power line carrier signal transmission device for a DC lighting system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

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