Power electronic converter power grid voltage phase locking method, device and equipment

Abstract

The invention discloses a power electronic converter power grid voltage phase locking method, device and equipment, and the method comprises the steps: employing an output signal of a three-phase phase-locked loop in a normal power system fluctuation range, considering that a power grid is abnormal when the output signal exceeds the normal power system fluctuation range, carrying out the phase and frequency weighting based on the output signal of the three-phase phase-locked loop, and carrying out the phase locking of the output signal of the three-phase phase-locked loop; an internal phase-locked signal is constructed to track and calculate the phase and frequency of a normal range and is switched to the internal phase-locked signal output, the output phase-locked signal is more stable, the power grid voltage phase-locked output is not influenced by power grid fluctuation and is not easy to lose stability, meanwhile, a power grid phase-locked abnormity mark is given, a power electronic converter control system is prompted to limit the working current in time, and the reliability of the power electronic converter is improved. The technical problems that a phase-locked loop of an existing grid-following type converter is easily influenced by power grid fluctuation, control fluctuation and even instability of a power electronic converter are caused, and overcurrent off-grid occurs are solved.

Description

Technical Field

[0001] The present invention relates to the field of phase locking technology, and in particular to a method, device and equipment for phase locking of power electronic converter grid voltage. Background Art

[0002] Grid-connected power electronic converters require the support of the power system to connect to the grid. The existing power system is composed of generator groups, power grids, and power electronic converters. The frequency and phase of the generator group will not change suddenly, but the power grid is not stable. In the case of single-phase, two-phase, and three-phase faults, such as high voltage ride-through and low voltage ride-through, phase mutations will occur and the phase-locked loop will fluctuate. In some extreme fault conditions, due to the abnormality of the power grid itself, the fluctuation caused by the phase-locked loop of the grid-connected converter will cause the power electronic converter control to fluctuate or even become unstable, resulting in overcurrent and disconnection of the power electronic converter from the grid. Summary of the invention

[0003] The present invention provides a method, device and equipment for phase-locking the grid voltage of a power electronic converter, which is used to solve the technical problem that the existing grid-following converter phase-locked loop is easily affected by grid fluctuations, resulting in control fluctuations or even instability of the power electronic converter, and overcurrent and grid disconnection.

[0004] In view of this, a first aspect of the present invention provides a power electronic converter grid voltage phase locking method, comprising:

[0005] S1, obtain the output signal of the three-phase phase-locked loop;

[0006] S2, converting the output signal of the three-phase phase-locked loop into a square wave signal;

[0007] S3, judging whether the square wave signal is normal according to the preset power system stability range domain, if so, executing step S4, otherwise, executing step S5, the preset power system stability range domain includes frequency domain, period domain and phase domain;

[0008] S4, output the output signal of the three-phase phase-locked loop;

[0009] S5, using a sliding window to perform linear weighted calculation on the phase value of the output signal of the three-phase phase-locked loop to obtain a weighted phase value, using a sliding window to perform linear weighted calculation on the frequency value of the output signal of the three-phase phase-locked loop to obtain a weighted frequency value, and executing step S6;

[0010] S6. According to the weighted phase value and the weighted frequency value, the output signal of the three-phase phase-locked loop is synthesized into an inner phase-locked signal for output and a phase-locked abnormal signal is identified.

[0011] Optionally, step S3 specifically includes:

[0012] Record the period average value Tavg0 and period error range dT of the square wave signal within the preset time. Within the period range Tavg0-dT to Tavg0+dT, for the first periodic signal, determine whether the square wave signal is a normal signal based on whether the frequency of the square wave signal is between 48Hz and 51.5Hz, whether the frequency change rate does not exceed 0.2Hz / s, and whether the phase does not suddenly change. For non-first periodic signals, if the previous periodic signal is a normal signal, then compared with the previous periodic signal, the continuous periodic change is less than the preset duration, then the signal period is considered normal, and step S4 is executed; if the continuous periodic change is not less than the preset duration, then the period is considered abnormal, and step S5 is executed; if the previous periodic signal is an abnormal signal, then compared with the previous periodic signal, the continuous periodic change is less than the preset duration + dT, then the signal period is considered normal, and step S4 is executed; if the continuous periodic change is not less than the preset duration + dT, then the period is considered abnormal, and step S5 is executed, wherein the preset time covers multiple signal periods.

[0013] Optionally, the preset duration is 1.6us.

[0014] Optionally, the preset time is 30s.

[0015] Optionally, step S3 further includes:

[0016] It is determined whether the cumulative time of the square wave signal judged as an abnormal signal within 10s exceeds 2s. If so, the square wave signal after the cumulative time exceeds 2s within the preset time is forcibly set as a normal signal.

[0017] Optionally, in step S5, the calculation formula of the weighted phase value is:

[0018]

[0019] in, is the weighted phase value, is the phase value of n moments arranged in reverse time order, for One-to-one corresponding phase weight value, The value decreases linearly between [0,1].

[0020] Optionally, in step S5, the calculation formula of the weighted frequency value is:

[0021]

[0022] in, is the weighted frequency value, is the frequency value of n moments arranged in reverse chronological order, for One-to-one corresponding frequency weight values, The value decreases linearly between [0,1].

[0023] A second aspect of the present invention provides a power electronic converter grid voltage phase locking device, comprising: a three-phase phase-locked loop, an internal phase-locked signal building module and a comprehensive judgment output module;

[0024] The three-phase phase-locked loop is connected to the internal phase-locked signal construction module, and the three-phase phase-locked loop and the internal phase-locked signal construction module are respectively connected to the comprehensive judgment output module;

[0025] A three-phase phase-locked loop is used to obtain a three-phase signal from a three-phase power supply, process the three-phase signal, and output a three-phase external phase-locked signal;

[0026] An inner phase-locked signal construction module is used to obtain the output signal of the three-phase phase-locked loop, convert the output signal of the three-phase phase-locked loop into a square wave signal, and is also used to perform linear weighted calculation on the phase value of the output signal of the three-phase phase-locked loop using a sliding window to obtain a weighted phase value, and to perform linear weighted calculation on the frequency value of the output signal of the three-phase phase-locked loop using a sliding window to obtain a weighted frequency value, and according to the weighted phase value and the weighted frequency value, synthesize the output signal of the three-phase phase-locked loop into an inner phase-locked signal for output and identify a phase-locked abnormality signal;

[0027] The comprehensive judgment output module is used to judge whether the square wave signal is normal according to the preset power system stability range domain. If so, the output signal of the three-phase phase-locked loop is output; otherwise, the inner phase-locked signal synthesized by the inner phase-locked signal construction module is output. The preset power system stability range domain includes frequency domain, period domain and phase domain.

[0028] Optionally, the root comprehensive judgment output module is specifically used for:

[0029] Record the period average value Tavg0 and period error range dT of the square wave signal within the preset time. Within the period range Tavg0-dT to Tavg0+dT, for the first periodic signal, determine whether the square wave signal is a normal signal based on whether the frequency of the square wave signal is between 48Hz and 51.5Hz, whether the frequency change rate does not exceed 0.2Hz / s, and whether the phase does not suddenly change. For non-first periodic signals, if the previous periodic signal is a normal signal, then compared with the previous periodic signal, the continuous periodic change is less than the preset duration, then the signal period is considered normal, and step S4 is executed; if the continuous periodic change is not less than the preset duration, then the period is considered abnormal, and step S5 is executed; if the previous periodic signal is an abnormal signal, then compared with the previous periodic signal, the continuous periodic change is less than the preset duration + dT, then the signal period is considered normal, and step S4 is executed; if the continuous periodic change is not less than the preset duration + dT, then the period is considered abnormal, and step S5 is executed, wherein the preset time covers multiple signal periods.

[0030] Optionally, in the inner phase-locked signal building module, the calculation formula of the weighted phase value is:

[0031]

[0032] in, is the weighted phase value, is the phase value of n moments arranged in reverse time order, for One-to-one corresponding phase weight value, The value decreases linearly between [0,1];

[0033] The formula for calculating the weighted frequency value is:

[0034]

[0035] in, is the weighted frequency value, is the frequency value of n moments arranged in reverse chronological order, for One-to-one corresponding frequency weight values, The value decreases linearly between [0,1].

[0036] A third aspect of the present invention provides a power electronic converter grid voltage phase locking device, the device comprising a processor and a memory:

[0037] The memory is used to store program code and transmit the program code to the processor;

[0038] The processor is used to execute the power electronic converter grid voltage phase locking method described in any one of the first aspects according to the instructions in the program code.

[0039] It can be seen from the above technical solutions that the power electronic converter grid voltage phase locking method provided by the present invention has the following advantages:

[0040] The power electronic converter grid voltage phase-locking method provided by the present invention adopts the output signal of the three-phase phase-locked loop within the normal power system fluctuation range. When it exceeds the normal power system fluctuation range, it is considered that the grid is abnormal, and phase and frequency weighting is performed based on the output signal of the three-phase phase-locked loop, and an inner phase-locked signal is constructed to track and calculate the phase and frequency in the normal range, and the inner phase-locked signal is switched to output. The output phase-locked signal is more stable, and the grid voltage phase-locked output is not affected by grid fluctuations and is not easy to become unstable. At the same time, a grid phase-locked abnormality mark is given to prompt the power electronic converter control system to limit the working current in time, so as to solve the technical problem that the existing grid-following converter phase-locked loop is easily affected by grid fluctuations, resulting in power electronic converter control fluctuations or even instability, and overcurrent disconnection. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 A schematic diagram of a flow chart of a power electronic converter grid voltage phase locking method provided in the present invention;

[0043] Figure 2 A schematic diagram of a power electronic converter grid voltage phase locking method provided in the present invention;

[0044] Figure 3 A logic block diagram of a power electronic converter grid voltage phase locking method provided in the present invention;

[0045] Figure 4 The present invention is a schematic structural diagram of a power electronic converter grid voltage phase locking device provided in the present invention. DETAILED DESCRIPTION

[0046] 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 are within the scope of protection of the present invention.

[0047] For easier understanding, see Figures 1 to 3 The present invention provides an embodiment of a three-power electronic converter grid voltage phase locking method, comprising:

[0048] Step S1, obtaining the output signal of the three-phase phase-locked loop.

[0049] It should be noted that the three-phase phase-locked loop is mainly used to detect and track the phase of the three-phase voltage or current signal to ensure that the system can be correctly synchronized with the power grid or other power sources, thereby ensuring the stability and reliability of the system. Conventional three-phase phase-locked loops include synchronous reference frame phase-locked loops (SRF-PLL), enhanced phase-locked loops (EPLL), phase-locked loops based on Clarke transforms, and second order generalized integrator phase-locked loops (SOGI-PLL). Figure 2 and Figure 3 As shown, in the embodiment of the present invention, the output signal of the three-phase phase-locked loop is first obtained, which can be recorded as signal 2.

[0050] Step S2: convert the output signal of the three-phase phase-locked loop into a square wave signal.

[0051] It should be noted that the output signal of the three-phase phase-locked loop is converted into a square wave signal with a duty cycle of 50% according to the period information.

[0052] Step S3, judging whether the square wave signal is normal according to the preset power system stability range domain, if so, executing step S4, otherwise, executing step S5, the preset power system stability range domain includes frequency domain, period domain and phase domain.

[0053] It should be noted that the power electronic converter used in the power system should have a stable range of domains under normal working conditions, including frequency domain, period domain and phase domain. If the square wave signal meets the preset power system stable range domain, the square wave signal is normal, otherwise, the square wave signal is abnormal.

[0054] Specifically, the process of determining whether the square wave signal is abnormal is as follows:

[0055] Record the period average value Tavg0 and period error range dT of the square wave signal within the preset time (the preset time covers multiple signal cycles, for example, a total of 1500 signal cycle data within 30s). The period error range dT=2×dT0, dT0 is the positive and negative error value when the data within the preset time is covered for more than 80%. Within the period range Tavg0-dT to Tavg0+dT, for the first period signal, determine whether the square wave signal is a normal signal based on whether the frequency of the square wave signal is between 48Hz and 51.5Hz, whether the frequency change rate does not exceed 0.2Hz / s, and whether the phase does not suddenly change. If the frequency of the square wave signal is between 48Hz and 51.5Hz, the frequency change rate does not exceed 0.2Hz / s, and the phase does not suddenly change, the period signal is considered normal; otherwise, the period signal is considered abnormal. For non-first periodic signals, if the previous periodic signal is a normal signal, then compared with the previous periodic signal, the continuous periodic change is less than the preset time length, then the signal period is considered normal, and step S4 is executed; if the continuous periodic change is not less than the preset time length, then the period is considered abnormal, and step S5 is executed. If the previous periodic signal is an abnormal signal, then compared with the previous periodic signal, the continuous periodic change is less than the preset time length + dT, then the signal period is considered normal, and step S4 is executed; if the continuous periodic change is not less than the preset time length + dT, then the period is considered abnormal, and step S5 is executed.

[0056] In one embodiment, the preset time length is 1.6us. To avoid system overload or misjudgment due to long-term accumulation of abnormal signals, in step S3, Figure 3 As shown, when a square wave signal abnormality occurs, it is necessary to determine whether the cumulative time of the square wave signal judged as an abnormal signal within 10s exceeds 2s. If so, the square wave signal after the cumulative time exceeds 2s within the preset time is forcibly set as a normal signal.

[0057] Step S4: output the output signal of the three-phase phase-locked loop.

[0058] It should be noted that if the square wave signal is normal, the output signal of the three-phase phase-locked loop is directly output.

[0059] Step S5, use a sliding window to perform linear weighted calculation on the phase value of the output signal of the three-phase phase-locked loop to obtain a weighted phase value, use a sliding window to perform linear weighted calculation on the frequency value of the output signal of the three-phase phase-locked loop to obtain a weighted frequency value, and execute step S6.

[0060] It should be noted that if the square wave signal is abnormal, a sliding window is used to perform phase linear weighted calculation on the phase value of the output signal of the three-phase phase-locked loop to obtain a weighted phase value, and a sliding window is used to perform frequency linear weighted calculation on the frequency value of the output signal of the three-phase phase-locked loop to obtain a weighted frequency value. When a sliding window is used to perform weighted calculation on the phase value, the weight of the phase value closer to the current moment is greater, and the weight of the historical phase value farther from the current moment is smaller. The phase value is calculated by comprehensive weighting to ensure the stability and timeliness of the phase. When a sliding window is used to perform weighted calculation on the frequency value, the weight of the frequency value closer to the current moment is greater, and the weight of the historical frequency value farther from the current moment is smaller. The frequency value is calculated by comprehensive weighting to ensure the stability and timeliness of the frequency.

[0061] The calculation formula of the weighted phase value is:

[0062]

[0063] in, is the weighted phase value, is the phase value of n moments arranged in reverse time order, for One-to-one corresponding phase weight value, The value decreases linearly between [0,1].

[0064] For example, the nearest phase value Weight ratio is 1, 5s ago The weight ratio is 0, the intermediate phase Calculate according to linear weight (for example, 2.5s before the phase The weight is 0.5).

[0065] The formula for calculating the weighted frequency value is:

[0066]

[0067] in, is the weighted frequency value, is the frequency value of n moments arranged in reverse chronological order, for One-to-one corresponding frequency weight values, The value decreases linearly between [0,1].

[0068] For example, the nearest phase value Weight ratio is 1, 5s ago The weight ratio is 0, the intermediate phase Calculate according to linear weight (for example, 2.5s before the phase The weight is 0.5)

[0069] Step S6: According to the weighted phase value and the weighted frequency value, the output signal of the three-phase phase-locked loop is synthesized into an inner phase-locked signal for output and a phase-locked abnormal signal is identified.

[0070] It should be noted that after the weighted phase value and the weighted frequency value are calculated, the weighted phase value and the weighted frequency value are used as the phase value and the frequency value of the output signal of the three-phase phase-locked loop, and the internal phase-locked signal is synthesized and output, such as Figure 3 As shown, the internal phase-locked signal can be recorded as signal 1. While outputting the internal phase-locked signal, a grid phase-locked abnormal signal is given to indicate that the power electronic converter control system should limit the operating current in time. Figure 2 As shown, in the embodiment of the present invention, the comprehensive judgment output module needs to decide whether to directly output the output signal of the three-phase phase-locked loop according to whether the output signal of the three-phase phase-locked loop obtained is abnormal. Figure 3 , two control quantities of 1 and 0 can be set in the comprehensive judgment output module. If the output signal of the three-phase phase-locked loop is within the normal range, the control quantity of the comprehensive judgment output module is 1, and the output signal of the three-phase phase-locked loop is directly used, that is, the comprehensive judgment output module selects signal 2 for output; if the output signal of the three-phase phase-locked loop is abnormal, the control quantity of the comprehensive judgment output module is 0, and the internal phase-locked signal is used for output, that is, the comprehensive judgment output module selects signal 1 for output.

[0071] The power electronic converter grid voltage phase-locking method provided by the present invention adopts the output signal of the three-phase phase-locked loop within the normal power system fluctuation range. When it exceeds the normal power system fluctuation range, it is considered that the grid is abnormal, and phase and frequency weighting is performed based on the output signal of the three-phase phase-locked loop, and an inner phase-locked signal is constructed to track and calculate the phase and frequency in the normal range, and the inner phase-locked signal is switched to output. The output phase-locked signal is more stable, and the grid voltage phase-locked output is not affected by grid fluctuations and is not easy to become unstable. At the same time, a grid phase-locked abnormality mark is given to prompt the power electronic converter control system to limit the working current in time, so as to solve the technical problem that the existing grid-following converter phase-locked loop is easily affected by grid fluctuations, resulting in power electronic converter control fluctuations or even instability, and overcurrent disconnection.

[0072] For easier understanding, see Figure 4 , the present invention provides an embodiment of a power electronic converter grid voltage phase-locking device, comprising: a three-phase phase-locked loop, an internal phase-locked signal building module and a comprehensive judgment output module;

[0073] The three-phase phase-locked loop is connected to the internal phase-locked signal construction module, and the three-phase phase-locked loop and the internal phase-locked signal construction module are respectively connected to the comprehensive judgment output module;

[0074] A three-phase phase-locked loop is used to obtain a three-phase signal from a three-phase power supply, process the three-phase signal, and output a three-phase external phase-locked signal;

[0075] An inner phase-locked signal construction module is used to obtain the output signal of the three-phase phase-locked loop, convert the output signal of the three-phase phase-locked loop into a square wave signal, and is also used to perform linear weighted calculation on the phase value of the output signal of the three-phase phase-locked loop using a sliding window to obtain a weighted phase value, and to perform linear weighted calculation on the frequency value of the output signal of the three-phase phase-locked loop using a sliding window to obtain a weighted frequency value, and according to the weighted phase value and the weighted frequency value, synthesize the output signal of the three-phase phase-locked loop into an inner phase-locked signal for output and identify a phase-locked abnormality signal;

[0076] The comprehensive judgment output module is used to judge whether the square wave signal is normal according to the preset power system stability range domain. If so, the output signal of the three-phase phase-locked loop is output; otherwise, the inner phase-locked signal synthesized by the inner phase-locked signal construction module is output. The preset power system stability range domain includes frequency domain, period domain and phase domain.

[0077] In one embodiment, the comprehensive judgment output module is specifically used for:

[0078] Record the period average value Tavg0 and period error range dT of the square wave signal within the preset time. Within the period range Tavg0-dT to Tavg0+dT, for the first periodic signal, determine whether the square wave signal is a normal signal based on whether the frequency of the square wave signal is between 48Hz and 51.5Hz, whether the frequency change rate does not exceed 0.2Hz / s, and whether the phase does not suddenly change. For non-first periodic signals, if the previous periodic signal is a normal signal, then compared with the previous periodic signal, the continuous periodic change is less than the preset duration, then the signal period is considered normal, and step S4 is executed; if the continuous periodic change is not less than the preset duration, then the period is considered abnormal, and step S5 is executed; if the previous periodic signal is an abnormal signal, then compared with the previous periodic signal, the continuous periodic change is less than the preset duration + dT, then the signal period is considered normal, and step S4 is executed; if the continuous periodic change is not less than the preset duration + dT, then the period is considered abnormal, and step S5 is executed, wherein the preset time covers multiple signal periods.

[0079] In one embodiment, the calculation formula of the weighted phase value is:

[0080]

[0081] in, is the weighted phase value, is the phase value of n moments arranged in reverse time order, for One-to-one corresponding phase weight value, The value decreases linearly between [0,1];

[0082] In one embodiment, the calculation formula of the weighted frequency value is:

[0083]

[0084] in, is the weighted phase value, is the frequency value of n moments arranged in reverse chronological order, for One-to-one corresponding frequency weight values, The value decreases linearly between [0,1].

[0085] In one embodiment, the preset duration is 1.6 us.

[0086] In one embodiment, the preset time is 30 seconds. The comprehensive judgment output module is also used for:

[0087] It is determined whether the cumulative time of the square wave signal judged as an abnormal signal within 10s exceeds 2s. If so, the square wave signal after the cumulative time exceeds 2s within the preset time is forcibly set as a normal signal.

[0088] The present invention provides an embodiment of a power electronic converter grid voltage phase locking device, the device comprising a processor and a memory:

[0089] The memory is used to store program code and transmit the program code to the processor;

[0090] The processor is used to execute the power electronic converter grid voltage phase locking method provided in the present invention according to the instructions in the program code.

[0091] The power electronic converter grid voltage phase-locking device and equipment provided in the present invention are used to execute the power electronic converter grid voltage phase-locking method provided in the present invention. The principle and technical effects achieved are the same as those of the power electronic converter grid voltage phase-locking method provided in the present invention, and will not be repeated here.

[0092] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for phase locking of power electronic converter grid voltage, characterized in that: include: S1, obtain the output signal of the three-phase phase-locked loop; S2, converting the output signal of the three-phase phase-locked loop into a square wave signal; S3, judging whether the square wave signal is normal according to the preset power system stability range domain, if so, executing step S4, otherwise, executing step S5, the preset power system stability range domain includes frequency domain, period domain and phase domain; S4, output the output signal of the three-phase phase-locked loop; S5, using a sliding window to perform linear weighted calculation on the phase value of the output signal of the three-phase phase-locked loop to obtain a weighted phase value, using a sliding window to perform linear weighted calculation on the frequency value of the output signal of the three-phase phase-locked loop to obtain a weighted frequency value, and executing step S6; S6. According to the weighted phase value and the weighted frequency value, the output signal of the three-phase phase-locked loop is synthesized into an inner phase-locked signal for output and a phase-locked abnormal signal is identified.

2. The power electronic converter grid voltage phase locking method according to claim 1, characterized in that: Step S3 specifically includes: Record the period average value Tavg0 and period error range dT of the square wave signal within the preset time. Within the period range Tavg0-dT to Tavg0+dT, for the first periodic signal, determine whether the square wave signal is a normal signal based on whether the frequency of the square wave signal is between 48Hz and 51.5Hz, whether the frequency change rate does not exceed 0.2Hz / s, and whether the phase does not suddenly change. For non-first periodic signals, if the previous periodic signal is a normal signal, then compared with the previous periodic signal, the continuous periodic change is less than the preset duration, then the signal period is considered normal, and step S4 is executed; if the continuous periodic change is not less than the preset duration, then the period is considered abnormal, and step S5 is executed; if the previous periodic signal is an abnormal signal, then compared with the previous periodic signal, the continuous periodic change is less than the preset duration + dT, then the signal period is considered normal, and step S4 is executed; if the continuous periodic change is not less than the preset duration + dT, then the period is considered abnormal, and step S5 is executed, wherein the preset time covers multiple signal periods.

3. The power electronic converter grid voltage phase locking method according to claim 2, characterized in that: The default duration is 1.6us.

4. The power electronic converter grid voltage phase locking method according to claim 2, characterized in that: The default time is 30s.

5. The power electronic converter grid voltage phase locking method according to claim 4, characterized in that: Step S3 also includes: It is determined whether the cumulative time of the square wave signal judged as an abnormal signal within 10s exceeds 2s. If so, the square wave signal after the cumulative time exceeds 2s within the preset time is forcibly set as a normal signal.

6. The power electronic converter grid voltage phase locking method according to any one of claims 1 to 5, characterized in that: In step S5, the calculation formula of the weighted phase value is: in, is the weighted phase value, is the phase value of n moments arranged in reverse time order, for One-to-one corresponding phase weight value, The value decreases linearly between [0,1].

7. The method for phase locking of power electronic converter grid voltage according to any one of claims 1 to 5, characterized in that: In step S5, the calculation formula of the weighted frequency value is: in, is the weighted frequency value, is the frequency value of n moments arranged in reverse chronological order, for One-to-one corresponding frequency weight values, The value decreases linearly between [0,1].

8. A power electronic converter grid voltage phase locking device, characterized in that: include: Three-phase phase-locked loop, internal phase-locked signal building module and comprehensive judgment output module; The three-phase phase-locked loop is connected to the internal phase-locked signal construction module, and the three-phase phase-locked loop and the internal phase-locked signal construction module are respectively connected to the comprehensive judgment output module; A three-phase phase-locked loop is used to obtain a three-phase signal from a three-phase power supply, process the three-phase signal, and output a three-phase external phase-locked signal; An inner phase-locked signal construction module is used to obtain the output signal of the three-phase phase-locked loop, convert the output signal of the three-phase phase-locked loop into a square wave signal, and is also used to perform linear weighted calculation on the phase value of the output signal of the three-phase phase-locked loop using a sliding window to obtain a weighted phase value, and to perform linear weighted calculation on the frequency value of the output signal of the three-phase phase-locked loop using a sliding window to obtain a weighted frequency value, and according to the weighted phase value and the weighted frequency value, synthesize the output signal of the three-phase phase-locked loop into an inner phase-locked signal for output and identify a phase-locked abnormality signal; The comprehensive judgment output module is used to judge whether the square wave signal is normal according to the preset power system stability range domain. If so, the output signal of the three-phase phase-locked loop is output; otherwise, the inner phase-locked signal synthesized by the inner phase-locked signal construction module is output. The preset power system stability range domain includes frequency domain, period domain and phase domain.

9. The power electronic converter grid voltage phase locking device according to claim 8, characterized in that: The comprehensive judgment output module is specifically used for: Record the period average value Tavg0 and period error range dT of the square wave signal within the preset time. Within the period range Tavg0-dT to Tavg0+dT, for the first periodic signal, determine whether the square wave signal is a normal signal based on whether the frequency of the square wave signal is between 48Hz and 51.5Hz, whether the frequency change rate does not exceed 0.2Hz / s, and whether the phase does not suddenly change. For non-first periodic signals, if the previous periodic signal is a normal signal, then compared with the previous periodic signal, the continuous periodic change is less than the preset duration, then the signal period is considered normal, and step S4 is executed; if the continuous periodic change is not less than the preset duration, then the period is considered abnormal, and step S5 is executed; if the previous periodic signal is an abnormal signal, then compared with the previous periodic signal, the continuous periodic change is less than the preset duration + dT, then the signal period is considered normal, and step S4 is executed; if the continuous periodic change is not less than the preset duration + dT, then the period is considered abnormal, and step S5 is executed, wherein the preset time covers multiple signal periods.

10. A power electronic converter grid voltage phase-locking device, characterized in that: The device comprises a processor and a memory: The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the power electronic converter grid voltage phase locking method according to any one of claims 1-7 according to the instructions in the program code.

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