A method and system for monitoring operating parameters of low-voltage distribution lines

Abstract

The present invention relates to the technical field of power distribution network, and discloses a method and system for monitoring the operating parameters of a low-voltage distribution line. The present invention connects a measuring device with a plurality of disturbance loads with known impedance parameters installed inside the low-voltage side of the low-voltage distribution line; by repeatedly adjusting the switching state of various disturbance loads in the measuring device, the voltage and current values ​​of each node inside the device under different disturbance loads are measured to obtain a measurement data group under different disturbance loads; the external impedance of the measuring device is calculated according to the measurement data group; the data is associated with the corresponding measurement time, and a curve diagram of the relationship between the measurement data group and time and a curve diagram of the relationship between impedance and time are drawn. The present invention realizes the adjustment of load changes on the line by connecting to the measuring device, and can monitor the voltage, current and impedance parameters under different loads without the cooperation of the user, and the convenience is effectively improved. The obtained monitoring data and the time factor are graphically represented to improve the monitoring quality.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution networks, and in particular to a method and system for monitoring operating parameters of a low-voltage power distribution line. Background Art

[0002] With the development of smart distribution networks, fault identification, risk prediction, operation and maintenance analysis, etc. have put forward higher requirements on the convenience and quality of low-voltage distribution line operating parameter monitoring.

[0003] Changes in voltage, current, and impedance parameters on low-voltage distribution lines are associated with changes in user power loads on the lines. Power load changes can be divided into continuous and step-by-step types, and the corresponding time intervals are continuous small load fluctuation time intervals and step-by-step load increase and decrease time intervals. User power loads are generally switched on by each individual through the equipment's switch. Due to the limitations of the equipment's capacity and switching control equipment, small loads can fluctuate continuously. Larger loads are mainly switched on and off by switches, resulting in a direct jump or drop, and then reaching a new load, where they will fluctuate horizontally and run for a long time. It can be seen that the duration of continuous fluctuations of small loads in low-voltage distribution networks is much longer than the duration of sudden increases and decreases and step-by-step changes.

[0004] Because power grid companies cannot control the switching on and off of user equipment, monitoring the operating parameters of low-voltage distribution lines requires user cooperation or online collection of switching data from each load node, which makes monitoring inconvenient. Furthermore, existing low-voltage distribution line operating parameter monitoring methods only record parameter monitoring values ​​and ignore the measurement time data. As a result, the resulting operating parameter monitoring data is not suitable for some low-voltage distribution line analysis scenarios, resulting in low monitoring quality. Summary of the Invention

[0005] The present invention provides a method and system for monitoring the operating parameters of a low-voltage distribution line, which solves the technical problem of how to improve the convenience and quality of monitoring the operating parameters of a low-voltage distribution line.

[0006] A first aspect of the present invention provides a method for monitoring operating parameters of a low-voltage distribution line, the method comprising:

[0007] A measuring device for disturbance loads with various known impedance parameters is installed on the low-voltage side of the low-voltage distribution line;

[0008] By adjusting the switching states of various disturbance loads in the measuring device multiple times, measuring the voltage and current values ​​of each node in the measuring device under different disturbance loads, and obtaining measurement data groups under different disturbance loads;

[0009] calculating an external impedance of the measuring device based on the measurement data set;

[0010] The measurement data group is associated with the corresponding measurement time, and a measurement data group-time relationship curve is drawn. The calculated external impedance of the measurement device is associated with the corresponding measurement time, and a impedance-time relationship curve is drawn.

[0011] According to an achievable method of the first aspect of the present invention, the method of repeatedly adjusting the switching states of various disturbance loads in the measuring device and measuring the voltage and current values ​​of each node inside the measuring device under different disturbance loads to obtain a measurement data group under different disturbance loads includes:

[0012] Measuring the voltage and current values ​​of each node in the measuring device when all disturbance loads are not applied, to obtain a first measurement data group;

[0013] After obtaining the first measurement data set, actively stimulating at least one disturbance load through the measurement device, measuring the voltage and current values ​​of each node inside the measurement device under the current disturbance load, and obtaining a second measurement data set;

[0014] After obtaining the second measurement data set, the measurement device actively removes or increases the disturbance load, measures the voltage and current values ​​of each node inside the measurement device under the current disturbance load, and obtains a third measurement data set;

[0015] After obtaining the third measurement data set, the measurement device actively removes or increases the disturbance load, measures the voltage and current values ​​of each node inside the measurement device under the current disturbance load, and obtains a fourth measurement data set;

[0016] Calculating the external impedance of the measuring device according to the measurement data group includes:

[0017] Comparing the difference between the first measurement data group and the fourth measurement data group, and determining whether the measurement time corresponding to each measurement data group is within the continuous small and micro load fluctuation time interval according to the obtained difference comparison result, to obtain a corresponding determination result;

[0018] If the determination result is yes, it is determined that the external impedances of the measurement devices corresponding to the various measurement data groups are substantially equal, and any one measurement data group is selected from the first measurement data group, the second measurement data group, the third measurement data group, and the fourth measurement data group to calculate the external impedance of the measurement device.

[0019] According to an achievable manner of the first aspect of the present invention, the calculating the external impedance of the measuring device according to the measurement data set further includes:

[0020] If the determination result is no, it is determined that the external impedances of the measurement devices corresponding to the measurement data groups are not equal, and the external impedances of the measurement devices corresponding to the first measurement data group, the second measurement data group, the third measurement data group, and the fourth measurement data group are calculated respectively.

[0021] According to an implementation of the first aspect of the present invention, comparing the difference between the first measurement data group and the fourth measurement data group, and determining whether the measurement time corresponding to each measurement data group is within the continuous small and micro load fluctuation time interval based on the obtained difference comparison result, includes:

[0022] calculating a current difference value at each node between the first measurement data group and the fourth measurement data group, and determining a maximum current difference value therefrom;

[0023] calculating voltage difference values ​​at each node between the first measurement data group and the fourth measurement data group, and determining a maximum voltage difference value therefrom;

[0024] If the maximum current difference value is smaller than the first difference value threshold, and the maximum voltage difference value is smaller than the second difference value threshold, it is determined that the measurement time corresponding to each measurement data group is within the continuous small load fluctuation time interval.

[0025] According to one implementation of the first aspect of the present invention, the method further includes:

[0026] Providing a neutral wire terminal and a ground wire terminal for the measuring device so that the measuring device has a fault variable simulation function;

[0027] By adjusting the switching states of various disturbance loads in the measuring device multiple times, measuring the current and voltage components generated by different disturbance loads connected to the neutral line, and measuring the current and voltage components generated by different disturbance loads connected to the ground line, a measurement data set corresponding to different disturbance loads is obtained;

[0028] The measurement data set is associated with the corresponding measurement time, and a curve diagram of the relationship between the measurement data set and time is drawn.

[0029] A second aspect of the present invention provides a low-voltage distribution line operating parameter monitoring system, the system comprising:

[0030] A measuring device is connected to the low-voltage side of a low-voltage distribution line, wherein a plurality of disturbance loads with known impedance parameters are installed inside the measuring device; the measuring device includes a first measurement control module; the first measurement control module is used to actively adjust the switching state of various internal disturbance loads, measure the voltage and current values ​​of each node inside the measuring device under different disturbance loads, and obtain measurement data sets under different disturbance loads;

[0031] The monitoring platform includes a calculation module and a drawing module; the calculation module is used to calculate the external impedance of the measuring device based on the measurement data group; the drawing module is used to associate the measurement data group with the corresponding measurement time, draw a curve chart of the relationship between the measurement data group and time, associate the calculated external impedance of the measuring device with the corresponding measurement time, and draw a curve chart of the relationship between impedance and time.

[0032] According to an implementation of the second aspect of the present invention, the first measurement control module includes:

[0033] The first measuring unit is used to measure the voltage and current values ​​of each internal node when various disturbance loads are not put into use, so as to obtain a first measurement data group;

[0034] a second measurement unit, configured to, after obtaining the first measurement data group, actively stimulate at least one disturbance load, measure the voltage and current values ​​of each node inside the measurement device under the current disturbance load, and obtain a second measurement data group;

[0035] a third measuring unit, configured to, after obtaining the second measurement data group, actively remove or increase a disturbance load, measure voltage and current values ​​of each node inside the measurement device under the current disturbance load, and obtain a third measurement data group;

[0036] a fourth measurement unit, configured to, after obtaining the third measurement data group, actively remove or increase a disturbance load, measure voltage and current values ​​of each node within the measurement device under the current disturbance load, and obtain a fourth measurement data group;

[0037] The calculation module includes:

[0038] a comparison and determination unit, configured to compare the difference between the first measurement data group and the fourth measurement data group, and determine whether the measurement time corresponding to each measurement data group is within a continuous small and micro load fluctuation time interval based on the obtained difference comparison result, thereby obtaining a corresponding determination result;

[0039] a first calculation unit, configured to, if the determination result is yes, determine that the external impedances of the measurement devices corresponding to the various measurement data groups are substantially equal, and select any one measurement data group from the first measurement data group, the second measurement data group, the third measurement data group, and the fourth measurement data group to calculate the external impedance of the measurement device.

[0040] According to an implementation of the second aspect of the present invention, the calculation module further includes:

[0041] The second calculation unit is configured to, if the determination result is negative, determine that the external impedances of the measurement devices corresponding to the measurement data groups are not equal, and respectively calculate the external impedances of the measurement devices corresponding to the first measurement data group, the second measurement data group, the third measurement data group, and the fourth measurement data group.

[0042] According to an achievable manner of the second aspect of the present invention, the comparison and determination unit includes:

[0043] a first sub-calculation unit, configured to calculate a current difference value at each node between the first measurement data group and the fourth measurement data group, and determine a maximum current difference value therefrom;

[0044] a second sub-calculation unit, configured to calculate voltage difference values ​​at each node between the first measurement data group and the fourth measurement data group, and determine a maximum voltage difference value therefrom;

[0045] The determination subunit is configured to determine that the measurement time corresponding to each measurement data group is within a continuous small load fluctuation time interval if the maximum current difference value is less than a first difference value threshold and the maximum voltage difference value is less than a second difference value threshold.

[0046] According to an achievable manner of the second aspect of the present invention, the measuring device is provided with a neutral wire terminal and a ground wire terminal;

[0047] The measuring device further includes a second measurement control module; the second measurement control module is used to measure the current and voltage components generated by different disturbance loads being connected to the neutral line, and the current and voltage components generated by different disturbance loads being connected to the ground line, by adjusting the switching states of various internal disturbance loads multiple times, to obtain measurement data sets corresponding to different disturbance loads;

[0048] The drawing module is further configured to associate the measurement data set with the corresponding measurement time, and draw a curve diagram of the relationship between the measurement data set and time.

[0049] It can be seen from the above technical solutions that the present invention has the following advantages:

[0050] The present invention connects a measuring device with a plurality of disturbance loads with known impedance parameters installed inside to the low-voltage side of a low-voltage distribution line; by repeatedly adjusting the switching states of various disturbance loads in the measuring device, the voltage and current values ​​of each node inside the measuring device under different disturbance loads are measured to obtain measurement data groups under different disturbance loads; the external impedance of the measuring device is calculated based on the measurement data group; the measurement data group is associated with the corresponding measurement time, and a measurement data group and time relationship curve is drawn; the calculated external impedance of the measuring device is associated with the corresponding measurement time, and an impedance and time relationship curve is drawn; the present invention installs the measuring device on the line and realizes the regulation of load changes on the line by adjusting the switching states of various disturbance loads in the measuring device. Without the cooperation of the user, the voltage, current and impedance parameters under different loads can be monitored, and the convenience is effectively improved. The obtained monitoring data and the time factor are graphically represented as a curve, thereby improving the monitoring quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0052] Figure 1 A flowchart of a method for monitoring operating parameters of a low-voltage distribution line provided in an optional embodiment of the present invention;

[0053] Figure 2 A simplified circuit diagram of a low-voltage distribution line connected to a measuring device according to an optional embodiment of the present invention;

[0054] Figure 3 A flowchart of a method for monitoring operating parameters of a low-voltage distribution line provided in another optional embodiment of the present invention;

[0055] Figure 4 A structural connection block diagram of a low-voltage distribution line operating parameter monitoring system provided by an optional embodiment of the present invention;

[0056] Figure 5 This is a structural connection block diagram of a low-voltage distribution line operating parameter monitoring system provided in another optional embodiment of the present invention.

[0057] Reference numerals:

[0058] 1- measuring device; 2- monitoring platform; 11- first measurement control module; 12- second measurement control module; 21- calculation module; 22- drawing module. DETAILED DESCRIPTION

[0059] The embodiments of the present invention provide a method and system for monitoring operating parameters of a low-voltage distribution line, which are used to solve the technical problem of how to improve the convenience and quality of monitoring operating parameters of a low-voltage distribution line.

[0060] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only 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 making creative work are within the scope of protection of the present invention.

[0061] The present invention provides a method for monitoring operating parameters of a low-voltage power distribution line.

[0062] See also Figure 1 , Figure 1 A flow chart of a method for monitoring operating parameters of a low-voltage distribution line provided by an embodiment of the present invention is shown.

[0063] An embodiment of the present invention provides a method for monitoring operating parameters of a low-voltage distribution line, comprising steps S1-S4.

[0064] Step S1: Connect a measuring device 1 with a plurality of disturbance loads with known impedance parameters installed therein to the low-voltage side of a low-voltage distribution line.

[0065] The current low-voltage distribution network can be simplified into a network consisting of distribution transformer equipment (power supply and power supply internal resistance), lines, loads, etc. When the system capacity is much larger than the load, it can be simplified into an equivalent circuit consisting of power supply, resistance, reactance, capacitance, etc. The present application does not perform measurements in the original low-voltage distribution network, but connects to a measuring device 1 that has a variety of disturbance loads with known impedance parameters installed inside. By actively exciting, increasing or cutting off the disturbance load inside the measuring device 1, the load in the low-voltage distribution line changes, and then the relevant operating parameters are measured. The simplified circuit schematic diagram after the low-voltage side of the low-voltage distribution line is connected to the measuring device 1 is as follows: Figure 2 shown.

[0066] Among them, the known impedance parameter can be the impedance value of loads such as resistance, capacitance, and reactance. The disturbance load of the known impedance parameter refers to the impedance value of loads such as resistance, capacitance, and reactance installed inside the measuring device 1, and the impedance value can include R resistance and X reactance. In reality, when there is no load connected to the low-voltage side of the distribution transformer, the external impedance value of the measuring device 1 is the sum of the transformer internal resistance and the line impedance value. Due to the maximum load limit that the distribution line can withstand, the input load should not damage the original low-voltage distribution line and the equipment in the low-voltage system, such as the load causing the line to be close to short-circuit, causing the switch protection to trip, etc. The upper and lower limits of the disturbance load in the measuring device 1 can be set accordingly.

[0067] Step S2 , by adjusting the switching states of various disturbance loads in the measuring device 1 multiple times, measuring the voltage and current values ​​of various nodes in the measuring device 1 under different disturbance loads, and obtaining measurement data groups under different disturbance loads.

[0068] As a feasible method, the measuring device 1 can have the function of autonomously adjusting the switching status of various internal disturbance loads, so as to realize the active excitation, increase and removal of the disturbance load, such as actively increasing one or more known disturbance loads among pure resistive loads, pure inductive loads and pure capacitive loads, and connecting different combinations of known disturbance loads to the low-voltage distribution line.

[0069] Step S3: calculating the external impedance of the measuring device 1 according to the measurement data set.

[0070] In one possible implementation, when executing step S2, specifically:

[0071] Measuring the voltage and current values ​​of each node in the measuring device 1 when all disturbance loads are not applied, to obtain a first measurement data group;

[0072] After obtaining the first measurement data set, actively stimulating at least one disturbance load through the measurement device 1, measuring the voltage and current values ​​of each node inside the measurement device 1 under the current disturbance load, and obtaining a second measurement data set;

[0073] After obtaining the second measurement data set, the measurement device 1 actively removes or increases the disturbance load, measures the voltage and current values ​​of each node inside the measurement device 1 under the current disturbance load, and obtains a third measurement data set;

[0074] After obtaining the third measurement data set, the measurement device 1 actively removes or increases the disturbance load, measures the voltage and current values ​​of each node inside the measurement device 1 under the current disturbance load, and obtains a fourth measurement data set.

[0075] According to the characteristic that the duration of continuous fluctuation of small and micro loads in the low-voltage distribution network is much longer than the duration of sudden increase and decrease step-by-step changes, it can be considered that there is a relatively stable external impedance of the measuring device 1 during the load stabilization period. Therefore, when executing step S3, the differences between the various measurement data groups can be further compared. If the differences are small, it indicates that the measurement time points of the corresponding measurement data groups are simultaneously within the time interval when the low-voltage power grid has only continuous small and micro load fluctuations. In the simplified circuit model, it can be considered that the parameters such as the impedance value of the external circuit of the measuring device 1 are basically equal for each measurement data group. If the differences are large, it indicates that the measurement time points of the corresponding measurement data groups are simultaneously within the time interval when the low-voltage power grid has step-by-step increases and decreases. In the simplified circuit model, it can be considered that the parameters such as the impedance value of the external circuit of the measuring device 1 are not equal for each measurement data group.

[0076] As an achievable method, when executing step S3, a determination is made as to whether the measurement time corresponding to each measurement data group falls within the continuous small load fluctuation time interval by comparing the difference between the first measurement data group and the fourth measurement data group, thereby obtaining a corresponding determination result. If the determination result is yes, it is determined that the external impedance of measurement device 1 corresponding to each measurement data group is substantially equal, and any one measurement data group is selected from the first measurement data group, the second measurement data group, the third measurement data group, and the fourth measurement data group to calculate the external impedance of measurement device 1.

[0077] As a specific implementation manner, comparing the difference between the first measurement data group and the fourth measurement data group, and determining whether the measurement time corresponding to each measurement data group is within the continuous small and micro load fluctuation time interval based on the obtained difference comparison result, includes:

[0078] calculating a current difference value at each node between the first measurement data group and the fourth measurement data group, and determining a maximum current difference value therefrom;

[0079] calculating voltage difference values ​​at each node between the first measurement data group and the fourth measurement data group, and determining a maximum voltage difference value therefrom;

[0080] If the maximum current difference value is smaller than the first difference value threshold, and the maximum voltage difference value is smaller than the second difference value threshold, it is determined that the measurement time corresponding to each measurement data group is within the continuous small load fluctuation time interval.

[0081] In another embodiment, comparing the difference between the first measurement data group and the fourth measurement data group, and determining whether the measurement time corresponding to each measurement data group is within the continuous small load fluctuation time interval based on the obtained difference comparison result, includes:

[0082] Calculating a current difference value at each node between the first measurement data group and the fourth measurement data group, and calculating an average current difference value based on each current difference value;

[0083] Calculating a voltage difference value at each node between the first measurement data group and the fourth measurement data group, and calculating an average voltage difference value based on each voltage difference value;

[0084] If the average current difference value is smaller than the first difference value threshold, and the average voltage difference value is smaller than the second difference value threshold, it is determined that the measurement time corresponding to each measurement data group is within the continuous small load fluctuation time interval.

[0085] As another possible implementation, when executing step S3, the external impedance of the measuring device 1 can be calculated for each of the first and fourth measurement data groups, and the difference between the external impedances of the measuring device 1 can be compared. If the difference between the external impedances of the measuring device 1 for the two groups is less than a preset impedance difference threshold, it can be determined that the measurement times corresponding to each measurement data group fall within a time interval of continuous small and micro load fluctuations, and the external impedances of the measuring device 1 corresponding to each measurement data group are determined to be substantially equal, thereby eliminating the need to calculate the external impedances of the measuring device 1 for other measurement data groups. If the difference between the external impedances of the measuring device 1 for the two groups is not less than the preset impedance difference threshold, it can be determined that the measurement times corresponding to each measurement data group fall within a time interval of stepwise increases and decreases in the low-voltage power grid, and the external impedances of the measuring device 1 corresponding to each measurement data group are determined to be unequal, thereby eliminating the need to calculate the external impedances of the measuring device 1 for the remaining measurement data groups.

[0086] It should be noted that in the above-mentioned embodiment of the present invention, only the fourth measurement data set is measured. In other embodiments, after obtaining the fourth measurement data set, the measurement device 1 can actively remove or increase the disturbance load, measure the voltage and current values ​​of each node inside the measurement device 1 under the current disturbance load, and obtain the fifth measurement data set. In the same manner, the sixth measurement data set, the seventh measurement data set, and so on can be obtained. When comparing the differences between the measurement data sets, the difference between the first measurement data set and the last measurement data set can be measured, and then the subsequent judgment and impedance calculation steps can be performed.

[0087] When calculating the impedance parameters, the external impedance of the measuring device 1 is calculated based on the current and voltage values ​​generated by the internal load changes of the measuring device 1 and the known internal load impedance value. According to the Thevenin theorem, also known as the equivalent voltage source law, under a single frequency, the external circuits and transformers of the measuring device 1 can be regarded as a combination of a voltage source and an impedance. In the time interval of continuous small load fluctuations, the voltage source and the external impedance of the measuring device 1 can be considered to be relatively stable values. When a group of disturbance loads are actively stimulated and put into the loop inside the measuring device 1, the loop voltage is distributed according to the impedance, forming equation 1. When the second group of disturbance loads is put into the loop, equation 2 is formed. When the third group of disturbance loads is put into the loop, equation 3 is formed. In this way, a combination of equations can be obtained. By measuring the current and voltage component values ​​and the known disturbance impedance value at multiple different time points and different disturbances, the unknown number in the equation, i.e., the external impedance of the measuring device 1, can be solved.

[0088] It should be noted that the calculation process of the external impedance of the measuring device 1 may also refer to other existing methods, which is not limited in this embodiment.

[0089] Step S4, associating the measurement data group with the corresponding measurement time, drawing a measurement data group vs. time relationship graph, associating the calculated external impedance of the measurement device 1 with the corresponding measurement time, and drawing an impedance vs. time relationship graph.

[0090] See also Figure 3 , Figure 3 A flowchart of a method for monitoring operating parameters of a low-voltage distribution line provided by another optional embodiment of the present invention is shown. Figure 1 In addition to steps S1-S4 shown, the following steps are also included:

[0091] Step S5, setting a neutral wire terminal and a ground wire terminal for the measuring device 1 so that the measuring device 1 has a fault variable simulation function;

[0092] Step S6, by repeatedly adjusting the switching states of various disturbance loads in the measuring device 1, measuring the current and voltage components generated by different disturbance loads connected to the neutral line, and measuring the current and voltage components generated by different disturbance loads connected to the ground line, to obtain measurement data sets corresponding to different disturbance loads;

[0093] Step S7: Associating the measurement data set with the corresponding measurement time, and drawing a curve diagram of the relationship between the measurement data set and time.

[0094] In the embodiment of the present invention, the current and voltage components generated by the disturbance load being connected to the neutral wire are measured, and the current and voltage components generated by the disturbance load being connected to the ground wire are measured, so that the measuring device 1 has various operating modes consisting of load, neutral wire and ground wire elements. Therefore, the operation of the low-voltage distribution network with disturbance loads and simulated faults can be simulated, and the operation data of the low-voltage distribution network when the disturbance loads and simulated faults exist can be collected.

[0095] The present invention also provides a low-voltage distribution line operating parameter monitoring system.

[0096] See also Figure 4 , Figure 4 The figure shows a structural connection block diagram of a low-voltage distribution line operating parameter monitoring system provided by an embodiment of the present invention.

[0097] An embodiment of the present invention provides a low-voltage distribution line operating parameter monitoring system, comprising:

[0098] A measuring device 1 is connected to the low-voltage side of a low-voltage distribution line, and is internally installed with a plurality of disturbance loads with known impedance parameters; the measuring device 1 includes a first measurement control module 11; the first measurement control module 11 is used to actively adjust the switching state of various internal disturbance loads, measure the voltage and current values ​​of each node within the measuring device 1 under different disturbance loads, and obtain measurement data sets under different disturbance loads;

[0099] The monitoring platform 2 includes a calculation module 21 and a drawing module 22; the calculation module 21 is used to calculate the external impedance of the measuring device 1 based on the measurement data group; the drawing module 22 is used to associate the measurement data group with the corresponding measurement time, draw a curve chart of the relationship between the measurement data group and time, associate the calculated external impedance of the measuring device 1 with the corresponding measurement time, and draw a curve chart of the relationship between impedance and time.

[0100] In one achievable manner, the first measurement control module 11 includes:

[0101] The first measuring unit is used to measure the voltage and current values ​​of each internal node when various disturbance loads are not put into use, so as to obtain a first measurement data group;

[0102] a second measuring unit configured to, after obtaining the first measurement data group, actively stimulate at least one disturbance load, measure the voltage and current values ​​of each node inside the measurement device 1 under the current disturbance load, and obtain a second measurement data group;

[0103] a third measuring unit, configured to, after obtaining the second measurement data group, actively remove or increase the disturbance load, measure the voltage and current values ​​of each node inside the measurement device 1 under the current disturbance load, and obtain a third measurement data group;

[0104] a fourth measuring unit, configured to, after obtaining the third measurement data group, actively remove or increase a disturbance load, measure the voltage and current values ​​of each node inside the measurement device 1 under the current disturbance load, and obtain a fourth measurement data group;

[0105] The calculation module 21 includes:

[0106] a comparison and determination unit, configured to compare the difference between the first measurement data group and the fourth measurement data group, and determine whether the measurement time corresponding to each measurement data group is within a continuous small and micro load fluctuation time interval based on the obtained difference comparison result, thereby obtaining a corresponding determination result;

[0107] a first calculation unit, configured to, if the determination result is yes, determine that the external impedances of the measuring device 1 corresponding to each measurement data group are substantially equal, and select any one measurement data group from the first measurement data group, the second measurement data group, the third measurement data group, and the fourth measurement data group to calculate the external impedance of the measuring device 1.

[0108] In one possible implementation, the calculation module 21 further includes:

[0109] The second calculation unit is configured to, if the determination result is negative, determine that the external impedances of the measurement device 1 corresponding to each measurement data group are not equal, and calculate the external impedances of the measurement device 1 corresponding to the first measurement data group, the second measurement data group, the third measurement data group, and the fourth measurement data group, respectively.

[0110] In one possible implementation, the comparison and determination unit includes:

[0111] a first sub-calculation unit, configured to calculate a current difference value at each node between the first measurement data group and the fourth measurement data group, and determine a maximum current difference value therefrom;

[0112] a second sub-calculation unit, configured to calculate voltage difference values ​​at each node between the first measurement data group and the fourth measurement data group, and determine a maximum voltage difference value therefrom;

[0113] The determination subunit is configured to determine that the measurement time corresponding to each measurement data group is within a continuous small load fluctuation time interval if the maximum current difference value is less than a first difference value threshold and the maximum voltage difference value is less than a second difference value threshold.

[0114] See also Figure 5 , Figure 5 The structural connection block diagram of a low-voltage distribution line operating parameter monitoring system provided by another optional embodiment of the present invention is shown. Figure 4In addition to the first measurement control module 11 shown, the second measurement control module 12 is also included, and the measuring device 1 is provided with a neutral wire terminal and a ground wire terminal;

[0115] The second measurement control module 12 is used to adjust the switching status of various internal disturbance loads multiple times, measure the current and voltage components generated by different disturbance loads connected to the neutral line, and measure the current and voltage components generated by different disturbance loads connected to the ground line, to obtain measurement data sets corresponding to different disturbance loads;

[0116] The drawing module 22 is further configured to associate the measurement data set with the corresponding measurement time and draw a curve diagram of the relationship between the measurement data set and time.

[0117] The above embodiment of the present invention achieves load regulation on the line by installing the measuring device 1 on the line and adjusting the switching status of various disturbance loads within the measuring device 1. Without user cooperation, the voltage, current, and impedance parameters under different loads can be monitored, which effectively improves convenience. The obtained monitoring data is graphically plotted against the time factor, improving monitoring quality. The obtained low-voltage distribution line operating parameter monitoring data can be used for at least:

[0118] 1) Compare the measured data set and time relationship curve with the impedance data and time curve of normal line operation to reflect the operation status of the low-voltage distribution network;

[0119] 2) Through the analysis of impedance data and time factor curve, the system can be set to automatically alarm when the impedance value is higher than the set upper limit or lower than the set lower limit;

[0120] 3) By comparing the impedance data and time element curves of the neutral and ground wires, it is possible to analyze the three-phase unbalanced neutral point voltage offset, line neutral or live wire disconnection, and other situations. For example, when the live wire is disconnected, it can be seen that the voltage of one phase relative to zero or to ground drops; by comparing the measured voltage relative to zero with the voltage relative to ground, it can be seen that the voltage measured on the three-phase live wire when the zero is disconnected is the neutral point voltage. The voltage of the neutral point offset is different, but the measured voltage relative to ground should be close to the same;

[0121] 4) Using parameters such as the external impedance of the measuring device 1, the value of the external impedance of the measuring device 1 during a relatively stable period (R resistance and X reactance) is obtained, the corresponding capacitance value is calculated according to the reactance value, and then the low-voltage compensation capacitor is input according to the capacitance value; this method can calculate the capacity that should be input for reactive power compensation and use this as a parameter to control the switching of reactive power compensation equipment on the low-voltage distribution line.

[0122] 5) Store the data for big data analysis.

[0123] Those skilled in the art can clearly understand that, for the convenience and conciseness of description, the specific working processes of the systems and modules described above can refer to the corresponding processes in the aforementioned method embodiments, and the specific beneficial effects of the systems and modules described above can refer to the corresponding beneficial effects in the aforementioned method embodiments, which will not be repeated here.

[0124] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for monitoring operating parameters of a low-voltage distribution line, characterized in that: The method comprises: A measuring device for disturbance loads with various known impedance parameters is installed on the low-voltage side of the low-voltage distribution line; By adjusting the switching states of various disturbance loads in the measuring device multiple times, measuring the voltage and current values ​​of each node in the measuring device under different disturbance loads, and obtaining measurement data groups under different disturbance loads; calculating an external impedance of the measuring device based on the measurement data set; Associating the measurement data group with the corresponding measurement time and drawing a graph of the relationship between the measurement data group and time, associating the calculated external impedance of the measuring device with the corresponding measurement time and drawing a graph of the relationship between the impedance and time; The method of adjusting the switching states of various disturbance loads in the measuring device multiple times and measuring the voltage and current values ​​of each node in the measuring device under different disturbance loads to obtain a measurement data group under different disturbance loads includes: Measuring the voltage and current values ​​of each node in the measuring device when all disturbance loads are not applied, to obtain a first measurement data group; After obtaining the first measurement data set, actively stimulating at least one disturbance load through the measurement device, measuring the voltage and current values ​​of each node inside the measurement device under the current disturbance load, and obtaining a second measurement data set; After obtaining the second measurement data set, the measurement device actively removes or increases the disturbance load, measures the voltage and current values ​​of each node inside the measurement device under the current disturbance load, and obtains a third measurement data set; After obtaining the third measurement data set, the measurement device actively removes or increases the disturbance load, measures the voltage and current values ​​of each node inside the measurement device under the current disturbance load, and obtains a fourth measurement data set; Calculating the external impedance of the measuring device according to the measurement data group includes: Comparing the difference between the first measurement data group and the fourth measurement data group, and determining whether the measurement time corresponding to each measurement data group is within the continuous small and micro load fluctuation time interval according to the obtained difference comparison result, to obtain a corresponding determination result; If the determination result is yes, determining that the external impedances of the measurement devices corresponding to the various measurement data groups are substantially equal, and selecting any one measurement data group from the first measurement data group, the second measurement data group, the third measurement data group, and the fourth measurement data group to calculate the external impedance of the measurement device; The calculating the external impedance of the measuring device according to the measurement data set further includes: If the determination result is no, it is determined that the external impedances of the measurement devices corresponding to the measurement data groups are not equal, and the external impedances of the measurement devices corresponding to the first measurement data group, the second measurement data group, the third measurement data group, and the fourth measurement data group are calculated respectively.

2. The low-voltage distribution line operating parameter monitoring method according to claim 1, characterized in that: The comparing the difference between the first measurement data group and the fourth measurement data group, and determining whether the measurement time corresponding to each measurement data group is within the continuous small and micro load fluctuation time interval according to the obtained difference comparison result, includes: calculating a current difference value at each node between the first measurement data group and the fourth measurement data group, and determining a maximum current difference value therefrom; calculating voltage difference values ​​at each node between the first measurement data group and the fourth measurement data group, and determining a maximum voltage difference value therefrom; If the maximum current difference value is smaller than the first difference value threshold, and the maximum voltage difference value is smaller than the second difference value threshold, it is determined that the measurement time corresponding to each measurement data group is within the continuous small load fluctuation time interval.

3. The low-voltage distribution line operating parameter monitoring method according to claim 1, characterized in that: The method further comprises: Providing a neutral wire terminal and a ground wire terminal for the measuring device so that the measuring device has a fault variable simulation function; By adjusting the switching states of various disturbance loads in the measuring device multiple times, measuring the current and voltage components generated by different disturbance loads connected to the neutral line, and measuring the current and voltage components generated by different disturbance loads connected to the ground line, a measurement data set corresponding to different disturbance loads is obtained; The measurement data set is associated with the corresponding measurement time, and a curve diagram of the relationship between the measurement data set and time is drawn.

4. A low voltage distribution line operating parameter monitoring system, characterized in that: The system comprises: A measuring device is connected to the low-voltage side of a low-voltage distribution line, wherein a plurality of disturbance loads with known impedance parameters are installed inside the measuring device; the measuring device includes a first measurement control module; the first measurement control module is used to actively adjust the switching state of various internal disturbance loads, measure the voltage and current values ​​of each node inside the measuring device under different disturbance loads, and obtain measurement data sets under different disturbance loads; The monitoring platform includes a calculation module and a drawing module; the calculation module is used to calculate the external impedance of the measuring device based on the measurement data group; the drawing module is used to associate the measurement data group with the corresponding measurement time and draw a curve chart of the relationship between the measurement data group and time, and associate the calculated external impedance of the measuring device with the corresponding measurement time and draw a curve chart of the relationship between impedance and time; The first measurement control module includes: The first measuring unit is used to measure the voltage and current values ​​of each internal node when various disturbance loads are not put into use, so as to obtain a first measurement data group; a second measurement unit, configured to, after obtaining the first measurement data group, actively stimulate at least one disturbance load, measure the voltage and current values ​​of each node inside the measurement device under the current disturbance load, and obtain a second measurement data group; a third measuring unit, configured to, after obtaining the second measurement data group, actively remove or increase a disturbance load, measure voltage and current values ​​of each node inside the measurement device under the current disturbance load, and obtain a third measurement data group; a fourth measurement unit, configured to, after obtaining the third measurement data group, actively remove or increase a disturbance load, measure voltage and current values ​​of each node within the measurement device under the current disturbance load, and obtain a fourth measurement data group; The calculation module includes: a comparison and determination unit, configured to compare the difference between the first measurement data group and the fourth measurement data group, and determine whether the measurement time corresponding to each measurement data group is within a continuous small and micro load fluctuation time interval based on the obtained difference comparison result, thereby obtaining a corresponding determination result; a first calculation unit, configured to, if the determination result is yes, determine that the external impedances of the measurement devices corresponding to the various measurement data groups are substantially equal, and select any one measurement data group from the first measurement data group, the second measurement data group, the third measurement data group, and the fourth measurement data group to calculate the external impedance of the measurement device; The calculation module also includes: The second calculation unit is configured to, if the determination result is negative, determine that the external impedances of the measurement devices corresponding to the measurement data groups are not equal, and respectively calculate the external impedances of the measurement devices corresponding to the first measurement data group, the second measurement data group, the third measurement data group, and the fourth measurement data group.

5. The low-voltage distribution line operating parameter monitoring system according to claim 4, characterized in that: The comparison and determination unit includes: a first sub-calculation unit, configured to calculate a current difference value at each node between the first measurement data group and the fourth measurement data group, and determine a maximum current difference value therefrom; a second sub-calculation unit, configured to calculate voltage difference values ​​at each node between the first measurement data group and the fourth measurement data group, and determine a maximum voltage difference value therefrom; The determination subunit is configured to determine that the measurement time corresponding to each measurement data group is within a continuous small load fluctuation time interval if the maximum current difference value is less than a first difference value threshold and the maximum voltage difference value is less than a second difference value threshold.

6. The low-voltage distribution line operating parameter monitoring system according to claim 4, characterized in that: The measuring device is provided with a neutral wire terminal and a ground wire terminal; The measuring device further includes a second measurement control module; the second measurement control module is used to measure the current and voltage components generated by different disturbance loads being connected to the neutral line, and the current and voltage components generated by different disturbance loads being connected to the ground line, by adjusting the switching states of various internal disturbance loads multiple times, to obtain measurement data sets corresponding to different disturbance loads; The drawing module is further configured to associate the measurement data set with the corresponding measurement time, and draw a curve diagram of the relationship between the measurement data set and time.

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