Adaptive control method and device for active power of inverter

Abstract

The invention relates to an inverter active power self-adaptive control method and device, and relates to the technical field of photovoltaic power generation, and the method comprises the steps: obtaining the parameter information outputted by a photovoltaic array at the current moment, calculating the current power and the power change rate, determining the current operation mode through combining the initial operation mode of the inverter and a preset switching condition, and carrying out the self-adaptive control of the active power of the inverter. The current operation mode is a first operation mode or a second operation mode, determining a voltage step length according to the current operation mode, the current power and a preset voltage step length adjustment rule, determining a reference voltage at the current moment, and generating an active power control signal to adjust a photovoltaic array working point. According to the invention, the operation mode and the voltage step length of the inverter can be adaptively adjusted according to the actual situation, the active power of the inverter is effectively controlled, and the working efficiency and the stability of the inverter are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a method and device for adaptively controlling active power of an inverter. Background Art

[0002] In the field of photovoltaic power generation technology, with the growing demand for energy and the emphasis on clean energy, grid-connected photovoltaic power generation systems have been widely used. They can convert solar energy into electricity and feed it into the power grid, providing green energy for society and greatly promoting the optimization of energy structure and sustainable development.

[0003] In grid-connected photovoltaic power generation systems, to maximize energy output, existing technologies generally use maximum power point tracking (MPPT) technology, which dynamically adjusts the operating voltage or current of the photovoltaic array so that it always operates near the maximum power point, thereby improving power generation efficiency.

[0004] However, traditional MPPT algorithms adjust the operating point of photovoltaic cells based on fixed logic during operation. When environmental conditions change rapidly, they are unable to adapt to rapidly changing grid conditions. Therefore, in complex situations, this control method struggles to meet the fast dynamic response and steady-state performance requirements of power control. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method and device for adaptively controlling active power of an inverter, aiming to solve at least one of the above technical problems.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] In a first aspect, the present application provides an inverter active power adaptive control method, which adopts the following technical solutions:

[0008] An inverter active power adaptive control method, comprising:

[0009] Obtaining parameter information of a photovoltaic array output at a current moment, the photovoltaic array being composed of a plurality of photovoltaic modules, the parameter information including current voltage and current current;

[0010] Calculating, based on the current voltage and the current current, the current power and the power change rate of the photovoltaic array at the current moment, wherein the power change rate is used to characterize the dynamic shift trend of the photovoltaic array operating point on the power-voltage curve;

[0011] Determining a current operating mode of the inverter at a current moment based on the current power, the power change rate, the initial operating mode of the inverter, and a preset operating mode switching condition, wherein the initial operating mode is the operating mode of the inverter at a moment before the current moment, and the current operating mode is a first operating mode or a second operating mode, wherein the first operating mode is an MPPT mode for controlling the photovoltaic array to operate at a maximum power point when there is no power limitation requirement, and the second operating mode is a flexible power control mode for controlling the operating point of the photovoltaic array to deviate from the maximum power point when there is a power limitation requirement;

[0012] Determining a voltage step size of the inverter based on a current operating mode, a current voltage, a current power, and a preset voltage step size adjustment rule of the inverter;

[0013] Based on the voltage step size and initial reference voltage of the inverter, a reference voltage of the inverter at a current moment is determined, and based on the reference voltage at the current moment and the current operating mode, an active power control signal is generated to adjust the operating point of the photovoltaic array, where the initial reference voltage is the reference voltage of the inverter at a moment before the current moment.

[0014] The beneficial effects of the present invention are as follows: by obtaining parameter information of the photovoltaic array, calculating the current power and power change rate, the current operating mode of the inverter is determined, and the voltage step size and reference voltage are determined according to the current operating mode and relevant rules, thereby generating an active power control signal to adjust the array operating point. The MPPT mode and the flexible power control mode can be adaptively combined, the voltage step size can be flexibly adjusted, and more flexible active power control can be achieved, which meets the fast dynamic response and steady-state performance of power control and can adapt to rapidly changing grid conditions.

[0015] On the basis of the above technical solution, the present invention can also be improved as follows.

[0016] Further, determining the current operating mode of the inverter at the current moment based on the current power, the power change rate, the initial operating mode of the inverter, and a preset operating mode switching condition includes:

[0017] If the initial operation mode of the inverter is the first operation mode, obtaining a set reference power threshold at the current moment;

[0018] Determining a power difference based on the current power and a set reference power threshold at a current moment;

[0019] When the power difference is greater than a first set difference threshold, determining that the current operating mode of the inverter at the current moment is the second operating mode;

[0020] or, when the first set reference power threshold at the current moment is inconsistent with the first set reference power threshold at the previous moment, determining that the current operating mode of the inverter at the current moment is the second operating mode;

[0021] Otherwise, it is determined that the current operating mode of the inverter at the current moment is the first operating mode.

[0022] The beneficial effect of adopting the above further scheme is: when the inverter initially operates in the first operating mode (MPPT mode), it decides whether to switch to the second operating mode (flexible power control mode) by comparing the difference between the current power and the set reference power threshold, or judging whether the set reference power threshold has changed, thereby realizing adaptive switching of the inverter operating mode under different power requirements, which helps the inverter to improve power generation efficiency and power tracking performance while meeting different power limit requirements.

[0023] Furthermore, the determining the current operating mode of the inverter at the current moment based on the current power, the power change rate, the initial operating mode of the inverter, and a preset operating mode switching condition further includes:

[0024] If the initial operation mode of the inverter is the second operation mode, when the power difference is not greater than a first set difference threshold and the power change rate at the current moment is less than the first set power change rate threshold, determining that the current operation mode of the inverter at the current moment is the first operation mode;

[0025] Otherwise, it is determined that the current operating mode of the inverter at the current moment is the second operating mode.

[0026] The beneficial effect of adopting the above further scheme is: by accurately judging whether to switch to the first operating mode when the initial operating mode of the inverter is the second operating mode based on the difference between the current power and the set reference power threshold and the power change rate at the current moment, flexible switching between the MPPT mode and the flexible power control mode is achieved, which improves the adaptability and flexibility of the inverter active power control and can better meet different power control requirements.

[0027] Further, if the current operating mode of the inverter is the first operating mode, determining the voltage step size of the inverter based on the current operating mode of the inverter, the current power, and a preset voltage step size adjustment rule includes:

[0028] determining a set step size threshold and a set step size coefficient of the inverter based on a first operating mode of the inverter;

[0029] Determining a first target step size and a first step size coefficient of the inverter based on a bidirectional disturbance algorithm, current power, a set step size threshold, and a set step size coefficient;

[0030] A voltage step size of the inverter is determined based on the first target step size and the first step size coefficient.

[0031] The beneficial effect of adopting the above further scheme is: when the inverter is in the first operating mode (MPPT mode), the bidirectional perturbation algorithm is combined with the set step threshold and the set step coefficient to determine the first target step size and the first step coefficient, and then determine the voltage step size. The voltage step size can be dynamically adjusted, and it can flexibly respond to changes in ambient light, so that the inverter can better control the photovoltaic array to operate at the maximum power point when there is no power limit demand. It can achieve similar performance to the traditional algorithm in terms of extracting maximum power from the photovoltaic panel, and can obtain faster dynamic characteristics, thereby improving the power generation efficiency under steady-state conditions and the power tracking dynamic performance under transient conditions.

[0032] Furthermore, determining the first target step size and the first step size coefficient of the inverter based on the bidirectional disturbance algorithm, the current power, the set step size threshold, and the set step size coefficient includes:

[0033] Based on a bidirectional perturbation algorithm and a set step size threshold, controlling the inverter to perturb in a first direction, and obtaining a first power and a first light intensity after the perturbation;

[0034] determining a first power change difference of the inverter based on the first power and the current power;

[0035] Based on a bidirectional perturbation algorithm and a set step size threshold, controlling the inverter to perturb in a second direction, and obtaining a second power and a second light intensity after the perturbation;

[0036] determining a second power change difference of the inverter based on the second power and the current power;

[0037] If the first power change difference is greater than the second power change difference, determining that the set step threshold of the inverter is a positive value;

[0038] If the first power change difference is not greater than the second power change difference, determining that the set step threshold of the inverter is a negative value;

[0039] determining a first target step size of the inverter based on a set step size threshold of the inverter;

[0040] Determining a state control mode of a first operating mode of the inverter based on the first light intensity and the second light intensity, wherein the state control mode of the first operating mode is a dynamic MPPT mode or a steady-state MPPT mode, wherein the dynamic MPPT mode represents an MPPT mode in an unstable environment, and the steady-state MPPT mode represents an MPPT mode in a stable environment;

[0041] A first step coefficient of the inverter is determined based on the state control mode of the first operation mode and a set step coefficient.

[0042] The beneficial effects of adopting the above further scheme are: using a bidirectional perturbation algorithm to perform perturbations in two directions and comparing the power change differences, the positive and negative values of the set step size threshold can be accurately determined, thereby reasonably determining the first target step size; determining the state control mode of the inverter in the first operating mode according to the first light intensity and the second light intensity, and further accurately determining the first step size coefficient, which helps to adaptively adjust the voltage step size according to different environmental stability levels in the MPPT mode, achieve efficient tracking of the maximum power point of the photovoltaic array, and improve the power generation efficiency of the photovoltaic system when there is no power limit demand.

[0043] Furthermore, the determining of the first step length coefficient of the inverter based on the state control mode of the first operating mode includes:

[0044] If the state control mode of the first operating mode is a dynamic MPPT mode, determining the first step length coefficient of the inverter as a first target step length coefficient;

[0045] If the state control mode of the first operation mode is a steady-state MPPT mode, the first step coefficient of the inverter is determined to be a second target step coefficient, and the second target step coefficient is smaller than the first target step coefficient.

[0046] The beneficial effect of adopting the above further scheme is: when in the dynamic MPPT mode, the first step length coefficient is determined to be the first target step length coefficient, and when in the steady-state MPPT mode, the first step length coefficient is determined to be the smaller second target step length coefficient. The step length coefficient can be flexibly adjusted according to the environmental conditions, so that the inverter can better adapt to environmental changes. When the environment is unstable, the step length coefficient is increased to speed up the response speed, and when the environment is stable, the step length coefficient is reduced to improve the control accuracy, thereby improving the dynamic performance and steady-state performance of the inverter and achieving more flexible and effective active power control.

[0047] Further, if the current operating mode of the inverter is the second operating mode, determining the voltage step size of the inverter based on the current operating mode of the inverter, the current power, and a preset voltage step size adjustment rule includes:

[0048] calculating a second target step size of the inverter based on the second operating mode of the inverter, the current power, and a set reference power threshold;

[0049] Determining a state control mode of the second operating mode based on the power difference and a second set difference threshold, where the state control mode of the second operating mode is a steady-state flexible power control mode or a dynamic flexible power control mode, the steady-state flexible power control mode represents a flexible power control mode with stable power, and the dynamic flexible power control mode represents a flexible power control mode with unstable power, and the second set difference threshold is less than the first set difference threshold;

[0050] determining a second step coefficient of the inverter based on a state control mode of the second operating mode;

[0051] A voltage step size of the inverter is determined based on a second target step size of the inverter and the second step size coefficient.

[0052] The beneficial effects of adopting the above further scheme are: according to the fact that the inverter is currently in the second operating mode (flexible power control mode), the second target step size is calculated in combination with the current power and the set reference power threshold, so that the step size calculation can fit the power control requirements under this mode; the state control mode (steady-state or dynamic flexible power control mode) of the second operating mode is determined based on the power difference and the second set difference threshold, which can more accurately reflect the power stability; the second step size coefficient is determined according to the state control mode, and the step size can be flexibly adjusted according to the degree of power stability; finally, the voltage step size is determined based on the second target step size and the second step size coefficient, which can realize adaptive adjustment of the inverter voltage step size in the flexible power control mode, meet the precise control of the photovoltaic array operating point deviating from the maximum power point when there is a power limitation requirement, and improve the flexibility and accuracy of the inverter's active power control under different working conditions.

[0053] Further, determining the state control mode of the second operating mode based on the power difference and a second set difference threshold includes:

[0054] If the power difference is greater than a second set difference threshold, determining that the state control mode of the second operating mode is a steady-state flexible power control mode;

[0055] If the power difference is not greater than the second set difference threshold, determining whether the power change rate at the current moment is greater than the set second set power change rate threshold, and the second set power change rate threshold is greater than the first set power change rate threshold;

[0056] If the power change rate at the current moment is greater than the second set power change rate threshold, determining that the state control mode of the second operating mode is the dynamic flexible power control mode;

[0057] If the power change rate at the current moment is not greater than the second set power change rate threshold, determining whether the power difference is greater than a third set difference threshold, and the third set difference threshold is less than the second set difference threshold;

[0058] If the power difference is greater than a third set difference threshold, determining that the state control mode of the second operating mode is a dynamic flexible power control mode;

[0059] Otherwise, it is determined that the state control mode of the second operating mode is the steady-state flexible power control mode.

[0060] The beneficial effect of adopting the above further scheme is: based on the comparison of the power difference with the second set difference threshold, and under specific conditions, combined with the comparison of the power change rate at the current moment with the second set power change rate threshold, and the power difference with the third set difference threshold, it is possible to accurately distinguish whether the second operating mode (flexible power control mode) is in steady state or dynamic, providing a basis for the subsequent determination of the appropriate second step coefficient, so that the voltage step size of the inverter can be determined more accurately, more flexible active power control can be achieved, and the power generation efficiency under steady-state conditions and the power tracking dynamic performance under transient conditions can be improved.

[0061] Furthermore, determining a second step coefficient of the inverter based on the state control mode includes:

[0062] If the state control mode of the second operation mode of the inverter is a steady-state flexible power control mode, determining the second step size coefficient of the inverter to be a third target step size coefficient;

[0063] If the state control mode of the second operation mode of the inverter is a dynamic flexible power control mode, the second step coefficient of the inverter is determined to be a fourth target step coefficient, and the third target step coefficient is smaller than the fourth target step coefficient.

[0064] The beneficial effects of adopting the above-mentioned further scheme are: the corresponding second step coefficient is determined according to the state control mode of the second operating mode of the inverter. When in the steady-state flexible power control mode, it is determined as a smaller third target step coefficient, which can ensure fine voltage step adjustment under the power stable state and achieve more accurate power control; when in the dynamic flexible power control mode, it is determined as a larger fourth target step coefficient, which can quickly adjust the voltage step when the power is unstable, thereby improving the system response speed. Combined with the overall scheme, the voltage step step can be flexibly adjusted, so that the inverter can achieve efficient and adaptive active power control under different working conditions.

[0065] In a second aspect, the present application provides an inverter active power adaptive control device, which adopts the following technical solution:

[0066] An inverter active power adaptive control device, comprising:

[0067] An acquisition module is used to obtain parameter information of the photovoltaic array output at the current moment, wherein the photovoltaic array is composed of a plurality of photovoltaic modules, and the parameter information includes the current voltage and the current current;

[0068] a calculation module, configured to calculate, based on the current voltage and the current current, the current power and the power change rate of the photovoltaic array at the current moment, wherein the power change rate is used to characterize the dynamic shift trend of the photovoltaic array operating point on the power-voltage curve;

[0069] an operating mode determination module, configured to determine a current operating mode of the inverter at a current moment based on the current power, the power change rate, an initial operating mode of the inverter, and a preset operating mode switching condition, wherein the initial operating mode is the operating mode of the inverter at a moment before the current moment, and the current operating mode is a first operating mode or a second operating mode, wherein the first operating mode is an MPPT mode for controlling the photovoltaic array to operate at a maximum power point when there is no power limitation requirement, and the second operating mode is a flexible power control mode for controlling the operating point of the photovoltaic array to deviate from the maximum power point when there is a power limitation requirement;

[0070] a step size determination module, configured to determine a voltage step size of the inverter based on a current operating mode and current power of the inverter and a preset voltage step size adjustment rule;

[0071] a reference voltage determination module for determining a reference voltage of the inverter at a current moment based on a voltage step size and an initial reference voltage of the inverter, and generating an active power control signal based on the current reference voltage and a current operating mode to adjust an operating point of the photovoltaic array, wherein the initial reference voltage is the reference voltage of the inverter at a moment before the current moment.

[0072] Additional aspects and advantages of the present application will be given in part in the following description, which will become apparent from the following description, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 A schematic flow chart of an inverter active power adaptive control method provided by one embodiment of the present invention;

[0074] Figure 2 A schematic diagram of a flow chart of an inverter active power adaptive control device provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0075] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0076] In this document, the term "and / or" simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document, unless otherwise specified, generally indicates an "or" relationship between the related objects.

[0077] An embodiment of the present application provides an inverter active power adaptive control method, which can be executed by an electronic device. The electronic device can be an inverter, but is not limited thereto.

[0078] like Figure 1 As shown, an inverter active power adaptive control method mainly includes:

[0079] S1, obtaining the parameter information of the photovoltaic array output at the current moment. The photovoltaic array is composed of multiple photovoltaic modules, and the parameter information includes the current voltage and current current;

[0080] In the embodiments of the present application, a photovoltaic array is generally composed of a plurality of photovoltaic modules, such as monocrystalline silicon photovoltaic modules or polycrystalline silicon photovoltaic modules. The detection device may utilize a high-precision voltage sensor and current sensor. The voltage sensor may be used to collect the current voltage output by the photovoltaic array in real time, while the current sensor may be used to collect the current current output by the photovoltaic array in real time.

[0081] S2, based on the current voltage and current current, calculates the current power and power change rate of the PV array at the current moment. The power change rate is used to characterize the dynamic offset trend of the PV array operating point on the power-voltage curve;

[0082] In the embodiment of the present application, the current power is calculated as follows:

[0083] P = V × I;

[0084] Where P is the current power, V is the current voltage, and I is the current current.

[0085] The power rate of change is used to characterize the dynamic shift of the PV array operating point on the power-voltage curve. It is calculated by calculating the ratio of the power difference between adjacent sampling points to the time interval. For example, a large power rate of change within a certain time interval indicates that the PV array operating point is shifting rapidly on the power-voltage curve.

[0086] First, the power change is determined based on the current power and the power at the previous moment.

[0087] Secondly, based on the current voltage and the voltage at the previous moment, the voltage change is determined;

[0088] Finally, based on the power change amount, the voltage change amount and a preset power change rate formula, the power change rate of the photovoltaic array at the current moment is determined.

[0089] Among them, the preset power change rate formula is:

[0090] PV = ΔP / ΔV;

[0091] Where PV is the power change rate, ΔP is the power change, and ΔV is the voltage change.

[0092] S3, determining the current operating mode of the inverter at the current moment based on the current power, the power change rate, the initial operating mode of the inverter and the preset operating mode switching condition;

[0093] The initial operating mode is the operating mode of the inverter at the moment before the current moment. The current operating mode is the first operating mode or the second operating mode. The first operating mode is the MPPT mode that controls the photovoltaic array to operate at the maximum power point when there is no power limitation requirement. The second operating mode is the flexible power control mode that controls the operating point of the photovoltaic array to deviate from the maximum power point when there is a power limitation requirement.

[0094] In the embodiment of the present application, the current operating mode of the inverter at the current moment is determined based on the current power, the power change rate, the initial operating mode of the inverter, and the preset operating mode switching condition, including:

[0095] If the initial operation mode of the inverter is the first operation mode, obtaining a set reference power threshold at the current moment, wherein the set reference power threshold may be determined according to actual demand of the power grid or setting of the user;

[0096] Determining a power difference based on the current power and a set reference power threshold at a current moment;

[0097] When the power difference is greater than a first set difference threshold, determining that the current operating mode of the inverter at the current moment is the second operating mode;

[0098] or, when the first set reference power threshold at the current moment is inconsistent with the first set reference power threshold at the previous moment, determining that the current operating mode of the inverter at the current moment is the second operating mode;

[0099] Otherwise, it is determined that the current operating mode of the inverter at the current moment is the first operating mode.

[0100] If the initial operation mode of the inverter is the second operation mode, when the power difference is not greater than the first set difference threshold and the power change rate at the current moment is less than the first set power change rate threshold, determining that the current operation mode of the inverter at the current moment is the first operation mode;

[0101] Otherwise, it is determined that the current operating mode of the inverter at the current moment is the second operating mode.

[0102] In the embodiment of the present application, when the difference between the current power and the set power reference threshold is less than the first set difference threshold and the calculated working point power change rate ΔP / ΔV at this time is close to 0, the flexible power control mode ends and switches to the MPPT mode.

[0103] When the inverter initially operates in the first operating mode (MPPT mode), it decides whether to switch to the second operating mode (flexible power control mode) by comparing the difference between the current power and the set reference power threshold, or judging whether the set reference power threshold has changed. This realizes adaptive switching of the inverter operating mode under different power requirements, which helps the inverter improve power generation efficiency and power tracking performance while meeting different power limit requirements.

[0104] By accurately judging whether to switch to the first operating mode when the initial operating mode of the inverter is the second operating mode based on the difference between the current power and the set reference power threshold and the power change rate at the current moment, flexible switching between the MPPT mode and the flexible power control mode is achieved, which improves the adaptability and flexibility of the inverter's active power control and can better meet different power control requirements.

[0105] S4, determining a voltage step size of the inverter based on a current operating mode and current power of the inverter and a preset voltage step size adjustment rule;

[0106] In the embodiment of the present application, the calculation formula of the voltage step length of the inverter is:

[0107] V step =k*V preset ;

[0108] Where k is the power control step coefficient under different operating modes, the step coefficient is the first step coefficient or the second step coefficient, V presetis the target step length in different operating modes, and the target step length is the first target step length or the second target step length.

[0109] In an embodiment of the present application, if the current operating mode of the inverter is the first operating mode, determining the voltage step size of the inverter based on the current operating mode of the inverter, the current power, and a preset voltage step size adjustment rule includes:

[0110] S41, determining a set step size threshold and a set step size coefficient of the inverter based on a first operation mode of the inverter;

[0111] S42, determining a first target step size and a first step size coefficient of the inverter based on a bidirectional disturbance algorithm, current power, a set step size threshold, and a set step size coefficient;

[0112] In the embodiment of the present application, S42 specifically includes:

[0113] S421, based on a bidirectional perturbation algorithm and a set step size threshold, controlling the inverter to perturb in a first direction, and obtaining a first power and a first light intensity after the perturbation;

[0114] S422, determining a first power change difference of the inverter based on the first power and the current power;

[0115] S423, based on the bidirectional perturbation algorithm and the set step size threshold, controlling the inverter to perturb in the second direction, and obtaining a second power and a second light intensity after the perturbation;

[0116] S424, determining a second power change difference of the inverter based on the second power and the current power;

[0117] S425, if the first power change difference is greater than the second power change difference, determining that the set step threshold of the inverter is a positive value;

[0118] S426, if the first power change difference is not greater than the second power change difference, determining that the set step threshold of the inverter is a negative value;

[0119] S427, determining a first target step size of the inverter based on a set step size threshold of the inverter;

[0120] S428, determining a state control mode of a first operating mode of the inverter based on the first light intensity and the second light intensity, where the state control mode of the first operating mode is a dynamic MPPT mode or a steady-state MPPT mode, where the dynamic MPPT mode represents an MPPT mode in an unstable environment, and the steady-state MPPT mode represents an MPPT mode in a stable environment;

[0121] S429 , determining a first step coefficient of the inverter based on the state control mode of the first operation mode and the set step coefficient.

[0122] S43 : Determine a voltage step size of the inverter based on the first target step size and the first step size coefficient.

[0123] In the embodiment of the present application, S43 specifically includes:

[0124] If the state control mode of the first operating mode is the dynamic MPPT mode, determining the first step length coefficient of the inverter as the first target step length coefficient;

[0125] If the state control mode of the first operation mode is the steady-state MPPT mode, the first step length coefficient of the inverter is determined to be the second target step length coefficient, and the second target step length coefficient is smaller than the first target step length coefficient.

[0126] The following is an example to illustrate step 42. The current power is recorded as P0. In step 1, the inverter is controlled to disturb in the positive direction first, and the step threshold is set to V preset , record the power at this time as P1, the power change of this disturbance is ΔP1; the second step controls the inverter to disturb in the negative direction first, with a step length of -V preset , record the power at this time as P2, and the power change of this disturbance is ΔP2; if ΔP1>ΔP2, it means the direction of step 1 is correct, and the disturbance is repeated in the direction of step 1; otherwise, the direction of step 2 is correct, and the disturbance ends after another disturbance in the direction of step 2; during the disturbance process, the power change ΔP caused by the light intensity is x =(P0+P2) / 2-P0, if the detected light changes, that is, when ΔP x When the disturbance is greater than a certain threshold, the system enters the dynamic MPPT mode and increases the voltage step coefficient k=2; if the disturbance tends to be stable, the system enters the steady-state MPPT mode and decreases the voltage step coefficient k=1.

[0127] When the inverter is in the first operating mode (MPPT mode), a bidirectional perturbation algorithm is used in combination with a set step threshold and a set step coefficient to determine the first target step size and the first step coefficient, thereby determining the voltage step size. The voltage step size can be adjusted dynamically, and the inverter can flexibly respond to changes in ambient light, so that the inverter can better control the photovoltaic array to operate at the maximum power point when there is no power limit requirement.

[0128] In an embodiment of the present application, if the current operating mode of the inverter is the second operating mode, determining the voltage step size of the inverter based on the current operating mode of the inverter, the current power, and a preset voltage step size adjustment rule includes:

[0129] S44, calculating a second target step size of the inverter based on the second operating mode of the inverter, the current power, and the set reference power threshold;

[0130] In the embodiment of the present application, the calculation formula of the second target step length is: V preset =|ΔP * |;

[0131] ΔP * =P now -P set ;

[0132] Among them, V preset is the second target step length, P now is the current power, P set To set the reference power threshold.

[0133] S45, determining a state control mode of the second operating mode based on the power difference and the second set difference threshold, where the state control mode of the second operating mode is a steady-state flexible power control mode or a dynamic flexible power control mode, where the steady-state flexible power control mode represents a flexible power control mode with stable power, and the dynamic flexible power control mode represents a flexible power control mode with unstable power, and the second set difference threshold is less than the first set difference threshold;

[0134] S46, determining a second step coefficient of the inverter based on the state control mode of the second operation mode;

[0135] In the embodiment of the present application, determining the state control mode of the second operating mode based on the power difference and the second set difference threshold includes:

[0136] If the power difference is greater than a second set difference threshold, determining that the state control mode of the second operating mode is a steady-state flexible power control mode;

[0137] If the power difference is not greater than the second set difference threshold, determining whether the power change rate at the current moment is greater than the set second set power change rate threshold, and the second set power change rate threshold is greater than the first set power change rate threshold;

[0138] If the power change rate at the current moment is greater than the second set power change rate threshold, determining that the state control mode of the second operating mode is the dynamic flexible power control mode;

[0139] If the power change rate at the current moment is not greater than the second set power change rate threshold, then determining whether the power difference is greater than a third set difference threshold, and the third set difference threshold is less than the second set difference threshold;

[0140] If the power difference is greater than a third set difference threshold, determining that the state control mode of the second operating mode is a dynamic flexible power control mode;

[0141] Otherwise, it is determined that the state control mode of the second operation mode is the steady-state flexible power control mode.

[0142] In the embodiment of the present application, the third set difference threshold is set to 0. By judging whether the absolute value of the power difference (denoted as |ΔP * |) exceeds the second set difference threshold (denoted as ΔP th2 ), the step coefficient of the steady-state or dynamic flexible power control mode is selected. If |ΔP * |<ΔP th2 , then enter the steady-state flexible power control mode; if |ΔP * |≥ΔP th2 , then it is necessary to judge based on the absolute value of the slope of the PV curve at the current working position |ΔP / ΔV|, that is, the power change rate at the current moment. If |ΔP / ΔV|>Thr, it means that the current is operating on both sides of the PV curve, and enter the dynamic flexible power control mode. If |ΔP / ΔV|<Thr, the current is operating near the maximum power point, where Thr is the second set power change rate threshold, and further judgment is required. If ΔP * >0, then enter the dynamic flexible power control mode, otherwise, enter the steady-state flexible power control mode.

[0143] S47. Determine the voltage step of the inverter based on the second target step and the second step coefficient of the inverter.

[0144] In the embodiment of the present application, determining the second step coefficient of the inverter based on the state control mode includes:

[0145] If the state control mode of the second operating mode of the inverter is the steady-state flexible power control mode, then determine the second step coefficient of the inverter as the third target step coefficient;

[0146] If the state control mode of the second operating mode of the inverter is the dynamic flexible power control mode, then determine the second step coefficient of the inverter as the fourth target step coefficient, and the third target step coefficient is less than the fourth target step coefficient.

[0147] In the embodiment of the present application, the corresponding second step coefficient is determined according to the state control mode of the second operating mode of the inverter. When in the steady-state flexible power control mode, it is determined as the smaller third target step coefficient, which can ensure fine voltage step adjustment in the power stable state and achieve more accurate power control; when in the dynamic flexible power control mode, it is determined as the larger fourth target step coefficient, which can quickly adjust the voltage step when the power is unstable and improve the system response speed. Combining the overall scheme, the voltage step can be flexibly adjusted, enabling the inverter to achieve efficient adaptive active power control under different working conditions.

[0148] According to the fact that the inverter is currently in the second operating mode (flexible power control mode), the second target step size is calculated in combination with the current power and the set reference power threshold, so that the step size calculation can fit the power control requirements under this mode; the state control mode (steady-state or dynamic flexible power control mode) of the second operating mode is determined based on the power difference and the second set difference threshold, which can more accurately reflect the power stability; the second step size coefficient is determined according to the state control mode, and the step size can be flexibly adjusted according to the degree of power stability; finally, the voltage step size is determined based on the second target step size and the second step size coefficient, which can realize adaptive adjustment of the inverter voltage step size in the flexible power control mode, meet the precise control of the deviation of the photovoltaic array operating point from the maximum power point when there is a power limitation requirement, and improve the flexibility and accuracy of the active power control of the inverter under different working conditions.

[0149] S5, based on the voltage step size and initial reference voltage of the inverter, determine the reference voltage of the inverter at the current moment, and generate an active power control signal based on the reference voltage at the current moment and the current operating mode to adjust the operating point of the photovoltaic array, where the initial reference voltage is the reference voltage of the inverter at the previous moment before the current moment.

[0150] In the embodiment of the present application, the calculation formula of the reference voltage is:

[0151] V ref =V ref-old +V step ;

[0152] Among them, V ref is the reference voltage at the current moment, V ref-old is the reference voltage of the previous moment before the current moment, V step is the voltage step length.

[0153] The inverter adjusts its own operating state according to the generated active power control signal, thereby adjusting the operating point of the photovoltaic array and achieving precise control of the active power.

[0154] This method obtains the parameter information of the photovoltaic array, calculates the current power and power change rate, and determines the current operating mode of the inverter. It can also determine the voltage step size and reference voltage based on the current operating mode and related rules, and then generate an active power control signal to adjust the array operating point. It can adaptively combine the MPPT mode and the flexible power control mode, flexibly adjust the voltage step size, and achieve more flexible active power control, meet the fast dynamic response and steady-state performance of power control, and can adapt to rapidly changing grid conditions.

[0155] Figure 2 A structural diagram of an inverter active power adaptive control device 200 is shown.

[0156] like Figure 2 As shown, an inverter active power adaptive control device 200 mainly includes:

[0157] The acquisition module 201 is used to obtain parameter information of the photovoltaic array output at the current moment. The photovoltaic array is composed of multiple photovoltaic modules. The parameter information includes the current voltage and current current.

[0158] A calculation module 202 is configured to calculate the current power and power change rate of the photovoltaic array at the current moment based on the current voltage and the current current, where the power change rate is used to characterize the dynamic shift trend of the photovoltaic array operating point on the power-voltage curve;

[0159] An operating mode determination module 203 is configured to determine the current operating mode of the inverter at the current moment based on the current power, the power change rate, the initial operating mode of the inverter, and a preset operating mode switching condition. The initial operating mode is the operating mode of the inverter at the moment before the current moment. The current operating mode is either the first operating mode or the second operating mode. The first operating mode is an MPPT mode that controls the photovoltaic array to operate at a maximum power point when there is no power limitation requirement. The second operating mode is a flexible power control mode that controls the operating point of the photovoltaic array to deviate from the maximum power point when there is a power limitation requirement.

[0160] a step size determination module 204 for determining a voltage step size of the inverter based on a current operating mode of the inverter, a current power, and a preset voltage step size adjustment rule;

[0161] The reference voltage determination module 205 is used to determine the reference voltage of the inverter at a current moment based on the voltage step size and the initial reference voltage of the inverter, and to generate an active power control signal based on the reference voltage at the current moment and the current operating mode to adjust the operating point of the photovoltaic array, where the initial reference voltage is the reference voltage of the inverter at a moment before the current moment.

[0162] The modules involved in the embodiments of the present invention may be implemented in software or hardware, wherein the name of a module does not necessarily limit the module itself.

[0163] In one example, the module in any of the above devices can be one or more integrated circuits configured to implement the above methods, such as: one or more application specific integrated circuits (ASICs), or one or more digital signal processors (DSPs), or one or more field programmable gate arrays (FPGAs), or a combination of at least two of these integrated circuit forms.

[0164] For another example, when the modules in the device can be implemented in the form of a processing element scheduling program, the processing element can be a general-purpose processor, such as a central processing unit (CPU) or other processor that can call programs. For another example, these modules can be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0165] Various objects such as various messages / information / equipment / network elements / systems / devices / actions / operations / processes / concepts that may appear in this application are named. It can be understood that these specific names do not constitute a limitation on the relevant objects. The names assigned may change with factors such as scenarios, contexts or usage habits. The understanding of the technical meaning of the technical terms in this application should be mainly determined from the functions and technical effects embodied / executed in the technical solutions.

[0166] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and modules described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0167] Those skilled in the art will appreciate that the modules and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0168] The terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0169] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of application involved in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the aforementioned application concept. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions applied for in this application.

Claims

1. A method for adaptively controlling active power of an inverter, characterized in that: include: Obtaining parameter information of a photovoltaic array output at a current moment, the photovoltaic array being composed of a plurality of photovoltaic modules, the parameter information including current voltage and current current; Calculating, based on the current voltage and the current current, the current power and the power change rate of the photovoltaic array at the current moment, wherein the power change rate is used to characterize the dynamic shift trend of the photovoltaic array operating point on the power-voltage curve; Determining a current operating mode of the inverter at a current moment based on the current power, the power change rate, the initial operating mode of the inverter, and a preset operating mode switching condition, wherein the initial operating mode is the operating mode of the inverter at a moment before the current moment, and the current operating mode is a first operating mode or a second operating mode, wherein the first operating mode is an MPPT mode for controlling the photovoltaic array to operate at a maximum power point when there is no power limitation requirement, and the second operating mode is a flexible power control mode for controlling the operating point of the photovoltaic array to deviate from the maximum power point when there is a power limitation requirement; Determining a voltage step size of the inverter based on a current operating mode, current power, and a preset voltage step size adjustment rule of the inverter; Based on the voltage step size and initial reference voltage of the inverter, a reference voltage of the inverter at a current moment is determined, and based on the reference voltage at the current moment and the current operating mode, an active power control signal is generated to adjust the operating point of the photovoltaic array, where the initial reference voltage is the reference voltage of the inverter at a moment before the current moment.

2. The method for adaptively controlling active power of an inverter according to claim 1, wherein: The determining the current operating mode of the inverter at a current moment based on the current power, the power change rate, the initial operating mode of the inverter, and a preset operating mode switching condition includes: If the initial operation mode of the inverter is the first operation mode, obtaining a set reference power threshold at the current moment; Determining a power difference based on the current power and a set reference power threshold at a current moment; When the power difference is greater than a first set difference threshold, determining that the current operating mode of the inverter at the current moment is the second operating mode; or, when the set reference power threshold at the current moment is inconsistent with the set reference power threshold at the previous moment before the current moment, determining that the current operating mode of the inverter at the current moment is the second operating mode; Otherwise, it is determined that the current operating mode of the inverter at the current moment is the first operating mode.

3. The method for adaptively controlling active power of an inverter according to claim 2, wherein: The determining of the current operating mode of the inverter at a current moment based on the current power, the power change rate, the initial operating mode of the inverter, and a preset operating mode switching condition further includes: If the initial operation mode of the inverter is the second operation mode, when the power difference is not greater than a first set difference threshold and the power change rate at the current moment is less than the first set power change rate threshold, determining that the current operation mode of the inverter at the current moment is the first operation mode; Otherwise, it is determined that the current operating mode of the inverter at the current moment is the second operating mode.

4. The method for adaptively controlling active power of an inverter according to claim 3, wherein: If the current operating mode of the inverter is the first operating mode, determining the voltage step size of the inverter based on the current operating mode of the inverter, the current power, and a preset voltage step size adjustment rule includes: determining a set step size threshold and a set step size coefficient of the inverter based on a first operating mode of the inverter; Determining a first target step size and a first step size coefficient of the inverter based on a bidirectional disturbance algorithm, current power, a set step size threshold, and a set step size coefficient; A voltage step size of the inverter is determined based on the first target step size and the first step size coefficient.

5. The method for adaptively controlling active power of an inverter according to claim 4, wherein: The determining of the first target step size and the first step size coefficient of the inverter based on the bidirectional disturbance algorithm, the current power, the set step size threshold, and the set step size coefficient includes: Based on a bidirectional perturbation algorithm and a set step size threshold, controlling the inverter to perturb in a first direction, and obtaining a first power and a first light intensity after the perturbation; determining a first power change difference of the inverter based on the first power and the current power; Based on a bidirectional perturbation algorithm and a set step size threshold, controlling the inverter to perturb in a second direction, and obtaining a second power and a second light intensity after the perturbation; determining a second power change difference of the inverter based on the second power and the current power; If the first power change difference is greater than the second power change difference, determining that the set step threshold of the inverter is a positive value; If the first power change difference is not greater than the second power change difference, determining that the set step threshold of the inverter is a negative value; determining a first target step size of the inverter based on a set step size threshold of the inverter; Determining a state control mode of a first operating mode of the inverter based on the first light intensity and the second light intensity, wherein the state control mode of the first operating mode is a dynamic MPPT mode or a steady-state MPPT mode, wherein the dynamic MPPT mode represents an MPPT mode in an unstable environment, and the steady-state MPPT mode represents an MPPT mode in a stable environment; A first step coefficient of the inverter is determined based on the state control mode of the first operation mode and a set step coefficient.

6. The method for adaptively controlling active power of an inverter according to claim 5, wherein: The determining of the first step length coefficient of the inverter based on the state control mode of the first operating mode includes: If the state control mode of the first operating mode is a dynamic MPPT mode, determining the first step length coefficient of the inverter as a first target step length coefficient; If the state control mode of the first operation mode is a steady-state MPPT mode, the first step coefficient of the inverter is determined to be a second target step coefficient, and the second target step coefficient is smaller than the first target step coefficient.

7. The method for adaptively controlling active power of an inverter according to claim 3, wherein: If the current operating mode of the inverter is the second operating mode, determining the voltage step size of the inverter based on the current operating mode of the inverter, the current power, and a preset voltage step size adjustment rule includes: calculating a second target step size of the inverter based on a second operating mode of the inverter, the current power, and a set reference power threshold; Determining a state control mode of the second operating mode based on the power difference and a second set difference threshold, where the state control mode of the second operating mode is a steady-state flexible power control mode or a dynamic flexible power control mode, the steady-state flexible power control mode represents a flexible power control mode with stable power, and the dynamic flexible power control mode represents a flexible power control mode with unstable power, and the second set difference threshold is less than the first set difference threshold; determining a second step coefficient of the inverter based on a state control mode of the second operating mode; A voltage step size of the inverter is determined based on a second target step size of the inverter and the second step size coefficient.

8. The method for adaptively controlling active power of an inverter according to claim 7, wherein: The determining the state control mode of the second operating mode based on the power difference and the second set difference threshold includes: If the power difference is greater than a second set difference threshold, determining that the state control mode of the second operating mode is a steady-state flexible power control mode; If the power difference is not greater than the second set difference threshold, determining whether the power change rate at the current moment is greater than the set second set power change rate threshold, and the second set power change rate threshold is greater than the first set power change rate threshold; If the power change rate at the current moment is greater than the second set power change rate threshold, determining that the state control mode of the second operating mode is the dynamic flexible power control mode; If the power change rate at the current moment is not greater than the second set power change rate threshold, determining whether the power difference is greater than a third set difference threshold, and the third set difference threshold is less than the second set difference threshold; If the power difference is greater than a third set difference threshold, determining that the state control mode of the second operating mode is a dynamic flexible power control mode; Otherwise, it is determined that the state control mode of the second operating mode is the steady-state flexible power control mode.

9. The method for adaptively controlling active power of an inverter according to claim 7, wherein: The determining, based on the state control mode, a second step coefficient of the inverter includes: If the state control mode of the second operation mode of the inverter is a steady-state flexible power control mode, determining the second step size coefficient of the inverter to be a third target step size coefficient; If the state control mode of the second operation mode of the inverter is a dynamic flexible power control mode, the second step coefficient of the inverter is determined to be a fourth target step coefficient, and the third target step coefficient is smaller than the fourth target step coefficient.

10. An inverter active power adaptive control device, characterized in that: include: An acquisition module is used to obtain parameter information of the photovoltaic array output at the current moment, wherein the photovoltaic array is composed of a plurality of photovoltaic modules, and the parameter information includes the current voltage and the current current; a calculation module, configured to calculate, based on the current voltage and the current current, the current power and the power change rate of the photovoltaic array at the current moment, wherein the power change rate is used to characterize the dynamic shift trend of the photovoltaic array operating point on the power-voltage curve; an operating mode determination module, configured to determine a current operating mode of the inverter at a current moment based on the current power, the power change rate, an initial operating mode of the inverter, and a preset operating mode switching condition, wherein the initial operating mode is the operating mode of the inverter at a moment before the current moment, and the current operating mode is a first operating mode or a second operating mode, wherein the first operating mode is an MPPT mode for controlling the photovoltaic array to operate at a maximum power point when there is no power limitation requirement, and the second operating mode is a flexible power control mode for controlling the operating point of the photovoltaic array to deviate from the maximum power point when there is a power limitation requirement; a step size determination module, configured to determine a voltage step size of the inverter based on a current operating mode and current power of the inverter and a preset voltage step size adjustment rule; a reference voltage determination module for determining a reference voltage of the inverter at a current moment based on a voltage step size and an initial reference voltage of the inverter, and generating an active power control signal based on the current reference voltage and a current operating mode to adjust an operating point of the photovoltaic array, wherein the initial reference voltage is the reference voltage of the inverter at a moment before the current moment.

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