A voltage adaptive sampling method for high-voltage switchgear

Abstract

The present invention discloses a voltage adaptive sampling method for a high-voltage switchgear. In order to overcome the problems in the prior art that the current and voltage acquisition frequencies are fixed, which easily causes waste of resources or misses important features, the present invention includes the following steps: S1: Calculate the rated withstand voltage value according to the altitude position of the high-voltage switchgear and the collected temperature data; S2: Determine the sampling frequency level according to the set maximum sampling frequency and minimum sampling frequency; S3: Fit the currently collected voltage into a voltage curve, match the voltage change curve in the historical database, predict the voltage value in the next time period, and calculate the corresponding voltage sampling frequency. By predicting the voltage value in the next stage through historical data, and thus calculating the corresponding voltage sampling frequency, it can not only ensure that all characteristic values are collected, but also avoid waste of resources.

Description

Technical Field

[0001] The present invention relates to the field of voltage and current acquisition, and particularly to a voltage adaptive sampling method for high-voltage switch cabinets. Background Art

[0002] Switch cabinets designed for power monitoring in power systems, industrial and mining enterprises, public facilities, intelligent buildings, etc. are generally used on the incoming line side of 0.4 kV voltage. Specifically, they can be used in conjunction with low-voltage power-saving cabinets or incoming line cabinets, and can measure common electrical parameters in a three-phase power grid, such as three-phase voltage, current, active power, reactive power, apparent power, power factor, power grid frequency, and four-quadrant electric energy metering. They can monitor one path or multiple paths simultaneously. In the prior art, various data are displayed through meters, and the meters are directly installed on the meter door of the power distribution cabinet. The current sampling signal directly comes from the secondary side of the current transformer installed in the main circuit, and the voltage sampling signal directly comes from the main circuit.

[0003] However, usually the current and voltage sampling frequencies are fixed. If the sampling frequency is too low, it is easy to miss important characteristic values; if the sampling frequency is high, a large number of repeated and useless values will appear, resulting in waste of resources.

[0004] For example, a "switch cabinet fault current acquisition device" disclosed in a Chinese patent document, with the publication number CN102288854A, includes: a fault current acquisition and conditioning circuit; a normal and steady-state current acquisition and conditioning circuit; a high-speed sampling circuit connected to the fault current acquisition and conditioning circuit; a fault current threshold dynamic setting and fault current acquisition start judgment module connected to the normal and steady-state current acquisition and conditioning circuit; a single-chip microcomputer connected between the normal and steady-state current acquisition and conditioning circuit and the fault current threshold dynamic setting and fault current acquisition start judgment module; and a connection between the high-speed sampling circuit and the single-chip microcomputer, and a bus and its control module connected to the single-chip microcomputer. This solution has a fixed sampling frequency. If the sampling frequency is too low, it is easy to miss important characteristic values; if the sampling frequency is high, a large number of repeated and useless values will appear, resulting in waste of resources. Summary of the Invention

[0005] The present invention mainly solves the problem that the current and voltage sampling frequencies in the prior art are fixed, which easily causes waste of resources or misses important characteristics; and provides a voltage adaptive sampling method for high-voltage switch cabinets.

[0006] The above technical problems of the present invention are mainly solved by the following technical solutions:

[0007] A voltage adaptive sampling method for high-voltage switch cabinets includes the following steps:

[0008] S1: Calculate the rated withstand voltage value according to the altitude position of the high-voltage switch cabinet and the collected temperature data;

[0009] S2: Determine the sampling frequency level according to the set maximum sampling frequency f max and the minimum sampling frequency f min ;

[0010] S3: Fit the currently collected voltage into a voltage curve, match the voltage change curve in the historical database, predict the voltage value in the next time period, and calculate the corresponding voltage sampling frequency.

[0011] This solution changes the sampling frequency specifically according to the altitude position and ambient temperature of the actual high-voltage switchgear, with diversity and pertinence. By predicting the voltage value in the next stage through historical data, and then calculating the corresponding voltage sampling frequency, it can not only ensure that all characteristic values are collected, but also avoid waste of resources.

[0012] Preferably, the calculation method of the rated withstand voltage value is:

[0013] V′ R = V R ·K t ·K a

[0014] wherein, V′ R is the actual rated withstand voltage value;

[0015] V R is the standard withstand voltage value of the high-voltage switchgear;

[0016] K t is the temperature correction factor;

[0017] K a is the altitude correction factor.

[0018] Calculating the rated withstand voltage value according to the altitude position of the high-voltage switchgear and the collected temperature data makes the calculation result closer to the usage scenario of the high-voltage switchgear, with pertinence.

[0019] Preferably, the calculation method of the temperature coefficient is:

[0020] K t = 1 + 0.0033(T - 40)

[0021] wherein, T is the ambient air temperature;

[0022] The calculation method of the altitude coefficient is:

[0023]

[0024] wherein, H is the altitude of the installation location of the high-voltage switchgear.

[0025] For the external insulation of equipment used at altitudes above 1000 m but not exceeding 4000 m and the insulation of dry-type transformers, for every 100 m increase in altitude, the insulation strength is reduced by approximately 1%. When testing at locations with an altitude not exceeding 1000 m, the test voltage is multiplied by the altitude correction factor K according to the rated withstand voltage specified in the standard. a

[0026] Preferably, the maximum sampling frequency f max and the minimum sampling frequency f min are evenly divided into X sampling frequency levels, and the sampling frequencies corresponding to each sampling frequency level are:

[0027]

[0028] where f i is the sampling frequency corresponding to the i-th sampling frequency level.

[0029] Dividing the sampling frequency into several different levels and corresponding according to the predicted voltage value can not only ensure that all characteristic values are collected, but also avoid waste of resources.

[0030] Preferably, the step S3 includes the following steps:

[0031] S301: Taking one day as a unit, evenly dividing one day into several time periods;

[0032] S302: Collecting the voltage data of the high-voltage switchgear at the initial frequency or the voltage acquisition frequency of the previous time period, and fitting it into a voltage curve;

[0033] S303: According to the fitted curve, traversing the voltage change curves within one month before and after the same day of previous years in the historical database to find the voltage change curve that is closest in the same time period;

[0034] S304: If there is a closest voltage change curve, predicting the voltage value of the next time period according to this voltage change curve; if there is no closest voltage change curve, using the voltage change curve of the same day of the previous year as the closest voltage change curve and predicting the voltage waveform of the next time period according to this voltage change curve;

[0035] S305: Calculating the corresponding voltage sampling frequency according to the predicted voltage waveform of the next time period.

[0036] Determining the closest curve according to the historical database to predict the voltage change situation of the next time period, thereby calculating the voltage sampling frequency. The selected historical time limit makes the data closer to the situation of the current day, the prediction is more accurate, and at the same time, the selected time is reduced, improving the selection efficiency.

[0037] Preferably, the voltage sampling frequency calculation process is as follows:

[0038] Determine the comparison threshold ΔV according to the rated withstand voltage value and the sampling frequency level;

[0039]

[0040] Among them, V' R is the actual rated withstand voltage value;

[0041] X is the sampling frequency level;

[0042] Decompose the voltage waveform in the next time period into several fluctuation stages; use the points with a slope of 0 on the voltage waveform and the two end points of this time period as boundary points, and each interval between adjacent boundary points is a fluctuation stage;

[0043] Take the median V M of the voltage in a fluctuation stage, and determine whether all voltage values in this fluctuation stage are within the range; if so, the voltage sampling frequency of this fluctuation stage is f min ; otherwise, perform the sampling frequency calculation for this fluctuation stage;

[0044] The sampling frequency calculation process for the fluctuation stage is as follows:

[0045] Determine the sampling frequency level of this fluctuation stage according to the maximum voltage and the minimum voltage of the fluctuation stage;

[0046]

[0047] Among them, i is the i-th sampling frequency level;

[0048] V nmax is the maximum voltage of the n-th fluctuation stage;

[0049] V nmin is the minimum voltage of the n-th fluctuation stage;

[0050] is the ceiling operation;

[0051] f np = f i

[0052] Among them, f np is the sampling frequency of the n-th fluctuation stage;

[0053] f i is the sampling frequency corresponding to the i-th sampling frequency level;

[0054] Determine the voltage sampling frequency of this time period:

[0055] f k = max{f 1p , f 2p , ..., f np}

[0056] where f k is the voltage sampling frequency in the k-th time period.

[0057] Determine the voltage sampling frequency of this time period according to the sampling frequencies of different fluctuation stages.

[0058] Preferably, judge whether the voltage difference between adjacent boundary points is greater than the decomposition threshold; if so, retain it; otherwise, cancel the subsequent boundary point. Avoid interference from small voltage fluctuation data.

[0059] Preferably, judge the sampling frequency level difference corresponding to each fluctuation stage within the same time period; if the difference between the maximum value and the minimum value of the sampling frequency levels corresponding to each fluctuation stage within the same time period is greater than or equal to 3, then use the corresponding sampling frequency f np of each fluctuation stage as the final sampling frequency for adaptive adjustment; if the difference between the maximum value and the minimum value of the sampling frequency levels corresponding to each fluctuation stage within the same time period is less than 3, then use the calculated voltage sampling frequency f k as the final sampling frequency for adaptive adjustment. Avoid the situation where the required sampling frequencies for each fluctuation stage within the same time period vary greatly, and the calculated voltage sampling frequency cannot be fully applicable to all stages.

[0060] The beneficial effects of the present invention are:

[0061] 1. Predict the voltage value in the next stage through historical data, and thus calculate the corresponding voltage sampling frequency, which can not only ensure that all characteristic values are collected, but also avoid waste of resources.

[0062] 2. Change the sampling frequency specifically according to the altitude position and ambient temperature of the actual high-voltage switchgear, which has diversity and specificity.

[0063] 3. Determine the closest curve according to the historical database, and thus predict the voltage change situation in the next time period, and then calculate the voltage sampling frequency. Limiting the selected historical time makes the data closer to the situation of the current day, the prediction is more accurate, and at the same time, the selected time is reduced and the selection efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 is the flowchart of the voltage adaptive sampling method for the high-voltage switchgear of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0065] The technical solution of the present invention will be further specifically described below through embodiments in conjunction with the accompanying drawings.

[0066] Embodiment:

[0067] A voltage adaptive sampling method for a high-voltage switchgear in this embodiment is as Figure 1 shown and includes the following steps:

[0068] S1: Calculate the rated withstand voltage value according to the altitude position of the high-voltage switchgear and the collected temperature data.

[0069] The calculation method of the rated withstand voltage value is:

[0070] V′ R =V R ·K t ·K a

[0071] Wherein, V′ R is the actual rated withstand voltage value;

[0072] V R is the standard withstand voltage value of the high-voltage switchgear;

[0073] K t is the temperature correction factor;

[0074] K a is the altitude correction factor.

[0075] The calculation method of the temperature coefficient is:

[0076] K t =1 + 0.0033(T - 40)

[0077] Wherein, T is the ambient air temperature;

[0078] The calculation method of the altitude coefficient is:

[0079]

[0080] Wherein, H is the altitude of the installation location of the high-voltage switchgear.

[0081] S2: Determine the sampling frequency level according to the set maximum sampling frequency f max and the minimum sampling frequency f min Divide the range between the maximum sampling frequency f

[0082] and the minimum sampling frequency f max and the minimum sampling frequency f min evenly into X sampling frequency levels, and the sampling frequencies corresponding to each sampling frequency level are:

[0083]

[0084] where f i is the sampling frequency corresponding to the i-th sampling frequency level. In this embodiment, X is 5.

[0085] S3: Fit the currently collected voltage into a voltage curve, match the voltage change curve in the historical database, predict the voltage value in the next time period, and calculate the corresponding voltage sampling frequency.

[0086] S301: Divide a day evenly into several time periods in units of one day.

[0087] S302: Collect the voltage data of the high-voltage switchgear at the initial frequency or the voltage acquisition frequency of the previous time period, and fit it into a voltage curve.

[0088] S303: According to the fitted curve, traverse the voltage change curves within one month before and after the same day of each year in the historical database, and find the voltage change curve that is closest in the same time period.

[0089] S304: If there is a closest voltage change curve, predict the voltage value in the next time period according to this voltage change curve;

[0090] If there is no closest voltage change curve, use the voltage change curve on the same day of the previous year as the closest voltage change curve, and predict the voltage waveform in the next time period according to this voltage change curve.

[0091] S305: Calculate the corresponding voltage sampling frequency according to the predicted voltage waveform in the next time period.

[0092] The process of calculating the voltage sampling frequency is as follows:

[0093] Determine the comparison threshold ΔV according to the rated withstand voltage value and the sampling frequency level;

[0094]

[0095] where V′ R is the actual rated withstand voltage value;

[0096] X is the sampling frequency level.

[0097] Decompose the voltage waveform in the next time period into several fluctuation stages; use the points with a slope of 0 on the voltage waveform and the two end points of this time period as boundary points, and each section between adjacent boundary points is a fluctuation stage.

[0098] Judge whether the voltage difference between adjacent boundary points is greater than the decomposition threshold; if so, keep it; otherwise, cancel the subsequent boundary point.

[0099] Take the median value V of the voltage in a fluctuation stageM , determine whether all voltage values in this fluctuation stage are within the range; if so, the voltage sampling frequency of this fluctuation stage is f min ; otherwise, calculate the sampling frequency of this fluctuation stage.

[0100] The process of calculating the sampling frequency of the fluctuation stage is as follows:

[0101] Determine the sampling frequency level of this fluctuation stage according to the maximum voltage and the minimum voltage of the fluctuation stage;

[0102]

[0103] where i is the i-th sampling frequency level;

[0104] V nmax is the maximum voltage of the n-th fluctuation stage;

[0105] V nmin is the minimum voltage of the n-th fluctuation stage;

[0106] is the ceiling operation.

[0107] f np = f i

[0108] where f np is the sampling frequency of the n-th fluctuation stage;

[0109] f i is the sampling frequency corresponding to the i-th sampling frequency level.

[0110] Determine the voltage sampling frequency of this time period:

[0111] f k = max{f 1p , f 2p ,..., f np}

[0112] where f k is the voltage sampling frequency of the k-th time period.

[0113] Judge the difference in sampling frequency levels corresponding to each fluctuation stage within the same time period.

[0114] If the difference between the maximum value and the minimum value of the sampling frequency levels corresponding to each fluctuation stage within the same time period is greater than or equal to 3, then use the corresponding sampling frequency f np of each fluctuation stage as the final sampling frequency for adaptive adjustment;

[0115] If the difference between the maximum and minimum values of the sampling frequency levels corresponding to each fluctuation stage within the same time period is less than 3, then the calculated voltage sampling frequency f k is adaptively adjusted as the final sampling frequency.

[0116] This solution predicts the voltage value in the next stage through historical data, thereby calculating the corresponding voltage sampling frequency, which can not only ensure that all characteristic values are collected, but also avoid waste of resources.

[0117] It should be understood that the embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A voltage adaptive sampling method for a high-voltage switchgear, characterized in that, It includes the following steps: S1: Calculate the rated withstand voltage according to the altitude of the high-voltage switchgear and the collected temperature data; S2: Determine the sampling frequency level according to the set maximum sampling frequency f max and the minimum sampling frequency f min ; S3: Fit the currently collected voltage into a voltage curve, match the voltage change curve in the historical database, predict the voltage value in the next time period, and calculate the corresponding voltage sampling frequency; When testing at a location with an altitude not higher than 1000m, the test voltage is the product of the standard withstand voltage value and the altitude coefficient.

2. The voltage adaptive sampling method for a high-voltage switchgear according to claim 1, characterized in that, The calculation method of the rated withstand voltage is as follows: V′ R = V R ·K t ·K a Among them, V' R is the actual rated withstand voltage value; V R is the standard withstand voltage value of the high-voltage switchgear cabinet; K t is the temperature coefficient; K a is the altitude coefficient.

3. The voltage adaptive sampling method for a high-voltage switchgear according to claim 2, characterized in that, The calculation method of the temperature coefficient is as follows: K t = 1 + 0.0033(T - 40) Where T is the ambient air temperature; The calculation method of the altitude coefficient is as follows: Where H is the altitude of the installation location of the high-voltage switchgear.

4. The voltage adaptive sampling method for a high-voltage switchgear according to claim 1 or 2 or 3, characterized in that, Divide the maximum sampling frequency f max and the minimum sampling frequency f min evenly into X sampling frequency levels, and the sampling frequencies corresponding to each sampling frequency level are: where, f i is the sampling frequency corresponding to the i-th sampling frequency level.

5. The voltage adaptive sampling method for a high-voltage switchgear according to claim 4, characterized in that, The step S3 includes the following steps: S301: Divide a day evenly into several time periods in units of a day; S302: Collect the voltage data of the high-voltage switchgear at the initial frequency or the voltage sampling frequency of the previous time period, and fit it into a voltage curve; S303: According to the fitted curve, traverse the voltage change curves within one month before and after the same day of each year in the historical database, and find the voltage change curve that is closest in the same time period; S304: If there is a closest voltage change curve, predict the voltage value in the next time period according to this voltage change curve; If there is no closest voltage change curve, use the voltage change curve on the same day of the previous year as the closest voltage change curve, and predict the voltage waveform in the next time period according to this voltage change curve; S305: Calculate the corresponding voltage sampling frequency according to the predicted voltage waveform in the next time period.

6. The voltage adaptive sampling method for a high-voltage switchgear according to claim 5, characterized in that, The voltage sampling frequency calculation process is as follows: Determine the comparison threshold ΔV according to the rated withstand voltage and the sampling frequency level; where V′ R is the actual rated withstand voltage value; X is the sampling frequency level; Decompose the voltage waveform in the next time period into several fluctuation stages; use the points with a slope of 0 on the voltage waveform and the two end points of this time period as boundary points, and there is a fluctuation stage between adjacent boundary points; Take the median value V of the voltage in a fluctuation stage M , and determine whether all voltage values in this fluctuation stage are within ; if so, the voltage sampling frequency of this fluctuation stage is f min ; otherwise, calculate the sampling frequency of this fluctuation stage; The sampling frequency calculation process of the fluctuation stage is as follows: Determine the sampling frequency level of this fluctuation stage according to the maximum voltage and the minimum voltage of the fluctuation stage; Where i is the i-th sampling frequency level; V nmax is the maximum voltage value at the nth fluctuation stage; V nmin is the minimum voltage value of the n-th fluctuation stage; is the ceiling operation; f np = f i where f np is the sampling frequency of the n-th fluctuation stage; f i is the sampling frequency corresponding to the i-th sampling frequency level; Determine the voltage sampling frequency of this time period: f k = max{f 1p , f 2p ,..., f np} where f k is the voltage sampling frequency in the k-th time period.

7. A voltage adaptive sampling method for a high-voltage switchgear according to claim 6, wherein, Judge whether the voltage difference between adjacent boundary points is greater than the decomposition threshold; if so, keep it; otherwise, cancel the subsequent boundary point.

8. A voltage adaptive sampling method for a high-voltage switchgear according to claim 6, wherein, Judge the sampling frequency level difference corresponding to each fluctuation stage within the same time period; if the difference between the maximum value and the minimum value of the sampling frequency levels corresponding to each fluctuation stage within the same time period is greater than or equal to 3, then use the corresponding sampling frequency f of each fluctuation stage np as the final sampling frequency for adaptive adjustment; if the difference between the maximum value and the minimum value of the sampling frequency levels corresponding to each fluctuation stage within the same time period is less than 3, then use the calculated voltage sampling frequency f k as the final sampling frequency for adaptive adjustment.

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