Three-phase voltage unbalance degree fast calculation method and system based on three-phase electric energy meter

Abstract

The application discloses a three-phase voltage unbalance degree fast calculation method and system based on a three-phase electric energy meter, the method constructs conversion function relations between positive sequence components, negative sequence components, zero sequence components and three-phase line voltages and three-phase phase voltages, and based on three-phase load compensation principles, zero sequence components and negative sequence components are used for vector synthesis to determine a compensation amount of three-phase voltage unbalance, and a three-phase voltage unbalance degree is defined based on a ratio of the compensation amount and the positive sequence components, so that the three-phase voltage unbalance degree can be calculated based on voltage measurement data (i.e. three-phase phase voltage data and three-phase line voltage data) of the three-phase electric energy meter, calculation accuracy is ensured, phase calculation is not needed in the whole process, calculation complexity is reduced, calculation efficiency is improved, the demand for computing power is low, real-time requirements of three-phase unbalance calculation can be well met, and the method can be well applied to electric energy meter terminals.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power quality monitoring, in particular, to a three-phase voltage unbalance degree fast calculation method and system based on a three-phase electric energy meter, an electronic device and a computer readable storage medium. BACKGROUND

[0002] In China, the low-voltage distribution network adopts three-phase four-wire system, that is, three live wires plus one neutral wire. Most of the residential electricity in China adopts single-phase load, that is, the single-phase line and the zero line bear the residential electricity load. With the rapid development of China's economy and the increasing improvement of people's living standards, household appliances are becoming more and more complex and diversified, which has caused the three-phase imbalance of residential low-voltage distribution areas in China to become increasingly serious, especially in rural areas. Due to the characteristics of wide distribution of electricity users, long power transmission lines and non-standard electricity use, the imbalance of China's power grid system is further aggravated. Among them, three-phase balance refers to a symmetrical system with equal three-phase voltage or current amplitude and 120° phase difference. If the three-phase amplitudes are different or the phases are not symmetrical, three-phase imbalance will occur, which will cause a series of hazards. The national standard clearly stipulates that under the condition of stable and continuous operation of the power grid, the three-phase imbalance of the voltage at all levels in the power grid cannot exceed 2%, and the three-phase imbalance cannot exceed 4% in a short time. The three-phase voltage imbalance caused by each electricity user at the point of common coupling cannot exceed 1.3%, and cannot exceed 2.6% in a short time. Therefore, how to calculate the three-phase imbalance is the basis for implementing the national standard and improving the power quality.

[0003] In addition, due to the continuous construction of new power systems, the three-phase imbalance of the distribution area is aggravated under the "light-storage-charging-load" scenario. At the same time, the State Grid requires smart electric energy meters to not only realize metering functions but also improve their power quality monitoring level. It is required that the real-time calculation of three-phase imbalance and daily extreme value statistics be realized in three-phase imbalance calculation. Therefore, the real-time requirement of three-phase imbalance calculation is high. The commonly used three-phase imbalance calculation method is based on phase sequence decomposition of three-phase imbalance, which needs to obtain negative sequence components, positive sequence components and zero sequence components through voltage phase sequence decomposition, and then calculate the three-phase imbalance of the user. For example, the ratio of the negative sequence vector to the positive sequence component of the voltage is used as the three-phase voltage imbalance. However, due to the dependence of phase calculation in the calculation process, the calculation complexity is high, the calculation time is long, and it cannot meet the real-time requirement of three-phase imbalance calculation. Moreover, it will occupy a large amount of calculation memory and require high calculation capacity. However, the electric energy meter itself has limited computing power, so it is difficult to apply to daily monitoring of three-phase imbalance at the electric energy meter end. SUMMARY

[0004] The application provides a three-phase voltage unbalance degree fast calculation method and system based on a three-phase electric energy meter, an electronic device and a computer readable storage medium, which guarantees calculation accuracy, does not need to perform phase calculation in the whole process, reduces calculation complexity, improves calculation efficiency, has low demand for computing power, can well meet real-time requirements of three-phase unbalance calculation, and can be well applied to electric energy meter ends.

[0005] According to one aspect of the application, a three-phase voltage unbalance degree fast calculation method based on a three-phase electric energy meter is provided, including the following contents:

[0006] Collect three-phase phase voltage data and three-phase line voltage data;

[0007] Respectively construct conversion function relationships between positive sequence components, negative sequence components and zero sequence components and three-phase line voltages and three-phase phase voltages;

[0008] Determine a compensation amount of three-phase voltage unbalance based on the zero sequence components and the negative sequence components, define a three-phase voltage unbalance degree based on a ratio of the compensation amount and the positive sequence components, and combine the conversion function relationships, the collected three-phase phase voltage data and three-phase line voltage data to calculate the three-phase voltage unbalance degree.

[0009] Further, the conversion function relationships between the positive sequence components, the negative sequence components and the zero sequence components and the three-phase line voltages and the three-phase phase voltages are as follows:

[0010] ;

[0011] ;

[0012] ;

[0013] Wherein, 、 and respectively represent the positive sequence components, the negative sequence components and the zero sequence components, 、 and represent the three-phase line voltages, 、 and represent the three-phase phase voltages.

[0014] Further, the three-phase voltage unbalance degree is calculated based on the following formula:

[0015] ;

[0016] Wherein, represents the three-phase voltage unbalance degree, represents the compensation amount of the three-phase voltage unbalance, , and respectively represent positive sequence component, negative sequence component and zero sequence component.

[0017] Further, the following is also included:

[0018] Based on the preset time window, the calculated value of the three-phase voltage unbalance degree is statistically processed to obtain a daily extreme value statistical result of the three-phase voltage unbalance degree.

[0019] Further, the process of statistically processing the calculated value of the three-phase voltage unbalance degree based on the preset time window to obtain the daily extreme value statistical result of the three-phase voltage unbalance degree includes the following:

[0020] The time window is set, and the mean and variance of the three-phase phase voltage and the three-phase line voltage in the time window are calculated, as well as the variance of the three-phase proportionality coefficient between the three-phase line voltage and the three-phase phase voltage;

[0021] Based on the variance of the three-phase line voltage and the variance of the three-phase proportionality coefficient, it is evaluated whether the three-phase voltage in the current time window is stable, and the calculation method of the three-phase voltage unbalance degree in the current time window is determined according to the evaluation result;

[0022] The time window is continuously slid on the daily voltage curve to obtain the daily extreme value statistical result of the three-phase voltage unbalance degree.

[0023] Further, if the variance of the three-phase line voltage and the variance of the three-phase proportionality coefficient are both less than a preset threshold, if yes, it is determined that the three-phase voltage in the current time window is stable, and the mean of the three-phase phase voltage and the three-phase line voltage in the current time window is used to calculate the three-phase voltage unbalance degree of the current time window, if no, it is determined that the three-phase voltage in the current time window is unstable, and the three-phase phase voltage data and the three-phase line voltage data of all voltage sampling points in the current time window are used to calculate the three-phase voltage unbalance degree of each voltage sampling point.

[0024] Further, in the process of continuously sliding the time window on the daily voltage curve, the following is also included:

[0025] It is judged whether the fluctuation rate of the voltage data in the current time window is less than or equal to a preset threshold, if yes, the sampling frequency of the voltage data is reduced, if no, the sampling frequency of the voltage data is increased.

[0026] In addition, the present application also provides a three-phase voltage unbalance degree fast calculation system based on a three-phase electric energy meter, comprising:

[0027] A three-phase voltage data acquisition module is used to acquire three-phase phase voltage data and three-phase line voltage data;

[0028] The conversion function relationship construction module is configured to construct conversion function relationships between the positive sequence component, the negative sequence component and the zero sequence component respectively and three-phase line voltages and three-phase phase voltages.

[0029] The three-phase voltage imbalance degree calculation module is configured to determine a compensation amount of the three-phase voltage imbalance based on the zero sequence component and the negative sequence component, define a three-phase voltage imbalance degree based on a ratio of the compensation amount and the positive sequence component, and calculate the three-phase voltage imbalance degree based on the conversion function relationships, the collected three-phase phase voltage data and the three-phase line voltage data.

[0030] In addition, the present application also provides an electronic device comprising a processor and a memory, wherein the memory stores a computer program, and the processor is configured to execute the steps of the method described above by calling the computer program stored in the memory.

[0031] In addition, the present application also provides a computer readable storage medium for storing a computer program for fast calculation of three-phase voltage imbalance degree based on a three-phase electric energy meter, wherein the computer program executes the steps of the method described above when running on a computer.

[0032] The present application has the following advantages:

[0033] The fast calculation method of three-phase voltage imbalance degree based on a three-phase electric energy meter constructs conversion function relationships between the positive sequence component, the negative sequence component and the zero sequence component respectively and three-phase line voltages and three-phase phase voltages based on the coupling relationship between the three-phase line voltages and the three-phase phase voltages, and expresses the three-phase voltage imbalance as a superposition of the zero sequence component and the negative sequence component based on the three-phase load compensation principle, determines a compensation amount of the three-phase voltage imbalance by vector synthesis based on the zero sequence component and the negative sequence component, and defines a three-phase voltage imbalance degree based on a ratio of the compensation amount and the positive sequence component, so that the three-phase voltage imbalance degree can be calculated based on the voltage measurement data (i.e. the three-phase phase voltage data and the three-phase line voltage data) of the three-phase electric energy meter, which not only ensures the calculation accuracy, but also reduces the calculation complexity and improves the calculation efficiency without phase calculation, has a lower demand for computing power, can well meet the real-time requirement of three-phase imbalance calculation, and can be well applied to the electric energy meter end.

[0034] In addition, the fast calculation system of three-phase voltage imbalance degree based on a three-phase electric energy meter also has the above advantages.

[0035] In addition to the above-described objects, features and advantages, the present application has other objects, features and advantages. The present application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0036] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, illustrate the preferred embodiment of the application and assist in

[0037] Figure 1 is a flowchart of a three-phase voltage unbalance degree fast calculation method based on a three-phase electric energy meter according to a preferred embodiment of the present application;

[0038] Figure 2 is another flowchart of a three-phase voltage unbalance degree fast calculation method based on a three-phase electric energy meter according to a preferred embodiment of the present application;

[0039] Figure 3 is a sub-flowchart of step S4 in Figure 2

[0040] Figure 4 is a module structure diagram of a three-phase voltage unbalance degree fast calculation system based on a three-phase electric energy meter according to another embodiment of the present application. DETAILED DESCRIPTION

[0041] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] With reference to Figure 1 , the preferred embodiment of the present application provides a three-phase voltage unbalance degree fast calculation method based on a three-phase electric energy meter, including the following contents:

[0043] Step S1: collecting three-phase phase voltage data and three-phase line voltage data;

[0044] Step S2: respectively constructing conversion function relationships between positive sequence components, negative sequence components and zero sequence components and three-phase line voltages and three-phase phase voltages;

[0045] Step S3: determining a compensation amount of three-phase voltage unbalance based on zero sequence components and negative sequence components, defining a three-phase voltage unbalance degree based on a ratio of the compensation amount and positive sequence components, and combining the conversion function relationships, the collected three-phase phase voltage data and three-phase line voltage data to calculate the three-phase voltage unbalance degree.

[0046] ​It can be understood that the three-phase voltage unbalance degree fast calculation method based on the three-phase electric energy meter in the embodiment is based on the coupling relationship between the three-phase line voltage and the three-phase phase voltage, constructs the conversion function relationship between the positive sequence component, the negative sequence component and the zero sequence component and the three-phase line voltage and the three-phase phase voltage respectively, and based on the three-phase load compensation principle, the three-phase voltage unbalance is expressed as the superposition of the zero sequence component and the negative sequence component, the compensation amount of the three-phase voltage unbalance is determined based on the vector synthesis of the zero sequence component and the negative sequence component, and the three-phase voltage unbalance degree is defined based on the ratio of the compensation amount and the positive sequence component, so that the three-phase voltage unbalance degree can be calculated based on the voltage measurement data of the three-phase electric energy meter (i.e. the three-phase phase voltage data and the three-phase line voltage data), which not only ensures the calculation accuracy, but also reduces the calculation complexity and improves the calculation efficiency without phase calculation, which has lower demand for computing power and can well meet the real-time requirements of three-phase unbalance calculation and can be well applied to the electric energy meter end.

[0047] In the step S1, in the three-phase four-wire low-voltage distribution area, the three-phase phase voltage data and the three-phase line voltage data of the area can be monitored by the three-phase electric energy total meter, wherein the three-phase phase voltage includes the phase voltage of A phase, the phase voltage of B phase and the phase voltage of C phase, and the three-phase line voltage includes the line voltage between A phase and B phase, the line voltage between B phase and C phase and the line voltage between C phase and A phase.

[0048] In addition, in the step S2, in the three-phase four-wire system, based on the coupling relationship between the three-phase line voltage and the three-phase phase voltage, it can be known that:

[0049] ;

[0050] wherein, , and represent the three-phase line voltage, respectively representing the line voltage vector between A phase and B phase, the line voltage vector between B phase and C phase, and the line voltage vector between C phase and A phase, , and represent the three-phase phase voltage, respectively representing the A phase voltage vector, the B phase voltage vector and the C phase voltage vector, , and represent the positive sequence component, the negative sequence component and the zero sequence component respectively, represents the size (effective value) and phase information (i.e. the phase is 30°) of the alternating voltage, represents the initial phase of the negative sequence component (or the corresponding alternating voltage sine quantity). In addition, based on the phase sequence decomposition principle, it can be known that: , , wherein, is a rotation operator, .

[0051] Then, by squaring both sides of the above equation, we obtain:

[0052] ;

[0053] Further, we can obtain: .

[0054] Next, based on the phase sequence decomposition principle, by calculating the positive sequence component and the negative sequence component, we can obtain:

[0055] ;

[0056] Taking the square root of both sides, we obtain:

[0057] ;

[0058] And Therefore, we can obtain:

[0059] ;

[0060] Solving the above equation again, since the positive sequence component is greater than the negative sequence component under normal circumstances, we can obtain:

[0061] ;

[0062] ;

[0063] Since the square sum of the positive sequence component, the negative sequence component, and the zero sequence component is 1 / 3 of the square sum of the three-phase phase voltage vector, i.e. Therefore, we can obtain:

[0064] .

[0065] At this point, the conversion function relationship between the square of the modulus of the positive sequence component, the negative sequence component, and the zero sequence component and the three-phase phase voltage and the three-phase line voltage has been established respectively.

[0066] It can be understood that the present application can be decomposed into three groups of symmetrical components with different phase angles based on any one group of asymmetric three-phase vectors: positive sequence component, negative sequence component and zero sequence component. Conversion function relationships between the positive sequence component, the negative sequence component and the zero sequence component and the three-phase phase voltage and the three-phase line voltage are constructed, so that in subsequent calculation of the three-phase voltage unbalance degree, the three-phase phase voltage and the three-phase line voltage are used to replace the positive sequence component, the negative sequence component and the zero sequence component for calculation, without the need to obtain the positive sequence component, the negative sequence component and the zero sequence component through phase calculation and then calculate the three-phase voltage unbalance degree, thereby eliminating the phase calculation process, making the calculation process of the three-phase voltage unbalance degree based only on voltage measurement data, reducing the calculation complexity and improving the calculation efficiency, and reducing the demand for computing power.

[0067] In addition, in the step S3, in a three-phase four-wire system, the negative sequence component and the zero sequence component are the main causes of imbalance, and based on the three-phase load compensation principle, the compensation target is: Therefore, the present application represents the three-phase voltage imbalance as the superposition of the zero sequence component and the negative sequence component, and in order to restore the balance of the system, compensation voltage vectors equal in magnitude and opposite in direction need to be applied to the zero sequence component and the negative sequence component respectively. The two compensation voltage vectors are independent vectors, and physically need to be offset at the same time to achieve complete balance. Therefore, the present application determines the compensation amount of the three-phase voltage imbalance based on the vector synthesis of the zero sequence component and the negative sequence component. According to the vector superposition principle in the power system, the size of the compensation amount is the square root of the sum of the squares of the zero sequence component and the negative sequence component, i.e. wherein, represents the compensation amount of the three-phase voltage imbalance.

[0068] Then, in order to make the three-phase voltage unbalance degree index applicable to different voltage levels and different systems, the compensation amount needs to be normalized. The present application normalizes the compensation amount using the positive sequence component as the reference value. On the one hand, the positive sequence component represents the ideal voltage level when the system is normally operating. On the other hand, normalizing with the positive sequence component as the denominator can form a dimensionless proportional index, which is convenient for unified comparison of different systems and different voltage levels. Therefore, the present application defines the three-phase voltage unbalance degree based on the ratio of the compensation amount to the positive sequence component, which can be expressed as: wherein, represents the three-phase voltage unbalance degree.

[0069] Next, combined with the three conversion function relationships constructed in step S2, the following can be obtained:

[0070] ;

[0071] In order to simplify the calculation, let , , wherein, A 、 B 、 C represents an intermediate variable, and it can be obtained that: .

[0072] Therefore, the three-phase voltage unbalance degree is finally calculated based on the following formula:

[0073] .

[0074] It can be understood that the present application is based on the three-phase load compensation principle, and represents the three-phase voltage unbalance as the superposition of the zero-sequence component and the negative-sequence component, determines the compensation amount of the three-phase voltage unbalance based on the vector synthesis of the zero-sequence component and the negative-sequence component, and defines the three-phase voltage unbalance degree based on the ratio of the compensation amount and the positive-sequence component, thereby ensuring the calculation accuracy of the three-phase voltage unbalance. In addition, the entire solving process only depends on the measured data of the three-phase phase voltage data and the three-phase line voltage data, without the need for complex phase calculation, and can well meet the real-time requirement of the three-phase unbalance calculation, and can also be well applied to the low-computing-power scene at the end of the electric energy meter.

[0075] Optionally, as shown in Figure 2 , the three-phase voltage unbalance degree fast calculation method based on the three-phase electric energy meter further includes the following contents:

[0076] Step S4: Based on the preset time window, data statistics is performed on the calculated value of the three-phase voltage unbalance degree, to obtain the daily extreme value statistical result of the three-phase voltage unbalance degree.

[0077] Specifically, according to the requirement of the power grid, the electric energy meter needs to support the daily frozen statistics of the three-phase voltage unbalance degree to obtain the daily three-phase voltage unbalance degree extreme value. At present, the commonly used statistical method is to obtain the voltage frozen data with a time interval of 3 seconds to calculate the three-phase voltage unbalance degree, and then based on the calculated value of the three-phase voltage unbalance degree every 3 seconds, the daily extreme value is obtained by statistics. However, the voltage monitoring frequency of the total electric energy meter is generally 50 Hz, that is, the voltage data of the transformer area is collected every 20 ms, and therefore, the voltage frozen data of 3 seconds corresponds to 150 cycles (20 ms per cycle) of the three-phase voltage unbalance degree calculation, that is, 150 three-phase voltage unbalance degree values need to be calculated every 3 seconds, and the calculation amount is still large. Therefore, in order to further reduce the calculation amount and improve the calculation efficiency, the present application performs data statistics on the calculated value of the three-phase voltage unbalance degree based on the preset time window, to obtain the daily extreme value statistical result of the three-phase voltage unbalance degree.

[0078] As shown in Figure 3 , the process of performing data statistics on the calculated value of the three-phase voltage unbalance degree based on the preset time window to obtain the daily extreme value statistical result of the three-phase voltage unbalance degree includes the following contents:

[0079] Step S41: Set a time window, and calculate the mean and variance of the three-phase phase voltages and the three-phase line voltages in the time window, and the variance of the three-phase proportionality coefficients between the three-phase line voltages and the three-phase phase voltages;

[0080] Step S42: Evaluate whether the three-phase voltages in the current time window are stable based on the variance of the three-phase line voltages and the variance of the three-phase proportionality coefficients, and determine the calculation mode of the three-phase voltage unbalance degree in the current time window according to the evaluation result;

[0081] Step S43: Continuously slide the time window on the daily voltage curve to obtain daily extreme value statistical results of the three-phase voltage unbalance degree.

[0082] Specifically, the length of the time window is set based on a preset time interval. For example, if the preset time interval for statistics is 3 seconds, the length of the time window is set to 3 seconds, and the voltage data is sampled by continuously sliding the time window on the daily voltage curve of the three-phase total energy meter. After each sliding, the three-phase phase voltage effective value and the three-phase line voltage effective value in the current time window can be obtained, where k represents the index position of the sampling data, the latest data index position is k , and the earliest data index position is k . N +1, N represents the data sequence length of the time window.

[0083] Then, the mean and variance of the three-phase phase voltages and the three-phase line voltages in the time window are calculated. For example, for the A-phase phase voltage, the calculation formula of the mean and variance is: wherein represents the mean of the A-phase phase voltage in the current time window, represents the variance of the A-phase phase voltage in the current time window, and the calculation formula of the mean and variance of the remaining phase voltages and the three-phase line voltages is basically the same, which will not be described here.

[0084] At the same time, the three-phase proportionality coefficient sequence between the three-phase line voltages and the three-phase phase voltages in the current time window is calculated, and the calculation formula is: 、 、 wherein 、 、 respectively represent the A-phase, B-phase and C-phase proportionality coefficients of the k th voltage sampling data in the current time window, and the variance of the three-phase proportionality coefficients in the current time window is calculated as .

[0085] Then, based on the variance of the three-phase line voltage and the variance of the three-phase proportionality coefficient, it is evaluated whether the three-phase voltage is stable in the current time window, and the calculation method of the three-phase voltage unbalance degree in the current time window is determined according to the evaluation result. Specifically, if the variance of the three-phase line voltage and the variance of the three-phase proportionality coefficient are both less than a preset threshold, i.e. and wherein, represents a line voltage variance threshold, represents a proportionality coefficient variance threshold, if yes, it is determined that the three-phase voltage in the current time window is stable, and the three-phase voltage unbalance degree of the current time window is calculated based on the average of the three-phase phase voltage and the three-phase line voltage in the current time window; if no, it is determined that the three-phase voltage in the current time window is unstable, and the three-phase voltage unbalance degree of each voltage sampling point is calculated based on the three-phase phase voltage data and the three-phase line voltage data of all voltage sampling points in the current time window.

[0086] wherein, when it is determined that the three-phase voltage in the current time window is stable, the three-phase voltage unbalance degree of the current time window is calculated based on the following formula:

[0087]

[0088] wherein, , , , , and are intermediate variables.

[0089] Finally, by continuously sliding the time window on the daily voltage curve of the three-phase total energy meter, the daily extreme value statistical result of the three-phase voltage unbalance degree can be obtained, so as to determine the daily extreme value of the three-phase voltage unbalance degree, for example, to find the maximum value and the minimum value of the three-phase voltage unbalance degree in each day.

[0090] It can be understood that the present application characterizes whether the three-phase voltage is numerically stable by three-phase line voltage variance and whether the three-phase phase angle is stable by three-phase proportion coefficient variance, so as to accurately evaluate whether the three-phase voltage is stable in the current time window. If the evaluation is stable, the mean values of the three-phase phase voltage and the three-phase line voltage in the current time window are directly used to calculate the three-phase voltage unbalance degree, that is, the three-phase voltage unbalance degree is calculated only once in a time window. Only when the evaluation is unstable, the voltage data (i.e. three-phase phase voltage data and three-phase line voltage data) of each voltage sampling point in the current time window is used to calculate the three-phase voltage unbalance degree of each voltage sampling point, that is, the three-phase voltage unbalance degree still needs to be calculated 150 times in a time window. Therefore, when the three-phase voltage stability is evaluated by the three-phase line voltage variance and the three-phase proportion coefficient variance, the three-phase voltage unbalance degree only needs to be calculated once in the time window, which greatly reduces the calculation amount compared with the prior art which needs to be calculated 150 times, and further improves the calculation efficiency.

[0091] In addition, in other embodiments of the present application, the length of the time window can also be set according to actual needs, for example, set to half of the preset time interval, i.e. 1.5s, but the time length of the time window needs to be less than the time length of the preset time interval.

[0092] Optionally, the process of continuously sliding the time window on the daily voltage curve also includes the following contents:

[0093] It is judged whether the fluctuation rate of the voltage data in the current time window is less than or equal to the preset threshold value. If yes, the sampling frequency of the voltage data is reduced, and if no, the sampling frequency of the voltage data is increased.

[0094] Specifically, when the time window is continuously slid on the daily voltage curve, it is judged whether the fluctuation rate (i.e. variance) of the three-phase phase voltage and the three-phase line voltage in the time window corresponding to the current sliding position is less than or equal to the preset threshold value (for example, 2%). If yes, it is determined that the system in the current time window is relatively stable, and the voltage data sampling frequency of the current time window can be reduced (for example, set to 1s / time). If no, it is determined that the system in the current time window is unstable, indicating that the load or voltage changes sharply, and the voltage data sampling frequency of the current time window is increased (for example, set to 20ms / time).

[0095] It can be understood that the present application dynamically adjusts the sampling frequency of the voltage data by evaluating the fluctuation rate of the voltage data in the time window, realizes the adaptive adjustment of the voltage data sampling frequency, and when the voltage data is stable, the sampling frequency can be reduced, which greatly reduces the amount of data to be processed under the premise of ensuring accuracy, and is beneficial to further improve the calculation efficiency.

[0096] In addition, the application also compares the three-phase voltage unbalance degree fast calculation method of the application with the calculation method specified in the existing IEC standard, wherein the three-phase voltage unbalance degree specified in the IEC standard is: that is, the three-phase voltage unbalance degree is the ratio of the negative sequence component to the positive sequence component, and the three-phase voltage unbalance degree needs to be calculated after the negative sequence component and the positive sequence component are calculated through phase calculation. The application compares the two from the aspects of accuracy and efficiency, and obtains the difference in accuracy between the fast calculation method of the application and the calculation method specified in the existing IEC standard as follows: As for the calculation efficiency, the fast calculation method of the application only takes 14 ms, while the IEC method takes more than 1.2 s, and in terms of memory occupation, the fast calculation method of the application is 22% of the IEC method. Therefore, compared with the existing IEC method, the fast calculation method of the application has little difference in accuracy, but greatly improves the calculation efficiency and greatly reduces the memory occupation, realizes efficient and fast calculation under the premise of ensuring calculation accuracy, can well meet the real-time requirement of three-phase unbalance calculation, reduces the demand for computing power, and can be well applied to the electric energy meter end.

[0097] In addition, as shown in Figure 4 Another embodiment of the application also provides a three-phase voltage unbalance degree fast calculation system based on a three-phase electric energy meter, which preferably adopts the three-phase voltage unbalance degree fast calculation method based on a three-phase electric energy meter as described above, and comprises:

[0098] a three-phase voltage data acquisition module, configured to acquire three-phase phase voltage data and three-phase line voltage data;

[0099] a conversion function relationship construction module, configured to construct conversion function relationships between the positive sequence component, the negative sequence component and the zero sequence component and the three-phase line voltage and the three-phase phase voltage, respectively;

[0100] a three-phase voltage unbalance degree calculation module, configured to determine a compensation amount of the three-phase voltage unbalance based on the zero sequence component and the negative sequence component, define the three-phase voltage unbalance degree based on the ratio of the compensation amount and the positive sequence component, and calculate the three-phase voltage unbalance degree in combination with the conversion function relationships, the acquired three-phase phase voltage data and three-phase line voltage data.

[0101] It can be understood that the three-phase voltage unbalance degree fast calculation system based on the three-phase electric energy meter in the embodiment is based on the coupling relationship between the three-phase line voltage and the three-phase phase voltage, constructs the conversion function relationship between the positive sequence component, the negative sequence component and the zero sequence component and the three-phase line voltage and the three-phase phase voltage respectively, and based on the three-phase load compensation principle, represents the three-phase voltage unbalance as the superposition of the zero sequence component and the negative sequence component, determines the compensation amount of the three-phase voltage unbalance based on the vector synthesis of the zero sequence component and the negative sequence component, and defines the three-phase voltage unbalance degree based on the ratio of the compensation amount and the positive sequence component, so that the three-phase voltage unbalance degree can be calculated based on the voltage measurement data (i.e. three-phase phase voltage data and three-phase line voltage data) of the three-phase electric energy meter, not only ensuring the calculation accuracy, but also reducing the calculation complexity and improving the calculation efficiency without phase calculation, and the power requirement is low, which can well meet the real-time requirement of three-phase unbalance calculation and be well applicable to the electric energy meter end.

[0102] In addition, the three-phase voltage unbalance degree fast calculation system based on the three-phase electric energy meter further comprises:

[0103] The daily extreme value statistical module is configured to statistically process the calculation values of the three-phase voltage unbalance degree based on a preset time window, and obtain a daily extreme value statistical result of the three-phase voltage unbalance degree.

[0104] In addition, another embodiment of the present application further provides an electronic device comprising a processor and a memory, wherein the memory stores a computer program, and the processor is configured to execute the steps of the method described above by calling the computer program stored in the memory.

[0105] In addition, another embodiment of the present application further provides a computer readable storage medium for storing a computer program for fast calculation of three-phase voltage unbalance degree based on a three-phase electric energy meter, wherein the computer program executes the steps of the method described above when running on a computer.

[0106] The computer readable storage medium can be a machine-readable storage medium, a machine-readable communication medium, or any combination thereof. Examples of the computer readable storage medium include, but are not limited to: an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, a portable computer diskette (magnetic), a RAM (Random Access Memory), a flash memory card, a volatile memory, a non-volatile memory, a ROM (Read Only Memory), an erasable programmable ROM (EPROM), a FLASH-EPROM, any other memory chip or cartridge, or any other tangible or non-transitory medium suitable for storing or transmitting computer software.

[0107] Those skilled in the art will appreciate that embodiments of the present application can be situated as methods, systems or computer program products. Accordingly, the present application can be embodied in the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application can be in the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk memory, CD-ROMs, optical storage media, etc.) embodying computer readable program code. The program code may

[0108] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions specified in the flowchart block or blocks or in conjunction with the flowcharts. Figure 1 The flowchart and / or block diagram in the drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart and / or block diagrams can represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical functions. It should also be noted that each block of the flowchart and / or block diagrams and that a flowchart and / or block diagram can represent a combination of Figure 1 The flowchart and / or block diagram in the drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart and / or block diagrams can represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical functions. It should also be noted that each block of the flowchart and / or block diagrams and that a flowchart and / or block diagram can represent a combination of

[0109] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0110] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0111] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0112] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rapid calculation method for three-phase voltage imbalance based on a three-phase energy meter, characterized in that, Includes the following: Collect three-phase phase voltage data and three-phase line voltage data; Construct conversion function relationships between the positive sequence component, negative sequence component, and zero sequence component and the three-phase line voltage and three-phase phase voltage, respectively; The compensation amount for three-phase voltage imbalance is determined based on the zero-sequence component and the negative-sequence component, and the degree of three-phase voltage imbalance is defined based on the ratio of the compensation amount to the positive-sequence component. Then, the degree of three-phase voltage imbalance is calculated by combining the conversion function relationship, the collected three-phase phase voltage data and three-phase line voltage data. The conversion function relationships between the positive-sequence components, negative-sequence components, and zero-sequence components and the three-phase line voltage and three-phase phase voltage are as follows: in, and These represent the positive-order component, the negative-order component, and the zero-order component, respectively. and Indicates the three-phase line voltage. and Indicates the three-phase phase voltage; The three-phase voltage imbalance is calculated based on the following formula: in, Indicates the degree of three-phase voltage imbalance. This indicates the compensation amount for three-phase voltage imbalance. and These represent the positive-order component, the negative-order component, and the zero-order component, respectively. Also includes the following: Based on a preset time window, the calculated values ​​of the three-phase voltage imbalance are statistically analyzed to obtain the daily extreme value statistical results of the three-phase voltage imbalance. The process of statistically analyzing the calculated values ​​of three-phase voltage imbalance based on a preset time window to obtain the daily extreme value statistical results of three-phase voltage imbalance includes the following: Set a time window and calculate the mean and variance of the three-phase phase voltage and the three-phase line voltage within the time window, as well as the variance of the three-phase proportionality coefficient between the three-phase line voltage and the three-phase phase voltage. The stability of the three-phase voltage within the current time window is assessed based on the variance of the three-phase line voltage and the variance of the three-phase proportional coefficient. The calculation method for the three-phase voltage imbalance within the current time window is determined based on the assessment results. If the variance of the three-phase line voltage and the variance of the three-phase proportional coefficient are both less than the preset threshold, the three-phase voltage within the current time window is determined to be stable. The three-phase voltage imbalance within the current time window is calculated using the average of the three-phase phase voltage and the three-phase line voltage within the current time window. If not, the three-phase voltage within the current time window is determined to be unstable. The three-phase voltage imbalance at each voltage sampling point is calculated using the three-phase phase voltage data and the three-phase line voltage data at all voltage sampling points within the current time window. By continuously sliding a time window on the daily voltage curve, the daily extreme values ​​of the three-phase voltage imbalance are obtained.

2. The method for rapid calculation of three-phase voltage imbalance based on a three-phase energy meter as described in claim 1, characterized in that, The process of continuously sliding along the daily voltage curve using a time window also includes the following: Determine whether the fluctuation rate of the voltage data within the current time window is less than or equal to a preset threshold. If yes, reduce the sampling frequency of the voltage data; otherwise, increase the sampling frequency of the voltage data.

3. A rapid calculation system for three-phase voltage imbalance based on a three-phase energy meter, employing the rapid calculation method for three-phase voltage imbalance based on a three-phase energy meter as described in claim 1, characterized in that... include: The three-phase voltage data acquisition module is used to acquire three-phase phase voltage data and three-phase line voltage data. The conversion function relationship construction module is used to construct the conversion function relationships between the positive sequence component, negative sequence component and zero sequence component and the three-phase line voltage and the three-phase phase voltage, respectively. The three-phase voltage unbalance calculation module is used to determine the compensation amount for the three-phase voltage unbalance based on the zero-sequence component and the negative-sequence component, and to define the three-phase voltage unbalance degree based on the ratio of the compensation amount to the positive-sequence component. Then, combined with the conversion function relationship, the collected three-phase phase voltage data and three-phase line voltage data, the three-phase voltage unbalance degree is calculated.

4. An electronic device, characterized in that, It includes a processor and a memory, wherein the memory stores a computer program, and the processor executes the steps of the method as described in claim 1 or 2 by calling the computer program stored in the memory.

5. A computer-readable storage medium for storing a computer program for rapidly calculating three-phase voltage imbalance based on a three-phase energy meter, characterized in that, The computer program performs the steps of the method as described in claim 1 or 2 when it is run on a computer.

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