Energy storage system and method for correcting collected power of electricity meter of energy storage system

Abstract

The invention discloses an energy storage system and a method for correcting the collected power of an electric meter of the energy storage system. The method for correcting the collected power of the electric meter of the energy storage system comprises the following steps of S1, controlling the i-th phase independent output power of an inverter; s2, the ammeter collects the voltage, current, active power and apparent power of each phase of the power grid, and calculates the absolute value of the power factor of each phase of the power grid according to the active power and apparent power of each phase; s3, determining the CT wiring condition of the ammeter according to the absolute value of the power factor of each phase of the power grid; and S4, correcting to obtain the real apparent power and the real active power of the ith phase of the power grid by combining the voltage and the current of each phase of the power grid and the CT wiring condition of the electricity meter. According to the energy storage system and the ammeter acquisition power correction method thereof, the CT wiring condition is identified through the absolute value of the power factor, and correct power data can be directly recovered.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage systems, and in particular to an energy storage system and a method for correcting the power collected by an electricity meter thereof. Background Art

[0002] The energy storage industry is developing rapidly, and the number of household energy storage products is increasing day by day. Many household energy storage inverter systems are equipped with electricity meters for data collection. However, during the installation process, if the CT of the electricity meter is connected wrongly, it will cause the energy storage inverter system to collect incorrect data, resulting in incorrect power scheduling.

[0003] There is a prior art method for detecting the connection of the current transformer of an electricity meter in an energy storage system. By observing the change of the actual charging and discharging power through the charging and discharging actions, it is determined whether the CT wiring is normal; although this method can identify the CT wiring error, the CT wiring must be manually adjusted correctly to obtain accurate data.

[0004] There is also a prior art device and method for detecting the connection of the current transformer of an electricity meter in an energy storage system. This method makes the energy storage system enter the off-grid and loaded state, uses a simulated load, and compares the power of the simulated load with the power collected by the electricity meter to determine whether the CT is connected wrongly; this method requires the energy storage system to enter the off-grid mode, and additional auxiliary equipment and circuits are required to complete this detection, which is relatively complex and not easy to implement for general users.

[0005] The disclosure of the above background art content is only used to assist in understanding the concept and technical solution of the present invention, and it does not necessarily belong to the prior art of this patent application. Without clear evidence indicating that the above content was publicly available on the filing date of this patent application, the above background art should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0006] To solve the above technical problems, the present invention proposes an energy storage system and a method for correcting the power collected by an electricity meter thereof, which can identify the CT wiring situation through the absolute value of the power factor and directly restore the correct power data.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention discloses a method for correcting the power collected by an electricity meter of an energy storage system, including the following steps:

[0009] S1: Control the i-th phase of the inverter to output power separately;

[0010] S2: The electricity meter collects the voltage, current, active power, and apparent power of each phase of the power grid, and calculates the absolute value of the power factor of each phase of the power grid according to the active power and apparent power of each phase;

[0011] S3: Determine the CT wiring condition of the electricity meter according to the absolute value of the power factor of each phase of the power grid.

[0012] S4: Combine the voltage and current of each phase of the power grid and the CT wiring condition of the electricity meter, and correct to obtain the true apparent power and true active power of the i-th phase of the power grid.

[0013] Preferably, in step S3, it includes: If it is judged that the absolute value of the power factor of each phase of the power grid is less than 0.1, it indicates that the CT of the i-th phase of the electricity meter is not connected. At this time, after adjusting the wiring condition of the CT of the electricity meter, return to step S1.

[0014] Preferably, in step S3, it includes: If it is judged that the absolute value of the power factor of the i-th phase of the power grid is less than 0.1, and the absolute value of the power factor of the j-th phase of the power grid is within the range of [0.5, 0.7), it indicates that the CT of the j-th phase of the electricity meter is wrongly connected to the i-th phase of the power grid; and according to the similarity or difference between the direction of the active power of the j-th phase of the power grid collected by the electricity meter and the direction of the output power of the i-th phase of the inverter, determine the orientation of the CT of the j-th phase of the electricity meter wrongly connected to the i-th phase, where j≠i.

[0015] Preferably, in step S3: If the direction of the active power of the j-th phase of the power grid collected by the electricity meter is the same as the direction of the output power of the i-th phase of the inverter, it means that the orientation of the CT of the j-th phase wrongly connected to the i-th phase of the power grid is reverse; if the direction of the active power of the j-th phase of the power grid collected by the electricity meter is opposite to the direction of the output power of the i-th phase of the inverter, it means that the orientation of the CT of the j-th phase wrongly connected to the i-th phase of the power grid is positive.

[0016] Preferably, in step S4: Calculate the true apparent power of the i-th phase of the power grid according to the following formula:

[0017] RealGrid_S Li =MeterGrid_I Lj _ rms *MeterGrid_V Li _ rms

[0018] In the formula, RealGrid_S Li represents the true apparent power of the i-th phase of the power grid, MeterGrid_I Lj _ rms represents the effective value of the current collected by the CT of the j-th phase of the electricity meter, MeterGrid_V Li _ rms represents the effective value of the voltage collected by the i-th phase of the electricity meter;

[0019] When the orientation of the CT of the j-th phase wrongly connected to the i-th phase of the power grid is reverse, calculate the true active power of the i-th phase of the power grid:

[0020] When the orientation of the CT of the j-th phase connected to the i-th phase of the power grid is positive, the true active power of the i-th phase of the power grid is calculated as follows:

[0021] Among them, RealGrid_P Li represents the true active power of the i-th phase of the power grid, V Li represents the instantaneous voltage value collected by the i-th phase of the electricity meter, and I Lj represents the instantaneous current value collected by the j-th phase of the CT of the electricity meter.

[0022] Preferably, in step S3, it includes: if it is determined that the absolute value of the power factor of the i-th phase of the power grid is within the range of (0.8, 1], it indicates that the CT of the i-th phase of the electricity meter is correctly connected to the i-th phase of the power grid; and according to the similarity or difference between the direction of the active power of the i-th phase of the power grid collected by the electricity meter and the direction of the output power of the i-th phase of the inverter, the orientation of the CT of the i-th phase of the electricity meter correctly connected to the i-th phase of the power grid is determined.

[0023] Preferably, in step S3: if the direction of the active power of the i-th phase is the same as the direction of the output power of the i-th phase of the inverter, it indicates that the orientation of the CT of the i-th phase correctly connected to the i-th phase of the power grid is positive; if the direction of the active power of the i-th phase is opposite to the direction of the output power of the i-th phase of the inverter, it indicates that the orientation of the CT of the i-th phase correctly connected to the i-th phase of the power grid is negative.

[0024] Preferably, in step S4: the true apparent power of the i-th phase of the power grid is calculated according to the following formula:

[0025] RealGrid_S Li = MeterGrid_I Li _ rms *MeterGrid_V Li _ rms

[0026] In the formula, RealGrid_S Li represents the true apparent power of the i-th phase of the power grid, MeterGrid_I Li _ rms represents the effective current value collected by the CT of the i-th phase of the electricity meter, and MeterGrid_V Li _ rms represents the effective voltage value collected by the i-th phase of the electricity meter;

[0027] When the orientation of the CT of the i-th phase of the electricity meter correctly connected to the i-th phase is positive, the true active power of the i-th phase of the power grid is calculated as follows:

[0028] When the orientation of the CT of the i-th phase of the electricity meter correctly connected to the i-th phase is negative, the true active power of the i-th phase of the power grid is calculated as follows:

[0029] Among them, RealGrid_P Li represents the real active power of the i-th phase of the power grid, and V Li represents the instantaneous voltage value collected by the i-th phase of the electricity meter, and I Li represents the instantaneous current value collected by the i-th phase of the CT of the electricity meter.

[0030] Preferably, when the energy storage system is a polyphase energy storage system, steps S1 to S4 are repeatedly executed to correct and obtain the real apparent power and real active power of each phase of the power grid.

[0031] In a second aspect, the present invention discloses an energy storage system, including an inverter, an electricity meter, and a power grid. The inverter is connected to the power grid, and the electricity meter is connected to the power grid to collect the voltage, current, active power, and apparent power of each phase of the power grid. The electricity meter includes a CT, and each phase of the CT is respectively connected to each phase of the power grid, and the electricity meter is in communication connection with the inverter. The energy storage system is used to correct the real apparent power and real active power of each phase of the power grid according to the method for correcting the power collected by the electricity meter of the energy storage system described in the first aspect.

[0032] In a third aspect, the present invention discloses a computer-readable storage medium, in which a computer program is stored. Among them, the computer program is set to be run by a processor to execute the method for correcting the power collected by the electricity meter of the energy storage system described in the first aspect.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: The energy storage system and the method for correcting the power collected by its electricity meter disclosed in the present invention control each phase of the inverter to separately output power to the power grid, calculate the absolute value of the power factor of each phase of the power grid by collecting the active power and apparent power of each phase of the power grid through the electricity meter, and further judge the wiring situation of the CT of the electricity meter in combination with the characteristics of the absolute value of the power factor, and calculate the collected data to restore the correct power data; thus, it is possible to directly obtain the correct power grid power without manually adjusting the CT wiring in the case of incorrect or reverse connection; in this solution, it is possible to realize intelligent detection of the CT wiring situation and calibration without relying on additional auxiliary equipment and circuits, which is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a flowchart of the method for correcting the power collected by the electricity meter of the energy storage system disclosed in the preferred embodiment of the present invention;

[0035] Figure 2 is a framework diagram of the energy storage system in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is merely exemplary and not intended to limit the scope of the present invention and its applications.

[0037] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, the connection can be for a fixing function or for a circuit / signal communication function.

[0038] It should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0039] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0040] The following first makes corresponding explanatory descriptions of the terms involved in this case.

[0041] Energy storage system: The energy storage system mentioned in this case includes an energy storage inverter, and grid-side data is collected through an electricity meter.

[0042] CT: Current transformer, a device for detecting the current of the system, and the collected data is transmitted to the system for power calculation.

[0043] Power factor of the power grid: It is the ratio of the active power to the apparent power in the power grid, reflecting the utilization efficiency of the electrical equipment for the power grid, and can be expressed by the mathematical formula: Where represents the power factor of the power grid, P represents the active power of the power grid, and S represents the apparent power of the power grid.

[0044] As Figure 1 shown, a method for correcting the power collected by the electricity meter of an energy storage system is disclosed in the preferred embodiment of the present invention, including the following steps:

[0045] S1: Control the individual output power P of the i-th phase of the inverter i .

[0046] The output power P of the inverter i can be positive or negative. It is defined that the direction of the inverter delivering power to the grid is positive (the output power P i is positive), and the direction of the grid feeding back power to the inverter is negative (the output power P i is negative).

[0047] S2: Collect the voltage, current, active power, and apparent power of each phase of the grid through the electricity meter, and calculate the absolute value of the power factor of each phase of the grid based on the active power and apparent power of each phase;

[0048] The voltage V of each phase of the grid is collected by the voltage sensor (PT) in the electricity meter, and the current I of each phase of the grid is collected by the current transformer (CT) in the electricity meter respectively. The premise for implementing this solution is that the phase sequence of the voltage sensor has been in one-to-one correspondence with the grid phase sequence.

[0049] According to the voltage V and current I of each phase of the grid, the apparent power S of each phase of the grid can be calculated as follows in formula (1):

[0050] S = V rms *I rms Formula (1)

[0051] where V rms is the root mean square (RMS) value of the voltage, that is, the root mean square value of the AC voltage in one cycle; I rms is the root mean square value of the current, that is, the root mean square value of the current in one cycle.

[0052] The active power P is obtained by integrating the current I and voltage V over one grid cycle, as follows in formula (2):

[0053]

[0054] where V is the grid voltage collected in real time, I is the grid current collected in real time by the current transformer, and T is the power frequency period of the grid.

[0055] According to the apparent power S and active power P, the absolute value of the power factor PF can be calculated, as follows in formula (3):

[0056]

[0057] S3: Determine the CT wiring condition of the electricity meter based on the absolute value of the power factor of each phase of the grid;

[0058] Among them, according to the absolute value of the power factor of each phase of the power grid, there are the following three situations for determining the CT connection of the electricity meter:

[0059] a. If it is judged that the absolute value of the power factor of each phase of the power grid is less than 0.1, it indicates that the i-th phase of the electricity meter CT is not connected. At this time, after adjusting the wiring of the i-th phase of the electricity meter CT, return to step S1.

[0060] b. If it is judged that the absolute value of the power factor of the i-th phase of the power grid is less than 0.1, and the absolute value of the power factor of the j-th phase of the power grid is within the range of [0.5, 0.7), it indicates that the j-th phase of the electricity meter CT is wrongly connected to the i-th phase of the power grid; and according to whether the direction of the active power of the j-th phase of the power grid collected by the electricity meter is the same as or different from the direction of the output power of the i-th phase of the inverter, determine the orientation of the j-th phase of the electricity meter CT wrongly connected to the i-th phase of the power grid, where j ≠ i.

[0061] If the direction of the active power of the j-th phase of the power grid collected by the electricity meter is the same as the direction of the output power of the i-th phase of the inverter, it means that the orientation of the j-th phase CT wrongly connected to the i-th phase of the power grid is reverse; if the direction of the active power of the j-th phase of the power grid collected by the electricity meter is opposite to the direction of the output power of the i-th phase of the inverter, it means that the orientation of the j-th phase CT wrongly connected to the i-th phase of the power grid is positive.

[0062] The reason is that for three-phase electricity, the phase difference is 120°, and the voltage and current of its L1 / L2 / L3 phases can be expressed as follows:

[0063] V L1 =V m *sin(ωt)

[0064] V L2 =V m *sin(ωt - 120)

[0065] V L3 =V m *sin(ωt + 120)

[0066] I L1 =I m *sin(ωt + b)

[0067] I L2 =I m *sin(ωt - 120 + b)

[0068] I L3 =I m *sin(ωt + 120 + b) Formula group (4)

[0069] Among them, V m is the peak value of the voltage, I m$I_{m}$ is the peak value of the current, and $b$ is the phase angle by which the current lags behind the voltage. When the power factor of the power grid is relatively high, the value of $b$ can be ignored.

[0070] The output power of phase L1 of the inverter, and phases L2 and L3 do not output power. When the L1 phase of the meter CT is correctly connected to the L1 phase of the power grid, the active power measured by the L1 phase of the power grid is expressed by the following formula (5):

[0071]

[0072] When the L2 phase of the meter CT is wrongly connected to the L1 phase of the power grid, the current actually collected by the L2 phase of the meter CT is the current of the L1 phase of the power grid. The active power measured by the L2 phase of the power grid is expressed by the following formula (6):

[0073]

[0074] When the L3 phase of the meter CT is wrongly connected to the L1 phase of the power grid, the current actually collected by the L3 phase of the meter CT is the current of the L1 phase of the power grid. The active power measured by the L3 phase of the power grid is expressed by the following formula (7):

[0075]

[0076] Therefore, combining formulas (5)-(7), it can be known that if the direction of the active power of the j-th phase of the power grid collected by the meter is the same as the direction of the output power of the i-th phase of the inverter, it means that the orientation of the j-th phase CT wrongly connected to the i-th phase of the power grid is reverse; if the direction of the active power of the j-th phase of the power grid collected by the meter is opposite to the direction of the output power of the i-th phase of the inverter, it means that the orientation of the j-th phase CT wrongly connected to the i-th phase of the power grid is positive.

[0077] c. If it is judged that the absolute value of the power factor of the i-th phase of the power grid is within the range of (0.8, 1], it indicates that the i-th phase CT of the meter is correctly connected to the i-th phase of the power grid; and according to the similarity or difference between the direction of the active power of the i-th phase of the power grid collected by the meter and the direction of the output power of the i-th phase of the inverter, determine the orientation of the i-th phase CT of the meter correctly connected to the i-th phase of the power grid.

[0078] If the direction of the active power of the i-th phase is the same as the direction of the output power of the i-th phase of the inverter, it means that the orientation of the i-th phase CT correctly connected to the i-th phase of the power grid is positive; if the direction of the active power of the i-th phase is opposite to the direction of the output power of the i-th phase of the inverter, it means that the orientation of the i-th phase CT correctly connected to the i-th phase of the power grid is reverse.

[0079] S4: Combine the voltage and current of each phase of the power grid and the CT wiring situation of the meter to correct and obtain the true apparent power and true active power of the i-th phase of the power grid.

[0080] Corresponding to the three cases of the CT connection of the electricity meter in step S3, among which, when step S3 is confirmed as case a, due to the problem of missing connection, the power cannot be restored. Therefore, it is necessary to adjust the CT connection of the electricity meter and return to step S1.

[0081] When step S3 is confirmed as case b, the true apparent power of the i-th phase of the power grid is calculated according to formula (8):

[0082] RealGrid_S Li =MeterGrid_I Lj _ rms *MeterGrid_V Li _ rms Formula (8)

[0083] In the formula, RealGrid_S Li represents the true apparent power of the i-th phase of the power grid, and MeterGrid_I Lj _ rms represents the effective value of the current collected by the j-th phase of the CT of the electricity meter, and MeterGrid_V Li _ rms represents the effective value of the voltage collected by the i-th phase of the electricity meter.

[0084] When the j-th phase of the electricity meter CT is wrongly connected to the i-th phase of the power grid and the orientation is positive, the true active power of the i-th phase of the power grid is calculated as the following formula (9):

[0085]

[0086] In the formula, RealGrid_P Li represents the true active power of the i-th phase of the power grid, V Li represents the instantaneous voltage value collected by the i-th phase of the electricity meter, and I Lj represents the instantaneous current value collected by the j-th phase of the electricity meter CT.

[0087] When the j-th phase of the electricity meter CT is wrongly connected to the i-th phase of the power grid and the orientation is negative, the true active power of the i-th phase of the power grid is calculated as the following formula (10):

[0088]

[0089] When step S3 is confirmed as case c, the true apparent power of the i-th phase of the power grid is calculated according to the following formula 11:

[0090] RealGrid_S Li =MeterGrid_I Li _ rms *MeterGrid_V Li _rms Formula (11)

[0091] Wherein, RealGrid_S Li represents the true apparent power of the i-th phase of the power grid, and MeterGrid_I Li _ rms represents the effective value of the current collected by the CT of the i-th phase of the electric meter, and MeterGrid_V Li _ rms represents the effective value of the voltage collected by the i-th phase of the electric meter.

[0092] When the i-th phase of the CT of the electric meter is correctly connected to the i-th phase of the power grid and the orientation is positive, the true active power of the i-th phase of the power grid is calculated as the following formula (12):

[0093]

[0094] Wherein, RealGrid_P Li represents the true active power of the i-th phase of the power grid, V Li represents the instantaneous voltage value collected by the i-th phase of the electric meter, and I Li represents the instantaneous current value collected by the i-th phase of the CT of the electric meter.

[0095] When the i-th phase of the CT is correctly connected to the i-th phase of the power grid and the orientation is negative, the true active power of the i-th phase of the power grid is calculated as the following formula (13):

[0096]

[0097] Wherein, when the energy storage system is a single-phase energy storage system, steps S1 to S4 are executed once, that is, the true apparent power and true active power of each phase of the power grid are corrected; when the energy storage system is a multi-phase energy storage system, steps S1 to S4 need to be repeatedly executed to correct the true apparent power and true active power of each phase of the power grid.

[0098] Embodiment 2 of the present invention discloses an energy storage system, including an inverter, an electric meter and a power grid. The inverter is connected to the power grid, and the electric meter is connected to the power grid to collect the voltage and current of each phase of the power grid. The electric meter includes a CT, and each phase of the CT is respectively connected to each phase of the power grid, and the electric meter and the inverter are communicatively connected. The energy storage system is used to correct the true apparent power and true active power of each phase of the power grid according to the method for correcting the power collected by the electric meter of the energy storage system in Embodiment 1. Wherein, the true power factor of the power grid in this energy storage system is in the range of (0.8, 1], and this energy storage system can be a single-phase energy storage system, a two-wire energy storage system or a multi-phase energy storage system.

[0099] The following further describes in detail the method for correcting the power collected by the electricity meter of the energy storage system in Embodiment 1 of the present invention and the energy storage system disclosed in Embodiment 2 in combination with specific embodiments.

[0100] As Figure 2 shown, the energy storage system in this specific embodiment is a three-phase energy storage system, including an inverter 10, an electricity meter 20, and a power grid 30. The three phases of the inverter 10 are respectively connected to the three phases of the power grid 30. The electricity meter 20 is connected to the power grid 30 to collect the voltage and current of each phase of the power grid 30, so as to further calculate the apparent power, active power, and absolute value of the power factor of the three phases of the power grid 30. Specifically, the V1, V2, and V3 terminals of the electricity meter 20 are respectively connected to the three phases of the power grid 30, and the L1 phase, L2 phase, and L3 phase of the CT 21 of the electricity meter 20 are respectively connected to the three phases of the power grid 30 to detect the currents I1, I2, and I3 of the three phases of the power grid; the three phases of the PT 22 in the electricity meter 20 are respectively connected to the three phases of the power grid 30 to detect the voltages V1, V2, and V3 of the three phases of the power grid. There is a communication connection between the electricity meter 20 and the inverter 10, such as Figure 2 the COM (Communication Port, serial communication interface) connection shown in

[0101] In the installation process of the electricity meter 20, if the wiring of each phase of the CT 21 is connected wrongly, the data obtained by the inverter will be incorrect data, resulting in incorrect power scheduling; to solve the problem that the energy storage system cannot obtain the correct power grid power data due to the wrong connection of the CT 21, in this solution, by using the inverter 10 to output power to the power grid 30, calculate the absolute value of the power factor of each phase, and confirm whether there is a wrong connection of the CT 21 according to the absolute value of the power factor. If there is a wrong connection of the CT 21, then calculate according to the collected data to correct the obtained power data, and calculate the true apparent power and true active power of each phase of the correct power grid.

[0102] When the inverter 10 is connected to the grid without a load, after the inverter 10 is connected to the grid, the inverter 10 outputs power to the power grid 30 in each phase in turn. After outputting the power, record the corresponding characteristic data according to the data returned by the electricity meter 20. For the convenience of description, the direction of power flowing to the power grid 30 is represented as positive and is represented by 1, otherwise it is represented by -1.

[0103] When a certain phase (such as the L1 phase) of the inverter 10 outputs positive power (feeding power to the power grid), if the other phases of the CT (such as the L2 phase or L3 phase of the CT) are wrongly connected to the power grid of this phase, it will cause incorrect power to be calculated for the other phases of the power grid. And because of the phase difference, the apparent power of the other phases is much greater than the active power, and the absolute value of the power factor is generally close to 0.5. This solution is based on this characteristic to detect the wiring condition of the CT 21.

[0104] Taking the example of the L1-phase output of the inverter 10 with a fixed power, at this time, the output powers of other phases are 0, that is, the output powers of the L2 and L3 phases are 0, and there are the following three working conditions:

[0105] (1) None of the L1, L2, and L3 phases of the CT 21 are buckled on the grid L1 phase. Then, the absolute values of the power factors of the grid L1, L2, and L3 phases calculated by the electricity meter 20 are all close to 0, and the results are shown in Table 1:

[0106] Table 1 The first working condition

[0107] Power grid phase sequence CT phase sequence of the corresponding electricity meter CT orientation L1 None None

[0108] (2) The L2 or L3 phase of the CT 21 is buckled on the grid L1 phase. Correspondingly, the absolute value of the power factor of the grid L2 or L3 phase calculated by the electricity meter 20 is within the range of [0.5, 0.7); if the direction of the active power of the grid L2 or L3 phase calculated by the electricity meter 20 is the same as the direction of the output power of the inverter L1 phase, then the orientation of the L2 or L3 phase of the CT 21 is reverse, otherwise it is positive.

[0109] Taking the example that the L2 phase of the CT 21 is buckled to the L1 phase of the grid and the orientation is reverse, the results are shown in Table 2:

[0110] Table 2 The second working condition

[0111] Power grid phase sequence CT phase sequence of the corresponding electricity meter CT orientation L1 L2 Reverse

[0112] (3) The L1 phase of the CT21 is buckled to the L1 phase of the grid. Then, the absolute value of the power factor of the grid L1 phase calculated by the electricity meter 20 is within the range of (0.8, 1]; if the direction of the active power of the grid L1 phase calculated by the electricity meter 20 is positive, then the orientation of the L1 phase of the CT 21 is positive, otherwise it is reverse.

[0113] Taking the example that the L1 phase of the CT21 is buckled to the L1 phase of the grid and the orientation is positive, the results are shown in Table 3:

[0114] Table 3 The third working condition

[0115] Power grid phase sequence CT phase sequence of the corresponding electricity meter CT orientation L1 L1 Positive

[0116] According to the above steps, then control the L2 and L3 phases of the inverter 10 to output power separately in turn, so as to confirm the actual wiring situation of the CT 21 of the electricity meter 20 of the energy storage system.

[0117] The actual wiring condition of CT 21 of the electricity meter 20 is obtained. When there is a wrong connection of CT 21, although the power data returned by the electricity meter 20 is incorrect, the actual apparent power of the power grid can be restored. If the user inputs / auxiliary equipment detects the actual power factor of the power grid, the actual active power of the power grid can be further restored. Among them, if there is the first working condition, that is, the condition of CT being not connected, the power cannot be restored. Therefore, it is necessary to reconnect the CT and return to the initial step again.

[0118] The following describes how to restore the actual apparent power and active power of the power grid in combination with the above-mentioned second working condition.

[0119] RealGrid_S Li Is the true apparent power of the i-th phase of the power grid, RealGrid_P Li Is the true active power of the i-th phase of the power grid, MeterGrid_P Li Is the active power of the i-th phase calculated by the electricity meter, MeterGrid_I Li Is the current of the i-th phase collected by the electricity meter, MeterGrid_V Li Is the voltage of the i-th phase collected by the electricity meter.

[0120] Taking the output power of the L1 phase of the inverter as an example and being positive:

[0121] If the L2 phase of the CT is wrongly connected to the L1 phase of the power grid, at this time, the current collected by the electricity meter for the L2 phase is actually the current of the L1 phase of the power grid. Multiplying this current by the voltage of the L1 phase can obtain the true apparent power:

[0122] RealGrid_S L1 = MeterGrid_I L2 _ rms *MeterGrid_V L1 _ rms ;

[0123] Among them, the apparent power is a scalar without a sign; the effective value of the current MeterGrid_I L2 _ rms Collected by the electricity meter and the effective value of the voltage MeterGrid_V L1 _ rms Are also both scalars without a sign.

[0124] (1) If MeterGrid_P L2 ≥0 (MeterGrid_P L2 Is the active power of the L2 phase collected by the electricity meter, and the active power collected by the electricity meter has a sign), it indicates that the orientation of the wrong connection of the L2 phase of the electricity meter CT to the L1 phase of the power grid is reversed. Therefore

[0125] (2) If MeterGrid_P L2 <0, it indicates that the L2 phase of the meter CT is correctly connected to the L1 phase of the power grid in the positive direction. Therefore,

[0126] For the other two-phase power grids, if the CTs are wrongly connected, the restoration of the true apparent power and true active power follows the same steps as above.

[0127] When it comes to the third working condition, only when the CT orientation is reversed, the true active power needs to be negated.

[0128] The above scheme of the specific embodiment of the present invention is equally applicable to two-phase electricity meters and single-phase electricity meters. Although there is no problem of wrong connection for single-phase electricity meters, there may be a problem of reverse connection, and this case is equally applicable.

[0129] The method for correcting the power collected by the electricity meter of the energy storage system disclosed in the preferred embodiment of the present invention first identifies the situation where the CT of the electricity meter in the energy storage system is wrongly connected based on the change characteristics of the absolute value of the power factor when the CT is wrongly connected, and then performs corresponding calculations to restore the true power data in the case where the power calculation is incorrect due to the wrong connection of the CT. Therefore, through this method, the system can still operate normally when the CT is wrongly connected.

[0130] Embodiment 3 of the present invention discloses a computer-readable storage medium, in which a computer program is stored. Among them, the computer program is set to be run by a processor to execute the steps of the method for correcting the power collected by the electricity meter of the energy storage system in Embodiment 1 above.

[0131] Optionally, the above computer-readable storage medium may include, but is not limited to: USB flash drives, read-only memories (ROM for short), random access memories (RAM for short), mobile hard disks, magnetic disks, or optical discs and other various media that can store computer programs.

[0132] The background part of the present invention may include background information about the problems or environment of the present invention, rather than the description of the prior art by others. Therefore, the content included in the background art section is not an admission by the applicant of the prior art.

[0133] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, they can also make several substitutions or modifications to these described embodiments, and these substitution or modification methods should all be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description with reference to terms such as "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the scope defined by the appended claims.

Claims

1. A method for correcting the power collected by an electric meter of an energy storage system, characterized in that, Including the following steps: S1: Control the i-th phase of the inverter to output power separately; S2: The electricity meter collects the voltage, current, active power, and apparent power of each phase of the power grid, and calculates the absolute value of the power factor of each phase of the power grid according to the active power and apparent power of each phase; S3: Determine the CT wiring condition of the electricity meter according to the absolute value of the power factor of each phase of the power grid; S4: Combine the voltage, current of each phase of the power grid and the CT wiring condition of the electricity meter to correct and obtain the true apparent power and true active power of the i-th phase of the power grid.

2. The method for correcting the power collected by the electricity meter of the energy storage system according to claim 1, characterized in that, Step S3 includes: If it is judged that the absolute value of the power factor of each phase of the power grid is less than 0.1, it indicates that the CT of the i-th phase of the electricity meter is not connected. At this time, after adjusting the wiring condition of the CT of the electricity meter, return to step S1.

3. The method for correcting the power collected by the electricity meter of the energy storage system according to claim 1, characterized in that, Step S3 includes: If it is judged that the absolute value of the power factor of the i-th phase of the power grid is less than 0.1, and the absolute value of the power factor of the j-th phase of the power grid is within the range of [0.5, 0.7), it indicates that the CT of the j-th phase of the electricity meter is wrongly connected to the i-th phase of the power grid; and determine the orientation of the CT of the j-th phase of the electricity meter wrongly connected to the i-th phase of the power grid according to the same or different directions of the active power of the j-th phase of the power grid collected by the electricity meter and the output power direction of the i-th phase of the inverter, where j≠i.

4. The method for correcting the power collected by the electricity meter of the energy storage system according to claim 3, wherein In step S3: If the direction of the active power of the j-th phase of the power grid collected by the electricity meter is the same as the output power direction of the i-th phase of the inverter, it means that the orientation of the CT of the j-th phase wrongly connected to the i-th phase of the power grid is reverse; if the direction of the active power of the j-th phase of the power grid collected by the electricity meter is opposite to the output power direction of the i-th phase of the inverter, it means that the orientation of the CT of the j-th phase wrongly connected to the i-th phase of the power grid is positive.

5. The method for correcting the power collected by the electricity meter of the energy storage system according to claim 4, wherein In step S4: Calculate the true apparent power of the i-th phase of the power grid according to the following formula: RealGrid_S Li = MeterGrid_I Lj _ rms *MeterGrid_V Li _ rms Wherein, RealGrid_S Li represents the true apparent power of the i-th phase of the power grid, MeterGrid_I Lj _ rms represents the effective value of the current collected by the CT of the j-th phase of the meter, MeterGrid_V Li _ rms represents the effective value of the voltage collected by the i-th phase of the meter; When the orientation of the CT of the j-th phase is wrongly connected to the i-th phase of the power grid and is reversed, the true active power of the i-th phase of the power grid is calculated as follows: When the orientation of the CT of the j-th phase connected to the i-th phase of the power grid is positive, the true active power of the i-th phase of the power grid is calculated as follows: Among them, RealGrid_P Li represents the real active power of the i-th phase of the power grid, V Li represents the instantaneous voltage value collected by the i-th phase of the electricity meter, I Lj represents the instantaneous current value collected by the j-th phase of the CT of the electricity meter.

6. The method for correcting the power collected by the electricity meter of the energy storage system according to claim 1, characterized in that, Step S3 includes: If it is judged that the absolute value of the power factor of the i-th phase of the power grid is within the range of (0.8, 1], it indicates that the CT of the i-th phase of the electricity meter is correctly connected to the i-th phase of the power grid; and determine the orientation of the CT of the i-th phase of the electricity meter correctly connected to the i-th phase of the power grid according to the same or different directions of the active power of the i-th phase of the power grid collected by the electricity meter and the output power direction of the i-th phase of the inverter.

7. The method for correcting the power collected by the electricity meter of the energy storage system according to claim 6, characterized in that In step S3: If the direction of the active power of the i-th phase is the same as the output power direction of the i-th phase of the inverter, it means that the orientation of the CT of the i-th phase correctly connected to the i-th phase of the power grid is positive; if the direction of the active power of the i-th phase is opposite to the output power direction of the i-th phase of the inverter, it means that the orientation of the CT of the i-th phase correctly connected to the i-th phase of the power grid is reverse.

8. The method for correcting the power collected by the electricity meter of the energy storage system according to claim 7, wherein In step S4: Calculate the true apparent power of the i-th phase of the power grid according to the following formula: RealGrid_S Li = MeterGrid_I Li _ rms *MeterGrid_V Li _ rms Wherein, RealGrid_S Li represents the true apparent power of the i-th phase of the power grid, and MeterGrid_I Li _ rms represents the effective value of the current collected by the CT of the i-th phase of the meter, and MeterGrid_V Li _ rms represents the effective value of the voltage collected by the i-th phase of the meter; When the CT of the i-th phase of the electricity meter is correctly connected to the i-th phase with a positive orientation, the true active power of the i-th phase of the power grid is calculated as follows: When the CT of the i-th phase of the electricity meter is correctly connected to the i-th phase with the wrong orientation, the true active power of the i-th phase of the power grid is calculated as follows: Among them, RealGrid_P Li represents the real active power of the i-th phase of the power grid, V Li represents the instantaneous voltage value collected by the i-th phase of the electric meter, I Li represents the instantaneous current value collected by the CT of the i-th phase of the electric meter.

9. The method for correcting the power collected by the electricity meter of the energy storage system according to claim 1, characterized in that, When the energy storage system is a multi-phase energy storage system, repeat steps S1 to S4 to correct and obtain the true apparent power and true active power of each phase of the power grid.

10. A energy storage system, characterized in that, It includes an inverter, a power meter and a power grid. The inverter is connected to the power grid. The power meter is connected to the power grid for collecting the voltage, current, active power and apparent power of each phase of the power grid. The power meter contains a CT. Each phase of the CT is respectively connected to each phase of the power grid, and the power meter is communicatively connected to the inverter. The energy storage system is used to correct the true apparent power and true active power of each phase of the power grid according to the power meter acquisition power correction method of the energy storage system according to any one of claims 1 to 9.

11. A computer-readable storage medium, characterized in that, A computer program is stored in the computer-readable storage medium, wherein the computer program is configured to be run by a processor to execute the power meter acquisition power correction method of the energy storage system according to any one of claims 1 to 9.

Images