A method, medium and system for estimating power loss due to voltage sag

Abstract

The present invention discloses a method, medium and system for estimating the amount of electricity lost due to voltage sag, the method comprising: establishing a daily reference power curve function for each category according to the measured daily historical active power value of the user and the classification of the daily historical active power value; judging whether a voltage sag event occurs according to voltage recording data; if the voltage sag event occurs, judging whether the voltage sag event causes the user to lose electricity; if the voltage sag event causes the user to lose electricity, establishing a sag power curve function according to the active power value of the time period of the voltage sag event; calculating the amount of electricity lost due to voltage sag in the voltage sag event according to the sag power curve function and the daily reference power curve function of a category corresponding to the voltage sag event. The present invention can more accurately estimate the amount of electricity lost by sensitive users in a single voltage sag event for maintenance.

Description

Technical Field

[0001] The present invention relates to the technical field of voltage sag, and in particular to a method, medium and system for estimating electric quantity lost due to voltage sag. Background Art

[0002] Voltage sag refers to the instantaneous drop of the effective value of the power frequency voltage to 0.1 to 0.9 times the rated voltage value, which lasts for about 10ms to 1min. Voltage sag will cause sensitive equipment (such as inverters, AC contactors, programmable logic controllers, etc.) to stop working and cause certain economic losses.

[0003] When a user suffers from a voltage sag event, it may cause the user's sensitive equipment to stop operating, and even cause other auxiliary production equipment to shut down. The company's resumption of work and production plan takes about 1 to 24 hours. The existing technology does not accurately estimate the power loss caused by voltage sag events. Summary of the invention

[0004] The embodiments of the present invention provide a method, medium and system for estimating power loss due to voltage sag, so as to solve the problem of inaccurate estimation of power loss caused by voltage sag events in the prior art.

[0005] In a first aspect, a method for estimating power loss due to voltage sag is provided, comprising:

[0006] Establishing a daily reference power curve function for each category according to the measured daily historical active power values ​​of the users and the categories of the daily historical active power values;

[0007] Determine whether a voltage sag event occurs based on the voltage recording data;

[0008] If the voltage sag event occurs, determining whether the voltage sag event causes the user to lose power;

[0009] If the voltage sag event causes the user to lose power, a sag power curve function is established according to the active power value in the time period of the voltage sag event;

[0010] The voltage sag power loss of the user in the voltage sag event is calculated based on the sag power curve function and the daily reference power curve function of a type corresponding to the voltage sag event, so that operation and maintenance personnel can perform corresponding maintenance.

[0011] In a second aspect, a computer-readable storage medium is provided, on which computer program instructions are stored; when the computer program instructions are executed by a processor, the method for estimating the amount of electricity lost due to voltage sag as described in the embodiment of the first aspect above is implemented.

[0012] In a third aspect, a system for estimating power loss due to voltage sag is provided, comprising: a computer-readable storage medium as described in the embodiment of the second aspect above.

[0013] In this way, the embodiments of the present invention can more accurately estimate the amount of electricity lost by sensitive users in a single voltage sag event, so that operation and maintenance personnel can perform corresponding maintenance; the severity of the voltage sag event can also be determined based on the amount of electricity lost due to the voltage sag, and the power supply bus sag risk value can be evaluated based on the severity of the voltage sag event suffered by sensitive users, thereby providing data support for subsequent data mining based on the amount of electricity lost due to the voltage sag of users. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0015] Figure 1 It is a flow chart of a method for estimating power loss due to voltage sag according to an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] The embodiment of the present invention discloses a method for estimating power loss due to voltage sag. Specifically, Figure 1 As shown, the method for estimating the power loss due to voltage sag includes the following steps:

[0018] Step S1: according to the measured daily historical active power values ​​of the users and the classification of the daily historical active power values, a daily reference power curve function for each category is established.

[0019] Specifically, this step includes the following process:

[0020] (1) Obtain the daily historical active power value of the user measured within a first preset time range.

[0021] The daily historical active power value includes multiple active power values ​​measured every second preset time on the day. For example, if the second preset time in the embodiment of the present invention is 15 minutes, the measurement is performed every 15 minutes; for every day (24 hours), a total of 96 active power values ​​can be obtained. The daily historical active power value can be collected by the user power consumption information collection system.

[0022] The first preset time can be selected according to actual conditions, for example, one year, two years, etc. Under the condition of ensuring efficiency, a longer first preset time can be selected as much as possible to make the final result more accurate.

[0023] (2) Classify the daily historical active power values ​​according to the preset classification standards.

[0024] The preset classification standard is: daily historical active power values ​​with the same time index, season index and weather condition index are classified into the same category. The time index includes: weekdays, weekends and holidays. The season index includes: spring, summer, autumn and winter. The weather condition index includes: sunny, heavy rain and lightning.

[0025] (3) Calculate the average value of the active power values ​​of the same type measured at the same time for multiple days to obtain multiple active power means of the same type.

[0026] Taking the aforementioned daily collection of 96 active power values ​​as an example, for the same category, 96 active power averages can be obtained, that is, one active power average is obtained at each measurement moment.

[0027] (4) The Lagrange interpolation method is used to fit multiple active power means of the same type to obtain the daily benchmark power curve function of the same type.

[0028] Taking the above-mentioned 96 daily active power values ​​as an example, for the same type, y0, y1, ..., y 95 Represents 96 active power averages, x0, x1, ..., x 95 Indicates the measurement time corresponding to each active power mean value.

[0029] Lagrangian basis function l k The calculation formula of (x) is as follows:

[0030] Among them, k is 0, 1,..., 95.

[0031] The calculation formula of the Lagrange interpolation function is as follows:

[0032]

[0033] The obtained Lagrangian interpolation function is used as the daily reference power curve function.

[0034] Step S2: judging whether a voltage sag event occurs according to the voltage recording data.

[0035] Specifically, this step includes the following process:

[0036] (1) Obtain voltage recording data.

[0037] Specifically, the voltage recording data can be obtained through the power quality monitoring system. It should be understood that the voltage recording data is collected continuously. It should also be understood that since the duration of the voltage sag event is very short, the voltage recording data obtained in this step is generally the voltage recording data within one day, that is, the voltage recording data used in the embodiment of the present invention will not cross dates.

[0038] (2) The S-transform method is used to extract the mutation point time of the voltage recording data.

[0039] Specifically, the process is as follows:

[0040] ① Establish the S transformation matrix.

[0041] Specifically, the S transformation matrix is ​​as follows:

[0042]

[0043] Where T is the sampling interval of the voltage recording data, which can be obtained by the original sampling frequency of the voltage recording data ( f is the original sampling frequency of the voltage recording data), N is the number of sampling points of the voltage recording data, j is the preset discrete time point (which can be preset based on experience and is generally denser than the sampling points), n represents the multiple of the fundamental frequency, i represents the imaginary part of the complex number, and m is the summation number, which takes the values ​​of 0, 1, 2, ..., N-1.

[0044] ② Get the modular matrix of the S transform matrix.

[0045] Specifically, the modular matrix of the S transformation matrix is ​​as follows:

[0046]

[0047] The row vectors of the modulus matrix of the S transformation matrix represent the voltage amplitudes of the voltage recording data at different times of a frequency, and the column vectors of the modulus matrix of the S transformation matrix represent the voltage amplitudes of the voltage recording data at different frequencies at a time.

[0048] ③ Obtain the row vector corresponding to 10 times the fundamental frequency from the module matrix of the S transform matrix.

[0049] ④ If the voltage amplitude in the row vector corresponding to 10 times the fundamental frequency is greater than the second threshold, the moment corresponding to the voltage amplitude greater than the second threshold is determined as the mutation point moment.

[0050] Specifically, the second threshold value can be preset based on experience. For example, the second threshold value is preset to 0.4. Using the row vector corresponding to 10 times the fundamental frequency for judgment has a high accuracy rate and can reduce misjudgment and missed judgment.

[0051] (3) Calculate the effective value of the voltage in the time period between two adjacent mutation points.

[0052] The calculation of the effective value of voltage is a prior art, and its calculation formula is as follows: Where U is the effective value of voltage, T is one period, which is 0.02s, and u(t) is the voltage waveform curve function, which will not be described here.

[0053] (4) Determine whether the effective value of the voltage in the time period between two adjacent mutation points is less than a first threshold.

[0054] Specifically, the first threshold is 0.9 times the normal voltage effective value. The normal voltage effective value may adopt the voltage level of the power supply point. For example, if the voltage level of the power supply point is 10 kV, the normal voltage effective value is 10 kV.

[0055] (5) If the effective value of the voltage in the time period between two adjacent mutation point moments is less than the first threshold, it is determined that a voltage sag event occurs in the time period between the two adjacent mutation point moments, and the two adjacent mutation point moments are respectively determined as the start time and the end time of the voltage sag event in chronological order.

[0056] It should be understood that, for a section of voltage recording data, it is possible to determine that no voltage sag event occurred, it is possible to determine that one voltage sag event occurred, and it is also possible to determine that several voltage sag events occurred.

[0057] Step S3: If a voltage sag event occurs, determine whether the voltage sag event causes the user to lose power.

[0058] Specifically, this step includes the following process:

[0059] (1) Obtain the measured active power value at the next moment after the termination moment of the voltage sag event.

[0060] Unless otherwise specified, in the embodiment of the present invention, the measured active power values ​​are measured once every second preset time by the user power consumption information collection system to ensure the uniformity of all data. For example, if the second preset time is the aforementioned 15 minutes, the active power value 15 minutes after the end time of the voltage sag event is obtained.

[0061] (2) Determine whether the active power value at the next moment after the termination moment of the voltage sag event is less than a third threshold.

[0062] Specifically, the third threshold is 0.9 times the active power value at the next moment of the termination moment of the corresponding voltage sag event obtained by the selected daily reference power curve function.

[0063] (3) If the active power value at the next moment after the termination moment of the voltage sag event is less than the third threshold, it is determined that the voltage sag event causes power loss to the user, and this moment is recorded as the loss moment.

[0064] Step S4: If the voltage sag event causes the user to lose power, a sag power curve function is established according to the active power value in the time period of the voltage sag event.

[0065] This step specifically includes the following processes:

[0066] (1) According to the date, season and weather conditions of the voltage sag event, select the corresponding daily reference power curve function.

[0067] For example, if the voltage sag event occurs on a weekday, the season is summer, and the weather is sunny, then a type of daily reference power curve function corresponding to the above indicators is obtained.

[0068] (2) Taking the loss moment as the starting point, the active power value at the next moment measured is polled in sequence until the active power value at this moment is not less than the fourth threshold, and this moment is recorded as the recovery moment of the voltage sag event.

[0069] The active power value at the next moment obtained by sequential polling measurement refers to the next moment of the loss moment, the next moment of the next moment of the loss moment, and so on, and it is judged in sequence whether the active power value at the moment is less than the fourth threshold value. Similarly, the interval between adjacent moments is also every second preset time. Specifically, the fourth threshold value is 0.9 times the active power value corresponding to the moment obtained by the selected daily reference power curve function. For example, when judging the active power value at the next moment of the loss moment, the fourth threshold value compared therewith is 0.9 times the active power value at the next moment of the loss moment obtained by the selected daily reference power curve function.

[0070] (2) Obtain the active power value of the time period between the start time and the recovery time of the voltage sag event.

[0071] Among them, the active power value at the starting time is obtained by selecting the daily reference power curve function, and the active power values ​​at other times (i.e., the times within the time period between the starting time and the recovery time and the recovery time) are obtained by measurement, and are also measured every second preset time.

[0072] (3) The Lagrange interpolation method is used to fit the active power value of the time period between the start time and the recovery time of the voltage sag event to obtain the voltage sag power curve function.

[0073] The Lagrange interpolation method used in this step to obtain the voltage sag power curve function is consistent with the Lagrange interpolation method used in the aforementioned step S1 to obtain the user reference power curve function, which is specifically as follows:

[0074] Take z0, z1,…,z d represents each active power value of the time period between the start time and the recovery time of the voltage sag event, where z0 represents the active power value at the start time of the voltage sag event, z d Indicates the active power value at the time of recovery of the voltage sag event; a0, a1, ..., a d represents the time corresponding to each active power value in the time period between the start time and the recovery time of the voltage sag event, where a0 represents the start time of the voltage sag event, a d Indicates the recovery time of a voltage sag event.

[0075] Lagrangian basis function l r The calculation formula of (a) is as follows:

[0076] Among them, r is 0, 1,..., d.

[0077] The calculation formula of the Lagrange interpolation function is as follows:

[0078]

[0079] The obtained Lagrange interpolation function is used as the voltage sag power curve function.

[0080] Step S5: Calculate the power loss due to the voltage sag of the user in the voltage sag event according to the sag power curve function and a type of daily reference power curve function corresponding to the voltage sag event.

[0081] Specifically, this step includes the following process:

[0082] (1) In the time period between the start time and the recovery time of the voltage sag event, the curve obtained by the voltage sag power curve function is discretized every third preset time to obtain a number of discrete moments and corresponding voltage sag power values.

[0083] The third preset time can be selected based on experience. For example, the third preset time in the embodiment of the present invention is 1 minute. Discretization processing means that a single point on the voltage sag power curve is obtained every third preset time, and the horizontal coordinate of the point is the time, and the vertical coordinate is the voltage sag power value. It should be understood that the above time period includes the starting time and the recovery time.

[0084] (2) In the time period between the start time and the recovery time of the voltage sag event, at every third preset time, a curve obtained by a daily reference power curve function corresponding to a type of voltage sag event is discretized to obtain a number of discrete moments and corresponding daily reference active power values.

[0085] Similarly, this step obtains a single point on the daily reference power curve, the horizontal coordinate of which is the time, and the vertical coordinate is the daily reference active power value. The discrete moments of the obtained daily reference power curve correspond one-to-one to the discrete moments of the voltage sag power curve obtained above.

[0086] (3) Based on a number of discrete moments, the voltage sag power values ​​corresponding to the discrete moments, and the daily base active power values ​​corresponding to the discrete moments, the trapezoidal method is used to calculate the voltage sag power loss of the user in the voltage sag event.

[0087] Specifically, the calculation formula of the trapezoidal method is:

[0088]

[0089] Where ΔW represents the power loss caused by the voltage sag during the voltage sag event, P z (v) represents the daily reference active power value at the vth moment, P(v) represents the voltage sag power value at the vth moment, Δt represents the third preset time, and u represents the number of discrete moments.

[0090] Through the above process, the power loss of the user in the voltage sag event can be calculated, so that the operation and maintenance personnel can perform corresponding maintenance. In addition, the severity of the voltage sag event can be determined based on the power loss due to the voltage sag, and the power bus sag risk value can be evaluated based on the severity of the voltage sag event suffered by sensitive users, providing data support for subsequent data mining based on the power loss value of the user's voltage sag.

[0091] An embodiment of the present invention further discloses a computer-readable storage medium, on which computer program instructions are stored; when the computer program instructions are executed by a processor, the method for estimating power loss due to voltage sag as described in the above embodiment is implemented.

[0092] The embodiment of the present invention further discloses a system for estimating power loss due to voltage sag, comprising: a computer-readable storage medium as described in the above embodiment.

[0093] In summary, the embodiments of the present invention can more accurately estimate the amount of electricity lost by sensitive users in a single voltage sag event, so that operation and maintenance personnel can perform corresponding maintenance; the severity of the voltage sag event can also be determined based on the amount of electricity lost due to the voltage sag, and the power supply bus sag risk value can be evaluated based on the severity of the voltage sag event suffered by sensitive users, thereby providing data support for subsequent data mining based on the amount of electricity lost due to voltage sags by users.

[0094] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for estimating power loss due to voltage sag, characterized in that: include: According to the measured daily historical active power values ​​of the users and the classification of the daily historical active power values, a daily reference power curve function for each category is established; including: Acquire a daily historical active power value of the user measured within a first preset time range, wherein the daily historical active power value includes a plurality of active power values ​​measured at intervals of a second preset time on the same day; Classifying the daily historical active power values ​​according to a preset classification standard; Calculate the average value of the active power values ​​of the same type measured at the same time for multiple days to obtain multiple active power means of the same type; Using Lagrange interpolation method to fit multiple active power mean values ​​of the same type to obtain a daily reference power curve function of the same type; Determine whether a voltage sag event occurs based on the voltage recording data; If the voltage sag event occurs, determining whether the voltage sag event causes the user to lose power; If the voltage sag event causes the user to lose power, a sag power curve function is established according to the active power value in the time period of the voltage sag event; According to the sag power curve function and the daily reference power curve function of a type corresponding to the voltage sag event, the voltage sag power loss of the user in the voltage sag event is calculated to enable operation and maintenance personnel to perform corresponding maintenance; The step of calculating and obtaining the power loss of the user due to the voltage sag in the voltage sag event includes: In the time period between the start time and the recovery time of the voltage sag event, at every third preset time, discretizing the curve obtained by the voltage sag power curve function to obtain a number of discrete moments and corresponding voltage sag power values; In the time period between the start time and the recovery time of the voltage sag event, at every third preset time, a curve obtained by a daily reference power curve function corresponding to a type of voltage sag event is discretized to obtain a plurality of discrete moments and corresponding daily reference active power values; The voltage sag power loss of the user in the voltage sag event is calculated using the trapezoidal method according to a number of discrete moments, the voltage sag power values ​​corresponding to the discrete moments, and the daily base active power values ​​corresponding to the discrete moments.

2. The method for estimating power loss due to voltage sag according to claim 1, characterized in that: The step of determining whether a voltage sag event occurs comprises: Obtain voltage recording data; The S-transformation method is used to extract the moment of the sudden change point of the voltage recording data; Calculating the effective value of the voltage in the time period between two adjacent mutation points; Determine whether the effective value of the voltage in the time period between two adjacent mutation points is less than a first threshold; If the effective value of the voltage in the time period between two adjacent mutation point moments is less than the first threshold, it is determined that a voltage sag event occurs in the time period between the two adjacent mutation point moments, and the two adjacent mutation point moments are respectively determined as the start time and end time of the voltage sag event in chronological order.

3. The method for estimating power loss due to voltage sag according to claim 2, characterized in that: The step of extracting the mutation point time of the voltage recording data by using the S transform method comprises: Establish an S transformation matrix, wherein the S transformation matrix is ​​as follows: , T is the sampling interval of the voltage recording data, N is the number of sampling points of the voltage recording data, j is a preset discrete time point, n Indicates multiples of the fundamental frequency; Obtain a modulus matrix of the S transform matrix, wherein the modulus matrix of the S transform matrix is ​​as follows: , the row vectors of the module matrix of the S transformation matrix represent the voltage amplitudes of the voltage recording data at different times of a frequency, and the column vectors of the module matrix of the S transformation matrix represent the voltage amplitudes of the voltage recording data at different frequencies at a time; Obtaining a row vector corresponding to 10 times the fundamental frequency from the module matrix of the S transformation matrix; If the voltage amplitude in the row vector corresponding to the 10 times fundamental frequency is greater than a second threshold, the moment corresponding to the voltage amplitude greater than the second threshold is determined as the mutation point moment.

4. The method for estimating power loss due to voltage sag according to claim 2, characterized in that: The step of determining whether the voltage sag event causes the user to lose power includes: Acquire the measured active power value at the next moment after the termination moment of the voltage sag event; Determining whether the active power value at the next moment after the termination moment of the voltage sag event is less than a third threshold; If the active power value at the next moment after the termination moment of the voltage sag event is less than the third threshold, it is determined that the voltage sag event causes power loss to the user, and this moment is recorded as the loss moment.

5. The method for estimating power loss due to voltage sag according to claim 4, characterized in that: The step of establishing a temporary power reduction curve function comprises: According to the date, season and weather conditions of the voltage sag event, selecting the daily reference power curve function corresponding to a category; Taking the loss moment as the starting point, sequentially polling the measured active power value at the next moment until the active power value at this moment is not less than a fourth threshold, and recording this moment as the recovery moment of the voltage sag event; Obtaining the active power value of the time period between the start time and the recovery time of the voltage sag event, wherein the active power value at the start time is obtained by selecting the daily reference power curve function, and the active power values ​​at other times are obtained by measurement; The voltage sag power curve function is obtained by fitting the active power value of the time period between the start time and the recovery time of the voltage sag event using the Lagrange interpolation method.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer program instructions; when the computer program instructions are executed by the processor, the method for estimating the amount of electricity lost due to voltage sag according to any one of claims 1 to 5 is implemented.

7. A system for estimating power loss due to voltage sag, characterized in that: include: The computer readable storage medium of claim 6.

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