Ammeter phase sequence adjusting method, sampling device and grid-connected power generation system

Abstract

The invention relates to an ammeter phase sequence adjusting method, a computer readable storage medium, a sampling device and a grid-connected power generation system, after an inverter is connected to a grid, if it is determined that reactive current output by the inverter reaches preset reactive current, reactive current increment of the inverter is calculated, and three-phase instantaneous current of a three-phase power grid is obtained; determining a current sampling phase sequence of the electric meter based on the reactive current increment, obtaining a three-phase voltage of the inverter and performing clark conversion to obtain a first voltage component and a second voltage component, determining a voltage sampling phase sequence of the electric meter according to the first voltage component, the second voltage component and the three-phase instantaneous current, and if the current sampling phase sequence or the voltage sampling phase sequence is incorrect, determining that the three-phase instantaneous current is correct. And exchanging the corresponding relationship between the sampling data corresponding to the incorrect current sampling phase sequence or the incorrect voltage sampling phase sequence and the preset assignment data, so that the current sampling phase sequence and the voltage sampling phase sequence are matched with the phase sequence of the signal output to the three-phase power grid by the inverter. The ammeter calculation correctness is improved, and the phase sequence adjustment efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of electric meters, and in particular to an electric meter phase sequence adjustment method, device, computer-readable storage medium, sampling device, and grid-connected power generation system. Background Art

[0002] An electric meter is an instrument used to measure the electrical energy in a three-phase AC circuit. By sampling the current and voltage in the three-phase circuit, the meter can calculate the total energy consumed in the three-phase circuit. When used for power detection, the meter must match the voltage and current phase sequence—that is, the meter's voltage and current phase sequence must match the inverter's phase sequence—to accurately calculate the power of each of the three phases.

[0003] Traditional methods of adjusting the phase sequence are to adjust the phase sequence of the wiring according to the equipment's wire markings, colors, or using a phase finder. However, these methods consume high labor costs and are inefficient. Summary of the Invention

[0004] Based on this, it is necessary to address the technical problem of low efficiency of traditional phase sequence adjustment methods and provide a phase sequence adjustment method, device, computer-readable storage medium, sampling device and grid-connected power generation system for electric meters that can improve adjustment efficiency.

[0005] In a first aspect, the present application provides a method for adjusting the phase sequence of an electric meter, which is applied to an electric meter, wherein the electric meter is electrically connected to an inverter and a three-phase power grid, respectively, and the inverter is connected to the three-phase power grid. The method includes:

[0006] After the inverter enters the grid-connected state, if it is determined that the reactive current output by the inverter reaches a preset reactive current, calculating the reactive current increment of the inverter and obtaining the three-phase instantaneous current of the three-phase grid;

[0007] determining a current sampling phase sequence of the electric meter based on the reactive current increment;

[0008] Obtaining a three-phase voltage of the inverter, and performing a Clark transformation on the three-phase voltage to obtain a first voltage component and a second voltage component;

[0009] determining a voltage sampling phase sequence of the electric meter according to the first voltage component, the second voltage component, and the three-phase instantaneous current;

[0010] If the current sampling phase sequence or the voltage sampling phase sequence is incorrect, the corresponding sampling data corresponding to the incorrect current sampling phase sequence or voltage sampling phase sequence are swapped with the preset assignment data, so that the current sampling phase sequence and the voltage sampling phase sequence match the phase sequence of the signal output by the inverter to the three-phase power grid.

[0011] In a second aspect, the present application further provides a sampling device, which is applied between an inverter and a three-phase power grid, wherein the sampling device includes an electric meter and a current detection device, wherein the current detection device is connected to the electric meter;

[0012] The current detection device is arranged between the connection line between the inverter and the three-phase power grid, and is used to detect the current on the connection line and send the current data to the electric meter. The electric meter is electrically connected to the connection line between the inverter and the three-phase power grid. The electric meter is used to implement the steps of the method of any of the above embodiments.

[0013] On the third aspect, the present application also provides a grid-connected power generation system, including an inverter, a three-phase power grid and a sampling device as described in the above embodiment, wherein the inverter is electrically connected to the three-phase power grid, and each phase of the inverter is connected one-to-one with each phase of the three-phase power grid.

[0014] In a fourth aspect, the present application further provides an electric meter phase sequence adjustment device, which is applied to an electric meter, wherein the electric meter is electrically connected to an inverter and a three-phase power grid, respectively, and the inverter is connected to the three-phase power grid, and the device comprises:

[0015] a current acquisition module, configured to calculate the reactive current increment of the inverter and obtain the three-phase instantaneous current of the three-phase grid if it is determined that the reactive current output by the inverter reaches a preset reactive current after the inverter enters the grid-connected state;

[0016] a current phase sequence determining module, configured to determine a current sampling phase sequence of the electric meter based on the reactive current increment;

[0017] a voltage acquisition module, configured to acquire the three-phase voltage of the inverter and perform a Clark transformation on the three-phase voltage to obtain a first voltage component and a second voltage component;

[0018] a voltage phase sequence determining module, configured to determine a voltage sampling phase sequence of the electric meter according to the first voltage component, the second voltage component, and the three-phase instantaneous current;

[0019] The phase sequence adjustment module is used to swap the corresponding sampling data corresponding to the incorrect current sampling phase sequence or voltage sampling phase sequence with the preset assignment data if the current sampling phase sequence or the voltage sampling phase sequence is incorrect, so that the current sampling phase sequence and the voltage sampling phase sequence match the phase sequence of the signal output by the inverter to the three-phase power grid.

[0020] In a fifth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the following steps are implemented:

[0021] After the inverter enters the grid-connected state, if it is determined that the reactive current output by the inverter reaches a preset reactive current, calculating the reactive current increment of the inverter and obtaining the three-phase instantaneous current of the three-phase grid;

[0022] determining a current sampling phase sequence of the electric meter based on the reactive current increment;

[0023] Obtaining a three-phase voltage of the inverter, and performing a Clark transformation on the three-phase voltage to obtain a first voltage component and a second voltage component;

[0024] determining a voltage sampling phase sequence of the electric meter according to the first voltage component, the second voltage component, and the three-phase instantaneous current;

[0025] If the current sampling phase sequence or the voltage sampling phase sequence is incorrect, the corresponding sampling data corresponding to the incorrect current sampling phase sequence or voltage sampling phase sequence are swapped with the preset assignment data, so that the current sampling phase sequence and the voltage sampling phase sequence match the phase sequence of the signal output by the inverter to the three-phase power grid.

[0026] The above-mentioned electric meter phase sequence adjustment method, device, computer-readable storage medium, sampling device, and grid-connected power generation system, after the inverter enters the grid-connected state, if it is determined that the reactive current output by the inverter has reached a preset reactive current, the reactive current increment is calculated, and the three-phase instantaneous current is sampled. The current sampling phase sequence of the electric meter is determined based on the reactive current increment, the three-phase voltage of the inverter is obtained, and the three-phase voltage is subjected to a Clark transformation to obtain a first voltage component and a second voltage component. The voltage sampling phase sequence of the electric meter is determined based on the first voltage component, the second voltage component, and the three-phase instantaneous current. If the current sampling phase sequence or the voltage sampling phase sequence is incorrect, the corresponding relationship between the sampling data corresponding to the incorrect current sampling phase sequence or voltage sampling phase sequence and the preset assignment data is swapped, so that the current sampling phase sequence and the voltage sampling phase sequence match the phase sequence of the signal output by the inverter to the three-phase grid. The current and voltage sampling phase sequence of the meter can be accurately identified by sampling current and voltage. If a misconnection occurs, the sampling amount can be adjusted to match the phase sequence of the current and voltage sampling with the inverter phase sequence. This achieves adaptive voltage and current phase sequence in the meter, which helps improve the accuracy of the meter's power calculation. This method also eliminates the need for manual adjustment of the meter's wiring, reducing operation and maintenance costs and improving the efficiency of phase sequence adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments of the present application or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 A diagram showing an application environment of a method for adjusting the phase sequence of an electric meter according to an embodiment;

[0029] Figure 2 1 is a flow chart of a method for adjusting the phase sequence of an electric meter according to an embodiment;

[0030] Figure 3 A schematic flow chart of the steps for calculating reactive current increment in one embodiment;

[0031] Figure 4 1 is a flow chart of steps for determining the current sampling phase sequence of an electric meter based on reactive current increment in another embodiment;

[0032] Figure 5 Schematic diagram of a flow chart of a method for adjusting the phase sequence of an electric meter in another embodiment;

[0033] Figure 6 1. A flow chart illustrating steps for determining the current sampling accuracy of an electric meter according to a reactive current increment and a preset reactive current in one embodiment;

[0034] Figure 7 1 is a flow chart of steps for determining a voltage sampling phase sequence of an electric meter according to a first voltage component, a second voltage component and a three-phase instantaneous current in one embodiment;

[0035] Figure 8 1 is a schematic diagram of a process flow of current sampling phase sequence adaptation in one embodiment;

[0036] Figure 9 1 is a schematic diagram of a process flow for voltage sampling phase sequence adaptation in one embodiment;

[0037] Figure 10 FIG. 4 is a structural block diagram of an electric meter phase sequence adjustment device in one embodiment. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0039] The phase sequence adjustment method of the electric meter provided in the embodiment of the present application can be applied to Figure 1In the application environment shown, it can be specifically applied to an electricity meter. The inverter (i.e., the three-phase energy storage converter in the figure) is connected to the three-phase grid via a connecting line. Specifically, three connecting lines can be used to connect to different phases of the three-phase grid, including phase A, phase B, and phase C. The electricity meter can be connected to the connecting line between the inverter and the three-phase grid via a wire, electrically connected to the inverter and the three-phase grid, and sampling the three-phase voltage on the connecting line. The electricity meter is also connected to the inverter for communication, and the two can exchange data. The electricity meter can also be connected to the three-phase grid for communication, such as detecting the operating parameters of the three-phase grid. For example, the electricity meter and the inverter can exchange data via RS-485, which has strong anti-interference capabilities and high communication quality.

[0040] In addition, a current detection device is installed on the connection line between the inverter and the three-phase grid. This device is used to detect the current in the connection line between the inverter and the three-phase grid and transmit the detected current to the electricity meter. The current detection device can be a current transformer, which can be installed on the connection line between the inverter and the three-phase grid. Furthermore, the current transformer can be a magnetic ring, and the inverter can be a PCS (Power Conversion System, energy storage inverter). The electricity meter can calculate the active power and reactive power on the grid side based on the sampled voltage and current.

[0041] In an exemplary embodiment, Figure 2 As shown, a method for adjusting the phase sequence of an electric meter is provided. Figure 1 The electric meter in FIG. 1 is taken as an example to illustrate the method, which includes the following steps 202 to 210. Among them:

[0042] Step 202 : After the inverter enters the grid-connected state, if it is determined that the reactive current output by the inverter reaches a preset reactive current, the reactive current increment of the inverter is calculated, and the three-phase instantaneous current of the three-phase grid is obtained.

[0043] The inverter entering the grid-connected state refers to the state in which the inverter is connected to the grid and the AC power output by the inverter is connected to the grid through the power line. The preset reactive current is a preset current value, and the specific value can be determined according to actual needs. In this embodiment, the preset reactive current includes three-phase preset reactive currents, namely, phase A preset reactive current I a_pcs_set , B phase preset reactive current I b_pcs_set and phase C preset reactive current I c_pcs_set The three-phase preset reactive currents are different. The magnitudes of the three-phase preset reactive currents can be a set of arithmetic progressions. The relationship between the three-phase preset reactive currents can be:

[0044]

[0045] Among them, Iset_delta The difference between the reactive currents of two adjacent phases is preset.

[0046] After the inverter enters the grid-connected state, it will send the preset reactive current I a_pcs_set、 I b_pcs_set、 I c_pcs_set When the inverter detects that the reactive current output by the inverter reaches the preset reactive current, it can send a command to the meter via RS485 to enable the meter to calculate the reactive current increment of the inverter and enable the meter to sample the three-phase instantaneous current of the three-phase grid. Among them, the three-phase instantaneous current includes the instantaneous current of phase A I a_meter、 Phase B instantaneous current I b_ meter and the instantaneous current of phase C I c_ meter The reactive current increment represents the difference between the effective value of the grid current at the current sampling moment and the initial value.

[0047] Step 204: Determine the current sampling phase sequence of the electric meter based on the reactive current increment.

[0048] An electric meter can detect three-phase currents individually using a current detection device. Once the current detection device is fixed in place, if the current sampling phase sequence matches the preset current sampling phase sequence and is correct, the current detected by the current detection device will have a theoretical value. The order in which each phase voltage in a three-phase power supply passes through the same value (e.g., its maximum positive value) is called the phase sequence.

[0049] After obtaining the reactive current increment, the three-phase current changes can be determined based on the magnitude of the reactive current increment. By analyzing the actual magnitude of the reactive current increment, for example by referencing the theoretical value of the current under the correct current sampling phase sequence, it is possible to determine whether the meter's current sampling phase sequence conforms to the preset current sampling phase sequence. Furthermore, by analyzing the reactive current increment, it is also possible to determine the incorrect connection mode if the current sampling phase sequence is incorrect.

[0050] Step 206 : Acquire the three-phase voltage of the inverter, and perform Clark transformation on the three-phase voltage to obtain a first voltage component and a second voltage component.

[0051] Among them, the three-phase voltage refers to the three-phase voltage on the connection line between the inverter and the grid collected by the meter, including the A phase voltage V a , B phase voltage V b and C phase voltage V c .

[0052] Afterwards, the three-phase voltage is subjected to a Clark transformation to obtain a first voltage component and a second voltage component. Clark transformation refers to converting the time domain components of a three-phase system (in the abc coordinate system) into two components in an orthogonal stationary coordinate system (αβ) through coordinate transformation. For example, the transformation method can be:

[0053]

[0054] Among them, V alfa_meter is the first voltage component, V beta_meter is the second voltage component.

[0055] Step 208: Determine the voltage sampling phase sequence of the electric meter according to the first voltage component, the second voltage component and the three-phase instantaneous current.

[0056] Assuming the connection between the inverter and the grid is established, and if the voltage sampling phase sequence is correct, the first and second voltage components and the three-phase instantaneous current have theoretical values. When the reactive current generated by the inverter is capacitive, the voltage lags the current by 90 degrees. When the reactive current generated by the inverter is inductive, the voltage leads the current by 90 degrees. Therefore, the voltage sampling phase sequence of the meter can be determined based on the difference between the actual and theoretical values ​​of the first and second voltage components and the three-phase instantaneous current.

[0057] Furthermore, by analyzing the first voltage component, the second voltage component and the three-phase instantaneous current, it is also possible to determine the wrong connection mode when the voltage sampling phase sequence is incorrect.

[0058] In step 210, if the current sampling phase sequence or the voltage sampling phase sequence is incorrect, the sampling data corresponding to the incorrect current sampling phase sequence or the voltage sampling phase sequence is swapped with the corresponding relationship between the preset assignment data so that the current sampling phase sequence and the voltage sampling phase sequence match the phase sequence of the signal output by the inverter to the three-phase grid.

[0059] If either the current sampling phase sequence or the voltage sampling phase sequence is incorrect, or if both the current sampling phase sequence and the voltage sampling phase sequence are incorrect, the phase sequence can be adjusted. Specifically, the adjustment method can be to swap the sampling quantities so that the current sampling phase sequence and the voltage sampling phase sequence match the phase sequence of the signal output by the inverter to the three-phase grid.

[0060] For example, if the current sampling phase sequence is incorrect, the specific misconnection method of the incorrect current sampling phase sequence can be determined, and then the sampling amount is adjusted based on the determined misconnection method so that the current sampling phase sequence corresponding to the adjusted sampling amount matches the phase sequence of the current signal output by the inverter to the three-phase grid. If the voltage sampling phase sequence is incorrect, the specific misconnection method of the incorrect voltage sampling phase sequence can be determined, and then the sampling amount is adjusted based on the determined misconnection method so that the voltage sampling phase sequence corresponding to the adjusted sampling amount matches the phase sequence of the voltage signal output by the inverter to the three-phase grid.

[0061] Swapping the sampling amount can be understood as swapping the corresponding relationship between the sampling data corresponding to the incorrect current sampling phase sequence or voltage sampling phase sequence and the preset value assignment data.

[0062] The sampled data may include data collected by the meter, such as voltage data such as three-phase voltage collected by the meter, or current data such as three-phase instantaneous current collected by a current detection device. The sampled data may also include other data calculated by the meter based on the collected data, such as a first voltage component and a second voltage component.

[0063] Assigned data refers to the data that the meter assigns to sampled data, and preset assigned data refers to the data that the meter assigns to sampled data under preset rules. For example, if the sampled data is a first sampled current from a first current detection device, the meter may set the preset assigned data corresponding to the first sampled current to be the first phase current Cur1; if the sampled data is a second sampled current from a second current detection device, the meter may set the preset assigned data corresponding to the second sampled current to be the second phase current Cur2; and if the sampled data is a third sampled current from a third current detection device, the meter may set the preset assigned data corresponding to the third sampled current to be the third phase current Cur3.

[0064] Swapping the correspondence between the sampling data and the assignment data corresponding to the incorrect current sampling phase sequence or voltage sampling phase sequence means retrieving the sampling data and the assignment data corresponding to the incorrect current sampling phase sequence or voltage sampling phase sequence, and then swapping the original correspondence between the first sampling data and the first assignment data, and the second sampling data and the second assignment data, so that the first sampling data corresponds to the second assignment data, and the second sampling data corresponds to the first assignment data. For example, if the current sampling phase sequence of the first phase current and the second phase current is incorrect, the meter sets the assignment data corresponding to the first sampling current to the second phase current Cur2, and sets the assignment data corresponding to the second sampling current to the first phase current Cur1.

[0065] In the above-mentioned electricity meter phase sequence adjustment method, after the inverter enters the grid-connected state, if it is determined that the reactive current output by the inverter has reached a preset reactive current, the reactive current increment is calculated, and the three-phase instantaneous current is sampled. The current sampling phase sequence of the electricity meter is determined based on the reactive current increment. The three-phase voltage is sampled and a Clark transform is performed on the three-phase voltage to obtain a first voltage component and a second voltage component. The voltage sampling phase sequence of the electricity meter is determined based on the first voltage component, the second voltage component, and the three-phase instantaneous current. If the current sampling phase sequence or the voltage sampling phase sequence is incorrect, the corresponding relationship between the sampled data and the assigned data corresponding to the incorrect current sampling phase sequence or voltage sampling phase sequence is swapped to ensure that the current sampling phase sequence and the voltage sampling phase sequence match the phase sequence of the signal output by the inverter to the three-phase grid. The current and voltage sampling phase sequences of the electricity meter can be accurately identified by the sampled current and voltage. After misconnection, the sampling amount is adjusted to ensure that the current sampling phase sequence and the voltage sampling phase sequence match the phase sequence of the inverter, achieving adaptive voltage and current phase sequence of the electricity meter, which is beneficial for improving the accuracy of the electricity meter power calculation. Moreover, this method does not require manual adjustment of the meter wiring, which can reduce operation and maintenance costs and improve the efficiency of phase sequence adjustment.

[0066] In an exemplary embodiment, Figure 3 As shown, in step 202, after the inverter enters the grid-connected state, if it is determined that the reactive current output by the inverter reaches the preset reactive current, the step of calculating the reactive current increment includes steps 302 to 304. Among them:

[0067] Step 302 : After the inverter enters the grid-connected state, if it is determined that the reactive current output by the inverter reaches a preset reactive current, the effective value of the three-phase grid current and the initial value of the three-phase grid current are obtained.

[0068] Step 304 : Calculate the reactive current increment based on the effective value of the three-phase grid current and the initial value of the three-phase grid current.

[0069] After the inverter enters the grid-connected state, it monitors its own output current. When it detects that the reactive current output by the inverter reaches the preset reactive current, the inverter can send a command to the meter to enable the meter to calculate the reactive current increment.

[0070] Specifically, when the meter receives a command from the inverter, indicating that the reactive current output by the inverter itself reaches a preset reactive current, it samples the effective value of the three-phase grid current, and then calculates the difference between the effective value of the three-phase grid current and the initial value of the three-phase grid current to obtain the reactive current increment. The initial value of the three-phase grid current can be a default value. The reactive current increment includes the reactive current increment of the first phase I a_meter_delta , the second phase reactive current increment I b_meter_delta and the third phase reactive current increment I c_meter_delta。

[0071] For example, when the reactive current output by the inverter reaches the preset reactive current, the effective value of the three-phase grid current includes the effective value of the A-phase grid current I a_meter_new , the effective value of the B phase grid current I b_meter_new and the effective value of the C-phase grid current I c_meter_new The initial value of the three-phase grid current includes the initial value of the A-phase grid current I a_meter_old , the initial value of the B phase grid current I b_meter_old and the initial value of the C phase grid current I c_meter_old , then the calculation method of reactive current increment is:

[0072]

[0073] In this embodiment, after the inverter enters the grid-connected state, if it is determined that the reactive current output by the inverter has reached a preset reactive current, the effective value of the three-phase grid current is sampled, and then the reactive current increment is calculated based on the effective value of the three-phase grid current and the initial value of the three-phase grid current. This allows accurate calculation of the reactive current increment from the initial state to the stage where the reactive current output by the inverter reaches the preset reactive current, which helps improve the accuracy of current sampling phase sequence determination.

[0074] In an exemplary embodiment, the method for adjusting the phase sequence of an electric meter further includes the step of: obtaining, in response to a phase sequence adjustment instruction, an effective value of the current three-phase grid current as an initial value of the three-phase grid current.

[0075] The phase sequence adjustment instruction is issued by the inverter during the self-test phase.

[0076] Before the inverter is connected to the grid, during the self-test phase, it can send a phase sequence adjustment command to the meter via RS485 to enable the meter to start the automatic phase sequence adjustment function. After receiving the phase sequence adjustment command, the meter will obtain the current effective value of the three-phase grid current as the initial value of the three-phase grid current. The effective value of the three-phase grid current after receiving the phase sequence adjustment command can include the effective value of the A-phase grid current, the effective value of the B-phase grid current, and the effective value of the C-phase grid current. The current effective value of the A-phase grid current is used as the initial value of the A-phase grid current. a_meter_old The effective value of the current phase B grid current is used as the initial value of the phase B grid current I b_meter_old The effective value of the current phase C grid current is taken as the initial value of the phase C grid current I c_meter_old .

[0077] In this embodiment, in response to the phase sequence adjustment instruction, the effective value of the current three-phase grid current is obtained as the initial value of the three-phase grid current. Using the effective value of the three-phase grid current sampled during the self-test phase as the initial value of the three-phase grid current can obtain a true and accurate initial value of the three-phase grid current, eliminating the influence of other factors on the initial value of the three-phase grid current, thereby facilitating the improvement of the accuracy of the reactive current increment calculated based on the initial value of the three-phase grid current.

[0078] In an exemplary embodiment, the reactive current increment includes a first-phase reactive current increment, a second-phase reactive current increment, and a third-phase reactive current increment, such as Figure 4 As shown, step 204 includes steps 402 to 404. Among them:

[0079] Step 402 : determining a minimum reactive current increment, an intermediate reactive current increment, and a maximum reactive current increment according to the first-phase reactive current increment, the second-phase reactive current increment, and the third-phase reactive current increment.

[0080] The reactive current increment includes the first phase reactive current increment I a_meter_delta , the second phase reactive current increment I b_meter_delta and the third phase reactive current increment I c_meter_delta。

[0081] The minimum reactive current increment is the minimum value among the first-phase reactive current increment, the second-phase reactive current increment, and the third-phase reactive current increment; the intermediate reactive current increment is the intermediate value among the first-phase reactive current increment, the second-phase reactive current increment, and the third-phase reactive current increment; and the maximum reactive current increment is the maximum value among the first-phase reactive current increment, the second-phase reactive current increment, and the third-phase reactive current increment.

[0082] For example, the minimum reactive current increment I min , intermediate reactive current increment I mid and the maximum reactive current increment I max The method of determining is:

[0083]

[0084] Step 404 : Determine the current sampling phase sequence of the meter based on the magnitude relationship between the first phase reactive current increment and the minimum reactive current increment, the magnitude relationship between the second phase reactive current increment and the intermediate reactive current increment, and the magnitude relationship between the third phase reactive current increment and the maximum reactive current increment.

[0085] Based on the connection relationship established between the electric meter, inverter, and other devices, and assuming that the electric meter's current sampling phase sequence conforms to a preset current sampling phase sequence, the magnitude relationships between the first-phase reactive current increment, the second-phase reactive current increment, and the third-phase reactive current increment and the minimum reactive current increment, the intermediate reactive current increment, and the maximum reactive current increment are determined. Therefore, the electric meter's current sampling phase sequence can be determined based on the magnitude relationships between the first-phase reactive current increment and the minimum reactive current increment, the second-phase reactive current increment and the intermediate reactive current increment, and the third-phase reactive current increment and the maximum reactive current increment, and whether the electric meter's current sampling phase sequence conforms to the preset current sampling phase sequence can be determined.

[0086] In an exemplary embodiment, step 404 includes the steps of: if the first phase reactive current increment is equal to the minimum reactive current increment, the second phase reactive current increment is equal to the intermediate reactive current increment, and the third phase reactive current increment is equal to the maximum reactive current increment, determining that the current sampling phase sequence of the electric meter is correct.

[0087] Among them, the first phase reactive current increment can be understood as the reactive current increment of phase A, the second phase reactive current increment can be understood as the reactive current increment of phase B, and the third phase reactive current increment can be understood as the reactive current increment of phase C. Under the condition that the current sampling phase sequence is correct, taking the current detection device including the first current transformer CT1, the second current transformer CT2 and the third current transformer CT3 as an example, the first current transformer CT1 is set at the phase A of the power grid, the second current transformer CT2 is set at the phase B of the power grid, and the third current transformer CT3 is set at the phase C of the power grid, then the first phase reactive current increment I a_meter_delta Equal to the minimum reactive current increment I min , the second phase reactive current increment I b_meter_delta Equal to the intermediate reactive current increment I mid , the third phase reactive current increment I c_meter_delta Equal to the maximum reactive current increment I max .

[0088] However, if the first phase reactive current increment I a_meter_delta Equal to the minimum reactive current increment I min , the second phase reactive current increment I b_meter_delta Equal to the maximum reactive current increment I max , the third phase reactive current increment I c_meter_delta Equal to the intermediate reactive current increment I mid , indicating that CT1 is connected to phase A of the grid, CT2 is connected to phase C of the grid, and CT3 is connected to phase B of the grid. This indicates that there is an error in the connection relationship between current transformers CT2 and CT3, and the current sampling phase sequence of the meter is incorrect.

[0089] In this case, the sampling amount can be swapped, the current sampling amount of the current transformer CT2 can be set to the third phase current Cur3, the current sampling amount of the current transformer CT3 can be set to the second phase current Cur2, the reactive current increment can be recalculated, and then the meter current sampling phase sequence and the CT connection phase sequence can be re-determined. In this way, the phase sequence adaptation of the meter current is completed.

[0090] In this embodiment, the reactive current increment includes the first-phase reactive current increment, the second-phase reactive current increment, and the third-phase reactive current increment. The minimum reactive current increment, the intermediate reactive current increment, and the maximum reactive current increment are determined based on the first-phase reactive current increment, the second-phase reactive current increment, and the third-phase reactive current increment. The current sampling phase sequence of the meter is determined based on the magnitude relationship between the first-phase reactive current increment and the minimum reactive current increment, the magnitude relationship between the second-phase reactive current increment and the intermediate reactive current increment, and the magnitude relationship between the third-phase reactive current increment and the maximum reactive current increment. This not only accurately determines whether the current sampling phase sequence is correct, but also, if the current sampling phase sequence is incorrect, identifies the misconnection method, facilitating subsequent adjustment of the sampling amount and completing current phase sequence adaptation.

[0091] In an exemplary embodiment, Figure 5 As shown, after step 202, the phase sequence adjustment method of the electric meter further includes step 504: determining whether the current sampling accuracy of the electric meter meets the preset sampling accuracy requirement condition according to the reactive current increment and the preset reactive current.

[0092] It is understood that the reactive current increment should be equal to or close to the preset reactive current, indicating that the current sampling accuracy of the meter can meet the preset sampling accuracy requirements. If the reactive current increment differs significantly from the preset reactive current, the meter may not be able to detect a valid current and thus cannot obtain a valid reactive current increment. In this case, the current sampling accuracy of the meter does not meet the preset sampling accuracy requirements.

[0093] In this embodiment, the current sampling accuracy of the electric meter is determined based on the reactive current increment and the preset reactive current. Therefore, the current sampling accuracy of the electric meter can be judged by comparing the two currents to determine whether it meets the requirements. The judgment process is simple and easy to implement.

[0094] In an exemplary embodiment, Figure 6 As shown, step 504 includes step 604 and step 606.

[0095] Step 604: Determine a reactive current range according to a preset adjustment coefficient and a preset reactive current.

[0096] The preset adjustment coefficient is a fixed value that is used to adjust the magnitude of the preset reactive current, thereby determining the reactive current range. The number and value of the preset adjustment coefficients are not unique. The preset adjustment coefficients include a first preset adjustment coefficient and a second preset adjustment coefficient. The first preset adjustment coefficient is smaller than the second preset adjustment coefficient. The first preset adjustment coefficient and the second preset adjustment coefficient can determine a reactive current range that includes the preset reactive current. The lower limit of the reactive current range is the product of the first preset adjustment coefficient and the preset reactive current, and the upper limit of the reactive current range is the product of the second preset adjustment coefficient and the preset reactive current.

[0097] For example, the first preset adjustment coefficient is 0.8, the second preset adjustment coefficient is 1.2, and the preset reactive current includes three-phase preset reactive currents, namely, the A-phase preset reactive current I a_pcs_set , B phase preset reactive current I b_pcs_set and phase C preset reactive current I c_pcs_set , the reactive current range includes the reactive current range of phase A [I min_pcs_a , I max_pcs_a ]、B phase reactive current range [I min_pcs_b , I max_pcs_b ] and C phase reactive current range [I min_pcs_c , I max_pcs_c ]. The reactive current range can be determined by:

[0098]

[0099] Wherein, K1 is the first preset adjustment coefficient, K2 is the second preset adjustment coefficient, I a_pcs_set Preset reactive current for phase A, I b_pcs_set Preset reactive current for phase B, I c_pcs_set Preset reactive current for phase C.

[0100] Step 606 : judging whether the current sampling accuracy of the electric meter meets a preset sampling accuracy requirement condition according to the reactive current increment and the reactive current range.

[0101] When the reactive current increment and the reactive current range satisfy the following inequality, it means that the current sampling accuracy of the meter meets the preset sampling accuracy requirement. Otherwise, it means that the current sampling accuracy of the meter is insufficient and does not meet the preset sampling accuracy requirement. The comparison relationship is as follows:

[0102]

[0103] Among them, I min is the minimum reactive current increment, I mid is the intermediate reactive current increment, I max is the maximum reactive current increment.

[0104] In this embodiment, the reactive current range is determined based on a preset adjustment coefficient and a preset reactive current, and the current sampling accuracy of the electric meter is determined based on the reactive current increment and the reactive current range. Thus, the electric meter phase sequence adjustment method can also determine the current sampling accuracy of the electric meter, enriching the functionality of the electric meter phase sequence adjustment method and broadening its scope of application.

[0105] In an exemplary embodiment, Figure 7 As shown, step 208 includes step 708 and step 710. Among them:

[0106] Step 708: Determine a connection mode according to the phase of the first voltage component and the second voltage component.

[0107] The first voltage component and the second voltage component are obtained by performing Clark transformation on the three-phase voltage. The first voltage component is V alfa_meter , the second voltage component is V beta_meter .

[0108] Based on the phases of the first and second voltage components, the connection method can be determined, including positive-sequence connection and negative-sequence connection. Positive-sequence connection and negative-sequence connection refer to the phase sequence relationship of three-phase AC power in the power system. Positive sequence refers to the phase difference of each phase voltage in three-phase AC power by 120 degrees and arranged in a certain order. In positive sequence, the voltage of phase A leads the voltage of phase B by 120 degrees, and the voltage of phase B leads the voltage of phase C by 120 degrees. Negative-sequence connection refers to the phase difference of each phase voltage in three-phase AC power by 120 degrees, but in the opposite direction of the positive sequence. In negative sequence, the voltage of phase A lags the voltage of phase B by 120 degrees, and the voltage of phase B lags the voltage of phase C by 120 degrees.

[0109] For example, if the second voltage component lags the first voltage component by 90°, the connection mode may be determined to be a positive sequence connection. If the second voltage component leads the first voltage component by 90°, the connection mode may be determined to be a negative sequence connection.

[0110] Step 710: Based on the determined connection mode, the voltage sampling phase sequence of the electric meter is determined according to the first voltage component and the three-phase instantaneous current.

[0111] The three-phase instantaneous current includes the instantaneous current of phase A I a_meter、 Phase B instantaneous current I b_ meter and the instantaneous current of phase C I c_ meter After the connection mode is determined, the voltage sampling phase sequence of the electric meter can be determined based on the comparison results of the first voltage component and the three-phase instantaneous current.

[0112] Then, step 710 includes the following steps:

[0113] When the connection mode is determined to be positive sequence connection:

[0114] If the phase of the first voltage component lags the phase of the instantaneous current of phase A by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the phase A voltage, the second sampled voltage data corresponds to the phase B voltage, and the third sampled data corresponds to the phase C voltage; or;

[0115] If the phase of the first voltage component lags the phase of the instantaneous current of phase B by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the voltage of phase B, the second sampled voltage data corresponds to the voltage of phase C, and the third sampled data corresponds to the voltage of phase A; or;

[0116] If the phase of the first voltage component lags the phase of the instantaneous current of phase C by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the phase C voltage, the second sampled voltage data corresponds to the phase A voltage, and the third sampled data corresponds to the phase B voltage; or;

[0117] When the connection mode is determined to be negative sequence connection:

[0118] If the phase of the first voltage component lags the phase of the instantaneous current of phase A by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the phase A voltage, the second sampled voltage data corresponds to the phase C voltage, and the third sampled data corresponds to the phase B voltage; or;

[0119] If the phase of the first voltage component lags the phase of the instantaneous current of phase B by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the voltage of phase B, the second sampled voltage data corresponds to the voltage of phase A, and the third sampled data corresponds to the voltage of phase C; or;

[0120] If the phase of the first voltage component lags the phase of the instantaneous current of phase C by 90°, the voltage sampling phase sequence of the meter is determined as follows: the first sampled voltage data corresponds to the phase C voltage, the second sampled voltage data corresponds to the phase B voltage, and the third sampled data corresponds to the phase A voltage. Or;

[0121] For example, the grid voltage is set to V a_grid ,V b_grid ,V c_grid , the first voltage sampling data of the electric meter is Volt1, the second voltage sampling data of the electric meter is Volt2, and the third voltage sampling data of the electric meter is Volt3. Figure 1 The structure of phase A voltage V a_grid The phase lag of the instantaneous current of phase A is I a_meter The phase is 90°; the B phase voltage V b_grid The phase lag of the instantaneous current of phase B I b_meter The phase is 90°; the C phase voltage V c_gridThe phase lag of the instantaneous current of phase C I c_meter The phase is 90°. According to the first voltage component V alfa_meter and the second voltage component V beta_meter Based on the relationship between the voltage and the meter, we can conclude whether the connection mode between the meter and the grid voltage is positive sequence connection or negative sequence connection. There are three cases under positive sequence connection and three cases under negative sequence connection, for a total of six cases:

[0122] Case 1: Volt1 connected to V a_grid , Volt2 connects to V b_grid , Volt3 connected to V c_grid This is the correct connection method. It is a positive sequence connection, with V beta_meter Hysteresis V alfa_meter 90°, V alfa_meter Size, phase and V a_grid same.

[0123] Case 2: Volt1 connected to V a_grid , Volt3 connected to V b_grid , Volt2 connects to V c_grid This is an incorrect connection method. It is a negative sequence connection, and the phase V beta_meter Advanced V alfa_meter 90°, V alfa_meter Size, phase and V a_grid same.

[0124] Case 3: Volt1 connected to V b_grid , Volt2 connects to V c_grid , Volt3 connected to V a_grid This is an incorrect connection method. It is a positive sequence connection, and the phase V beta_meter Hysteresis V alfa_meter 90°, V alfa_meter Size, phase and V b_grid same.

[0125] Case 4: Volt1 connected to V b_grid , Volt2 connects to V a_grid , Volt3 connected to V c_grid This is an incorrect connection method and is also a negative sequence connection. beta_meter Advanced V alfa_meter 90°. V alfa_meter Size, phase and V b_grid same.

[0126] Case 5: Volt1 connected to V c_grid , Volt2 connects to V a_grid , Volt3 connected to V b_gridThis is an incorrect connection method, which is also a positive sequence connection. beta_meter Hysteresis V alfa_meter 90°. V alfa_meter Size, phase and V c_grid same.

[0127] Case 6: Volt1 connected to V c_grid , Volt2 connects to V b_grid , Volt3 connected to V a_grid This is an incorrect connection method, which is a negative sequence connection. beta_meter Advanced V alfa_meter 90°. V alfa_meter Size, phase and V c_grid same.

[0128] According to the above relationship, the connection phase sequence of the meter voltage sampling can be determined. For example, Volt1 is connected to the grid phase A, Volt3 is connected to the grid phase C, and Volt2 is connected to the grid phase B, which is connection mode 2. Then the calculated V beta_meter Advanced V alfa_meter 90° is the negative sequence connection mode. alfa_meter With the instantaneous current of phase A I a_meter、 Phase B instantaneous current I b_ meter and the instantaneous current of phase C I c_ meter The angle relationship, if V alfa_meter Lag I a_meter 90°, it can be determined that the voltage sampling of the meter is connection mode 2. After identifying the current connection mode, the sampling amount is swapped, that is, Volt3 is regarded as the sampling of grid phase B, and Volt2 is regarded as the sampling of grid phase C, thus completing the phase sequence adaptation of voltage sampling.

[0129] In this embodiment, the connection mode is determined based on the phase of the first voltage component and the second voltage component, which can simplify the process of determining the voltage sampling phase sequence. Based on the determined connection mode, the voltage sampling phase sequence of the meter is determined based on the first voltage component and the three-phase instantaneous current. This not only determines whether the voltage sampling phase sequence of the meter is correct, but also determines the incorrect connection mode of the voltage sampling phase sequence if the voltage sampling phase sequence is incorrect, which is beneficial for subsequent replacement of the sampling amount and adaptive adjustment of the voltage sampling phase sequence.

[0130] To better understand the above embodiment, an optional embodiment is explained in detail below. In one embodiment, a method for adjusting the phase sequence of an electric meter is proposed, in which the electric meter interacts with the PCS via RS-485. Under the instruction of the electric meter, the PCS will send a preset reactive current. The electric meter can accurately identify the phase sequence misconnection of the electric meter by sampling the voltage and reactive current. The sampling amount is replaced according to the misconnection method to achieve the self-adaptation of the phase sequence of the electric meter voltage and current, ensuring the correctness of the electric meter power calculation. There is no need to manually adjust the meter wiring, which can reduce operation and maintenance costs.

[0131] Specifically, the connection between the PCS, grid, and electric meter is shown in Figure 1. The phase sequence of the PCS and grid is consistent. The electric meter samples the three-phase grid currents Cur1, Cur2, and Cur3 via external current transformers CT1, CT2, and CT3. The electric meter samples the three-phase grid voltages Volt1, Volt2, and Volt3 via external wiring. The electric meter calculates the active and reactive power of the energy storage system on the grid side based on the sampled voltages and currents. The current flowing out of the PCS is set to positive, and the current flowing into the PCS is set to negative.

[0132] like Figure 8 As shown in the figure, the PCS sends a command to the meter via RS485 in the self-test phase before grid connection to enable the automatic phase sequence adjustment function of the meter. After receiving the command, the meter will save the effective value of the three-phase grid current I detected. a_meter_old , I b_meter_old , I c_meter_old After the PCS self-test is completed and it enters the grid-connected state, it will send the preset reactive current I a_pcs_set , I b_pcs_set , I c_pcs_set The three-phase reactive currents are all different. The magnitude of the reactive current can be a set of arithmetic progressions. At the same time, the active power output of the PCS is limited to 0. The preset reactive current can be expressed as:

[0133]

[0134] Among them, I set_delta The difference between the reactive currents of two adjacent phases is preset.

[0135] When the PCS detects that the reactive current output by the PCS reaches the preset reactive current, it sends a command to the meter via RS485 to enable the meter to calculate the reactive current increment and set the effective value I of the three-phase grid current currently detected by the meter. a_meter_new , I b_meter_new and I c_meter_new , the instantaneous value of the three-phase current is I a_meter、 I b_ meter and I c_ meter , the reactive current increment is I a_meter_delta , Ib_meter_delta and I c_meter_delta According to the calculated reactive current increment, sort the minimum value I in the current increment in sequence. min , median I mid and the maximum value I max Based on the relationship between the current increment and the PCS reactive current setting value, it can be determined whether the meter's current detection accuracy meets the requirements (poor CT contact and sampling circuit abnormalities can lead to insufficient current detection accuracy). It can also be determined whether the meter's CT is connected incorrectly:

[0136]

[0137] First, determine whether the detection accuracy of the meter CT meets the requirements, set the first preset adjustment coefficient K1=0.8, and the second preset adjustment coefficient K2=1.2. The values ​​of K1 and K2 are mainly determined by the reactive power control accuracy of the PCS and the required current detection accuracy of the meter. min , I mid , I max If the following inequality is satisfied, it means that the meter's current detection accuracy meets the requirements. Otherwise, the meter's current detection accuracy is insufficient. The comparison relationship is as follows:

[0138]

[0139] Further comparison can determine the CT connection phase sequence. For example, CT1 is connected to the grid phase A, CT2 is connected to the grid phase C, and CT3 is connected to the grid phase B. min =I a_meter_delta , I mid = I c_meter_delta , I max = I b_meter_delta At this point, you can swap the sampling amounts, setting the current sampling amount of CT2 to Cur3 and the current sampling amount of CT3 to Cur2, recalculate the reactive current increment, and re-determine the meter current sampling accuracy and CT connection phase sequence. This completes the current phase sequence adaptation.

[0140] Secondly, determine whether the phase sequence of the meter voltage sampling is correct. Figure 9 As shown, the phase voltages sampled by the meter are set to Volt1, Volt2, and Volt3, which are equivalent to V a 、V b 、V c The sampled voltage is transformed by Clark to calculate the component V in the stationary coordinates. alfa_meter and V beta_meter .

[0141]

[0142] Set the grid voltage to V a_grid ,V b_grid ,V c_grid There are six situations for the connection between the meter voltage sampling and the power grid. Figure 1 , according to the first voltage component V alfa_meter and the second voltage component V beta_meter The relationship between the meter and the grid voltage can be obtained:

[0143] Case 1: Volt1 connected to V a_grid , Volt2 connects to V b_grid , Volt3 connected to V c_grid This is the correct connection method. It is a positive sequence connection, with V beta_meter Hysteresis V alfa_meter 90°, V alfa_meter Size, phase and V a_grid same.

[0144] Case 2: Volt1 connected to V a_grid , Volt3 connected to V b_grid , Volt2 connects to V c_grid This is an incorrect connection method. It is a negative sequence connection, and the phase V beta_meter Advanced V alfa_meter 90°, V alfa_meter Size, phase and V a_grid same.

[0145] Case 3: Volt1 connected to V b_grid , Volt2 connects to V c_grid , Volt3 connected to V a_grid This is an incorrect connection method. It is a positive sequence connection, and the phase V beta_meter Hysteresis V alfa_meter 90°, V alfa_meter Size, phase and V b_grid same.

[0146] Case 4: Volt1 connected to V b_grid , Volt2 connects to V a_grid , Volt3 connected to V c_grid This is an incorrect connection method and is also a negative sequence connection. beta_meter Advanced V alfa_meter 90°. V alfa_meter Size, phase and V b_grid same.

[0147] Case 5: Volt1 connected to V c_grid , Volt2 connects to V a_grid, Volt3 connected to V b_grid This is an incorrect connection method, which is also a positive sequence connection. beta_meter Hysteresis V alfa_meter 90°. V alfa_meter Size, phase and V c_grid same.

[0148] Case 6: Volt1 connected to V c_grid , Volt2 connects to V b_grid , Volt3 connected to V a_grid This is an incorrect connection method, which is a negative sequence connection. beta_meter Advanced V alfa_meter 90°. V alfa_meter Size, phase and V c_grid same.

[0149] According to the above relationship, the connection phase sequence of the meter voltage sampling can be determined. For example, Volt1 is connected to the grid phase A, Volt3 is connected to the grid phase C, and Volt2 is connected to the grid phase B, which is connection mode 2. Then the calculated V beta_meter Advanced V alfa_meter 90° is the negative sequence connection mode. alfa_meter With the instantaneous current of phase A I a_meter、 Phase B instantaneous current I b_ meter and the instantaneous current of phase C I c_ meter The angle relationship, if V alfa_meter Lag I a_meter 90°, it can be determined that the voltage sampling of the meter is connection mode 2. After identifying the current connection mode, the sampling amount is swapped, that is, Volt3 is regarded as the sampling of grid phase B, and Volt2 is regarded as the sampling of grid phase C, thus completing the phase sequence adaptation of voltage sampling.

[0150] After the aforementioned meter accuracy detection, phase sequence adaptation of meter voltage detection and current detection, and reverse adaptation of meter CT, active power and reactive power can be correctly calculated even when the meter voltage and current are out of phase, reducing operation and maintenance costs and improving system reliability.

[0151] It should be understood that, although the steps in the flowcharts of the above embodiments are shown in sequence as indicated by the arrows, these steps are not necessarily performed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be performed in other orders. Moreover, at least a portion of the steps in the flowcharts of the above embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily to be performed in sequence, but can be performed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0152] Based on the same inventive concept, embodiments of the present application further provide an electric meter phase sequence adjustment device for implementing the above-mentioned electric meter phase sequence adjustment method. The solution provided by this device is similar to the solution described in the above-mentioned method. Therefore, the specific limitations of one or more embodiments of the electric meter phase sequence adjustment device provided below can be found in the above-mentioned limitations of the electric meter phase sequence adjustment method and will not be further elaborated here.

[0153] In an exemplary embodiment, Figure 10 As shown, a phase sequence adjustment device for an electric meter is provided, which is applied to an electric meter. The electric meter is electrically connected to an inverter and a three-phase power grid respectively, and the inverter is connected to the three-phase power grid. The phase sequence adjustment device for the electric meter includes: a current acquisition module 1002, a current phase sequence determination module 1004, a voltage acquisition module 1006, a voltage phase sequence determination module 1008 and a phase sequence adjustment module 1010, wherein:

[0154] The current acquisition module 1002 is configured to calculate the reactive current increment of the inverter and obtain the three-phase instantaneous current of the three-phase grid if it is determined that the reactive current output by the inverter reaches a preset reactive current after the inverter enters the grid-connected state;

[0155] A current phase sequence determining module 1004 is configured to determine a current sampling phase sequence of an electric meter based on a reactive current increment;

[0156] A voltage acquisition module 1006 is configured to acquire the three-phase voltage of the inverter and perform a Clark transformation on the three-phase voltage to obtain a first voltage component and a second voltage component;

[0157] A voltage phase sequence determining module 1008 is configured to determine a voltage sampling phase sequence of the electric meter based on the first voltage component, the second voltage component, and the three-phase instantaneous current;

[0158] The phase sequence adjustment module 1010 is used to swap the sampling data corresponding to the incorrect current sampling phase sequence or voltage sampling phase sequence with the preset assignment data if the current sampling phase sequence or voltage sampling phase sequence is incorrect, so that the current sampling phase sequence and voltage sampling phase sequence match the phase sequence of the signal output by the inverter to the three-phase power grid.

[0159] In an exemplary embodiment, the current acquisition module is also used to obtain the effective value of the three-phase grid current and the initial value of the three-phase grid current after the inverter enters the grid-connected state, if it is determined that the reactive current output by the inverter reaches the preset reactive current; and calculate the reactive current increment based on the effective value of the three-phase grid current and the initial value of the three-phase grid current.

[0160] In an exemplary embodiment, the current acquisition module is further configured to obtain the effective value of the current three-phase grid current as the initial value of the three-phase grid current in response to a phase sequence adjustment instruction; the phase sequence adjustment instruction is sent by the inverter to the electric meter during the self-test phase.

[0161] In an exemplary embodiment, the current phase sequence determination module is also used to determine the minimum reactive current increment, the intermediate reactive current increment and the maximum reactive current increment based on the first-phase reactive current increment, the second-phase reactive current increment and the third-phase reactive current increment; and determine the current sampling phase sequence of the electric meter based on the magnitude relationship between the first-phase reactive current increment and the minimum reactive current increment, the magnitude relationship between the second-phase reactive current increment and the intermediate reactive current increment, and the magnitude relationship between the third-phase reactive current increment and the maximum reactive current increment.

[0162] In an exemplary embodiment, the current phase sequence determination module is also used to determine that the current sampling phase sequence of the meter is correct if the first phase reactive current increment is equal to the minimum reactive current increment, the second phase reactive current increment is equal to the intermediate reactive current increment, and the third phase reactive current increment is equal to the maximum reactive current increment.

[0163] In an exemplary embodiment, an accuracy judgment module is further included, which is used to judge whether the current sampling accuracy of the electric meter meets the preset sampling accuracy requirement conditions based on the reactive current increment and the preset reactive current.

[0164] In an exemplary embodiment, the accuracy judgment module is further used to determine the reactive current range based on a preset adjustment coefficient and a preset reactive current; and to judge whether the current sampling accuracy of the meter meets the preset sampling accuracy requirement based on the reactive current increment and the reactive current range.

[0165] In an exemplary embodiment, the voltage phase sequence determination module is also used to determine the connection mode according to the phase of the first voltage component and the second voltage component; based on the determined connection mode, the voltage sampling phase sequence of the electric meter is determined according to the first voltage component and the three-phase instantaneous current.

[0166] In an exemplary embodiment, the three-phase instantaneous current includes the instantaneous current of phase A, the instantaneous current of phase B, and the instantaneous current of phase C, and the voltage phase sequence determination module is further configured to:

[0167] When the connection mode is determined to be positive sequence connection:

[0168] If the phase of the first voltage component lags the phase of the instantaneous current of phase A by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the phase A voltage, the second sampled voltage data corresponds to the phase B voltage, and the third sampled data corresponds to the phase C voltage; or;

[0169] If the phase of the first voltage component lags the phase of the instantaneous current of phase B by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the voltage of phase B, the second sampled voltage data corresponds to the voltage of phase C, and the third sampled data corresponds to the voltage of phase A; or;

[0170] If the phase of the first voltage component lags the phase of the instantaneous current of phase C by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the phase C voltage, the second sampled voltage data corresponds to the phase A voltage, and the third sampled data corresponds to the phase B voltage; or;

[0171] When the connection mode is determined to be negative sequence connection:

[0172] If the phase of the first voltage component lags the phase of the instantaneous current of phase A by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the phase A voltage, the second sampled voltage data corresponds to the phase C voltage, and the third sampled data corresponds to the phase B voltage; or;

[0173] If the phase of the first voltage component lags the phase of the instantaneous current of phase B by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the voltage of phase B, the second sampled voltage data corresponds to the voltage of phase A, and the third sampled data corresponds to the voltage of phase C; or;

[0174] If the phase of the first voltage component lags the phase of the instantaneous current of phase C by 90°, the voltage sampling phase sequence of the meter is determined to be: the first sampled voltage data corresponds to the phase C voltage, the second sampled voltage data corresponds to the phase B voltage, and the third sampled data corresponds to the phase A voltage.

[0175] Each module in the aforementioned electric meter phase sequence adjustment device can be implemented in whole or in part through software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in hardware form, or can be stored in a memory in the computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0176] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0177] In an exemplary embodiment, a sampling device is provided, which is applied between an inverter and a three-phase power grid. The sampling device includes an electric meter and a current detection device, and the current detection device is connected to the electric meter. The current detection device is arranged between the connecting line between the inverter and the three-phase power grid, and is used to detect the current on the connecting line and send the current data to the electric meter. The electric meter is electrically connected to the connecting line between the inverter and the power grid. The electric meter is used to implement the steps of the method of any of the above embodiments.

[0178] In an exemplary embodiment, a grid-connected power generation system is provided, including an inverter, a three-phase power grid and a sampling device as described in the above embodiment, wherein the inverter is electrically connected to the three-phase power grid, and each phase of the inverter is connected one-to-one with each phase of the three-phase power grid.

[0179] Those skilled in the art will 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. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. In particular, any reference to memory, database, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the various embodiments provided herein may be, but are not limited to, general-purpose processors, central processing units (CPUs), graphics processing units (GPUs), digital signal processors (DSPs), programmable logic devices (PLDs), quantum computing-based data processing logic devices, artificial intelligence (AI) processors, and the like.

[0180] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0181] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A method for adjusting the phase sequence of an electric meter, characterized in that: Applied to an electric meter, the electric meter is electrically connected to an inverter and a three-phase power grid respectively, the inverter is electrically connected to the three-phase power grid, and the method includes: After the inverter enters the grid-connected state, if it is determined that the reactive current output by the inverter reaches a preset reactive current, calculating the reactive current increment of the inverter and obtaining the three-phase instantaneous current of the three-phase grid; determining a current sampling phase sequence of the electric meter based on the reactive current increment; Obtaining a three-phase voltage of the inverter, and performing a Clark transformation on the three-phase voltage to obtain a first voltage component and a second voltage component; determining a voltage sampling phase sequence of the electric meter according to the first voltage component, the second voltage component, and the three-phase instantaneous current; If the current sampling phase sequence or the voltage sampling phase sequence is incorrect, the corresponding sampling data corresponding to the incorrect current sampling phase sequence or voltage sampling phase sequence are swapped with the preset assignment data, so that the current sampling phase sequence and the voltage sampling phase sequence match the phase sequence of the signal output by the inverter to the three-phase power grid.

2. The method according to claim 1, characterized in that After the inverter enters the grid-connected state, if it is determined that the reactive current output by the inverter reaches a preset reactive current, calculating the reactive current increment includes: After the inverter enters the grid-connected state, if it is determined that the reactive current output by the inverter reaches a preset reactive current, obtaining the effective value of the three-phase grid current and the initial value of the three-phase grid current; A reactive current increment is calculated based on the effective value of the three-phase grid current and the initial value of the three-phase grid current.

3. The method according to claim 2, characterized in that The method further comprises: In response to a phase sequence adjustment instruction, an effective value of the current three-phase grid current is obtained as an initial value of the three-phase grid current; the phase sequence adjustment instruction is sent by the inverter to the electric meter during a self-test phase.

4. The method according to claim 1, wherein The reactive current increment includes a first-phase reactive current increment, a second-phase reactive current increment, and a third-phase reactive current increment. Determining the current sampling phase sequence of the electric meter based on the reactive current increment includes: determining a minimum reactive current increment, an intermediate reactive current increment, and a maximum reactive current increment according to the first-phase reactive current increment, the second-phase reactive current increment, and the third-phase reactive current increment; The current sampling phase sequence of the electric meter is determined according to the magnitude relationship between the first-phase reactive current increment and the minimum reactive current increment, the magnitude relationship between the second-phase reactive current increment and the intermediate reactive current increment, and the magnitude relationship between the third-phase reactive current increment and the maximum reactive current increment.

5. The method according to claim 4, characterized in that The determining the current sampling phase sequence of the electric meter according to the magnitude relationship between the first-phase reactive current increment and the minimum reactive current increment, the magnitude relationship between the second-phase reactive current increment and the intermediate reactive current increment, and the magnitude relationship between the third-phase reactive current increment and the maximum reactive current increment includes: If the first-phase reactive current increment is equal to the minimum reactive current increment, the second-phase reactive current increment is equal to the intermediate reactive current increment, and the third-phase reactive current increment is equal to the maximum reactive current increment, it is determined that the current sampling phase sequence of the electric meter meets the preset current sampling phase sequence.

6. The method according to claim 1, characterized in that After the inverter enters the grid-connected state, if it is determined that the reactive current output by the inverter reaches a preset reactive current, the reactive current increment is calculated, and the three-phase instantaneous current is sampled, the method further includes: According to the reactive current increment and the preset reactive current, it is determined whether the current sampling accuracy of the electric meter meets the preset sampling accuracy requirement condition.

7. The method according to claim 6, characterized in that The determining, based on the reactive current increment and the preset reactive current, whether the current sampling accuracy of the electric meter meets a preset sampling accuracy requirement condition includes: Determining a reactive current range according to a preset adjustment coefficient and the preset reactive current; According to the reactive current increment and the reactive current range, it is determined whether the current sampling accuracy of the electric meter meets a preset sampling accuracy requirement condition.

8. The method according to claim 1, characterized in that The determining the voltage sampling phase sequence of the electric meter according to the first voltage component, the second voltage component and the three-phase instantaneous current includes: determining a connection mode according to the phases of the first voltage component and the second voltage component; the connection mode includes a positive sequence connection and a negative sequence connection; Based on the determined connection mode, a voltage sampling phase sequence of the electric meter is determined according to the first voltage component and the three-phase instantaneous current.

9. The method according to claim 8, characterized in that The three-phase instantaneous current includes an A-phase instantaneous current, a B-phase instantaneous current, and a C-phase instantaneous current. The determining, based on the determined connection mode and according to the first voltage component and the three-phase instantaneous current, of the voltage sampling phase sequence of the electric meter includes: When the connection mode is determined to be positive sequence connection: If the phase of the first voltage component lags the phase of the instantaneous current of phase A by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the phase A voltage, the second sampled voltage data corresponds to the phase B voltage, and the third sampled data corresponds to the phase C voltage; or; If the phase of the first voltage component lags the phase of the instantaneous current of the phase B by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the phase B voltage, the second sampled voltage data corresponds to the phase C voltage, and the third sampled data corresponds to the phase A voltage; or; If the phase of the first voltage component lags the phase of the instantaneous current of phase C by 90°, the voltage sampling phase sequence of the electric meter is determined as follows: the first sampled voltage data corresponds to the phase C voltage, the second sampled voltage data corresponds to the phase A voltage, and the third sampled data corresponds to the phase B voltage; or When the connection mode is determined to be negative sequence connection: If the phase of the first voltage component lags the phase of the instantaneous current of phase A by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the phase A voltage, the second sampled voltage data corresponds to the phase C voltage, and the third sampled data corresponds to the phase B voltage; or: If the phase of the first voltage component lags the phase of the instantaneous current of phase B by 90°, the voltage sampling phase sequence of the electric meter is determined as follows: the first sampled voltage data corresponds to the phase B voltage, the second sampled voltage data corresponds to the phase A voltage, and the third sampled data corresponds to the phase C voltage; or If the phase of the first voltage component lags the phase of the C-phase instantaneous current by 90°, the voltage sampling phase sequence of the electric meter is determined to be: the first sampled voltage data corresponds to the C-phase voltage, the second sampled voltage data corresponds to the B-phase voltage, and the third sampled data corresponds to the A-phase voltage.

10. A sampling device, characterized in that: Applied between an inverter and a three-phase power grid, the sampling device includes an electric meter and a current detection device, and the current detection device is connected to the electric meter; The current detection device is arranged between the connection line between the inverter and the three-phase power grid, and is used to detect the current on the connection line and send the current data to the electric meter. The electric meter is electrically connected to the connection line between the inverter and the three-phase power grid. The electric meter is used to implement the steps of any one of the methods described in claims 1 to 9.

11. A grid-connected power generation system, characterized in that: The system comprises an inverter, a three-phase power grid and the sampling device according to claim 10, wherein the inverter is electrically connected to the three-phase power grid, and each phase of the inverter is connected to each phase of the three-phase power grid in a one-to-one correspondence.

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