Phase-locking device, method and phase-locking control system

Abstract

The present invention discloses a phase-locking device, method and phase-locking control system. The phase-locking device includes a hysteresis module, which is used to determine the first zero-crossing point and the second zero-crossing point of the power grid signal, and output a square wave signal corresponding to the power grid signal according to the first zero-crossing point and the second zero-crossing point; a capture module, which is used to determine the first frequency and the first phase corresponding to the power grid signal according to the square wave signal; a phase-locking module, which is used to output the second frequency and the second phase corresponding to the power grid signal according to the power grid signal; and a fault-tolerant module, which is used to determine that the first frequency is the power grid frequency of the power grid signal and the first phase is the power grid phase of the power grid signal when the difference between the first frequency and the preset frequency is within the preset difference range, and when the difference exceeds the preset difference range, the second frequency is determined to be the power grid frequency and the second phase is the power grid phase. The technical solution of the present invention achieves the effect of reducing the phase-locking error and improving the accuracy of the phase-locking.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a phase-locking device, method and phase-locking control system. Background Art

[0002] In recent years, with the increasing energy crisis and environmental problems, solar energy has developed rapidly as a clean and renewable energy source.

[0003] Photovoltaic power generation systems are often used to meet the power supply needs of remote areas. However, the power grids at the end of the power grids in remote areas and islands are usually designed with relatively small loads, showing weak power grid characteristics. Voltage distortion in weak power grids can easily cause the output deviation or even failure of the photovoltaic inverter phase-locked loop, so the power grid synchronization method under weak power grids is crucial.

[0004] At present, power grid synchronization generally adopts the hardware zero-crossing detection phase-locking method. The hardware zero-crossing detection phase-locking method is sensitive to external signal interference, and the hysteresis loop is more prone to jitter. A stronger filtering link is often used to filter the signal, causing delays, which can easily cause the phase-locked value to deviate from the actual value, resulting in a large phase-locking error. Summary of the invention

[0005] The present invention provides a phase locking device, method and phase locking control system to reduce phase locking error and improve phase locking accuracy.

[0006] According to one aspect of the present invention, a phase locking device is provided, the phase locking device comprising:

[0007] A hysteresis module, wherein the first end of the hysteresis module is used to input a power grid signal, the second end of the hysteresis module is used to input a first threshold voltage, the third end of the hysteresis module is used to input a power grid signal, and the fourth end of the hysteresis module is used to input a second threshold voltage, the hysteresis module is used to determine a first zero-crossing point of the power grid signal according to the power grid signal and the first threshold voltage, determine a second zero-crossing point of the power grid signal according to the power grid signal and the second threshold voltage, and output a square wave signal corresponding to the power grid signal according to the first zero-crossing point and the second zero-crossing point;

[0008] A capture module, wherein a first end of the capture module is connected to a fifth end of the hysteresis module, and the capture module is used to determine a first frequency and a first phase corresponding to the power grid signal according to the square wave signal;

[0009] A phase-locking module, wherein a first end of the phase-locking module is used to input the grid signal, and the phase-locking module is used to output a second frequency and a second phase corresponding to the grid signal according to the grid signal;

[0010] A fault-tolerant module, wherein the first end of the fault-tolerant module is connected to the second end of the capture module, and the second end of the fault-tolerant module is connected to the second end of the phase-locked module. The fault-tolerant module is used to determine that the first frequency is the grid frequency of the grid signal and the first phase is the grid phase of the grid signal when the difference between the first frequency and the preset frequency is within a preset difference range, and when the difference exceeds the preset difference range, determine that the second frequency is the grid frequency and the second phase is the grid phase.

[0011] Optionally, the hysteresis module includes a first comparator and a second comparator;

[0012] The first end of the first comparator is the first end of the hysteresis module, the second end of the first comparator is the second end of the hysteresis module, and the first comparator is used to determine a first zero-crossing point of the power grid signal according to the power grid signal and the first threshold voltage, and output a first level signal corresponding to the square wave signal according to the first zero-crossing point;

[0013] The first end of the second comparator is the third end of the hysteresis module, the second end of the second comparator is the fourth end of the hysteresis module, and the second comparator is used to determine the second zero-crossing point of the power grid signal according to the power grid signal and the second threshold voltage, and output the second level signal corresponding to the square wave signal according to the second zero-crossing point.

[0014] Optionally, a third end of the phase-locking module is connected to the second end of the capture module, and the phase-locking module is used to output a second frequency and a second phase corresponding to the grid signal according to the first frequency and the grid signal.

[0015] Optionally, the phase-locking module includes an orthogonal signal construction unit, a coordinate transformation unit, a frequency identification unit and a phase identification unit;

[0016] The first end of the orthogonal signal construction unit is used to input a power grid signal, the second end of the orthogonal signal construction unit is connected to the second end of the capture module, and the orthogonal signal construction unit is used to output an orthogonal signal according to the power grid signal and the first frequency;

[0017] The first end of the coordinate transformation unit is connected to the third end of the orthogonal signal construction unit, and the coordinate transformation unit is used to transform the orthogonal signal into a rotation coordinate signal;

[0018] The first end of the frequency identification unit is connected to the second end of the coordinate transformation unit, and the frequency identification unit is used to output the second frequency according to the rotation coordinate signal;

[0019] The first end of the phase identification unit is connected to the second end of the frequency identification unit, the second end of the phase identification unit is the second end of the phase locking module, and the second end of the phase identification unit is also connected to the third end of the coordinate transformation unit. The phase identification unit is used to determine the second phase according to the second frequency.

[0020] Optionally, the frequency identification unit includes a PID regulator;

[0021] The phase identification unit includes an integrator.

[0022] Optionally, the phase-locking device further includes a signal acquisition module;

[0023] The first end of the signal acquisition module is used to input the power grid signal, the second end of the signal acquisition module is connected to the first end and the third end of the hysteresis module, and the signal acquisition module is used to acquire the power grid signal.

[0024] Optionally, the phase-locking device further includes a signal conditioning module;

[0025] The second end of the signal acquisition module is connected to the first end and the third end of the hysteresis module through the signal conditioning module.

[0026] According to another aspect of the present invention, there is provided a phase-locked control system, the phase-locked control system comprising any phase-locked device as described in the first aspect, and further comprising an inverter;

[0027] The phase-locking device comprises: a hysteresis module, a capture module, a phase-locking module and a fault-tolerant module;

[0028] The first end of the hysteresis module is used to input a power grid signal, the second end of the hysteresis module is used to input a first threshold voltage, the third end of the hysteresis module is used to input a power grid signal, and the fourth end of the hysteresis module is used to input a second threshold voltage, the hysteresis module is used to determine a first zero-crossing point of the power grid signal according to the power grid signal and the first threshold voltage, determine a second zero-crossing point of the power grid signal according to the power grid signal and the second threshold voltage, and output a square wave signal corresponding to the power grid signal according to the first zero-crossing point and the second zero-crossing point;

[0029] The first end of the capture module is connected to the fifth end of the hysteresis module, and the capture module is used to determine the first frequency and the first phase corresponding to the power grid signal according to the square wave signal;

[0030] The first end of the phase locking module is used to input the grid signal, and the phase locking module is used to output the second frequency and the second phase corresponding to the grid signal according to the grid signal;

[0031] The first end of the fault-tolerant module is connected to the second end of the capture module, and the second end of the fault-tolerant module is connected to the second end of the phase-locked module. The fault-tolerant module is used to determine that the first frequency is the grid frequency of the grid signal and the first phase is the grid phase of the grid signal when the difference between the first frequency and the preset frequency is within a preset difference range, and when the difference exceeds the preset difference range, determine that the second frequency is the grid frequency and the second phase is the grid phase;

[0032] The control end of the inverter is connected to the third end of the fault-tolerant module, and the inverter is used to output a next grid signal according to the grid frequency and the grid phase.

[0033] According to another aspect of the present invention, a phase locking method is provided, the phase locking method comprising:

[0034] The hysteresis module determines a first zero-crossing point of the grid signal according to the grid signal and a first threshold voltage, determines a second zero-crossing point of the grid signal according to the grid signal and a second threshold voltage, and outputs a square wave signal corresponding to the grid signal according to the first zero-crossing point and the second zero-crossing point;

[0035] The capture module determines a first frequency and a first phase corresponding to the power grid signal according to the square wave signal;

[0036] The phase locking module outputs a second frequency and a second phase corresponding to the grid signal according to the grid signal;

[0037] The fault-tolerant module determines that the first frequency is the grid frequency of the grid signal and the first phase is the grid phase of the grid signal when the difference between the first frequency and the preset frequency is within a preset difference range; and determines that the second frequency is the grid frequency and the second phase is the grid phase when the difference exceeds the preset difference range.

[0038] Optionally, the hysteresis module determines a first zero-crossing point of the grid signal according to the grid signal and the first threshold voltage, determines a second zero-crossing point of the grid signal according to the grid signal and the second threshold voltage, and outputs a square wave signal corresponding to the grid signal according to the first zero-crossing point and the second zero-crossing point, including:

[0039] Turning on the first comparator and turning off the second comparator, wherein the first comparator determines a first zero-crossing point of the grid signal according to the grid signal and the first threshold voltage, and outputs a first level signal corresponding to the square wave signal according to the first zero-crossing point;

[0040] The second comparator is turned on and the first comparator is turned off. The second comparator determines a second zero-crossing point of the grid signal according to the grid signal and the second threshold voltage, and outputs a second level signal corresponding to the square wave signal according to the second zero-crossing point.

[0041] The technical solution of the embodiment of the present invention can determine the first zero-crossing point by comparing the power grid signal with the first threshold voltage through the hysteresis module, and can determine the second zero-crossing point by comparing the power grid signal with the second threshold voltage, so that the hysteresis module can output the square wave signal corresponding to the power grid signal according to the first zero-crossing point and the second zero-crossing point. The capture module can capture the rising edge of the square wave signal, so that the first frequency and the first phase corresponding to the power grid signal can be determined according to the rising edge, and the phase-locked module can output the second frequency and the second phase corresponding to the power grid signal according to the power grid signal. The fault-tolerant module can make a difference between the first frequency and the preset frequency to obtain a difference, and compare the difference with the preset difference range. If the difference is within the preset difference range, the first frequency output by the capture module can be selected as the grid frequency of the grid signal, and the first phase output by the capture module can be selected as the grid phase of the grid signal; when the difference exceeds the preset difference range, it indicates that the difference is large. At this time, the second frequency output by the phase-locking module can be selected as the grid frequency of the grid signal, and the second phase output by the phase-locking module can be selected as the grid phase of the grid signal. Therefore, a grid frequency and grid phase with a small error can be obtained, so as to facilitate the tracking of the grid signal. According to the grid frequency and grid phase, the inverter can be controlled to achieve synchronization of the grid signal. By combining the capture module with the phase-locking module, a more accurate grid frequency and grid signal can be obtained, the phase-locking error can be reduced, and the accuracy of the phase-locking can be improved. The technical solution of the embodiment of the present invention solves the problem that the phase-locking value deviates from the actual value, resulting in a large phase-locking error, and achieves the effect of reducing the phase-locking error and improving the accuracy of the phase-locking.

[0042] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0044] Figure 1 is a schematic structural diagram of a phase locking device provided by an embodiment of the present invention;

[0045] Figure 2 is a schematic structural diagram of another phase locking device provided by an embodiment of the present invention;

[0046] Figure 3 is a schematic structural diagram of a phase-locked control system provided by an embodiment of the present invention;

[0047] Figure 4 It is a flow chart of a phase locking method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0049] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0050] Figure 1 is a schematic diagram of a phase locking device provided by an embodiment of the present invention, with reference to Figure 1 , the phase-locking device comprises:

[0051] A hysteresis module 101, wherein the first end of the hysteresis module 101 is used to input a power grid signal V0, the second end of the hysteresis module 101 is used to input a first threshold voltage V1, the third end of the hysteresis module 101 is used to input a power grid signal V0, and the fourth end of the hysteresis module 101 is used to input a second threshold voltage V2. The hysteresis module 101 is used to determine a first zero-crossing point of the power grid signal V0 according to the power grid signal V0 and the first threshold voltage V1, determine a second zero-crossing point of the power grid signal V0 according to the power grid signal and the second threshold voltage V2, and output a square wave signal corresponding to the power grid signal V0 according to the first zero-crossing point and the second zero-crossing point;

[0052] A capture module 102, wherein a first end of the capture module 102 is connected to a fifth end of the hysteresis module 101, and the capture module 102 is used to determine a first frequency and a first phase corresponding to the power grid signal V0 according to the square wave signal;

[0053] A phase locking module 103, wherein a first end of the phase locking module 103 is used to input a power grid signal V0, and the phase locking module 103 is used to output a second frequency and a second phase corresponding to the power grid signal V0 according to the power grid signal;

[0054] A fault-tolerant module 104, wherein the first end of the fault-tolerant module 104 is connected to the second end of the capture module 102, and the second end of the fault-tolerant module 104 is connected to the second end of the phase-locked module 103. The fault-tolerant module 104 is used to determine that the first frequency is the grid frequency of the grid signal V0, and the first phase is the grid phase of the grid signal V0 when the difference between the first frequency and the preset frequency is within a preset difference range, and when the difference exceeds the preset difference range, determine that the second frequency is the grid frequency, and the second phase is the grid phase.

[0055] Specifically, the hysteresis module 101 can compare the power grid signal V0 with a first threshold voltage V1, the power grid signal is, for example, a sinusoidal signal, the first threshold voltage V1 is, for example, one-fourth of the peak value of the power grid signal V0, when the hysteresis module 101 determines that the power grid signal V0 is greater than the first threshold voltage V1, the first zero crossing point is output, for example, a positive zero crossing point; the hysteresis module 101 can compare the power grid signal V0 with a second threshold voltage V2, the second threshold voltage V2 is, for example, one-fourth of the trough value of the power grid signal V0, when the hysteresis module 101 determines that the power grid signal V0 is less than the second threshold voltage V2, the second zero crossing point is output, for example, a negative zero crossing point, so that the hysteresis module 101 can output a square wave signal corresponding to the power grid signal V0 according to the first zero crossing point and the second zero crossing point. The capture module 102 can capture the rising edge of the square wave signal, so that the first frequency and the first phase corresponding to the power grid signal V0 can be determined according to the rising edge. The phase-locked module 103 is, for example, a phase-locked loop based on a second-order generalized integrator. The phase-locked module 103 can output the second frequency and the second phase corresponding to the grid signal V0 according to the grid signal V0. The fault-tolerant module 104 can make a difference between the first frequency and the preset frequency to obtain a difference, and compare the difference with the preset difference range. If the difference is within the preset difference range, it indicates that the difference is small, and the first frequency output by the capture module 102 can be selected as the grid frequency of the grid signal V0, and the first phase output by the capture module 102 can be selected as the grid phase of the grid signal V0; when the difference exceeds the preset difference range, it indicates that the difference is large. At this time, the second frequency output by the phase-locked module 103 can be selected as the grid frequency of the grid signal V0, and the second phase output by the phase-locked module 103 can be selected as the grid phase of the grid signal V0. Therefore, a grid frequency and a grid phase with a small error can be obtained, so as to facilitate the tracking of the grid signal V0. The inverter can be controlled according to the grid frequency and the grid phase to achieve synchronization of the grid signal.

[0056] The preset frequency is, for example, a standard frequency of a power grid signal. The preset frequency and the preset difference range can be determined according to specific circumstances and are not limited here.

[0057] By combining the capture module 102 with the phase locking module 103, a more accurate grid frequency and grid signal can be obtained, the phase locking error can be reduced, and the accuracy of the phase locking can be improved.

[0058] In addition, the hysteresis module 101 and the capture module 102 are implemented by, for example, a soft core of a processor, and the phase-locked module 103 and the fault-tolerant module 104 are implemented by, for example, software of a processor. By combining the hardware and software of the processor, the problem of the hardware circuit being sensitive to parameters, which leads to a large phase-locked error, can be avoided, and the accuracy of the phase-locked phase can be further improved.

[0059] The technical solution of this embodiment is that the hysteresis module compares the power grid signal with the first threshold voltage to determine the first zero-crossing point, and the hysteresis module compares the power grid signal with the second threshold voltage to determine the second zero-crossing point, so that the hysteresis module can output a square wave signal corresponding to the power grid signal according to the first zero-crossing point and the second zero-crossing point. The capture module can capture the rising edge of the square wave signal, so that the first frequency and the first phase corresponding to the power grid signal can be determined according to the rising edge, and the phase-locked module can output the second frequency and the second phase corresponding to the power grid signal according to the power grid signal. The fault-tolerant module can make a difference between the first frequency and the preset frequency to obtain a difference, and compare the difference with the preset difference range. If the difference is within the preset difference range, the first frequency output by the capture module can be selected as the grid frequency of the grid signal, and the first phase output by the capture module can be selected as the grid phase of the grid signal; when the difference exceeds the preset difference range, it indicates that the difference is large. At this time, the second frequency output by the phase-locking module can be selected as the grid frequency of the grid signal, and the second phase output by the phase-locking module can be selected as the grid phase of the grid signal. Therefore, a grid frequency and grid phase with a small error can be obtained, so as to facilitate the tracking of the grid signal. According to the grid frequency and grid phase, the inverter can be controlled to achieve synchronization of the grid signal. By combining the capture module with the phase-locking module, a more accurate grid frequency and grid signal can be obtained, the phase-locking error can be reduced, and the accuracy of the phase-locking can be improved. The technical solution of this embodiment solves the problem that the phase-locking value deviates from the actual value, resulting in a large phase-locking error, and achieves the effect of reducing the phase-locking error and improving the accuracy of the phase-locking.

[0060] Figure 2 is a schematic diagram of the structure of another phase locking device provided by an embodiment of the present invention. Figure 2 The hysteresis module 101 includes a first comparator 1011 and a second comparator 1012; the first end of the first comparator 1011 is the first end of the hysteresis module 101, and the second end of the first comparator 1011 is the second end of the hysteresis module 101. The first comparator 1011 is used to determine a first zero-crossing point of the power grid signal V0 according to the power grid signal V0 and the first threshold voltage V1, and output a first level signal corresponding to the square wave signal according to the first zero-crossing point; the first end of the second comparator 1012 is the third end of the hysteresis module, and the second end of the second comparator 1012 is the fourth end of the hysteresis module 101. The second comparator 1012 is used to determine a second zero-crossing point of the power grid signal V0 according to the power grid signal V0 and the second threshold voltage V2, and output a second level signal corresponding to the square wave signal according to the second zero-crossing point.

[0061] Specifically, the first comparator 1011 can compare the power grid signal V0 with the first threshold voltage V1, where the first threshold voltage V1 is, for example, one-fourth of the peak value of the power grid signal V0. When the first comparator 1011 determines that the power grid signal V0 is greater than the first threshold voltage V1, a first zero crossing point is determined, where the first zero crossing point is, for example, a positive zero crossing point. The first comparator 1011 can output a first level signal, where the first level signal is, for example, a high level signal. The second comparator 1012 can compare the power grid signal with the second threshold voltage V2, where the second threshold voltage V2 is, for example, one-fourth of the trough value of the power grid signal V0. When the second comparator 1012 determines that the power grid signal V0 is less than the second threshold voltage V2, a second zero crossing point is determined, where the second zero crossing point is, for example, a negative zero crossing point. The second comparator 1012 can output a second level signal, where the second level signal is, for example, a low level signal, so that the hysteresis module 101 can output a complete square wave signal.

[0062] Furthermore, the first comparator 1011 and the second comparator 1012 will not work at the same time. After the first comparator 1011 outputs a first level signal, the second comparator 1012 is triggered. After the second comparator 1012 outputs a second level signal, the first comparator 1011 is triggered. This can prevent the first comparator 1011 from outputting a first level signal while the second comparator 1012 outputs a second level signal, or prevent the second comparator 1012 from outputting a second level signal while the first comparator 1011 outputs a first level signal. This can prevent the first comparator 1011 or the second comparator 1012 from malfunctioning, thereby outputting a clean square wave signal.

[0063] Optionally, continue to refer to Figure 2 The third end of the phase-locking module 103 is connected to the second end of the capture module 102, and the phase-locking module 103 is used to output a second frequency and a second phase corresponding to the grid signal V0 according to the first frequency and the grid signal V0.

[0064] Specifically, when the phase-locked module 103 determines the second frequency and the second phase of the grid signal V0, it is necessary to input the grid frequency as the feedback frequency to achieve adaptive frequency changes. By using the first frequency output by the capture module 102 as the feedback frequency, a more accurate second frequency and second phase can be obtained. If the second frequency is used as the feedback frequency, when the second frequency error is large, it is easy to cause a larger error, which is not conducive to the stability of the system. Therefore, by using the first frequency output by the capture module 102 as the feedback frequency, the accuracy of the phase lock can be further improved, and the synchronization of the grid signal can be better achieved.

[0065] Optionally, continue to refer to Figure 2The phase-locking module 103 includes an orthogonal signal construction unit 1031, a coordinate transformation unit 1032, a frequency identification unit 1033 and a phase identification unit 1034; the first end of the orthogonal signal construction unit 1031 is used to input the power grid signal V0, the second end of the orthogonal signal construction unit 1031 is connected to the second end of the capture module 102, and the orthogonal signal construction unit 1031 is used to output an orthogonal signal according to the power grid signal and the first frequency; the first end of the coordinate transformation unit 1032 is connected to the third end of the orthogonal signal construction unit 1031, and the coordinate transformation unit 1032 is used to for converting the orthogonal signal into a rotating coordinate signal; the first end of the frequency identification unit 1033 is connected to the second end of the coordinate transformation unit 1032, and the frequency identification unit 1033 is used to output a second frequency according to the rotating coordinate signal; the first end of the phase identification unit 1034 is connected to the second end of the frequency identification unit 1033, the second end of the phase identification unit 1034 is the second end of the phase locking module 103, and the second end of the phase identification unit 1034 is also connected to the third end of the coordinate transformation unit 1032, and the phase identification unit 1034 is used to determine the second phase according to the second frequency.

[0066] Specifically, the orthogonal signal construction unit 1031 can convert the power grid signal V0 into a two-phase stationary coordinate system according to the first frequency to obtain an orthogonal signal, the coordinate transformation unit 1032 can convert the orthogonal signal into a two-phase rotating coordinate system to obtain a rotating coordinate signal, the frequency identification unit 1033 can obtain the second frequency corresponding to the power grid signal V0 through the rotating coordinate signal, and the phase identification unit 1034 can integrate the second frequency to obtain the second phase corresponding to the power grid signal V0. In addition, the phase identification unit 1034 outputs the second phase to the coordinate transformation unit 1032, so that the coordinate transformation unit 1032 can obtain the feedback phase, and can adapt to the change of the adaptive phase, thereby outputting a more accurate rotating coordinate signal, so that the output second frequency and second phase are more accurate.

[0067] Optionally, continue to refer to Figure 2 The frequency identification unit 1033 includes a PID regulator; the phase identification unit 1034 includes an integrator.

[0068] Specifically, the frequency identification unit 1033 includes, for example, a PID regulator, which can obtain corresponding frequency information according to the rotating coordinate signal, thereby outputting a second frequency corresponding to the grid signal. The phase identification unit 1034 includes, for example, an integrator, which can integrate the second frequency, thereby outputting a second phase corresponding to the grid signal V0.

[0069] Optionally, continue to refer to Figure 2The phase-locking device also includes a signal acquisition module 105; the first end of the signal acquisition module 105 is used to input the power grid signal V0, the second end of the signal acquisition module 105 is connected to the first end and the third end of the hysteresis module 101, and the signal acquisition module 105 is used to collect the power grid signal V0.

[0070] Specifically, the signal acquisition module 105 includes, for example, an A / D sampling circuit. The signal acquisition module 105 can acquire the grid signal V0 and send the grid signal V0 to the hysteresis module 101 to obtain the grid frequency and grid phase corresponding to the grid signal.

[0071] Optionally, continue to refer to Figure 2 The phase-locked device further includes a signal conditioning module 106 ; the second end of the signal acquisition module 105 is connected to the first end and the third end of the hysteresis module 101 through the signal conditioning module 106 .

[0072] Specifically, the signal conditioning module 106 can adjust the amplitude of the power grid signal output by the signal acquisition module 105, thereby restoring the real power grid signal V0, and send the adjusted power grid signal to the hysteresis module 101, so that the hysteresis module 101 obtains the real power grid signal V0, which is convenient for obtaining accurate power grid frequency and power grid phase, thereby achieving the effect of further improving the accuracy of phase locking.

[0073] Optionally, the second end of the signal acquisition module 105 is further connected to the first end of the phase locking module 103 via the signal conditioning module 106, so that the phase locking module 103 acquires the power grid signal V0.

[0074] Figure 3 is a schematic diagram of a phase-locked control system provided by an embodiment of the present invention, with reference to Figure 3The phase-locked control system includes the phase-locked device 100 provided by any of the above-mentioned embodiments, and also includes an inverter 200; the phase-locked device includes: a hysteresis module 101, a capture module 102, a phase-locked module 103 and a fault-tolerant module 104; the first end of the hysteresis module 101 is used to input a power grid signal V0, the second end of the hysteresis module 101 is used to input a first threshold voltage V1, the third end of the hysteresis module 101 is used to input a power grid signal V0, the fourth end of the hysteresis module 101 is used to input a second threshold voltage, the hysteresis module 101 is used to determine a first zero-crossing point of the power grid signal V0 according to the power grid signal and the first threshold voltage V1, determine a second zero-crossing point of the power grid signal V0 according to the power grid signal V0 and the second threshold voltage V2, and output a square wave signal corresponding to the power grid signal V0 according to the first zero-crossing point and the second zero-crossing point; the first end of the capture module 102 is connected to the fifth end of the hysteresis module 101, and the capture module 1 02 is used to determine the first frequency and the first phase corresponding to the grid signal V0 according to the square wave signal; the first end of the phase-locked module 103 is used to input the grid signal V0, and the phase-locked module 103 is used to output the second frequency and the second phase corresponding to the grid signal V0 according to the grid signal V0; the first end of the fault-tolerant module 104 is connected to the second end of the capture module 102, and the second end of the fault-tolerant module 104 is connected to the second end of the phase-locked module 103, and the fault-tolerant module 104 is used to determine that the first frequency is the grid frequency of the grid signal V0 and the first phase is the grid phase of the grid signal V0 when the difference between the first frequency and the preset frequency is within the preset difference range, and when the difference exceeds the preset difference range, determine that the second frequency is the grid frequency and the second phase is the grid phase; the control end of the inverter 200 is connected to the third end of the fault-tolerant module 104, and the inverter 200 is used to output the next grid signal according to the grid frequency and the grid phase.

[0075] The phase-locking system provided in this embodiment includes the phase-locking device of any of the above implementation schemes. The implementation principle and technical effects of the phase-locking system provided in this embodiment are the same as those of the above implementation schemes, and will not be repeated here.

[0076] Figure 4 is a flow chart of a phase locking method provided by an embodiment of the present invention, refer to Figure 4 , the phase-locking methods include:

[0077] S410, the hysteresis module determines a first zero-crossing point of the grid signal according to the grid signal and the first threshold voltage, determines a second zero-crossing point of the grid signal according to the grid signal and the second threshold voltage, and outputs a square wave signal corresponding to the grid signal according to the first zero-crossing point and the second zero-crossing point.

[0078] Specifically, refer to Figure 1The hysteresis module 101 can compare the power grid signal V0 with a first threshold voltage V1, where the power grid signal V0 is, for example, a sinusoidal signal, and the first threshold voltage V1 is, for example, one-fourth of the peak value of the power grid signal V0. When the hysteresis module 101 determines that the power grid signal V0 is greater than the first threshold voltage V1, it outputs a first zero-crossing point, where the first zero-crossing point is, for example, a positive zero-crossing point; the hysteresis module 101 can compare the power grid signal V0 with a second threshold voltage V2, where the second threshold voltage V2 is, for example, one-fourth of the trough value of the power grid signal V0. When the hysteresis module 101 determines that the power grid signal V0 is less than the second threshold voltage V2, it outputs a second zero-crossing point, where the second zero-crossing point is, for example, a negative zero-crossing point, so that the hysteresis module 101 can output a square wave signal corresponding to the power grid signal V0 according to the first zero-crossing point and the second zero-crossing point.

[0079] S420. The capture module determines a first frequency and a first phase corresponding to the power grid signal according to the square wave signal.

[0080] Specifically, refer to Figure 1 The capture module 102 can capture the rising edge of the square wave signal, so that the first frequency and the first phase corresponding to the power grid signal can be determined according to the rising edge.

[0081] S430. The phase-locking module outputs a second frequency and a second phase corresponding to the grid signal according to the grid signal.

[0082] Specifically, refer to Figure 1 The phase-locked module 103 is, for example, a phase-locked loop based on a second-order generalized integrator. The phase-locked module 103 can output a second frequency and a second phase corresponding to the grid signal V0 according to the grid signal V0.

[0083] S440, the fault-tolerant module determines that the first frequency is the grid frequency of the grid signal and the first phase is the grid phase of the grid signal when the difference between the first frequency and the preset frequency is within the preset difference range; when the difference exceeds the preset difference range, the fault-tolerant module determines that the second frequency is the grid frequency and the second phase is the grid phase.

[0084] Specifically, refer to Figure 1, the fault-tolerant module 104 can make a difference between the first frequency and the preset frequency to obtain a difference, and compare the difference with the preset difference range. If the difference is within the preset difference range, it indicates that the difference is small, and the first frequency output by the capture module 102 can be selected as the grid frequency of the grid signal V0, and the first phase output by the capture module 102 can be selected as the grid phase of the grid signal V0; when the difference exceeds the preset difference range, it indicates that the difference is large. At this time, the second frequency output by the phase-locking module 103 can be selected as the grid frequency of the grid signal V0, and the second phase output by the phase-locking module 103 can be selected as the grid phase of the grid signal V0. Therefore, a grid frequency and grid phase with a small error can be obtained, so as to facilitate the tracking of the grid signal. According to the grid frequency and grid phase, the inverter can be controlled to achieve synchronization of the grid signal. By combining the capture module 102 with the phase-locking module 103, a more accurate grid frequency and grid signal can be obtained, the phase-locking error can be reduced, and the accuracy of the phase-locking can be improved.

[0085] On the basis of the above technical solution, S410, the hysteresis module determines the first zero-crossing point of the grid signal according to the grid signal and the first threshold voltage, determines the second zero-crossing point of the grid signal according to the grid signal and the second threshold voltage, and outputs a square wave signal corresponding to the grid signal according to the first zero-crossing point and the second zero-crossing point, including:

[0086] Step a, turning on the first comparator and turning off the second comparator, the first comparator determines the first zero-crossing point of the grid signal according to the grid signal and the first threshold voltage, and outputs a first level signal corresponding to the square wave signal according to the first zero-crossing point.

[0087] Specifically, refer to Figure 2 , the first comparator 1011 can compare the power grid signal V0 with the first threshold voltage V1, the first threshold voltage V1 is, for example, one quarter of the peak value of the power grid signal V0, when the first comparator 1011 determines that the power grid signal V0 is greater than the first threshold voltage V1, the first zero crossing point is determined, the first zero crossing point is, for example, a positive zero crossing point, and the first comparator 1011 can output a first level signal, the first level signal is, for example, a high level signal. And when the first comparator 1011 is turned on, the second comparator 1012 is turned off, so that the second comparator 1012 can be prevented from outputting a second level signal during the process of the first comparator 1011 outputting a first level signal, so that the second comparator 1012 can be prevented from malfunctioning, thereby facilitating the output of a clean square wave signal.

[0088] Step b, turning on the second comparator and turning off the first comparator, the second comparator determines the second zero-crossing point of the grid signal according to the grid signal and the second threshold voltage, and outputs a second level signal corresponding to the square wave signal according to the second zero-crossing point.

[0089] Specifically, refer to Figure 2 , the second comparator 1012 can compare the power grid signal V0 with the second threshold voltage V2, the second threshold voltage V2 is, for example, one-fourth of the valley value of the power grid signal V0, when the second comparator 1012 determines that the power grid signal V0 is less than the second threshold voltage V2, the second zero crossing point is determined, the second zero crossing point is, for example, a negative zero crossing point, the second comparator 1012 can output a second level signal, the second level signal is, for example, a low level signal, so that the hysteresis module 101 can output a complete square wave signal. After the first comparator 1011 outputs the first level signal, the second comparator 1012 is triggered again, and when the second comparator 1012 is turned on, the first comparator 1011 is turned off, so that the first comparator 1011 can avoid outputting the first level signal during the process of the second comparator 1012 outputting the second level signal, so that the first comparator 1011 can avoid malfunction, thereby facilitating the output of a clean square wave signal.

[0090] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0091] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A phase locking device, characterized in that: include: A hysteresis module, wherein the first end of the hysteresis module is used to input a power grid signal, the second end of the hysteresis module is used to input a first threshold voltage, the third end of the hysteresis module is used to input a power grid signal, and the fourth end of the hysteresis module is used to input a second threshold voltage, the hysteresis module is used to determine a first zero-crossing point of the power grid signal according to the power grid signal and the first threshold voltage, determine a second zero-crossing point of the power grid signal according to the power grid signal and the second threshold voltage, and output a square wave signal corresponding to the power grid signal according to the first zero-crossing point and the second zero-crossing point; A capture module, wherein a first end of the capture module is connected to a fifth end of the hysteresis module, and the capture module is used to determine a first frequency and a first phase corresponding to the power grid signal according to the square wave signal; A phase-locking module, wherein a first end of the phase-locking module is used to input the grid signal, and the phase-locking module is used to output a second frequency and a second phase corresponding to the grid signal according to the grid signal; A fault-tolerant module, wherein a first end of the fault-tolerant module is connected to a second end of the capture module, and a second end of the fault-tolerant module is connected to a second end of the phase-locked module, and the fault-tolerant module is used to determine that the first frequency is the grid frequency of the grid signal and the first phase is the grid phase of the grid signal when the difference between the first frequency and the preset frequency is within a preset difference range, and when the difference exceeds the preset difference range, determine that the second frequency is the grid frequency and the second phase is the grid phase; The third end of the phase-locking module is connected to the second end of the capture module, and the phase-locking module is used to output a second frequency and a second phase corresponding to the grid signal according to the first frequency and the grid signal; The phase-locking module includes an orthogonal signal construction unit, a coordinate transformation unit, a frequency identification unit and a phase identification unit; The first end of the orthogonal signal construction unit is used to input a power grid signal, the second end of the orthogonal signal construction unit is connected to the second end of the capture module, and the orthogonal signal construction unit is used to output an orthogonal signal according to the power grid signal and the first frequency; The first end of the coordinate transformation unit is connected to the third end of the orthogonal signal construction unit, and the coordinate transformation unit is used to transform the orthogonal signal into a rotation coordinate signal; The first end of the frequency identification unit is connected to the second end of the coordinate transformation unit, and the frequency identification unit is used to output the second frequency according to the rotation coordinate signal; The first end of the phase identification unit is connected to the second end of the frequency identification unit, the second end of the phase identification unit is the second end of the phase locking module, and the second end of the phase identification unit is also connected to the third end of the coordinate transformation unit. The phase identification unit is used to determine the second phase according to the second frequency.

2. The phase locking device according to claim 1, characterized in that: The hysteresis module includes a first comparator and a second comparator; The first end of the first comparator is the first end of the hysteresis module, the second end of the first comparator is the second end of the hysteresis module, and the first comparator is used to determine a first zero-crossing point of the power grid signal according to the power grid signal and the first threshold voltage, and output a first level signal corresponding to the square wave signal according to the first zero-crossing point; The first end of the second comparator is the third end of the hysteresis module, the second end of the second comparator is the fourth end of the hysteresis module, and the second comparator is used to determine the second zero-crossing point of the power grid signal according to the power grid signal and the second threshold voltage, and output the second level signal corresponding to the square wave signal according to the second zero-crossing point.

3. The phase locking device according to claim 1, characterized in that: The frequency identification unit includes a PID regulator; The phase identification unit includes an integrator.

4. The phase locking device according to claim 1, characterized in that: Also includes a signal acquisition module; The first end of the signal acquisition module is used to input the power grid signal, the second end of the signal acquisition module is connected to the first end and the third end of the hysteresis module, and the signal acquisition module is used to acquire the power grid signal.

5. The phase locking device according to claim 4, characterized in that: Also included are signal conditioning modules; The second end of the signal acquisition module is connected to the first end and the third end of the hysteresis module through the signal conditioning module.

6. A phase-locked control system, characterized in that: A phase locking device comprising any one of claims 1 to 5, further comprising an inverter; The phase-locking device comprises: a hysteresis module, a capture module, a phase-locking module and a fault-tolerant module; The first end of the hysteresis module is used to input a power grid signal, the second end of the hysteresis module is used to input a first threshold voltage, the third end of the hysteresis module is used to input a power grid signal, and the fourth end of the hysteresis module is used to input a second threshold voltage, the hysteresis module is used to determine a first zero-crossing point of the power grid signal according to the power grid signal and the first threshold voltage, determine a second zero-crossing point of the power grid signal according to the power grid signal and the second threshold voltage, and output a square wave signal corresponding to the power grid signal according to the first zero-crossing point and the second zero-crossing point; The first end of the capture module is connected to the fifth end of the hysteresis module, and the capture module is used to determine the first frequency and the first phase corresponding to the power grid signal according to the square wave signal; The first end of the phase locking module is used to input the grid signal, and the phase locking module is used to output the second frequency and the second phase corresponding to the grid signal according to the grid signal; The first end of the fault-tolerant module is connected to the second end of the capture module, and the second end of the fault-tolerant module is connected to the second end of the phase-locked module. The fault-tolerant module is used to determine that the first frequency is the grid frequency of the grid signal and the first phase is the grid phase of the grid signal when the difference between the first frequency and the preset frequency is within a preset difference range, and when the difference exceeds the preset difference range, determine that the second frequency is the grid frequency and the second phase is the grid phase; The third end of the phase-locking module is connected to the second end of the capture module, and the phase-locking module is used to output a second frequency and a second phase corresponding to the grid signal according to the first frequency and the grid signal; The phase-locking module includes an orthogonal signal construction unit, a coordinate transformation unit, a frequency identification unit and a phase identification unit; The first end of the orthogonal signal construction unit is used to input a power grid signal, the second end of the orthogonal signal construction unit is connected to the second end of the capture module, and the orthogonal signal construction unit is used to output an orthogonal signal according to the power grid signal and the first frequency; The first end of the coordinate transformation unit is connected to the third end of the orthogonal signal construction unit, and the coordinate transformation unit is used to transform the orthogonal signal into a rotation coordinate signal; The first end of the frequency identification unit is connected to the second end of the coordinate transformation unit, and the frequency identification unit is used to output the second frequency according to the rotation coordinate signal; The first end of the phase identification unit is connected to the second end of the frequency identification unit, the second end of the phase identification unit is the second end of the phase locking module, the second end of the phase identification unit is also connected to the third end of the coordinate transformation unit, and the phase identification unit is used to determine the second phase according to the second frequency; The control end of the inverter is connected to the third end of the fault-tolerant module, and the inverter is used to output a next grid signal according to the grid frequency and the grid phase.

7. A phase locking method, characterized in that: A phase locking device as claimed in any one of claims 1 to 5; The phase locking method comprises: The hysteresis module determines a first zero-crossing point of the grid signal according to the grid signal and a first threshold voltage, determines a second zero-crossing point of the grid signal according to the grid signal and a second threshold voltage, and outputs a square wave signal corresponding to the grid signal according to the first zero-crossing point and the second zero-crossing point; The capture module determines a first frequency and a first phase corresponding to the power grid signal according to the square wave signal; The phase locking module outputs a second frequency and a second phase corresponding to the grid signal according to the grid signal; The fault-tolerant module determines that the first frequency is the grid frequency of the grid signal and the first phase is the grid phase of the grid signal when the difference between the first frequency and the preset frequency is within a preset difference range; and determines that the second frequency is the grid frequency and the second phase is the grid phase when the difference exceeds the preset difference range.

8. The phase locking method according to claim 7, characterized in that: The hysteresis module determines a first zero-crossing point of the grid signal according to the grid signal and the first threshold voltage, determines a second zero-crossing point of the grid signal according to the grid signal and the second threshold voltage, and outputs a square wave signal corresponding to the grid signal according to the first zero-crossing point and the second zero-crossing point, including: Turning on the first comparator and turning off the second comparator, wherein the first comparator determines a first zero-crossing point of the grid signal according to the grid signal and the first threshold voltage, and outputs a first level signal corresponding to the square wave signal according to the first zero-crossing point; The second comparator is turned on and the first comparator is turned off. The second comparator determines a second zero-crossing point of the grid signal according to the grid signal and the second threshold voltage, and outputs a second level signal corresponding to the square wave signal according to the second zero-crossing point.

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