A time synchronization system and method for wireless sensors of power Internet of Things based on multi-layer grading

Abstract

The present invention discloses a time synchronization system for wireless sensors of an electric power Internet of Things based on multi-layer grading, which comprises: a root wireless sensor, which is configured to send a time synchronization start message outward; n secondary root wireless sensors, which receive the time synchronization start message sent by the root wireless sensor; wherein each secondary root wireless sensor performs a two-way message exchange with the root wireless sensor after receiving the time synchronization start message to perform time synchronization; n groups of branch wireless sensors, which correspond to the n secondary root wireless sensors respectively, wherein each group of branch wireless sensors is configured to perform time synchronization with the corresponding secondary root wireless sensor using a beacon algorithm. The present invention also discloses a time synchronization method for wireless sensors of an electric power Internet of Things based on multi-layer grading. The time synchronization system and method for wireless sensors of an electric power Internet of Things not only meet the requirements of low power consumption, but also ensure the high time synchronization accuracy of wireless devices of the electric power Internet of Things.

Description

Technical Field

[0001] The present invention relates to a time synchronization system and method, and in particular to a sensor time synchronization system and method. Background Art

[0002] In recent years, with the rapid development of science and technology, the construction of the power Internet of Things has also been steadily advancing. As a key hub for integrating multi-source information such as power grid information, user information, and external information, wireless sensors are gradually receiving attention for their related applications and research.

[0003] In actual application, many wireless sensors in the power Internet of Things need to adopt a unified time base and accurate time marking to ensure efficient information integration and application and guarantee the quality of information data. At the same time, the monitoring and control of the power Internet of Things is not limited to local, but also to cross-regional wide-area measurement and wide-area protection. Various advanced applications supporting smart grids require the cross-sectional data of the entire power grid as the application basis, which requires that the data collection time corresponding to the relevant primary equipment is accurately synchronized. This method of unifying the time base of wireless sensors in the region can be expressed as a time synchronization method.

[0004] At present, the conventional time synchronization method used in the power system network of the prior art is generally to deploy time synchronization systems in the control center, substation, and power plant respectively, and use these time synchronization systems to ensure that the time used by the equipment in each area is synchronized.

[0005] When using this time synchronization method in the prior art for time synchronization, the accuracy of synchronization depends on the correctness of each link of time transmission, and there is a large synchronization error. In addition, this time synchronization method does not take into account the low power consumption requirements of power Internet of Things devices, and its consumption in the time synchronization process is too large and the cost is too high.

[0006] Based on this, in view of the defects and shortcomings of the prior art, the present invention hopes to obtain a multi-layer hierarchical power Internet of Things wireless sensor time synchronization system and method, which can ensure the time synchronization of the power Internet of Things wireless devices while meeting the requirements of low power consumption. Summary of the invention

[0007] One of the purposes of the present invention is to provide a multi-layer hierarchical electric power Internet of Things wireless sensor time synchronization system, which can ensure the time synchronization of electric power Internet of Things wireless devices while meeting low power consumption. It has better synchronization accuracy and can achieve a good balance between synchronization accuracy and algorithm power consumption. It can be effectively applied in the field of electric power Internet of Things and has good application prospects.

[0008] Based on the above objectives, the present invention proposes a multi-layer hierarchical power Internet of Things wireless sensor time synchronization system, which includes:

[0009] A root wireless sensor, which is configured to send a time synchronization start message outward;

[0010] n secondary root wireless sensors, which receive the time synchronization start message sent by the root wireless sensor; each secondary root wireless sensor performs a two-way message exchange with the root wireless sensor after receiving the time synchronization start message to perform time synchronization;

[0011] n groups of branch wireless sensors respectively correspond to the n secondary root wireless sensors, wherein each group of branch wireless sensors includes a plurality of branch wireless sensors, wherein each group of branch wireless sensors is configured to use a beacon algorithm for time synchronization with the corresponding secondary root wireless sensor.

[0012] In the above technical solution of the present invention, the present invention proposes a multi-layer hierarchical power Internet of Things wireless sensor time synchronization system, which may include: a root wireless sensor, n sub-root wireless sensors and n groups of branch wireless sensors.

[0013] In the present invention, after receiving the time synchronization start message, each secondary root wireless sensor exchanges two-way messages with the root wireless sensor for time synchronization; each group of branch wireless sensors is configured to use the beacon algorithm for time synchronization with its corresponding secondary root wireless sensor, and its synchronization error is low and the power consumption is not high, so it has very good application prospects.

[0014] Furthermore, in the multi-layer hierarchical power Internet of Things wireless sensor time synchronization system described in the present invention, the secondary root wireless sensor and the root wireless sensor perform two-way message exchange to perform time synchronization, wherein:

[0015] The secondary root wireless sensor calculates the time deviation Δ between it and the root wireless sensor;

[0016] The secondary root wireless sensor adds the calculated time deviation Δ to the local time to adjust and synchronize its local time to the time of the root wireless sensor.

[0017] Furthermore, in the multi-layer hierarchical power Internet of Things wireless sensor time synchronization system described in the present invention, the time deviation Δ is calculated based on the following formula:

[0018]

[0019]

[0020] Among them, at time T1, the secondary root wireless sensor sends a message composed of its own time information T1 to the root wireless sensor. The root wireless sensor receives the message at time T2 and records the receiving time T2, T2 = (T1 + d + Δ). At time T3, the root wireless sensor composes a message composed of T1, T2 and T3 information and sends it to the secondary root wireless sensor. The secondary root wireless sensor records the receiving time T4, T4 = (T3 + d - Δ), where d represents the delay of message propagation, including the transmission time and propagation time of the message.

[0021] Furthermore, in the multi-layer hierarchical power Internet of Things wireless sensor time synchronization system described in the present invention, the wireless sensor and the corresponding secondary root wireless sensor use a beacon algorithm for time synchronization, wherein:

[0022] The secondary wireless sensor sends a synchronization signal broadcast outward;

[0023] The branch wireless sensors that receive the synchronization signal broadcast exchange and compare the time when the synchronization signal broadcast arrives locally to perform time synchronization;

[0024] After receiving the time information of other branch wireless sensors, the branch wireless sensor adjusts its own clock through the offset matrix.

[0025] Furthermore, in the multi-layer hierarchical power Internet of Things wireless sensor time synchronization system described in the present invention, the offset matrix is ​​constructed as follows:

[0026]

[0027] Where offset[i, j] represents the time difference between branch wireless sensor i and branch wireless sensor j that should be adjusted, m is the number of message packets sent by the secondary root wireless sensor, n is the number of secondary root wireless sensors, T ik is the local time when branch wireless sensor i receives the synchronization signal broadcast k, T jk is the local time when branch wireless sensor j receives the synchronization signal broadcast k.

[0028] Furthermore, in the hierarchical broadcast-based power Internet of Things wireless sensor time synchronization system of the present invention, the secondary root wireless sensor adjusts its own clock through an offset matrix, and the offset matrix is ​​constructed as follows:

[0029]

[0030] Where offset[i, j] represents the time difference between the secondary wireless sensor i and the secondary wireless sensor j that should be adjusted, m is the number of message packets sent by the secondary wireless sensor, n is the number of secondary wireless sensors, Tik is the local time when the secondary wireless sensor i receives the synchronization signal broadcast k, T jk is the local time when the secondary wireless sensor j receives the synchronization signal broadcast k.

[0031] Correspondingly, another object of the present invention is to provide a time synchronization method for wireless sensors of the power Internet of Things based on multi-layer grading. The time synchronization method for wireless sensors of the power Internet of Things can ensure the time synchronization of wireless devices of the power Internet of Things while meeting low power consumption. The synchronization accuracy is relatively good and a good balance can be achieved between synchronization accuracy and algorithm power consumption. It can be effectively applied in the field of the power Internet of Things and has good application prospects.

[0032] Based on the above purpose, the present invention also proposes a time synchronization method for wireless sensors of power Internet of Things based on hierarchical broadcasting, which is implemented based on a time synchronization system for wireless sensors of power Internet of Things. The time synchronization system for wireless sensors of power Internet of Things includes: a root wireless sensor, n secondary root wireless sensors and a plurality of branch wireless sensors; the time synchronization method for wireless sensors of power Internet of Things includes the steps of:

[0033] (1) The root wireless sensor sends a time synchronization start message to the outside;

[0034] (2) After receiving the time synchronization start message, the n secondary root wireless sensors exchange bidirectional messages with the root wireless sensor to achieve time synchronization;

[0035] (3) Each sub-root wireless sensor sends a hierarchical start message containing hierarchical information to a number of branch wireless sensors, so as to divide all branch wireless sensors into n levels. The n groups of branch wireless sensors that have completed the hierarchical process can communicate with the sub-root wireless sensors corresponding to their levels.

[0036] (4) Each of the n groups of branch wireless sensors is synchronized with its corresponding secondary root wireless sensor using a beacon algorithm.

[0037] Furthermore, in the method for time synchronization of wireless sensors of the power Internet of Things based on hierarchical broadcasting described in the present invention, step (2) includes:

[0038] The secondary root wireless sensor calculates the time deviation Δ between it and the root wireless sensor;

[0039] The secondary root wireless sensor adds the calculated time deviation Δ to the local time to adjust and synchronize its local time to the time of the root wireless sensor.

[0040] Furthermore, in the time synchronization method for wireless sensors of the power Internet of Things based on hierarchical broadcasting described in the present invention, the time deviation Δ is calculated based on the following formula:

[0041]

[0042]

[0043] Among them, at time T1, the secondary root wireless sensor sends a message composed of its own time information T1 to the root wireless sensor. The root wireless sensor receives the message at time T2 and records the receiving time T2, T2 = (T1 + d + Δ). At time T3, the root wireless sensor composes a message composed of T1, T2 and T3 information and sends it to the secondary root wireless sensor. The secondary root wireless sensor records the receiving time T4, T4 = (T3 + d - Δ), where d represents the delay of message propagation, including the transmission time and propagation time of the message.

[0044] Furthermore, in the method for time synchronization of wireless sensors of the power Internet of Things based on hierarchical broadcasting described in the present invention, in step (3), each sub-root wireless sensor serves as the root of its own hierarchy and divides itself into hierarchies; the hierarchical startup message sent by each sub-root wireless sensor contains its own hierarchy information; all branch wireless sensors that receive the hierarchical startup message sent by the sub-root wireless sensor of this hierarchy set their own hierarchy to this hierarchy, write their own hierarchy information into the message and send it out; each branch wireless sensor performs the hierarchy in turn in this way until the end.

[0045] Furthermore, in the method for time synchronization of wireless sensors of the power Internet of Things based on hierarchical broadcasting described in the present invention, step (4) includes:

[0046] The secondary wireless sensor sends a synchronization signal broadcast outward;

[0047] The branch wireless sensors at the same level that receive the synchronization signal broadcast exchange and compare the time when the synchronization signal broadcast arrives locally to perform time synchronization;

[0048] After receiving the time information of other branch wireless sensors, the branch wireless sensor adjusts its own clock through the offset matrix.

[0049] Furthermore, in the time synchronization method for wireless sensors of the power Internet of Things based on hierarchical broadcasting described in the present invention, the offset matrix is ​​constructed as follows:

[0050]

[0051] Where offset[i, j] represents the time difference between branch wireless sensor i and branch wireless sensor j that should be adjusted, m is the number of message packets sent by the secondary root wireless sensor, n is the number of secondary root wireless sensors, T ikis the local time when branch wireless sensor i receives the synchronization signal broadcast k, T jk is the local time when branch wireless sensor j receives the synchronization signal broadcast k.

[0052] Compared with the prior art, the multi-layer hierarchical power Internet of Things wireless sensor time synchronization method and system described in the present invention has the following advantages and beneficial effects:

[0053] The multi-layer hierarchical electric power Internet of Things wireless sensor time synchronization method and system described in the present invention overcome the deficiencies in the prior art, especially the problems of large synchronization error and high cost in the prior art methods.

[0054] In the present invention, the time synchronization method of the wireless sensor of the power Internet of Things based on hierarchical broadcasting described in the present invention can ensure the time synchronization of the wireless device of the power Internet of Things while meeting the low power consumption. The time synchronization method of the wireless sensor of the power Internet of Things can control the time synchronization of the secondary root wireless sensor and the root wireless sensor by using a two-way message exchange method; the method using the beacon algorithm can control the time synchronization of each group of branch wireless sensors and their corresponding secondary root wireless sensors, and the synchronization accuracy is better, and a good balance can be achieved between the synchronization accuracy and the algorithm power consumption, and it can be effectively applied to the field of the power Internet of Things and has a good application prospect.

[0055] Correspondingly, the multi-layer hierarchical electric power Internet of Things wireless sensor time synchronization system described in the present invention can be used to implement the above-mentioned electric power Internet of Things wireless sensor time synchronization method of the present invention, which also has the above-mentioned advantages and beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 The schematic diagram of hierarchical broadcast synchronization time of the power Internet of Things wireless sensor time synchronization method based on hierarchical broadcasting described in the present invention is schematically shown in one implementation manner.

[0057] Figure 2 A time synchronization message model is schematically shown.

[0058] Figure 3 The schematic diagram shows the principle diagram of the root sensor of the present invention performing two-way message exchange with each secondary root wireless sensor and completing time synchronization.

[0059] Figure 4 The difference in synchronization accuracy when performing time synchronization simulation using the hierarchical broadcast-based wireless sensor time synchronization method for the power Internet of Things described in the present invention and the RBS time synchronization algorithm and TPSN time synchronization algorithm in the prior art is schematically shown.

[0060] Figure 5 The power consumption analysis when performing time synchronization simulation using the hierarchical broadcast-based wireless sensor time synchronization method for the power Internet of Things described in the present invention and the RBS time synchronization algorithm and TPSN time synchronization algorithm in the prior art is schematically shown. DETAILED DESCRIPTION

[0061] The following will further explain and illustrate the multi-layer hierarchical power Internet of Things wireless sensor time synchronization system and method described in the present invention in combination with the drawings in the specification and specific embodiments. However, such explanation and illustration do not constitute an improper limitation on the technical solution of the present invention.

[0062] In the present invention, the electric power Internet of Things wireless sensor time synchronization system described in the present invention can be used to implement the electric power Internet of Things wireless sensor time synchronization method described in the present invention.

[0063] Figure 1 The schematic diagram of hierarchical broadcast synchronization time of the power Internet of Things wireless sensor time synchronization method based on hierarchical broadcasting described in the present invention is schematically shown in one implementation manner.

[0064] like Figure 1 As shown, in the electric power Internet of Things wireless sensor time synchronization system based on hierarchical broadcasting described in the present invention, the system may include: a root wireless sensor, n sub-root wireless sensors and n groups of branch wireless sensors.

[0065] It should be noted that Figure 1 The dashed box portion may represent two-way message exchange synchronization within the communication range of the root wireless sensor. In the present invention, the root wireless sensor may send a time synchronization start message outside within the communication range. The n secondary root wireless sensors may receive the time synchronization start message sent by the root wireless sensor, and each secondary root wireless sensor may perform two-way message exchange with the root wireless sensor after receiving the time synchronization start message to perform time synchronization.

[0066] Accordingly, Figure 1 The solid line box portion in the figure can represent beacon algorithm synchronization. In the present invention, n groups of branch wireless sensors can correspond to n secondary root wireless sensors in the matching system, wherein each secondary root wireless sensor can match a group of branch wireless sensors, and a single group of branch wireless sensors includes multiple branch wireless sensors. Each group of branch wireless sensors is configured to use the beacon algorithm for time synchronization with the corresponding secondary root wireless sensor.

[0067] It can be seen that in the present invention, the time synchronization method of the power Internet of Things wireless sensor based on hierarchical broadcasting described in the present invention may include the following steps:

[0068] (1) The root wireless sensor sends a time synchronization start message.

[0069] In the above step (1), it is first necessary to select a root wireless sensor in the power Internet of Things network. The root wireless sensor needs to send a time synchronization start message, which can perform two-way message exchange with the secondary root wireless sensor for time synchronization.

[0070] (2) After receiving the time synchronization start message, the n secondary root wireless sensors exchange bidirectional messages with the root wireless sensor to achieve time synchronization.

[0071] In the above step (2), after receiving the time synchronization start message, the n secondary root wireless sensors can calculate the time deviation Δ between themselves and the root wireless sensor. The secondary root wireless sensor can further add the calculated time deviation Δ to the local time to adjust and synchronize its local time to the time of the root wireless sensor.

[0072] (3) Each sub-root wireless sensor sends a hierarchical start message containing hierarchical information to a number of branch wireless sensors, so as to divide all branch wireless sensors into n levels. The n groups of wireless sensors that have completed the hierarchical process can communicate with the sub-root wireless sensors corresponding to their levels.

[0073] In the above step (3), the network needs to complete hierarchical classification. In the present invention, all sub-root wireless sensors serve as the root of their own hierarchy and divide themselves into hierarchies. Each sub-root wireless sensor can send a hierarchical startup message to the network through a broadcast algorithm.

[0074] Using the hierarchical startup message sent by the sub-root wireless sensor, each hierarchical startup message sent by the sub-root wireless sensor contains its own hierarchical information. According to the message content, the branch wireless sensors in the entire power Internet of Things can be hierarchically classified. All wireless sensors that receive the broadcast message of the 1st-level sub-root wireless sensor can set their own level to 1, write their own level information into the message, and resend it to the network. For example, after a branch wireless sensor in the network receives the broadcast message of the mth-level branch wireless sensor, it can set its own level to m+1. Each branch wireless sensor in the network is classified in this way until the classification is completed. The classification results can be as follows: Figure 1 The solid box shown.

[0075] (4) Each of the n groups of branch wireless sensors is synchronized with its corresponding secondary root wireless sensor using a beacon algorithm.

[0076] After the grading stage is completed, each branch wireless sensor is at a certain level in the hierarchy. For example, the branch wireless sensor at level 3 (or "group") can use the beacon algorithm to synchronize time with the secondary root wireless sensor at level 3.

[0077] In the above step (4), the basic idea of ​​the beacon algorithm is to use the secondary root wireless sensor in the same level to broadcast the synchronization signal. The secondary root wireless sensor can send the synchronization signal broadcast outward, and the branch wireless sensors that receive the synchronization signal broadcast exchange and compare the time when the synchronization signal broadcast arrives locally to perform time synchronization.

[0078] First, at a certain level in the network, according to the set sub-root wireless sensor, the sub-root wireless sensor has completed time synchronization, so it only needs to send a synchronization signal broadcast, which contains its own time information; after the branch wireless sensor receives the time information of other branch wireless sensors, it records the arrival time of the synchronization signal broadcast according to its own local time; then the branch wireless sensors to be synchronized send their own recorded time to the network respectively, and receive the synchronization signal broadcast sent by other branch wireless sensors. By comparing and processing the time information in the synchronization signal broadcast sent by each branch wireless sensor, each branch wireless sensor adjusts its own clock to the average clock to complete the synchronization.

[0079] When the branch wireless sensor receives the time information of other wireless sensors, the secondary root wireless sensor can adjust its own clock through the offset matrix. The offset matrix can be constructed as follows:

[0080]

[0081] Wherein, offset[i,j] represents the time difference between wireless sensor i and wireless sensor j that should be adjusted, m is the number of message packets sent by the secondary wireless sensor, n is the number of secondary wireless sensors, T ik is the local time when branch wireless sensor i receives the synchronization signal broadcast k, T jk is the local time when branch wireless sensor j receives the synchronization signal broadcast k.

[0082] It can be seen that in the present invention, since the time of n secondary root wireless sensors has been synchronized, the corresponding n groups of branch wireless sensors can be synchronized through the above technical solution, and finally complete the time synchronization of the entire network.

[0083] It should be noted that in order to achieve time synchronization, sensors often need to communicate with each other to exchange their respective time information, which can be called messages. The exchange of messages involves many links, such as information encapsulation, waiting for the channel to be idle, etc. Each link will produce a delay of varying degrees, and the delay is often uncertain. The specific division of message transmission delay can be as follows Figure 2 shown.

[0084] Figure 2 A time synchronization message model is schematically shown.

[0085] like Figure 2 As shown, the send time refers to the time required for the sender to generate a message and transfer it to the MAC layer. In the present invention, the send time can represent: the time it takes for the sensor to send the information packet to the sender after completing the time information packaging.

[0086] Correspondingly, the access time refers to the time the sending sensor waits for sending after completing the sending preparation. Since the sensor can only send one message at the same time, if the sensor is sending other message packets, it must wait for the sensor to be idle, that is, the "waiting for access" time.

[0087] Transmission time refers to the time it takes for a sensor to send a time packet. The length of the packet is determined as L (bits). If the data rate of the sensor is R (bits / s), the transmission time is L / R (s). It can be seen that the transmission time is related to the packet length and the transmission speed.

[0088] Propagation Time refers to the time it takes for an electromagnetic wave to travel between two sensors. Since electromagnetic waves travel at the speed of light, this time can often be ignored.

[0089] Reception Time refers to the reception time of the receiving sensor, which corresponds to the transmission time and the time can be determined.

[0090] Receive processing time (Receive Time) refers to the time taken by the receiving sensor to transmit the message to the upper-layer application after receiving the information sent by other sensors. It depends on the current load of the processor, etc., corresponding to the sending time, and the length of time is uncertain.

[0091] It should be noted that, in the present invention, both the branch wireless sensors and the secondary root wireless sensors used in the electric power Internet of Things can be defined as nodes.

[0092] The clock model of a node can quantitatively explain the time variation of a node by mathematical formula, which can be divided into time deviation and frequency drift. The existing time synchronization protocols are all trying to solve the time synchronization problem between nodes from these two aspects.

[0093] Node local clock: Generally speaking, a node determines its local time by counting the number of interruptions of its own crystal oscillator. Therefore, the local clock reading of node i at time t can be expressed as:

[0094]

[0095] Among them, T i (t) is the local time of node i at time t, t is a real time variable, t0 represents the physical moment when timing starts, k is a constant that depends on the characteristics of the crystal itself, w(t) is the angular frequency of the crystal oscillator at node i, T i (t0) represents the local clock reading of node i at time t0.

[0096] Logical clock of the node: In order to complete the conversion and adjustment between different clocks, a logical clock can be constructed to construct the conversion relationship between two clocks. It can be seen that the logical clock of node i in the network at time t can be expressed as:

[0097] C i (t) = a i ·T i (t)+b i (3)

[0098] Among them, T i (t) is the local clock reading of node i at time t; a i is the frequency correction coefficient of node i; b i is the initial phase correction coefficient of node i.

[0099] It should be noted that T i (t) represents the time calculated by node i based on its own crystal, which is often asynchronous. In order to synchronize any two nodes i and j, it is necessary to construct corresponding logical clocks so that the two clocks have a connection in phase and frequency, and then synchronization can be achieved by adjusting one of the clocks.

[0100] Therefore, in the power Internet of Things, the clock logic relationship between the two nodes i and j can be expressed as:

[0101] C j (t) = a ij C i (t)+b ij (4)

[0102] Among them, C j (t) is the logical clock of node j in the network at time t; (relative drift); (relative offset); a i represents the frequency correction coefficient of node i; a j represents the frequency correction coefficient of node j; b i represents the initial phase correction coefficient of node i; b j represents the initial phase correction coefficient of node j; i , b i Set the corresponding a ij , b ij Thus, a logical clock is constructed to achieve time synchronization between node i and node j.

[0103] Figure 3 The schematic diagram shows the principle diagram of the root sensor of the present invention performing two-way message exchange with each secondary root wireless sensor and completing time synchronization.

[0104] In the present invention, the secondary root wireless sensor of the present invention can calculate the time deviation Δ between itself and the root wireless sensor, and add the calculated time deviation Δ to the local time to adjust and synchronize its local time to the time of the root wireless sensor.

[0105] like Figure 3 As shown, in the present invention, at time T1, the secondary root wireless sensor forms a message with its own time information T1 and sends it to the root wireless sensor. The root wireless sensor receives the message at time T2 and records the receiving time T2, T2=(T1+d+Δ); at time T3, the root wireless sensor forms a message with T1, T2 and T3 information and sends it to the secondary root wireless sensor. The secondary root wireless sensor records the receiving time T4, T4=(T3+d-Δ), where d represents the delay of message propagation, including the transmission time and propagation time of the message.

[0106] Therefore, it can be deduced that the time deviation Δ can be calculated by the following formula (5), and the message propagation delay d can be calculated by the following formula (6):

[0107]

[0108]

[0109] Accordingly, in the multi-layer hierarchical power Internet of Things wireless sensor time synchronization method described in the present invention, the secondary root wireless sensor to be time synchronized can use the above formula (5) to calculate the time deviation Δ between it and the root wireless sensor. The secondary root wireless sensor can add the calculated time deviation Δ to its local time, and adjust its local time to synchronize with the time of the secondary root wireless sensor.

[0110] In the present invention, the secondary root wireless sensor performs bidirectional message exchange with the root wireless sensor, and adjusts its own time in the above manner until the time synchronization of all secondary root wireless sensors and the root wireless sensor is completed.

[0111] In order to further illustrate the superiority of the hierarchical broadcast-based power Internet of Things wireless sensor time synchronization method described in the present invention, the method of the present invention can be used to perform specific implementation tests with the RBS time synchronization algorithm and TPSN time synchronization algorithm commonly used in the prior art to compare the implementation effects of the three schemes.

[0112] In the present invention, network modeling simulation software (such as OpNet software) can be used to perform network simulation. The simulation software can be used to build models of wired and wireless networks and programmatically design network nodes and process models to change the network's own protocols. Detection needles can also be inserted into the model to obtain corresponding data during the simulation process.

[0113] During the implementation verification process, the hierarchical broadcast-based power Internet of Things wireless sensor time synchronization method described in the invention and the RBS time synchronization algorithm and TPSN time synchronization algorithm commonly used in the prior art are applied to the above-mentioned simulation model, and specific implementation tests are carried out.

[0114] Figure 4 The difference in synchronization accuracy when performing time synchronization simulation using the hierarchical broadcast-based wireless sensor time synchronization method for the power Internet of Things described in the present invention and the RBS time synchronization algorithm and TPSN time synchronization algorithm in the prior art is schematically shown.

[0115] like Figure 4 As shown, the time synchronization method of the electric power Internet of Things wireless sensor based on hierarchical broadcasting described in the present invention corresponds to curve A1; the RBS time synchronization algorithm corresponds to curve A2; and the TPSN time synchronization algorithm corresponds to curve A3.

[0116] By comparing the commonly used RBS time synchronization algorithm and TPSN time synchronization algorithm in the prior art, it can be found that the synchronization accuracy of the nodes of the RBS time synchronization algorithm is very high, and it is predicted that it can reach the level of 0.5 microseconds; the synchronization error of the TPSN algorithm is much larger than that of the RBS algorithm, and the synchronization error is about 15 microseconds in the case of a single-hop network. The accuracy obtained by the time synchronization method of the power Internet of Things wireless sensor based on hierarchical broadcasting described in the present invention is between the above two algorithms, and its synchronization error is about within 10 microseconds.

[0117] Figure 5 The power consumption analysis when performing time synchronization simulation using the hierarchical broadcast-based wireless sensor time synchronization method for the power Internet of Things described in the present invention and the RBS time synchronization algorithm and TPSN time synchronization algorithm in the prior art is schematically shown.

[0118] like Figure 5 As shown, Figure 5 The figure schematically shows the relationship between the number of nodes and the number of messages (algorithm power consumption) when three different time synchronization methods are used. The time synchronization method for wireless sensors in the power Internet of Things based on hierarchical broadcasting described in the present invention corresponds to curve B1; the RBS time synchronization algorithm corresponds to curve B2; and the TPSN time synchronization algorithm corresponds to curve B3.

[0119] Combined with reference Figure 4 and Figure 5 It can be seen that in the specific implementation process, compared with the RBS time synchronization algorithm and the TPSN time synchronization algorithm in the prior art, the power Internet of Things wireless sensor time synchronization method based on hierarchical broadcasting described in the present invention can achieve a better balance between synchronization actuarial and algorithm power consumption. It is very suitable for the power Internet of Things and has good application prospects.

[0120] From the above, it can be seen that the time synchronization method of the electric power Internet of Things wireless sensor described in the present invention can ensure the time synchronization of the electric power Internet of Things wireless devices while meeting the low power consumption requirement. The synchronization accuracy is relatively good, and a good balance can be achieved between the synchronization accuracy and the algorithm power consumption. It can be effectively applied in the field of the electric power Internet of Things and has good application prospects.

[0121] Correspondingly, the multi-layer hierarchical electric power Internet of Things wireless sensor time synchronization system described in the present invention can be used to implement the above-mentioned electric power Internet of Things wireless sensor time synchronization method of the present invention, which also has the above-mentioned advantages and beneficial effects.

[0122] It should be noted that the prior art in the protection scope of the present invention is not limited to the embodiments given in the present application documents. All prior art that does not contradict the scheme of the present invention, including but not limited to prior patent documents, prior public publications, prior public uses, etc., can be included in the protection scope of the present invention.

[0123] In addition, the combination of the various technical features in this case is not limited to the combination described in the claims of this case or the combination described in the specific embodiments. All technical features recorded in this case can be freely combined or combined in any way unless there is a contradiction between them.

[0124] It should also be noted that the above-listed embodiments are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made therewith can be directly derived or easily associated with the contents disclosed by those skilled in the art from the present invention, and all should belong to the protection scope of the present invention.

Claims

1. A multi-layer hierarchical power Internet of Things wireless sensor time synchronization system, characterized in that: include: A root wireless sensor, which is configured to send a time synchronization start message outward; n secondary root wireless sensors, which receive the time synchronization start message sent by the root wireless sensor; each secondary root wireless sensor performs a two-way message exchange with the root wireless sensor after receiving the time synchronization start message to perform time synchronization; n groups of branch wireless sensors, which correspond to the n secondary root wireless sensors respectively, wherein each group of branch wireless sensors includes a plurality of branch wireless sensors, wherein each group of branch wireless sensors is configured to use a beacon algorithm for time synchronization with the corresponding secondary root wireless sensor; The branch wireless sensor and the corresponding secondary root wireless sensor use a beacon algorithm for time synchronization, wherein: The secondary wireless sensor sends a synchronization signal broadcast outward; The branch wireless sensors that receive the synchronization signal broadcast exchange and compare the time when the synchronization signal broadcast arrives locally to perform time synchronization; After receiving the time information of other branch wireless sensors, the branch wireless sensor adjusts its own clock through the offset matrix; The offset matrix is ​​constructed as: Where offset[i,j] represents the time difference between branch wireless sensor i and branch wireless sensor j that should be adjusted, m is the number of message packets sent by the secondary root wireless sensor, n is the number of secondary root wireless sensors, T ik is the local time when branch wireless sensor i receives the synchronization signal broadcast k, T jk is the local time when branch wireless sensor j receives the synchronization signal broadcast k.

2. The multi-layer hierarchical power Internet of Things wireless sensor time synchronization system according to claim 1 is characterized in that: The secondary root wireless sensor exchanges bidirectional messages with the root wireless sensor for time synchronization, where: The secondary root wireless sensor calculates the time deviation Δ between it and the root wireless sensor; The secondary root wireless sensor adds the calculated time deviation Δ to the local time to adjust and synchronize its local time to the time of the root wireless sensor.

3. The multi-layer hierarchical power Internet of Things wireless sensor time synchronization system according to claim 2 is characterized in that: The time deviation Δ is calculated based on the following formula: Among them, at time T1, the secondary root wireless sensor sends a message composed of its own time information T1 to the root wireless sensor. The root wireless sensor receives the message at time T2 and records the receiving time T2, T2 = (T1 + d + Δ). At time T3, the root wireless sensor composes a message composed of T1, T2 and T3 information and sends it to the secondary root wireless sensor. The secondary root wireless sensor records the receiving time T4, T4 = (T3 + d - Δ), where d represents the delay of message propagation, including the transmission time and propagation time of the message.

4. A multi-layer hierarchical power Internet of Things wireless sensor time synchronization method, characterized in that: It is implemented based on a power Internet of Things wireless sensor time synchronization system, which includes: a root wireless sensor, n secondary root wireless sensors and a number of branch wireless sensors; the power Internet of Things wireless sensor time synchronization method includes the steps of: (1) The root wireless sensor sends a time synchronization start message; (2) After receiving the time synchronization start message, the n secondary root wireless sensors exchange bidirectional messages with the root wireless sensor to perform time synchronization; (3) Each sub-root wireless sensor sends a hierarchical start message containing hierarchical information to a number of branch wireless sensors, so as to divide all branch wireless sensors into n levels. The n groups of branch wireless sensors that have completed the hierarchical process can communicate with the sub-root wireless sensors corresponding to their levels. (4) Each of the n groups of branch wireless sensors is time synchronized with the corresponding secondary root wireless sensor using a beacon algorithm, which includes: The secondary wireless sensor sends a synchronization signal broadcast outward; The branch wireless sensors at the same level that receive the synchronization signal broadcast exchange and compare the time when the synchronization signal broadcast arrives locally to perform time synchronization; After receiving the time information of other branch wireless sensors, the branch wireless sensor adjusts its own clock through the offset matrix; The offset matrix is ​​constructed as: Where offset[i,j] represents the time difference between branch wireless sensor i and branch wireless sensor j that should be adjusted, m is the number of message packets sent by the secondary root wireless sensor, n is the number of secondary root wireless sensors, T ik is the local time when branch wireless sensor i receives the synchronization signal broadcast k, T jk is the local time when branch wireless sensor j receives the synchronization signal broadcast k.

5. The multi-layer hierarchical power Internet of Things wireless sensor time synchronization method according to claim 4 is characterized in that: Wherein step (2) comprises: The secondary root wireless sensor calculates the time deviation Δ between it and the root wireless sensor; The secondary root wireless sensor adds the calculated time deviation Δ to the local time to adjust and synchronize its local time to the time of the root wireless sensor.

6. The multi-layer hierarchical power Internet of Things wireless sensor time synchronization method according to claim 5, characterized in that: The time deviation Δ is calculated based on the following formula: Among them, at time T1, the secondary root wireless sensor sends a message composed of its own time information T1 to the root wireless sensor. The root wireless sensor receives the message at time T2 and records the receiving time T2, T2 = (T1 + d + Δ). At time T3, the root wireless sensor composes a message composed of T1, T2 and T3 information and sends it to the secondary root wireless sensor. The secondary root wireless sensor records the receiving time T4, T4 = (T3 + d - Δ), where d represents the delay of message propagation, including the transmission time and propagation time of the message.

7. The multi-layer hierarchical power Internet of Things wireless sensor time synchronization method according to claim 4 is characterized in that: In step (3), each sub-root wireless sensor acts as the root of its own hierarchy and divides itself into hierarchies; the hierarchical startup message sent by each sub-root wireless sensor contains its own hierarchical information; all branch wireless sensors that receive the hierarchical startup message sent by the sub-root wireless sensor of this level set their own level to this level, write their own hierarchical information into the message and send it out; each branch wireless sensor is hierarchical in this way until the end.

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