Electric meter wiring detection method and three-phase inverter system

Abstract

The invention discloses an electric meter wiring detection method and a three-phase inverter system. The method can realize automatic detection of whether the electric meter wiring is correct or not. The detection operation is simple and fast, and the detection efficiency and detection accuracy can be improved. The method judges whether the connection phase sequence of the three-phase electric meter is correctly connected according to the power change at the output end of the three-phase inverter. The method comprises: reading the initial power measured by the three-phase electric meter, starting the A-phase pulse of the three-phase inverter for charging, collecting the first power, obtaining the first power maximum change phase and the change direction of the first power maximum change phase, starting the B-phase pulse of the three-phase inverter for charging, obtaining the second power maximum change phase and the change direction of the second power maximum change phase, starting the C-phase pulse of the three-phase inverter for charging, obtaining the third power maximum change phase and the change direction of the third power maximum change phase, and an external terminal judges whether the connection phase sequence of the A-phase, B-phase and C-phase is correct.

Description

Technical Field

[0001] The invention relates to the technical field of inverters, and in particular to an electric meter wiring detection method. Background Art

[0002] At present, in order to understand the household electricity consumption, it is necessary to connect an electric meter to the household photovoltaic energy storage grid-connected system. On the one hand, the power generation and consumption of the energy storage system can be adjusted according to the electricity consumption feedback from the electric meter to improve the utilization rate of photovoltaic energy; on the other hand, in the photovoltaic energy storage grid-connected system, the electric meter helps to realize the anti-backflow function.

[0003] When installing an electric meter in a three-phase energy storage inverter or grid-connected inverter, it is easy to have the phase sequence connected incorrectly or the positive and negative terminals of the internal current sensor connected in reverse. This not only causes errors in the real-time monitoring data of the system, such as the power value being opposite, but also may cause the photovoltaic inverter system to be unable to connect to the grid normally, and other system operation abnormalities. In more serious cases, the electric meter may be damaged. Therefore, when installing a three-phase electric meter, it is necessary to detect the connection of the electric meter.

[0004] At present, the installation and detection of three-phase meters are mainly performed by professional technicians. After installing the three-phase meter, professional technicians need to use tools such as volt-ampere phase meters to perform necessary wiring checks. This detection method is cumbersome, complicated to operate, and has low detection efficiency. In addition, when detecting, technicians need to determine whether the direction of the meter current sensor is connected in reverse based on the difference between the output power of the three-phase inverter and the power of the grid. The calculation of the difference increases the complexity of the phase sequence connection detection operation of the three-phase meter, and the calculation result is easily affected by subjective initiative, resulting in calculation errors and other problems, which affects the detection accuracy. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides an electric meter wiring detection method, which can realize automatic detection of whether the electric meter wiring is correct or not. The detection operation is simple and quick, and the detection efficiency and detection accuracy can be improved.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] A method for detecting the connection of an electric meter is implemented based on an electric meter detection system. The electric meter detection system comprises: a three-phase electric meter installed between a three-phase inverter and an input end of a power grid, and a controller. The controller is electrically connected to the three-phase inverter, and the controller is communicatively connected to the three-phase electric meter. The three-phase electric meter is used to collect the three-phase power of the input end of the power grid. The controller is used to send a driving pulse to a switch tube of an output phase of the three-phase inverter, and process the acquired power value. The method is characterized in that the method determines whether the connection phase sequence and direction of the three-phase electric meter are correctly connected according to the power change of each phase measured by the three-phase electric meter. The method comprises:

[0008] S1. When the three-phase inverter is not working, the initial power of the grid input terminal is read by the three-phase electric meter;

[0009] S2, sending a pulse to phase A of the three-phase inverter through the controller to turn on phase A of the three-phase inverter, while keeping phases B and C of the three-phase inverter in a closed state, collecting the first power of phases A, B and C through a three-phase electric meter, and sending it to the controller;

[0010] S3, comparing the initial power with the first power of each phase through the controller, obtaining the first power change amount and the first power change direction of the corresponding phase A, phase B, and phase C, and obtaining the first power maximum change phase and the change direction of the first power maximum change phase;

[0011] S4, sending a pulse to the B phase of the three-phase inverter through the controller to turn on the B phase of the three-phase inverter, while keeping the A phase and the C phase of the three-phase inverter in a closed state, and collecting the second power of the A phase, the B phase and the C phase through the three-phase meter;

[0012] S5. Compare the initial power with the second power of each phase through the controller to obtain the second power change amount and the second power change direction of the corresponding A phase, B phase, and C phase, and obtain the change direction of the second power maximum change phase and the second power maximum change phase;

[0013] S6, sending a pulse to the C phase of the three-phase inverter through the controller to turn on the C phase of the three-phase inverter, while keeping the A phase and the B phase of the three-phase inverter in a closed state, and collecting the third power of the A phase, the B phase and the C phase through the three-phase meter;

[0014] S7. Compare the initial power with the third power of each phase through the controller to obtain the third power change amount and the third power change direction of the corresponding phase A, phase B, and phase C, and obtain the phase with the largest third power change and the change direction of the phase with the largest third power change;

[0015] S8. The controller sends the acquired first power maximum change phase, second power maximum change phase, third power maximum change phase, change direction of the first power maximum change phase, change direction of the second power maximum change phase, and change direction of the third power maximum change phase to an external terminal. The external terminal determines whether the A phase wiring is correct according to the change directions of the first power maximum change phase and the first power maximum change phase, determines whether the B phase wiring is correct according to the change directions of the second power maximum change phase and the second power maximum change phase, and determines whether the C phase wiring is correct according to the change directions of the third power maximum change phase and the third power maximum change phase.

[0016] Its further characteristic is that

[0017] Furthermore, in steps S2, S4, and S6, the pulses of the corresponding phases A, B, and C are turned on by the controller respectively, and maintained for 5 seconds; when the controller controls the corresponding phase of the three-phase inverter to turn on, the active power reference value of the corresponding phase is set, and the active power reference value is less than or equal to 1 / 3 of the rated power;

[0018] Further, in step S4, after phase A is shut down and waits for 2 seconds, phase B pulse is turned on to charge the battery; in step S6, after phase B is shut down and waits for 2 seconds, phase C pulse is turned on to charge the battery;

[0019] Furthermore, in step S3, the specific method of obtaining the first power maximum change phase is: sorting the absolute values ​​of the first power change of phase A, the first power change of phase B, and the first power change of phase C, and the phase with the largest absolute value is the first power maximum change phase;

[0020] In step S5, the specific method of obtaining the second power maximum change phase is: sorting the absolute values ​​of the second power change of phase A, the second power change of phase B, and the second power change of phase C, and the phase with the largest absolute value is the second power maximum change phase;

[0021] In step S7, the specific method of obtaining the third power maximum change phase is: sorting the absolute values ​​of the third power change of phase A, the third power change of phase B, and the third power change of phase C, and the phase with the largest absolute value is the third power maximum change phase;

[0022] Further, in step S3, the first power variation refers to the difference between the first power of each phase and the corresponding initial power, and the first power of each phase includes: the first power of phase A, the first power of phase B, and the first power of phase C. The first power of phase A, the first power of phase B, and the first power of phase C are respectively subtracted from the corresponding initial power of phase A, the initial power of phase B, and the initial power of phase C to obtain the first power variation of each phase output, including the first power variation of phase A, the first power variation of phase B, and the first power variation of phase C; the first power change direction includes forward and reverse; if the first power variation is greater than zero, it indicates forward, and if the first power variation is less than zero, it indicates reverse;

[0023] In step S5, the second power variation refers to the difference between the second power of each phase and the corresponding initial power, and the second power of each phase includes: the second power of phase A, the second power of phase B, and the second power of phase C. The second power of phase A, the second power of phase B, and the second power of phase C are respectively subtracted from the corresponding initial power of phase A, the initial power of phase B, and the initial power of phase C to obtain the output power variation of each phase, including the second power variation of phase A, the second power variation of phase B, and the second power variation of phase C; the second power change direction includes forward and reverse; if the second power variation is greater than zero, it indicates forward, and if the second power variation is less than zero, it indicates reverse;

[0024] In step S7, the third power variation refers to the difference between the third power of each phase and the corresponding initial power, and the third power of each phase includes: the third power of phase A, the third power of phase B, and the third power of phase C. The third power of phase A, the third power of phase B, and the third power of phase C are respectively subtracted from the corresponding initial power of phase A, the initial power of phase B, and the initial power of phase C to obtain the output power variation of each phase, including the third power variation of phase A, the third power variation of phase B, and the third power variation of phase C; the third power change direction includes forward and reverse. If the third power variation is greater than zero, it indicates forward, and if the third power variation is less than zero, it indicates reverse;

[0025] Further, in step S8, if phase A is the first phase with the largest power change, then when the first power change amount of phase A is greater than zero, the change direction of the first phase with the largest power change is forward, indicating that the connection phase sequence and direction of phase A are correct; if phase A is the first phase with the largest power change, and the first power change amount of phase A is less than zero, then the change direction of the first phase with the largest power change is reverse, indicating that the connection phase sequence of phase A is correct but the direction is wrong; if phase A is not the first phase with the largest power change, and the change direction of the first phase with the largest power change is not the direction of the first power change amount of phase A, then it means that the connection phase sequence and direction of phase A are wrong, and the connection detection of phase A of the three-phase meter is realized;

[0026] If phase B is the second phase with the largest power change, then when the second power change of phase B is greater than zero, the change direction of the second phase with the largest power change is positive, indicating that the phase sequence and direction of the B phase connection are correct; if phase B is the second phase with the largest power change, and the second power change of phase B is less than zero, then the change direction of the second phase with the largest power change is reverse, indicating that the phase sequence of the B phase connection is correct but the direction is wrong; if phase B is not the second phase with the largest power change, and the change direction of the second phase with the largest power change is not the direction of the second power change of phase B, then the phase sequence and direction of the B phase connection are wrong, thus realizing the detection of the B phase connection of the three-phase meter;

[0027] If phase C is the third phase with the largest power change, then when the third power change amount of phase C is greater than zero, the change direction of the third phase with the largest power change is positive, indicating that the phase sequence and direction of the C phase connection are correct; if phase C is the third phase with the largest power change, and the third power change amount of phase C is less than zero, then the change direction of the third phase with the largest power change is reverse, indicating that the phase sequence of the C phase connection is correct but the direction is wrong; if phase C is not the third phase with the largest power change, and the change direction of the third phase with the largest power change is not the direction of the third power change amount of phase C, then it means that the phase sequence and direction of the C phase connection are wrong, thereby realizing the C phase connection detection of the three-phase meter.

[0028] A three-phase inverter system, wherein the three-phase inverter is a three-phase photovoltaic grid-connected inverter or a three-phase energy storage inverter, characterized in that one end of the three-phase photovoltaic inverter is connected to a photovoltaic array, one end of the three-phase energy storage inverter is respectively connected to the photovoltaic array and a battery, the other end of the three-phase photovoltaic grid-connected inverter or the three-phase energy storage inverter is connected to one end of a three-phase electric meter and a load, and the other end of the three-phase electric meter is connected to a power grid;

[0029] The above-mentioned electric meter connection detection method is applied to detect the connection condition of the three-phase electric meter in the three-phase inverter system.

[0030] Its further characteristic is that

[0031] Furthermore, the three-phase inverter is a three-phase four-wire structure: including phase A, phase B, phase C, and N line, and the N line is a ground line;

[0032] Furthermore, the electric meter detection system also includes a register, which is used to store the first maximum power change phase, the second maximum power change phase, the third maximum power change phase, the change direction of the first maximum power change phase, the change direction of the second maximum power change phase, and the change direction of the third maximum power change phase.

[0033] The above structure of the present invention can achieve the following beneficial effects: in the meter wiring detection method of the present application, the controller inputs pulses to each phase in the three-phase inverter respectively to control each phase in the three-phase inverter to start respectively, which is conducive to indirectly obtaining the output power change of each phase of the three-phase inverter and the output power change direction of each phase through the power change measured by the three-phase meter. The numerical value of the output power change is used to characterize whether the phase sequence connection of the meter of this phase is correct, and the positive and negative of the output power change is used to characterize whether the wiring direction of this phase of the three-phase inverter is correct. If the first power maximum change phase obtained according to the first power change is phase A, and the corresponding first power change direction of phase A is positive, that is, the change direction of the first power maximum change phase is positive, It indicates that the A phase sequence connection is correct and the positive and negative terminals of the A phase current sensor are correctly wired; similarly, if the second power maximum change phase obtained according to the second power change is the B phase, and the corresponding second power change direction of the B phase is positive, that is, the change direction of the second power maximum change phase is positive, then it indicates that the B phase sequence connection is correct and the B phase wiring direction is correct. Similarly, if the third power maximum change phase obtained according to the third power change is the C phase, and the corresponding third power change direction of the C phase is positive, that is, the change direction of the third power maximum change phase is positive, then it indicates that the C phase sequence connection is correct and the C phase wiring direction is correct, thereby realizing automatic detection of the phase sequence and wiring direction of the three-phase inverter meter, and the detection operation is convenient and quick, which effectively improves the detection efficiency.

[0034] In the meter wiring detection method of the present application, the calculation of the first power change, the second power change, and the third power change, as well as the determination of the first power maximum change phase, the second power maximum change phase, the third power maximum change phase, the change direction of the first power maximum change phase, the change direction of the second power maximum change phase, and the change direction of the third power maximum change phase are all automatically calculated and sorted by the controller in the three-phase inverter, which reduces the difficulty of the detection operation. Compared with the subjective calculation method of professional and technical personnel, the calculation method of the present application is not affected by subjective initiative, thereby improving the detection accuracy.

[0035] By adopting the meter wiring detection method of the present application, users can install the three-phase meter between the three-phase inverter and the power grid by themselves, and can directly obtain the first power maximum change phase, the second power maximum change phase, the third power maximum change phase, the change direction of the first power maximum change phase, the change direction of the second power maximum change phase, the change direction of the third power maximum change phase and the like through an external terminal, so as to know whether the wiring phase sequence and wiring direction of the installed three-phase meter are accurate. Therefore, after adopting the method of the present application in the three-phase inverter system, it is convenient for users to accurately install the three-phase meter by themselves, and there is no need for professional technicians to use tools such as volt-ampere phase meters to perform necessary wiring checks, thereby improving the convenience of installation and detection operations of the three-phase meter. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0037] Figure 1 It is a structural block diagram of a first embodiment of a three-phase inverter system of the present invention;

[0038] Figure 2 It is a structural block diagram of a second embodiment of a three-phase inverter system of the present invention;

[0039] Figure 3 1 is a control block diagram of a three-phase electric meter in Embodiment 1 of a three-phase inverter system of the present invention (the control method of the three-phase electric meter in Embodiment 2 is the same as the control method of the three-phase electric meter in Embodiment 1);

[0040] Figure 4 The present invention is a flow chart of the method for detecting the connection of an electric meter. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme 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 described embodiments 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 creative work should fall within the scope of protection of the present invention.

[0042] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product or equipment comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0043] In view of the technical problems in the prior art that after installing a three-phase electric meter, professional technicians need to use tools such as a volt-ampere phase meter to perform necessary wiring checks. This detection method has a cumbersome process, complex operation, and low detection efficiency. In addition, when detecting, the technicians need to determine whether the direction of the electric meter current sensor is connected in reverse based on the difference between the output power of the three-phase inverter and the power of the power grid. The calculation of the difference increases the complexity of the phase sequence connection detection operation of the three-phase electric meter, and the calculation result is easily affected by subjective initiative, resulting in calculation errors and the like, which affects the technical problem of detection accuracy. The present invention provides a specific application example of wiring detection of a three-phase inverter electric meter.

[0044] See Figure 1 Embodiment 1 provides a three-phase inverter system, in which the three-phase inverter is a three-phase photovoltaic grid-connected inverter, and the three-phase photovoltaic grid-connected inverter is a three-phase four-wire structure: including phase A, phase B, phase C, and line N, and line N is a grounding wire. The setting of the grounding wire facilitates the subsequent controller to control each phase of the three-phase photovoltaic grid-connected inverter separately, and the input end of the three-phase photovoltaic grid-connected inverter 2 is respectively connected to the photovoltaic array 1 and one end of the DC bus capacitor Cbus, and the output end of the three-phase photovoltaic grid-connected inverter 2 is respectively connected to the inductor and the input end of the three-phase electric meter 3 in turn, and the output end of the three-phase electric meter 3 is respectively connected to the power grid 5 and the controller 4. The controller 4 is connected to the external terminal through a wireless communication device or a wired communication device. In this embodiment, the external terminal is a computer, and the user checks the wiring detection status of the three-phase electric meter through the computer.

[0045] See Figure 2Embodiment 2 provides another three-phase inverter system, in which the three-phase inverter is a three-phase photovoltaic storage inverter, and the three-phase photovoltaic storage inverter is a three-phase four-wire structure: including phase A, phase B, phase C, and line N, and line N is a grounding wire. The setting of the grounding wire facilitates the subsequent controller to control each phase of the three-phase photovoltaic storage inverter separately. The input end of the three-phase photovoltaic storage inverter 8 is respectively connected to one end of the DC bus capacitor Cbus, the photovoltaic array 1, and the battery 6. The output end of the three-phase photovoltaic storage inverter 8 is respectively connected to the input end and the load of the three-phase electric meter 3. The output end of the three-phase electric meter 3 is respectively connected to the power grid 5 and the controller 4. The controller 4 is connected to the external terminal through a wireless communication device or a wired communication device. In this embodiment, the external terminal is a computer, and the user checks the wiring detection status of the three-phase electric meter through the computer.

[0046] See Figure 3 , Figure 4 The present application provides a meter wiring detection method, which is used to detect the wiring conditions of the three-phase meter in the above-mentioned embodiment 1 and embodiment 2. The detection method is implemented based on an meter detection system. The meter detection system includes the above-mentioned three-phase meter 3 and controller 4. The meter detection system also includes a register 7. The controller 4 is connected to the three-phase meter 3 through an RS485 communication line. The three-phase meter 3 is used to collect the power value of the power grid input end. The controller is used to send a drive pulse to the switch tube of the corresponding phase of the three-phase inverter, and process the acquired power value. The controller is connected to the register, and the register is used to store the first power maximum change phase, the second power maximum change phase, the third power maximum change phase, and the The changing direction of the first phase with the largest power change, the changing direction of the second phase with the largest power change, and the changing direction of the third phase with the largest power change. The meter wiring detection method determines whether the connection phase sequence and wiring direction of the three-phase meter are correct based on the power change measured by the three-phase meter. When the output end of the three-phase inverter is connected to a load, the power value measured by the three-phase meter is equal to the inverter output power value plus the load power value. When the load power value is constant, the inverter output power change value is equal to the power change value measured by the meter. Therefore, the inverter power change amount and change direction can be indirectly obtained through the power change of the three-phase meter, and the three-phase meter connection detection can be realized by controlling the output power change of the three-phase inverter.

[0047] The specific steps of the three-phase meter connection detection include: S1. When the three-phase inverter is not working, the initial power of the grid input end is read through the three-phase meter (in this embodiment, the initial power, the first power, the second power, and the third power of the grid input end read by the three-phase meter are the sum of the inverter output power and the load power. Under the condition of a certain load power, the power change of the three-phase meter is equal to the change of the inverter output power), and sent to the controller. The initial power includes: the initial power of phase A, the initial power of phase B, and the initial power of phase C.

[0048] S2. Send a pulse to phase A of the three-phase inverter through the controller to turn on phase A and maintain it for 5s, while keeping phases B and C of the three-phase inverter in the off state. After 5s, collect the first power of phases A, B, and C through the three-phase meter and send it to the controller. In Example 1, the three-phase photovoltaic grid-connected inverter is controlled by the DC bus voltage outer loop and the current inner loop. In Example 2, the three-phase photovoltaic storage inverter is controlled by the power outer loop and the current inner loop. When the controller controls the corresponding phase of the three-phase inverter in Example 1 or Example 2 to turn on, the active power reference value of the corresponding phase is set. The active power reference value is less than or equal to 1 / 3 of the rated power to ensure that the corresponding phase of the three-phase inverter has power output. In this embodiment, when each phase is controlled to be turned on, the active power reference value of the corresponding phase is set to 1 / 6 of the rated power. This ratio can be less than or equal to 1 / 3. Because the total output power of the three-phase inverter is the sum of the output power of each phase, so when the three-phase power is balanced, the output power of each phase is 1 / 3 of the total rated power. Therefore, the active power reference value of each phase is set to 1 / 6 of the rated power to ensure that the corresponding phase of the three-phase inverter has power output.

[0049] S3. Compare the initial power with the first power of each phase through the controller, obtain the first power change amount and the first power change direction of the corresponding A phase, B phase, and C phase, and obtain the first power maximum change phase and the change direction of the first power maximum change phase. Specifically, the first power change amount refers to the difference between the first power of each phase and the corresponding initial power. The first power of each phase includes: the first power of A phase, the first power of B phase, and the first power of C phase. Subtract the first power of A phase, the first power of B phase, and the first power of C phase from the corresponding initial power of A phase, the initial power of B phase, and the initial power of C phase respectively to obtain the first power change amount of each phase. The first power change amount includes the first power change amount of A phase, the first power change amount of B phase, and the first power change amount of C phase; the first power change direction includes forward and reverse;

[0050] According to the first power change of phase A, the first power change of phase B, and the first power change of phase C, the specific method of obtaining the phase with the largest first power change is: sort the absolute values ​​of the first power change of phase A, the first power change of phase B, and the first power change of phase C, and the phase with the largest absolute value is the phase with the largest first power change.

[0051] S4, after phase A stops and waits for 2 seconds, a pulse is sent to phase B of the three-phase inverter through the controller to turn on conduction B and maintain it for 5 seconds. At the same time, phase A and phase C of the three-phase inverter are still in the off state. After 5 seconds, the second power of phase A, phase B and phase C is collected through the three-phase electric meter.

[0052] S5. Compare the initial power with the second power of each phase through the controller, obtain the second power change amount and the second power change direction of the corresponding A phase, B phase, and C phase, and obtain the change direction of the second power maximum change phase. Specifically, the second power change amount refers to the difference between the second power of each phase and the corresponding initial power. The second power of each phase includes: the second power of A phase, the second power of B phase, and the second power of C phase. The second power of A phase, the second power of B phase, and the second power of C phase are subtracted from the corresponding initial power of A phase, the initial power of B phase, and the initial power of C phase to obtain the second power change amount of each phase. The second power change amount includes the second power change amount of A phase, the second power change amount of B phase, and the second power change amount of C phase; the second power change direction includes forward and reverse.

[0053] According to the second power change of phase A, the second power change of phase B, and the second power change of phase C, the specific method of obtaining the phase with the largest second power change is: sort the absolute values ​​of the second power change of phase A, the second power change of phase B, and the second power change of phase C, and the phase with the largest absolute value is the phase with the largest second power change.

[0054] S6, after the B phase is shut down and waits for 2 seconds, a pulse is sent to the C phase of the three-phase inverter through the controller to turn on the C phase and maintain it for 5 seconds. At the same time, the A phase and B phase of the three-phase inverter are still in the off state. After 5 seconds, the third power of the A phase, B phase and C phase is collected through the three-phase meter.

[0055] S7. Compare the initial power with the third power of each phase through the controller, obtain the third power change amount and the third power change direction of the corresponding A phase, B phase, and C phase, and obtain the third power maximum change phase and the change direction of the third power maximum change phase. Specifically, the third power change amount refers to the difference between the third power of each phase and the corresponding initial power. The third power of each phase includes: the third power of A phase, the third power of B phase, and the third power of C phase. The third power of A phase, the third power of B phase, and the third power of C phase are subtracted from the corresponding initial power of A phase, the initial power of B phase, and the initial power of C phase to obtain the third power change amount of each phase. The third power change amount includes the third power change amount of A phase, the third power change amount of B phase, and the third power change amount of C phase; the third power change direction includes forward and reverse.

[0056] According to the third power change of phase A, the third power change of phase B, and the third power change of phase C, the specific method of obtaining the phase with the largest third power change is: sort the absolute values ​​of the third power change of phase A, the third power change of phase B, and the third power change of phase C to obtain the phase with the largest third power change.

[0057] S8. The controller sends the acquired first power maximum change phase, second power maximum change phase, third power maximum change phase, change direction of the first power maximum change phase, change direction of the second power maximum change phase, and change direction of the third power maximum change phase to the external terminal. The external terminal determines whether the wiring of phase A is correct according to the change direction of the first power maximum change phase and the first power maximum change phase. Specifically, if the first power change amount is greater than zero, it indicates a forward direction; if the first power change amount is less than zero, it indicates a reverse direction; if phase A is the first power maximum change phase, then when the first power of phase A is When the rate change is greater than zero, the change direction of the first phase with the largest power change is positive, indicating that the connection phase sequence and direction of phase A are correct; if phase A is the first phase with the largest power change, and the first power change of phase A is less than zero, the change direction of the first phase with the largest power change is reverse, indicating that the connection phase sequence of phase A is correct but the connection direction of the positive and negative terminals of the internal current sensor is wrong; if phase A is not the first phase with the largest power change, and the change direction of the first phase with the largest power change is not the direction of the first power change of phase A, it means that the connection phase sequence and direction of phase A are wrong, thus realizing the connection detection of phase A of the three-phase meter. In this embodiment, according to the above comparison results, it can be seen that under the condition of step S3, if phase A is obtained as the first phase with the largest power change, and the change direction of the first phase with the largest power change of phase A is positive, then the connection of phase A is correct.

[0058] According to the second power change amount and the second power change direction, it is judged whether the B phase connection is correct. Specifically, if the second power change amount is greater than zero, it indicates a positive direction, and if the second power change amount is less than zero, it indicates a reverse direction; if the B phase is the second power maximum change phase, then when the second power change amount of the B phase is greater than zero, the change direction of the second power maximum change phase is a positive direction, indicating that the B phase connection phase sequence and direction are correct; if the B phase is the second power maximum change phase, the B phase second power change amount is less than zero, then the change direction of the second power maximum change phase is a reverse direction, indicating that the B phase connection phase sequence is correct but the direction is wrong; if the B phase is not the second power maximum change phase, the change direction of the second power maximum change phase is not the direction of the second power change amount of the B phase, indicating that the B phase connection phase sequence and direction are wrong, so as to realize the B phase connection detection of the three-phase meter. In this embodiment, according to the above comparison results, it can be seen that under the condition of step S4, if the B phase is obtained as the second power maximum change phase, and the change direction of the second power maximum change phase of the B phase is a positive direction, it indicates that the AB phase connection is correct.

[0059] Whether the connection of phase C is correct is determined according to the third power change amount and the third power change direction. Specifically, if the third power change amount is greater than zero, it indicates a positive direction, and if the third power change amount is less than zero, it indicates a reverse direction; if phase C is the third power maximum change phase, then when the third power change amount of phase C is greater than zero, the change direction of the third power maximum change phase is a positive direction, indicating that the connection phase sequence and direction of phase C are correct; if phase C is the third power maximum change phase, the third power change amount of phase C is less than zero, then the change direction of the third power maximum change phase is a reverse direction, indicating that the connection phase sequence of phase C is correct but the direction is wrong; if phase C is not the third power maximum change phase, the change direction of the third power maximum change phase is not the direction of the third power change amount of phase C, indicating that the connection phase sequence and direction of phase C are wrong, thus realizing the connection detection of phase C of the three-phase meter. In this embodiment, according to the above comparison results, it can be seen that under the condition of step S4, if phase C is obtained as the third power maximum change phase, and the change direction of the third power maximum change phase of phase C is a positive direction, it indicates that the connection of phase C is correct.

[0060] The above wiring detection method of the present application turns on the three-phase pulse voltage through the controller respectively, so that each phase works separately, so as to check whether the power change of the three-phase meter is consistent with the expected phase change. If not, it is judged that the three-phase meter is connected incorrectly. The present invention does not involve a large amount of calculation. The user only needs to check the power change of each phase through the external terminal to judge whether the phase sequence and direction of each phase of the three-phase meter are connected incorrectly. It is simple and easy to implement.

[0061] The above are only preferred embodiments of the present application, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the invention should be considered to be included in the scope of protection of the invention.

Claims

1. A method for detecting the connection of an electric meter, the method being implemented based on an electric meter detection system, the electric meter detection system comprising: A three-phase meter and a controller installed between a three-phase inverter and a power grid input terminal, wherein the controller is electrically connected to the three-phase inverter, and the controller is communicatively connected to the three-phase meter, and the three-phase meter is used to collect the three-phase power of the power grid input terminal, and the controller is used to send a driving pulse to a switch tube of a corresponding output phase of the three-phase inverter, and process the power. The method is characterized in that the method determines whether the connection phase sequence of the three-phase meter is correctly connected according to the power change measured by the three-phase meter, and the method comprises: S1. When the three-phase inverter is not working, the initial power of the grid input terminal is read by the three-phase electric meter; S2, sending a pulse to phase A of the three-phase inverter through the controller to turn on phase A of the three-phase inverter, while keeping phases B and C of the three-phase inverter in a closed state, collecting the first power of phases A, B and C through a three-phase electric meter, and sending it to the controller; S3, comparing the initial power with the first power of each phase through the controller, obtaining the first power change amount and the first power change direction of the corresponding phase A, phase B, and phase C, and obtaining the first power maximum change phase and the change direction of the first power maximum change phase; S4, sending a pulse to the B phase of the three-phase inverter through the controller to turn on the B phase of the three-phase inverter, while keeping the A phase and the C phase of the three-phase inverter in a closed state, and collecting the second power of the output end of the A phase, the B phase and the C phase through the three-phase meter; S5. Compare the initial power with the second power of each phase through the controller to obtain the second power change amount and the second power change direction of the corresponding A phase, B phase, and C phase, and obtain the change direction of the second power maximum change phase and the second power maximum change phase; S6, sending a pulse to the C phase of the three-phase inverter through the controller to turn on the C phase of the three-phase inverter, while keeping the A phase and the B phase of the three-phase inverter in a closed state, and collecting the third power of the output end of the A phase, the B phase and the C phase through the three-phase meter; S7. Compare the initial power with the third power of each phase through the controller to obtain the third power change amount and the third power change direction of the corresponding phase A, phase B, and phase C, and obtain the phase with the largest third power change and the change direction of the phase with the largest third power change; S8. The controller sends the acquired first power maximum change phase, second power maximum change phase, third power maximum change phase, change direction of the first power maximum change phase, change direction of the second power maximum change phase, and change direction of the third power maximum change phase to an external terminal. The external terminal determines whether the A phase wiring is correct according to the change directions of the first power maximum change phase and the first power maximum change phase, determines whether the B phase wiring is correct according to the change directions of the second power maximum change phase and the second power maximum change phase, and determines whether the C phase wiring is correct according to the change directions of the third power maximum change phase and the third power maximum change phase.

2. The method for detecting the connection of an electric meter according to claim 1, characterized in that: In steps S2, S4, and S6, the pulses of the corresponding A phase, B phase, and C phase of the three-phase inverter are turned on by the controller respectively and maintained for 5 seconds. When the controller controls the corresponding phase of the three-phase inverter to be turned on, the active power reference value of the corresponding phase is set, and the active power reference value is less than or equal to 1 / 3 of the rated power.

3. The method for detecting the connection of an electric meter according to claim 2, characterized in that: In step S4, after phase A is shut down and waits for 2 seconds, the phase B pulse is turned on to charge the battery; in step S6, after phase B is shut down and waits for 2 seconds, the phase C pulse is turned on to charge the battery.

4. The method for detecting the connection of an electric meter according to any one of claims 1 to 3, characterized in that: In step S3, the specific method for obtaining the first phase with the largest power change is: sorting the absolute values ​​of the first power change of phase A, the first power change of phase B, and the first power change of phase C, and the phase with the largest absolute value is the first phase with the largest power change; in step S5, the specific method for obtaining the second phase with the largest power change is: sorting the absolute values ​​of the second power change of phase A, the second power change of phase B, and the second power change of phase C, and the phase with the largest absolute value is the second phase with the largest power change; in step S7, the specific method for obtaining the third phase with the largest power change is: sorting the absolute values ​​of the third power change of phase A, the third power change of phase B, and the third power change of phase C, and the phase with the largest absolute value is the third phase with the largest power change.

5. The method for detecting the connection of an electric meter according to claim 4, characterized in that: In step S3, the first power variation refers to the difference between the first power of each phase and the corresponding initial power, and the first power of each phase includes: the first power of phase A, the first power of phase B, and the first power of phase C. The first power of phase A, the first power of phase B, and the first power of phase C are respectively subtracted from the corresponding initial power of phase A, the initial power of phase B, and the initial power of phase C to obtain the first power variation of each phase, including the first power variation of phase A, the first power variation of phase B, and the first power variation of phase C; the first power change direction includes forward and reverse; if the first power variation is greater than zero, it indicates forward, and if the first power variation is less than zero, it indicates reverse; In step S5, the second power variation refers to the difference between the second power of each phase and the corresponding initial power, and the second power of each phase includes: the second power of phase A, the second power of phase B, and the second power of phase C. The second power of phase A, the second power of phase B, and the second power of phase C are respectively subtracted from the corresponding initial power of phase A, the initial power of phase B, and the initial power of phase C to obtain the second output power variation of each phase, including the second power variation of phase A, the second power variation of phase B, and the second power variation of phase C; the second power change direction includes forward and reverse; if the second power variation is greater than zero, it indicates forward, and if the second power variation is less than zero, it indicates reverse; In step S7, the third power change refers to the difference between the third power of each phase and the corresponding initial power. The third power of each phase includes: the third power of phase A, the third power of phase B, and the third power of phase C. The third power of phase A, the third power of phase B, and the third power of phase C are subtracted from the corresponding initial power of phase A, the initial power of phase B, and the initial power of phase C respectively to obtain the third power change of each phase, including the third power change of phase A, the third power change of phase B, and the third power change of phase C; the third power change direction includes forward and reverse. If the third power change is greater than zero, it indicates forward; if the third power change is less than zero, it indicates reverse.

6. The method for detecting the connection of an electric meter according to claim 5, characterized in that: In step S8, if phase A is the first phase with the largest power change, when the first power change amount of phase A is greater than zero, it indicates that the change direction of the first phase with the largest power change is forward, indicating that the connection phase sequence and direction of phase A of the three-phase meter are correct; if phase A is the first phase with the largest power change, and the first power change amount of phase A is less than zero, then the change direction of the first phase with the largest power change is reverse, indicating that the connection phase sequence of phase A is correct but the direction is wrong; if phase A is not the first phase with the largest power change, and the change direction of the first phase with the largest power change is not the direction of the first power change amount of phase A, then it indicates that the connection phase sequence and direction of phase A are wrong, and the connection detection of phase A of the three-phase meter is realized; If phase B is the second phase with the largest power change, when the second power change of phase B is greater than zero, the change direction of the second phase with the largest power change is positive, indicating that the phase sequence and direction of the B phase connection are correct; if phase B is the second phase with the largest power change, and the second power change of phase B is less than zero, the change direction of the second phase with the largest power change is reverse, indicating that the phase sequence of the B phase connection is correct but the direction is wrong; if phase B is not the second phase with the largest power change, and the change direction of the second phase with the largest power change is not the direction of the second power change of phase B, it means that the phase sequence and direction of the B phase connection are wrong, thus realizing the detection of the B phase connection of the three-phase meter; If phase C is the third phase with the largest power change, when the third power change amount of phase C is greater than zero, the change direction of the third phase with the largest power change is positive, indicating that the phase sequence and direction of the C phase wiring are correct; if phase C is the third phase with the largest power change, and the third power change amount of phase C is less than zero, the change direction of the third phase with the largest power change is reverse, indicating that the phase sequence of the C phase wiring is correct but the direction is wrong; if phase C is not the third phase with the largest power change, and the change direction of the third phase with the largest power change is not the direction of the third power change amount of phase C, it means that the phase sequence and direction of the C phase wiring are wrong, thereby realizing the C phase wiring detection of the three-phase electric meter.

7. A three-phase inverter system, using the meter connection detection method according to claim 1 or 6 to detect the connection status of a three-phase meter in the system, wherein the three-phase inverter is a three-phase photovoltaic grid-connected inverter or a three-phase energy storage inverter; characterized in that: One end of the three-phase photovoltaic inverter is connected to the photovoltaic array, one end of the three-phase energy storage inverter is connected to the photovoltaic array and the battery respectively, the other end of the three-phase photovoltaic grid-connected inverter or the three-phase energy storage inverter is connected to one end of the three-phase electric meter and the load respectively, and the other end of the three-phase electric meter is connected to the grid.

8. The three-phase inverter system according to claim 7, characterized in that: The three-phase inverter is a three-phase four-wire structure: including phase A, phase B, phase C, and N line, and the N line is a ground line.

9. The three-phase inverter system according to claim 8, characterized in that: The electric meter detection system also includes a register, which is used to store the first maximum power change phase, the second maximum power change phase, the third maximum power change phase, the change direction of the first maximum power change phase, the change direction of the second maximum power change phase, and the change direction of the third maximum power change phase.

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