Real-time data transmission method for load identification and fault diagnosis

Abstract

The invention discloses a real-time data transmission method for load identification and fault diagnosis. The method comprises a data preprocessing unit and a data processing unit. The data preprocessing unit comprises the steps that after voltage and current data are collected, a phase-locked loop is used for extracting a voltage phase, and voltage and current signals are segmented and identified according to the phase; and performing frequency domain conversion on the identified current signal. The data processing unit is used for extracting time domain and frequency domain characteristic values, and distinguishing transient state and steady state data according to the characteristic values; and the transient and steady state data volumes are controlled according to actual requirements so as to reduce the data volume. According to the method, the bandwidth required by data transmission and the storage space required by data storage can be greatly reduced.

Description

Technical Field

[0001] The present application relates to the field of data transmission, and in particular to the field of real-time data remote transmission for load identification and fault diagnosis. Background Art

[0002] The load identification and fault diagnosis system architecture is generally composed of a collection device, a load identification and fault diagnosis server, and a client. The collection device is responsible for collecting analog quantities and sending them to the server. Generally speaking, the collection device is used for the collection and transmission of analog quantities. It is necessary to send one cycle (voltage frequency 50Hz) of data to the server every 20 milliseconds, or send one frame of data to the server at regular intervals. The server monitors and parses the data to identify the load and diagnose faults. Assuming the sampling rate is 12.8kHz, 256 points of voltage data and 256 points of current data are sent every 20 milliseconds. If each point occupies two bytes, that is, 16 bits represent an analog quantity, 30 days a month (data traffic=256*2*2*8*50*60*60*24*30) is about 123GB of traffic, which is high in traffic costs and heavy in server burden. Therefore, a traffic control is needed to reduce the amount of data and reduce traffic costs. Summary of the invention

[0003] The purpose of the present application is to provide a data transmission method to solve the problem of large data transmission flow in the prior art.

[0004] The embodiment of the present application provides a data transmission method for load identification and fault diagnosis, the method comprising: sampling, voltage phase-locked loop, time domain and frequency domain conversion, eigenvalue extraction, transient and steady state judgment, data caching and transmission.

[0005] In some embodiments, the method divides the discrete voltage and current signals into units of a fundamental wave cycle, and the dividing point is when the voltage phase is 0. This ensures that the starting point of each frame of current data is the voltage zero crossing point, and the server can calculate the power factor of the load based only on the current signal. The calculation method can be Fourier extraction of the phase φ of the current fundamental wave, and cosφ is the load power factor. Therefore, in load identification and fault diagnosis applications based on current signals, voltage data may not be transmitted.

[0006] In some embodiments, in the segmentation method, the segmentation point may also be a voltage zero crossing point.

[0007] In some embodiments, the segmented voltage and current signals are subjected to time domain eigenvalue calculation to calculate the active power, reactive power, current root mean square value and maximum value of a fundamental wave cycle.

[0008] In some embodiments, the characteristic value calculation also includes performing a frequency domain transform on the current signal using a Fourier algorithm to extract the frequency domain characteristics of the current signal, including the fundamental component and the 2nd to 13th harmonic components.

[0009] In some embodiments, the transient state and the steady state are determined according to the rate of change of the characteristic values ​​of the previous fundamental wave cycle and the current fundamental wave cycle.

[0010] In some embodiments, if the current cycle is determined to be transient, the active power and current waveform of the cycle are transmitted. In the case of transmitting only current data, the server cannot accurately calculate the active power of the load. Therefore, the collection device needs to upload the active power. The server obtains high-precision active power data and draws an accurate power curve.

[0011] In some embodiments, if the current cycle is judged to be steady state, only the active power of the current cycle is transmitted. In the steady state, it is considered that the data of the current cycle is almost the same as the data of the previous cycle, and the acquisition device only uploads the active power. The server obtains high-precision active power data and draws an accurate power curve. For some users, there are fewer transient periods in a day, such as starting up a computer, charging a mobile phone, switching lighting systems, etc. Therefore, the transmission data will drop significantly. Assuming the sampling rate is 12.8kHz, the transient time is 1%, and 1% of the time is 256 points of current data. If each point occupies two bytes, that is, 16 bits represent an analog quantity, 30 days a month (data traffic=256*2*8*50*60*60*24*30*1%) is about 0.62 GB of traffic.

[0012] In some embodiments, each frame of data transmits x fundamental wave period data, that is, data is sent once every 0.02*x seconds. The value of x is based on network bandwidth and server efficiency. For example, each frame of data transmits 10 fundamental wave period data, and data is sent once every 0.2 seconds.

[0013] In some embodiments, in the data transmission method, each frame of data can transmit multiple fundamental wave period data, depending on other requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments:

[0015] Figure 1 This is an architecture diagram of a load-identified real-time data remote transmission system provided by an embodiment of the present invention;

[0016] Figure 2 The present invention is a flowchart of a real-time data remote transmission with load identification provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0017] This section will describe in detail the specific embodiments of the present invention. The purpose of the drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0018] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0019] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0020] In view of the shortcoming of large amount of data in existing load identification and fault diagnosis, the present invention proposes a data transmission method to solve the problem of large amount of transmission data flow in the prior art.

[0021] The system architecture of the present invention will be described in detail below. Figure 1 As shown, data processing includes two units: data preprocessing unit and data processing unit. The data preprocessing unit includes: data acquisition, voltage phase locking and current frequency domain conversion. The data processing unit includes: feature value extraction, transient and steady state detection, waveform data cache management, and finally transmits the data to the server.

[0022] The data transmission process of the present invention will be described in detail below. Figure 2 As shown, definition: Arrays u 1[Num] is the voltage data of the current fundamental cycle. Arrays i 1[Num] is the current fundamental cycle current data, Arrays u 0[Num] is the voltage data of the previous fundamental cycle. Arrays i 0[Num] is the current data of the previous fundamental cycle. Arrays i 10 [Num] is i 1[Num] and i 0[Num] difference, Num is the number of sampling points in a fundamental period. If the sampling frequency is 12.8kHz, then Num is 256. 10 Yes | i 10 [Num]|The maximum value, R 10 yes i 10 The root mean square value of [Num], i 10_3 ,i 10_5 ,i 10_7 ,i 10_9 ,iT 10_11 , i 10_13 They are i 10 The 3rd, 5th, 7th, 9th, 11th, and 13th harmonic values ​​of [Num]; Cnt is a counter. When the voltage phase is 0, cnt is cleared, indicating that a fundamental wave cycle array cache is completed. After the cache is completed, the feature value is extracted.

[0023] Specifically, the extracted eigenvalues ​​include time domain eigenvalues: active power P1, P0, reactive power Q1, Q0, current effective value R 10 , maximum value M 10 ; and frequency domain eigenvalues: 2nd to 13th harmonic values ​​i 10_3 , i 10_5 , i 10_7 , i 10_9 , i 10_11 , i 10_13 .

[0024] Specifically, in some embodiments of the present invention, the voltage phase-locked loop is an existing publicly available technical algorithm, such as a phase-locked loop based on a synchronous rotating coordinate system. It can also be simply considered that the voltage zero-crossing point is the voltage phase being 0.

[0025] Specifically, in some embodiments of the present invention, the method for solving the maximum value, the root mean square value, and the harmonic value is an existing publicly available technical algorithm, such as the bubble method for solving the maximum value and the Fourier algorithm for solving the harmonic value.

[0026] The temporary steady state judgment conditions are as follows: 1. M 10 >M N , M N is the set threshold; 2. R 10 >R N , R N is the set threshold; 3. i10_3 > i N_3 , i 10_5 > i N_5 , i 10_7 > i N_7 , i 10_9 > i N_9 , i 10_11 > i N_11 , i 10_13 > i N_13 ,i N_3 ,i N_5 ,i N_7 ,i N_9 ,i N_11 ,i N_13 is the set threshold; 4. (P1-P0) / P1>x%, P1 is the active power of the current fundamental cycle, P0 is the active power of the previous fundamental cycle, and x% is the set threshold; 5. (Q1-Q0) / Q1>y%, Q1 is the reactive power of the current fundamental cycle, Q0 is the reactive power of the previous fundamental cycle, and y% is the set threshold.

[0027] That is, the transient state and steady state are distinguished from the maximum value, RMS value, 3rd, 5th, 7th, 9th, 11th, 13th harmonic value and power change rate of the two cycle data changes. N , R N ,i N_3 ,i N_5 ,i N_7 ,i N_9 ,i N_11 ,i N_13 ,x%,y% can be set according to the actual situation. If one of the four conditions is met, it is a transient state.

[0028] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A real-time data transmission method for load identification and fault diagnosis, applied in the field of load identification and fault diagnosis, characterized in that: By sampling the voltage and current locally, the sampled values ​​are divided into units of a fundamental wave cycle, and characteristic values ​​are extracted from the current fundamental wave cycle and the previous fundamental wave cycle data, and the temporary and steady states are judged according to the characteristic values. The content of the uploaded data is determined according to the temporary and steady states, reducing the data transmission traffic.

2. The method according to claim 1, characterized in that The split point is when the voltage phase is 0.

3. The method according to claim 1, characterized in that The amount of data transmitted is not fixed but varies according to the load conditions.

4. The method according to claim 1, characterized in that: The eigenvalue is calculated once per fundamental period.

5. The method according to claim 4, characterized in that The characteristic values ​​include time domain and frequency domain characteristic values: active power, reactive power, current effective value, maximum value, and 2nd to 13th harmonic values.

6. The method according to claim 5, characterized in that Extract characteristic values ​​based on the current fundamental wave period and the previous fundamental wave period data to determine whether it is temporary or steady state.

7. The method according to claim 6, characterized in that For a transient period, the active power and current waveform of the period are transmitted.

8. The method according to claim 6, characterized in that For a steady-state period, the active power of that period is transferred.

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