Generator parallel operation control method and system based on carrier synchronization

Abstract

The invention discloses a generator parallel operation control method and system based on carrier synchronization, and belongs to the technical field of power electronic conversion. A generator parallel operation control method based on carrier synchronization is characterized in that the method is applied to a system comprising a synchronous enabling unit, a synchronous signal transmitter and a plurality of parallel converters connected with the synchronous enabling unit and the synchronous signal transmitter respectively, and the method comprises the following steps: for each converter, determining a counting difference value and sending the synchronous enabling unit; the synchronous enabling unit feeds back an adjusting signal to the corresponding converter based on a comparison result of the difference value sent by the carrier wave processor of each converter and a count value threshold until the difference values sent by the carrier wave processors of all converters are smaller than the count value threshold; then, synchronous enable signals are sent to the converters respectively; and each converter drives the IGBT to realize current conversion based on the synchronous enable signal. According to the method, synchronous impact and circulation are reduced by simulating dynamic approximation of a carrier and an actual carrier.

Description

Technical Field

[0001] This application belongs to the field of power electronic converter technology, and specifically relates to a generator parallel operation control method and system based on carrier synchronization. Background Technology

[0002] In scenarios with high penetration of new energy sources, the demand for parallel operation of photovoltaic-storage synchronous generators has surged, but the circulating current problem caused by carrier asynchrony seriously restricts the system efficiency and reliability.

[0003] To address the grid-connected circulating current problem caused by carrier inconsistencies among the converter modules when multiple photovoltaic-storage synchronous generators are connected in parallel, existing converter parallel systems use CAN bus or CPLD communication for carrier synchronization. However, these methods are costly, have poor anti-interference capabilities, and are prone to synchronization failure due to signal interference. Furthermore, these synchronization methods rely on a master-slave control mode, resulting in poor module independence; a single module failure can trigger system collapse. Additionally, the rigidity of carrier phase adjustment during synchronization can easily generate inrush currents, leading to increased grid-connected circulating current and harmonic content.

[0004] In summary, existing carrier synchronization technologies mostly rely on communication buses or fixed master-slave modes, which are difficult to adapt to complex power grid environments and highly dynamic new energy power output scenarios. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a generator parallel operation control method and system based on carrier synchronization.

[0006] This application provides a generator parallel operation control method based on carrier synchronization, applied in a system including a synchronization enable unit, a synchronization signal transmitter, and multiple parallel converters connected to both. The method includes: For each converter, the operation of determining the counting difference and sending it to the synchronization enable unit is performed as follows: its analog carrier generator receives the synchronization pulse signal sent by the synchronization signal transmitter, resets the analog carrier count value to zero and starts counting again, generates an analog carrier, and sends the analog carrier count value to its carrier processor; its actual carrier generator generates an actual carrier, counts the actual carrier, and sends the actual carrier count value to its carrier processor; its carrier processor compares the actual carrier count value with the analog carrier count value, determines the counting difference, and sends it to the synchronization enable unit. Among these operations, each converter generates the same analog carrier. The synchronization enable unit feeds back adjustment signals to the corresponding converters based on the comparison between the difference sent by the carrier processors of each converter and the count value threshold, until the difference sent by the carrier processors of all converters is less than the count value threshold; then it sends a synchronization enable signal to each converter respectively. For each converter that receives the adjustment signal, its actual carrier generator and its analog carrier generator adjust the phase of the analog carrier and the actual carrier in the next cycle according to the adjustment signal; based on the phase-adjusted analog carrier and the actual carrier, the operation of determining the counting difference and sending the synchronization enable unit is performed; For each converter, upon receiving the synchronization enable signal, the enable PWM pulse generator receives the modulated wave sent by the modulated wave memory and the phase-adjusted actual carrier sent by the actual carrier generator, compares the waveforms of the two, outputs a pulse signal, and drives the IGBT to achieve conversion.

[0007] Furthermore, the synchronization enable unit, based on the comparison result between the difference sent by the carrier processor of each converter and the count value threshold, feeds back an adjustment signal to the corresponding converter, including: When the synchronization enable unit determines that the minimum absolute value of the difference among all converters is greater than the count threshold, it feeds back an adjustment signal to all converters to adjust the phase of the analog carrier and the actual carrier for the next cycle.

[0008] Furthermore, the synchronization enable unit, based on the comparison result between the difference sent by the carrier processor of each converter and the count value threshold, feeds back an adjustment signal to the corresponding converter, including: When the synchronization enable unit determines that the minimum value of the absolute value of the difference among some converters is greater than the count value threshold, it feeds back an adjustment signal to the converter whose absolute value of the difference is greater than the counter threshold to adjust the phase of the actual carrier in the next cycle.

[0009] Furthermore, the analog carrier wave is a sawtooth wave signal.

[0010] Furthermore, the generator is a photovoltaic-storage synchronous generator.

[0011] Furthermore, when the analog carrier generator cannot receive the synchronization pulse signal, it enters a standby state, and the converter operates independently without participating in grid connection; when the analog carrier generator can receive the synchronization pulse signal, the analog carrier generator restarts, generates the same analog carrier as the other analog carrier generators, and the converter re-participates in grid connection.

[0012] This application also provides a generator parallel operation control system based on carrier synchronization, including a synchronization enable unit, a synchronization signal transmitter, and multiple parallel converters connected to both. Each converter performs the following operations: determining the count difference and sending it to the synchronization enable unit; its analog carrier generator receives the synchronization pulse signal sent by the synchronization signal transmitter, resets the analog carrier count to zero and starts counting again, generates an analog carrier, and sends the analog carrier count to its carrier processor; its actual carrier generator generates an actual carrier, counts the actual carrier, and sends the actual carrier count to its carrier processor; its carrier processor compares the actual carrier count with the analog carrier count, determines the count difference, and sends it to the synchronization enable unit, wherein each converter generates the same analog carrier; and receives an adjustment signal, and its actual carrier generator and its analog carrier generator adjust the phase of the analog carrier and actual carrier for the next cycle according to the adjustment signal; based on the phase-adjusted analog carrier and actual carrier, it performs the operation of determining the count difference and sending it to the synchronization enable unit; and upon receiving the same synchronization enable signal, it enables the PWM pulse generator to receive the modulated wave sent by the modulation wave memory and the phase-adjusted actual carrier sent by the actual carrier generator, compares the waveforms of the two, outputs a pulse signal, and drives the IGBT to realize the conversion. The synchronization enable unit is used to compare the difference sent by the carrier processor of each converter with the count value threshold, and feed back the adjustment signal to the corresponding converter until the difference sent by the carrier processor of all converters is less than the count value threshold; then, it sends a synchronization enable signal to each converter respectively.

[0013] Furthermore, the synchronization enable unit is specifically used to determine that when the minimum value among the absolute values ​​of the differences of all converters is greater than the count value threshold, it feeds back an adjustment signal to all converters to adjust the phase of the analog carrier and the actual carrier in the next cycle.

[0014] Furthermore, the synchronization enable unit is specifically used to determine that when the minimum value of the absolute value of the difference among some converters is greater than the count value threshold, it feeds back an adjustment signal to the converter whose absolute value of the difference is greater than the counter threshold to adjust the phase of the actual carrier in the next cycle.

[0015] Furthermore, the generator is a photovoltaic-storage synchronous generator.

[0016] Compared with the prior art, this application has the following advantages: The solution presented in this application provides a flexible carrier synchronization mechanism that reduces synchronization impact and circulating current by dynamically approximating the simulated carrier with the actual carrier. It is designed as a masterless distributed control architecture, enhancing the system's modular scalability and anti-interference capabilities; and it implements an automatic synchronization signal recovery function, ensuring that the abnormal exit / entry of a single module does not affect the overall system operation.

[0017] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart illustrating a carrier synchronization process according to an embodiment of this application is shown; Figure 2 A schematic diagram of the structure of a carrier synchronization system according to an embodiment of this application is shown; Figure 3 A schematic diagram of actual carrier conversion according to an embodiment of this application is shown; Figure 4 A schematic diagram of phase adjustment when the actual carrier phase leads the simulated carrier phase according to an embodiment of this application is shown; Figure 5 A schematic diagram of phase adjustment when the actual carrier phase lags behind the simulated carrier according to an embodiment of this application is shown. Figure 6 A diagram illustrating the synchronization harmonics effect without carrier synchronization according to an embodiment of this application is shown. Figure 7 A diagram illustrating the synchronous harmonic effect when using the method of this application according to an embodiment of this application is shown. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] like Figure 1 As shown, it is a system overall architecture diagram of an embodiment of this application, including: a synchronization enable unit ( Figure 1(Not shown in the diagram) Synchronization signal transmitter, analog carrier generator, actual carrier generator, carrier processor, PWM pulse generator, and modulation wave storage, wherein the synchronization signal transmitter is connected to the analog carrier generator; one end of the carrier processor is connected to the analog carrier generator, and the other end is connected to the actual carrier generator; the PWM pulse generator is connected to the actual carrier generator and the modulation wave storage. Synchronization signal transmitter, used to send synchronization pulse signals The analog carrier generator is used to receive synchronization pulse signals and generate analog carriers, and to receive signals from the carrier processor to readjust the analog carriers; The actual carrier generator is used to send the actual carrier to the carrier processor, receive signals from the carrier processor to readjust the actual carrier, and send the actual carrier to the PWM pulse generator. A carrier processor is used to compare an analog carrier with an actual carrier and calculate their phase deviation. The synchronization enable unit is used to receive the phase deviation sent by each carrier processor and adjust the signal based on the deviation feedback.

[0022] A PWM pulse generator is used to compare the actual carrier wave with the modulated wave to generate IGBT signals; Modulation wave storage is used to send modulation waves to the PWM pulse generator.

[0023] This invention provides a carrier synchronization control method for parallel operation of synchronous generators. Specifically, the generator can be a photoelectric-storage synchronous generator, such as... Figure 2 As shown, it includes the following steps: S1: For each converter, perform the operation of determining the count difference and sending the synchronization enable unit, as follows: S11: Its analog carrier generator receives the synchronization pulse signal sent by the synchronization signal transmitter, resets the analog carrier count value to zero and starts counting again, generates an analog carrier, and sends the analog carrier count value to its carrier processor. S12: The actual carrier generator generates an actual carrier, counts the actual carrier, and sends the actual carrier count value to its carrier processor; its carrier processor compares the actual carrier count value with the analog carrier count value, determines the count difference, and sends it to the synchronization enable unit. Among them, each converter generates the same analog carrier. S2: The synchronization enable unit determines whether the absolute value of the difference sent by the carrier processor of each converter is less than the count value threshold. If not, proceed to step S3; if yes, proceed to step S5. S3: The synchronization enable unit feeds back an adjustment signal to the converter whose difference is greater than or equal to the count value threshold, and then executes S4; S4: For each converter that receives the adjustment signal, its actual carrier generator and its analog carrier generator adjust the phase of the analog carrier and the actual carrier for the next cycle according to the adjustment signal; then S1 is executed. S5: Send a synchronization enable signal to each converter respectively, and then execute S6; S6: For each converter, upon receiving the synchronous enable signal, the PWM pulse generator is enabled to receive the modulated wave sent by the modulated wave memory and the phase-adjusted actual carrier sent by the actual carrier generator. The waveforms of the two are compared to output a pulse signal to drive the IGBT to achieve conversion.

[0024] In step S4, when the actual carrier phases of all converters are consistent, each converter performs PWM modulation to generate AC power and connects it to the AC bus to drive the IGBT to achieve conversion.

[0025] It should be noted that the above actual carrier count and analog carrier count values ​​are per-unit values, corresponding to the phase quantization index of the carrier signal within the PWM control cycle.

[0026] The following explains the specific implementation of the synchronization enable unit in S2, which feeds back adjustment signals to the corresponding converters based on the comparison results between the difference sent by the carrier processors of each converter and the count threshold: When the minimum absolute value of the difference between all converters is greater than the count threshold, the synchronization enable unit feeds back an adjustment signal to all converters to adjust the phase of the analog carrier and the actual carrier for the next cycle.

[0027] When the minimum value among the absolute values ​​of the differences between some converters is greater than the count threshold, the synchronization enable unit feeds back an adjustment signal to the converter whose absolute value of the difference is greater than the counter threshold to adjust the phase of the actual carrier in the next cycle.

[0028] Specifically, the analog carrier wave is a sawtooth wave signal, or it can be a triangular wave signal.

[0029] Furthermore, the specific adjustments are as follows: Assume the peak value of the simulated carrier is A0, the phase is φ0, and the current count value is u0; the peak value of the actual carrier of the first converter is 0.5A1, the phase is φ1, and the current count value is u. 10 The peak value of the actual carrier wave of the nth converter is 0.5A. n The phase is φ n The current count value is u n0 The count threshold is φ, and the phase adjustment step size is... .

[0030] To facilitate comparison of the count values ​​of the actual carrier and the analog carrier, the triangular waveform of the actual carrier is first converted into a sawtooth waveform. For example... Figure 3 As shown, after conversion, the peak value of the actual carrier of the first converter is A1, and the phase is φ1. When the actual carrier is in the count value increasing segment, the current count value u1 = u 10 When the actual carrier is in the count value decreasing segment, the current count value u1 = A1 - u 10 The peak value of the actual carrier wave of the nth converter after conversion is A. n The phase is φ n When the actual carrier is in the count value increasing phase, the current count value u n =u n0 When the actual carrier is in the count value decreasing segment, the current count value u n =A n -u n0 .

[0031] Calculate the difference G1(n) between the count values ​​of each actual carrier and the analog carrier:

[0032] Calculate the minimum absolute value of the deviation between the count values ​​of the actual carrier and the analog carrier, G2(m):

[0033] If G2(m) > φ, then the phase of the analog carrier and the actual carrier in the next cycle needs to be adjusted. The specific adjustment of the phase of the analog carrier and the actual carrier in the next cycle is as follows: Phase of analog carrier:

[0034] Phase of the actual carrier:

[0035] in, This indicates the phase of the analog carrier after the first round of adjustment. This represents the phase of the actual carrier after the first round of adjustment for the nth converter. It should be noted that in the above formula, n represents any converter, because the phase of the actual carrier of each converter needs to be adjusted.

[0036] If G2(m) < φ, it means that the actual carrier and the analog carrier of the m-th converter are in phase, and their values ​​are fixed and no further adjustment is needed. Calculate the minimum value G2(o) of the count deviation between the actual carrier and the analog carrier of the remaining converters:

[0037] If G2(o)>φ, then the phase of the next cycle of the actual carrier of each remaining converter needs to be adjusted.

[0038] Phase of the actual carrier:

[0039] in, This represents the phase of the actual carrier of the nth remaining converter after the second round of adjustment. Here, n represents any remaining converter, because the phase of the actual carrier of each remaining converter needs to be adjusted.

[0040] If G2(o) < φ, it means that the actual carrier and the analog carrier of the o-th converter are in phase. The phase of the actual carrier of the o-th converter is fixed and no further adjustment is made. Continue to calculate the minimum value of the count value deviation between the actual carrier and the analog carrier of the remaining converters until the phase of all converters meets the requirements.

[0041] Figure 4 This diagram illustrates phase adjustment when the actual carrier phase leads the simulated carrier phase. Figure 5 This diagram illustrates phase adjustment when the actual carrier phase lags behind the simulated carrier phase. Figure 4 and Figure 5 After two adjustments, the actual carrier phase and the simulated carrier phase are consistent. Figure 4 and Figure 5 middle This represents the actual carrier count value after the first adjustment. This represents the actual carrier count value after the second adjustment; This represents the analog carrier count value after the first adjustment. This represents the analog carrier count value after the second adjustment.

[0042] Furthermore, when the analog carrier generator cannot receive the synchronization pulse signal, it enters a standby state, and the converter operates independently without participating in grid connection; when the analog carrier generator can receive the synchronization pulse signal, the analog carrier generator restarts, generates the same analog carrier as the other analog carrier generators, and the converter re-participates in grid connection.

[0043] Based on the above method, this application also provides a generator parallel operation control system based on carrier synchronization, including a synchronization enable unit, a synchronization signal transmitter, and multiple parallel converters connected to both; each converter includes a modulation wave memory, an analog carrier generator, a carrier processor, an actual carrier generator, and a PWM pulse generator connected in series, wherein the modulation wave memory is connected to the PWM pulse generator; Each converter performs the following operations: determining the count difference and sending it to the synchronization enable unit; its analog carrier generator receives the synchronization pulse signal sent by the synchronization signal transmitter, resets the analog carrier count to zero and starts counting again, generates an analog carrier, and sends the analog carrier count to its carrier processor; its actual carrier generator generates an actual carrier, counts the actual carrier, and sends the actual carrier count to its carrier processor; its carrier processor compares the actual carrier count with the analog carrier count, determines the count difference, and sends it to the synchronization enable unit, wherein each converter generates the same analog carrier; and receives an adjustment signal, and its actual carrier generator and its analog carrier generator adjust the phase of the analog carrier and actual carrier for the next cycle according to the adjustment signal; based on the phase-adjusted analog carrier and actual carrier, it performs the operation of determining the count difference and sending it to the synchronization enable unit; and upon receiving the same synchronization enable signal, it enables the PWM pulse generator to receive the modulated wave sent by the modulation wave memory and the phase-adjusted actual carrier sent by the actual carrier generator, compares the waveforms of the two, outputs a pulse signal, and drives the IGBT to realize the conversion. The synchronization enable unit is used to compare the difference sent by the carrier processor of each converter with the count value threshold, and feed back the adjustment signal to the corresponding converter until the difference sent by the carrier processor of all converters is less than the count value threshold; then, it sends a synchronization enable signal to each converter respectively.

[0044] Furthermore, the synchronization enable unit is specifically used to determine that when the minimum value among the absolute values ​​of the differences of all converters is greater than the count value threshold, it feeds back an adjustment signal to all converters to adjust the phase of the analog carrier and the actual carrier in the next cycle.

[0045] Furthermore, the synchronization enable unit is specifically used to determine that when the minimum value of the absolute value of the difference among some converters is greater than the count value threshold, it feeds back an adjustment signal to the converter whose absolute value of the difference is greater than the counter threshold to adjust the phase of the next cycle of the actual carrier.

[0046] The carrier synchronization control method provided in this application embodiment involves each converter receiving a synchronization pulse signal to form a synchronous analog carrier. The actual carrier and the analog carrier are dynamically approximated, and their respective carriers are adjusted for flexible synchronization. This results in a frequency modulation accuracy Δf < 0.01Hz for multi-machine off-grid operation, which is superior to other methods where Δf > 0.05Hz. At the same time, the flexible, shockless synchronization between the actual carrier and the analog carrier enhances the system's anti-interference capability and effectively suppresses circulating currents and harmonics in wide-area parallel operation of grid-type optical-storage systems. Figure 6 and Figure 7The diagrams show the synchronization harmonic effects without carrier synchronization and with the method of this application, respectively. In the diagrams, curves 2 and 3 represent the voltages of the AC phase A reactors of the two PCS units, and curve 4 represents the voltage difference between the AC phase A reactors of the two PCS units. Ideally, the voltage curves of the two reactors should completely overlap, and the harmonic content should be low. In reality, there is a phase deviation between the voltages of the two reactors, and the harmonics are relatively large. After using carrier synchronization, the phase difference and harmonics of the voltages of the two reactors are significantly reduced, indicating that the current and harmonics between the two devices are significantly reduced. This method has a significant circulating harmonic suppression effect.

[0047] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A generator parallel operation control method based on carrier synchronization, characterized in that, In a system comprising a synchronization enable unit, a synchronization signal transmitter, and multiple parallel converters connected to both, the method includes: For each converter, the operation of determining the counting difference and sending it to the synchronization enable unit is performed as follows: its analog carrier generator receives the synchronization pulse signal sent by the synchronization signal transmitter, resets the analog carrier count value to zero and starts counting again, generates an analog carrier, and sends the analog carrier count value to its carrier processor; its actual carrier generator generates an actual carrier, counts the actual carrier, and sends the actual carrier count value to its carrier processor; its carrier processor compares the actual carrier count value with the analog carrier count value, determines the counting difference, and sends it to the synchronization enable unit. Among these operations, each converter generates the same analog carrier. The synchronization enable unit feeds back adjustment signals to the corresponding converters based on the comparison between the difference sent by the carrier processors of each converter and the count value threshold, until the difference sent by the carrier processors of all converters is less than the count value threshold; then it sends a synchronization enable signal to each converter respectively. For each converter that receives the adjustment signal, its actual carrier generator and its analog carrier generator adjust the phase of the analog carrier and the actual carrier in the next cycle according to the adjustment signal; based on the phase-adjusted analog carrier and the actual carrier, the operation of determining the counting difference and sending the synchronization enable unit is performed; For each converter, upon receiving the synchronization enable signal, the enable PWM pulse generator receives the modulated wave sent by the modulated wave memory and the phase-adjusted actual carrier sent by the actual carrier generator, compares the waveforms of the two, outputs a pulse signal, and drives the IGBT to achieve conversion.

2. The method according to claim 1, characterized in that, The synchronization enable unit, based on the comparison result between the difference sent by the carrier processor of each converter and the count value threshold, feeds back adjustment signals to the corresponding converter, including: The synchronization enable unit determines that the minimum absolute value of the difference among all converters is greater than the count threshold, and feeds back an adjustment signal to all converters to adjust the phase of the analog carrier and the actual carrier for the next cycle.

3. The method according to claim 1, characterized in that, The synchronization enable unit, based on the comparison result between the difference sent by the carrier processor of each converter and the count value threshold, feeds back adjustment signals to the corresponding converter, including: The synchronization enable unit determines that the minimum absolute value of the difference among some converters is greater than the count threshold, and feeds back an adjustment signal to the converter whose absolute value of the difference is greater than the counter threshold to adjust the phase of the actual carrier in the next cycle.

4. The method according to any one of claims 1-3, characterized in that, The analog carrier wave is a sawtooth wave signal.

5. The method according to any one of claims 1-3, characterized in that, The generator is a photovoltaic-storage synchronous generator.

6. The method according to claim 1, characterized in that, When the analog carrier generator cannot receive the synchronization pulse signal, it enters standby mode and the converter operates independently without participating in grid connection. When the analog carrier generator can receive the synchronization pulse signal, it restarts and generates the same analog carrier as the other analog carrier generators, and the converter rejoins grid connection.

7. A generator parallel operation control system based on carrier synchronization, characterized in that, It includes a synchronization enable unit, a synchronization signal transmitter, and multiple parallel converters connected to both. Each converter performs the operation of determining the count difference and sending the synchronization enable unit: its analog carrier generator receives the synchronization pulse signal sent by the synchronization signal transmitter, resets the analog carrier count value to zero and starts counting again, generates an analog carrier, and sends the analog carrier count value to its carrier processor. Its actual carrier generator generates actual carriers, counts the actual carriers, and sends the actual carrier count value to its carrier processor; Its carrier processor compares the actual carrier count value with the analog carrier count value, determines the count difference, and sends it to the synchronization enable unit. Each converter generates the same analog carrier. It also receives an adjustment signal, and its actual carrier generator and its analog carrier generator adjust the phase of the analog carrier and actual carrier for the next cycle according to the adjustment signal. Based on the phase-adjusted analog carrier and actual carrier, it performs the operation of determining the count difference and sending it to the synchronization enable unit. Furthermore, upon receiving the synchronization enable signal, it enables the PWM pulse generator to receive the modulated wave sent by the modulation wave memory and the phase-adjusted actual carrier sent by the actual carrier generator, compares the waveforms of the two, and outputs a pulse signal to drive the IGBT to achieve current conversion. The synchronization enable unit is used to compare the difference sent by the carrier processor of each converter with the count value threshold, and feed back the adjustment signal to the corresponding converter until the difference sent by the carrier processor of all converters is less than the count value threshold; then, it sends a synchronization enable signal to each converter respectively.

8. The system according to claim 7, characterized in that, The synchronization enable unit is specifically used to determine that when the minimum value among the absolute values ​​of the differences of all converters is greater than the count value threshold, it feeds back an adjustment signal to all converters to adjust the phase of the analog carrier and the actual carrier for the next cycle.

9. The system according to claim 7, characterized in that, The synchronization enable unit is specifically used to determine that when the minimum value of the absolute value of the difference among some converters is greater than the count value threshold, it feeds back an adjustment signal to the converter whose absolute value of the difference is greater than the counter threshold to adjust the phase of the actual carrier in the next cycle.

10. The system according to any one of claims 7-9, characterized in that, The generator is a photovoltaic-storage synchronous generator.

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