Inverter parallel operation control method and device, inverter and storage medium

Abstract

The invention relates to the technical field of inverters, and discloses an inverter parallel operation control method and device, an inverter and a storage medium, and the method comprises the steps: calculating the average reactive power and the average active power of all inverters, carrying out the reactive droop adjustment of a target inverter based on the average reactive power, and obtaining a voltage amplitude value; and performing active droop adjustment on the target inverter based on the average active power to obtain a voltage phase, generating a reference voltage phase based on the voltage amplitude and the voltage phase, converting a reference voltage signal into a modulation signal by using closed-loop control, and finally performing modulation by using a preset modulation method based on the modulation signal to generate a switch control signal. According to the method, the amplitude of the output voltage is adjusted, the output power of each inverter is balanced, the voltage effective value is stable and the instantaneous value harmonic wave is low during the off-grid parallel operation of multiple inverters, and the method has the advantages that the control precision of average power control is higher than that of droop control, and the dynamic response is fast.

Description

Technical Field

[0001] The present invention relates to the technical field of inverters, and particularly to a control method, device, inverter and storage medium for parallel operation of inverters. Background Art

[0002] When multiple inverters operate in parallel off-grid, current sharing control is crucial for the stable operation of the parallel system. When the circulating current between inverters is too large, it will, at best, cause internal power consumption and affect system efficiency, and at worst, lead to system collapse. Therefore, how to control the balance of inverter output power and the stability of voltage output has become a problem to be solved. Summary of the Invention

[0003] In view of this, the present invention provides a control method, device, inverter and storage medium for parallel operation of inverters to solve the problem that when the circulating current between inverters is too large, it will, at best, cause internal power consumption and affect system efficiency, and at worst, lead to system collapse.

[0004] In a first aspect, the present invention provides a control method for parallel operation of inverters, the method comprising: calculating the average reactive power and average active power of all inverters; performing reactive droop regulation on a target inverter based on the average reactive power to obtain a voltage amplitude, and performing active droop regulation on the target inverter based on the average active power to obtain a voltage phase; generating a reference voltage signal based on the voltage amplitude and voltage phase; converting the reference voltage signal into a modulation signal by using closed-loop control; and modulating based on the modulation signal by using a preset modulation method to generate a switch control signal, where the switch control signal is used to control the operating state of the target inverter.

[0005] The control method for parallel operation of inverters provided by the present invention calculates the average reactive power and average active power of all inverters, performs reactive droop regulation on the target inverter based on the average reactive power to obtain a voltage amplitude, and performs active droop regulation on the target inverter based on the average active power to obtain a voltage phase. Based on the voltage amplitude and voltage phase, a reference voltage phase is generated. The reference voltage signal is converted into a modulation signal by using closed-loop control. Finally, based on the modulation signal, a switch control signal is generated by using a preset modulation method to adjust the output voltage amplitude, achieving the purpose of balanced output power, stable effective value of voltage and low instantaneous value harmonics of each inverter when multiple inverters operate in parallel off-grid, and having the advantages of higher control accuracy of average power control than droop control and faster dynamic response.

[0006] In an alternative embodiment, all inverters perform data interaction through a communication bus. Calculating the average reactive power and average active power of all inverters includes: when the AC voltage currently output by the target inverter is in a zero-crossing state, clearing the historical power information stored therein; sequentially reading the power information uploaded by each inverter during the previous power acquisition period from the communication bus, where the previous power acquisition period is the time period from when the previous output AC voltage was zero to when the current output AC voltage is zero; after the power information corresponding to all inverters is read, calculating the average reactive power and average active power based on the power information of all inverters; and uploading the power information of the current self-operation to the communication bus.

[0007] Based on the voltage being in a zero-crossing state, the present invention calculates the average reactive power and average active power corresponding to all inverters, which can ensure the synchronization of power information among the inverters, and then more accurately calculate the average power, thus improving the stability of the entire multi-inverter off-grid parallel operation.

[0008] In an alternative embodiment, the sequentially reading the power information uploaded by each inverter during the previous power acquisition period from the communication bus includes: when the time from the moment when the AC voltage currently output by the target inverter is in a zero-crossing state reaches a first operation time interval, starting to sequentially read the power information uploaded by each inverter during the previous power acquisition period from the communication bus, and sequentially reading the power information uploaded by each inverter during the previous power acquisition period based on the first operation time interval; the calculating the average reactive power and average active power based on the power information of all inverters after the power information corresponding to all inverters is read includes: when the time from the moment when the power information corresponding to the last inverter is read reaches a first operation time interval, calculating the average reactive power and average active power based on the power information of the inverter; the uploading the power information of the current self-operation to the communication bus includes: when the time from the moment when the average reactive power and average active power are calculated based on the power information of all inverters reaches a first operation time interval, uploading the power information of the current self-operation to the communication bus.

[0009] The present invention executes each step based on the operation time interval, realizing a fixed operation time interval and a clear step execution order, making the operation of calculating the average power, and then the parallel operation control of the inverter have high repeatability, facilitating the implementation of a standardized control strategy, and improving the stability and reliability of the entire operation control.

[0010] In an alternative embodiment, the reactive droop regulation of the target inverter based on the average reactive power to obtain the voltage amplitude includes: subtracting the current reactive power of the target inverter from the average reactive power to obtain a reactive power difference; using a proportional-integral controller to convert the reactive power difference into a voltage regulation value; adding the voltage regulation value to the given value of the effective value of the output voltage to obtain an effective voltage regulation value; multiplying the current reactive power of the target inverter by a preset reactive droop coefficient to obtain a first product, and subtracting the first product from the effective voltage regulation value to obtain an effective reference value of the voltage of the target inverter; subtracting the current effective value of the voltage of the target inverter from the effective reference value of the voltage to obtain an effective voltage error value; using a proportional-integral controller to convert the effective voltage error value into a voltage amplitude.

[0011] In an alternative embodiment, the active droop regulation of the target inverter based on the average active power to obtain the voltage phase includes: subtracting the current active power of the target inverter from the average active power to obtain an active power difference; using the proportional-integral controller to convert the active power difference into a phase regulation value; adding the phase regulation value to the phase given value to obtain a regulated phase given value; multiplying the current active power of the target inverter by a preset active droop coefficient to obtain a second product, and subtracting the second product from the regulated phase given value to obtain a phase reference value; using the sine function controller to convert the phase reference value into a voltage phase.

[0012] In an alternative embodiment, the conversion of the reference voltage signal into a modulation signal using closed-loop control includes: using voltage loop control to convert the reference voltage signal into a current reference value; using current loop control to convert the current reference value into a modulation signal.

[0013] In a second aspect, the present invention provides an inverter parallel operation control device, the device includes: a power average calculation module for calculating the average reactive power and average active power of all inverters; a droop regulation module for performing reactive droop regulation on the target inverter based on the average reactive power to obtain the voltage amplitude, and performing active droop regulation on the target inverter based on the average active power to obtain the voltage phase; a reference voltage signal generation module for generating a reference voltage signal based on the voltage amplitude and voltage phase; a modulation signal generation module for converting the reference voltage signal into a modulation signal using closed-loop control; an inverter control module for modulating based on the modulation signal using a preset modulation method to generate a switch control signal, and the switch control signal is used to control the operating state of the target inverter.

[0014] In a third aspect, the present invention provides an inverter, which includes a controller. The controller includes a memory and a processor, which are communicatively connected to each other. The memory stores computer instructions, and the processor executes the computer instructions to execute the parallel operation control method of the inverter according to the first aspect or any corresponding embodiment thereof.

[0015] In a fourth aspect, the present invention provides a computer-readable storage medium, on which computer instructions are stored. The computer instructions are used to cause a computer to execute the parallel operation control method of the inverter according to the first aspect or any corresponding embodiment thereof.

[0016] In a fifth aspect, the present invention provides a computer program product, including computer instructions, which are used to cause a computer to execute the parallel operation control method of the inverter according to the first aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 is a flowchart of the parallel operation control method of the inverter according to an embodiment of the present invention;

[0019] Figure 2 is a logic example diagram of droop control according to an embodiment of the present invention;

[0020] Figure 3 is a flowchart of another parallel operation control method of the inverter according to an embodiment of the present invention;

[0021] Figure 4 is a logic example diagram of average power control according to an embodiment of the present invention;

[0022] Figure 5 is a flowchart example diagram of average power calculation according to an embodiment of the present invention;

[0023] Figure 6 is a loop control example diagram of the parallel operation control of the inverter according to an embodiment of the present invention

[0024] Figure 7 is a structural block diagram of the inverter according to an embodiment of the present invention;

[0025] Figure 8It is a structural block diagram of a parallel operation control device for an inverter according to an embodiment of the present invention;

[0026] Figure 9 It is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. Specific embodiments

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] According to an embodiment of the present invention, an embodiment of a method for controlling parallel operation of inverters is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0029] In this embodiment, a method for controlling parallel operation of inverters is provided, which can be used for a target inverter. Among them, the target inverter is an inverter in a multi-inverter off-grid parallel system. Figure 1 It is a flowchart of a method for controlling parallel operation of inverters according to an embodiment of the present invention. As Figure 1 shown, the process includes the following steps:

[0030] Step S101, calculate the average reactive power and average active power of all inverters.

[0031] The embodiments of the present invention do not limit the manner of obtaining the power information of all inverters. A central controller can be established, and each inverter sends its own power information to the central controller through a communication network. The target inverter obtains the power information of all inverters from the central controller. It can also be that the inverters communicate with each other to exchange power information, and the target inverter can directly obtain the power information from other inverters. Only as an example, after the target inverter obtains the power information of all inverters, the active power and reactive power of all inverters can be added separately to obtain the total active power and total reactive power, and then the total power is divided by the number of inverters to obtain the average reactive power and average active power.

[0032] Step S102, perform reactive droop regulation on the target inverter based on the average reactive power to obtain the voltage amplitude, and perform active droop regulation on the target inverter based on the average active power to obtain the voltage phase.

[0033] In the embodiment of the present invention, the reactive droop regulation can be performed on the target inverter based on a preset reactive droop coefficient, the given effective value of the output voltage, the current reactive power and the average reactive power of the target inverter to obtain the voltage amplitude. In the embodiment of the present invention, the active droop regulation can be performed on the target inverter based on a preset active droop coefficient, the average active power, the current active power of the target inverter and the rated frequency to adjust the output frequency, and then adjust the voltage phase (the voltage phase is obtained by frequency integration), so that each parallel inverter can adjust the frequency and amplitude of the output voltage within a small range according to its own output active power and reactive power by using the droop control method, and finally achieve the current sharing operation of multi-machine parallel connection.

[0034] As Figure 2 shown, when the sum of the output impedance of the parallel inverter module and the connection impedance is inductive, and the phase and amplitude differences of the output voltages of each inverter are small, the phase difference of the output voltages between the modules determines the active circulating current of the parallel system, and the voltage amplitude determines the reactive circulating current of the system. The droop control equation is:

[0035] ω = ω * -m*P

[0036] E = E * -n*Q

[0037] where, ω represents the angular frequency after droop regulation; E represents the voltage amplitude after droop regulation; ω * represents the angular frequency of the reference voltage of the inverter; E * represents the amplitude of the reference voltage of the inverter; m represents the droop coefficient of the angular frequency, generally taking 0.02; n represents the droop coefficient of the voltage amplitude, generally taking 0.2; P represents the active power of the inverter; Q represents the reactive power of the inverter.

[0038] Step S103: Generate a reference voltage signal based on the voltage amplitude and the voltage phase.

[0039] In the embodiment of the present invention, the reference voltage signal can be directly generated according to the mathematical expression of the sinusoidal AC voltage signal by using the voltage amplitude and the voltage phase.

[0040] Step S104: Convert the reference voltage signal into a modulation signal by using closed-loop control.

[0041] In the embodiment of the present invention, based on the error between the reference voltage signal and the actual output voltage of the target inverter, the current reference value can be generated by using the voltage loop, and then based on the error between the current reference value and the actual output current of the target inverter, the modulation signal can be generated by using the current loop.

[0042] Step S105: Modulate based on the modulation signal using a preset modulation method to generate a switching control signal, where the switching control signal is used to control the operating state of the target inverter.

[0043] In the embodiments of the present invention, the preset modulation method is not limited. It can be single-phase full-bridge inverter SPWM modulation or three-phase inverter SVPWM modulation. By way of example only, the modulation signal can be modulated using the preset modulation method to generate a switching control signal, where the switching control signal can control the operating state of the target inverter.

[0044] The inverter parallel operation control method provided by the present invention calculates the average reactive power and average active power of all inverters, performs reactive droop regulation on the target inverter based on the average reactive power to obtain the voltage amplitude, and performs active droop regulation on the target inverter based on the average active power to obtain the voltage phase. Based on the voltage amplitude and voltage phase, a reference voltage phase is generated, and the reference voltage signal is converted into a modulation signal using closed-loop control. Finally, based on the modulation signal, modulation is performed using a preset modulation method to generate a switching control signal, and the output voltage amplitude is adjusted to achieve the purpose of balanced output power, stable RMS voltage, and low instantaneous value harmonics of each inverter during off-grid parallel operation of multiple inverters, and has the advantages of higher average power control accuracy and faster dynamic response than droop control.

[0045] In this embodiment, an inverter parallel operation control method is provided, which can be used for the target inverter. Figure 3 It is a flowchart of the inverter parallel operation control method according to the embodiments of the present invention, as Figure 3 shown. The process includes the following steps:

[0046] Step S301: Calculate the average reactive power and average active power of all inverters.

[0047] As Figure 4 shown, the average power control method is to share the power information between each power conversion system (PCS) in the parallel system using the CAN bus, and calculate the average power as a reference value to control the amplitude and phase angle of the output voltage, so as to evenly distribute the load current among the PCSs.

[0048] Specifically, all inverters perform data interaction through the communication bus. The above step S301 includes:

[0049] Step S3011: When the AC voltage currently output by the target inverter is in the zero-crossing state, clear the historical power information stored in itself.

[0050] Step S3012: Sequentially read the power information uploaded by each inverter during the previous power acquisition cycle from the communication bus, where the previous power acquisition cycle is the time period from when the previous output AC voltage was zero to when the current output AC voltage is zero.

[0051] Step S3013: After reading the power information corresponding to all inverters is completed, calculate the average reactive power and average active power based on the power information of all inverters.

[0052] Step S3014: Upload the power information of the current self - operation to the communication bus.

[0053] In the embodiments of the present invention, all inverters can perform power data interaction through a communication bus (which can be a CAN bus). To ensure the synchronization of power information between inverters, synchronous operations need to be performed on the CAN data transceiver of each inverter. Considering the power frequency synchronization between inverters, the zero - crossing point of the output voltage can be used as the reference point for data transceiver of each inverter. For example, Figure 5 as shown, when the AC voltage currently output by the target inverter (the target inverter is any one of the modules 1, 2... n in the attached figure (the module is the inverter), and the CAN data of the module includes power information) is in the zero - crossing state, execute step 0, the historical power information stored in itself can be cleared, and then step 1 can be executed from the CAN bus, that is, read the power information uploaded to the communication bus by the first inverter (all inverters can be sorted in any order) during the previous power acquisition cycle, and save it to its own cache. Then execute step 2, that is, read the power information uploaded to the communication bus by the second inverter during the previous power acquisition cycle and cache it, so as to sequentially read the power information uploaded to the communication bus by all inverters during the previous power acquisition cycle until the power information uploaded by all inverters is read (that is, step n is completed), then step n + 1 can be executed, calculate the average reactive power and average active power based on the power information of all inverters, and finally execute step n + 2, the target inverter uploads the current operating power information to the CAN bus. In this way, one cycle is completed. When the voltage of the target inverter is in the zero - crossing state next time, enter the next power acquisition cycle.

[0054] Based on the voltage being in the zero - crossing state, the present invention calculates the average reactive power and average active power corresponding to all inverters, which can ensure the synchronization of power information between inverters, and then more accurately calculate the average power, improving the stability of the off - grid parallel operation of the entire multi - inverter system.

[0055] Specifically, the power information uploaded by each inverter during the previous power acquisition cycle is sequentially read from the communication bus, including: when the moment when the AC voltage currently output by the target inverter is in the zero-crossing state reaches the first operating time interval, start sequentially reading the power information uploaded by each inverter during the previous power acquisition cycle from the communication bus, and sequentially read the power information uploaded by each inverter during the previous power acquisition cycle based on the first operating time interval; after the power information corresponding to all inverters is read, calculate the average reactive power and average active power based on the power information of all inverters, including: when the moment when the power information corresponding to the last inverter is read reaches the first operating time interval, calculate the average reactive power and average active power based on the power information of the inverter; upload the current self-running power information to the communication bus, including: when the moment when the average reactive power and average active power are calculated based on the power information of all inverters reaches the first operating time interval, upload the current self-running power information to the communication bus.

[0056] In an embodiment of the present invention, the operating time interval can be calculated based on the switching frequency of the Pulse Width Modulation (PWM). For example, if the PWM switching frequency is 10 kHz, the corresponding operating time interval is 100 us, and the interval between every two steps is 100 us, only for example; when the AC voltage output by the target inverter is in the zero-crossing state, its corresponding moment can be defined as the zero moment. After the first operating time interval, step 1 is executed. After the first operating time interval, step 2 is executed, that is, the interval between every two steps is the first operating time interval.

[0057] The present invention executes each step based on the operating time interval, realizing a fixed operating time interval and a clear step execution order, making the operation of calculating the average power, and then the parallel operation control of the inverters have high repeatability, facilitating the implementation of a standardized control strategy, and improving the stability and reliability of the entire operation control.

[0058] Step S302, perform reactive droop regulation on the target inverter based on the average reactive power to obtain the voltage amplitude, and perform active droop regulation on the target inverter based on the average active power to obtain the voltage phase.

[0059] Specifically, performing reactive power droop regulation on the target inverter based on the average reactive power to obtain the voltage amplitude includes: subtracting the current reactive power of the target inverter from the average reactive power to obtain a reactive power difference; using a proportional-integral controller to convert the reactive power difference into a voltage regulation value; adding the voltage regulation value to the given effective value of the output voltage to obtain an effective voltage regulation value; multiplying the current reactive power of the target inverter by a preset reactive power droop coefficient to obtain a first product, and subtracting the first product from the effective voltage regulation value to obtain an effective reference value of the voltage of the target inverter; subtracting the current effective value of the voltage of the target inverter from the effective reference value of the voltage to obtain an effective voltage error value; using a proportional-integral controller to convert the effective voltage error value into the voltage amplitude.

[0060] As Figure 6 shown, after obtaining the average reactive power and average active power information corresponding to all inverters in the embodiment of the present invention, the average reactive power can be subtracted from the real-time reactive power of the target inverter to obtain a reactive power difference, and a proportional-integral controller (PI controller) is used to convert the reactive power difference into a voltage regulation value, and the voltage regulation value is added to the given effective value of the output voltage to obtain an effective voltage regulation value, where the given effective value of the output voltage is related to the off-grid system of the inverter. For example, for a conventional 380W system, the given effective value of the voltage is 380W, which is only for illustration; at the same time, the real-time reactive power of the target inverter is multiplied by a preset reactive power droop coefficient Kq to obtain a first product, where the preset reactive power droop coefficient can be set according to the actual off-grid operation of the inverter, and generally about 0.2 can be taken; the first product is subtracted from the effective voltage regulation value to obtain an effective reference value of the voltage of the target inverter, and the effective reference value of the voltage is subtracted from the real-time effective value of the voltage of the target inverter to obtain an effective voltage error value, and finally the PI controller is used to convert the effective voltage error value into the voltage amplitude.

[0061] Specifically, performing active power droop regulation on the target inverter based on the average active power to obtain the voltage phase includes: subtracting the current active power of the target inverter from the average active power to obtain an active power difference; using a proportional-integral controller to convert the active power difference into a phase regulation value; adding the phase regulation value to the phase given value to obtain a regulated phase given value; multiplying the current active power of the target inverter by a preset active power droop coefficient to obtain a second product, and subtracting the second product from the regulated phase given value to obtain a phase reference value; using a sine function controller to convert the phase reference value into the voltage phase.

[0062] In an embodiment of the present invention, the calculated average active power is subtracted from the real-time active power of the target inverter to obtain an active power difference. Then, a PI controller is used to convert the active power difference into a phase adjustment value, and the phase adjustment value is added to the phase given value to obtain a phase given adjustment value, where the phase given value is obtained by integrating the voltage angular velocity given with respect to time. At the same time, the real-time active power of the target inverter is multiplied by a preset active power droop coefficient Kp to obtain a second product, where the preset active power droop coefficient is related to the actual off-grid parallel operation requirements of multiple inverters and is generally about 0.02. Then, the phase given adjustment value is subtracted from the second product to obtain a phase reference value. Finally, a sine function controller can be used to convert the phase reference value into a voltage phase.

[0063] Step S303: Generate a reference voltage signal based on the voltage amplitude and voltage phase. For details, please refer to Figure 1 Step S103 of the embodiment shown, which will not be elaborated here.

[0064] Step S304: Use closed-loop control to convert the reference voltage signal into a modulation signal.

[0065] Specifically, use voltage loop control to convert the reference voltage signal into a current reference value; use current loop control to convert the current reference value into a modulation signal.

[0066] As Figure 6 shown, the voltage loop of the embodiment of the present invention includes a PI controller, which subtracts the real-time voltage value of the target inverter from the reference voltage signal, and then uses the PI controller to convert it into a current reference value as the reference for the inner current loop. The feedback of the current loop is the inverter inductor current, which is output by the PI controller in the current loop and superimposed with the voltage instantaneous value feedforward to be used as the modulation signal.

[0067] Step S305: Based on the modulation signal, perform modulation using a preset modulation method to generate a switch control signal, which is used to control the operating state of the target inverter. For details, please refer to Figure 1 Step S105 of the embodiment shown, which will not be elaborated here.

[0068] In this embodiment, an inverter is also provided, as Figure 7 shown. The inverter includes a controller, and the controller includes a memory and a processor. The memory and the processor are communicatively connected to each other. The memory stores computer instructions, and the processor executes the computer instructions to execute the off-grid parallel operation control method of the inverter.

[0069] In this embodiment, a control device for parallel operation of inverters is further provided. This device is used to implement the above-mentioned embodiments and preferred implementation manners, and those that have been described will not be elaborated again. As used hereinafter, the term "module" can be a combination of software and / or hardware that can achieve a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0070] This embodiment provides a control device for parallel operation of inverters. As Figure 8 shown, it includes: a power averaging calculation module 801, configured to calculate the average reactive power and average active power of all inverters; a droop regulation module 802, configured to perform reactive droop regulation on a target inverter based on the average reactive power to obtain a voltage amplitude, and perform active droop regulation on the target inverter based on the average active power to obtain a voltage phase; a reference voltage signal generation module 803, configured to generate a reference voltage signal based on the voltage amplitude and voltage phase; a modulation signal generation module 804, configured to convert the reference voltage signal into a modulation signal by using closed-loop control; and an inverter control module 805, configured to perform modulation based on the modulation signal by using a preset modulation method to generate a switch control signal, and the switch control signal is used to control the operating state of the target inverter.

[0071] In some optional implementation manners, the power averaging calculation module 801 includes: a data clearing unit, configured to clear the stored historical power information when the AC voltage currently output by the target inverter is in a zero-crossing state; a power reading unit, configured to sequentially read the power information uploaded by each inverter during the previous power acquisition period from the communication bus, where the previous power acquisition period is the time period from the previous output of the AC voltage being zero to the current output of the AC voltage being zero; a power calculation unit, configured to calculate the average reactive power and average active power based on the power information of all inverters after the power information corresponding to all inverters is read; and a power uploading unit, configured to upload the current power information of its own operation to the communication bus.

[0072] In some alternative embodiments, the power information uploaded by each inverter during the previous power acquisition cycle is sequentially read from the communication bus, including: when the time when the AC voltage currently output by the target inverter is at the zero-crossing state reaches a first operation time interval, starting to sequentially read the power information uploaded by each inverter during the previous power acquisition cycle from the communication bus, and sequentially reading the power information uploaded by each inverter during the previous power acquisition cycle based on the first operation time interval; after the power information corresponding to all inverters is read, calculating the average reactive power and average active power based on the power information of all inverters, including: when the time when the power information corresponding to the last inverter is read reaches the first operation time interval, calculating the average reactive power and average active power based on the power information of the inverter; uploading the current self-running power information to the communication bus, including: when the time when the average reactive power and average active power are calculated based on the power information of all inverters reaches the first operation time interval, uploading the current self-running power information to the communication bus.

[0073] In some alternative embodiments, the droop regulation module 802 includes: a reactive power difference calculation unit for subtracting the current reactive power of the target inverter from the average reactive power to obtain a reactive power difference; a voltage regulation unit for converting the reactive power difference into a voltage regulation value by using a proportional-integral controller; a voltage effective regulation unit for adding the voltage regulation value to the given value of the effective value of the output voltage to obtain an effective voltage regulation value; a voltage effective reference calculation unit for multiplying the current reactive power of the target inverter by a preset reactive power droop coefficient to obtain a first product, and subtracting the first product from the effective voltage regulation value to obtain an effective voltage reference value of the target inverter; a voltage effective error calculation unit for subtracting the current effective value of the voltage of the target inverter from the effective voltage reference value to obtain an effective voltage error value; a voltage amplitude conversion unit for converting the effective voltage error value into a voltage amplitude by using a proportional-integral controller.

[0074] In some alternative embodiments, the droop regulation module 802 includes: an active power difference calculation unit for subtracting the current active power of the target inverter from the average active power to obtain an active power difference; a phase regulation unit for converting the active power difference into a phase regulation value by using a proportional-integral controller; a phase given regulation unit for adding the phase regulation value to the phase given value to obtain a phase given regulation value; a phase reference value calculation unit for multiplying the current active power of the target inverter by a preset active power droop coefficient to obtain a second product, and subtracting the second product from the phase given regulation value to obtain a phase reference value; a voltage phase conversion unit for converting the phase reference value into a voltage phase by using a sine function controller.

[0075] In some alternative embodiments, the modulation signal generation module 804 includes: a voltage loop control unit configured to convert a reference voltage signal into a current reference value by using voltage loop control; and a current loop control unit configured to convert the current reference value into a modulation signal by using current loop control.

[0076] The further function descriptions of the above-mentioned respective modules and units are the same as those in the corresponding embodiments above, and will not be elaborated herein.

[0077] The parallel operation control device of the inverter in this embodiment is presented in the form of functional units. Here, the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and a memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0078] An embodiment of the present invention further provides a computer device having the above-mentioned Figure 8 parallel operation control device of the inverter as shown.

[0079] Please refer to Figure 9 , Figure 9 FIG. is a schematic structural diagram of a computer device provided by an alternative embodiment of the present invention. As shown in Figure 9 , the computer device includes: one or more processors 10, a memory 20, and an interface for connecting each component, including a high-speed interface and a low-speed interface. Each component communicates with each other through different buses and can be installed on a common main board or installed in other ways according to needs. The processor can process instructions executed within the computer device, including instructions stored in the memory or on the memory to display graphical information of the GUI on an external input / output device (such as a display device coupled to the interface). In some alternative embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (such as an array of servers, a set of blade servers, or a multi-processor system). Figure 9 In FIG., one processor 10 is taken as an example.

[0080] The processor 10 can be a central processing unit, a network processor, or a combination thereof. Among them, the processor 10 can further include a hardware chip. The above-mentioned hardware chip can be an application specific integrated circuit, a programmable logic device, or a combination thereof. The above-mentioned programmable logic device can be a complex programmable logic device, a field programmable gate array, a general array logic, or any combination thereof.

[0081] Among them, the memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the methods shown in the above embodiments.

[0082] The memory 20 may include a program storage area and a data storage area. Among them, the program storage area may store an operating system and application programs required for at least one function; the data storage area may store data created according to the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some alternative embodiments, the memory 20 may optionally include a memory remotely provided with respect to the processor 10, and these remote memories may be connected to the computer device through a network. Examples of the above network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0083] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk, or a solid-state drive; the memory 20 may also include a combination of the above types of memories.

[0084] The computer device further includes an input device 30 and an output device 40. The processor 10, the memory 20, the input device 30, and the output device 40 may be connected through a bus or other means. Figure 9 Taking the connection through the bus as an example.

[0085] The input device 30 may receive input digital or character information, and generate key signal inputs related to the user settings and function controls of the computer device, such as a touch screen, a keypad, a mouse, a trackpad, a touchpad, a pointing stick, one or more mouse buttons, a trackball, a joystick, etc. The output device 40 may include a display device, an auxiliary lighting device (e.g., an LED), and a haptic feedback device (e.g., a vibration motor), etc. The above display device includes but is not limited to a liquid crystal display, a light-emitting diode, a display, and a plasma display. In some alternative embodiments, the display device may be a touch screen.

[0086] Embodiments of the present invention also provide a computer-readable storage medium. The method according to the embodiments of the present invention can be implemented in hardware, firmware, or be implemented as computer code that can be recorded on a storage medium, or be implemented as computer code that is originally stored in a remote storage medium or a non-transitory machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored as such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code, and when the software or computer code is accessed and executed by the computer, the processor, or the hardware, the method shown in the above embodiments is implemented.

[0087] A part of the present invention can be applied as a computer program product, such as computer program instructions, which when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should be able to understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to the computer.

[0088] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for controlling parallel operation of inverters, characterized in that: The method comprises: Calculate the average reactive power and average active power of all inverters; Performing reactive droop adjustment on the target inverter based on the average reactive power to obtain a voltage amplitude, and performing active droop adjustment on the target inverter based on the average active power to obtain a voltage phase; generating a reference voltage signal based on the voltage amplitude and the voltage phase; Converting the reference voltage signal into a modulation signal using closed-loop control; Based on the modulation signal, modulation is performed using a preset modulation method to generate a switch control signal, and the switch control signal is used to control the operating state of the target inverter.

2. The method according to claim 1, characterized in that All inverters exchange data via a communication bus. The calculation of the average reactive power and average active power of all inverters includes: When the AC voltage currently output by the target inverter is in a zero-crossing state, the historical power information stored in itself is cleared; The power information uploaded by each inverter in the last power acquisition cycle is sequentially read from the communication bus, wherein the last power acquisition cycle is a time period from the last output AC voltage being zero to the current output AC voltage being zero; After the power information corresponding to all inverters is read, the average reactive power and the average active power are calculated based on the power information of all inverters; Upload the current power information of its own operation to the communication bus.

3. The method according to claim 2, characterized in that The step of sequentially reading the power information uploaded by each inverter in the last power acquisition cycle from the communication bus comprises: when the time when the AC voltage currently output by the target inverter is in a zero-crossing state reaches a first operation time interval, starting to sequentially read the power information uploaded by each inverter in the last power acquisition cycle from the communication bus, and sequentially reading the power information uploaded by each inverter in the last power acquisition cycle based on the first operation time interval; After the power information corresponding to all inverters is read, the average reactive power and the average active power are calculated based on the power information of all inverters, including: when the time from the moment when the power information corresponding to the last inverter is read reaches the first operation time interval, the average reactive power and the average active power are calculated based on the power information of the inverter; The uploading of the current power information of its own operation to the communication bus includes: when the time from the moment when the average reactive power and the average active power are calculated based on the power information of all inverters reaches the first operation time interval, uploading the current power information of its own operation to the communication bus.

4. The method according to claim 1, characterized in that: The step of performing reactive droop adjustment on the target inverter based on the average reactive power to obtain a voltage amplitude includes: Subtracting the average reactive power from the current reactive power of the target inverter to obtain a reactive power difference; Converting the reactive power difference into a voltage regulation value using a proportional-integral controller; Adding the voltage regulation value to the given output voltage effective value to obtain the voltage effective regulation value; Multiplying the current reactive power of the target inverter by a preset reactive droop coefficient to obtain a first product, and subtracting the effective voltage regulation value from the first product to obtain an effective voltage reference value of the target inverter; Subtracting the voltage effective reference value from the current voltage effective value of the target inverter to obtain a voltage effective error value; The voltage effective error value is converted into a voltage amplitude by using a proportional-integral controller.

5. The method according to claim 1, characterized in that The step of performing active droop adjustment on the target inverter based on the average active power to obtain a voltage phase includes: Subtracting the average active power from the current active power of the target inverter to obtain an active power difference; Using a proportional-integral controller, converting the active power difference into a phase adjustment value; Adding the phase adjustment value to the phase given value to obtain the phase given adjustment value; Multiplying the current active power of the target inverter by a preset active droop coefficient to obtain a second product, and subtracting the given phase adjustment value from the second product to obtain a phase reference value; The phase reference value is converted into a voltage phase using a sine function controller.

6. The method according to claim 1, characterized in that The method of converting the reference voltage signal into a modulation signal by closed-loop control includes: Converting the reference voltage signal into a current reference value by using a voltage loop control; The current reference value is converted into a modulation signal by using current loop control.

7. An inverter parallel operation control device, characterized in that: The device comprises: The power average calculation module is used to calculate the average reactive power and average active power of all inverters; A droop adjustment module, configured to perform reactive droop adjustment on the target inverter based on the average reactive power to obtain a voltage amplitude, and perform active droop adjustment on the target inverter based on the average active power to obtain a voltage phase; A reference voltage signal generating module, used for generating a reference voltage signal based on the voltage amplitude and voltage phase; A modulation signal generating module, used for converting the reference voltage signal into a modulation signal by closed-loop control; The inverter control module is used to perform modulation based on the modulation signal using a preset modulation method to generate a switch control signal, wherein the switch control signal is used to control the operating state of the target inverter.

8. An inverter, characterized in that: The inverter includes a controller, and the controller includes a memory and a processor. The memory and the processor are communicatively connected to each other, and computer instructions are stored in the memory. The processor executes the inverter parallel operation control method described in any one of claims 1 to 6 by executing the computer instructions.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the inverter parallel operation control method according to any one of claims 1 to 6.

10. A computer program product, characterized in that The method comprises computer instructions, wherein the computer instructions are used to enable a computer to execute the inverter parallel operation control method according to any one of claims 1 to 6.

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