Method for judging lead and lag of voltage and current in three-phase power

Abstract

The invention provides a method for judging lead and lag of voltage and current in three-phase power, which comprises the following five steps of: acquiring data, determining parameters, calculating single-phase reactive power and total reactive power, establishing a clock set and counting, and obtaining a result. The method for judging lead and lag of voltage and current in three-phase power provided by the invention solves the problems that when an oscilloscope is used, the oscilloscope is easily interfered by various noises in the environment, the waveform displayed on the oscilloscope is distorted, the original clear and stable waveform becomes fuzzy, distorted and even cannot be recognized, and the changes cannot be captured in real time, so that the time is shortened. And the change of reactive power is displayed in a clock set mode, so that the lead-lag relationship between the voltage and the current becomes intuitive and easy to understand, the analysis difficulty is reduced, and the method has the advantages of wide application range, high adaptability and the like.

Description

Technical Field

[0001] The invention relates to the field of three-phase electricity measurement, and in particular to a method for distinguishing the leading and lagging of voltage and current in three-phase electricity. Background Art

[0002] Three-phase alternating current is a common occurrence in our lives. In certain environments, due to the load of high-power electrical equipment, three-phase electricity is needed. It is a form of electric energy transmission, referred to as three-phase electricity. Three-phase alternating current power supply is a power supply composed of three alternating potentials with the same frequency, equal amplitude, and phase difference of 120 degrees.

[0003] Three-phase electricity is widely used in industry, agriculture and commerce due to its advantages such as high power factor, smooth power supply, high efficiency and low line cost. In the use of industrial machinery such as pumps, fans, compressors, etc. and commercial equipment, the equipment requires a large starting torque and operating power, and three-phase electricity can meet these needs well. The phases in the three-phase power system are offset from each other by 120 degrees. When the load is evenly distributed on all three phases, the current will not be concentrated on any one wire, thus avoiding overload and waste of electricity. The power transmission efficiency of three-phase electricity is higher than that of single-phase electricity, because the offset of the phases in the three-phase system is combined to produce a rotating magnetic field, thereby reducing power loss. In addition, three-phase power systems usually have higher reliability. If one phase fails, the other two phases can still provide power, thereby ensuring the normal operation of the equipment.

[0004] However, the existing three-phase electricity will lead or lag the voltage and current when it is used. Whether the voltage leads the current or the current leads the voltage, it will bring the following effects:

[0005] 1. Cause the power factor to drop: This causes a large reactive power loss during the transmission and use of electric energy. The power department will adjust the electricity fee according to the power factor. The decrease in power factor will cause users to bear a certain amount of power adjustment fee fines;

[0006] 2. Grid instability: The lead and lag of voltage and current may cause instability in the grid, such as voltage fluctuations and current harmonics. These unstable factors will affect the normal operation of the grid and may even cause grid failures in severe cases. The instability of the grid will damage electrical equipment and shorten the service life of the equipment.

[0007] 3. Reduced system efficiency: The lead and lag of voltage and current will lead to reduced system efficiency. In the power system, electric energy needs to go through multiple links for transmission and distribution, and the lead and lag of voltage and current will increase the energy loss in these links, thereby reducing the overall efficiency of the system.

[0008] There are existing methods for judging the lead and lag of voltage and current in three-phase electricity, such as phase angle judgment method, oscilloscope observation method, etc. Among them, the oscilloscope observation method is used. The oscilloscope can display the waveforms of voltage and current. By observing the relative position of the waveform diagram, the lead and lag relationship of voltage and current can be judged. However, when the oscilloscope observes three-phase electrical signals, it is easily interfered by various noises in the environment. For example, when using the oscilloscope detection method to detect three-phase circuits in a factory, the introduction of noise will cause the waveform displayed on the oscilloscope to be distorted. The originally clear and stable waveform will become blurred, distorted, or even unrecognizable. In addition, when the oscilloscope observes three-phase electrical signals, it usually takes a certain amount of time to capture and display the waveform. If a transient change or fault occurs in the three-phase electrical system, the oscilloscope may not be able to capture these changes in real time, resulting in missing important fault information. Therefore, it is not applicable.

[0009] Therefore, it is necessary to provide a new method for distinguishing the leading and lagging of voltage and current in three-phase electricity to solve the above technical problems. Summary of the invention

[0010] In order to solve the above technical problems, the present invention provides a method for distinguishing the leading and lagging of voltage and current in three-phase electricity.

[0011] The method for distinguishing the leading and lagging of voltage and current in three-phase electricity provided by the present invention comprises the following steps: S1, data acquisition: collecting three-phase voltage, setting appropriate sampling time and performing continuous acquisition, and obtaining multiple groups of three-phase voltages (u a ,u b ,u c ) The value of the neutral line voltage, and the inductive and capacitive loads in the statistical circuit;

[0012] S2. Determine parameters: According to the data collected by data acquisition, the inductive reactance X of the inductive load is obtained. l and the capacitive reactance X of the capacitive load c , and take one of the three-phase voltages (u a ,u b ,u c ) for analysis;

[0013] S3. Calculate the single-phase reactive power and the total reactive power:

[0014] S301, according to the obtained inductive reactance X of the inductive load l and the capacitive reactance X of the capacitive load c , calculate the single-phase reactive power Q of the inductive load l and single-phase reactive power Q of capacitive load c ;

[0015] S302, calculate the total inductive reactive power: Q L =3*Ql And the total capacitive reactive power: Q C =3*Q c , the total reactive power is obtained: Q 总 =Q L +Q C ;

[0016] S4. Create clock collection and statistics: Create a clock panel, and convert the standard three-phase voltage V 标 The total reactive power obtained is: Q 标 =Q L标 +Q C标 The value of is taken as the twelve o'clock direction of the clock. At this time, the value at twelve o'clock is 0, and the three-phase voltages measured in the continuous acquisition are calculated in sequence to obtain Q 总 , the calculated values ​​of Q 总 Statistics are added to different scales of the clock;

[0017] S5. Get the result: observe the scale on the clock surface and determine the leading or lagging direction;

[0018] It should be noted that by continuously collecting the three-phase voltage (u a ,u b ,u c ) and the neutral line voltage to ensure the comprehensiveness and continuity of the data, and to count the inductive and capacitive loads in the circuit to provide basic data for subsequent calculations.

[0019] Preferably, the single-phase reactive power Q of the inductive load is l The calculation formula is: Inductive load:

[0020] The single-phase reactive power Q of the capacitive load c The calculation formula is: Capacitive load:

[0021] Where v is the three-phase voltage (u a ,u b ,u c ) of the effective value, and the three-phase voltage (u a ,u b ,u c ) is calculated as follows:

[0022] Preferably, the standard three-phase voltage is V 标 =220V.

[0023] Preferably, in the result analysis, the leading direction: when the reactive power corresponding to a set of measured three-phase voltages is in the clockwise direction (i.e., the left side) of the clock, the three-phase voltage leads the standard three-phase voltage. At this time, the voltage leads the current, which is recorded as: the current lags relative to the voltage;

[0024] Lagging direction: When the reactive power corresponding to a set of measured three-phase voltages is located in the counterclockwise direction of the clock (i.e., the right side), the three-phase voltage lags behind the standard three-phase voltage. At this time, the voltage lags behind the current, which is recorded as: the current leads the voltage.

[0025] Preferably, the data acquisition is performed using a digital multimeter (DMM) for measurement.

[0026] Preferably, the continuous collection time is set to ten minutes, with collection once every one minute.

[0027] Preferably, the three-phase voltage is measured using a digital multimeter (DMM), and the specific operation steps are:

[0028] Step 1. First, check whether the test leads are intact and make sure there are no damaged or exposed wires. Switch the multimeter to the AC voltage (ACV) measurement mode and measure the three-phase voltage (u a ,u b ,u c ) to select the appropriate range;

[0029] Step 2. Insert the red probe of the digital multimeter (DMM) into the "V / Ω" jack of the multimeter, and the black probe into the "COM" jack of the multimeter;

[0030] Step 3. Measure the neutral point voltage and record the center line as: N, i.e. u a =u aN ,u b =u bN ,u c =u cN ;

[0031] Measure u aN :Touch the red test lead to the test point of phase A (Ua), touch the black test lead to the test point of the neutral line (N), and read the voltage value u displayed on the multimeter at this time a ;

[0032] Measure u bN :Touch the red test lead to the test point of phase B (Ub), touch the black test lead to the test point of the neutral line (N), and read the voltage value u displayed on the multimeter at this time b ;

[0033] Measure u cN:Touch the red test lead to the test point of phase C (Uc), touch the black test lead to the test point of the neutral line (N), and read the voltage value u displayed on the multimeter at this time c .

[0034] Preferably, in the determination of the parameters, the type of load needs to be recorded, and the positions and quantities of the inductive load and the capacitive load are recorded according to the circuit diagram, and the inductive reactance X is calculated by the known load parameters, that is, the values ​​of the inductance value L and the capacitance value C. l and capacitive reactance X c .

[0035] Preferably, the inductive reactance X l The calculation formula is: l =2πfL, the capacitive reactance X c The calculation formula is Where L is the known inductance value and C is the capacitance value, and f is the country's grid frequency, which is 50HZ.

[0036] Preferably, the clock set and statistics are established, and the clock is first divided into 12 scales, representing the reactive power variation range within a cycle, and the calculated reactive power difference Q is calculated. 总 -Q 标 , and map the calculated reactive power difference result to the corresponding scale of the clock.

[0037] Preferably, after being mapped to the corresponding scale of the clock, the reactive power difference corresponding to each set of data needs to be recorded, marked on the clock, and a clock graph is drawn.

[0038] Preferably, in the result judgment, when Q 总 >Q 标 , it means clockwise, that is, the voltage leads the current. When Q 总 标 , it indicates counterclockwise direction, that is, voltage lags behind current.

[0039] Compared with the related art, the method for distinguishing the leading and lagging of voltage and current in three-phase electricity provided by the present invention has the following beneficial effects:

[0040] 1. Displaying the change of reactive power by means of clock collection makes the lead-lag relationship between voltage and current intuitive and easy to understand, reducing the difficulty of analysis.

[0041] ​2. The method of using reactive power for comparative calculation is based on detailed data collection and precise calculation process, and the results obtained are of high accuracy, which can provide a reliable basis for system adjustment. It can be used well even in noisy environments or some emergency situations. It solves the problem that the use of oscilloscopes is easily disturbed by various noises in the environment, which will cause the waveform displayed on the oscilloscope to be distorted. The originally clear and stable waveform will become blurred, distorted, or even unrecognizable, and these changes cannot be captured in real time, resulting in missing important fault information.

[0042] 3. Through continuous measurement and calculation, it can reflect the changes in the system's reactive power in real time, making it easy to discover and deal with potential problems in a timely manner, and it is real-time.

[0043] 4. This method of distinguishing the leading and lagging voltage and current in three-phase electricity is applicable to various three-phase power systems. Whether in industrial production or daily life, it can be effectively analyzed and adjusted. It has a wide range of uses, is easy to use, and has high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A flow chart of the overall method for determining the leading and lagging of voltage and current in three-phase electricity provided by the present invention;

[0045] Figure 2 This is the operation flow chart of the multimeter;

[0046] Figure 3 A flow chart of the method for determining the leading and lagging of voltage and current in three-phase electricity provided by the present invention;

[0047] Figure 4 It is a clock diagram for the equal total reactive power of inductive load and capacitive load under standard three-phase voltage;

[0048] Figure 5 This is a clock diagram showing that the voltage leads the current. Figure 1 ;

[0049] Figure 6 This is a clock diagram showing that the voltage leads the current. Figure 2 ;

[0050] Figure 7 This is a clock diagram where current leads voltage. DETAILED DESCRIPTION

[0051] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0052] Please refer to Figures 1 to 7 ,in, Figure 1 A flow chart of the overall method for determining the leading and lagging of voltage and current in three-phase electricity provided by the present invention; Figure 2This is the flow chart of the multimeter; Figure 3 A flow chart of the method for determining the leading and lagging of voltage and current in three-phase electricity provided by the present invention; Figure 4 It is a clock diagram for the equal total reactive power of inductive load and capacitive load under standard three-phase voltage; Figure 5 This is a clock diagram showing that the voltage leads the current. Figure 1 ; Figure 6 This is a clock diagram showing that the voltage leads the current. Figure 2 ; Figure 7 This is a clock diagram where current leads voltage.

[0053] In the specific implementation process, Figures 1 to 3 As shown, the following steps are included: S1, data acquisition: collect three-phase voltage, set appropriate sampling time and perform continuous acquisition to obtain multiple groups of three-phase voltages (u a ,u b ,u c ) The value of the neutral line voltage, and the inductive and capacitive loads in the statistical circuit;

[0054] S2. Determine parameters: According to the data collected by data acquisition, the inductive reactance X of the inductive load is obtained. l and the capacitive reactance X of the capacitive load c , and take one of the three-phase voltages (u a ,u b ,u c ) for analysis;

[0055] S3. Calculate the single-phase reactive power and the total reactive power:

[0056] S301, according to the obtained inductive reactance X of the inductive load l and the capacitive reactance X of the capacitive load c , calculate the single-phase reactive power Q of the inductive load l and single-phase reactive power Q of capacitive load c ;

[0057] S302, calculate the total inductive reactive power: Q L =3*Q l And the total capacitive reactive power: Q C =3*Q c , the total reactive power is obtained: Q 总 =Q L +Q C ;

[0058] S4. Create clock collection and statistics: Create a clock panel, and convert the standard three-phase voltage V 标 The total reactive power obtained is: Q 标 =Q L标 +Q C标The value of is taken as the twelve o'clock direction of the clock. At this time, the value at twelve o'clock is 0, and the three-phase voltages measured in the continuous acquisition are calculated in sequence to obtain Q 总 , the calculated values ​​of Q 总 Statistics are added to different scales of the clock;

[0059] S5. Get the result: observe the scale on the clock surface and determine the leading or lagging direction;

[0060] The above operation has the following explanation: the single-phase reactive power Q of the inductive load l The calculation formula is: Inductive load:

[0061] Single-phase reactive power Q of capacitive load c The calculation formula is: Capacitive load:

[0062] Where v is the three-phase voltage (u a ,u b ,u c ) and the three-phase voltage (u a ,u b ,u c ) is calculated as follows:

[0063] The standard three-phase voltage is V 标 =220V.

[0064] In the result analysis, the leading direction is: when the reactive power corresponding to a set of measured three-phase voltages is in the clockwise direction (i.e., the left side), the three-phase voltage leads the standard three-phase voltage. At this time, the voltage leads the current, which is recorded as: the current lags relative to the voltage;

[0065] Lagging direction: When the reactive power corresponding to a set of measured three-phase voltages is in the counterclockwise direction of the clock (i.e., the right side), the three-phase voltage lags behind the standard three-phase voltage. At this time, the voltage lags behind the current, which is recorded as: the current leads the voltage;

[0066] It should be noted that data acquisition: by continuously collecting three-phase voltage (u a ,u b ,u c ) and the value of the neutral line voltage to ensure the comprehensiveness and continuity of the data, and to count the inductive load and capacitive load in the circuit to provide basic data for subsequent calculations;

[0067] Determine the parameters: Select a set of three-phase voltage (u a ,u b ,u c) to conduct in-depth analysis, simplifying calculations and maintaining the accuracy of analysis;

[0068] Single-phase and total reactive power: Calculate the single-phase reactive power of inductive load and capacitive load respectively, and then get the total inductive reactive power Q L And the total capacitive reactive power Q C , the total reactive power Q is obtained by adding 总 ;

[0069] Establish a clock set and statistics: use the total reactive power (based on 0) as the twelve o'clock direction of the clock to intuitively display the changes in reactive power, and continuously measure and calculate the reactive power values ​​corresponding to the three-phase voltage within ten minutes, and count them on different scales of the clock to form a dynamic reactive power change graph.

[0070] It should be further explained that, through continuous measurement and calculation, the changes in the reactive power of the system can be reflected in real time, which is convenient for timely discovery and handling of potential problems. It has real-time characteristics, and the method of distinguishing the lead and lag of voltage and current in three-phase electricity is applicable to various three-phase electricity systems. Whether in industrial production or daily life, it can be effectively analyzed and adjusted, with a wide range of use and high accuracy.

[0071] refer to Figures 1 to 7 As shown, a digital multimeter (DMM) is used to perform measurements using data acquisition;

[0072] The continuous acquisition time is set to ten minutes, with acquisition once every one minute;

[0073] Use a digital multimeter (DMM) to measure the three-phase voltage. The specific steps are as follows:

[0074] Step 1. First, check whether the test leads are intact and make sure there are no damaged or exposed wires. Switch the multimeter to the AC voltage (ACV) measurement mode and measure the three-phase voltage (u a ,u b ,u c ) to select the appropriate range;

[0075] Step 2. Insert the red probe of the digital multimeter (DMM) into the "V / Ω" jack of the multimeter, and the black probe into the "COM" jack of the multimeter;

[0076] Step 3. Measure the neutral point voltage and record the center line as: N, i.e. u a =u aN ,u b =u bN ,u c =u cN ;

[0077] Measure u aN :Touch the red test lead to the test point of phase A (Ua), touch the black test lead to the test point of the neutral line (N), and read the voltage value u displayed on the multimeter at this time a ;

[0078] Measure u bN :Touch the red test lead to the test point of phase B (Ub), touch the black test lead to the test point of the neutral line (N), and read the voltage value u displayed on the multimeter at this time b ;

[0079] Measure u cN :Touch the red test lead to the test point of phase C (Uc), touch the black test lead to the test point of the neutral line (N), and read the voltage value u displayed on the multimeter at this time c ;

[0080] In determining the parameters, it is necessary to record the type of load, and according to the circuit diagram, record the location and quantity of the inductive load and the capacitive load, and calculate the inductive reactance X by the known load parameters, that is, the values ​​of the inductance value L and the capacitance value C. l and capacitive reactance X c ;

[0081] In the result judgment, when Q 总 >Q 标 , it means clockwise, that is, the voltage leads the current. When Q 总 标 , it indicates counterclockwise direction, that is, voltage lags behind current;

[0082] It should be noted that the continuous collection time is set to ten minutes, with collection once every one minute. The table is established based on the collected data as follows:

[0083]

[0084]

[0085] For example, in a three-phase circuit powered by the Chinese power grid, the frequency is 50Hz, and the following parameters are available: the inductance is 0.01H, the capacitance is 1uF, and the inductive reactance X is calculated. l and capacitive reactance X c :

[0086] S1. Calculate inductive reactance X l :X l =2πfL=2π×50×0.01≈3.14Ω

[0087] Calculate the capacitive reactance X c :

[0088] ​S2. According to the above table, the first set of data: A phase voltage: u a =230.1V, B phase voltage: u b =231.2V, C phase voltage: u c =229.8V.

[0089] Calculate the single-phase reactive power of inductive load:

[0090] Calculation of single-phase reactive power Q of capacitive load c :

[0091] S3. Calculate the total inductive reactive power: Q L =3*Q l ≈50673.3var

[0092] Calculate the total capacitive reactive power: Q C =3*Q c ≈50var

[0093] Total reactive power: Q 总 =Q L +Q C ≈50623.3var;

[0094] Thanks to Q 总 is a positive value, the total load presents an inductive characteristic, that is, the voltage leads the current and is located in the clockwise direction of the clock;

[0095] Calculating the other groups of data above, the total reactive power is:

[0096] The second group, total reactive power: Q 总 =Q L +Q C ≈50711.4 var;

[0097] The third group, total reactive power: Q 总 =Q L +Q C ≈50755.2var;

[0098] Group 8, total reactive power: Q 总 =Q L +Q C ≈50843.4 var;

[0099] Group 9, total reactive power: Q 总 =Q L +Q C ≈50711.4 var;

[0100] Group 10, total reactive power: Q 总 =Q L +Q C ≈50667.3var;

[0101] It should be noted that in an AC circuit, an inductive load will cause the current to lag behind the voltage, that is, the voltage phase leads the current phase, expressed as Q L >0; Capacitive load will cause the current to lead the voltage, that is, the current phase leads the voltage phase Q c <0, i.e. Q 总 =Q L +(-Q C );

[0102] It should be noted that the above total Q 总 All are positive values, and the total load presents inductive characteristics, that is, the voltage leads the current, and all are located in the clockwise direction of the clock;

[0103] It should be noted that the above calculation Figure 5 As shown, the solid clock arrow is Q under standard voltage 总 The first clock arrow in the clockwise direction indicates the minimum Q value calculated under the condition that the capacitance is 1uF. 总 The second clock arrow indicates that under the condition that the above capacitance is 1uF, the maximum Q value is calculated. 总 ;

[0104] It should be noted that when the above capacitance is 1mF, the inductive reactance X is calculated. l and capacitive reactance X c :

[0105] S1. Calculate inductive reactance X l :X l =2πfL=2π×50×0.01≈3.14Ω

[0106] Calculate the capacitive reactance X c :

[0107] S2. According to the above table, the first set of data: A phase voltage: u a =230.1V, B phase voltage: u b =231.2V, C phase voltage: u c =229.8V.

[0108] Calculate the single-phase reactive power of inductive load:

[0109] Calculation of single-phase reactive power Q of capacitive load c :

[0110] S3. Calculate the total inductive reactive power: Q L =3*Q l ≈50673.3var

[0111] Calculate the total capacitive reactive power: Q C =3*Q c ≈50035.9var

[0112] Total reactive power: Q 总 =Q L +Q C ≈637.4 var;

[0113] Thanks to Q 总 is a positive value, the total load presents an inductive characteristic, that is, the voltage leads the current and is located in the clockwise direction of the clock;

[0114] Calculating the other groups of data above, the total reactive power is:

[0115] The second group, total reactive power: Q 总 =Q L +Q C ≈638.5 var;

[0116] The third group, total reactive power: Q 总 =Q L +Q C ≈682.6 var;

[0117] Group 8, total reactive power: Q 总 =Q L +Q C ≈640.3var;

[0118] Group 9, total reactive power: Q 总 =Q L +Q C ≈638.5 var;

[0119] Group 10, total reactive power: Q 总 =Q L +Q C ≈638 var;

[0120] The above total Q 总 They are still all positive values, and the total load still presents inductive characteristics, that is, the voltage leads the current, and they are all located in the clockwise direction of the clock.

[0121] It should be noted that the above calculation Figure 6 As shown, the solid clock arrow is Q under standard voltage 总The first clock arrow in the clockwise direction indicates the minimum Q value calculated under the condition that the capacitance is 1mF. 总 The second clock arrow indicates that under the condition of the above capacitance of 1mF, the maximum Q calculated is 总 ;

[0122] It should be noted that when the above frequency is 50Hz, the following parameters are available: inductance is 0.01H, capacitance is 1.2mF, and the inductive reactance X is calculated at this time. l and capacitive reactance X c :

[0123] S1. Calculate inductive reactance X l :X l =2πfL=2π×50×0.01≈3.14Ω

[0124] Calculate the capacitive reactance X c :

[0125] S2. According to the above table, the first set of data: A phase voltage: u a =230.1V, B phase voltage: u b =231.2V, C phase voltage: u c =229.8V.

[0126] Calculate the single-phase reactive power of inductive load:

[0127] Calculation of single-phase reactive power Q of capacitive load c :

[0128] S3. Calculate the total inductive reactive power: Q L =3*Q l ≈50673.3var

[0129] Calculate the total capacitive reactive power: Q C =3*Q c ≈59886.8var

[0130] Total reactive power: Q 总 =Q L +Q C ≈-9213.5var;

[0131] Thanks to Q 总 It is a negative value, and the total load presents a capacitive characteristic, that is, the current leads the voltage and is located in the counterclockwise direction of the clock;

[0132] Calculating the other groups of data above, the total reactive power is:

[0133] The second group, total reactive power: Q 总 =Q L +Q C ≈-7017.2var;

[0134] The third group, total reactive power: Q 总 =Q L +Q C ≈-9394.2var;

[0135] Group 8, total reactive power: Q 总 =Q L +Q C ≈-9410.5var;

[0136] Group 9, total reactive power: Q 总 =Q L +Q C ≈-7017.2var;

[0137] Group 10, total reactive power: Q 总 =Q L +Q C ≈-9277.9var;

[0138] The above total Q 总 They are all negative values, and the total load presents capacitive characteristics, that is, the current leads the voltage and is located in the counterclockwise direction of the clock.

[0139] It should be noted that the above calculation Figure 7 As shown, the solid clock arrow is Q under standard voltage 总 The first clock arrow in the counterclockwise direction indicates the minimum Q value calculated under the condition that the capacitance is 1.2mF. 总 The second counterclockwise arrow indicates that under the condition that the capacitance is 1.2mF, the maximum Q value is calculated. 总 .

[0140] It should be further explained that by calculating the total reactive power, the load characteristics of the circuit can be better understood, thereby optimizing the load configuration, improving the efficiency and stability of the system, and by identifying the ratio of inductive load to capacitive load, measures can be taken to reduce the generation of reactive power, thereby reducing energy waste.

[0141] refer to Figure 1 , Figure 2 , Figure 3 as well as Figure 4 As shown, the clock set and statistics are established, and the clock is first divided into 12 scales, representing the reactive power variation range within a cycle, and the calculated reactive power difference Q is calculated. 总 -Q标 , mapping the calculated reactive power difference result to the corresponding scale of the clock;

[0142] After mapping to the corresponding scale of the clock, the reactive power difference corresponding to each set of data needs to be recorded, marked on the clock, and the clock graph is drawn;

[0143] It should be noted that by mapping the reactive power difference to the clock scale, it is easier to find periodic changes, abnormal fluctuations, and possible signs of failure, which helps engineers and technicians quickly locate the root cause of the problem and develop corresponding solutions;

[0144] It should be further explained that the clock collection format greatly enhances the visualization of reactive power changes, making complex data change trends clear at a glance, enhancing intuitiveness and facilitating understanding.

[0145] The working principle provided by the present invention is as follows: the lead and lag of voltage and current in three-phase electricity are determined by comparing the reactive power of capacitive load and inductive load, and the difference of reactive power is intuitively displayed by clock marking, which reduces the difficulty of analysis and enhances the accuracy of determination.

[0146] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any figure mark in the claims should not be regarded as limiting the claims involved.

[0147] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for determining the leading and lagging of voltage and current in three-phase electricity, characterized in that: The following steps are involved: S1. Data collection: Collect three-phase voltage, set appropriate sampling time and perform continuous collection, obtain multiple sets of three-phase voltage neutral line voltage values, and count the inductive load and capacitive load in the circuit; S2. Determine parameters: According to the data collected by data acquisition, the inductive reactance of the inductive load and the capacitive reactance of the capacitive load are obtained, and one set of three-phase voltages is taken for analysis; S3. Calculate the single-phase reactive power and the total reactive power: S301. Calculate the single-phase reactive power Q of the inductive load according to the obtained inductive reactance of the inductive load and the capacitive reactance of the capacitive load. l and single-phase reactive power Q of capacitive load c ; S302. Calculate the total inductive reactive power: Q L =3*Q l And the total capacitive reactive power: Q C =3*Q c , the total reactive power is obtained: Q 总 =Q L +Q C ; S4. Create clock collection and statistics: Create a clock panel, and convert the standard three-phase voltage V 标 The total reactive power obtained is: Q 标 =Q L标 +Q C标 The value of is taken as the twelve o'clock direction of the clock. At this time, the value at twelve o'clock is 0, and the three-phase voltages measured in the continuous acquisition are calculated in sequence to obtain Q 总 , the calculated values ​​of Q 总 Statistics are added to different scales of the clock; S5. Get the result: Observe the scale on the clock surface and determine the direction of advance or lag.

2. The method for determining the lead and lag of voltage and current in three-phase electricity according to claim 1, characterized in that: The data acquisition is performed using a digital multimeter.

3. The method for determining the lead and lag of voltage and current in three-phase electricity according to claim 1, characterized in that: The continuous acquisition time is set to ten minutes, with acquisition being performed every one minute.

4. The method for determining the lead and lag of voltage and current in three-phase electricity according to claim 2, characterized in that: The specific operation steps of using a digital multimeter to measure the three-phase voltage are as follows: Step 1. First check whether the test leads are intact and make sure there are no damaged or exposed wires. Switch the multimeter to AC voltage measurement mode and select the appropriate range according to the expected range of the three-phase voltage to be measured. Step 2. Use a multimeter to measure the neutral point voltage.

5. The method for determining the lead and lag of voltage and current in three-phase electricity according to claim 1, characterized in that: In the determination of parameters, it is necessary to record the type of load, and based on the locations and quantities of the inductive load and the capacitive load recorded according to the circuit diagram, the inductive reactance and the capacitive reactance are calculated using the known load parameters, namely the values ​​of the inductance and the capacitance.

6. The method for determining the lead and lag of voltage and current in three-phase electricity according to claim 1, characterized in that: The clock set and statistics are established, and the clock is divided into 12 scales, representing the reactive power variation range in one cycle, and the calculated reactive power difference Q is calculated. 总 -Q 标 , and map the calculated reactive power difference result to the corresponding scale of the clock.

7. The method for determining the leading and lagging of voltage and current in three-phase electricity according to claim 6, characterized in that: After being mapped to the corresponding scale of the clock, the reactive power difference corresponding to each set of data needs to be recorded, marked on the clock, and a clock graph is drawn.

8. The method for determining the lead and lag of voltage and current in three-phase electricity according to claim 1, characterized in that: In the result judgment, when Q 总 >Q 标 , it means clockwise, that is, the voltage leads the current. When Q 总 标 , it indicates counterclockwise direction, that is, voltage lags behind current.​

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