A method and system for low-voltage phasor measurement based on field clock synchronization

Abstract

This invention discloses a low-voltage distribution area phasor measurement method and system based on field clock synchronization. The method includes acquiring voltage and current waveform data from slave nodes on power lines; performing time-domain or frequency-domain adjustments on the voltage and current waveform data to phase-shift the data and obtain phase-shifted signals; applying a windowing operation to the phase-shifted signals and performing phase compensation to obtain phasor data; and uploading the phasor data to the concentrator. The low-voltage distribution area phasor measurement method based on field clock synchronization described in this invention can synchronously acquire and calculate voltage and current waveform data collected by the acquisition unit. The combination of the concentrator and the acquisition unit achieves high-precision clock synchronization across the entire network, enabling large-scale deployment in low-voltage distribution areas. It is highly economical and can guarantee real-time calculation requirements.

Description

Technical Field

[0001] This invention relates to the field of phasor measurement technology, and in particular to a low-voltage phasor measurement method and system based on field clock synchronization. Background Technology

[0002] Synchronous phasor measurement unit (PMU) technology is a core means for dynamic monitoring of the power grid, rapid fault location, real-time analysis of network topology, accurate quantification of line losses, and efficient identification of electricity theft in modern power systems. Because it can provide high-precision voltage and current phasor data with microsecond-level time synchronization across the entire network, it is regarded as the core sensing layer technology of smart grids and lays an important foundation for improving the stability, security, and efficiency of the power grid.

[0003] Currently, existing PMU devices require strict synchronous sampling and real-time computation. These devices primarily rely on multi-channel independent high-precision analog-to-digital converters (ADCs) and high-performance digital signal processors (DSPs). The high cost of these components, coupled with the overhead of the associated high-precision clock and data processing units, results in an overall expensive PMU device. Furthermore, in addition to their high cost, achieving microsecond-level time synchronization requires overcoming several systemic challenges, including the inherent delay introduced by anti-aliasing filters at the hardware level, the cumulative effect of small data sampling time offsets, and the optimization of anti-interference algorithms in complex environments.

[0004] It is known that relying on PMU devices with multi-channel independent high-precision analog-to-digital converters (ADCs) and high-performance digital signal processors (DSPs) to achieve synchronous sampling and real-time calculation is costly, consumes a lot of power, and has extremely strict requirements for clock synchronization accuracy. It is difficult to meet the economic and energy efficiency requirements of large-scale deployment in low-voltage distribution areas, while increasing system complexity and maintenance difficulty. Summary of the Invention

[0005] The purpose of this invention is to provide a low-voltage distribution area phasor measurement method and system based on field clock synchronization, so as to solve the technical problem that the existing PMU devices are difficult to meet the economic and energy efficiency requirements when deploying low-voltage distribution areas on a large scale.

[0006] The preferred technical solutions among the many technical solutions provided by this invention can produce a variety of technical effects, which are described in detail below.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a low-voltage phasor measurement method based on field clock synchronization, comprising:

[0009] The voltage waveform data and current waveform data of the slave nodes on the power line are acquired. There are multiple slave nodes. The voltage waveform data and the current waveform data are acquired by the corresponding data acquisition devices set at the slave nodes. The data acquisition devices at the multiple slave nodes are synchronized with the concentrator at the master node in time and interact with the data.

[0010] The voltage waveform data and the current waveform data are adjusted in the time domain or frequency domain to perform phase shifting processing on the voltage waveform data and the current waveform data, and the phase-shifted signal is obtained.

[0011] The phase-shifted signal is windowed and phase compensation is performed to obtain phasor data;

[0012] The phasor data is uploaded to the concentrator.

[0013] Optionally, the voltage waveform data and the current waveform data are subjected to time-domain adjustment to perform phase-shifting processing on the voltage waveform data and the current waveform data, and to obtain a phase-shifted signal, including:

[0014] Construct a signal model;

[0015] In the signal model, offline coefficient pre-calculation is performed on the voltage waveform data and the current waveform data to generate phase shift coefficients;

[0016] The phase-shifting coefficients are convolved in real time using an online sliding window, and sliding compensation is performed to obtain the phase-shifted signal.

[0017] Optionally, the step of performing offline coefficient pre-calculation on the voltage waveform data and the current waveform data in the signal model to generate phase shift coefficients includes:

[0018] Construct the Vandermonde matrix, the expression of which is:

[0019] ;

[0020] Where L is the sampling window length and M is the polynomial order;

[0021] Calculate the normal equation coefficient matrix of the Vandermonde matrix: ;

[0022] Set a target phase point and construct a target vector based on the target phase point;

[0023] Calculate the coefficient vector based on the normal equation coefficient matrix and the target vector;

[0024] The phase shift coefficients are generated based on the coefficient vector.

[0025] Optionally, the construction of the signal model includes:

[0026] Set system variables;

[0027] Configure signal parameters;

[0028] Construct a signal model based on the system variables and the signal parameters.

[0029] Optionally, frequency domain adjustment is performed on the voltage waveform data and the current waveform data to perform phase shifting processing on the voltage waveform data and the current waveform data, and to obtain the phase-shifted signal, including:

[0030] Perform Fourier transform on the voltage waveform data and the current waveform data to obtain the signal spectrum;

[0031] Modify the phase component in the signal spectrum, wherein the formula for modifying the phase component is: Output phase = Original phase + Fixed offset + Data synchronization phase shift;

[0032] Based on the phase components, phasors are extracted, the voltage waveform data and the current waveform data are aligned, and the phase-shifted signal is obtained.

[0033] Optionally, the step of windowing the phase-shifted signal and performing phase compensation to obtain phasor data includes:

[0034] A window function is applied to the phase-shifted signal to obtain a windowed discrete signal;

[0035] Perform a Fourier transform on the windowed discrete signal to obtain the complex spectrum;

[0036] Phase compensation is performed on the complex spectrum based on the group delay characteristics of the window function to obtain the corrected spectrum;

[0037] Precise phasor values ​​are extracted from the corrected spectrum to obtain phasor data.

[0038] Secondly, the present invention also provides a low-voltage phasor measurement system based on field clock synchronization for use in the low-voltage phasor measurement method based on field clock synchronization described above. The system includes a concentrator set at the master node and acquisition units set at multiple slave nodes. The acquisition units perform time synchronization and data interaction with the concentrator.

[0039] Optionally, the concentrator includes a CCO terminal, and the collector includes an STA terminal, the collector being connected to the concentrator via the STA terminal and the CCO terminal;

[0040] The concentrator and the collector share a network reference time through the local communication network, enabling the concentrator and the collector to synchronize their time across the entire network.

[0041] Optionally, the data acquisition unit further includes a measurement unit connected to the STA terminal, which interacts with the CCO terminal of the concentrator via the STA terminal; the measurement unit is also used to perform edge computing on the voltage waveform data and current waveform data.

[0042] Thirdly, the present invention also provides a computer-readable storage medium storing a computer program, which, when executed, implements the aforementioned low-voltage phasor measurement method based on field clock synchronization.

[0043] Implementing one of the above-described technical solutions of the present invention has the following advantages or beneficial effects:

[0044] When implementing the low-voltage phasor measurement method based on field clock synchronization described in this invention, firstly, voltage and current waveform data of slave nodes on the power line are acquired. Multiple slave nodes are configured, and the voltage and current waveform data are acquired by corresponding data acquisition units located at each slave node. All data acquisition units at the multiple slave nodes synchronize with and interact with the concentrator. Precise time synchronization and data interaction between the data acquisition units at the multiple slave nodes and the concentrator ensure the synchronization of data acquisition among the multiple slave nodes, avoiding timing errors. Subsequently, the voltage and current waveform data are adjusted in the time domain or frequency domain to perform phase shifting processing, thereby changing the phase of the signal and obtaining a phase-shifted signal, which facilitates further processing of the voltage and current waveform data.

[0045] Then, windowing is applied to the phase-shifted signal, and phase compensation is performed to obtain phasor data. Finally, the obtained phasor data is uploaded to the concentrator for data aggregation.

[0046] The low-voltage distribution area phasor measurement method based on field clock synchronization described in this embodiment can synchronously acquire and calculate voltage and current waveform data collected by the acquisition device. The concentrator and acquisition device in this embodiment are combined to achieve high-precision clock synchronization of the entire network, and can be deployed on a large scale in low-voltage distribution areas. It is highly economical and solves the dual problems of hardware cost and synchronization accuracy. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0048] Figure 1 This is a flowchart illustrating Embodiment 1 of the present invention;

[0049] Figure 2 This is a schematic diagram illustrating the process of network-wide synchronization and data collection by the collector and concentrator in Embodiment 1 of the present invention;

[0050] Figure 3 This is a waveform sampling diagram of the measurement unit in the data acquisition device in Embodiment 1 of the present invention for acquiring sampled data;

[0051] Figure 4 This is a schematic diagram of the structure of Embodiment 2 of the present invention. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of the present invention clearer, various exemplary embodiments described below will be referenced to the accompanying drawings, which form part of the exemplary embodiments, illustrating various exemplary embodiments that may be used to implement the present invention. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. It should be understood that they are merely examples of processes, methods, and apparatuses consistent with some aspects of the present invention disclosed as detailed in the appended claims, and other embodiments may be used, or structural and functional modifications may be made to the embodiments listed herein without departing from the scope and spirit of the present invention.

[0053] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the referred element must have a specific orientation, or be constructed and operated in a specific orientation. The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. The term "a plurality" means two or more. The terms "connected" and "linked" should be interpreted broadly, for example, they can refer to fixed connections, detachable connections, integral connections, mechanical connections, electrical connections, communication connections, direct connections, indirect connections through an intermediate medium, and can refer to the internal communication of two elements or the interaction relationship between two elements. The term "and / or" includes any and all combinations of one or more of the related listed items. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0054] To illustrate the technical solution described in this invention, specific embodiments are described below, showing only the parts related to the embodiments of this invention.

[0055] Example 1:

[0056] like Figure 1 As shown, this invention provides a low-voltage phasor measurement method based on field clock synchronization, comprising:

[0057] S100. Acquire voltage waveform data and current waveform data of slave nodes on the power line. There are multiple slave nodes. The voltage waveform data and current waveform data are acquired by the corresponding acquisition devices set at the slave nodes. The acquisition devices at the multiple slave nodes synchronize time and interact with the concentrator at the master node.

[0058] S200: Perform time-domain or frequency-domain adjustment on the voltage waveform data and current waveform data to phase-shift the voltage waveform data and current waveform data, and obtain the phase-shifted signal.

[0059] S300: Window the phase-shifted signal and perform phase compensation to obtain phasor data;

[0060] S400: Upload phasor data to the concentrator.

[0061] Specifically, when implementing the low-voltage phasor measurement method based on field clock synchronization described in this embodiment, firstly, voltage and current waveform data of the slave nodes on the power line are acquired. Multiple slave nodes are configured, and the voltage and current waveform data are acquired by corresponding data acquisition units located at each slave node. All data acquisition units at the slave nodes synchronize with and interact with the concentrator. Precise time synchronization and data interaction between the data acquisition units at the multiple slave nodes and the concentrator ensure the synchronization of data acquisition among the multiple slave nodes, avoiding timing errors. Subsequently, the voltage and current waveform data are adjusted in the time domain or frequency domain to perform phase shifting processing, thereby changing the phase of the signal and obtaining a phase-shifted signal, which facilitates further processing of the voltage and current waveform data.

[0062] Then, windowing is applied to the phase-shifted signal, and phase compensation is performed to obtain phasor data. Finally, the obtained phasor data is uploaded to the concentrator for data aggregation.

[0063] The low-voltage distribution area phasor measurement method based on field clock synchronization described in this embodiment can synchronously acquire and calculate voltage and current waveform data collected by the acquisition device. The concentrator and acquisition device in this embodiment are combined to achieve high-precision clock synchronization of the entire network, and can be deployed on a large scale in low-voltage distribution areas. It is highly economical and solves the dual problems of hardware cost and synchronization accuracy.

[0064] Below, we will combine Figure 1 The low-voltage phasor measurement method based on field clock synchronization described in this embodiment is explained in detail.

[0065] First, step S100 is executed to acquire voltage waveform data and current waveform data of the slave nodes on the power line. There are multiple slave nodes, and the voltage waveform data and current waveform data are acquired by the corresponding acquisition devices set at the slave nodes. The acquisition devices at the multiple slave nodes synchronize time and interact with the concentrator at the master node.

[0066] Specifically, the local communication network in this embodiment includes multiple nodes, specifically one master node and multiple slave nodes. A concentrator is located at the master node, and each of the slave nodes has a data collector. The multiple data collectors are connected to the concentrator, and they exchange data with the concentrator for time synchronization.

[0067] Multiple collectors at the slave nodes synchronize their time with the concentrator at the master node. This includes: the concentrator at the master node is equipped with a CCO terminal, and the collectors at the multiple slave nodes are equipped with STA terminals. The collectors are connected to the concentrator through the STA terminals and CCO terminals. The master node and multiple slave nodes share the network reference time through the local communication network, thereby synchronizing the time of the master node and multiple slave nodes across the entire network.

[0068] The master node and multiple slave nodes share a network time base (NTB) through a local communication network. Specifically, all nodes in the local communication network must synchronize with the NTB. The NTB is provided by a 25MHz clock at the master node's Control Center (CCO), which maintains this time using a 32-bit timer with an accuracy of 40 nanoseconds.

[0069] Each node in the network also maintains a 32-bit local timer (NTB_STA), with the same time precision of 40 nanoseconds. The local timer must maintain consistency with the NTB at the CCO end in terms of frequency and absolute value to ensure time synchronization across all nodes in the network, enabling orderly and accurate communication. For example, during data transmission, synchronized time ensures that each node sends and receives data at the correct time, avoiding data conflicts or loss.

[0070] More specifically, the master node and multiple slave nodes are synchronized across the entire network, where the master node is the central node and the slave nodes are multi-layered child nodes. The network time synchronization between the master and slave nodes includes the following steps: the concentrator's CCO sends two timestamped beacon frames to the STAs among the multiple first-layer slave nodes; the collector calculates the frequency deviation between the STAs and the CCO based on the two beacon frames, and calibrates the clock frequency of the STAs according to the frequency deviation; the calibration formula is: NTBTx = NTBRx - NTBDelay, where NTBTx is the sending timestamp value of the CCO, NTBRx is the receiving timestamp value of the STAs, and NTBDelay is a fixed delay; the first-layer slave nodes send proxy beacons to multiple second-layer slave nodes, and the second-layer slave nodes calibrate their own clock frequencies according to the timestamp of the proxy beacons; thus, the multiple slave nodes achieve network-wide clock frequency synchronization with the master node.

[0071] The concentrator's CCO (Concentrator Operations Center) periodically sends two timestamped beacon frames, which are received by the STA (Stationary Access Center) of the first-layer slave nodes. It's important to note that the beacon frames carry the timestamp via the BTS (Browser Time Transmission) field, broadcasting the time information in real-time to the STAs of all slave nodes in the network.

[0072] After receiving two beacon frames, the STA performs the following operations: The STA calculates the difference in timestamps between the two beacon frames to obtain the CCO's transmission timestamp value; it also calculates the time it received the two beacon frames to obtain the STA's reception timestamp value; based on the CCO's transmission timestamp value and the STA's reception timestamp value, it calculates the frequency deviation between the STA and the CCO, and calibrates the STA's clock frequency according to this frequency deviation.

[0073] The data collector calculates the difference in timestamps between the two received beacon frames to obtain the transmission timestamp value at the CCO end. The CCO's transmission timestamp value reflects the time interval between the CCO's reference clock and the transmission times of the two beacon frames. Simultaneously, the STA end records the time it receives both beacon frames locally and calculates the difference to obtain its reception timestamp value. The STA's reception timestamp value reflects the time interval between its local clock and the same time period.

[0074] By comparing and calculating the transmit timestamp value at the CCO end and the receive timestamp value at the STA end, the STA end can calculate the deviation between its local frequency and the reference clock frequency of the CCO end, i.e., the frequency deviation. Based on the frequency deviation, the STA end can adjust its local clock frequency to achieve synchronization with the clock frequency of the CCO end. Following this method, all nodes in the network can communicate and transmit data under the same time base, ensuring the normal operation of the network.

[0075] It should also be noted that when calibrating the clock frequency of the STA based on the frequency deviation, the calculation formula is: NTBTx = NTBRx - NTBDelay, where NTBTx is the transmit timestamp value of the CCO, NTBRx is the receive timestamp value of the STA, and NTBDelay is a fixed delay. Using this formula, the STA can calculate the transmit timestamp value of the CCO based on the receive timestamp value it receives, to confirm whether the CCO transmit timestamp value and the calculated CCO transmit timestamp value are consistent. If they are inconsistent, the STA will adjust the frequency of its local clock, thereby achieving time calibration at the STA.

[0076] The above provides a detailed explanation of the CCO terminal of the concentrator and the STA terminals of multiple first-layer slave nodes. However, in a multi-layer network, clock synchronization is implemented hierarchically. In nodes at levels after the first-layer slave nodes, clock synchronization is achieved by receiving proxy beacons sent by the first-layer slave nodes. They then calculate and calibrate their own clock frequencies according to the aforementioned method, ensuring clock synchronization across the entire multi-layer network.

[0077] In addition to the STA (Stationary Access Point) terminal, the data acquisition unit at the slave node also includes a measurement unit. The measurement unit is connected to the STA terminal and can cooperate with it to perform other tasks. For example, after the data acquisition unit synchronizes its clock with the concentrator, the measurement unit works with the STA terminal to achieve data interaction with the concentrator's CCO (Concentrator Control Center) terminal, undertaking tasks such as waveform data acquisition and result uploading. Furthermore, the measurement unit can acquire corresponding waveform data and perform edge computing on the waveform data. It should be noted that the measurement unit is an Power Measurement Unit (EMU) to achieve low-cost and low-latency reading.

[0078] The functions of the measurement unit will be explained in detail below.

[0079] Here, we will elaborate on how the measurement unit works in conjunction with the STA terminal to achieve data interaction with the CCO terminal of the concentrator, and how it undertakes tasks such as waveform data acquisition and result uploading.

[0080] like Figure 2 As shown, the STA (Stationary Access Point) of the data acquisition unit sends an association request to the CCO (Concentrator Control Center) of the concentrator. The CCO verifies the identity of the STA based on the configured whitelist and replies to the request, confirming the signal to complete the network setup. Subsequently, the STA and CCO perform frequency offset synchronization to calibrate the frequency offset between devices to ensure stable communication. The CCO periodically sends a clock request command to the concentrator. Upon receiving the clock request, the concentrator replies with its clock time to maintain system time synchronization. Then, the CCO initiates a perpetual calendar entry and broadcasts clock synchronization information to all STAs. After receiving the information, the STAs notify the measurement unit via a broadcast time synchronization command to perform clock calibration operations, ensuring that the time of all devices is consistent.

[0081] The CCO terminal initiates a data acquisition entry and sends the acquisition time to all STA terminals. The STA terminals inform the measurement unit of the acquisition time in advance, preparing for acquisition. When the acquisition time arrives, the STA terminal sends a terminal signal to the measurement unit, triggering the measurement unit to immediately start the data acquisition process. Approximately five seconds after the STA terminal sends an IO interrupt notification, it reads the data acquired by the measurement unit. A second pulse is continuously sent to the measurement unit after network access to synchronize the clock drive signal and maintain the long-term stability of the device clock. Finally, the concentrator actively acquires the precise measurement data stored on the STAs according to a preset cycle (e.g., hourly or per entry) to complete data aggregation and analysis.

[0082] As can be seen, in this embodiment, the STA terminal of the concentrator is equivalent to a communication module, which is responsible for communicating with the CCO terminal in the concentrator to receive and maintain network-wide time synchronization. Simultaneously, it supports both carrier and wireless communication, allowing the selection of an appropriate communication method based on the actual application scenario, thereby improving the system's flexibility and adaptability to achieve high-precision clock synchronization across the entire network.

[0083] The STA (Stationary Access Point) of the data acquisition unit and the measurement unit employ phase-locked loop (PLL) or second-pulse synchronization, and utilize interrupt or pulse synchronization for clock acquisition. The PLL ensures that the clock signal at the STA and the clock signal at the measurement unit are consistent in frequency and phase. Second-pulse synchronization uses a signal of one pulse per second to calibrate the clock, ensuring time synchronization. The STA can use an interrupt signal to trigger the clock acquisition operation, while pulse synchronization acquires clock data based on specific pulse signals, guaranteeing accurate clock data synchronized with the system time. Additionally, it stores the acquired data, temporarily saving data collected from the measurement unit and other devices to prevent data loss due to communication failures or other reasons.

[0084] The above describes how the measurement unit works in conjunction with the STA terminal to enable data interaction with the CCO terminal of the concentrator, and to handle waveform data acquisition and result uploading.

[0085] However, in this embodiment, the measurement unit also undertakes edge computing, which will be explained in detail in subsequent steps.

[0086] Next, step S200 is executed to perform time-domain or frequency-domain adjustment on the voltage waveform data and current waveform data to perform phase-shifting processing on the voltage waveform data and current waveform data, and obtain the phase-shifted signal.

[0087] Because the voltage and current waveform data acquired by the measurement unit are obtained by continuous analog-to-digital conversion based on the sampling clock, and these data are distributed across measurement units of different acquisition units, their sampling times are asynchronous. Figure 3 As shown, when the measurement unit responds to the synchronization trigger signal (as indicated by the green dashed line) and begins collecting subsequent data, the first sampling point it acquires (as marked by the orange arrow) cannot be precisely aligned with the starting position of the sampling period after the trigger is initiated. Therefore, to solve the data synchronization deviation problem caused by asynchronous sampling of distributed measurement units, it is necessary to perform real-time phase shifting processing on the signal to better align the signal in time, reduce data synchronization deviation, and facilitate more accurate monitoring, analysis, and control of the power grid.

[0088] In step S200, when performing edge calculations on voltage waveform data and current waveform data, there are two different methods: one is to perform time-domain adjustment, and the other is to perform frequency-domain adjustment.

[0089] The following section will elaborate on how to process voltage and current waveform data using time-domain adjustment.

[0090] The voltage and current waveform data are time-domain adjusted to perform phase-shifting processing and obtain the phase-shifted signal. This includes: constructing a signal model; performing offline coefficient pre-calculation on the voltage and current waveform data in the signal model to generate phase-shifting coefficients; and using an online sliding window to perform convolution operations on the phase-shifting coefficients in real time and perform sliding compensation to obtain the phase-shifted signal.

[0091] First, a signal model needs to be constructed. It should be noted that the steps for constructing a signal model are: setting system variables; configuring signal parameters; and constructing the signal model based on the system variables and signal parameters.

[0092] System variables are the settings of some basic parameters during the construction of a signal model, which affect the characteristics and performance of the signal model. In this embodiment, system variables include elements such as polynomial order, sampling window, and phase shift duration. The polynomial order determines the degree of the highest-degree term in the polynomial; different orders will cause the polynomial to exhibit different curve shapes, thus affecting the degree to which the signal model fits the actual signal. The sampling window refers to the size of the time window selected when discretely sampling a continuous signal. The sampling window determines the time period for acquiring signal data, and its size affects the signal resolution and spectral characteristics. The phase shift duration refers to the length of time for phase shifting of the signal.

[0093] In addition to system variables, the signal itself has some specific parameters that need to be configured. These parameters directly affect the specific characteristics of the signal, such as its amplitude, frequency, and phase. After setting the system variables and configuring the signal parameters, the system variables and signal parameters are integrated to construct a signal model. The signal model can then be used to analyze, predict, and process voltage and current waveform data.

[0094] Subsequently, offline coefficient pre-calculation is performed on the voltage and current waveform data in the signal model, and phase shift coefficients are generated. The specific steps include: constructing the Vandermonde matrix, the expression of which is:

[0095] ;

[0096] Where L is the sampling window length and M is the polynomial order; calculate the normal equation coefficient matrix of the Vandermonde matrix: Set the target phase point and construct the target vector based on the target phase point; calculate the coefficient vector based on the normal equation coefficient matrix and the target vector; generate the phase shift coefficient based on the coefficient vector.

[0097] Specifically, when performing offline coefficient pre-calculation of voltage and current waveform data in the signal model, it is necessary to first construct the Vandermonde matrix and use it as the basis for subsequent calculations to establish a relationship between the discrete data points in the data and the coefficients of the polynomial.

[0098] Calculate the normal equation coefficients of the Vandermonde matrix. The normal equation matrix is ​​the key matrix in least squares fitting. Through specific calculations, it is obtained as a (M+1)*(M+1) dimension matrix, whose function is to find a set of polynomial coefficients that minimizes the sum of squared errors between the fitted curve and the actual data points. This calculation ensures the positive definiteness of the matrix, thus guaranteeing the uniqueness and numerical stability of the least squares fitting solution. In practice, the algorithm efficiently handles large-scale data points, providing a reliable foundation for subsequent calculation of the coefficient vector.

[0099] Then, the target phase point is set, and a phasor target is constructed based on the target relative point. The formula for setting the target phase point is as follows: Where ΔT is a user-defined phase shift. Its physical meaning is that the time offset Toffset is equal to ΔT multiplied by the sampling period Ts. In this embodiment, the signal's position on the time axis can be manually adjusted via ΔT to achieve phase shift.

[0100] In addition, a target phasor needs to be constructed based on the target phase point. The formula for constructing the target phasor is:

[0101] ;

[0102] In this embodiment, the construction process is directly combined with the clock synchronization mechanism. By iteratively optimizing the phase angle, the phase difference between each measurement point in the distribution area is minimized, thereby improving the synchronization accuracy and stability of the low-voltage distribution network.

[0103] Then, the coefficient phasors are calculated based on the normal equation coefficient matrix and the target phasor. The formula for calculating the coefficient phasors is: The solution vector, or coefficient phasor u, is obtained, with a dimension of (M + 1) × 1. It should be noted that the coefficient phasor u contains the coefficients of the polynomials and is the result of least-squares fitting.

[0104] Finally, the phase shift coefficient u is generated based on the phasor coefficient, and then calculated using the formula... Calculate and generate a phase shift coefficient of dimension L×1. This phase shift coefficient can then be used to adjust the phase of voltage and current waveform data to meet specific signal processing requirements.

[0105] After generating the phase-shifting coefficients, an online sliding window is needed to perform convolution operations on the phase-shifting coefficients in real time and perform sliding compensation to phase-shift the voltage waveform data and current waveform data to obtain the phase-shifted signal.

[0106] After generating the phase-shift coefficients, an online sliding window is used to perform convolution operations on the phase-shift coefficients in real time, followed by sliding compensation. This phase-shifts the voltage and current waveform data, resulting in a phase-shifted signal. The specific steps are: acquiring the sampling data window; loading the phase-shift coefficients; performing convolution operations on the phase-shift coefficients; and outputting the phase-shifted signal. It should be noted that these steps must be executed until all data points have been processed before the entire process ends. In this embodiment, a sliding window is used for the convolution operation on the phase-shift coefficients, processing new data as it arrives. Using a sliding window to convolve the phase-shift coefficients allows the characteristics of the phase-shift coefficients to be applied to the original voltage and current waveform data, thereby achieving phase adjustment.

[0107] In this embodiment, the fifth-order least squares fitting algorithm is used as the core phase-shifting algorithm to perform time-domain adjustment on the voltage waveform data and the current waveform data, and to perform phase-shifting processing on the voltage waveform data and the current waveform data to obtain the phase-shifted signal.

[0108] Since the fundamental signal of the power grid is a standard sine wave, the fifth-order least squares fitting algorithm can match the characteristic direction of the standard sine wave well, thus processing the power grid signal more accurately. Furthermore, the fifth-order polynomial function possesses optimal sine approximation characteristics in terms of time-domain waveform, zero-crossing characteristics, and harmonics not exceeding the 15th order. It can more accurately approximate the true waveform of the power grid signal, reducing errors caused by harmonics and other factors.

[0109] Furthermore, the algorithm employs a two-stage architecture to achieve phase-shifted output. First, phase-shifting coefficients are generated through offline coefficient pre-calculation, specifically by solving a system of least squares equations using Gaussian elimination. Then, an online sliding window is used to perform real-time convolution on the phase-shifting coefficients. Even under complex power grid waveform characteristics and a 6.4kHz sampling rate, it achieves a phase-shifting accuracy of less than 1 microsecond, ensuring the accuracy and stability of the phase-shifting process.

[0110] The following section will elaborate on how to process voltage and current waveform data using frequency domain adjustment.

[0111] Frequency domain adjustment is performed on voltage and current waveform data to phase-shift the voltage and current waveform data and obtain the phase-shifted signal. This includes: performing Fourier transform on the voltage and current waveform data to obtain the signal spectrum; modifying the phase component in the signal spectrum, where the formula for modifying the phase component is: output phase = original phase + fixed offset + data synchronous phase shift; extracting phasors based on the phase component, aligning the voltage and current waveform data, and obtaining the phase-shifted signal.

[0112] Specifically, the voltage and current waveform data first need to be subjected to Fourier transform (FFT) to convert the time-domain signal into a frequency-domain signal, thus obtaining the signal spectrum. The spectrum represents the distribution of different frequency components of the signal.

[0113] Next, the phase components in the signal spectrum are modified. These phase components contain the signal's phase information. The formula for modifying the phase components is: Output Phase = Original Phase + Fixed Offset + Data Synchronization Phase Shift. Here, the original phase is the phase value corresponding to each frequency component after Fourier transform. The fixed offset is the factory calibration value. Due to errors during equipment manufacturing, a certain phase deviation may occur during signal processing. This fixed phase offset, obtained through factory calibration, compensates for the phase deviation, eliminating phase deviations caused by equipment manufacturing errors. Data synchronization phase shift refers to the additional phase shifting operation performed on the corresponding signals during signal synchronization to ensure that the phases of different signals remain consistent during synchronization. This step corrects the phase angle by modifying the phase components to improve measurement accuracy.

[0114] Phasor extraction is performed based on phase components. Voltage and current waveform data are aligned to obtain the phase-shifted signal. After correcting the phase components of the spectrum, the required phasors are extracted based on the corrected spectrum information to obtain the phase-shifted signal.

[0115] Frequency domain adjustment of voltage and current waveform data avoids time-domain convolution operations and reduces computational complexity compared to time-domain adjustment.

[0116] After step S200 is executed, step S300 is then executed, where a windowing operation is performed on the phase-shifted signal, and phase compensation is performed to obtain phasor data. Step S300 specifically includes the following steps: applying a window function to the phase-shifted signal to obtain a windowed discrete signal; performing a Fourier transform on the windowed discrete signal to obtain a complex spectrum; performing phase compensation on the complex spectrum based on the group delay characteristic of the window function to obtain a corrected spectrum; and extracting precise phasor values ​​from the corrected spectrum to obtain phasor data.

[0117] First, a window function is applied to the phase-shifted signal. Since the phase-shifted signal is a discrete signal, a windowed discrete signal is obtained to improve the spectral characteristics of the signal.

[0118] Next, a Fourier transform is performed on the windowed discrete signal to convert the signal from the time domain to the frequency domain, obtaining a complex spectrum to reveal the distribution of different frequency components in the signal.

[0119] Then, based on the group delay characteristics of the window function, phase compensation is performed on the Fourier transform result to correct the phase deviation caused by the window function and the processing procedure. For a window function, it introduces different phase delays for different frequency components of the signal. This phase delay is frequency-dependent; this is the delay characteristic of the window function. Different types of window functions have different group delay characteristics. Generally, window functions distort the phase of the signal, leading to inaccurate phase information.

[0120] Therefore, due to the group delay characteristic of the window function, the phase spectrum obtained after windowing the signal and performing a Fourier transform will have a deviation, and this deviation is jointly generated by the window function and the entire processing (such as windowing operation, Fourier transform, etc.). In order to obtain accurate phase information, phase compensation is required for the result after the Fourier transform.

[0121] The specific method of phase compensation is as follows: based on the group delay characteristics of the window function, the phase deviation introduced by each frequency component is calculated. Then, this deviation is subtracted from the complex spectrum after Fourier transform, thereby correcting the phase deviation caused by the window function and the processing procedure, and finally obtaining the corrected spectrum. Phase compensation of the complex spectrum can make the obtained phase information more accurate.

[0122] Finally, precise phasor values ​​are extracted from the corrected spectrum to obtain phasor data.

[0123] Specifically, after obtaining the phase-shifted signal, it is necessary to perform windowing processing on the phase-shifted signal, which is achieved by using a window function.

[0124] In windowing the phase-shifted data, the selection of the window function must adhere to the phase fidelity principle. In this embodiment, two schemes follow this principle. The first is a zero-phase-distortion scheme, which requires that the selected window function, when windowing the phase-shifted signal, must not destroy the original phase information of the signal or introduce additional phase distortion. It must ensure that the phase relationship of the signal remains essentially consistent before and after processing, ensuring that the phase characteristics of the signal can be accurately preserved and utilized in subsequent signal analysis and processing, thereby obtaining more accurate processing results. The second is a linear phase calibration strategy. By pre-measuring the group delay parameter of the window function, the phase is calibrated in subsequent processing through digital compensation to eliminate the phase influence caused by the window function. In this embodiment, the second scheme is preferred.

[0125] Finally, step S400 is executed to upload the phasor data to the concentrator. Steps S100-S300 are all performed by the measurement unit in the data acquisition unit. However, this measurement unit connects to the concentrator's CCO terminal via the STA terminal for data exchange. Therefore, after the measurement unit acquires the phasor data, it uploads the phasor data to the concentrator via the STA terminal, facilitating subsequent analysis and processing by the concentrator.

[0126] The embodiment is merely a specific example and does not indicate that this is the only way to implement the present invention.

[0127] Example 2:

[0128] A low-voltage phasor measurement system based on field clock synchronization is provided for performing the low-voltage phasor measurement method based on field clock synchronization described in Example 1, such as... Figure 4 As shown, the system includes a concentrator located at the master node and data collectors located at multiple slave nodes. The data collectors synchronize time and exchange data with the concentrator. The concentrator includes a CCO terminal, and the data collectors include STA terminals. The data collectors are connected to the concentrator through the STA and CCO terminals. The concentrator and data collectors share a network reference time through a local communication network, enabling network-wide time synchronization. The data collectors also include a measurement unit connected to the STA terminal, which exchanges data with the concentrator's CCO terminal. The measurement unit is also used for edge computing of voltage and current waveform data.

[0129] Specifically, the system comprises two parts: a concentrator and collectors. The concentrator is located at the master node, and the collectors are correspondingly located at the slave nodes. The concentrator includes a CCO (Concurrent Control Officer) terminal, which is responsible for coordinating and managing the entire network. The collectors include STA (Standard Access Point) terminals, which connect to the concentrator's CCO terminal for time synchronization. In this embodiment, the concentrator and collectors share a common network reference time through the local communication network, thereby achieving network-wide time synchronization. This ensures that the collectors and concentrators are in sync, facilitating accurate data collection and processing and avoiding data corruption caused by time differences. The time synchronization process between the collectors and the concentrator is described in Embodiment 1 and will not be elaborated upon in this embodiment.

[0130] The data acquisition unit also includes a measurement unit connected to the STA terminal, which interacts with the concentrator via the STA terminal. Furthermore, the measurement unit possesses edge computing capabilities, enabling it to directly perform edge computing on the acquired voltage and current waveform data. This allows for direct data processing and analysis of the voltage and current waveform data, reducing data transmission volume, lowering network latency, and improving system response speed and processing efficiency.

[0131] Overall, the system described in this embodiment achieves functions such as time synchronization, data interaction, and edge computing of voltage and current waveform data through the collaborative work of a concentrator and multiple data acquisition units. It can be deployed on a large scale in low-voltage distribution areas, is highly economical, and solves the dual challenges of hardware cost and synchronization accuracy.

[0132] Example 3:

[0133] Based on the same inventive concept, the present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of any of the methods of the low-voltage phasor measurement method based on field clock synchronization described in Embodiment 1 above.

[0134] The above description is merely a preferred embodiment of the present invention. Those skilled in the art will understand that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A low-voltage phasor measurement method based on field clock synchronization, characterized in that, include: The voltage waveform data and current waveform data of the slave nodes on the power line are acquired. There are multiple slave nodes. The voltage waveform data and the current waveform data are acquired by the corresponding data acquisition devices set at the slave nodes. The data acquisition devices at the multiple slave nodes are synchronized with the concentrator at the master node in time and interact with the data. The voltage waveform data and the current waveform data are adjusted in the time domain or frequency domain to perform phase shifting processing on the voltage waveform data and the current waveform data, and the phase-shifted signal is obtained. The phase-shifted signal is windowed and phase compensation is performed to obtain phasor data; The phasor data is uploaded to the concentrator.

2. The low-voltage phasor measurement method based on field clock synchronization according to claim 1, characterized in that, The voltage waveform data and the current waveform data are time-domain adjusted to perform phase-shifting processing on the voltage waveform data and the current waveform data, and a phase-shifted signal is obtained, including: Construct a signal model; In the signal model, offline coefficient pre-calculation is performed on the voltage waveform data and the current waveform data to generate phase shift coefficients; The phase-shifting coefficients are convolved in real time using an online sliding window, and sliding compensation is performed to obtain the phase-shifted signal.

3. The low-voltage phasor measurement method based on field clock synchronization according to claim 2, characterized in that, The step of performing offline coefficient pre-calculation on the voltage waveform data and the current waveform data in the signal model to generate phase shift coefficients includes: Construct the Vandermonde matrix, the expression of which is: ； Where L is the sampling window length and M is the polynomial order; Calculate the normal equation coefficient matrix of the Vandermonde matrix: ; Set a target phase point and construct a target vector based on the target phase point; Calculate the coefficient vector based on the normal equation coefficient matrix and the target vector; The phase shift coefficients are generated based on the coefficient vector.

4. The low-voltage phasor measurement method based on field clock synchronization according to claim 2, characterized in that, The construction of the signal model includes: Set system variables; Configure signal parameters; Construct a signal model based on the system variables and the signal parameters.

5. The low-voltage phasor measurement method based on field clock synchronization according to claim 1, characterized in that, Frequency domain adjustment is performed on the voltage waveform data and the current waveform data to perform phase shifting processing on the voltage waveform data and the current waveform data, and to obtain the phase-shifted signal, including: Perform Fourier transform on the voltage waveform data and the current waveform data to obtain the signal spectrum; Modify the phase component in the signal spectrum, wherein the formula for modifying the phase component is: Output phase = Original phase + Fixed offset + Data synchronization phase shift; Based on the phase components, phasors are extracted, the voltage waveform data and the current waveform data are aligned, and the phase-shifted signal is obtained.

6. The low-voltage phasor measurement method based on field clock synchronization according to claim 1, characterized in that, The step of windowing the phase-shifted signal and performing phase compensation to obtain phasor data includes: A window function is applied to the phase-shifted signal to obtain a windowed discrete signal; Perform a Fourier transform on the windowed discrete signal to obtain the complex spectrum; Phase compensation is performed on the complex spectrum based on the group delay characteristics of the window function to obtain the corrected spectrum; Precise phasor values ​​are extracted from the corrected spectrum to obtain phasor data.

7. A low-voltage phasor measurement system based on field clock synchronization, characterized in that, The system is used to perform the low-voltage phasor measurement method based on field clock synchronization according to any one of claims 1-6. The system includes a concentrator located at a master node and acquisition units located at multiple slave nodes. The acquisition units synchronize time and interact with the concentrator.

8. The low-voltage phasor measurement system based on field clock synchronization according to claim 7, characterized in that, The concentrator includes a CCO terminal, and the collector includes a STA terminal. The collector is connected to the concentrator through the STA terminal and the CCO terminal. The concentrator and the collector share a network reference time through the local communication network, enabling the concentrator and the collector to synchronize their time across the entire network.

9. The low-voltage phasor measurement system based on field clock synchronization according to claim 8, characterized in that, The data acquisition unit also includes a measurement unit connected to the STA terminal. The measurement unit interacts with the CCO terminal of the concentrator through the STA terminal. The measurement unit is also used to perform edge computing on the voltage waveform data and current waveform data.

10. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which, when executed, implements the low-voltage phasor measurement method based on field clock synchronization as described in any one of claims 1-6.

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