A method and device for metering phase power of a three-phase system and a storage medium

Abstract

The application provides a three-phase system phase power metering method and device and a storage medium, steps 1, data is acquired by using a two-meter method, step 2, three sets of logical judgment conditions are set, step 3, the validity of the delta value is verified by using a preset phase difference angle interval table, step 4, the initial phase and voltage of the A and C phases are calculated, and step 5, the active power of the three phases is calculated. The metering device comprises a measuring instrument, a communication acquisition module and a data processing unit, the data processing unit comprises an interval judgment module, a conversion operation module, a separate phase power solving module and an output module. Effect: no additional hardware investment is needed, no current transformer needs to be additionally installed, the device has strong universality, the metering precision meets the demand of regulation and control, and the device is suitable for a wide range of scenes.

Description

Technical Field

[0001] This invention belongs to the field of power metering and power regulation technology, and relates to the technology for calculating the active power of a three-phase three-wire system. Background Technology

[0002] New energy storage technologies have become core equipment supporting the consumption of new energy sources and enhancing the grid's flexible regulation capabilities. They are widely used on the grid side, power source side, user side, industrial and commercial parks, and integrated photovoltaic-storage-charging distribution areas. In scenarios involving power quality management and backflow prevention for energy storage in distribution areas, energy storage control equipment needs to acquire the active power of each phase (A, B, and C) and precisely control the charging and discharging power of the energy storage to prevent backflow of power into the grid.

[0003] Currently, high-voltage power supply and metering dedicated transformers and public transformer substations generally use the three-phase three-wire two-meter method to measure electrical energy. The two-meter method only outputs the total active power of the three phases and cannot directly collect the active power of a single phase. If the total power is directly divided equally as the power of each phase, it will produce a large calculation error under the condition of unbalanced three-phase load, resulting in the failure of energy storage control logic and the failure of anti-reverse current control.

[0004] The existing solution involves installing three additional current transformers and power meters on the low-voltage side to collect phase power data. However, this solution has several drawbacks: First, the addition of transformers and metering instruments significantly increases hardware procurement costs; second, equipment installation requires power outages, which can cause significant economic losses to factories with continuous production or important load locations; third, if there are multiple load branches on the low-voltage side, the amount of equipment required needs to be multiplied, further increasing costs; and fourth, the measured data does not take into account the transformer's own losses, so the metering results still have inherent errors.

[0005] In summary, existing phase-by-phase power acquisition schemes involve large hardware investments, numerous construction restrictions, and significant metering errors. There is an urgent need for a metering scheme that can accurately calculate the active power of each phase without requiring additional hardware and relying solely on data collected from existing two-meter meters. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method and device for measuring phase power in a three-phase system. It relies solely on data collected from existing two-meter method electricity meters and uses a built-in dedicated algorithm to accurately calculate the active power of each of the three phases (A, B, and C). This eliminates the need for additional current transformers and metering instruments, reducing equipment, construction, and labor costs. It is suitable for various three-phase three-wire two-meter method application scenarios, such as energy storage regulation and backflow prevention, and power quality management.

[0007] The technical solution of this invention: a method for measuring phase power in a three-phase system, comprising the following steps: Step 1: Connect the measuring instrument to the three-phase line. Taking phase B as an example, use the two-meter method to obtain the following data: line voltage between phases A and B. Line voltage between phases C and B RMS value of phase current in phase A Effective value of C-phase current Line voltage and phase difference cosine value Line voltage and phase difference cosine value Three-phase total active power The cosine of the arctangent of the ratio of total reactive power to total active power ; Step 2: Set three sets of logical judgment conditions, with each condition outputting 0 or 1: Condition 1: If true, output 1; otherwise, output 0. Condition 2: If true, output 1; otherwise, output 0. Condition 3: If true, output 1; otherwise, output 0. The three sets of conditional output values ​​are combined to form a three-bit binary judgment code. Step 3: Preset phase difference angle interval lookup table, each set of three-bit binary judgment code corresponds to the positive and negative angle intervals of the phase difference angle δ; match the corresponding angle interval according to the three-bit binary judgment code, verify the validity of the δ value, and if the data is abnormal, re-collect the data from Step 1. pass Calculate the specific value of the phase difference angle δ; Step 4: Based on the δ value obtained in Step 3, consult the table of phase difference angles corresponding to different phase differences, and calculate the value using the corresponding formula. , The value is obtained through the phase offset relationship. , Calculate the initial phase of phase A voltage. The initial phase of phase C voltage According to the relationship between phase voltage and line voltage, , Calculate the effective value of phase voltage A. C-phase voltage RMS value ; Step 5: Calculate the active power of phase A using the following formula. Phase B active power C-phase active power : ; ; .

[0008] The phase difference angle range lookup table includes a positive angle range of 0° to 359° and a negative angle range of -359° to 0°. During matching, the system first checks whether δ falls within the positive angle range. If it does not fall within the positive angle range, it checks whether its opposite value matches the negative angle range to determine the correct match. , Final radian value.

[0009] A metering device for phase power of a three-phase system, used to perform the aforementioned method for metering phase power of a three-phase system, comprising: Measuring instruments used to measure three-phase three-wire metering data; The communication acquisition module connects to the measuring instrument via a 485 bus and reads the raw measurement data measured by the two-meter method measuring instrument. The data processing unit connects to the communication acquisition module via a 485 bus, receives and processes raw measurement data, and processes the raw measurement data through the following functional modules: The interval determination module is used to execute three sets of logical determination conditions to generate binary determination codes, match the phase difference angle interval and verify the data, and calculate the specific value of the phase difference angle δ. The conversion module is used to perform the conversion of line voltage to phase voltage amplitude and phase shift. The phase power calculation module is used to calculate the three-phase active power. The output module is used to display the three-phase active power separately or to send it to devices that need to adjust the power.

[0010] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for measuring the phase power of the three-phase system.

[0011] The beneficial effects of this invention are: 1. No new hardware investment: Data is collected using only the existing two-meter method on site, without the need to install current transformers or phase power meters, thus saving hardware procurement costs; 2. No power outage construction required: No on-site wiring or transformer installation is needed, avoiding economic losses to industrial and commercial enterprises and critical loads caused by power outages, shortening the on-site renovation period and reducing labor costs; 3. Strong algorithm versatility: The entire set of calculation logic can be directly ported to various power equipment such as energy storage EMS, energy storage control unit, and transformer area monitoring terminal. It is compatible with all three-phase three-wire two-meter metering systems. Only a simple phase sequence replacement is needed to be compatible with both common B phase and common C phase two-meter wiring methods. 4. Metering accuracy meets control requirements: Based on phasor phase correction logic, the phase power is calculated, which is fully adapted to the three-phase unbalanced load condition. The calculation results can be directly used for field control logic such as energy storage anti-backflow, peak regulation and frequency regulation, and power quality management. The field measured power curve has a high degree of matching with the actual load change trend. 5. Wide range of applicable scenarios: It covers all three-phase three-wire systems that require phase-by-phase power monitoring, including grid-side independent energy storage, power supply-side wind-solar-storage distribution, user-side industrial and commercial solar-storage-charging, and high-voltage power supply and metering dedicated transformer areas. Attached Figure Description

[0012] Figure 1 : A schematic diagram of the wiring for measuring the phase power of a three-phase system using the B-phase two-meter method according to the present invention; Figure 2 : Hardware module structure diagram of the three-phase system phase power metering device of the present invention; Figure 3 The real-time calculation curves of the phase active power of the three-phase system obtained by the method of the present invention. Detailed Implementation

[0013] A method for measuring phase power in a three-phase system, comprising the following steps: Step 1: Connect the measuring instrument to the three-phase line. Taking phase B as an example, the two-meter wiring method is as follows: Figure 1 The data that can be read is as follows: the line voltage between phases A and B. Line voltage between phases C and B RMS value of phase current in phase A Effective value of C-phase current Line voltage and phase difference cosine value Line voltage and phase difference cosine value Three-phase total active power The cosine of the arctangent of the ratio of total reactive power to total active power .

[0014] Step 2: Set three sets of logical judgment conditions, with each condition outputting 0 or 1: Condition 1: If true, output 1; otherwise, output 0. Condition 2: If true, output 1; otherwise, output 0. Condition 3: If true, output 1; otherwise, output 0. The three sets of conditional output values ​​are combined to form a three-bit binary judgment code.

[0015] Step 3: Preset a phase difference angle interval lookup table. Each set of three-bit binary judgment codes corresponds to two sets of positive and negative angle intervals of the phase difference angle δ. Match the corresponding angle interval according to the three-bit binary judgment code, verify the validity of the δ value, and re-collect the data from Step 1 if the data is abnormal.

[0016] pass The specific value of the phase difference angle δ is calculated.

[0017] Table 1. Comparison Table of Phase Difference Angle Ranges

[0018] Step 4: Based on the δ value obtained in Step 3, look up the table of phase difference angles corresponding to different phase differences.

[0019] Table 2. Relationship between different phase difference angles

[0020] Table 2 shows the phase difference angle δ intervals and their corresponding calculation formulas. To simplify the table, the letters M and N represent the inverse cosine formulas.

[0021] , .

[0022] Calculate based on the formula found. , The value is obtained through the phase offset relationship. , Calculate the initial phase of phase A voltage. The initial phase of phase C voltage According to the relationship between phase voltage and line voltage, , Calculate the effective value of phase voltage A. C-phase voltage RMS value .

[0023] Step 5: Calculate the active power of phase A. Phase B active power C-phase active power The formula is as follows: ; ; .

[0024] Substituting the result from step 4 , , , Step 1 , , and thus , , .

[0025] The phase difference angle range lookup table includes a positive angle range of 0° to 359° and a negative angle range of -359° to 0°. During matching, the system first checks whether δ falls within the positive angle range. If it does not fall within the positive angle range, it checks whether its opposite value matches the negative angle range to determine the correct match. , Final radian value.

[0026] Calculation Example: The first three columns of Table 1 are 1, 1, 0, δ=20°, corresponding to the intervals (0, 60) and (-359, -300). Since the positive angle interval is satisfied, δ is taken as 20. The values ​​in Table 2 are M and -N respectively. The first three columns are 0, 0, 1, δ=160°, corresponding to the intervals (180, 240) and (-180, -120). The negative number -160° has a corresponding interval, so δ is taken as -160. The values ​​in Table 2 are -M and N-2*3.14 respectively. Then, according to the formula in step 5, calculate the active power of phase A. Phase B active power C-phase active power .

[0027] In field application, the three-phase power was obtained according to the method of this invention, and the curves are as follows: Figure 3 As shown, the data uploaded using the "two-table method" is processed and calculated to... , , The three-phase power values ​​reduce equipment investment, installation, manpower, and time costs, and the obtained data meets the on-site control requirements, allowing for on-site operation and verification.

[0028] Although this technology was researched and tested based on the "high-voltage supply and high-voltage metering" energy storage equipment scenario, it is applicable to all two-meter metering systems. The "two-meter method" uses an algorithm formula given for common phase B. If the measurement is for common phase C, simply treat the original phase A as phase C, phase B as phase A, and phase C as phase B and apply the formula.

[0029] like Figure 2 As shown, a metering device for phase power of a three-phase system is used to perform the aforementioned method for metering phase power of a three-phase system, comprising: Measuring instruments used to measure three-phase three-wire metering data; The communication acquisition module connects to the measuring instrument via a 485 bus and reads the raw measurement data measured by the two-meter method measuring instrument. The data processing unit connects to the communication acquisition module via a 485 bus, receives and processes raw measurement data, and processes the raw measurement data through the following functional modules: The interval determination module is used to execute three sets of logical determination conditions to generate binary determination codes, match the phase difference angle interval and verify the data, and calculate the specific value of the phase difference angle δ. The conversion module is used to perform the conversion of line voltage to phase voltage amplitude and phase shift. The phase power calculation module is used to calculate the three-phase active power. The output module is used to display the three-phase active power separately or to send it to devices that need to adjust the power.

[0030] To facilitate widespread use, a computer-readable storage medium is provided, on which a computer program is stored. When executed by a processor, the computer program implements the method for measuring the phase power of a three-phase system. The computer program can be implanted as a calculation plug-in into equipment capable of measuring active power using the "two-meter method," such as energy storage control units and energy storage EMS devices, to obtain the required power data.

Claims

1. A method for measuring phase power in a three-phase system, characterized in that: Step 1: Connect the measuring instrument to the three-phase line. Taking phase B as an example, use the two-meter method to obtain the following data: line voltage between phases A and B. Line voltage between phases C and B RMS value of phase current in phase A Effective value of C-phase current Line voltage and phase difference cosine value Line voltage and phase difference cosine value Three-phase total active power The cosine of the arctangent of the ratio of total reactive power to total active power ; Step 2: Set three sets of logical judgment conditions, with each condition outputting 0 or 1: Condition 1: If true, output 1; otherwise, output 0. Condition 2: If true, output 1; otherwise, output 0. Condition 3: If true, output 1; otherwise, output 0. The three sets of conditional output values ​​are combined to form a three-bit binary judgment code. Step 3: Preset phase difference angle interval lookup table, each set of three-bit binary judgment code corresponds to the positive and negative angle intervals of the phase difference angle δ; match the corresponding angle interval according to the three-bit binary judgment code, verify the validity of the δ value, and if the data is abnormal, re-collect the data from Step 1. pass Calculate the specific value of the phase difference angle δ; Step 4: Based on the δ value obtained in Step 3, consult the table of phase difference angles corresponding to different phase differences, and calculate the value using the corresponding formula. , The value is obtained through the phase offset relationship. , Calculate the initial phase of phase A voltage. The initial phase of phase C voltage According to the relationship between phase voltage and line voltage, , Calculate the effective value of phase voltage A. C-phase voltage RMS value ; Step 5: Calculate the active power of phase A using the following formula. Phase B active power C-phase active power : ； ； 。 2. The method for measuring phase power in a three-phase system according to claim 1, characterized in that: The phase difference angle range lookup table includes a positive angle range of 0° to 359° and a negative angle range of -359° to 0°. During matching, the system first checks whether δ falls within the positive angle range. If it does not fall within the positive angle range, it checks whether its opposite value matches the negative angle range to determine the correct match. , Final radian value.

3. A metering device for phase power in a three-phase system, characterized in that, A method for measuring the phase power of a three-phase system as described in claim 1 or 2, comprising: Measuring instruments used to measure three-phase three-wire metering data; The communication acquisition module connects to the measuring instrument via a 485 bus and reads the raw measurement data measured by the two-meter method measuring instrument. The data processing unit connects to the communication acquisition module via a 485 bus, receives and processes raw measurement data, and processes the raw measurement data through the following functional modules: The interval determination module is used to execute three sets of logical determination conditions to generate binary determination codes, match the phase difference angle interval and verify the data, and calculate the specific value of the phase difference angle δ. The conversion module is used to perform the conversion of line voltage to phase voltage amplitude and phase shift. The phase power calculation module is used to calculate the three-phase active power. The output module is used to display the three-phase active power separately or to send it to devices that need to adjust the power.

4. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the method for measuring the phase power of a three-phase system as described in claim 1 or 2.

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