Cooperative method and system under unreliable communication and related distributed micro inverter

Abstract

The invention discloses a coordination method and system under unreliable communication and a related distributed micro inverter, relates to the field of new energy power generation, and is used for realizing reliable coordination of alternating current output voltage, frequency and phase of a large-scale distributed micro inverter in an unreliable wireless communication environment. According to the invention, a distributed micro inverter architecture is adopted, a control center broadcasts a synchronizing signal, the micro inverter receiving the synchronizing signal executes synchronization according to signal indication, if the synchronizing signal is not received, the micro inverter follows the phase of the alternating current bus for synchronization, and if the phase of the alternating current bus is not detected, the output is cut off. According to the invention, reliable cooperation of parallel output AC voltage, frequency and phase of a large-scale and large-range distributed micro inverter under an unreliable communication condition is supported.

Description

Technical Field

[0001] The present invention relates to the field of new energy, and in particular to a coordination method and system for large-scale distributed micro-inverters under unreliable communication, and a distributed micro-inverter supporting synchronization under unreliable communication. Background Art

[0002] Renewable energy generation units (such as photovoltaic power generation or wind power generation) usually generate direct current, which needs to be converted into alternating current through an inverter before it can be connected to the grid (partial networking or integration into the grid). At present, most new energy power stations connect a large number of new energy generation units in series and output them to the grid or load through a centralized inverter with a high-power inverter. This networking method has low safety and reliability. The high-power inverter is in a high-temperature and high-load state for a long time, which is prone to fire. In addition, once a new energy generation unit fails, the entire line will be affected.

[0003] In view of the risks of centralized inverters, it is considered to use distributed micro-inverters to invert one or a small number of new energy power generation units respectively, and then output them in parallel. The power of each distributed micro-inverter is usually small, between 500W and 5000W. For power stations, it is usually necessary to connect a large number of distributed micro-inverters in parallel to provide a large power.

[0004] The frequency and phase of the AC power output by each distributed micro-inverter have a significant impact on the power and performance of large-scale parallel output. The frequency and phase deviation between multiple micro-inverters will cause local circulation, seriously affecting the quality of the output AC power, affecting the normal operation of the power grid, increasing power grid consumption and possibly damaging other loads or other substation facilities connected to the power grid. Therefore, it is necessary to synchronize the voltage, frequency and phase of all micro-inverters connected to the grid.

[0005] Large-scale (e.g., more than 100) distributed micro-inverters can coordinate output frequency and voltage and current phases through wired or wireless communication. Wired communication requires a large amount of wiring, especially for distributed micro-inverter scenarios. The amount of wiring is quite large, the cost is high, and the reliability is low. It is also prone to line failure when used outdoors, causing the micro-inverter to lose synchronization control. The wireless communication method needs to rely on a reliable wireless communication network, which is feasible for micro-inverters deployed in a small area, but for large-scale or large-scale distributed micro-inverters, such as large photovoltaic stations, thousands of micro-inverters need to be deployed within a few square kilometers. This makes the wireless communication network no longer reliable, and it is impossible to guarantee that all distributed micro-inverters can have a reliable wireless communication network to obtain synchronization signals at all times. When multiple micro-inverters cannot synchronize frequency and phase according to the synchronization signal, local circulation and other situations that affect the quality of the output AC power will occur, affecting the reliability of the AC output of large-scale distributed micro-inverters. Summary of the invention

[0006] The object of the present invention is to provide a coordination method, system and related distributed micro-inverters under unreliable communication to address the above-mentioned problems, so as to achieve reliable coordination of AC output voltage, frequency and phase of large-scale distributed micro-inverters under unreliable wireless communication environment.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A large-scale distributed micro-inverter coordination method under unreliable communication, wherein each distributed micro-inverter is respectively connected to at least one new energy power generation unit, each distributed micro-inverter is respectively connected to a control center by wireless communication, and the AC output of each distributed micro-inverter is connected in parallel to an AC bus; the coordination method comprises:

[0009] Each distributed micro-inverter respectively monitors the synchronization signal broadcast by the control center;

[0010] The distributed micro-inverter receiving the synchronization signal synchronizes the output voltage, phase and frequency according to the instruction of the synchronization signal;

[0011] The distributed micro-inverters that have not received the synchronization signal are synchronized with reference to the phase on the AC bus;

[0012] The distributed micro-inverter that has not received the synchronization signal and has failed to detect the phase on the AC bus cuts off output.

[0013] Furthermore, the method also includes:

[0014] The distributed micro-inverter that receives the first control instruction sent separately by the control center synchronizes the output voltage, phase and frequency according to the instruction of the first control instruction, or synchronizes with reference to the phase on the AC bus, or cuts off the output.

[0015] Furthermore, the method also includes:

[0016] The distributed micro-inverter that has not received the synchronization signal continues to monitor the synchronization signal, and after receiving the synchronization signal, synchronizes the output voltage, phase and frequency according to the instruction of the synchronization signal.

[0017] Furthermore, the synchronization signal is generated by the control center by comparing the voltage, frequency and phase indicated by the synchronization requirement with the voltage, frequency and phase monitored at the public grid access point.

[0018] Furthermore, the synchronization signal is generated by the control center under the adopted synchronization clock.

[0019] Furthermore, the synchronization signal is broadcast periodically by the control center.

[0020] A large-scale distributed micro-inverter coordination system under unreliable communication, each distributed micro-inverter is respectively connected to at least one new energy power generation unit, each distributed micro-inverter is respectively connected to a control center by wireless communication, and the AC output of each distributed micro-inverter is connected in parallel to the AC bus;

[0021] The control center is used to broadcast synchronization signals;

[0022] Each of the distributed micro-inverters continuously monitors the synchronization signal broadcast by the control center; in response to receiving the synchronization signal, synchronizes the output voltage, phase and frequency according to the instructions of the synchronization signal; in response to not receiving the synchronization signal, synchronizes with reference to the phase on the AC bus; in response to not receiving the synchronization signal and failing to detect the phase on the AC bus, cuts off the output.

[0023] A distributed micro-inverter supporting synchronization under unreliable communication, wherein the distributed micro-inverter is connected to at least one new energy power generation unit, the distributed micro-inverter is wirelessly connected to a control center, and the AC output of the distributed micro-inverter is connected in parallel to an AC bus; the distributed micro-inverter is configured as follows:

[0024] Continuously monitoring the synchronization signal broadcast by the control center;

[0025] In response to receiving the synchronization signal, synchronizing the output voltage, phase and frequency according to the instruction of the synchronization signal;

[0026] In response to not receiving the synchronization signal, performing synchronization with reference to a phase on the AC bus;

[0027] In response to not receiving the synchronization signal and failing to detect the phase on the AC bus, the output is cut off.

[0028] Furthermore, the distributed micro-inverter is further configured as:

[0029] Continuously monitoring the first control instruction sent separately by the control center;

[0030] In response to receiving the first control instruction, the output voltage, phase and frequency are synchronized according to the instruction of the first control instruction, or the phase on the AC bus is referenced for synchronization, or the output is cut off.

[0031] Furthermore, the distributed micro-inverter is further configured as:

[0032] After each synchronization, the output frequency is maintained based on the internal local reference clock.

[0033] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0034] The present invention uses distributed micro-inverters to invert and output the weak direct current of each / group of new energy power generation units, avoiding the potential risks of centralized inversion. The present invention uses wireless communication control and the control of the distributed micro-inverter itself, so that the micro-inverter that receives the synchronization signal is synchronized according to the synchronization signal instruction. When it cannot be synchronized according to the synchronization signal due to poor quality of the wireless communication network or other control instructions of the control center, it automatically follows the phase of the AC bus for synchronization. If no signal or instruction is received and the phase of the AC bus is not detected, the output is cut off to avoid negative impact on the parallel AC power on the AC bus, and reliable coordination of voltage, frequency and phase between large-scale and large-scale distributed micro-inverters in an unreliable communication environment is achieved, ensuring that even under unreliable wireless communication network conditions, the high power and high reliability of the parallel output of AC power by large-scale distributed micro-inverters are still maintained. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0036] Figure 1 It is a structural diagram of a large-scale distributed micro-inverter cooperation system in one embodiment.

[0037] Figure 2 A timing diagram of the operation of a coordinated system of distributed micro-inverters under unreliable communication in one embodiment.

[0038] In the figure, 100 is a distributed micro inverter, 101 is a control center, and 102 is a power quality measurement device for a power grid. DETAILED DESCRIPTION

[0039] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0040] Any feature disclosed in this specification (including any additional claims and abstract), unless otherwise stated, may be replaced by other equivalent or alternative features having similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0041] Renewable energy power plants (such as photovoltaic power plants or wind power plants) can be roughly divided into two deployment forms. One is an independent networking form, that is, the electricity generated by all renewable energy power generation units (such as photovoltaic panels or wind turbines) in the site is not connected to the power grid, but is directly supplied to specific loads after being inverted by the inverter, or stored in energy storage units. The other is a grid-connected networking mode, that is, the electricity generated by all renewable energy power generation units is inverted by the inverter and then connected to the power grid. Regardless of the method, the inverter link is involved.

[0042] At present, the conventional design of renewable energy power plants is to connect the direct current generated by a large number of renewable energy power generation units in series, use a small number of high-power inverters for centralized inversion processing, and convert it into alternating current for transmission. This method generates a lot of heat from the inverter, which requires high-power heat dissipation, otherwise it is easy to damage the equipment and cause a fire. On the one hand, the heat dissipation link requires separate cost considerations, and on the other hand, it will consume a lot of electricity and reduce the external power generation of the power station. In addition, if a renewable energy power generation unit fails, all renewable energy power generation units on the link where it is located will not work properly, and the reliability of power generation is low.

[0043] In this regard, according to the embodiment of the present application, a distributed micro-inverter solution is designed, that is, a distributed micro-inverter 100 is connected to each or a small number of several new energy power generation units to form a layout architecture of the distributed micro-inverter 100, and then the AC output of each distributed micro-inverter 100 is connected in parallel to the AC bus, which may be a single-phase two-wire AC bus, or a three-phase three-wire bus, or a three-phase four-wire AC bus. In this way, although the output power of each distributed micro-inverter 100 is not high, it can also output high-power AC power when connected in parallel and synchronized in frequency and phase. Moreover, since the output power of each distributed micro-inverter 100 is not high, it does not need to be equipped with heat dissipation facilities separately, and natural heat dissipation is sufficient, which saves the system construction cost and also saves the power consumption of the power plant. Under this system structure, even if a new energy power generation unit fails, it only affects itself or a small number of new energy power generation units around it, and has little effect on the overall power generation of the plant, thereby improving the safety and reliability of the power plant.

[0044] However, the design of the distributed micro-inverter 100 architecture greatly increases the number of inverters in the power plant. The AC outputs of all distributed micro-inverters 100 are connected in parallel to the AC busbar. It is necessary to ensure the synchronization between the AC output frequency, voltage, and current phase of each distributed micro-inverter 100 to avoid the occurrence of local circulation phenomena, so as to ensure the reliable coordination of the AC output of large-scale distributed micro-inverters 100. Therefore, in some embodiments, the synchronization of the output voltage, frequency, and phase of each distributed micro-inverter 100 is controlled by a centralized control method.

[0045] Considering the huge number of distributed micro-inverters 100, if wired communication is used for collaborative control, the number and complexity of wiring required are too high, which is not ideal in terms of cost and reliability. Therefore, in some embodiments, wireless communication is used to collaboratively control large-scale distributed micro-inverters 100 in a power plant station, and all distributed micro-inverters 100 are wirelessly connected to the control center 101, such as Figure 1 For example, in some specific implementations, each distributed micro-inverter 100 is respectively installed with an Internet of Things communication module, such as a communication module supporting protocols such as WIoTa, NB-IoT or LORA, and the Internet of Things communication module is connected to the inverter circuit in the micro-inverter.

[0046] Example 1

[0047] refer to Figure 2 In some embodiments, a method for coordinating large-scale distributed micro-inverters 100 under unreliable communication includes:

[0048] 1) Each distributed micro-inverter 100 monitors the synchronization signal broadcast by the control center 101 respectively.

[0049] The control center 101 may be one or more, each of which is responsible for coordinated control within a certain area. In some embodiments, in order to ensure that the power plant can maintain strict coordination for a long time, the control center 101 is configured to regularly broadcast synchronization signals to regularly trigger each distributed micro-inverter 100 to synchronize voltage, frequency and phase.

[0050] The synchronization signal carries information indicating the AC output voltage (such as the target voltage), frequency, and phase (one phase for single-phase AC power and three phases with a phase difference of 120 degrees for three-phase AC power). Therefore, the synchronization signal needs to be generated according to actual needs, and some or all of this information in the synchronization signal sent by the control center 101 each time may be different.

[0051] In some embodiments, a power grid power quality measuring device 102 is provided at the public grid access point on the AC bus, which is a mature and purchasable facility, and no additional modification is performed here. The control center 101 is connected to the power grid power quality measuring device 102 to obtain the voltage, frequency and phase information of the AC power on the current AC bus. The control center 101 compares the voltage, frequency and phase indicated by the synchronization requirement with the voltage, frequency and phase of the public grid access point obtained from the power grid power quality measuring device 102, and determines the coordination requirements for each distributed micro-inverter 100 according to the comparison results, that is, the synchronization requirements of voltage, frequency and phase, and generates corresponding synchronization signals. The so-called synchronization requirements can be the requirements for voltage, frequency and phase under the grid-type conditions, or the requirements for voltage, frequency and phase of the grid-connected AC power under the weak grid condition.

[0052] In some embodiments, a local precise synchronization clock is configured in the control center 101, and the synchronization signal generated by the control center 101 is generated with reference to the period of the local precise synchronization clock. In addition, the control center 101 can also generate a synchronization signal by giving the period of the GPS or Beidou satellite reference clock.

[0053] Since the synchronization signal is broadcast through a wireless communication network, the synchronization signal can be in the form of an analog signal or a digital signal:

[0054] A. Analog signal: The analog signal is obtained by modulating a sinusoidal wave signal for voltage, frequency and phase synchronization on a predetermined analog carrier using amplitude modulation, phase modulation or frequency modulation.

[0055] B. Digital signal: This digital signal is obtained by periodically / non-periodically transmitting a digital phase reference on a predetermined digital channel. The digital phase reference uses the timing information used to synchronize the phases of voltage and current as a reference. The digital signal carries digital information used to synchronize the phases of voltage and current. In addition, the digital phase reference can also be spread spectrum, frequency modulated, scrambled, encrypted, etc. in a digital manner to prevent external attacks.

[0056] 2) Each distributed micro-inverter 100 monitors the synchronization signal broadcast by the control center 101 respectively.

[0057] In some embodiments, in order to obtain the synchronization signal in time, each distributed micro inverter 100 continuously monitors the synchronization signal of the control center 101 .

[0058] 3) Response to synchronization signal.

[0059] There are two results of monitoring the synchronization signal. One is that the synchronization signal is received after the control center 101 broadcasts the synchronization signal. The other is that the synchronization signal is not successfully received after the control center 101 broadcasts the synchronization signal due to the unreliability of the wireless communication network (such as congestion, delay, interference, etc.).

[0060] A. The distributed micro-inverter 100 that receives the synchronization signal synchronizes the output voltage, phase and frequency according to the instruction of the synchronization signal; such distributed micro-inverter 100 can be called a grid-type micro-inverter.

[0061] B. The distributed micro-inverter 100 that has not received the synchronization signal is synchronized with reference to the phase on the AC bus. This type of distributed micro-inverter 100 can be called a grid-following micro-inverter.

[0062] C. The distributed micro-inverter 100 that has not received the synchronization signal and failed to detect the phase on the AC bus cuts off output.

[0063] Although the distributed micro-inverter 100 that has not received the synchronization signal follows the phase on the AC bus for synchronization or cuts off the output, it still continues to monitor the synchronization signal broadcast by the control center 101 on the wireless channel. Once the synchronization signal is received, the output voltage, phase and frequency are synchronized according to the instructions of the synchronization signal.

[0064] In a power plant, the number of distributed micro-inverters 100 connected in parallel on the AC bus is relatively large. Through the above design, when only a small number of distributed micro-inverters 100 fail to become meshed micro-inverters due to the instability of the wireless communication network or other reasons, they can still ensure the synchronization with the AC wiring phase as much as possible, and actively cut off the output when the reference phase is lost to avoid negative impact on the AC bus output performance.

[0065] Since the synchronization signal is broadcast periodically rather than sent in real time, and the synchronization signal may not be received due to an unreliable communication network, it is possible to consider maintaining the stability of the AC output frequency during the period between adjacent synchronization signals for the distributed micro-inverter 100. To this end, in some embodiments, each distributed micro-inverter 100 is configured with a local reference clock, such as a crystal reference clock with an accuracy of 10ppm, which can maintain the output AC frequency deviation within 1% of the 50Hz / 60Hz power frequency in a short period of time (such as 500 seconds).

[0066] In addition, for different collaborative goals, it may not be required that all distributed micro-inverters 100 synchronize voltage, frequency and phase according to the same standard. For example, if the power generation power of some new energy power generation units is relatively low, the corresponding distributed micro-inverter 100 is not required to output the same voltage target value as other distributed micro-inverters 100. In this regard, the control center 101 is also configured to send a first control instruction to a specific (target) distributed micro-inverter 100 regularly or irregularly. The sending method can be unicast, multicast or groupcast, which is determined according to actual needs. The first control instruction carries information about the AC output voltage, frequency and (voltage, current) phase. In addition, the first control instruction may also directly instruct the target distributed micro-inverter 100 unit to synchronize with the phase on the AC bus, or cut off the output. A description is required. The first control instruction here is a general term for other signals that are different from the broadcast synchronization signal. In the specific implementation, the corresponding first control instruction can be configured as a control signal carrying different instruction commands, depending on whether it is to instruct the target distributed micro-inverter 100 to synchronize voltage, frequency and phase, or to instruct the target distributed micro-inverter 100 to follow the phase of the AC bus, or to instruct the target distributed micro-inverter to cut off the output.

[0067] On this basis, the control center 101 can also generate a first control instruction for one or some distributed micro-inverter 100 units separately to put forward corresponding voltage, frequency and phase requirements for this / these distributed micro-inverters 100, or directly require these distributed micro-inverters 100 to synchronize with the phase on the AC bus, or directly require these distributed micro-inverters 100 to cut off the output.

[0068] Example 2

[0069] This embodiment introduces a large-scale distributed micro-inverter 100 cooperative system under unreliable communication. Figure 1 The collaborative system includes a control center 101 and a large number of distributed micro-inverters 100. Each distributed micro-inverter 100 is connected to one or a small number of more new energy power generation units, each distributed micro-inverter 100 is wirelessly connected to the control center 101, and the AC output of each distributed micro-inverter 100 is connected in parallel to the AC bus.

[0070] See attached Figure 2 , each distributed micro inverter 100 continuously monitors the synchronization signal broadcast by the control center 101. In response to receiving the synchronization signal, the output voltage, phase and frequency are synchronized according to the instruction of the synchronization signal; in response to not receiving the synchronization signal, synchronization is performed with reference to the phase on the AC bus; in response to not receiving the synchronization signal and failing to detect the phase on the AC bus, the output is cut off.

[0071] In addition, the control center 101 also sends a first control instruction separately to the target distributed micro-inverter 100. The distributed micro-inverter 100 that receives the first control instruction separately sent by the control center 101 synchronizes the output voltage, phase and frequency according to the instructions of the first control instruction, or synchronizes with reference to the phase on the AC bus, or cuts off the output.

[0072] Since each distributed micro-inverter 100 continuously monitors the synchronization signal broadcast by the control center 101, if it follows the phase of the AC bus or cuts off the output due to failure to receive the synchronization signal within a broadcast time slot, once it receives the broadcast synchronization signal in the subsequent time, it will immediately synchronize the output voltage, phase and frequency according to the instructions of the synchronization signal.

[0073] Regarding the generation and broadcast cycle of the synchronization signal, or the relevant limitations of the first control instruction, the distributed micro-inverter 100, etc., please refer to the corresponding content in Example 1, and no further details will be given here.

[0074] Example 3

[0075] This embodiment separately introduces a distributed micro-inverter 100 that supports synchronization under unreliable communication. Similar to the above embodiment, the distributed micro-inverter 100 is connected to at least one new energy power generation unit, the distributed micro-inverter 100 is wirelessly connected to the control center 101, and the AC output of the distributed micro-inverter 100 is connected in parallel to the AC bus.

[0076] See attached Figure 2In some embodiments, the distributed micro-inverter 100 is configured as follows:

[0077] Continuously monitor the synchronization signal broadcast by the control center 101;

[0078] In response to receiving the synchronization signal, synchronizing the output voltage, phase and frequency according to the instruction of the synchronization signal;

[0079] In response to not receiving the synchronization signal, performing synchronization with reference to a phase on the AC bus;

[0080] In response to not receiving the synchronization signal and failing to detect the phase on the AC bus, the output is cut off.

[0081] In some embodiments, the distributed micro-inverter 100 is further configured to:

[0082] Continuously monitoring the first control instruction sent independently by the control center 101;

[0083] In response to receiving the first control instruction, the output voltage, phase and frequency are synchronized according to the instruction of the first control instruction, or the phase on the AC bus is referenced for synchronization, or the output is cut off.

[0084] In some embodiments, the distributed micro-inverter 100 is also configured with a local reference clock, which can maintain a frequency deviation of no more than 1% of the 50Hz / 60Hz industrial frequency in a short period of time (such as 500 seconds). After each synchronization, the distributed micro-inverter 100 can maintain the output AC frequency based on the internal local reference clock.

[0085] As for the generation of the synchronization signal, the broadcast frequency, and the limiting features of the first control instruction, etc., reference may be made to the above embodiments and no further details will be given here.

[0086] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A collaborative method for large-scale distributed micro-inverters under unreliable communication, wherein: Each distributed micro-inverter is connected to at least one new energy power generation unit, each distributed micro-inverter is wirelessly connected to the control center, and the AC output of each distributed micro-inverter is connected in parallel to the AC bus; characterized in that the coordination method includes: Each distributed micro-inverter respectively monitors the synchronization signal broadcast by the control center; The distributed micro-inverter receiving the synchronization signal synchronizes the output voltage, phase and frequency according to the instruction of the synchronization signal; The distributed micro-inverters that have not received the synchronization signal are synchronized with reference to the phase on the AC bus; The distributed micro-inverter that has not received the synchronization signal and has failed to detect the phase on the AC bus cuts off output.

2. The collaborative method according to claim 1, characterized in that: Also includes: The distributed micro-inverter that receives the first control instruction sent separately by the control center synchronizes the output voltage, phase and frequency according to the instruction of the first control instruction, or synchronizes with reference to the phase on the AC bus, or cuts off the output.

3. The collaborative method according to claim 1, characterized in that: Also includes: The distributed micro-inverter that has not received the synchronization signal continues to monitor the synchronization signal, and after receiving the synchronization signal, synchronizes the output voltage, phase and frequency according to the instruction of the synchronization signal.

4. The collaborative method according to claim 1, characterized in that: The synchronization signal is generated by the control center by comparing the voltage, frequency and phase indicated by the synchronization request with the voltage, frequency and phase monitored at the public grid access point.

5. The collaborative method according to claim 1, characterized in that: The synchronization signal is generated by the control center under the adopted synchronization clock.

6. The collaborative method according to claim 1 or 5, characterized in that: The synchronization signal is broadcast periodically by the control center.

7. A large-scale distributed micro-inverter cooperative system under unreliable communication, characterized in that: Each distributed micro-inverter is connected to at least one new energy power generation unit, each distributed micro-inverter is wirelessly connected to the control center, and the AC output of each distributed micro-inverter is connected in parallel to the AC bus; the control center is used to broadcast synchronization signals; Each of the distributed micro-inverters continuously monitors the synchronization signal broadcast by the control center; in response to receiving the synchronization signal, synchronizes the output voltage, phase and frequency according to the instructions of the synchronization signal; in response to not receiving the synchronization signal, synchronizes with reference to the phase on the AC bus; in response to not receiving the synchronization signal and failing to detect the phase on the AC bus, cuts off the output.

8. A distributed micro-inverter supporting synchronization under unreliable communication, wherein the distributed micro-inverter is connected to at least one new energy power generation unit, the distributed micro-inverter is wirelessly connected to a control center, and the AC output of the distributed micro-inverter is connected in parallel to the AC bus; characterized in that: The distributed micro-inverter is configured as: Continuously monitoring the synchronization signal broadcast by the control center; In response to receiving the synchronization signal, synchronizing the output voltage, phase and frequency according to the instruction of the synchronization signal; In response to not receiving the synchronization signal, performing synchronization with reference to a phase on the AC bus; In response to failure to receive the synchronization signal and failure to detect the phase on the AC bus, the output is cut off.

9. The distributed micro-inverter according to claim 8, characterized in that: The distributed micro-inverter is further configured as: Continuously monitoring the first control instruction sent separately by the control center; In response to receiving the first control instruction, the output voltage, phase and frequency are synchronized according to the instruction of the first control instruction, or the phase on the AC bus is referenced for synchronization, or the output is cut off.

10. The distributed micro-inverter according to claim 8 or 9, characterized in that: The distributed micro-inverter is further configured as: After each synchronization, the output frequency is maintained based on the internal local reference clock.

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