Method and apparatus for frequency adjustment

Abstract

Embodiments of the present application provide a method and apparatus for frequency adjustment, which can reduce the duration of grid connection and improve the accuracy of grid connection operation. The method for frequency adjustment includes: obtaining a first phase, where the first phase is the phase of a first voltage output by a power generation device to be grid-connected; determining a target duration when the first phase and a second phase are not synchronized, where the target duration is the duration required to adjust a first frequency to a target value and then restore it to the first frequency, the first frequency is the frequency of the first voltage, and the second phase is the phase of the grid voltage; and adjusting the first frequency based on the target duration so that the phase of the first voltage is synchronized with the second phase.

Description

Technical Field

[0001] This application relates to the field of power technologies, and particularly to a method and device for frequency adjustment. Background Art

[0002] In a power system, the generator quasi-synchronous paralleling operation is a key technology. When there is a phase difference during the paralleling process between a generator set and the power grid, it is necessary to adjust the phase of the grid-connected generator to reduce the phase difference. However, the characteristics of different types of generators are different, and these characteristics are affected by various factors such as generator capacity and prime mover characteristics, resulting in difficulty for traditional fixed-parameter control methods to adapt to the phase adjustment requirements of different generators. Summary of the Invention

[0003] Embodiments of this application provide a method and device for frequency adjustment, which can reduce the duration of grid connection and improve the accuracy of grid connection operation.

[0004] In a first aspect, a method for frequency adjustment is provided. The method includes: obtaining a first phase, where the first phase is the phase of a first voltage output by a power generation device to be grid-connected; in a case where the first phase and a second phase are not synchronized, determining a target duration, where the target duration is the duration required to adjust a first frequency to a target value and then restore it to the first frequency, the first frequency being the frequency of the first voltage, and the second phase being the phase of the grid voltage; and adjusting the first frequency based on the target duration so that the phase of the first voltage is synchronized with the second phase.

[0005] Since the frequency modulation characteristics of different power generation devices are different, during the phase adjustment process, the durations required to adjust the frequency of the voltages output by different power generation devices to the target values may be different. In the embodiments of this application, during the phase adjustment process, first, the duration required to adjust the first frequency of the first voltage output by the power generation device to be grid-connected to the target value and then restore it to the first frequency is determined, and then the first frequency is adjusted according to this duration, that is, the frequency modulation time of the power generation device to be grid-connected is determined according to the frequency modulation characteristics of the power generation device to be grid-connected, and this frequency modulation time is used as the time parameter for phase adjustment control. Thus, not only can the duration of grid connection be reduced, but also the accuracy of grid connection operation can be improved, thereby improving the grid connection efficiency. In addition, there is a certain relationship between frequency and phase. Therefore, by adjusting the frequency to adjust the phase, the operation is simple and easy to implement.

[0006] In some possible implementation manners, the target duration is the duration required to reduce the initial frequency of the first voltage by the target value and then restore it to the first frequency.

[0007] This technical solution achieves the synchronization between the phase of the first voltage and the second phase by reducing the frequency of the first voltage. Thus, the safety of frequency adjustment and phase synchronization can be improved.

[0008] In some possible implementation manners, the target duration is the duration required to adjust the initial frequency of the first voltage to the target value and then restore it to the first frequency within one cycle. Based on the target duration, adjusting the frequency of the first voltage includes: adjusting the frequency of the first voltage within multiple cycles based on the target duration.

[0009] This technical solution sets the target duration as the duration for adjusting the frequency within one cycle, and adjusts the frequency of the first voltage within multiple cycles based on the target duration. Thus, the adjustment value of the frequency of the first voltage within each cycle, that is, the target value, can be relatively small, reducing the possibility that the phase of the first voltage cannot be synchronized with the second phase due to setting the target value too large, and further improving the grid connection efficiency.

[0010] In some possible implementation manners, the method further includes: detecting the phase of the first voltage during the process of adjusting the first frequency based on the target duration; and determining that the process of adjusting the first frequency ends when it is detected that the phase of the first voltage is synchronized with the second phase.

[0011] This technical solution detects the phase of the first voltage during the process of adjusting the frequency of the first voltage. Thus, after the phase of the first voltage is synchronized with the second phase, the adjustment of the frequency can be stopped in a timely manner, and then the power generation device to be grid-connected can be connected to the grid in a shorter time, not only reducing the possibility of still adjusting the first frequency after the phase of the first voltage is synchronized with the second phase, but also reducing the duration of grid connection and improving the grid connection efficiency.

[0012] In some possible implementation manners, determining the target duration includes: collecting the initial frequency of the first voltage; and determining the target duration according to the first frequency and the second frequency, where the second frequency is the frequency of the grid voltage; and before determining the target duration, the first frequency and the second frequency are in a synchronized state.

[0013] This technical solution, since the target duration is related to the frequency, determines the target duration according to the collected first frequency and second frequency, so that the accuracy of the obtained target duration is relatively high.

[0014] In some possible implementation manners, collecting the initial frequency of the first voltage includes: collecting the first frequency multiple times within a preset time period; determining the target duration according to the first frequency and the second frequency includes: comparing multiple first frequencies with the second frequency to obtain a comparison result; and determining the target duration according to the comparison result.

[0015] In this technical solution, the target duration is determined by multiple first frequencies collected multiple times, that is, the target duration is determined according to more first frequencies, which can further improve the accuracy of the target duration.

[0016] In some possible implementation manners, determining the target duration according to the comparison result includes: determining a first moment when a first absolute value is greater than a first preset value, and adjusting the first frequency, where the first absolute value is the maximum value among the absolute values of the differences between multiple first frequencies and the second frequency; determining a second moment when a second absolute value is less than a second preset value, where the second absolute value is the maximum value among the absolute values of the differences between the adjusted multiple first frequencies and the second frequency; and determining the difference between the first moment and the second moment as the target duration.

[0017] In some possible implementation manners, before obtaining the first phase, the method further includes: obtaining the initial frequency and the first amplitude of the first voltage; in a case where the initial frequency is not synchronized with the second frequency, adjusting the initial frequency to the first frequency, where the first frequency is in a synchronized state with the second frequency, and the second frequency is the frequency of the grid voltage; and / or in a case where the first amplitude is not synchronized with the second amplitude, adjusting the first amplitude to make the first amplitude synchronized with the second amplitude, where the second amplitude is the amplitude of the grid voltage.

[0018] In this technical solution, in addition to the phase, the amplitude and frequency of the first voltage are also obtained, and in a case where the amplitude is not synchronized with the amplitude of the grid voltage, and / or, in a case where the frequency is not synchronized with the frequency of the grid voltage, the amplitude and frequency of the first voltage are adjusted to make them all synchronized with the amplitude and frequency of the grid voltage. In this way, the purpose of connecting the power generation device to be paralleled to the grid can be achieved, so that the power generation device to be paralleled can better serve the power system.

[0019] Second aspect, a device for frequency adjustment is provided, including: a processing unit configured to obtain a first phase, where the first phase is the phase of a first voltage output by a device to be grid-connected for power generation; the processing unit is further configured to determine a target duration in case the first phase and a second phase are not synchronized, where the target duration is the duration required to adjust the first frequency to a target value and then restore it to the first frequency, the first frequency being the frequency of the first voltage and the second phase being the phase of the grid voltage; an adjustment unit configured to adjust the first frequency based on the target duration so that the phase of the first voltage is synchronized with the second phase.

[0020] Third aspect, a device for frequency adjustment is provided, including a processor and a memory, where the memory is configured to store a computer program, and the processor is configured to call the computer program to execute the method in the first aspect or its various implementation manners described above. Description of the Drawings

[0021] Figure 1 A schematic diagram showing the quasi-synchronous paralleling of a power generation device according to an embodiment of the present application is shown.

[0022] Figure 2 A schematic flowchart showing a method for frequency adjustment according to an embodiment of the present application is shown.

[0023] Figure 3 A schematic diagram showing a target duration according to an embodiment of the present application is shown.

[0024] Figure 4 Shows Figure 3 The corresponding time diagram.

[0025] Figure 5 A schematic flowchart showing the determination of a target duration according to an embodiment of the present application is shown.

[0026] Figure 6 A schematic diagram showing the grid-connection process of a device to be grid-connected for power generation according to an embodiment of the present application is shown.

[0027] Figure 7 A schematic block diagram showing a device for frequency adjustment according to an embodiment of the present application is shown.

[0028] Figure 8 A schematic block diagram showing another device for frequency adjustment according to an embodiment of the present application is shown. Detailed Embodiments

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly describe the technical solutions in the embodiments of this application in conjunction with the accompanying drawings in the embodiments of this application. Apparently, the described embodiments are part of the embodiments of this application, rather than all of them. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

[0030] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used in the description of this application are only for the purpose of describing specific embodiments, and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the description and claims of this application or the above drawings are used to distinguish different objects, rather than to describe a specific order or primary-secondary relationship.

[0031] The orientation terms appearing in the following description are all the directions shown in the drawings, and do not limit the specific structure of this application. In the description of this application, it should also be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] Referring to "embodiments" in this application means that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appearing in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described in this application can be combined with other embodiments.

[0033] The term "a plurality of" as used in this application means two or more (including two). Similarly, "a plurality of groups" means two or more groups (including two groups), and "a plurality of pieces" means two or more pieces (including two pieces).

[0034] Precise synchronization paralleling is an important technology in the power system, mainly used to parallel operate generator sets or different parts of the power system to achieve stable power supply and load distribution in the power system. Among them, precise synchronization paralleling means that in the paralleling operation, it is allowed that there are certain differences in voltage, frequency and phase between the generator set to be paralleled and the operating system, but still smooth paralleling can be achieved. Compared with traditional synchronization paralleling, precise synchronization paralleling relaxes the strict requirements for voltage, frequency and phase synchronization conditions, thereby reducing the operation difficulty, reducing the impact current during paralleling, and improving the safety and reliability of the system.

[0035] When there is a phase difference during the paralleling process between the generator set and the power grid, it is necessary to adjust the frequency of the grid-connected generator to change the rotational speed, thereby reducing the phase difference. However, the characteristics of different types of generators are different, and these characteristics are affected by various factors such as the generator capacity and the characteristics of the prime mover, resulting in that the traditional fixed-parameter control method is difficult to adapt to the phase adjustment requirements of different generators. For example, the traditional fixed-parameter control method requires a long phase adjustment process.

[0036] In view of this, the embodiments of the present application provide a frequency adjustment method. When the first phase and the second phase are not synchronized, the target duration is determined, and the frequency of the first voltage is adjusted based on the target duration so that the phase of the first voltage is synchronized with the second phase. Among them, the first phase is the phase of the first voltage output by the power generation device to be grid-connected, the second phase is the phase of the grid voltage, the target duration is the duration required to adjust the first frequency to the target value and then restore it to the first frequency, and the first frequency is the frequency of the first voltage. Since the frequency modulation characteristics of different power generation devices are different, during the phase adjustment process, the durations required to adjust the frequencies of the voltages output by different power generation devices to the target values may be different. In the embodiments of the present application, during the phase adjustment process, first the duration required to adjust the first frequency of the first voltage output by the power generation device to be grid-connected to the target value and then restore it to the first frequency is determined, and then the frequency of the first voltage output by the power generation device to be grid-connected is adjusted according to this duration, that is, the frequency modulation time of the power generation device to be grid-connected is determined according to the frequency modulation characteristics of the power generation device to be grid-connected, and this frequency modulation time is used as the time parameter for phase adjustment control, so that not only the grid connection duration can be reduced, but also the accuracy of the grid connection operation can be improved, and further the grid connection efficiency can be improved. In addition, there is a certain relationship between frequency and phase. Therefore, by adjusting the frequency to adjust the phase, the operation is simple and easy to implement.

[0037] The embodiments of the present application can be applied to the process of precise synchronization paralleling operation. Figure 1 Shows a schematic diagram of a possible precise synchronization paralleling of a power generation device. As Figure 1As shown, the generator set includes power generation devices SG1 and SG2. SG2 starts first to form a three-phase power grid. Before grid connection, SG1 needs to adjust the amplitude, frequency, and phase of the output voltage. Specifically, the controller can collect the voltage parameters output by SG2, namely amplitude 2, frequency 2, and phase 2, and collect the voltage parameters output by SG1, namely amplitude 1, frequency 1, and phase 1, and compare the voltage parameters of SG1 and SG2. If the difference between the voltage parameters of SG1 and the voltage parameters of SG2 is within a certain range, that is, the difference between amplitude 1 and amplitude 2 is within a certain range, the difference between frequency 1 and frequency 2 is within a certain range, and the difference between phase 1 and phase 2 is within a certain range, then closing and grid connection are allowed. If at least one of the voltage parameters of SG1 and the voltage parameters of SG2 has a difference not within this range, such as the difference between amplitude 1 and amplitude 2 is not within this range, then the voltage parameters of SG1 or SG2 are adjusted until the difference between the voltage parameters of SG1 and the voltage parameters of SG2 is within this range, and then closing and grid connection are allowed.

[0038] Figure 2 FIG. shows a schematic flowchart of a frequency adjustment method 200 according to an embodiment of the present application. Exemplarily, the method 200 can be applied in the process of quasi-synchronous paralleling. The method 200 can include at least some of the following content.

[0039] S210: Obtain a first phase, where the first phase is the phase of the first voltage output by the power generation device to be grid-connected.

[0040] S220: In the case where the first phase and the second phase are not synchronized, determine a target duration, where the target duration is the duration required to adjust the first frequency to a target value and then restore it to the first frequency. The first frequency is the frequency of the first voltage, and the second phase is the phase of the grid voltage.

[0041] S230: Based on the target duration, adjust the first frequency so that the phase of the first voltage is synchronized with the second phase.

[0042] Since the frequency modulation characteristics of different power generation devices are different, therefore, during the phase modulation process, the durations required to adjust the first frequency of the voltages output by different power generation devices to the target values may be different. In the embodiment of the present application, during the phase modulation process, first determine the duration required to adjust the first frequency of the first voltage output by the power generation device to be grid-connected to the target value and then restore it to the first frequency, and then adjust the frequency of the first voltage output by the power generation device to be grid-connected according to this duration, that is, determine the frequency modulation time of the power generation device to be grid-connected according to the frequency modulation characteristics of the power generation device to be grid-connected, and use this frequency modulation time as the time parameter for phase modulation control. Thus, not only can the duration used for grid connection be reduced, but also the accuracy of grid connection operation can be improved, thereby improving the grid connection efficiency. In addition, there is a certain relationship between frequency and phase. Therefore, adjusting the phase by adjusting the frequency is simple in operation and easy to implement.

[0043] Among them, the power generation device to be connected to the grid can be a power generation device ready to be connected to the grid, such as Figure 1 SG1 in

[0044] The non-synchronization of the first phase and the second phase can be understood as: the absolute value of the difference between the first phase and the second phase is greater than the phase threshold. The synchronization of the first phase and the second phase can be understood as: the absolute value of the difference between the first phase and the second phase is less than or equal to the phase threshold. For example, the phase threshold can be 10°, 8°, 5°, 3°, etc.

[0045] The target value can be set in advance. For example, in order to improve the accuracy of grid connection, the target value can be set relatively small. For example, the target value can be set in advance to 2 Hz (hertz), 1 Hz, 0.5 Hz, 0.3 Hz, etc.

[0046] The target value can be a fixed value, that is, the target value is the same value under any environment and any power generation device to be connected to the grid. Or, the target value can also be a variable value. For example, the target value can be different according to the characteristics of the power generation device to be connected to the grid, the first frequency of the power generation device to be connected to the grid, the environment where the power generation device to be connected to the grid is located, etc.

[0047] In the embodiment of the present application, the target duration is the duration required to adjust the first frequency to the target value and then restore it to the first frequency. In this way, during the process of adjusting the phase of the first voltage, the frequency of the first voltage can be kept synchronized with the frequency of the grid voltage, reducing the possibility that the phase of the first voltage is synchronized with the phase of the grid voltage but the frequency of the first voltage is not synchronized with the frequency of the grid voltage.

[0048] As Figure 3 shown, Figure 3 in

[0049] Figure 4 For Figure 3 corresponding time. It can be seen that the start time of adjusting the first frequency is 8.4 s, and the time when the first frequency returns to 50 Hz is 10.15 s, then the target duration is 1.5 s. Among them, Figure 4 the ordinate is the number of counted points.

[0050] Optionally, a frequency modulation instruction can be received, and the frequency modulation instruction is used to indicate adjusting the first frequency. After receiving the frequency modulation instruction, the first frequency can be adjusted based on the target duration.

[0051] Further, method 200 may further include: during the process of adjusting the frequency of the first voltage based on the target duration, detecting the phase of the first voltage, and ending the process of adjusting the first frequency when it is detected that the phase of the first voltage is synchronized with the second phase.

[0052] In this technical solution, during the process of adjusting the frequency of the first voltage, the phase of the first voltage is detected. Thus, after the phase of the first voltage is synchronized with the second phase, the adjustment of the frequency can be stopped in a timely manner, and then the device to be grid-connected for power generation can be connected to the grid in a relatively short time. This not only reduces the possibility of still adjusting the frequency of the first voltage after the phase of the first voltage is synchronized with the second phase, but also reduces the duration of grid connection and improves the grid connection efficiency.

[0053] Optionally, the phase of the first voltage can be detected in real time.

[0054] Optionally, the phase of the first voltage can be detected periodically. For example, the phase of the first voltage can be detected once every 5 ms, 10 ms, 1 s, 5 s, 10 s, etc.

[0055] In some embodiments, the target duration may be the duration required to reduce the first frequency by a target value and then restore it to the first frequency.

[0056] In this technical solution, the purpose of synchronizing the phase between the first voltage and the second phase is achieved by reducing the frequency of the first voltage. Thus, the safety of frequency adjustment and phase synchronization can be improved.

[0057] Generally, during the process of synchronizing the phase of the first voltage with the second phase, it may be necessary to adjust the frequency multiple times to achieve the purpose of synchronizing the phase between the first voltage and the second phase. Therefore, in some embodiments, the target duration may be the duration required to adjust the initial frequency of the first voltage by a target value within one cycle. At this time, S230 may specifically include: adjusting the frequency of the first voltage within multiple cycles based on the target duration.

[0058] In this technical solution, the target duration is set as the duration of adjusting the frequency within one cycle, and the first frequency is adjusted within multiple cycles based on the target duration. Thus, the adjustment value of the first frequency within each cycle, that is, the target value, can be relatively small, reducing the possibility that the target value is set too large and the phase of the first voltage cannot be synchronized with the second phase, and thereby improving the grid connection efficiency.

[0059] For example, if the target value is large, the first phase is 60°, and the second phase is 40°, during the process of adjusting the first frequency, the phase of the first voltage gradually approaches the second phase. When the phase of the first voltage is about to be adjusted to 40°, due to the large target value, the phase of the first voltage may be adjusted to 35° or other values less than 40°, thus failing to achieve synchronization with the second phase.

[0060] There may be a certain time interval between two adjacent cycles, or the next cycle starts immediately after the end of the previous cycle.

[0061] As an example, the change value of the phase of the first voltage in each cycle can be determined according to the adjustment value of the frequency and the target duration in each cycle. Then, according to the difference between the phase of the first voltage and the second phase, and according to the change value of the phase of the first voltage in each cycle, the number of multiple cycles can be determined. After that, the frequency of the first voltage can be adjusted within the cycles of this number.

[0062] For example, according to the adjustment value of the frequency and the target duration in each cycle, it is determined that the change value of the phase of the first voltage in each cycle is 2°, and the difference between the phase of the first voltage and the second phase is 26°. Then, the number of multiple cycles can be determined to be 13, so that the frequency of the first voltage can be adjusted within 13 cycles.

[0063] As another example, as described above, during the process of adjusting the frequency of the first voltage within multiple cycles, the phase of the first voltage can be monitored in real time. If the phase of the first voltage reaches synchronization with the second phase, the adjustment of the frequency can be stopped.

[0064] In each of the multiple cycles, the duration for which the frequency of the first voltage is adjusted is the target duration.

[0065] Furthermore, in each of the multiple cycles, the target value is the same. For example, in each cycle, the initial frequency of the first voltage is reduced by 0.5 Hz.

[0066] It should be noted that in the last cycle of the multiple cycles, during the process of adjusting the frequency of the first voltage, the phase of the first voltage may have reached synchronization with the second phase. Therefore, in the last cycle of the multiple cycles, the duration for which the frequency of the first voltage is adjusted may be less than that of other cycles.

[0067] It should also be noted that after the phase of the first voltage reaches synchronization with the second phase, the frequency of the first voltage needs to be restored to the first frequency.

[0068] In some embodiments, S230 may specifically include: determining the target duration according to the attribute parameters of the device to be interconnected and generating electricity.

[0069] Alternatively, the target duration of the power generation device to be grid-connected can be determined according to the historical grid-connection data of the power generation device to be grid-connected.

[0070] Alternatively, S220 may specifically include: collecting a first frequency, and determining the target duration according to the first frequency and a second frequency. Wherein, the second frequency is the frequency of the grid voltage, and before determining the target duration, the first frequency and the second frequency are in a synchronous state.

[0071] In this technical solution, since the target duration is related to the frequency, therefore, determining the target duration according to the collected first frequency and second frequency makes the accuracy of the obtained target duration relatively high.

[0072] Optionally, the first frequency can be collected at any time, or the first frequency can be collected at a fixed time.

[0073] As an example, the first frequency can be collected only once.

[0074] At this time, the first frequency can be compared with the second frequency. If the absolute value of the difference between the first frequency and the second frequency is greater than a first preset value, the moment when the absolute value is greater than the first preset value can be determined as the first moment, and the first frequency is adjusted. During the adjustment process, the first frequency is collected, and the moment when the absolute value of the difference between the first frequency and the second frequency is less than or equal to a second preset value is determined as the second moment. The difference between the first moment and the second moment is the target duration.

[0075] In the embodiment of the present application, before adjusting the phase of the first voltage, if the initial frequency of the first voltage is not synchronized with the frequency of the grid voltage (i.e., the second frequency), the initial frequency of the first voltage can be adjusted. After adjusting the initial frequency of the first voltage to the first frequency, if the first frequency is synchronized with the second frequency, the adjustment of the frequency of the first voltage is stopped. At this time, it can be considered that the magnitude of the first frequency is the same as the magnitude of the second frequency. During the process of determining the target duration, the first frequency needs to be adjusted to a target value. For example, when the first frequency is decreased by the target value, at this time, the first frequency changes, and the magnitude of the first frequency is different from the magnitude of the second frequency. If the absolute value of the difference between the first frequency and the second frequency is greater than the first preset value, it can be considered that the adjustment of the first frequency starts, and this moment is the start moment of the target duration. Since the first frequency will eventually return to the first frequency after being adjusted by the target value, at this time, it can be considered that the first frequency is the same as the second frequency. Therefore, if the absolute value of the difference between the adjusted first frequency and the second frequency is less than the second preset value, it indicates that the first frequency has returned to the original value, and this moment is the end moment of the target duration.

[0076] As another example, the first frequency can be collected multiple times within a preset time period, and then the multiple first frequencies and the second frequency are compared to obtain a comparison result, and the target duration is determined according to the comparison result.

[0077] In this technical solution, the target duration is determined by multiple first frequencies collected multiple times, that is, the target duration is determined according to more first frequencies, which can further improve the accuracy of the target duration.

[0078] In the embodiments of the present application, neither the preset time period nor the number of the first frequencies collected is specifically limited. For example, the first frequency can be collected 50 times within the preset time period, or the first frequency can be collected 20 times, etc.

[0079] Optionally, the first frequency can be randomly collected within the preset time period, or the first frequency can be periodically collected within the preset time period.

[0080] Optionally, the moment when the first absolute value is greater than the first preset value can be determined as the first moment, and the first frequency is adjusted. The moment when the second absolute value is less than the second preset value is determined as the second moment, and the difference between the first moment and the second moment is determined as the target duration.

[0081] Wherein, the first absolute value is the maximum value among the absolute values of the differences between the multiple first frequencies and the second frequency, and the second absolute value is the maximum value among the absolute values of the differences between the adjusted multiple first frequencies and the second frequency.

[0082] Determining the moment when the first absolute value is greater than the first preset value as the first moment can be understood as: as long as one absolute value is greater than the first preset value, that is, as long as one first frequency exceeds the preset range, this moment can be determined as the start moment of the target duration.

[0083] Optionally, the first preset value and the second preset value can be the same or different. When the first preset value and the second preset value are the same, for example, the first preset value and the second preset value can be 0.1 Hz, 0.2 Hz, 0.05 Hz, etc.

[0084] Or, the first absolute value can be the minimum value among the absolute values of the differences between the multiple first frequencies and the second frequency. At this time, determining the moment when the first absolute value is greater than the first preset value as the first moment can be understood as: all absolute values need to be greater than the first preset value, that is, all first frequencies exceed the preset range, then this moment is the start moment of the target duration.

[0085] Figure 5 Shows a possible implementation manner of determining the target duration. In Figure 5 Among them, the first frequency is collected n times, f represents the first frequency, f nThe first frequency representing the nth acquisition, δ represents the first preset value and the second preset value, 50 represents the second frequency, with the unit of Hz.

[0086] In 510, a frequency modulation instruction is received.

[0087] In 520, the first frequency is acquired multiple times.

[0088] In 530, it is determined whether the maximum value among the absolute values of the differences between multiple first frequencies and the second frequency is greater than δ.

[0089] If it is greater than δ, 540 is executed; if it is not greater than δ, 520 is executed.

[0090] In 540, the moment greater than δ is determined as the first moment and the first frequency is adjusted.

[0091] In 550, during the process of adjusting the first frequency, the adjusted first frequency is acquired multiple times, and it is determined whether the maximum value among the absolute values of the differences between the adjusted first frequency and the second frequency is less than or equal to δ.

[0092] If it is less than or equal to δ, 560 is executed; if it is greater than δ, 520 is executed.

[0093] In 560, the moment less than or equal to δ is determined as the second moment.

[0094] At this time, the process of determining the target duration ends, where the difference between the second moment and the first moment is the target duration.

[0095] Figure 6 Illustrates the grid - connection process of a grid - connection power generation device according to an embodiment of the present application. It should be understood that Figure 6 Only one phase voltage of the first voltage is shown. From Figure 6 it can be seen that during the grid - connection process, the difference between the phase of the first voltage and the second phase becomes smaller and smaller until the phase of the first voltage is the same as the second phase.

[0096] In addition to the phase, during the process of quasi - synchronous paralleling, method 200 may further include: obtaining the initial frequency and the first amplitude of the first voltage, and in the case where the initial frequency is not synchronized with the second frequency, adjusting the initial frequency to the first frequency, where the first frequency and the second frequency are in a synchronous state, and / or, in the case where the first amplitude is not synchronized with the second amplitude, adjusting the first amplitude so that the first amplitude and the second amplitude reach synchronization. Wherein, the second amplitude is the amplitude of the grid voltage.

[0097] In this technical solution, in addition to the phase, the amplitude and frequency of the first voltage are also obtained, and when the amplitude is not synchronized with the amplitude of the grid voltage and / or when the frequency is not synchronized with the frequency of the grid voltage, the amplitude and frequency of the first voltage are adjusted so that they are both synchronized with the amplitude and frequency of the grid voltage. In this way, the purpose of connecting the power generation device to be paralleled to the grid can be achieved, so that the power generation device to be paralleled can better serve the power system.

[0098] Similar to the phase, the initial frequency being not synchronized with the second frequency can be understood as: the absolute value of the difference between the initial frequency and the second frequency is greater than the frequency threshold, and the first frequency being synchronized with the second frequency can be understood as: the absolute value of the difference between the first frequency and the second frequency is less than or equal to the frequency threshold.

[0099] The first amplitude being not synchronized with the second amplitude can be understood as: the absolute value of the difference between the first amplitude and the second amplitude is greater than the amplitude threshold, and the first amplitude being synchronized with the second amplitude can be understood as: the absolute value of the difference between the first amplitude and the second amplitude is less than or equal to the amplitude threshold.

[0100] It should be understood that the implementation manners of adjusting the initial frequency and the first amplitude can refer to the existing manners of adjusting the frequency and amplitude. For the sake of simplicity, this application will not describe them in detail.

[0101] In the embodiments of this application, the magnitudes of the sequence numbers of the above processes 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 this application.

[0102] Moreover, on the premise of no conflict, the various embodiments described in this application and / or the technical features in the various embodiments can be combined arbitrarily, and the technical solutions obtained after combination should also fall within the protection scope of this application.

[0103] The method for frequency adjustment in the embodiments of this application is described in detail above. Next, the device for frequency adjustment in the embodiments of this application will be described. It should be understood that the method for frequency adjustment in the embodiments of this application can be applied to the device for frequency adjustment in the embodiments of this application.

[0104] Figure 7 The schematic block diagram of the device 700 for frequency adjustment in the embodiments of this application is shown. As Figure 7 shown, the device 700 for frequency adjustment can include:

[0105] A processing unit 710, configured to obtain a first phase, where the first phase is the phase of a first voltage output by a power generation device to be connected to the grid.

[0106] The processing unit 710 is further configured to determine a target duration when the first phase and the second phase are not synchronized. The target duration is the duration required to adjust the first frequency to a target value and then restore it to the first frequency. The first frequency is the frequency of the first voltage, and the second phase is the phase of the grid voltage.

[0107] An adjustment unit 720 is configured to adjust the first frequency based on the target duration, so that the phase of the first voltage is synchronized with the second phase.

[0108] Optionally, in an embodiment of the present application, the target duration is the duration required to reduce the first frequency by the target value and then restore it to the first frequency.

[0109] Optionally, in an embodiment of the present application, the target duration is the duration required to adjust the first frequency by the target value and then restore it to the first frequency within one period. The adjustment unit 720 is specifically configured to: adjust the first frequency within multiple periods based on the target duration.

[0110] Optionally, in an embodiment of the present application, the frequency adjustment device 700 further includes: a detection unit configured to detect the phase of the first voltage during the process of adjusting the first frequency based on the target duration; the adjustment unit 720 is further configured to: end the process of adjusting the frequency of the first voltage when it is detected that the phase of the first voltage is synchronized with the second phase.

[0111] Optionally, in an embodiment of the present application, the processing unit 710 is specifically configured to: collect the first frequency; determine the target duration according to the first frequency and the second frequency. The second frequency is the frequency of the grid voltage. Before determining the target duration, the first frequency and the second frequency are in a synchronized state.

[0112] Optionally, in an embodiment of the present application, the processing unit 710 is specifically configured to: collect the first frequency multiple times within a preset time period; compare the multiple first frequencies with the second frequency to obtain a comparison result; determine the target duration according to the comparison result.

[0113] Optionally, in an embodiment of the present application, the processing unit 710 is specifically configured to: determine a first moment when a first absolute value is greater than a first preset value, and adjust the first frequency. The first absolute value is the maximum value among the absolute values of the differences between the multiple first frequencies and the second frequency; determine a second moment when a second absolute value is less than a second preset value. The second absolute value is the maximum value among the absolute values of the differences between the adjusted multiple first frequencies and the second frequency; determine the difference between the first moment and the second moment as the target duration.

[0114] Optionally, in the embodiments of the present application, the processing unit 710 is further configured to: before obtaining the first phase, obtain the initial frequency and the first amplitude of the first voltage; in the case where the initial frequency is not synchronized with the second frequency, adjust the initial frequency to the first frequency, where the first frequency is in a synchronized state with the second frequency, and the second frequency is the frequency of the grid voltage; and / or in the case where the first amplitude is not synchronized with the second amplitude, adjust the first amplitude so that the first amplitude is synchronized with the second amplitude, where the second amplitude is the amplitude of the grid voltage.

[0115] It should be understood that the frequency adjustment device 700 can implement the corresponding operations in the method 200. For the sake of brevity, it will not be described in detail here.

[0116] Figure 8 FIG. 9 is a schematic hardware structure diagram of a frequency adjustment device 800 according to an embodiment of the present application. The frequency adjustment device 800 includes a memory 801, a processor 802, a communication interface 803, and a bus 804. Among them, the memory 801, the processor 802, and the communication interface 803 are communicatively connected to each other through the bus 804.

[0117] The memory 801 may be a read-only memory (ROM), a static storage device, and a random access memory (RAM). The memory 801 may store a program. When the program stored in the memory 801 is executed by the processor 802, the processor 802 and the communication interface 803 are configured to execute each step of the frequency adjustment method according to the embodiments of the present application.

[0118] The processor 802 may be a general-purpose central processing unit (CPU), a microprocessor, an application specific integrated circuit (ASIC), a graphics processing unit (GPU), or one or more integrated circuits, and is configured to execute relevant programs to implement the functions required by the units in the device according to the embodiments of the present application, or execute the frequency adjustment method according to the embodiments of the present application.

[0119] The processor 802 may also be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the frequency adjustment method according to the embodiments of the present application may be completed by the integrated logic circuit in the hardware of the processor 802 or by instructions in software form.

[0120] The above-mentioned processor 802 may also be a general-purpose processor, a digital signal processor (DSP), an ASIC, a field programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present application may be directly embodied as being executed by a hardware processor, or executed by a combination of hardware and software modules in the processor. The software module may be located in a mature storage medium in the art such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, registers, etc. This storage medium is located in the memory 801, and the processor 802 reads the information in the memory 801 and combines its hardware to complete the functions required to be executed by the units included in the frequency adjustment device 800 of the embodiments of the present application, or executes the frequency adjustment method of the embodiments of the present application.

[0121] The communication interface 803 uses a transceiver device such as, but not limited to, a transceiver to implement communication between the frequency adjustment device 800 and other devices or communication networks.

[0122] The bus 804 may include a path for transmitting information between the various components of the frequency adjustment device 800 (for example, the memory 801, the processor 802, the communication interface 803).

[0123] It should be noted that although the above-mentioned frequency adjustment device 800 only shows a memory, a processor, and a communication interface, in the specific implementation process, those skilled in the art should understand that the frequency adjustment device 800 may also include other devices necessary for normal operation. At the same time, according to specific needs, those skilled in the art should understand that the frequency adjustment device 800 may also include hardware devices for implementing other additional functions. In addition, those skilled in the art should understand that the frequency adjustment device 800 may also only include the devices necessary for implementing the embodiments of the present application, and does not necessarily include Figure 8 all the devices shown in

[0124] The embodiments of the present application also provide a computer-readable storage medium for storing a computer program, and the computer program is used to execute the methods of the various embodiments of the present application described above.

[0125] The above-mentioned computer-readable storage medium may be a transient computer-readable storage medium or a non-transient computer-readable storage medium.

[0126] An embodiment of the present application also provides a computer program product. The computer program product includes a computer program stored on a computer-readable storage medium. The computer program includes program instructions that, when executed by a computer, cause the computer to execute the above frequency adjustment method.

[0127] Although the present application has been described with reference to the preferred embodiments, various improvements can be made to it and components therein can be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims

Claims

1. A method for frequency adjustment, characterized in that, The method includes: Obtaining a first phase, where the first phase is the phase of a first voltage output by a power generation device to be grid-connected; When the first phase and a second phase are not synchronized, determining a target duration, where the target duration is the duration required to adjust a first frequency to a target value and then restore it to the first frequency, the first frequency being the frequency of the first voltage, and the second phase being the phase of the grid voltage; Based on the target duration, adjusting the first frequency so that the phase of the first voltage synchronizes with the second phase.

2. The method according to claim 1, wherein The target duration is the duration required to decrease the first frequency by the target value and then restore it to the first frequency.

3. The method according to claim 1, wherein The target duration is the duration required to adjust the first frequency by the target value and then restore it to the first frequency within one cycle. Based on the target duration, adjusting the first frequency includes: Based on the target duration, adjusting the first frequency in multiple cycles.

4. The method according to any one of claims 1 to 3, characterized in that The method further includes: During the process of adjusting the first frequency based on the target duration, detecting the phase of the first voltage; When it is detected that the phase of the first voltage synchronizes with the second phase, determining that the process of adjusting the first frequency ends.

5. The method according to any one of claims 1 to 3, characterized in that Determining the target duration includes: Collecting the first frequency; Based on the first frequency and a second frequency, determining the target duration, the second frequency being the frequency of the grid voltage; Wherein, before determining the target duration, the first frequency and the second frequency are in a synchronized state.

6. The method according to claim 5, characterized in that, Collecting the first frequency includes: Within a preset time period, collecting the first frequency multiple times; Based on the first frequency and the second frequency, determining the target duration includes: Comparing multiple first frequencies with the second frequency to obtain a comparison result; Based on the comparison result, determining the target duration.

7. The method according to claim 6, characterized in that, Based on the comparison result, determining the target duration includes: Determining a first moment when a first absolute value is greater than a first preset value, and adjusting the first frequency. The first absolute value is the maximum value among the absolute values of the differences between multiple first frequencies and the second frequency; Determining a second moment when a second absolute value is less than a second preset value. The second absolute value is the maximum value among the absolute values of the differences between the adjusted multiple first frequencies and the second frequency; Determining the difference between the first moment and the second moment as the target duration.

8. The method according to any one of claims 1 to 3, characterized in that Before obtaining the first phase, the method further includes: Obtaining an initial frequency and a first amplitude of the first voltage; When the initial frequency is not synchronized with the second frequency, adjusting the initial frequency to the first frequency, where the first frequency and the second frequency are in a synchronized state, and the second frequency is the frequency of the grid voltage; and / or When the first amplitude is not synchronized with a second amplitude, adjusting the first amplitude so that the first amplitude synchronizes with the second amplitude, the second amplitude being the amplitude of the grid voltage.

9. A device for frequency adjustment, characterized in that, Includes: A processing unit for obtaining a first phase, where the first phase is the phase of a first voltage output by a power generation device to be connected to the grid; The processing unit is further configured to determine a target duration when the first phase and a second phase are not synchronized, where the target duration is the duration required to adjust a first frequency to a target value and then restore it to the first frequency, the first frequency being the frequency of the first voltage, and the second phase being the phase of the grid voltage; An adjustment unit for adjusting the first frequency based on the target duration so that the phase of the first voltage is synchronized with the second phase.

10. A device for frequency adjustment, characterized in that, Comprising: A memory for storing programs; A processor for executing the programs stored in the memory, and when the programs stored in the memory are executed, the processor is configured to execute the frequency adjustment method according to any one of claims 1 to 7.

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