Intelligent electric power meter with voltage self-adaption function

Abstract

The invention provides an intelligent electric power meter with a voltage self-adaption function, and the meter comprises a voltage sampling circuit which is used for collecting a voltage signal of a power grid; the processor is used for acquiring the power grid voltage signal acquired by the voltage sampling circuit and judging a voltage grade corresponding to the power grid voltage signal according to a preset voltage grade judgment rule; determining an ammeter wiring mode and a rated voltage value according to the judged voltage grade; and according to the determined rated voltage value, calling a corresponding meter adjusting parameter, and metering the power grid voltage signal. According to the intelligent electric meter, the simple voltage sampling circuit is used, rapid voltage self-adaption is achieved, the requirements of wide voltage range, multiple voltage grades and multiple wiring modes of an overseas electric power system can be met, and the universality and applicability of the intelligent electric meter are improved.

Description

Technical Field

[0001] The invention relates to the field of electric energy meters, in particular to an intelligent electric energy meter with a voltage self-adaptation function. Background Art

[0002] Smart power meters face huge challenges when applied in different power systems around the world. The voltage ranges, levels and wiring methods of power grids in different countries vary significantly, making it difficult for meters to adapt to diverse working environments; each wiring method and voltage level will have a huge impact on the operation of smart power meters.

[0003] Traditional meters are often only applicable to specific voltage levels and wiring methods, and their versatility is limited. From a cost and manufacturing perspective, providing a specific smart power meter for each voltage level and wiring method is not conducive to controlling project costs and lacks flexibility.

[0004] When used on-site, if a smart power meter that does not meet the specifications is used or the meter is wired incorrectly, it will cause incorrect measurement and even damage the smart meter, leading to a safety accident.

[0005] How to design an intelligent power meter that can automatically identify and adapt to different voltage levels and wiring methods has become a technical problem that needs to be solved urgently. Summary of the invention

[0006] The purpose of the present invention is to address the problem that overseas power systems have multiple voltage levels and wiring methods, and that smart power meters with only a single voltage specification can no longer meet on-site needs. An intelligent power meter with voltage self-adaptation function is proposed to provide accurate metering functions for overseas power systems.

[0007] The technical solution of the present invention is:

[0008] The present invention provides an intelligent power meter with a voltage self-adaptation function, the intelligent power meter comprising:

[0009] A voltage sampling circuit is used to collect grid voltage signals;

[0010] and a processor, which is used to obtain the grid voltage signal collected by the voltage sampling circuit, judge the voltage level corresponding to the grid voltage signal according to the preset voltage level judgment rule; and determine the meter wiring mode and rated voltage value according to the judged voltage level; and call the corresponding meter adjustment parameters according to the determined rated voltage value to measure the grid voltage signal.

[0011] Furthermore, the determination of the voltage level corresponding to the grid voltage signal comprises the following steps:

[0012] Obtaining the maximum voltage level and the minimum voltage level of the power grid, and classifying the voltage range between the maximum voltage level and the minimum voltage level according to a preset ratio to obtain a plurality of voltage level intervals;

[0013] The voltage value of the collected grid voltage signal is compared with each voltage level interval to determine in which voltage level interval the voltage value of the grid voltage signal is located, and the voltage level corresponding to the grid voltage signal is obtained.

[0014] Furthermore, the determination of the connection mode of the electric meter comprises the following steps:

[0015] If the AC two-phase power supply is used, the voltage angle between AB and AC in the power grid is obtained; if the ABC three-phase power supply is used, the voltage angle between any two phase voltages in the power grid is obtained to determine whether the voltage angle is within a first preset range and whether the voltage angle is within a second preset range;

[0016] If the voltage angle is neither within the first preset range nor within the second preset range, it is determined that the connection mode of the electric meter is a star connection mode;

[0017] If the voltage angle is within the first preset range or the second preset range, it is determined that the connection method of the electric meter is a triangle connection method.

[0018] Furthermore, the processor is also used to delay for a first preset time length when the electric meter is connected to the power grid for the first time, so as to wait for the power grid voltage to stabilize;

[0019] After the grid voltage is stable, the voltage value of each phase voltage is obtained and the voltage average value at multiple time points is calculated;

[0020] The maximum value among the calculated average values ​​of the phase voltages is taken as the voltage value of the grid voltage signal.

[0021] Furthermore, the calling of the corresponding meter adjustment parameters to measure the grid voltage signal includes the following steps:

[0022] The meter adjustment parameters under each voltage level that are pre-calibrated and stored are used. According to the voltage level corresponding to the grid voltage signal, the meter adjustment parameters of the corresponding voltage level are called to measure the collected grid voltage signal.

[0023] Furthermore, after determining the connection mode and rated voltage value of the electric meter, the processor controls the electric meter without powering off, performs adaptive switching based on the voltage level and connection mode, and starts the corresponding metering function.

[0024] Furthermore, the voltage sampling circuit includes a sampling resistor and a voltage divider resistor for accessing the grid voltage, the resistance values ​​of the sampling resistor and the voltage divider resistor meet the maximum input voltage that the meter can withstand, and the maximum value of the sampled voltage signal does not exceed the sampling voltage range of the meter processor.

[0025] Beneficial effects of the present invention:

[0026] In the present invention, the intelligent power meter with voltage self-adaptation function can meet the requirements of overseas power systems with wide voltage range, multiple voltage levels and multiple wiring modes. It can adapt to the grid voltage and wiring mode, provide accurate metering function and provide information such as rated voltage and wiring mode.

[0027] The intelligent power meter of the present invention stratifies the voltage levels in advance, adjusts the meter at the main voltage levels, and stores the parameters in a non-volatile memory. After the meter is powered on for the first time, the maximum voltage value is obtained through sampling calculation, and the rated voltage and wiring method are determined by comparing with the preset voltage range, and then the corresponding meter adjustment parameters are called for initialization; the star or triangle wiring method is determined by judging the phase voltage angle. This method uses a simple voltage sampling circuit to achieve fast voltage adaptation, meets the needs of complex power systems, and improves the versatility and applicability of intelligent power meters.

[0028] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0030] Figure 1 The schematic diagram of the A-phase voltage sampling circuit of the intelligent power meter with voltage self-adaptation function is shown.

[0031] Figure 2 The flowchart of the processor operation of the smart power meter with voltage adaptation function is shown. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0033] like Figure 1 , 2 As shown, the present invention provides an intelligent power meter with voltage self-adaptation function, the intelligent power meter comprising:

[0034] A voltage sampling circuit is used to collect grid voltage signals;

[0035] and a processor, configured to obtain the grid voltage signal collected by the voltage sampling circuit, determine the voltage level corresponding to the grid voltage signal according to a preset voltage level determination rule; and determine the meter wiring mode and the rated voltage value according to the determined voltage level; and call the corresponding meter adjustment parameter according to the determined rated voltage value to measure the grid voltage signal;

[0036] The specific steps include:

[0037] S1. Obtain the maximum voltage level and the minimum voltage level of the power grid in the region, and classify the maximum and minimum voltage levels into a level every 10% of the voltage level to obtain multiple voltage stratification intervals, wherein there is no overlap between each voltage level.

[0038] Specifically, according to the actual situation of the power grid in the region, the maximum voltage level Umax and the minimum voltage level Umin of the power grid in the region are obtained to obtain the voltage level range [Umin, Umax]. The equal-proportional segmentation method is adopted to grade [Umin, Umax] at a ratio of 10%, and n voltage stratification intervals [U1, U2], [U2, U3], ..., [Un-1, Un] are obtained, where U1 = Umin, Un = Umax. By checking the upper and lower boundaries of adjacent voltage stratification intervals, it is determined whether there is overlap. If there is overlap, the boundary value of the stratification interval is adjusted to ensure that there is no overlap between adjacent intervals.

[0039] S2. Use the same basic current to adjust the smart power meter at the main voltage level, obtain the meter adjustment parameters at different voltage levels, and write the meter adjustment parameters into different locations in the non-volatile memory respectively.

[0040] Specifically, the basic current Ib of the smart power meter is obtained, and the same Ib is used to adjust the meter separately in each voltage stratification interval to obtain the meter adjustment parameters under different voltage levels. The meter adjustment parameters corresponding to each voltage stratification interval are written into the corresponding storage area of ​​the non-volatile memory to establish a mapping relationship between the voltage stratification interval and the meter adjustment parameters.

[0041] S3. After the smart power meter is powered on for the first time, a preset time is delayed, the voltage of each phase is accumulated and calculated to obtain an average value of the voltage of each phase, and the maximum voltage value in the average value is obtained.

[0042] S4. Compare the maximum voltage value with a plurality of pre-stratified voltage stratification intervals to determine the voltage stratification interval in which the maximum voltage value is located, and obtain the rated voltage value and wiring method corresponding to the voltage stratification interval.

[0043] Specifically, the grid voltage U is collected in real time through the voltage sampling circuit, and U is compared with each voltage stratification interval to determine which voltage stratification interval U belongs to. If U belongs to the i-th voltage stratification interval, the rated voltage value and wiring method corresponding to the i-th voltage stratification interval are read from the i-th storage area of ​​the non-volatile memory.

[0044] S5. According to the rated voltage value, the meter adjustment parameter at the corresponding position in the non-volatile memory is called to initialize the metering function of the smart power meter to realize the voltage self-adaptation function of the smart power meter.

[0045] In one example, if the maximum voltage value meets the preset star connection condition, the connection mode is determined as a star connection mode; if the maximum voltage value does not meet the preset star connection condition, the connection mode is determined as a delta connection mode.

[0046] Specifically, the star connection condition and the triangle connection condition are preset, and the corresponding voltage threshold is set as the judgment condition of the star connection and the triangle connection according to the voltage level of the power grid and the characteristics of the connection mode. The maximum voltage value is compared with the preset star connection condition. If the maximum voltage value meets the star connection condition, the connection mode is determined to be the star connection mode. If the maximum voltage value does not meet the star connection condition, the maximum voltage value is compared with the preset triangle connection condition. If the triangle connection condition is met, the connection mode is determined to be the triangle connection mode.

[0047] The preset star connection conditions include: the angle between the AB two-phase voltage is not between 170° and 190°, and the angle between the AC two-phase voltage is not between 260° and 280°.

[0048] In this embodiment, the present invention can use the simplest voltage sampling circuit and quickly implement the voltage adaptation function using software to obtain the corresponding rated voltage value and wiring method, thereby meeting the requirements of overseas power systems with a wide voltage range, multiple voltage levels, and multiple wiring methods.

[0049] When implementing:

[0050] There are five types of low-voltage power systems in North America, as shown in Table 1, which are the characteristics of the five low-voltage power systems in North America, namely 1P2W power system, 1P3W power system, 2P3W power system, 3P4W star power system, and 3P4W triangle power system. The maximum line voltage does not exceed 600V.

[0051] Wiring method Phase voltage / V Line voltage / V Single-phase three-wire 120 208 Three-phase four-wire star 120 240 Three-phase three-wire triangle 230 400 Three-phase four-wire triangle 240 415 Three-phase two-wire triangle 277 480

[0052] The maximum low voltage power system in North America does not exceed 600V, so the voltage sampling circuit is Figure 1 As shown, this embodiment uses only AC power supply, where the sampling resistor is 1000Ω, the voltage divider resistor is 6 178kΩ, and differential sampling is used. The maximum input signal does not exceed 561mV, and the metering chips on the market can meet the requirements.

[0053] The main voltage levels are 120V, 230V and 277V. The same Ib is taken and the meter is adjusted at the same Ib point. The corresponding meter adjustment parameters are written into different locations of the non-volatile memory.

[0054] When the power system is a 230V 3P4W star system, the minimum voltage is 100V and the maximum voltage is 480V. The voltage levels are divided into 18 voltage stratification intervals: 110V, 121V, 133V, 146V, 160V, 177V, 194V, 214V, 235V, 259V, 284V, 313V, 344V, 379V, 417V, 458V, 503V, and 554V.

[0055] Connect the smart power meter to the power system, and after 8S, the maximum voltage value Umax of the three-phase voltage is 230V. Because it is an AC power supply method, only the voltage angle between AB and AC is used. First, determine whether the angle θab between the AB two-phase voltage is between 170° and 190°, that is, the angle is about 180°. Then determine whether the angle θac between the AC two-phase voltage is between 260° and 280°, that is, whether the angle meets 270°. In this power system, neither condition is met, so the wiring method is directly judged as 3P4W star wiring. Then compare the previously obtained Umax with the divided voltage levels. After comparing Umax one by one, it is found that it is between 214V and 235V. Therefore, the rated voltage is judged to be 230V. Finally, restart the metering and call the meter adjustment parameters under 230V. The voltage self-adaptation function can be completed within 10S.

[0056] When the power system is a 230V 3P4W triangle system, the minimum voltage is 100V and the maximum voltage is 480V. The voltage levels are divided into 18 voltage stratification intervals: 110V, 121V, 133V, 146V, 160V, 177V, 194V, 214V, 235V, 259V, 284V, 313V, 344V, 379V, 417V, 458V, 503V, and 554V.

[0057] Connect the smart power meter to the power system, and after 8S, the maximum voltage value Umax of the three-phase voltage is 230V. First, determine whether the angle θab between the AB two-phase voltage is between 170° and 190°, that is, the angle is about 180°. Then determine whether the angle θac between the AC two-phase voltage is between 260° and 280°, that is, whether the angle satisfies 270°. In this power system, both conditions are met, so the wiring method is directly judged to be 3P4W triangle wiring. In this wiring method, the rated voltage is directly judged to be 115V. The rated voltage is fixed in this wiring method.

[0058] When the power system is a 3P4W star system and a 3P4W delta system, the error of the smart power meter after voltage adaptation is 0.038% and 0.063% under the 3P4W star system and the 3P4W delta system, which meet the requirements of a level 1 meter after a large number of tests.

[0059] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An intelligent power meter with voltage self-adaptation function, characterized in that: The smart power meter comprises: A voltage sampling circuit is used to collect grid voltage signals; and a processor, configured to obtain the grid voltage signal collected by the voltage sampling circuit, and determine the voltage level corresponding to the grid voltage signal according to a preset voltage level determination rule; and The wiring mode and rated voltage value of the electric meter are determined according to the determined voltage level; and the corresponding meter adjustment parameters are called according to the determined rated voltage value to measure the grid voltage signal.

2. The intelligent power meter with voltage self-adaptation function as claimed in claim 1, characterized in that: The step of determining the voltage level corresponding to the grid voltage signal comprises the following steps: Obtaining the maximum voltage level and the minimum voltage level of the power grid, and classifying the voltage range between the maximum voltage level and the minimum voltage level according to a preset ratio to obtain a plurality of voltage level intervals; The voltage value of the collected grid voltage signal is compared with each voltage level interval to determine in which voltage level interval the voltage value of the grid voltage signal is located, and the voltage level corresponding to the grid voltage signal is obtained.

3. The intelligent power meter with voltage self-adaptation function as claimed in claim 1, characterized in that: The method of determining the connection mode of the electric meter comprises the following steps: If the AC two-phase power supply is used, the voltage angle between AB and AC in the power grid is obtained; if the ABC three-phase power supply is used, the voltage angle between any two phase voltages in the power grid is obtained to determine whether the voltage angle is within a first preset range and whether the voltage angle is within a second preset range; If the voltage angle is neither within the first preset range nor within the second preset range, it is determined that the connection mode of the electric meter is a star connection mode; If the voltage angle is within the first preset range or the second preset range, it is determined that the connection method of the electric meter is a triangle connection method.

4. The intelligent power meter with voltage self-adaptation function according to any one of claims 1 to 3, characterized in that: The processor is also used to delay for a first preset time period when the electric meter is first connected to the power grid to wait for the power grid voltage to stabilize; After the grid voltage is stable, the voltage value of each phase voltage is obtained and the voltage average value at multiple time points is calculated; The maximum value among the calculated average values ​​of the phase voltages is taken as the voltage value of the grid voltage signal.

5. The intelligent power meter with voltage self-adaptation function as claimed in claim 1, characterized in that: The calling of the corresponding meter adjustment parameters to measure the grid voltage signal comprises the following steps: The meter adjustment parameters under each voltage level that are pre-calibrated and stored are used. According to the voltage level corresponding to the grid voltage signal, the meter adjustment parameters of the corresponding voltage level are called to measure the collected grid voltage signal.

6. The intelligent power meter with voltage self-adaptation function as claimed in claim 1, characterized in that: After determining the connection mode and rated voltage value of the electric meter, the processor controls the electric meter without powering off, performs adaptive switching based on the voltage level and connection mode, and starts the corresponding metering function.

7. The intelligent power meter with voltage self-adaptation function according to claim 1, characterized in that: The voltage sampling circuit includes a sampling resistor and a voltage divider resistor for accessing the grid voltage. The resistance values ​​of the sampling resistor and the voltage divider resistor meet the maximum input voltage that the meter can withstand, and the maximum value of the sampled voltage signal does not exceed the sampling voltage range of the meter processor.

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