Grid-connected system and wiring detection method thereof

Abstract

The invention discloses a grid-connected system and a wiring detection method thereof, the grid-connected system comprises a power conversion device and an electric meter, the power conversion device is in communication connection with the electric meter, and the power conversion device is connected to the electric meter through at least three phase ends so as to be connected to a power grid; the wiring detection method comprises the steps of obtaining an initial reactive power value of each phase sequence of the ammeter after determining that the power conversion device and the ammeter work normally, and entering a detection state; controlling one phase end of the power conversion device to output preset reactive power; obtaining a reactive power value of each phase sequence of the ammeter; according to the initial reactive power value, the preset reactive power and the reactive power value, determining the wiring phase sequence and the wiring direction of the current phase end wiring to the electric meter; and entering the next detection period until the wiring phase sequence and the wiring direction of all the phase ends are obtained, and ending the detection state. According to the application, the grid-connected system can be ensured to execute the corresponding control process according to the correct ammeter data, and the occurrence of error control is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of power grid connection, and in particular to a grid connection system and a wiring detection method thereof. Background Art

[0002] At present, the grid-connected system is widely used. Through the grid-connected system, switching between mains power supply and energy storage power supply can be achieved, thereby meeting the demand for uninterrupted power supply.

[0003] In a grid-connected system, in order to collect relevant parameters of the power grid and control power, it is usually necessary to connect an electric meter between the power conversion device and the power grid. The electric meter can collect information such as the voltage, current, active power, and reactive power of the power grid. However, during the installation process, due to the different wiring directions and sequences of the electric meter, the read electric meter data cannot correspond to the phase sequence of the power conversion device, resulting in errors in the power conversion device's collection of grid parameters and power control. Summary of the invention

[0004] In view of this, the present application provides a grid-connected system and a wiring detection method thereof, which detects the wiring phase sequence and wiring direction of the phase end of the power conversion device corresponding to the electric meter, so that the grid-connected system can use the wiring phase sequence and wiring direction to adjust the data correspondence between the power conversion device and the electric meter, so as to ensure that the grid-connected system can execute the corresponding control process according to the correct electric meter data to avoid the occurrence of miscontrol. The technical solution of the present application is as follows: The first aspect of the present application provides a wiring detection method for a grid-connected system, wherein the grid-connected system includes a power conversion device and an electric meter, wherein the power conversion device is communicatively connected to the electric meter, and the power conversion device is connected to the electric meter through at least three phase terminals to connect to a power grid; the wiring detection method includes: after determining that the power conversion device and the electric meter are operating normally, obtaining the initial reactive power value of each phase sequence of the electric meter, and entering a detection state; in a current detection cycle, controlling one of the phase terminals of the power conversion device to output a preset reactive power; obtaining the reactive power value of each phase sequence of the electric meter; determining the wiring phase sequence and wiring direction of the current phase terminal to the electric meter based on the initial reactive power value, the preset reactive power and the reactive power value; entering the next detection cycle until the wiring phase sequence and the wiring direction of all the phase terminals are obtained, and ending the detection state.

[0005] In one embodiment of the present application, the wiring phase sequence and wiring direction of the current phase terminal connection to the electric meter are determined based on the initial reactive power value, the preset reactive power and the reactive power value, including: using the reactive power value and the initial reactive power value to make a difference to obtain the reactive variable of each phase sequence of the electric meter; determining the phase sequence corresponding to the reactive variable matching the preset reactive power as the wiring phase sequence; determining the wiring direction based on the reactive variable corresponding to the wiring phase sequence and the preset reactive power.

[0006] In one embodiment of the present application, determining that the phase sequence corresponding to the reactive variable matching the preset reactive power is the wiring phase sequence includes: obtaining the first absolute value of the preset reactive power; obtaining the second absolute value of the reactive variable of each phase sequence; obtaining the difference between the first absolute value and each of the second absolute values; and determining that the phase sequence corresponding to the difference less than the first preset value is the wiring phase sequence.

[0007] In one embodiment of the present application, the wiring direction is determined based on the reactive variable corresponding to the wiring phase sequence and the preset reactive power, including: when it is determined that the preset reactive power and the reactive variable corresponding to the wiring phase sequence have the same sign, determining that the wiring direction is forward connection; when it is determined that the preset reactive power and the reactive variable corresponding to the wiring phase sequence have opposite signs, determining that the wiring direction is reverse connection.

[0008] In an embodiment of the present application, it also includes: when it is determined that there are multiple or zero reactive variables that match the preset reactive power, determining that the grid-connected system has a wiring fault.

[0009] In an embodiment of the present application, it further includes: when it is determined that the difference is greater than a second preset value, determining that the grid-connected system has a wiring fault, and the second preset value is greater than the first absolute value.

[0010] In one embodiment of the present application, controlling one of the phase ends of the power conversion device to output a preset reactive power includes: controlling one of the phase ends of the power conversion device to output a preset reactive power, and controlling the reactive power output by the remaining phase ends to remain unchanged.

[0011] In one embodiment of the present application, after determining that the power conversion device and the electric meter are working normally, the initial reactive power value of each phase sequence of the electric meter is obtained, and a detection state is entered, including: reading the meter data of the electric meter, and determining whether the electric meter is working normally according to the meter data; collecting the first grid voltage of the power grid, and collecting the second grid voltage at the grid end of the electric meter, and determining whether the grid-connected system is connected normally according to the first grid voltage and the second grid voltage; when it is determined that the power conversion device and the electric meter are working normally, and the grid-connected system is connected normally, the detection state is entered.

[0012] The second aspect of the present application provides a grid-connected system, including a power conversion device and an electric meter, wherein the power conversion device is communicatively connected to the electric meter, and the power conversion device is connected to the electric meter through at least three phase terminals to connect to the power grid; the power conversion device includes a controller; the controller is used to obtain the initial reactive power value of each phase sequence of the electric meter after determining that the power conversion device and the electric meter are operating normally, control the phase terminal of the power conversion device to output a preset reactive power, so as to obtain the reactive power value of each phase sequence of the electric meter, and detect the wiring phase sequence and wiring direction of all the phase terminals.

[0013] In one embodiment of the present application, the controller is used to obtain the initial reactive power value of each phase sequence of the electric meter after determining that the power conversion device and the electric meter are operating normally, and enter a detection state. In the current detection cycle, the controller controls one of the phase ends of the power conversion device to output a preset reactive power, obtains the reactive power value of each phase sequence of the electric meter, and determines the connection phase sequence and connection direction of the current phase end to the electric meter based on the initial reactive power value, the preset reactive power and the reactive power value, and enters the next detection cycle until the connection phase sequence and the connection direction of all the phase ends are obtained, and the detection state is ended.

[0014] The embodiment of the present application enters a detection state after determining that the power conversion device and the electric meter are operating normally, and controls a single phase end of the power conversion device to output a preset reactive power to the electric meter, thereby disturbing the reactive power value of the phase sequence of the electric meter corresponding to the phase end, and then detects the wiring phase sequence and wiring direction on the electric meter corresponding to the current phase end according to the initial reactive power value of each phase sequence of the electric meter, the reactive power value after disturbance, and the preset reactive power, so that the grid-connected system can use the wiring phase sequence and wiring direction to adjust the data correspondence between the power conversion device and the electric meter, so as to ensure that the grid-connected system can execute the corresponding control process according to the correct electric meter data to avoid the occurrence of miscontrol. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1It is a schematic block diagram of a grid-connected system provided in an embodiment of the present application.

[0016] Figure 2 It is a flow chart of a wiring detection method provided in an embodiment of the present application.

[0017] Figure 3 It is a flow chart of a method for determining the wiring phase sequence and direction provided in an embodiment of the present application.

[0018] Figure 4 It is a flow chart of a method for determining a wiring phase sequence provided in an embodiment of the present application.

[0019] Figure 5 It is a flow chart of a method for determining a wiring direction provided in an embodiment of the present application.

[0020] Figure 6 It is a flowchart of determining the working status of a power conversion device and an electric meter provided in an embodiment of the present application.

[0021] Figure 7 It is a schematic block diagram of a grid-connected system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0022] It should be noted that in the embodiments of the present application, "at least one" refers to one or more, and "more than one" refers to two or more than two. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0023] It should also be noted that the method disclosed in the embodiments of the present application or the method shown in the flowchart includes one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchangeable with each other, and some of the steps can also be deleted.

[0024] At present, the grid-connected system is widely used. Through the grid-connected system, switching between mains power supply and energy storage power supply can be achieved, thereby meeting the demand for uninterrupted power supply.

[0025] In a grid-connected system, in order to collect relevant parameters of the power grid and control power, it is usually necessary to connect an electric meter between the power conversion device and the power grid. The electric meter can collect information such as the voltage, current, active power, and reactive power of the power grid. However, during the installation process, due to the different wiring directions and sequences of the electric meter, the read electric meter data cannot correspond to the phase sequence of the power conversion device, resulting in errors in the power conversion device's collection of grid parameters and power control.

[0026] The embodiment of the present application provides a grid-connected system and a wiring detection method thereof, which are used to detect the wiring phase sequence and wiring direction on the electric meter corresponding to the phase end of the power conversion device, so that the grid-connected system can use the wiring phase sequence and wiring direction to adjust the data correspondence between the power conversion device and the electric meter, so as to ensure that the grid-connected system can execute the corresponding control process according to the correct electric meter data to avoid the occurrence of erroneous control.

[0027] Please refer to Figure 1 , Figure 1 This is a schematic block diagram of a grid-connected system provided in an embodiment of the present application. The grid-connected system 100 includes a power conversion device 110 and an electric meter 120 .

[0028] In the embodiment of the present application, the power conversion device 110 is connected to the electric meter 120 for communication, and the power conversion device 110 is connected to the electric meter 120 through at least three phase terminals to connect to the power grid 101. The phase terminal of the power conversion device 110 is the live wire port. For example, when the power conversion device 110 is a three-phase inverter, the three phase terminals can be the A phase port, the B phase port, and the C phase port, respectively, so as to output the three-phase voltage through the three phase terminals or receive the three-phase voltage from the power grid 101. In addition, the power conversion device 110 also includes a neutral line port for connecting the neutral line.

[0029] Among them, the electric meter 120 may include at least three first terminals and at least three second terminals. When installing the electric meter 120, it can be connected to the phase terminal of the power conversion device 110 through the first terminal and the second terminal is connected to the power grid 101, or it can also be connected to the phase terminal of the power conversion device 110 through the second terminal and the first terminal is connected to the power grid 101.

[0030] In some embodiments, the grid-connected system 100 also includes a photovoltaic energy storage device. In the grid-connected state, the grid-connected system 100 can receive electric energy from the grid 101 to supply power to the load, and the power conversion device 110 can store the electric energy from the grid 101 in the photovoltaic energy storage device. In the off-grid state, the grid-connected system 100 no longer receives electric energy from the grid 101, and the power conversion device 110 obtains electric energy from the photovoltaic energy storage device to supply power to the load.

[0031] Please refer to Figure 2 , Figure 2 A schematic diagram of a wiring detection method provided in an embodiment of the present application specifically includes the following steps: Step S21: After confirming that the power conversion device and the electric meter are working normally, the initial reactive power value of each phase sequence of the electric meter is obtained, and a detection state is entered.

[0032] In the embodiment of the present application, the grid-connected system further includes a controller, wherein the controller may be a control device independent of the power conversion device, or may also be a controller of the power conversion device, which is not limited here. During the operation of the grid-connected system, the controller may detect the working status of the power conversion device and the electric meter in real time, and read the current initial reactive power value of each phase sequence of the electric meter after confirming that the power conversion device and the electric meter are working normally.

[0033] It can be understood that after determining that the power conversion device can work normally, the controller may first not start the power conversion device to output electric energy, and then obtain the initial reactive power value of each phase sequence of the electric meter.

[0034] Step S22: In the current detection cycle, controlling one phase end of the power conversion device to output a preset reactive power.

[0035] In the embodiment of the present application, after entering the detection state, the controller will respectively detect the connection relationship between each phase end of the power conversion device and the phase sequence of the electric meter, that is, detect the connection phase sequence and connection direction of each phase end connected to the electric meter. The controller divides the corresponding number of detection cycles according to the number of phase ends of the power conversion device, and detects the corresponding phase end in each detection cycle.

[0036] Among them, after entering the current detection cycle, the controller first controls one of the phase ends corresponding to the power conversion device to output a preset reactive power to disturb the reactive power value of the corresponding phase sequence in the electric meter, thereby causing the electric meter to generate data that can be used for detection. In some embodiments, one of the phase ends of the power conversion device is controlled to output a preset reactive power, and the reactive power output by the remaining phase ends is controlled to remain unchanged.

[0037] Step S23: Obtain the reactive power value of each phase sequence of the electric meter.

[0038] In the embodiment of the present application, the controller controls one of the phase ends of the power conversion device to output a preset reactive power in the current detection cycle, and can wait for a preset time, and then obtain the reactive power value of each phase sequence of the electric meter after the preset reactive power output is stable. It can be understood that the phase sequence of the electric meter connected to the phase end corresponding to the current detection cycle, after being disturbed by the preset reactive power, will still have a large difference between its corresponding reactive power value and the initial reactive power value.

[0039] Step S24: Determine the wiring phase sequence and wiring direction of the current phase terminal connection to the electric meter according to the initial reactive power value, the preset reactive power and the reactive power value.

[0040] It can be understood that according to the initial reactive power and reactive power value corresponding to each phase sequence, the phase sequence with the largest reactive power disturbance in the electric meter can be obtained as the above-mentioned wiring phase sequence. For example, the controller can calculate the difference between the initial reactive power and the reactive power value corresponding to each phase sequence. The largest difference indicates that the reactive power disturbance is the largest. The controller can also determine the corresponding wiring direction according to the preset reactive power and the reactive power value generated by the electric meter.

[0041] Step S25: Enter the next detection cycle until the connection phase sequence and connection direction of all phase ends are obtained, and the detection state ends.

[0042] In an embodiment of the present application, after obtaining the wiring phase sequence and wiring direction of the phase end corresponding to the power conversion device in the current detection cycle, the controller will enter the next detection cycle to obtain the wiring phase sequence and wiring direction of another phase end until the wiring phase sequence and wiring direction of all phase ends of the power conversion device are obtained. For example, when the power conversion device is a three-phase inverter, the controller can perform the above steps in sequence to obtain the wiring phase sequence and wiring direction of phase A, phase B and phase C connected to the electric meter.

[0043] In some embodiments, after obtaining the wiring phase sequence and wiring direction of the power conversion device connected to the electric meter through the detection in the above steps, the controller can use the wiring phase sequence and wiring direction to adjust the data correspondence between the power conversion device and the electric meter to ensure that the grid-connected system can execute the corresponding control process according to the correct electric meter data to avoid the occurrence of miscontrol.

[0044] It can be understood that the embodiment of the present application enters a detection state after determining that the power conversion device and the electric meter are operating normally, and controls a single phase end of the power conversion device to output a preset reactive power to the electric meter, thereby disturbing the reactive power value of the phase sequence of the electric meter corresponding to the phase end, and then detects the wiring phase sequence and wiring direction on the electric meter corresponding to the current phase end according to the initial reactive power value of each phase sequence of the electric meter, the reactive power value after disturbance, and the preset reactive power, so that the grid-connected system can use the wiring phase sequence and wiring direction to adjust the data correspondence between the power conversion device and the electric meter, so as to ensure that the grid-connected system can execute the corresponding control process according to the correct electric meter data to avoid the occurrence of miscontrol.

[0045] Please refer to Figure 3 , Figure 3 A flow chart of a method for determining a wiring phase sequence and direction provided in an embodiment of the present application specifically includes the following steps: Step S31: subtract the reactive power value from the initial reactive power value to obtain the reactive variable of each phase sequence of the electric meter.

[0046] In the embodiment of the present application, the power conversion device is a three-phase inverter, and the A phase end of the power conversion device is detected in the current detection cycle as an example. The initial reactive power values ​​of the three phase sequences of the meter obtained by the controller are Q L1 , Q L2 and Q L3 , control the A phase end of the power conversion device to output a preset reactive power of Q A The reactive power values ​​of the three phase sequences of the electric meter are L1, L2 and L3 respectively, then L1 and Q L1 Make the difference to get the corresponding reactive variable ΔQ L1 , and so on, the reactive variable ΔQ of each phase sequence of the meter can be obtained L1 , ΔQ L2 and ΔQ L3 .

[0047] Step S32: Determine that the phase sequence corresponding to the reactive variable matching the preset reactive power is the wiring phase sequence.

[0048] It can be understood that in the above example, the preset reactive power output of phase A is controlled to be Q A , thereby disturbing the reactive power value Ln of one of the corresponding phase sequences in the meter, then the reactive power value Ln and the initial reactive power value Q Ln Reactive variable ΔQ Ln With the preset reactive power Q A Therefore, in the above matching process, the controller can obtain the preset reactive power Q A Similar reactive variable ΔQ Ln The corresponding phase sequence is the wiring phase sequence.

[0049] Step S33: Determine the wiring direction according to the reactive variable corresponding to the wiring phase sequence and the preset reactive power.

[0050] In some embodiments, when it is determined that there are multiple or zero reactive variables that match the preset reactive power, a grid-connected system wiring fault is determined. It can be understood that when there are multiple reactive variables that match the preset reactive power, it means that the currently detected phase end may be connected to multiple phase sequences of the electric meter, and when there are zero reactive variables that match the preset reactive power, it means that the currently detected phase end may not be connected to any phase sequence of the electric meter, so there is a wiring fault.

[0051] In some embodiments, please refer to Figure 4 The step S32 for determining the wiring phase sequence may further include the following steps: Step S41: Obtain a first absolute value of a preset reactive power.

[0052] Step S42: Obtain the second absolute value of the reactive variable of each phase sequence.

[0053] Step S43: Obtain the difference between the first absolute value and each second absolute value.

[0054] Step S44: Determine that the phase sequence corresponding to the difference smaller than the first preset value is the wiring phase sequence.

[0055] In the embodiment of the present application, the power conversion device is a three-phase inverter, and the A phase end of the power conversion device is detected in the current detection cycle as an example. The initial reactive power values ​​of the three phase sequences of the meter obtained by the controller are Q L1 , Q L2 and Q L3 , control the A phase end of the power conversion device to output a preset reactive power of Q A The reactive power values ​​of the three phase sequences of the meter obtained are L1, L2 and L3 respectively. If , then ΔQ Ln The corresponding phase sequence is the wiring phase sequence, is the first preset value mentioned above.

[0056] In some embodiments, when it is determined that there is a difference greater than a second preset value, it is determined that the grid-connected system has a wiring fault, and the second preset value is greater than the first absolute value. When the grid-connected system is faulty, it is determined that the grid-connected system wiring is faulty.

[0057] In some embodiments, please refer to Figure 5 The step S33 of determining the wiring direction may further include the following steps: Step S51: When it is determined that the preset reactive power has the same sign as the reactive variable corresponding to the connection phase sequence, it is determined that the connection direction is forward connection.

[0058] Step S52: When it is determined that the preset reactive power has opposite signs to the reactive variable corresponding to the wiring phase sequence, it is determined that the wiring direction is reverse connection.

[0059] For example, the controller determines ΔQ in the above example L1 When the corresponding phase sequence is the wiring phase sequence, if ΔQ L1 With preset reactive power Q A When they are both positive or negative values, the wiring direction is determined to be positive, otherwise it is reverse.

[0060] In some embodiments, please refer to Figure 6 The above step S21 determines the working status of the power conversion device and the electric meter and specifically includes the following steps: Step S61: Read the meter data of the meter, and determine whether the meter is operating normally according to the meter data.

[0061] In the embodiment of the present application, before entering the detection state to perform wiring detection, the controller can determine whether the communication connection with the meter is normal by reading the meter data, and determine whether the meter is working normally based on the meter data.

[0062] Step S62: collecting a first grid voltage of the grid and a second grid voltage of the grid end of the electric meter, and determining whether the grid-connected system is connected normally according to the first grid voltage and the second grid voltage.

[0063] In an embodiment of the present application, a voltage sampling circuit may also be provided in the grid-connected system. The controller collects a first grid voltage of the power grid through the voltage sampling circuit, and obtains a second grid voltage at the grid end of the meter by reading meter data. When it is determined that the first grid voltage matches the second grid voltage, it is determined that the wiring of the grid-connected system is normal.

[0064] Step S63: When it is determined that the power conversion device and the electric meter are operating normally and the grid-connected system is connected normally, the detection state is entered.

[0065] Please refer to Figure 7 , Figure 7 A schematic block diagram of a grid-connected system provided in an embodiment of the present application, wherein the grid-connected system 700 includes a power conversion device 710 and an electric meter 720, the power conversion device 710 is communicatively connected to the electric meter 720, and the power conversion device 710 is connected to the electric meter 720 through at least three phase terminals to connect to a power grid 701. The power conversion device 710 includes a controller 711.

[0066] In an embodiment of the present application, the controller 711 is used to obtain the initial reactive power value of each phase sequence of the electric meter 720 after determining that the power conversion device 710 and the electric meter 720 are operating normally, control the phase end of the power conversion device 710 to output a preset reactive power, so as to obtain the reactive power value of each phase sequence of the electric meter 720, and detect the wiring phase sequence and wiring direction of all phase ends.

[0067] In some embodiments, the controller 711 is used to obtain the initial reactive power value of each phase sequence of the electric meter 720 after determining that the power conversion device 710 and the electric meter 720 are operating normally, and enter a detection state. In the current detection cycle, one phase end of the power conversion device 710 is controlled to output a preset reactive power, and the reactive power value of each phase sequence of the electric meter 720 is obtained. According to the initial reactive power value, the preset reactive power and the reactive power value, the connection phase sequence and connection direction of the current phase end to the electric meter 720 are determined, and the next detection cycle is entered until the connection phase sequence and connection direction of all phase ends are obtained, and the detection state is ended.

[0068] Controlling one phase end of the power conversion device 710 to output a preset reactive power includes: controlling one phase end of the power conversion device 710 to output a preset reactive power, and controlling the reactive powers output by the other phase ends to remain unchanged.

[0069] In some embodiments, the controller 711 is used to obtain the reactive variable of each phase sequence of the electric meter 720 by subtracting the reactive power value from the initial reactive power value, determine the phase sequence corresponding to the reactive variable matching the preset reactive power as the wiring phase sequence, and determine the wiring direction according to the reactive variable corresponding to the wiring phase sequence and the preset reactive power.

[0070] In some embodiments, the controller 711 is used to obtain the first absolute value of a preset reactive power, obtain the second absolute value of the reactive variable of each phase sequence, obtain the difference between the first absolute value and each second absolute value, and determine that the phase sequence corresponding to the difference less than the first preset value is the wiring phase sequence.

[0071] In some embodiments, the controller 711 is used to determine that when the signs of the preset reactive power and the reactive variable corresponding to the wiring phase sequence are the same, the wiring direction is determined to be forward connection; when the signs of the preset reactive power and the reactive variable corresponding to the wiring phase sequence are opposite, the wiring direction is determined to be reverse connection.

[0072] In some embodiments, the controller 711 is configured to determine that a connection fault occurs in the grid-connected system 700 when it is determined that there are multiple or zero reactive variables that match the preset reactive power.

[0073] In some embodiments, the controller 711 is used to determine that there is a connection fault in the grid-connected system 700 when the difference is greater than a second preset value, and the second preset value is greater than the first absolute value.

[0074] In some embodiments, the controller 711 is used to read the meter 720 data of the meter 720, determine whether the meter 720 is operating normally based on the meter 720 data, collect the first grid voltage of the grid 701, and collect the second grid voltage of the grid 701 end of the meter 720, and determine whether the grid-connected system 700 is connected normally based on the first grid voltage and the second grid voltage. When it is determined that the power conversion device 710 and the meter 720 are operating normally and the grid-connected system 700 is connected normally, the detection state is entered.

[0075] It can be understood that the beneficial effects of the grid-connected system 700 of the embodiment of the present application can refer to the beneficial effects of the wiring detection method in the aforementioned embodiment, and will not be repeated here.

[0076] In the embodiment of the present application, a more detailed functional description of each of the above modules can be referred to the corresponding content of the aforementioned part, which will not be repeated here.

[0077] An embodiment of the present application further provides a computer storage medium, which stores a computer program. When the computer program is executed by a processor, the processor executes the above-mentioned wiring detection method.

[0078] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer storage medium or transmitted through the computer storage medium. The computer instructions may be transmitted from a website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a digital versatile disc (DVD)), or a semiconductor medium (eg, a solid state disk (SSD)).

[0079] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other media that can store program codes. In the absence of conflict, the technical features in this embodiment and the implementation scheme can be combined arbitrarily.

[0080] The embodiments described above are merely preferred embodiments of the present application and are not intended to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements made to the technical solutions of the present application by ordinary technicians in this field should fall within the protection scope determined by the claims of the present application.

Claims

1. A wiring detection method for a grid-connected system, characterized in that: The grid-connected system comprises a power conversion device and an electric meter, wherein the power conversion device is communicatively connected to the electric meter, and the power conversion device is connected to the electric meter via at least three phase terminals to be connected to the grid; The wiring detection method comprises: After determining that the power conversion device and the electric meter are working normally, obtaining the initial reactive power value of each phase sequence of the electric meter and entering a detection state; In the current detection cycle, controlling one of the phase ends of the power conversion device to output a preset reactive power; Obtaining reactive power values ​​of each phase sequence of the electric meter; Determine the current connection phase sequence and connection direction of the phase terminal to the electric meter according to the initial reactive power value, the preset reactive power and the reactive power value; Enter the next detection cycle until the connection phase sequence and the connection direction of all the phase ends are obtained, and end the detection state.

2. The wiring detection method according to claim 1, characterized in that: The determining, according to the initial reactive power value, the preset reactive power and the reactive power value, the current wiring phase sequence and wiring direction of the phase terminal connection to the electric meter includes: The reactive power value is subtracted from the initial reactive power value to obtain the reactive variable of each phase sequence of the electric meter; Determine that the phase sequence corresponding to the reactive variable matching the preset reactive power is the wiring phase sequence; The wiring direction is determined according to the reactive variable corresponding to the wiring phase sequence and the preset reactive power.

3. The wiring detection method according to claim 2, characterized in that: The step of determining the phase sequence corresponding to the reactive variable matching the preset reactive power as the wiring phase sequence comprises: Obtaining a first absolute value of the preset reactive power; Acquire the second absolute value of the reactive variable of each phase sequence; Obtaining a difference between the first absolute value and each of the second absolute values; Determine that the phase sequence corresponding to the difference value that is smaller than the first preset value is the wiring phase sequence.

4. The wiring detection method according to claim 2, characterized in that: The determining the wiring direction according to the reactive variable corresponding to the wiring phase sequence and the preset reactive power includes: When it is determined that the preset reactive power has the same sign as the reactive variable corresponding to the connection phase sequence, determining that the connection direction is forward connection; When it is determined that the preset reactive power has opposite signs to the reactive variable corresponding to the wiring phase sequence, it is determined that the wiring direction is reverse connection.

5. The wiring detection method according to claim 2, characterized in that: Also includes: When it is determined that there are multiple or zero reactive variables that match the preset reactive power, it is determined that the grid-connected system has a wiring fault.

6. The wiring detection method according to claim 3, characterized in that: Also includes: When it is determined that the difference is greater than a second preset value, it is determined that there is a connection fault in the grid-connected system, and the second preset value is greater than the first absolute value.

7. The wiring detection method according to claim 1, characterized in that: The step of controlling one of the phase ends of the power conversion device to output a preset reactive power comprises: The power conversion device is controlled to output a preset reactive power at one of the phase ends, and the reactive power outputted by the other phase ends is controlled to remain unchanged.

8. The wiring detection method according to claim 1, characterized in that: After determining that the power conversion device and the electric meter are working normally, obtaining the initial reactive power value of each phase sequence of the electric meter and entering the detection state includes: Reading the meter data of the meter, and determining whether the meter is operating normally according to the meter data; Collecting a first grid voltage of the grid and a second grid voltage of the grid end of the electric meter, and determining whether the grid-connected system is connected normally according to the first grid voltage and the second grid voltage; When it is determined that the power conversion device and the electric meter are operating normally and the grid-connected system is connected normally, the detection state is entered.

9. A grid-connected system, characterized in that: The invention comprises a power conversion device and an electric meter, wherein the power conversion device is communicatively connected to the electric meter, and the power conversion device is connected to the electric meter through at least three phase terminals so as to be connected to a power grid; the power conversion device comprises a controller; The controller is used to obtain the initial reactive power value of each phase sequence of the meter after determining that the power conversion device and the meter are operating normally, control the phase end of the power conversion device to output a preset reactive power, so as to obtain the reactive power value of each phase sequence of the meter, and detect the wiring phase sequence and wiring direction of all the phase ends.

10. The grid-connected system according to claim 9, characterized in that: The controller is used to obtain the initial reactive power value of each phase sequence of the electric meter after determining that the power conversion device and the electric meter are operating normally, and enter a detection state. In the current detection cycle, the controller controls one of the phase ends of the power conversion device to output a preset reactive power, obtains the reactive power value of each phase sequence of the electric meter, determines the wiring phase sequence and wiring direction of the current phase end to the electric meter according to the initial reactive power value, the preset reactive power and the reactive power value, enters the next detection cycle, and ends the detection state until the wiring phase sequence and wiring direction of all the phase ends are obtained.

Images