Inverter control method and device, control equipment and inverter

Abstract

The invention provides a control method and device of an inverter, control equipment and the inverter. The method comprises the following steps: acquiring real-time voltage of a power grid; when the real-time voltage is equal to a first voltage threshold value, first positive reactive power output by the inverter is collected, and the positive reactive power output by the inverter is controlled to be kept as the first positive reactive power; and when the real-time voltage is equal to the second voltage threshold value, collecting first negative reactive power output by the inverter, and controlling the negative reactive power output by the inverter to be kept as the first negative reactive power. According to the invention, the voltage can be controlled not to be increased before the overvoltage protection is triggered, the inverter can maintain the maximum positive reactive power for output without causing waste, the voltage can be controlled not to be reduced before the undervoltage protection is triggered, and the inverter can maintain the maximum negative reactive power for output without causing waste. Waste is not caused, and the situation that overvoltage protection or undervoltage protection is triggered for a long time does not occur.

Description

Technical Field

[0001] The present invention relates to the technical field of power grids, and particularly to a control method, device, control equipment and inverter for an inverter. Background Art

[0002] A power generation system can convert other energy sources into electrical energy for power station dispatching or supplying loads. For example, in solar photovoltaic power generation, the photovoltaic effect of semiconductor materials is utilized. When sunlight shines on the photovoltaic panels, photons interact with electrons in the semiconductors, prompting the electrons to move directionally, thereby generating direct current. The direct current is then converted into alternating current by an inverter for transmission to the power grid or for local load use.

[0003] However, when a small-scale power generation system is connected to the end of a distribution network, it may cause the local network where it is connected to form a weak grid. Due to the small short-circuit capacity of the weak grid, when the load changes or distributed power sources are connected, the voltage fluctuates greatly, and voltage instability is likely to occur, causing the grid voltage to rise or the grid voltage to drop beyond the normal range, triggering overvoltage protection or undervoltage protection, making the power generation system (such as the inverter it contains) unable to be put into use. Moreover, if the grid voltage continuously triggers overvoltage protection or undervoltage protection for a long time, it is easy to cause damage to the equipment in the power generation system, and even the situation of explosion of the machine. Summary of the Invention

[0004] Embodiments of the present invention provide a control method, device, control equipment and inverter for an inverter, so as to solve the problems that the voltage of the power grid fluctuates greatly, which is likely to cause overvoltage protection or undervoltage protection, making the power generation system unable to be put into use, and even easily causing damage to the equipment in the power generation system, and even explosion of the machine.

[0005] In a first aspect, embodiments of the present invention provide a control method for an inverter, including:

[0006] Obtaining the real-time voltage of the power grid;

[0007] When the real-time voltage is equal to a first voltage threshold, collecting the first positive reactive power output by the inverter, and controlling the positive reactive power output by the inverter to remain the first positive reactive power; the first voltage threshold is determined according to a preset overvoltage protection voltage, and the first voltage threshold is less than or equal to the preset overvoltage protection voltage;

[0008] When the real-time voltage is equal to a second voltage threshold, collecting the first negative reactive power output by the inverter, and controlling the negative reactive power output by the inverter to remain the first negative reactive power; the second voltage threshold is determined according to a preset undervoltage protection voltage, and the second voltage threshold is greater than or equal to the preset undervoltage protection voltage; the first voltage threshold is greater than the second voltage threshold.

[0009] In a possible implementation, before collecting the first positive reactive power output by the inverter when the real-time voltage is equal to the first voltage threshold, it further includes:

[0010] When the real-time voltage is less than or equal to the first voltage threshold and greater than the third voltage threshold, control the change rate of the positive reactive power output by the inverter to be reduced to the first preset reactive power change rate;

[0011] Wherein, when the change rate of the positive reactive power output by the inverter is the first preset reactive power change rate, the positive reactive power output by the inverter is collected once, and the increment of the grid voltage is less than or equal to the first change threshold.

[0012] In a possible implementation, before collecting the first positive reactive power output by the inverter when the real-time voltage is equal to the first voltage threshold, it further includes:

[0013] When the real-time voltage is less than or equal to the third voltage threshold, control the change rate of the positive reactive power output by the inverter to be maintained at the second preset reactive power change rate; the second preset reactive power change rate is greater than the first preset reactive power change rate.

[0014] In a possible implementation, controlling the change rate of the positive reactive power output by the inverter to be reduced to the first preset reactive power change rate includes:

[0015] Reduce the coefficient corresponding to the change rate of the positive reactive power output by the inverter to the first preset coefficient;

[0016] Wherein, the ratio of the first preset coefficient to the second preset coefficient is equal to the ratio of the first preset reactive power change rate to the second preset reactive power change rate; the second preset reactive power change rate is the change rate of the positive reactive power output by the inverter before reduction; the second preset coefficient is the coefficient corresponding to the second preset reactive power change rate.

[0017] In a possible implementation, before collecting the first negative reactive power output by the inverter when the real-time voltage is equal to the second voltage threshold, it further includes:

[0018] When the real-time voltage is greater than or equal to the second voltage threshold and less than the fourth voltage threshold, control the change rate of the negative reactive power output by the inverter to be reduced to the third preset reactive power change rate;

[0019] Wherein, when the change rate of the negative reactive power output by the inverter is the third preset reactive power change rate, the negative reactive power output by the inverter is collected once, and the decrement of the grid voltage is less than or equal to the second change threshold.

[0020] In a possible implementation, before collecting the first negative reactive power output by the inverter when the real-time voltage is equal to the second voltage threshold, it further includes:

[0021] When the real-time voltage is greater than or equal to the fourth voltage threshold, control the change rate of the negative reactive power output by the inverter to remain at the fourth preset reactive power change rate; the fourth preset reactive power change rate is greater than the third preset reactive power change rate.

[0022] In a possible implementation manner, controlling the change rate of the negative reactive power output by the inverter to decrease to the third preset reactive power change rate includes:

[0023] Reducing the coefficient corresponding to the change rate of the negative reactive power output by the inverter to the third preset coefficient;

[0024] Wherein, the ratio of the third preset coefficient to the fourth preset coefficient is equal to the ratio of the third preset reactive power change rate to the fourth preset reactive power change rate; the fourth preset reactive power change rate is the change rate of the negative reactive power output by the inverter before the reduction; the fourth preset coefficient is the coefficient corresponding to the fourth preset reactive power change rate.

[0025] In a second aspect, an embodiment of the present invention provides a control device for an inverter, including:

[0026] An acquisition module, configured to acquire the real-time voltage of the power grid;

[0027] An overvoltage control module, configured to collect the first positive reactive power output by the inverter when the real-time voltage is equal to the first voltage threshold, and control the positive reactive power output by the inverter to remain at the first positive reactive power; the first voltage threshold is determined according to a preset overvoltage protection voltage, and the first voltage threshold is less than or equal to the preset overvoltage protection voltage;

[0028] An undervoltage control module, configured to collect the first negative reactive power output by the inverter when the real-time voltage is equal to the second voltage threshold, and control the negative reactive power output by the inverter to remain at the first negative reactive power; the second voltage threshold is determined according to a preset undervoltage protection voltage, and the second voltage threshold is greater than or equal to the preset undervoltage protection voltage; the first voltage threshold is greater than the second voltage threshold.

[0029] In a third aspect, an embodiment of the present invention provides a control device, including a processor and a memory, the memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory to execute the control method of the inverter as described in the first aspect or any possible implementation manner of the first aspect above.

[0030] In a fourth aspect, an embodiment of the present invention provides an inverter, including the control device as described in the third aspect; the inverter is controlled by the control device.

[0031] In a fifth aspect, an embodiment of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the inverter control method described in the first aspect above or any possible implementation manner of the first aspect.

[0032] An embodiment of the present invention provides an inverter control method, device, control device, and inverter. When the real-time voltage of the power grid is equal to the first voltage threshold, it indicates that the power grid is about to trigger overvoltage protection. At this time, the first positive reactive power output by the inverter is collected, and the inverter is controlled to maintain the first positive reactive power output. Thus, the positive reactive power output by the inverter to the power grid will no longer increase the voltage of the power grid and will not trigger overvoltage protection. That is, before overvoltage protection, the voltage of the power grid can be controlled not to increase anymore. At the same time, the inverter can also maintain the maximum positive reactive power output without waste. Similarly, when the real-time voltage of the power grid is equal to the second voltage threshold, it indicates that the power grid is about to trigger undervoltage protection. At this time, the first negative reactive power output by the inverter is collected, and the inverter is controlled to maintain the first negative reactive power output. Thus, the negative reactive power output by the inverter to the power grid will no longer decrease the voltage of the power grid and will not trigger undervoltage protection. That is, before undervoltage protection, the voltage of the power grid can be controlled not to decrease anymore. At the same time, the inverter can also maintain the maximum negative reactive power output without waste. In addition, through this method, the power grid will not trigger overvoltage protection or undervoltage protection for a long time, thereby protecting the equipment in the power generation system and extending the service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0034] Figure 1 is a flowchart of the implementation of the inverter control method provided by an embodiment of the present invention;

[0035] Figure 2 is a schematic diagram of the inverter control device provided by an embodiment of the present invention;

[0036] Figure 3 is a schematic diagram of the control device provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] In the following description, specific details such as specific system architectures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present invention. However, those skilled in the art should understand that the present invention can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present invention.

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will be described through specific embodiments in conjunction with the accompanying drawings.

[0039] See Figure 1 , which shows an implementation flowchart of a control method for an inverter provided by an embodiment of the present invention. The execution subject of the control method for the inverter is a control device. This control device can be a controller, such as a DSP (Digital Signal Processor) and other controllers, or it can be other control devices, and specific limitations are not made here.

[0040] It should be noted that according to the control method for the inverter provided by the exemplary embodiments of the present application, it can be executed on the same device or on different devices. For example, assuming that the power generation system includes one inverter, the above control method for the inverter can be executed on the control device corresponding to the inverter; assuming that the power generation system includes at least two parallel inverters, the above control method for the inverter can be executed on the control device corresponding to each inverter, so that each inverter is controlled by its corresponding control device, or the above control method for the inverter can also be executed on one control device, so that each inverter is controlled by this control device; and so on.

[0041] See Figure 1 , and the above control method for the inverter is described in detail as follows:

[0042] In S101, obtain the real-time voltage of the power grid.

[0043] In the embodiments of the present application, the power generation system may include at least one inverter. The input end of the inverter may be connected to a photovoltaic module, and the output end of the inverter is connected to the power grid, or the output end of the inverter is connected to the power grid through a filtering device. Based on this connection relationship, the output of the inverter will affect the voltage of the power grid. Therefore, in the embodiments of the present application, the inverter is controlled through the real-time voltage of the power grid, so that the voltage of the power grid will not trigger overvoltage or undervoltage protection.

[0044] In the embodiments of the present application, there is no specific limitation on the method for obtaining the real-time voltage of the power grid, and any implementable method can be used. For example, it can be measured by a voltage sensor, or obtained by other means, and so on.

[0045] In S102, when the real-time voltage is equal to the first voltage threshold, the first positive reactive power output by the inverter is collected, and the positive reactive power output by the inverter is controlled to remain at the first positive reactive power; the first voltage threshold is determined according to the preset overvoltage protection voltage, and the first voltage threshold is less than or equal to the preset overvoltage protection voltage.

[0046] Among them, the preset overvoltage protection voltage may be the first-level overvoltage protection voltage in relevant standards. When the real-time voltage of the power grid is greater than the preset overvoltage protection voltage, overvoltage protection is triggered, which may cut off the connection relationship with the inverter, making the inverter unable to be put into use on the power grid again, and making the power grid unable to supply power to the load normally.

[0047] The first voltage threshold may be equal to the preset overvoltage protection voltage, or may be close to but slightly less than the preset overvoltage protection voltage, so that measures can be taken in time when overvoltage protection is not triggered, or when overvoltage protection is about to be triggered, so that the real-time voltage of the power grid will no longer continue to increase, overvoltage protection will not be triggered, the inverter can continue to be put into use, and the power grid can continue to supply power to the load normally.

[0048] In some possible implementation manners, the first voltage threshold may be obtained by subtracting the first preset voltage margin from the preset overvoltage protection voltage. The first preset voltage margin is greater than or equal to 0 and is a small value. For example, it may be 5V, 10V, or 15V, etc. Exemplarily, the preset overvoltage protection voltage may be 880V, the first preset voltage margin may be 10V, and correspondingly, the first voltage threshold may be 870V, etc.

[0049] In the embodiment of the present application, when the real-time voltage of the power grid is equal to the first voltage threshold, the positive reactive power output by the inverter is collected, and the positive reactive power output by the inverter collected at this time is used as the first positive reactive power.

[0050] If the positive reactive power output by the inverter continues to increase, then the real-time voltage of the power grid will continue to rise, which may trigger the overvoltage protection of the power grid. Therefore, in the embodiment of the present application, after the first positive reactive power is collected when the real-time voltage of the power grid is equal to the first voltage threshold, the positive reactive power output by the inverter is immediately controlled to remain at the first positive reactive power, so that the positive reactive power output by the inverter no longer increases, thereby no longer driving the real-time voltage of the power grid to increase, the real-time voltage of the power grid can be stabilized at the first voltage threshold or near the first voltage threshold, overvoltage protection will not be triggered, and at the same time, the maximum positive reactive power that the inverter can output at this time can be output, and there will be no waste.

[0051] When the real-time voltage of the power grid is equal to the first voltage threshold, there is no specific limitation on the negative reactive power output by the inverter, and it can be output according to the power grid dispatching requirements.

[0052] The embodiments of the present application do not specifically limit the specific implementation means for collecting the first positive reactive power output by the inverter, and any implementable means can be used. For example, it can be directly measured by a power meter or a power quality analyzer, etc.; it can also be obtained by calculating after measuring the voltage and current; and so on.

[0053] In some possible implementation manners, the power generation system may include at least one inverter; the input end of each inverter is connected to at least one photovoltaic module, and the output ends of the inverters are connected in parallel;

[0054] The above-mentioned step of collecting the first positive reactive power output by the inverter and controlling the positive reactive power output by the inverter to remain the first positive reactive power when the real-time voltage is equal to the first voltage threshold may include:

[0055] For each inverter, when the real-time voltage of the power grid is equal to the first voltage threshold, collect the first positive reactive power output by the inverter, and control the positive reactive power output by the inverter to remain the first positive reactive power output by the inverter.

[0056] In S103, when the real-time voltage is equal to the second voltage threshold, collect the first negative reactive power output by the inverter, and control the negative reactive power output by the inverter to remain the first negative reactive power; the second voltage threshold is determined according to the preset undervoltage protection voltage, and the second voltage threshold is greater than or equal to the preset undervoltage protection voltage; the first voltage threshold is greater than the second voltage threshold.

[0057] Among them, the preset undervoltage protection voltage may be the first-level undervoltage protection voltage in relevant standards. When the real-time voltage of the power grid is less than the preset undervoltage protection voltage, undervoltage protection is triggered, which may cut off the connection relationship between it and the inverter, making the inverter unable to be put into use in the power grid, and the power grid unable to supply power to the load normally.

[0058] The second voltage threshold may be equal to the preset undervoltage protection voltage, or may be close to but slightly greater than the preset undervoltage protection voltage, so that measures can be taken in time when undervoltage protection is not triggered, or when undervoltage protection is about to be triggered, to prevent the real-time voltage of the power grid from continuing to decrease, avoid triggering undervoltage protection, enable it to continue to supply power to the load normally, and enable the inverter to continue to be put into use.

[0059] In some possible implementation manners, the second voltage threshold may be obtained by adding a second preset voltage margin to the preset undervoltage protection voltage. The second preset voltage margin is greater than or equal to 0 and is a small value. For example, it can be 5V, 10V or 15V, etc. Exemplarily, the preset undervoltage protection voltage may be 720V, and the second preset voltage margin may be 10V. Correspondingly, the second voltage threshold may be 730V, and so on.

[0060] When the real-time voltage of the power grid in the embodiment of the present application is equal to the second voltage threshold, the negative reactive power output by the inverter is collected, and the negative reactive power output by the inverter collected at this time is used as the first negative reactive power.

[0061] If the negative reactive power output by the inverter continues to increase, the real-time voltage of the power grid will continue to drop, which may trigger undervoltage protection. Therefore, when the real-time voltage of the power grid is equal to the second voltage threshold in the embodiment of the present application, after the first negative reactive power is collected, the negative reactive power output by the inverter is immediately controlled to remain at the first negative reactive power, so that the negative reactive power output by the inverter no longer increases, and thus the real-time voltage of the power grid is no longer driven to decrease. This can make the real-time voltage of the power grid stable at the second voltage threshold or near the second voltage threshold, without triggering undervoltage protection. At the same time, it can also make the inverter output the maximum negative reactive power that can be output at this time, without wasting. Among them, the increase in the above negative reactive power can be understood as an increase in the absolute value of the negative reactive power. The above-mentioned making the inverter output the maximum negative reactive power that can be output at this time can be understood as making the inverter output the negative reactive power with the largest absolute value that can be output at this time.

[0062] When the real-time voltage of the power grid is equal to the second voltage threshold, there is no specific limitation on the positive reactive power output by the inverter, and it can be output according to the power grid dispatching requirements.

[0063] The embodiment of the present application does not specifically limit the specific implementation means for collecting the first negative reactive power output by the inverter, and any achievable means can be used. For example, it can be directly measured by a power meter or a power quality analyzer, etc.; it can also be obtained by calculating after measuring the voltage and current; and so on.

[0064] In some possible implementation manners, the power generation system may include at least one inverter; the input end of each inverter is connected to at least one photovoltaic module, and the output ends of each inverter are connected in parallel;

[0065] The above-mentioned collecting the first negative reactive power output by the inverter and controlling the negative reactive power output by the inverter to remain at the first negative reactive power when the real-time voltage is equal to the second voltage threshold may include:

[0066] For each inverter, when the real-time voltage of the power grid is equal to the second voltage threshold, the first negative reactive power output by the inverter is collected, and the negative reactive power output by the inverter is controlled to remain at the first negative reactive power output by the inverter.

[0067] In the embodiments of the present application, when the real-time voltage of the power grid is equal to the first voltage threshold, it indicates that the power grid is about to trigger overvoltage protection. At this time, the first positive reactive power output by the inverter is collected, and the inverter is controlled to maintain the output of the first positive reactive power. As a result, the positive reactive power output by the inverter to the power grid will no longer increase the voltage of the power grid and will not trigger overvoltage protection. That is, before overvoltage protection, the voltage of the power grid can be controlled not to increase anymore. At the same time, the inverter can also maintain the output of the maximum positive reactive power without causing waste. Similarly, when the real-time voltage of the power grid is equal to the second voltage threshold, it indicates that the power grid is about to trigger undervoltage protection. At this time, the first negative reactive power output by the inverter is collected, and the inverter is controlled to maintain the output of the first negative reactive power. As a result, the negative reactive power output by the inverter to the power grid will no longer decrease the voltage of the power grid and will not trigger undervoltage protection. That is, before undervoltage protection, the voltage of the power grid can be controlled not to decrease anymore. At the same time, the inverter can also maintain the output of the maximum negative reactive power without causing waste. In addition, through this method, the power grid will not trigger overvoltage protection or undervoltage protection, and will not trigger overvoltage protection or undervoltage protection for a long time. Therefore, the equipment in the power generation system can be protected, and the service life of the equipment can be extended.

[0068] In some embodiments, in S102, before collecting the first positive reactive power output by the inverter when the real-time voltage is equal to the first voltage threshold, it may further include:

[0069] When the real-time voltage is less than or equal to the first voltage threshold and greater than the third voltage threshold, control the change rate of the positive reactive power output by the inverter to be reduced to the first preset reactive power change rate;

[0070] Wherein, when the change rate of the positive reactive power output by the inverter is the first preset reactive power change rate, the first positive reactive power output by the inverter is collected once, and the voltage increment of the power grid is less than or equal to the first change threshold.

[0071] In the embodiments of the present application, the above change rate of the positive reactive power output by the inverter represents the speed at which the positive reactive power output by the inverter changes with time. If it is large, it means that the positive reactive power output by the inverter changes rapidly with time; if it is small, it means that the positive reactive power output by the inverter changes slowly with time.

[0072] When the real-time voltage of the power grid is equal to the first voltage threshold, it also takes time to collect the first positive reactive power output by the inverter. During the process of collecting the first positive reactive power, if the change rate of the positive reactive power output by the above inverter is large, then during the time of collecting the first positive reactive power, the change amount of the positive reactive power output by the inverter is also large, that is, the positive reactive power output by the inverter increases rapidly, and the rapid increase of the positive reactive power will also drive the rapid increase of the real-time voltage of the power grid, and the over-voltage protection of the power grid may be triggered before the first positive reactive power is collected. In addition, if the positive reactive power output by the inverter changes rapidly, it may not be possible to capture the first positive reactive power in time.

[0073] Therefore, in the embodiment of the present application, when the real-time voltage of the power grid has not reached the first voltage threshold and is rapidly increasing to the first voltage threshold, that is, when the real-time voltage of the power grid is less than or equal to the first voltage threshold and the real-time voltage of the power grid is greater than the third voltage threshold, the change rate of the positive reactive power output by the inverter is controlled to decrease and is reduced to the first preset reactive power change rate, so that the change speed of the positive reactive power output by the inverter is slower. During the process of collecting the first positive reactive power, the voltage of the power grid will not increase too much, and further, when the real-time voltage of the power grid is equal to the first voltage threshold, the first positive reactive power output by the inverter can be collected before the over-voltage protection is triggered.

[0074] Among them, the third voltage threshold is less than the first voltage threshold, and the third voltage threshold can also be greater than the second voltage threshold. The third voltage threshold can be obtained by subtracting the third preset voltage margin from the first voltage threshold. The third preset voltage margin is greater than 0, and its value can be set according to actual needs. For example, it can be 20V, 30V or 40V, etc. Exemplarily, the first voltage threshold can be 870V, the third preset voltage margin can be 30V, and correspondingly, the third voltage threshold can be 840V.

[0075] When the change rate of the positive reactive power output by the inverter is the first preset reactive power change rate, the increment of the voltage of the power grid when collecting the positive reactive power output by the inverter once can be understood as the difference obtained by subtracting the voltage of the power grid at the start of collecting the positive reactive power output by the inverter once from the voltage of the power grid at the end of collecting the positive reactive power output by the inverter once when the change rate of the positive reactive power output by the inverter is the first preset reactive power change rate.

[0076] Exemplarily, assuming that the duration of collecting the positive reactive power output by the inverter once is 10ms, then when the change rate of the positive reactive power output by the inverter is the first preset reactive power change rate, the increment of the voltage of the power grid when collecting the positive reactive power output by the inverter once is the voltage of the power grid at the end of the 10ms minus the voltage of the power grid at the start of the 10ms.

[0077] The first change threshold can be set according to actual requirements. Exemplarily, in order not to trigger overvoltage protection, the first change threshold can be less than or equal to the first preset voltage margin.

[0078] It should be noted that during the process of collecting the first positive reactive power output by the inverter as described above, even when the real-time voltage of the power grid is greater than the first voltage threshold, the change rate of the positive reactive power output by the inverter still needs to be maintained at the first preset reactive power change rate.

[0079] In some possible implementation manners, as described above, the power generation system may include at least one inverter;

[0080] The above-mentioned controlling the change rate of the positive reactive power output by the inverter to be reduced to the first preset reactive power change rate when the real-time voltage is less than or equal to the first voltage threshold and greater than the third voltage threshold may include:

[0081] For each inverter, when the real-time voltage of the power grid is less than or equal to the first voltage threshold and greater than the third voltage threshold, control the change rate of the positive reactive power output by the inverter to be reduced to the first preset reactive power change rate.

[0082] In some embodiments, in S102, before collecting the first positive reactive power output by the inverter when the real-time voltage is equal to the first voltage threshold, it may further include:

[0083] When the real-time voltage is less than or equal to the third voltage threshold, control the change rate of the positive reactive power output by the inverter to be maintained at the second preset reactive power change rate; the second preset reactive power change rate is greater than the first preset reactive power change rate.

[0084] In the embodiments of the present application, when the real-time voltage of the power grid is less than or equal to the third voltage threshold, it indicates that the voltage of the power grid is far from the preset overvoltage protection voltage. At this time, even if the rate of the positive reactive power output by the inverter is relatively fast, overvoltage protection will not be triggered. Therefore, the change rate of the positive reactive power output by the inverter can be controlled to be maintained at the relatively large second preset reactive power change rate, so that the inverter can meet the output demand of the positive reactive power in a timely and rapid manner.

[0085] Among them, the second preset reactive power change rate may be the maximum change rate of the positive reactive power output by the inverter. The first preset reactive power change rate may be less than the second preset reactive power change rate. For example, the first preset reactive power change rate may be 1 / 10 or 1 / 5 of the second preset reactive power change rate, etc. The first preset reactive power change rate can be determined based on the limitations in the foregoing embodiments.

[0086] In some possible implementation manners, as described above, the power generation system may include at least one inverter;

[0087] When the real-time voltage is less than or equal to the third voltage threshold, controlling the change rate of the positive reactive power output by the inverter to remain at the second preset reactive power change rate may include:

[0088] For each inverter, when the real-time voltage of the power grid is less than or equal to the third voltage threshold, controlling the change rate of the positive reactive power output by the inverter to remain at the second preset reactive power change rate.

[0089] In some embodiments, controlling the change rate of the positive reactive power output by the inverter to decrease to the first preset reactive power change rate includes:

[0090] Reducing the coefficient corresponding to the change rate of the positive reactive power output by the inverter to the first preset coefficient;

[0091] Wherein, the ratio of the first preset coefficient to the second preset coefficient is equal to the ratio of the first preset reactive power change rate to the second preset reactive power change rate; the second preset reactive power change rate is the change rate of the positive reactive power output by the inverter before the reduction; the second preset coefficient is the coefficient corresponding to the second preset reactive power change rate.

[0092] In the embodiments of the present application, the change rate of the positive reactive power output by the inverter can be adjusted by adjusting the coefficient corresponding to the change rate of the positive reactive power output by the inverter. Exemplarily, multiplying the maximum change rate of the positive reactive power output by the inverter by the current coefficient corresponding to the change rate of the positive reactive power output by the inverter can obtain the current change rate of the positive reactive power output by the inverter. Wherein, the range of the coefficient corresponding to the change rate of the positive reactive power output by the inverter is [0,1].

[0093] The above-mentioned second preset coefficient is the coefficient corresponding to the second preset reactive power change rate, that is, the coefficient corresponding to the change rate of the positive reactive power output by the inverter before the reduction.

[0094] First preset coefficient / Second preset coefficient = First preset reactive power change rate / Second preset reactive power change rate.

[0095] The first preset reactive power change rate is obtained by multiplying the maximum change rate of the positive reactive power output by the inverter by the first preset coefficient; the second preset reactive power change rate is obtained by multiplying the maximum change rate of the positive reactive power output by the inverter by the second preset coefficient.

[0096] The ratio of the first preset coefficient to the second preset coefficient can be set according to actual needs. Exemplarily, the first preset coefficient can be 0.1, the second preset coefficient can be 1, and so on.

[0097] Correspondingly, the above-mentioned controlling the change rate of the positive reactive power output by the inverter to remain at the second preset reactive power change rate includes:

[0098] The coefficient corresponding to the rate of change of the positive reactive power output by the inverter is maintained at a second preset coefficient.

[0099] In some possible implementation manners, controlling the rate of change of the positive reactive power output by the inverter to be reduced to a first preset reactive power change rate may include:

[0100] The coefficient corresponding to the rate of change of the positive reactive power output by the inverter is reduced to a first preset coefficient.

[0101] Controlling the rate of change of the positive reactive power output by the inverter to be maintained at a second preset reactive power change rate may include:

[0102] The coefficient corresponding to the rate of change of the positive reactive power output by the inverter is maintained at a second preset coefficient.

[0103] In some embodiments, in S103, before collecting the first negative reactive power output by the inverter when the real-time voltage is equal to the second voltage threshold, it further includes:

[0104] When the real-time voltage is greater than or equal to the second voltage threshold and less than the fourth voltage threshold, controlling the rate of change of the negative reactive power output by the inverter to be reduced to a third preset reactive power change rate;

[0105] Wherein, when the rate of change of the negative reactive power output by the inverter is the third preset reactive power change rate, the negative reactive power output by the inverter is collected once, and the voltage reduction of the power grid is less than or equal to a second change threshold.

[0106] In the embodiments of the present application, the rate of change of the negative reactive power output by the inverter represents the degree of change of the negative reactive power output by the inverter with time. If it is large, it means that the negative reactive power output by the inverter changes rapidly with time; if it is small, it means that the negative reactive power output by the inverter changes slowly with time.

[0107] When the real-time voltage of the power grid is equal to the second voltage threshold, it also takes time to collect the first negative reactive power output by the inverter. During the process of collecting the first negative reactive power, if the rate of change of the negative reactive power output by the inverter is large, then during the period of collecting the first negative reactive power, the change amount of the negative reactive power output by the inverter is also large, that is, the negative reactive power output by the inverter increases rapidly, and the rapid increase of the negative reactive power will also drive the rapid decrease of the real-time voltage of the power grid, and the undervoltage protection may be triggered before the first negative reactive power is collected. In addition, if the change of the negative reactive power output by the inverter is fast, it may not be possible to capture the first negative reactive power in time.

[0108] Therefore, when the real-time voltage of the power grid has not yet dropped to the second voltage threshold and is about to drop to the second voltage threshold, that is, when the real-time voltage of the power grid is greater than or equal to the second voltage threshold and less than the fourth voltage threshold, the embodiment of the present application controls the change rate of the inverter's output negative reactive power to decrease and be reduced to the third preset reactive power change rate, so that the change speed of the inverter's output negative reactive power is slower. During the process of collecting the first negative reactive power, the voltage of the power grid will not drop too much. Furthermore, when the real-time voltage of the power grid is equal to the second voltage threshold, the first negative reactive power output by the inverter can be collected before triggering the undervoltage protection.

[0109] Among them, the fourth voltage threshold is greater than the second voltage threshold, and the fourth voltage threshold can also be less than the first voltage threshold, and the fourth voltage threshold can also be less than the third voltage threshold. The fourth voltage threshold can be obtained by adding a fourth preset voltage margin to the second voltage threshold. The fourth preset voltage margin is greater than 0, and its value can be set according to actual needs. For example, it can be 20V, 30V or 40V, etc. Exemplarily, the second voltage threshold can be 730V, the fourth preset voltage margin can be 30V, and correspondingly, the fourth voltage threshold can be 760V.

[0110] When the change rate of the inverter's output negative reactive power is the third preset reactive power change rate, the reduction in the voltage of the power grid when collecting the negative reactive power output by the inverter once can be understood as the difference obtained by subtracting the voltage of the power grid at the end of collecting the negative reactive power output by the inverter once from the voltage of the power grid at the start of collecting the negative reactive power output by the inverter once when the change rate of the inverter's output negative reactive power is the third preset reactive power change rate.

[0111] Exemplarily, assuming that the duration of collecting the negative reactive power output by the inverter once is 10ms, then when the change rate of the inverter's output negative reactive power is the third preset reactive power change rate, the reduction in the voltage of the power grid when collecting the negative reactive power output by the inverter once is the voltage of the power grid at the start of the 10ms minus the voltage of the power grid at the end of the 10ms.

[0112] The second change threshold can be set according to actual needs. Exemplarily, in order not to trigger the undervoltage protection, the second change threshold can be less than or equal to the second preset voltage margin.

[0113] It should be noted that during the process of collecting the first negative reactive power output by the inverter, even when the real-time voltage of the power grid is less than the second voltage threshold, the change rate of the inverter's output positive reactive power still needs to remain at the third preset reactive power change rate.

[0114] In some possible implementation manners, as described above, the power generation system may include at least one inverter;

[0115] When the real-time voltage is greater than or equal to the second voltage threshold and less than the fourth voltage threshold, controlling the change rate of the negative reactive power output by the inverter to be reduced to a third preset reactive power change rate may include:

[0116] For each inverter, when the real-time voltage of the power grid is greater than or equal to the second voltage threshold and less than the fourth voltage threshold, controlling the change rate of the negative reactive power output by the inverter to be reduced to a third preset reactive power change rate.

[0117] In some embodiments, in S103, before collecting the first negative reactive power output by the inverter when the real-time voltage is equal to the second voltage threshold, it further includes:

[0118] When the real-time voltage is greater than or equal to the fourth voltage threshold, controlling the change rate of the negative reactive power output by the inverter to be maintained at a fourth preset reactive power change rate; the fourth preset reactive power change rate is greater than the third preset reactive power change rate.

[0119] In the embodiments of the present application, when the real-time voltage of the power grid is greater than or equal to the fourth voltage threshold, it indicates that the voltage of the power grid is far from the preset undervoltage protection voltage. At this time, even if the rate of the negative reactive power output by the inverter is fast, the undervoltage protection will not be triggered. Therefore, the change rate of the negative reactive power output by the inverter can be controlled to be maintained at a larger fourth preset reactive power change rate, so that the inverter can meet the output demand of the negative reactive power in a timely and rapid manner.

[0120] Wherein, the fourth preset reactive power change rate may be the maximum change rate of the negative reactive power output by the inverter. The third preset reactive power change rate may be less than the fourth preset reactive power change rate. For example, the third preset reactive power change rate may be 1 / 10 or 1 / 5 of the fourth preset reactive power change rate, etc. The third preset reactive power change rate may be determined based on the limitations in the foregoing embodiments.

[0121] In some possible implementation manners, the third preset reactive power change rate may be equal to the first preset reactive power change rate, and the fourth preset reactive power change rate may be equal to the second preset reactive power change rate.

[0122] In some possible implementation manners, as described above, the inverter of the power generation system may include at least one inverter;

[0123] When the real-time voltage is greater than or equal to the fourth voltage threshold, controlling the change rate of the negative reactive power output by the inverter to be maintained at a fourth preset reactive power change rate may include:

[0124] For each inverter, when the real-time voltage of the power grid is greater than or equal to the fourth voltage threshold, controlling the change rate of the negative reactive power output by the inverter to be maintained at a fourth preset reactive power change rate.

[0125] In some embodiments, controlling the change rate of the inverter output negative reactive power to be reduced to a third preset reactive power change rate includes:

[0126] Reducing the coefficient corresponding to the change rate of the inverter output negative reactive power to a third preset coefficient;

[0127] Wherein, the ratio of the third preset coefficient to the fourth preset coefficient is equal to the ratio of the third preset reactive power change rate to the fourth preset reactive power change rate; the fourth preset reactive power change rate is the change rate of the inverter output negative reactive power before the reduction; the fourth preset coefficient is the coefficient corresponding to the fourth preset reactive power change rate.

[0128] In the embodiments of the present application, the change rate of the inverter output negative reactive power can be adjusted by adjusting the coefficient corresponding to the change rate of the inverter output negative reactive power. Exemplarily, multiplying the maximum change rate of the inverter output negative reactive power by the current coefficient corresponding to the change rate of the inverter output negative reactive power can obtain the current change rate of the inverter output negative reactive power. Wherein, the range of the coefficient corresponding to the change rate of the inverter output negative reactive power is [0,1].

[0129] The above-mentioned fourth preset coefficient is the coefficient corresponding to the fourth preset reactive power change rate, that is, the coefficient corresponding to the change rate of the inverter output negative reactive power before the reduction.

[0130] Third preset coefficient / Fourth preset coefficient = Third preset reactive power change rate / Fourth preset reactive power change rate.

[0131] The third preset reactive power change rate is obtained by multiplying the maximum change rate of the inverter output negative reactive power by the third preset coefficient; the fourth preset reactive power change rate is obtained by multiplying the maximum change rate of the inverter output negative reactive power by the fourth preset coefficient.

[0132] The ratio of the third preset coefficient to the fourth preset coefficient can be set according to actual needs. Exemplarily, the third preset coefficient can be 0.1, the fourth preset coefficient can be 1, and so on.

[0133] Correspondingly, the above-mentioned controlling the change rate of the inverter output negative reactive power to be maintained at the fourth preset reactive power change rate includes:

[0134] Controlling the coefficient corresponding to the change rate of the inverter output negative reactive power to be maintained at the fourth preset coefficient.

[0135] In some possible implementation manners, the above-mentioned controlling the change rate of the inverter output negative reactive power to be reduced to the third preset reactive power change rate may include:

[0136] The coefficient corresponding to controlling the change rate of the negative reactive power output by the inverter is reduced to a third preset coefficient.

[0137] The above-mentioned controlling the change rate of the negative reactive power output by the inverter to remain at a fourth preset reactive power change rate may include:

[0138] The coefficient corresponding to controlling the change rate of the negative reactive power output by the inverter is maintained at a fourth preset coefficient.

[0139] It should be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution. The order of execution of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

[0140] Figure 2 The structural schematic diagram of the control device of the inverter provided by the embodiment of the present invention is shown. For the convenience of description, only the parts related to the embodiment of the present invention are shown and are described in detail as follows:

[0141] As Figure 2 shown, the control device 30 of the inverter includes: an acquisition module 31, an overvoltage control module 32, and an undervoltage control module 33.

[0142] The acquisition module 31 is used to acquire the real-time voltage of the power grid;

[0143] The overvoltage control module 32 is used to collect the first positive reactive power output by the inverter when the real-time voltage is equal to the first voltage threshold, and control the positive reactive power output by the inverter to remain at the first positive reactive power; the first voltage threshold is determined according to the preset overvoltage protection voltage, and the first voltage threshold is less than or equal to the preset overvoltage protection voltage;

[0144] The undervoltage control module 33 is used to collect the first negative reactive power output by the inverter when the real-time voltage is equal to the second voltage threshold, and control the negative reactive power output by the inverter to remain at the first negative reactive power; the second voltage threshold is determined according to the preset undervoltage protection voltage, and the second voltage threshold is greater than or equal to the preset undervoltage protection voltage; the first voltage threshold is greater than the second voltage threshold.

[0145] In a possible implementation manner, the overvoltage control module 32 may further be used for:

[0146] Before collecting the first positive reactive power output by the inverter when the real-time voltage is equal to the first voltage threshold, when the real-time voltage is less than or equal to the first voltage threshold and greater than the third voltage threshold, controlling the change rate of the positive reactive power output by the inverter to be reduced to a first preset reactive power change rate;

[0147] Wherein, when the change rate of the positive reactive power output by the inverter is the first preset reactive power change rate, the positive reactive power output by the inverter is collected once, and the increment of the grid voltage is less than or equal to the first change threshold.

[0148] In a possible implementation, the overvoltage control module 32 can also be used for:

[0149] Before collecting the first positive reactive power output by the inverter when the real-time voltage is equal to the first voltage threshold, when the real-time voltage is less than or equal to the third voltage threshold, control the change rate of the positive reactive power output by the inverter to remain at the second preset reactive power change rate; the second preset reactive power change rate is greater than the first preset reactive power change rate.

[0150] In a possible implementation, in the overvoltage control module 32, controlling the change rate of the positive reactive power output by the inverter to decrease to the first preset reactive power change rate includes:

[0151] Reducing the coefficient corresponding to the change rate of the positive reactive power output by the inverter to the first preset coefficient;

[0152] Wherein, the ratio of the first preset coefficient to the second preset coefficient is equal to the ratio of the first preset reactive power change rate to the second preset reactive power change rate; the second preset reactive power change rate is the change rate of the positive reactive power output by the inverter before the reduction; the second preset coefficient is the coefficient corresponding to the second preset reactive power change rate.

[0153] In a possible implementation, the undervoltage control module 33 can also be used for:

[0154] Before collecting the first negative reactive power output by the inverter when the real-time voltage is equal to the second voltage threshold, when the real-time voltage is greater than or equal to the second voltage threshold and less than the fourth voltage threshold, control the change rate of the negative reactive power output by the inverter to decrease to the third preset reactive power change rate;

[0155] Wherein, when the change rate of the negative reactive power output by the inverter is the third preset reactive power change rate, the negative reactive power output by the inverter is collected once, and the decrement of the grid voltage is less than or equal to the second change threshold.

[0156] In a possible implementation, the undervoltage control module 33 can also be used for:

[0157] Before collecting the first negative reactive power output by the inverter when the real-time voltage is equal to the second voltage threshold, when the real-time voltage is greater than or equal to the fourth voltage threshold, control the change rate of the negative reactive power output by the inverter to remain at the fourth preset reactive power change rate; the fourth preset reactive power change rate is greater than the third preset reactive power change rate.

[0158] In a possible implementation, in the undervoltage control module 33, controlling the change rate of the negative reactive power output by the inverter to be reduced to a third preset reactive power change rate includes:

[0159] Reducing the coefficient corresponding to the change rate of the negative reactive power output by the inverter to a third preset coefficient;

[0160] Wherein, the ratio of the third preset coefficient to the fourth preset coefficient is equal to the ratio of the third preset reactive power change rate to the fourth preset reactive power change rate; the fourth preset reactive power change rate is the change rate of the negative reactive power output by the inverter before the reduction; the fourth preset coefficient is the coefficient corresponding to the fourth preset reactive power change rate.

[0161] Figure 3 is a schematic diagram of the control device provided by an embodiment of the present invention. As Figure 3 shown, the control device 4 of this embodiment includes: a processor 40 and a memory 41. The memory 41 is used to store a computer program 42, and the processor 40 is used to call and run the computer program 42 stored in the memory 41 to execute the steps in the above-mentioned embodiments of the control method for each inverter, such as Figure 1 S101 to S103 shown. Alternatively, the processor 40 is used to call and run the computer program 42 stored in the memory 41 to implement the functions of each module / unit in the above-mentioned device embodiments, such as Figure 2 the functions of each module shown.

[0162] Exemplarily, the computer program 42 can be divided into one or more modules / units. The one or more modules / units are stored in the memory 41 and executed by the processor 40 to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing specific functions, and these instruction segments are used to describe the execution process of the computer program 42 in the control device 4. For example, the computer program 42 can be divided into Figure 2 each module shown.

[0163] The control device 4 may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art can understand that Figure 3 merely an example of the control device 4, which does not constitute a limitation on the control device 4. It may include more or fewer components than shown in the figure, or combine some components, or different components. For example, the control device may further include input / output devices, network access devices, buses, etc.

[0164] The processor 40 may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0165] The memory 41 may be an internal storage unit of the control device 4, such as the hard disk or memory of the control device 4. The memory 41 may also be an external storage device of the control device 4, such as a plug-in hard disk equipped on the control device 4, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. Further, the memory 41 may also include both the internal storage unit and the external storage device of the control device 4. The memory 41 is used to store the computer program and other programs and data required by the control device 4. The memory 41 may also be used to temporarily store the data that has been output or will be output.

[0166] Corresponding to the above control device, an embodiment of the present invention further provides an inverter, including the above control device; the inverter is controlled by the control device.

[0167] An embodiment of the present application further provides a power generation system, including at least one inverter as described above.

[0168] For the relevant descriptions of the inverter and the power generation system, reference may be made to the descriptions in the foregoing embodiments, and details are not repeated here.

[0169] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above-mentioned division of each functional unit and module is used as an example. In actual applications, the above functions can be allocated to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of this application. The specific working processes of the units and modules in the above system can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0170] In the above embodiments, the descriptions of the respective embodiments have their own emphases. For parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0171] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or by a combination of computer software and electronic hardware. Whether these functions are executed in the form of hardware or software depends on the specific application and design constraints of the technical solution. Professionals can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0172] In the embodiments provided by the present invention, it should be understood that the disclosed device / control device and method can be implemented in other ways. For example, the device / control device embodiments described above are only illustrative. For example, the division of the module or unit is only a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection to each other can be through some interfaces. The indirect coupling or communication connection of the device or unit can be in an electrical, mechanical or other form.

[0173] The unit described as a separate component may or may not be physically separated. The component displayed as a unit may or may not be a physical unit, that is, it can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0174] In addition, in each embodiment of the present invention, each functional unit may be integrated into a processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of a software functional unit.

[0175] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it may be stored in a computer-readable storage medium. Based on such an understanding, to implement all or part of the processes in the above-mentioned embodiment methods of the present invention, it may also be completed by a computer program instructing relevant hardware. The computer program may be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above-mentioned control method embodiments of each inverter can be implemented. Among them, the computer program includes computer program code, and the computer program code may be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer-readable medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0176] The above-mentioned embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A control method for an inverter, characterized in that: include: Get the real-time voltage of the power grid; When the real-time voltage is equal to a first voltage threshold, collecting a first positive reactive power output by the inverter, and controlling the positive reactive power output by the inverter to remain at the first positive reactive power; The first voltage threshold is determined according to a preset overvoltage protection voltage, and the first voltage threshold is less than or equal to the preset overvoltage protection voltage; When the real-time voltage is equal to a second voltage threshold, collecting a first negative reactive power output by the inverter, and controlling the negative reactive power output by the inverter to remain at the first negative reactive power; The second voltage threshold is determined according to a preset undervoltage protection voltage, and the second voltage threshold is greater than or equal to the preset undervoltage protection voltage; The first voltage threshold is greater than the second voltage threshold.

2. The inverter control method according to claim 1, characterized in that: Before collecting the first positive reactive power output by the inverter when the real-time voltage is equal to the first voltage threshold, the method further includes: When the real-time voltage is less than or equal to the first voltage threshold and greater than a third voltage threshold, controlling the inverter to output a positive reactive power whose change rate is reduced to a first preset reactive power change rate; Among them, when the change rate of the positive reactive power output by the inverter is the first preset reactive change rate, the positive reactive power output by the inverter is collected once, and the increment of the voltage of the power grid is less than or equal to the first change threshold.

3. The control method of the inverter according to claim 2, characterized in that: Before collecting the first positive reactive power output by the inverter when the real-time voltage is equal to the first voltage threshold, the method further includes: When the real-time voltage is less than or equal to the third voltage threshold, the change rate of the positive reactive power output by the inverter is controlled to be maintained at a second preset reactive change rate; the second preset reactive change rate is greater than the first preset reactive change rate.

4. The control method of the inverter according to claim 2, characterized in that: The step of controlling the inverter to reduce the rate of change of the positive reactive power output to a first preset reactive power change rate comprises: Reducing the coefficient corresponding to the rate of change of the positive reactive power output by the inverter to a first preset coefficient; Among them, the ratio of the first preset coefficient to the second preset coefficient is equal to the ratio of the first preset reactive change rate to the second preset reactive change rate; the second preset reactive change rate is the change rate of the positive reactive power output by the inverter before it is reduced; the second preset coefficient is the coefficient corresponding to the second preset reactive change rate.

5. The inverter control method according to any one of claims 1 to 4, characterized in that: Before collecting the first negative reactive power output by the inverter when the real-time voltage is equal to the second voltage threshold, the method further includes: When the real-time voltage is greater than or equal to the second voltage threshold and less than a fourth voltage threshold, controlling the inverter to output a change rate of negative reactive power to be reduced to a third preset reactive power change rate; Among them, when the change rate of the negative reactive power output by the inverter is the third preset reactive change rate, the negative reactive power output by the inverter is collected once, and the reduction in the voltage of the power grid is less than or equal to the second change threshold.

6. The control method of the inverter according to claim 5, characterized in that: Before collecting the first negative reactive power output by the inverter when the real-time voltage is equal to the second voltage threshold, the method further includes: When the real-time voltage is greater than or equal to the fourth voltage threshold, the change rate of the negative reactive power output by the inverter is controlled to be maintained at a fourth preset reactive change rate; the fourth preset reactive change rate is greater than the third preset reactive change rate.

7. The control method of the inverter according to claim 5, characterized in that: The step of controlling the inverter to output negative reactive power at a rate of change lowered to a third preset reactive power rate of change includes: Reducing the coefficient corresponding to the rate of change of the negative reactive power output by the inverter to a third preset coefficient; Among them, the ratio of the third preset coefficient to the fourth preset coefficient is equal to the ratio of the third preset reactive change rate to the fourth preset reactive change rate; the fourth preset reactive change rate is the change rate of the negative reactive power output by the inverter before it is reduced; the fourth preset coefficient is the coefficient corresponding to the fourth preset reactive change rate.

8. A control device for an inverter, characterized in that: include: An acquisition module is used to obtain the real-time voltage of the power grid; an overvoltage control module, configured to collect a first positive reactive power output by the inverter when the real-time voltage is equal to a first voltage threshold, and control the positive reactive power output by the inverter to remain at the first positive reactive power; The first voltage threshold is determined according to a preset overvoltage protection voltage, and the first voltage threshold is less than or equal to the preset overvoltage protection voltage; an undervoltage control module, configured to collect a first negative reactive power output by the inverter when the real-time voltage is equal to a second voltage threshold, and control the negative reactive power output by the inverter to remain at the first negative reactive power; The second voltage threshold is determined according to a preset undervoltage protection voltage, and the second voltage threshold is greater than or equal to the preset undervoltage protection voltage; The first voltage threshold is greater than the second voltage threshold.

9. A control device, characterized in that: The invention comprises a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory to execute the inverter control method according to any one of claims 1 to 7.

10. An inverter, characterized in that: Comprising the control device as claimed in claim 9; the inverter is controlled by the control device.

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