Power grid quality monitoring method and monitoring system

Abstract

The invention provides a power grid quality monitoring method and system, and the method comprises the steps: obtaining the power data, collected by a sampling channel of an electric energy meter, of a power grid according to a preset monitoring period, and obtaining a sampling data set; at least one sampling channel is arranged in the electric energy meter; calculating each sampling data set based on a preset power grid quality data calculation method to obtain power grid quality data corresponding to each sampling channel; the power grid quality data comprises power grid quality parameters and quality parameter deviation values; judging whether the quality parameter deviation value is a preset deviation value or not; and if the quality parameter deviation value is not the preset deviation value, determining that the power grid quality is unqualified. In the mode, the power grid quality data applying the power grid quality can be calculated through the real-time electric power data, so that accurate monitoring and abnormal rapid identification of the power grid quality are realized, and the real-time performance of the electric energy quality, the power supply stability and the power grid operation safety are further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid quality monitoring, and in particular to a power grid quality monitoring method and monitoring system. Background Art

[0002] In the current power grid operation, power quality issues have a significant impact on power supply stability and user power safety. In particular, in industrial and sensitive equipment scenarios, real-time monitoring and accurate evaluation of power grid quality are particularly important. Existing processing methods usually rely on regular sampling and offline analysis, resulting in data processing delays and failure to identify anomalies in a timely manner. In addition, most systems lack the ability to comprehensively monitor multi-dimensional power quality indicators, making it difficult to meet high-standard grid operation requirements. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a method and system for monitoring the quality of a power grid, which can calculate the power grid quality data of the application power grid through real-time power data, thereby realizing accurate monitoring of the power grid quality and rapid identification of abnormalities, thereby improving the real-time nature of the power quality, power supply stability and safety of power grid operation.

[0004] In a first aspect, an embodiment of the present invention provides a method for monitoring power grid quality, comprising: acquiring power data of a power grid collected by a sampling channel of an electric energy meter according to a preset monitoring period to obtain a sampling data set; at least one sampling channel is provided in the electric energy meter; based on a preset power grid quality data calculation method, each sampling data set is calculated to obtain power grid quality data corresponding to each sampling channel; the power grid quality data includes power grid quality parameters and quality parameter deviation values; judging whether the quality parameter deviation value is a preset deviation value; if the quality parameter deviation value is not the preset deviation value, determining that the power grid quality is unqualified.

[0005] Furthermore, the step of obtaining the power data of the power grid collected by the sampling channel of the power meter according to the preset monitoring period and obtaining the sampling data set includes: obtaining the power data collected by each sampling channel according to the preset sampling period; calculating each power data based on the preset power quality index calculation method to obtain the power quality index data corresponding to the current sampling period; associating the power data of the current sampling period and its corresponding power quality index data and saving them in the sampling data set of the sampling channel.

[0006] Furthermore, the power data includes voltage data; the preset sampling period is the first sampling period; the power quality index data includes a voltage drop ratio and a voltage rise ratio; based on the power quality index calculation method, each power data is calculated to obtain the power quality index data corresponding to each sampling channel, including: based on the voltage data, calculating the periodic voltage root mean square of each sampling channel within the first sampling period, and determining the maximum value of the periodic voltage root mean square as the target periodic voltage root mean square; based on the preset voltage slow change index calculation formula and the target periodic voltage root mean square, calculating the voltage slow change index of the current first sampling period; based on the voltage slow change index, the preset voltage drop threshold and the voltage rise threshold, calculating the voltage drop ratio and the voltage rise ratio of the current first sampling period.

[0007] Furthermore, the power grid quality parameter is a voltage slow change index; the quality parameter deviation value is a voltage slow change deviation value; based on a preset power grid quality data calculation method, each sampling data set is calculated to obtain the power grid quality data corresponding to each sampling channel, including: obtaining a voltage drop ratio and a voltage rise ratio in the sampling data set, screening out the maximum value of the voltage drop ratio and the voltage rise ratio as the voltage slow change index; judging whether the voltage drop ratio and / or the voltage rise ratio of each first sampling period is greater than 1; if the voltage drop ratio and / or the voltage rise ratio is greater than 1, determining the first The voltage data of the sampling period is unqualified; the total number of unqualified voltage data is used as the number of unqualified voltage data in the preset monitoring period; the initial value of the number of unqualified voltage slow change index is 0; based on the number of unqualified voltage data and the total number of the first sampling period, the voltage data qualification rate of the preset monitoring period is obtained; it is determined whether the voltage data qualification rate is less than the preset first qualification rate threshold; if the voltage data qualification rate is greater than or equal to the preset first qualification rate threshold, the voltage slow change deviation value is determined to be the preset deviation value; if the qualification rate is less than the preset first qualification rate threshold, the voltage slow change deviation value is determined to be the voltage slow change index-1.

[0008] Furthermore, the power data includes voltage data; the preset sampling period is the first sampling period; the power quality index data includes a voltage total harmonic distortion ratio; based on the power quality index calculation method, each power data is calculated to obtain the power quality index corresponding to each sampling channel, including: based on the voltage data, calculating the voltage total harmonic distortion of each sampling channel within the first sampling period, and determining the maximum value of the voltage total harmonic distortion as the target voltage total harmonic distortion; based on the target voltage total harmonic distortion and the preset harmonic distortion threshold, calculating the voltage total harmonic distortion ratio of the current first sampling period.

[0009] Furthermore, the power grid quality parameter is a voltage distortion index; the quality parameter deviation value is a voltage distortion deviation value; based on a preset power grid quality data calculation method, each sampling data set is calculated to obtain the steps of power grid quality data corresponding to each sampling channel, including: obtaining a voltage total harmonic distortion ratio in the sampling data set, and screening out the maximum value of the voltage total harmonic distortion ratio as the voltage distortion index; judging whether the voltage distortion index is greater than 1; if the voltage distortion index is less than or equal to 1, determining the voltage distortion deviation value to be a preset deviation value; if the voltage distortion index is greater than 1, determining the voltage distortion deviation value to be a voltage slow change index -1.

[0010] Furthermore, when the electric energy meter is a three-phase electric energy meter, the electric power data includes three-phase voltage data; the preset sampling period is the first sampling period; the electric energy quality index data includes the negative-sequence asymmetry coefficient; based on the electric energy quality index calculation method, each electric power data is calculated to obtain the electric energy quality index corresponding to each sampling channel, including: based on the three-phase voltage data, calculating the negative-sequence voltage root mean square and the positive-sequence voltage root mean square within the first sampling period; taking the ratio of the negative-sequence voltage root mean square to the positive-sequence voltage root mean square as the negative-sequence asymmetry coefficient.

[0011] Furthermore, the power grid quality parameter is a voltage asymmetry index; the quality parameter deviation value is a voltage asymmetry deviation value; based on a preset power grid quality data calculation method, each sampling data set is calculated to obtain the power grid quality data corresponding to each sampling channel, including: obtaining the negative sequence asymmetry coefficient in the sampling data set; based on the negative sequence asymmetry coefficient, determining the root mean square of the negative sequence asymmetry coefficient of the preset monitoring period, and setting the ratio of the root mean square of the negative sequence asymmetry coefficient to the preset root mean square threshold as the voltage asymmetry index; judging whether the negative sequence asymmetry coefficient of each first sampling period is greater than the preset coefficient threshold; if the negative sequence asymmetry coefficient is greater than the preset coefficient threshold, determining that the three-phase voltage data of the first sampling period is unqualified; and taking the total number of unqualified three-phase voltage data as the three-phase voltage data of the preset monitoring period. The number of unqualified phase voltage data; the initial value of the number of unqualified three-phase voltage data is 0; based on the number of unqualified three-phase voltage data and the total number of the first sampling period, the qualified rate of the three-phase voltage data of the preset monitoring period is obtained; it is determined whether the qualified rate of the three-phase voltage data is less than the preset second qualified rate threshold; if the qualified rate of the three-phase voltage data is less than the preset second qualified rate threshold, it is determined whether the voltage asymmetry index is greater than 1; if the voltage asymmetry index is less than or equal to 1, the voltage asymmetry deviation value is determined to be the preset deviation value; if the voltage asymmetry index is greater than 1, the voltage asymmetry deviation value is determined to be the voltage asymmetry index-1; if the qualified rate of the three-phase voltage data is greater than or equal to the preset second qualified rate threshold, it is determined whether the voltage asymmetry index is 0; if the voltage asymmetry index is 0, the voltage asymmetry deviation value is determined to be the preset deviation value.

[0012] Further, when the electric energy meter is a three-phase electric energy meter, the electric power data includes three-phase voltage data; the preset sampling period is the first sampling period and the second sampling period; the first sampling period is less than the second sampling period; the electric energy quality index data includes a long-term flicker value; based on the electric energy quality index calculation method, each electric power data is calculated to obtain the electric energy quality index corresponding to each sampling channel, including: based on the instantaneous flicker value in the three-phase voltage data, the short-term flicker value of the first sampling period is calculated; the short-term flicker value is the root mean square of the instantaneous flicker value; based on the short-term flicker value corresponding to each first sampling period in the second sampling period, the long-term flicker value of the second sampling period is calculated; the calculation formula corresponding to the long-term flicker value is as follows: Among them, P lt is the long-term flicker value, n is the number of short-term flicker values, P st,i It is the short-time flicker value corresponding to each first sampling period.

[0013] Furthermore, the power grid quality parameter is the voltage flicker fluctuation rate; the quality parameter deviation value is the voltage flicker deviation value; based on the preset power grid quality data calculation method, each sampling data set is calculated to obtain the power grid quality data corresponding to each sampling channel, including: obtaining the long-term flicker value in the sampling data set, screening out the maximum value of the long-term flicker value as the target long-term flicker value; setting the ratio of the long-term flicker value to the preset allowable level threshold as the voltage flicker fluctuation rate; judging whether the long-term flicker value of each second sampling period is greater than the preset flicker value threshold; if the long-term flicker value is greater than the flicker value threshold, determining the second sampling period The instantaneous flicker value of the sampling period is unqualified; the total number of unqualified instantaneous flicker values ​​is used as the number of unqualified instantaneous flicker values ​​of the preset monitoring period; the initial value of the number of unqualified instantaneous flicker values ​​is 0; based on the number of unqualified instantaneous flicker values ​​and the total number of the second sampling period, the instantaneous flicker value pass rate of the preset monitoring period is obtained; it is determined whether the instantaneous flicker value pass rate is less than the preset third pass rate threshold; if the instantaneous flicker value pass rate is less than the preset third pass rate threshold, the voltage flicker deviation value is determined to be the voltage flicker fluctuation rate-1; if the instantaneous flicker value pass rate is greater than or equal to the preset third pass rate threshold, the voltage flicker deviation value is determined to be the preset deviation value.

[0014] In a second aspect, an embodiment of the present invention provides a system for monitoring power grid quality, comprising: a monitoring module, used to obtain power data of the power grid collected by a sampling channel of an electric energy meter according to a preset monitoring period, and obtain a sampling data set; at least one sampling channel is provided in the electric energy meter; a power grid quality data calculation module, used to calculate each sampling data set based on a preset power grid quality data calculation method, and obtain power grid quality data corresponding to each sampling channel; the power grid quality data includes power grid quality parameters and quality parameter deviation values; a power grid quality judgment module, used to judge whether the quality parameter deviation value is a preset deviation value; the power grid quality judgment module is also used to determine that the power grid quality is unqualified if the quality parameter deviation value is not the preset deviation value.

[0015] A method and system for monitoring power grid quality provided by an embodiment of the present invention include: obtaining power grid power data collected by a sampling channel of an electric energy meter according to a preset monitoring cycle to obtain a sampling data set; at least one sampling channel is provided in the electric energy meter; based on a preset power grid quality data calculation method, each sampling data set is calculated to obtain power grid quality data corresponding to each sampling channel; the power grid quality data includes power grid quality parameters and quality parameter deviation values; judging whether the quality parameter deviation value is a preset deviation value; if the quality parameter deviation value is not a preset deviation value, determining that the power grid quality is unqualified. In this manner, power grid quality data of the application power grid quality can be obtained by calculating real-time power data, thereby realizing accurate monitoring of power grid quality and rapid identification of abnormalities, thereby improving the real-time nature of power quality, power supply stability, and safety of power grid operation.

[0016] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0017] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A flow chart of a method for monitoring power grid quality provided by an embodiment of the present invention;

[0020] Figure 2 A flow chart of a method for acquiring a sample data set provided by an embodiment of the present invention;

[0021] Figure 3 A flow chart of a method for obtaining a voltage drop ratio and a voltage rise ratio provided in an embodiment of the present invention;

[0022] Figure 4 A flow chart of a method for obtaining a voltage slow change index and a voltage slow change deviation value provided by an embodiment of the present invention;

[0023] Figure 5 A flow chart of a method for obtaining a voltage total harmonic distortion ratio provided by an embodiment of the present invention;

[0024] Figure 6 A flow chart of a method for obtaining a voltage distortion index and a voltage distortion deviation value provided by an embodiment of the present invention;

[0025] Figure 7 A flow chart of a method for obtaining a negative sequence asymmetry coefficient provided by an embodiment of the present invention;

[0026] Figure 8 A flow chart of a method for obtaining a voltage asymmetry index and a voltage asymmetry deviation value provided by an embodiment of the present invention;

[0027] Fig. 9 A flow chart of a method for obtaining a voltage flicker fluctuation rate and a voltage flicker deviation value provided by an embodiment of the present invention;

[0028] Fig.10 A schematic diagram of a power grid quality monitoring system provided in an embodiment of the present invention.

[0029] Icons: 1- monitoring module; 2- power grid quality data calculation module; 3- power grid quality judgment module. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. 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.

[0031] To facilitate understanding of this embodiment, the embodiment of the present invention is described in detail below.

[0032] Embodiment 1:

[0033] Figure 1 A flow chart of a method for monitoring power grid quality provided by an embodiment of the present invention.

[0034] The method for monitoring the quality of a power grid in the embodiment of the present invention can be used on terminal devices such as electric energy meters and concentrators.

[0035] Reference Figure 1 , the monitoring methods of power grid quality include:

[0036] Step S101, according to a preset monitoring cycle, power data of the power grid collected by a sampling channel of the power meter is acquired to obtain a sampling data set; at least one sampling channel is provided in the power meter.

[0037] Here, the preset monitoring period is pre-set according to the actual situation, and can be set to one week. Before the next monitoring period starts, the sample data set saved in the current monitoring period is deleted.

[0038] The electric energy meter is connected to the power grid. The electric energy meter can be a single-phase electric energy meter or a three-phase electric energy meter. When the electric energy meter is a single-phase electric energy meter, the sampling channel is one. When the electric energy meter is a three-phase electric energy meter, the sampling channels are three.

[0039] The sampling channels in the electric energy meter are used to collect different types of data, such as key parameters such as voltage, current, frequency and harmonics. Each channel corresponds to a specific monitoring target.

[0040] In one embodiment, referring to Figure 2 , the steps of step S102 include:

[0041] Step S201: acquiring power data collected by each sampling channel according to a preset sampling period.

[0042] Here, the preset sampling period can be pre-set according to the actual situation. The selection of the sampling period should take into account the fluctuation characteristics of the power grid and the storage space requirements to ensure that the data covers the dynamic characteristics of the power grid. Based on the different characteristics of power data, the sampling period includes a first sampling period and a second sampling period. The first sampling period can be set to 10 minutes, and the second sampling period can be set to 120 minutes.

[0043] The electric energy meter collects power signals through sensors and analog-to-digital conversion circuits. Use high-precision sensors (such as voltage transformers and current transformers) to collect real-time power signals. Filter and convert the collected analog signals to digital sampling data. The sampling data is temporarily stored in the memory of the electric energy meter for subsequent processing.

[0044] Step S202, based on a preset power quality index calculation method, each power data is calculated to obtain power quality index data corresponding to the current sampling period.

[0045] Here, the sampled data is preprocessed (such as normalization, noise filtering, etc.), the corresponding power quality calculation algorithm is called, the calculation of the index is gradually completed, and the power quality index data is generated according to the statistical data within the sampling period.

[0046] When the electric energy meter is a single-phase electric energy meter, the electric energy quality index data includes at least one of a voltage drop ratio, a voltage rise ratio and a voltage total harmonic distortion ratio.

[0047] When the electric energy meter is a three-phase electric energy meter, the electric energy quality index data includes at least one of a voltage drop ratio, a voltage rise ratio, a voltage total harmonic distortion ratio, a negative sequence asymmetry coefficient and a long-term flicker value.

[0048] Step S203: associate the power data of the current sampling period and its corresponding power quality indicator data and save them in the sampling data set of the sampling channel.

[0049] Here, the original power data of each sampling period is associated with the calculated power quality index data and stored. The association relationship can be identified by a timestamp or a sampling channel ID.

[0050] Step S102, based on a preset power grid quality data calculation method, each sampling data set is calculated to obtain power grid quality data corresponding to each sampling channel; the power grid quality data includes power grid quality parameters and quality parameter deviation values.

[0051] Here, when the electric energy meter is a single-phase electric energy meter, the grid quality parameter is the voltage slow change index and / or the voltage distortion index; the quality parameter deviation value corresponding to the voltage slow change index is the voltage slow change deviation value; the quality parameter deviation value corresponding to the voltage distortion index is the voltage distortion deviation value.

[0052] When the electric energy meter is a three-phase electric energy meter, the grid quality parameter is at least one of the voltage slow change index, the voltage distortion index, the voltage asymmetry index and the voltage flicker fluctuation rate; the quality parameter deviation value corresponding to the voltage slow change index is the voltage slow change deviation value; the quality parameter deviation value corresponding to the voltage distortion index is the voltage distortion deviation value; the quality parameter deviation value corresponding to the voltage asymmetry index is the voltage asymmetry deviation value; the quality parameter deviation value corresponding to the voltage flicker fluctuation rate is the voltage flicker deviation value.

[0053] In one embodiment, the power data includes voltage data; the preset sampling period is the first sampling period; and the power quality index data includes a voltage drop ratio and a voltage rise ratio. Figure 3 , the steps of step S202 include:

[0054] Step S301: Based on the voltage data, the periodic voltage root mean square of each sampling channel in the first sampling period is calculated, and the maximum value of the periodic voltage root mean square is determined as the target periodic voltage root mean square.

[0055] Here, all voltage data within the current first sampling period (10 minutes) are obtained.

[0056] Abnormal voltage data (such as electromagnetic interference or noise) is filtered and preprocessed to ensure the accuracy of the calculation results.

[0057] The voltage root mean square (RMS) is an effective value of an AC signal, which reflects the effective power of the AC signal and is equivalent to the power of a DC signal.

[0058] In multi-channel acquisition, the voltage RMS and periodic voltage RMS can be grouped by phase for statistics (such as independent calculation of phases A, B, and C), and the target periodic voltage RMS is the maximum value of the periodic voltage RMS corresponding to the three phases.

[0059] The cycle voltage root mean square is the root mean square of the instantaneous voltage value in the first sampling cycle. The target cycle voltage root mean square reflects the maximum voltage effective value of the power grid in the current first sampling cycle.

[0060] Specifically, the periodic voltage RMS is:

[0061] The cycle voltage RMS is used to quantify the effective value of the voltage within a cycle and reflects the average energy level of the voltage.

[0062] The target cycle voltage RMS is defined as the cycle voltage RMS of the maximum value among multiple sampling channels, which is used for the subsequent calculation of the voltage slow change index.

[0063] Step S302, based on a preset voltage slow change index calculation formula and a target period voltage root mean square, calculate and obtain the voltage slow change index of the current first sampling period.

[0064] Here, the voltage slow change index of the current first sampling period is: Among them, U C is the rated voltage, τ ΔU is the voltage slow change index, and U is the period RMS voltage root mean square (the voltage mean value within the sampling period).

[0065] Step S303 , based on the voltage slow change index, the preset voltage drop threshold and the voltage rise threshold, the voltage drop ratio and the voltage rise ratio of the current first sampling period are calculated.

[0066] Here, the voltage drop threshold and the voltage rise threshold are preset according to actual conditions and may be set to 10%.

[0067] Voltage drop ratio U sag And the voltage rise ratio U swell Used to characterize voltage fluctuations.

[0068] Specifically, Among them, τ ΔU,sag and τ ΔU,swell The threshold is configurable and can be set to 10%.

[0069] In one embodiment, the power grid quality parameter is a voltage slow change index; the quality parameter deviation value is a voltage slow change deviation value. Figure 4 , the steps of step S102 include:

[0070] Step S401, obtaining a voltage drop ratio and a voltage rise ratio in a sample data set, and screening out a maximum value of the voltage drop ratio and the voltage rise ratio as .

[0071] Here, the calculated voltage drop ratio and voltage rise ratio are extracted from the sampled data set within each sampling period.

[0072] The sag ratio and swell ratio calculate the degree to which the voltage drops or rises, respectively, relative to its nominal value.

[0073] The drop ratio and the rise ratio in each first sampling period are compared, and the larger value is selected as the voltage slow change index of the current sampling period.

[0074] If the voltage slowly changes indices over multiple sampling periods are similar, a smoother change trend can be calculated using the weighted average method.

[0075] For different sampling channels, the slow-changing indexes are recorded and compared respectively to form a multi-dimensional analysis.

[0076] Voltage slow change index: W1=max(U sag ,U swell ).

[0077] Step S402 , determining whether the voltage drop ratio and / or the voltage rise ratio of each first sampling period is greater than 1.

[0078] Here, when the voltage drop ratio and rise ratio are greater than 1, it indicates that the voltage fluctuation exceeds the allowable range and may affect the operation of the equipment and the power grid.

[0079] Step S403, if the voltage drop ratio and / or the voltage rise ratio is greater than 1, determine that the voltage data of the first sampling period is unqualified; take the total number of unqualified voltage data as the number of unqualified voltage data in the preset monitoring period; the initial value of the number of unqualified voltage slow change index is 0.

[0080] Here, for the voltage data judged as unqualified, the corresponding sampling period, sampling channel and unqualified type (such as drop or rise exceeding the limit) are recorded. Within a preset monitoring period (such as one week), the unqualified voltage data of all sampling periods are accumulated to obtain the number of unqualified times.

[0081] Step S404, obtaining a voltage data pass rate of a preset monitoring period based on the number of unqualified voltage data and the total number of the first sampling period.

[0082] Here, the voltage data qualification rate refers to the proportion of voltage data within the allowable range during the monitoring period.

[0083] Step S405, determining whether the voltage data pass rate is less than a preset first pass rate threshold.

[0084] Here, the voltage data pass rate is compared with a preset first pass rate threshold (eg, 95%).

[0085] If the qualified rate is lower than the threshold, it is determined that the voltage fluctuation in the current monitoring period does not meet the quality requirements.

[0086] The threshold can be adjusted according to the application scenario. For example, industrial equipment may require a higher pass rate (such as 98%), while ordinary residential users can relax it appropriately.

[0087] Step S406 , if the voltage data pass rate is greater than or equal to a preset first pass rate threshold, determining the voltage slowly changing deviation value to be a preset deviation value.

[0088] Here, if the qualified rate meets the requirements, the voltage fluctuation is considered to be within the normal range, and the voltage slow change deviation value is set to the system default value (such as 0). The record of normal deviation value can be used as a reference for the health status of the power grid. The deviation value can be defined in multiple levels according to the specific operating conditions, which is used to refine the evaluation of the health status of the power grid.

[0089] Step S407 , if the qualified rate is less than the preset first qualified rate threshold, determining the voltage slow change deviation value as the voltage slow change index-1.

[0090] Here, if the qualified rate is less than the preset first qualified rate threshold, the deviation value is the voltage slow change index minus 1. The deviation value reflects the severity of the voltage fluctuation exceeding the standard.

[0091] Specifically, the pass rate calculation method is as follows: Where, T(totle): the total number of measurements in the current week, T(failed): the total number of unqualified records in the current week, and ΔT is the qualified rate of measurements in the current week.

[0092] The voltage slowly changes and the deviation value is: Wherein, ΔW1 is the voltage slowly changing deviation value.

[0093] In one embodiment, the power data includes voltage data; the preset sampling period is the first sampling period; and the power quality indicator data includes a voltage total harmonic distortion ratio. Figure 5 , the steps of step S202 include:

[0094] Step S501 : Based on the voltage data, the voltage total harmonic distortion of each sampling channel in the first sampling period is calculated, and the maximum value of the voltage total harmonic distortion is determined as the target voltage total harmonic distortion.

[0095] Here, total harmonic distortion is a measure of the distortion of the harmonic components in the voltage waveform relative to the fundamental component.

[0096] The sampled voltage data is Fourier transformed and decomposed into the fundamental wave and each harmonic component. The fundamental wave and harmonic components are extracted using the fast Fourier transform (FFT). The RMS value of each harmonic component is calculated. The harmonic RMS value is substituted into the formula to calculate the total harmonic distortion of the voltage of each sampling channel.

[0097] The voltage total harmonic distortions calculated by all sampling channels in the current first sampling period are compared, and the maximum value is selected as the target total harmonic distortion.

[0098] The sampled signal is preprocessed using a window function (such as a Hanning window or a Hamming window) to reduce the impact of spectrum leakage on harmonic analysis.

[0099] If there are multiple channels with similar harmonic distortion values, the related channels can be marked at the same time for subsequent analysis.

[0100] Step S502: Based on the target voltage total harmonic distortion and a preset harmonic distortion threshold, a voltage total harmonic distortion ratio of the current first sampling period is calculated.

[0101] Here, the total harmonic distortion ratio is used to quantify the relative relationship between the current total harmonic distortion and the preset allowable level.

[0102] Pre-set harmonic distortion threshold (can be set to 5% or other value).

[0103] Adjust the harmonic distortion threshold according to the application scenario and the sensitivity of the electrical equipment. For example:

[0104] For industrial users, a lower threshold (such as 3%) can be set.

[0105] For ordinary users, a higher threshold (such as 8%) may be allowed.

[0106] Specifically, the voltage total harmonic distortion is: Among them, U1 is the fundamental voltage, TTHD u is the total voltage harmonics.

[0107] The voltage total harmonic distortion ratio is: Among them, TTHD max The maximum voltage total harmonic distortion value in the current cycle, TTHD levelallowed is a configurable threshold for the allowed level (settable to 8%).

[0108] In one embodiment, the power grid quality parameter is a voltage distortion index; the quality parameter deviation value is a voltage distortion deviation value, referring to Figure 6 , the steps of step S202 include:

[0109] Step S601 : obtaining voltage total harmonic distortion ratios in a sampled data set, and screening out the maximum value of the voltage total harmonic distortion ratios as a voltage distortion index.

[0110] Here, the voltage total harmonic distortion ratio is an indicator used to measure the harmonic distortion of the power grid, which is defined as the total harmonic distortion value.

[0111] Compare the harmonic distortion ratios of each channel and select the maximum value as the voltage distortion index.

[0112] This maximum value represents the most serious harmonic distortion of the power grid in the current sampling period.

[0113] Step S602, determining whether the voltage distortion index is greater than 1.

[0114] Here, the voltage distortion index is greater than 1, which means that the harmonic distortion exceeds the preset allowable range, indicating that the grid voltage quality does not meet the standard.

[0115] Step S603: if the voltage distortion index is less than or equal to 1, determining the voltage distortion deviation value to be a preset deviation value.

[0116] Here, when the distortion index is normal, the deviation value is set to the system default preset deviation value (such as 0). This indicates that the power grid harmonic distortion level meets the quality standard in the current sampling period.

[0117] Step S604: if the voltage distortion index is greater than 1, determine the voltage distortion deviation value as the voltage slow change index -1.

[0118] Here, when the distortion index exceeds the standard, the voltage distortion deviation value is set to the voltage slow change index minus 1. The distortion index, deviation value and related information are stored in a data set.

[0119] Specifically, the voltage distortion index is: W2 = max(W TTHDU ), where W2 is the voltage distortion indicator.

[0120] The voltage distortion deviation value is:

[0121] For example: U=285V, U1=230V. ΔW2=W2-1=8.14.

[0122] In one embodiment, when the electric energy meter is a three-phase electric energy meter, the electric power data includes three-phase voltage data; the preset sampling period is the first sampling period; and the electric energy quality index data includes a negative sequence asymmetry coefficient. Figure 7 , the steps of step S202 include:

[0123] Step S701, based on the three-phase voltage data, calculate and obtain the negative sequence voltage root mean square and the positive sequence voltage root mean square in the first sampling period.

[0124] Here, positive sequence component: represents the fundamental component of the voltage in the three-phase symmetrical component (ideal three-phase symmetrical system).

[0125] Negative sequence component: represents the asymmetric component in the three-phase voltage, usually caused by load unbalance or grid disturbance.

[0126] The positive sequence voltage RMS value represents the ideal voltage effective value.

[0127] The negative sequence voltage RMS value indicates the degree of voltage imbalance.

[0128] Specifically, the negative sequence voltage RMS calculation method is as follows: Where VNSN is the instantaneous asymmetry coefficient of the negative sequence component, VNSN 10min is the RMS value of the negative sequence component within a 10-minute period.

[0129] Step S702: taking the ratio of the negative sequence voltage root mean square to the positive sequence voltage root mean square as the negative sequence asymmetry coefficient.

[0130] Here, the negative sequence asymmetry coefficient reflects the degree of imbalance of the three-phase voltage. The higher the coefficient, the more serious the asymmetry of the power grid.

[0131] If there is a high negative sequence asymmetry coefficient in multiple channels, further analysis can be performed to find the specific cause of the asymmetry, such as load imbalance or short circuit fault.

[0132] Statistics are taken for multiple sampling periods, and a trend graph of the negative sequence asymmetry coefficient is drawn to analyze the characteristics in the time dimension.

[0133] Specifically, the negative sequence asymmetry coefficient is the ratio of the negative sequence voltage root mean square to the positive sequence voltage root mean square.

[0134] In one embodiment, the power grid quality parameter is a voltage asymmetry index; and the quality parameter deviation value is a voltage asymmetry deviation value. Figure 8 , the steps of step S102 include:

[0135] Step S801, obtaining the negative sequence asymmetry coefficient in the sample data set.

[0136] Here, the negative sequence asymmetry coefficient root mean square represents the overall level of negative sequence asymmetry in a monitoring period. The root mean square value can smooth out short-term fluctuations and reflect the average state of negative sequence asymmetry in the entire monitoring period.

[0137] Step S802: based on the negative sequence asymmetry coefficient, determine the negative sequence asymmetry coefficient root mean square of a preset monitoring period, and set the ratio of the negative sequence asymmetry coefficient root mean square to a preset root mean square threshold as the voltage asymmetry index.

[0138] Here, the voltage asymmetry index is an important indicator to measure the symmetry of the three-phase voltage of the power grid, and is used to determine whether the power grid is in a healthy operating state.

[0139] Step S803, determining whether the negative sequence asymmetry coefficient of each first sampling period is greater than a preset coefficient threshold.

[0140] Here, if the negative sequence asymmetry coefficient is greater than the preset coefficient threshold, it is determined that the three-phase voltage is asymmetric within the sampling period and recorded as unqualified data.

[0141] If the negative sequence asymmetry coefficient is less than or equal to the preset coefficient threshold, it is determined that the three-phase voltage symmetry is qualified within the sampling period.

[0142] Step S804, if the negative-sequence asymmetry coefficient is greater than the preset coefficient threshold, determine that the three-phase voltage data of the first sampling period is unqualified; take the total number of unqualified three-phase voltage data as the number of unqualified three-phase voltage data in the preset monitoring period; the initial value of the number of unqualified three-phase voltage data is 0.

[0143] Step S805, based on the number of unqualified three-phase voltage data and the total number of the first sampling period, obtain the qualified rate of the three-phase voltage data in the preset monitoring period.

[0144] Here, the yield analysis can be combined with different time periods or different monitoring points to perform a more detailed voltage symmetry assessment.

[0145] Step S806, determining whether the pass rate of the three-phase voltage data is less than a preset second pass rate threshold.

[0146] Here, the first pass rate threshold may be preset according to actual conditions, and may be set to 95%.

[0147] Step S807, if the three-phase voltage data pass rate is less than the preset second pass rate threshold, determine whether the voltage asymmetry index is greater than 1; if the voltage asymmetry index is less than or equal to 1, determine the voltage asymmetry deviation value to be the preset deviation value; if the voltage asymmetry index is greater than 1, determine the voltage asymmetry deviation value to be the voltage asymmetry index-1.

[0148] Here, if the qualified rate of the three-phase voltage data is less than the preset second qualified rate threshold, and the voltage asymmetry index is less than or equal to 1, the voltage symmetry is determined to be qualified, and the deviation value is set to a preset value (such as 0).

[0149] If the qualified rate of the three-phase voltage data is less than the preset second qualified rate threshold, and the voltage asymmetry index is greater than 1, the voltage asymmetry deviation value is determined to be the voltage asymmetry index-1.

[0150] Step S808, if the qualified rate of the three-phase voltage data is greater than or equal to the preset second qualified rate threshold, determine whether the voltage asymmetry index is 0; if the voltage asymmetry index is 0, determine that the voltage asymmetry deviation value is a preset deviation value.

[0151] Here, if the pass rate of the three-phase voltage data is greater than or equal to the preset second pass rate threshold, and the voltage asymmetry index is 0, the deviation value is set to a preset value (such as 0).

[0152] Specifically, the voltage asymmetry index is in, For an acceptable level of asymmetry (default 2%), VNSN 10min,max VNSN in the current period 10min The maximum value (a point is generated every 10 minutes, and the maximum point is taken),

[0153] The pass rate is in, At this time, T(failed) is incremented by 1. T(totle) ​​is the total number of times in the current monitoring cycle, and T(failed) is the number of unqualified times.

[0154] The voltage asymmetry deviation is Wherein, ΔW3 is the voltage asymmetry deviation value.

[0155] For example: T total =100, T failed =10: According to ΔT<95%:ΔW3=W3-1=4-1=3.

[0156] In one embodiment, when the electric energy meter is a three-phase electric energy meter, the power data includes three-phase voltage data; the preset sampling period is a first sampling period and a second sampling period; the first sampling period is less than the second sampling period; the power quality index data includes a long-term flicker value. The steps of step S202 include:

[0157] Based on the instantaneous flicker value in the three-phase voltage data, the short-time flicker value of the first sampling period is calculated; the short-time flicker value is the root mean square of the instantaneous flicker value.

[0158] Here, the instantaneous flicker value is an electrical indicator calculated based on the visual flickering sensation caused by voltage fluctuations on lighting lamps, usually based on the rapid change characteristics of the waveform. The short-term flicker value reflects the comprehensive visual impact of voltage fluctuations over a period of time. The short-term flicker value is an important indicator that reflects the flicker situation of the power grid in a short period of time (such as 10 minutes), which facilitates the rapid assessment of the immediate impact of power grid fluctuations.

[0159] The short-time flicker value is calculated based on the instantaneous flicker value in the first sampling period.

[0160] The long-term flicker value is calculated based on multiple short-term flicker values ​​in the second sampling period, and the long-term flicker value is.

[0161] Based on the short-term flicker value corresponding to each first sampling period within the second sampling period, the long-term flicker value of the second sampling period is calculated; the calculation formula corresponding to the long-term flicker value is as follows:

[0162]

[0163] Among them, P st is the short-time flicker value, P lt is the long-term flicker value, n is the number of short-term flicker values, P st,i is the short-term flicker value corresponding to each first sampling period. If the first sampling period is 10 minutes, then P st,i There is one short-time flicker value every 10 minutes, and a total of 12 short-time values ​​make up a 2-hour cycle.

[0164] Here, the long-term flicker value is a comprehensive indicator obtained by statistically analyzing multiple short-term flicker values, and is usually used to reflect the flicker characteristics within two hours.

[0165] Specifically, the short-term flicker value is P st is the instantaneous flicker value, obtained by measuring the instantaneous voltage fluctuation, P inst It is the short-time flicker value within 10 minutes.

[0166] In one embodiment, the power grid quality parameter is the voltage flicker fluctuation rate; the quality parameter deviation value is the voltage flicker deviation value. Fig. 9 , the steps of step S102 include:

[0167] Step S901, obtaining the long-term flicker value in the sampling data set, and screening out the maximum value among the long-term flicker values ​​as the target long-term flicker value.

[0168] Here, from all the long-term flicker values ​​in the current monitoring period, the maximum value is selected as the target long-term flicker value.

[0169] The maximum long-term flicker value indicates the most serious flicker situation in the current monitoring period and is an important reference indicator for evaluating power grid quality.

[0170] Step S902: setting the ratio of the long-term flicker value to the preset allowable level threshold as the voltage flicker fluctuation rate.

[0171] Here, the voltage flicker fluctuation rate reflects the degree of deviation of the current flicker level from the allowable value, which is convenient for judging whether the power grid meets the quality requirements.

[0172] Different allowable level thresholds can be set according to different user types (such as industrial users and residential users).

[0173] Step S903, determining whether the long-term flicker value of each second sampling period is greater than a preset flicker value threshold.

[0174] Here, the preset flicker value is preset according to actual conditions.

[0175] Step S904, if the long-term flicker value is greater than the flicker value threshold, determine that the instantaneous flicker value of the second sampling period is unqualified; take the total number of unqualified instantaneous flicker values ​​as the number of unqualified instantaneous flicker values ​​of the preset monitoring period; the initial value of the number of unqualified instantaneous flicker values ​​is 0.

[0176] Step S905, based on the number of unqualified instantaneous flicker values ​​and the total number of the second sampling period, obtain the qualified rate of the instantaneous flicker value of the preset monitoring period.

[0177] Here, the pass rate reflects the overall compliance of flicker in the current monitoring period.

[0178] Step S906, determining whether the instantaneous flicker value pass rate is less than a preset third pass rate threshold.

[0179] Here, the third pass rate threshold may be preset according to actual conditions, and may be set to 95%.

[0180] Step S907: if the instantaneous flicker value qualified rate is less than the preset third qualified rate threshold, the voltage flicker deviation value is determined to be the voltage flicker fluctuation rate-1.

[0181] Here, if the instantaneous flicker value qualification rate is less than 95%, the voltage flicker deviation value is determined to be the voltage flicker fluctuation rate -1.

[0182] Step S908: If the instantaneous flicker value pass rate is greater than or equal to the preset third pass rate threshold, determine that the voltage flicker deviation value is a preset deviation value.

[0183] Here, if the instantaneous flicker value qualification rate is greater than or equal to 95%, the voltage flicker deviation value is determined to be a preset deviation value.

[0184] Specifically, the voltage flicker fluctuation rate is Among them, P ltmax is the maximum value of the long-term flicker value in the current monitoring period, P ltpermissiblelevel is the permissible level of long-term flicker (the default value is 1).

[0185] The pass rate is Among them, long-duration flicker P lt >P ltpermissiblelevel ,At this time, T(failed) is increased by 1. T(totle) ​​is the total number of times in the current monitoring cycle (for example, 84 times, sampling is performed every week for 120 minutes), and T(failed) is the number of unqualified times.

[0186] The voltage flicker deviation value is Among them, ΔW4 is the voltage flicker deviation value.

[0187] For example: st = 0.5, 0.6, ..., 0.8, a total of 12 short-time flicker values. ltmax =1.2, P ltpermissiblelevel =1: T total =84, T failed =5: According to ΔT<95%:ΔW4=W4-1=1.2-1=0.2.

[0188] Step S103, determining whether the quality parameter deviation value is a preset deviation value.

[0189] Here, the preset deviation value may be set to 0.

[0190] The deviation value of each power grid quality parameter is compared with the preset deviation value. If the deviation value is 0, it is determined that the power grid quality meets the requirements.

[0191] Step S104: if the quality parameter deviation value is not the preset deviation value, it is determined that the power grid quality is unqualified.

[0192] Here, if the deviation value is not 0, it is determined to be abnormal.

[0193] Here, the electric energy meter is provided with a display unit. When it is determined that the quality of the power grid is unqualified, the display unit of the electric energy meter can display an alarm message to prompt the user.

[0194] The electric energy meter may also be provided with an alarm unit, which may be an alarm light. When the quality of the power grid is determined to be unqualified, an alarm is triggered and the user is prompted by the alarm light.

[0195] In one embodiment, the electric energy meter is connected to the host computer of the peripheral device, and after the electric energy meter calculates the grid quality data corresponding to each preset monitoring period, the grid quality data is sent to the host computer to save the grid quality data. The host computer determines whether there is a quality problem in the current grid according to the grid quality data, and determines the cause of the problem based on the grid quality data.

[0196] A method for monitoring power grid quality provided by an embodiment of the present invention includes: obtaining power data of the power grid collected by the sampling channel of the power meter according to a preset monitoring cycle to obtain a sampling data set; at least one sampling channel is set in the power meter; based on a preset power grid quality data calculation method, each sampling data set is calculated to obtain power grid quality data corresponding to each sampling channel; the power grid quality data includes power grid quality parameters and quality parameter deviation values; judging whether the quality parameter deviation value is a preset deviation value; if the quality parameter deviation value is not a preset deviation value, determining that the power grid quality is unqualified. In this method, the power grid quality data of the application power grid quality can be obtained by calculating the real-time power data, thereby realizing accurate monitoring of the power grid quality and rapid identification of abnormalities, thereby improving the real-time nature of power quality, power supply stability and safety of power grid operation.

[0197] Embodiment 2:

[0198] Fig.10 A schematic diagram of a power grid quality monitoring system provided in an embodiment of the present invention.

[0199] Reference Fig.10 , the power grid quality monitoring system includes:

[0200] The monitoring module 1 is used to obtain the power data of the power grid collected by the sampling channel of the power meter according to a preset monitoring period to obtain a sampling data set; at least one sampling channel is set in the power meter.

[0201] The power grid quality data calculation module 2 is used to calculate each sampling data set based on a preset power grid quality data calculation method to obtain the power grid quality data corresponding to each sampling channel; the power grid quality data includes power grid quality parameters and quality parameter deviation values.

[0202] The power grid quality judgment module 3 is used to judge whether the quality parameter deviation value is a preset deviation value.

[0203] The power grid quality judgment module 3 is further used to determine that the power grid quality is unqualified if the quality parameter deviation value is not a preset deviation value.

[0204] In one embodiment, the monitoring module 1 is further used for:

[0205] According to the preset sampling period, the power data collected by each sampling channel is obtained.

[0206] Based on the preset power quality index calculation method, each power data is calculated to obtain the power quality index data corresponding to the current sampling period.

[0207] The power data of the current sampling period and its corresponding power quality indicator data are associated and saved in the sampling data set of the sampling channel.

[0208] In one embodiment, the power data includes voltage data; the preset sampling period is the first sampling period; the power quality index data includes a voltage drop ratio and a voltage rise ratio. The monitoring module 1 is also used for:

[0209] Based on the voltage data, a periodic voltage root mean square of each sampling channel in a first sampling period is calculated, and a maximum value of the periodic voltage root mean square is determined as a target periodic voltage root mean square.

[0210] Based on a preset voltage slow change index calculation formula and a target period voltage root mean square, the voltage slow change index of the current first sampling period is calculated.

[0211] Based on the voltage slow change index, the preset voltage drop threshold and the voltage rise threshold, the voltage drop ratio and the voltage rise ratio of the current first sampling period are calculated.

[0212] In one embodiment, the power grid quality parameter is a voltage slow change index; the quality parameter deviation value is a voltage slow change deviation value. The power grid quality data calculation module 2 is also used for:

[0213] The voltage drop ratio and the voltage rise ratio in the sampling data set are obtained, and the maximum value of the voltage drop ratio and the voltage rise ratio is screened out as the voltage slow change index.

[0214] It is determined whether the voltage drop ratio and / or the voltage rise ratio in each first sampling period is greater than 1.

[0215] If the voltage drop ratio and / or the voltage rise ratio is greater than 1, the voltage data of the first sampling period is determined to be unqualified; the total number of unqualified voltage data is used as the number of unqualified voltage data in the preset monitoring period; the initial value of the number of unqualified voltage slow change index is 0.

[0216] Based on the number of unqualified voltage data and the total number of the first sampling period, a qualified rate of voltage data in a preset monitoring period is obtained.

[0217] It is determined whether the voltage data pass rate is less than a preset first pass rate threshold.

[0218] If the voltage data qualification rate is greater than or equal to a preset first qualification rate threshold, the voltage slowly changing deviation value is determined to be a preset deviation value.

[0219] If the qualified rate is less than the preset first qualified rate threshold, the voltage slow change deviation value is determined to be the voltage slow change index-1.

[0220] In one embodiment, the power data includes voltage data; the preset sampling period is the first sampling period; and the power quality index data includes voltage total harmonic distortion ratio. The monitoring module 1 is also used for:

[0221] Based on the voltage data, the voltage total harmonic distortion of each sampling channel in the first sampling period is calculated, and the maximum value of the voltage total harmonic distortion is determined as the target voltage total harmonic distortion.

[0222] Based on the target voltage total harmonic distortion and a preset harmonic distortion threshold, the voltage total harmonic distortion ratio of the current first sampling period is calculated.

[0223] In one embodiment, the power grid quality parameter is a voltage distortion index; the quality parameter deviation value is a voltage distortion deviation value. The power grid quality data calculation module 2 is also used for:

[0224] The voltage total harmonic distortion ratio values ​​in the sampling data set are obtained, and the maximum value of the voltage total harmonic distortion ratio values ​​is screened out as the voltage distortion index.

[0225] Determine whether the voltage distortion index is greater than 1.

[0226] If the voltage distortion index is less than or equal to 1, the voltage distortion deviation value is determined to be a preset deviation value.

[0227] If the voltage distortion index is greater than 1, the voltage distortion deviation value is determined to be the voltage slow change index-1.

[0228] In one embodiment, when the electric energy meter is a three-phase electric energy meter, the power data includes three-phase voltage data; the preset sampling period is the first sampling period; and the power quality index data includes a negative sequence asymmetry coefficient. The monitoring module 1 is also used for:

[0229] Based on the three-phase voltage data, the negative-sequence voltage root mean square and the positive-sequence voltage root mean square in the first sampling period are calculated.

[0230] The ratio of the negative sequence voltage root mean square to the positive sequence voltage root mean square is taken as the negative sequence asymmetry coefficient.

[0231] In one embodiment, the power grid quality parameter is a voltage asymmetry index; the quality parameter deviation value is a voltage asymmetry deviation value. The power grid quality data calculation module 2 is also used to:

[0232] Get the negative sequence asymmetry coefficient in the sampled data set.

[0233] Based on the negative-sequence asymmetry coefficient, a negative-sequence asymmetry coefficient root mean square of a preset monitoring period is determined, and a ratio of the negative-sequence asymmetry coefficient root mean square to a preset root mean square threshold is set as a voltage asymmetry index.

[0234] It is determined whether the negative sequence asymmetry coefficient of each first sampling period is greater than a preset coefficient threshold.

[0235] If the negative-sequence asymmetry coefficient is greater than the preset coefficient threshold, the three-phase voltage data of the first sampling period is determined to be unqualified; the total number of unqualified three-phase voltage data is taken as the number of unqualified three-phase voltage data in the preset monitoring period; the initial value of the number of unqualified three-phase voltage data is 0.

[0236] Based on the number of unqualified three-phase voltage data and the total number of the first sampling period, the qualified rate of the three-phase voltage data in the preset monitoring period is obtained.

[0237] It is determined whether the pass rate of the three-phase voltage data is less than a preset second pass rate threshold.

[0238] If the pass rate of the three-phase voltage data is less than the preset second pass rate threshold, determine whether the voltage asymmetry index is greater than 1; if the voltage asymmetry index is less than or equal to 1, determine the voltage asymmetry deviation value to be the preset deviation value; if the voltage asymmetry index is greater than 1, determine the voltage asymmetry deviation value to be the voltage asymmetry index-1.

[0239] If the qualified rate of the three-phase voltage data is greater than or equal to the preset second qualified rate threshold, it is determined whether the voltage asymmetry index is 0; if the voltage asymmetry index is 0, the voltage asymmetry deviation value is determined to be a preset deviation value.

[0240] In one embodiment, when the electric energy meter is a three-phase electric energy meter, the power data includes three-phase voltage data; the preset sampling period is a first sampling period and a second sampling period; the first sampling period is less than the second sampling period; the power quality index data includes a long-term flicker value. The monitoring module 1 is also used for:

[0241] Based on the instantaneous flicker value in the three-phase voltage data, the short-time flicker value of the first sampling period is calculated; the short-time flicker value is the root mean square of the instantaneous flicker value.

[0242] Based on the short-term flicker value corresponding to each first sampling period within the second sampling period, the long-term flicker value of the second sampling period is calculated; the calculation formula corresponding to the long-term flicker value is as follows:

[0243]

[0244] Among them, P lt is the long-term flicker value, n is the number of short-term flicker values, P st,i It is the short-time flicker value corresponding to each first sampling period.

[0245] In one embodiment, the power grid quality parameter is the voltage flicker fluctuation rate; the quality parameter deviation value is the voltage flicker deviation value. The power grid quality data calculation module 2 is also used to:

[0246] The long-term flicker value in the sampling data set is obtained, and the maximum value among the long-term flicker values ​​is screened out as the target long-term flicker value.

[0247] The ratio of the long-term flicker value to the preset allowable level threshold is set as the voltage flicker fluctuation rate.

[0248] It is determined whether the long-term flicker value of each second sampling period is greater than a preset flicker value threshold.

[0249] If the long-term flicker value is greater than the flicker value threshold, the instantaneous flicker value of the second sampling period is determined to be unqualified; the total number of unqualified instantaneous flicker values ​​is taken as the number of unqualified instantaneous flicker values ​​of the preset monitoring period; the initial value of the number of unqualified instantaneous flicker values ​​is 0.

[0250] Based on the number of unqualified instantaneous flicker values ​​and the total number of the second sampling period, the qualified rate of the instantaneous flicker value of the preset monitoring period is obtained.

[0251] Determine whether the instantaneous flicker value pass rate is less than a preset third pass rate threshold.

[0252] If the instantaneous flicker value pass rate is less than the preset third pass rate threshold, the voltage flicker deviation value is determined to be the voltage flicker fluctuation rate-1.

[0253] If the instantaneous flicker value pass rate is greater than or equal to a preset third pass rate threshold, the voltage flicker deviation value is determined to be a preset deviation value.

[0254] An embodiment of the present invention provides a power grid quality monitoring system, in which power grid quality data of the application power grid can be calculated through real-time power data, thereby achieving accurate monitoring of the power grid quality and rapid identification of anomalies, thereby improving the real-time nature of power quality, power supply stability and safety of power grid operation.

[0255] The computer program product provided in the embodiment of the present invention includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the method described in the previous method embodiment. The specific implementation can be found in the method embodiment and will not be repeated here.

[0256] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0257] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0258] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0259] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0260] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for monitoring power grid quality, characterized in that: include: According to a preset monitoring cycle, power data of the power grid collected by a sampling channel of the power meter is obtained to obtain a sampling data set; the power meter is provided with at least one sampling channel; Based on a preset power grid quality data calculation method, each of the sampled data sets is calculated to obtain power grid quality data corresponding to each of the sampling channels; the power grid quality data includes power grid quality parameters and quality parameter deviation values; Determining whether the quality parameter deviation value is a preset deviation value; If the quality parameter deviation value is not the preset deviation value, it is determined that the power grid quality is unqualified.

2. The method for monitoring power grid quality according to claim 1, characterized in that: The step of obtaining the power data of the power grid collected by the sampling channel of the electric energy meter according to the preset monitoring cycle to obtain the sampling data set includes: According to a preset sampling period, acquiring the power data collected by each sampling channel; Based on a preset power quality index calculation method, each of the power data is calculated to obtain power quality index data corresponding to the current sampling period; The power data of the current sampling period and the corresponding power quality indicator data are associated and saved in the sampling data set of the sampling channel.

3. The method for monitoring power grid quality according to claim 2, characterized in that: The power data includes voltage data; the preset sampling period is the first sampling period; the power quality index data includes a voltage drop ratio and a voltage rise ratio; The method of calculating each of the power data based on the power quality index calculation method to obtain the power quality index data corresponding to each of the sampling channels includes: Based on the voltage data, a periodic voltage root mean square of each of the sampling channels in the first sampling period is calculated, and a maximum value of the periodic voltage root mean square is determined as a target periodic voltage root mean square; Based on a preset voltage slow change index calculation formula and the target period voltage root mean square, calculate the voltage slow change index of the current first sampling period; The voltage drop ratio and the voltage rise ratio of the current first sampling period are calculated based on the voltage slow change index, a preset voltage drop threshold and a preset voltage rise threshold.

4. The method for monitoring power grid quality according to claim 3, characterized in that: The power grid quality parameter is a voltage slow change index; the quality parameter deviation value is a voltage slow change deviation value; The step of calculating each of the sampled data sets based on a preset power grid quality data calculation method to obtain the power grid quality data corresponding to each of the sampling channels comprises: Acquire the voltage drop ratio and the voltage rise ratio in the sampled data set, and select the maximum value of the voltage drop ratio and the voltage rise ratio as the voltage slow change index; Determine whether the voltage drop ratio and / or the voltage rise ratio of each of the first sampling periods is greater than 1; If the voltage drop ratio and / or the voltage rise ratio is greater than 1, the voltage data of the first sampling period is determined to be unqualified; the total number of unqualified voltage data is used as the number of unqualified voltage data of the preset monitoring period; the initial value of the number of unqualified voltage slow change index is 0; Based on the number of unqualified voltage data and the total number of first sampling cycles, obtaining a qualified rate of voltage data in the preset monitoring cycle; Determining whether the voltage data pass rate is less than a preset first pass rate threshold; If the voltage data pass rate is greater than or equal to the preset first pass rate threshold, determining the voltage slowly changing deviation value to be the preset deviation value; If the qualified rate is less than the preset first qualified rate threshold, the voltage slow change deviation value is determined to be the voltage slow change index-1.

5. The method for monitoring power grid quality according to claim 2, characterized in that: The power data includes voltage data; the preset sampling period is a first sampling period; the power quality index data includes a voltage total harmonic distortion ratio; The method of calculating each of the power data based on the power quality index calculation method to obtain the power quality index corresponding to each of the sampling channels includes: Based on the voltage data, a voltage total harmonic distortion of each of the sampling channels within the first sampling period is calculated, and a maximum value of the voltage total harmonic distortion is determined as a target voltage total harmonic distortion; The voltage total harmonic distortion ratio of the current first sampling period is calculated based on the target voltage total harmonic distortion and a preset harmonic distortion threshold.

6. The method for monitoring power grid quality according to claim 5, characterized in that: The power grid quality parameter is a voltage distortion index; the quality parameter deviation value is a voltage distortion deviation value; The step of calculating each of the sampled data sets based on a preset power grid quality data calculation method to obtain the power grid quality data corresponding to each of the sampling channels comprises: Acquire the voltage total harmonic distortion ratio in the sampling data set, and filter out the maximum value of the voltage total harmonic distortion ratio as the voltage distortion index; Determining whether the voltage distortion index is greater than 1; If the voltage distortion index is less than or equal to 1, determining the voltage distortion deviation value to be the preset deviation value; If the voltage distortion index is greater than 1, the voltage distortion deviation value is determined to be the voltage slow change index-1.

7. The method for monitoring power grid quality according to claim 2, characterized in that: When the electric energy meter is a three-phase electric energy meter, the electric power data includes three-phase voltage data; the preset sampling period is the first sampling period; the electric energy quality index data includes a negative sequence asymmetry coefficient; The method of calculating each of the power data based on the power quality index calculation method to obtain the power quality index corresponding to each of the sampling channels includes: Based on the three-phase voltage data, a negative-sequence voltage root mean square and a positive-sequence voltage root mean square within the first sampling period are calculated; The ratio of the negative sequence voltage root mean square to the positive sequence voltage root mean square is used as a negative sequence asymmetry coefficient.

8. The method for monitoring power grid quality according to claim 7, characterized in that: The power grid quality parameter is a voltage asymmetry index; the quality parameter deviation value is a voltage asymmetry deviation value; The step of calculating each of the sampled data sets based on a preset power grid quality data calculation method to obtain the power grid quality data corresponding to each of the sampling channels comprises: Obtaining the negative sequence asymmetry coefficient in the sample data set; Based on the negative-sequence asymmetry coefficient, determining a negative-sequence asymmetry coefficient root mean square of the preset monitoring period, and setting a ratio of the negative-sequence asymmetry coefficient root mean square to a preset root mean square threshold as the voltage asymmetry index; Determining whether the negative-sequence asymmetry coefficient of each of the first sampling periods is greater than a preset coefficient threshold; If the negative sequence asymmetry coefficient is greater than the preset coefficient threshold, the three-phase voltage data of the first sampling period is determined to be unqualified; the total number of unqualified three-phase voltage data is taken as the number of unqualified three-phase voltage data of the preset monitoring period; the initial value of the number of unqualified three-phase voltage data is 0; Based on the number of unqualified three-phase voltage data and the total number of the first sampling period, obtaining the qualified rate of the three-phase voltage data in the preset monitoring period; Determining whether the pass rate of the three-phase voltage data is less than a preset second pass rate threshold; If the qualified rate of the three-phase voltage data is less than the preset second qualified rate threshold, determine whether the voltage asymmetry index is greater than 1; if the voltage asymmetry index is less than or equal to 1, determine that the voltage asymmetry deviation value is the preset deviation value; if the voltage asymmetry index is greater than 1, determine that the voltage asymmetry deviation value is the voltage asymmetry index-1; If the qualified rate of the three-phase voltage data is greater than or equal to the preset second qualified rate threshold, determine whether the voltage asymmetry index is 0; if the voltage asymmetry index is 0, determine that the voltage asymmetry deviation value is the preset deviation value.

9. The method for monitoring power grid quality according to claim 2, characterized in that: When the electric energy meter is a three-phase electric energy meter, the power data includes three-phase voltage data; the preset sampling period is a first sampling period and a second sampling period; the first sampling period is less than the second sampling period; the power quality index data includes a long-term flicker value; The method of calculating each of the power data based on the power quality index calculation method to obtain the power quality index corresponding to each of the sampling channels includes: Based on the instantaneous flicker value in the three-phase voltage data, a short-time flicker value of the first sampling period is calculated; the short-time flicker value is the root mean square of the instantaneous flicker value; Based on the short-term flicker value corresponding to each of the first sampling periods within the second sampling period, the long-term flicker value of the second sampling period is calculated; the calculation formula corresponding to the long-term flicker value is as follows: Among them, P lt is the long-term flicker value, n is the number of short-term flicker values, P st,i The short-time flicker value corresponding to each of the first sampling periods.

10. The method for monitoring power grid quality according to claim 9, characterized in that: The power grid quality parameter is the voltage flicker fluctuation rate; the quality parameter deviation value is the voltage flicker deviation value; The step of calculating each of the sampled data sets based on a preset power grid quality data calculation method to obtain the power grid quality data corresponding to each of the sampling channels comprises: Acquire the long-term flicker value in the sampling data set, and filter out the maximum value among the long-term flicker values ​​as the target long-term flicker value; The ratio of the long-term flicker value to a preset allowable level threshold is set as the voltage flicker fluctuation rate; Determine whether the long-term flicker value of each of the second sampling periods is greater than a preset flicker value threshold; If the long-term flicker value is greater than the flicker value threshold, determine that the instantaneous flicker value of the second sampling period is unqualified; take the total number of unqualified instantaneous flicker values ​​as the number of unqualified instantaneous flicker values ​​of the preset monitoring period; the initial value of the number of unqualified instantaneous flicker values ​​is 0; Based on the number of unqualified instantaneous flicker values ​​and the total number of the second sampling period, obtaining the qualified rate of the instantaneous flicker value of the preset monitoring period; Determining whether the instantaneous flicker value pass rate is less than a preset third pass rate threshold; If the instantaneous flicker value qualified rate is less than the preset third qualified rate threshold, determining the voltage flicker deviation value to be the voltage flicker fluctuation rate-1; If the instantaneous flicker value pass rate is greater than or equal to the preset third pass rate threshold, the voltage flicker deviation value is determined to be the preset deviation value.

11. A power grid quality monitoring system, characterized in that: include: A monitoring module, used to obtain the power data of the power grid collected by the sampling channel of the power meter according to a preset monitoring period to obtain a sampling data set; the power meter is provided with at least one sampling channel; A power grid quality data calculation module, used to calculate each of the sampled data sets based on a preset power grid quality data calculation method to obtain power grid quality data corresponding to each of the sampling channels; the power grid quality data includes power grid quality parameters and quality parameter deviation values; A power grid quality judgment module, used to judge whether the quality parameter deviation value is a preset deviation value; The power grid quality judgment module is further used to determine that the power grid quality is unqualified if the quality parameter deviation value is not the preset deviation value.

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