A predictive control method, device, equipment and medium for a three-level photovoltaic inverter

Abstract

This invention belongs to the field of power system control, specifically relating to a predictive control method, device, equipment, and medium for a three-level photovoltaic inverter. Based on the grid voltage, the inverter's three-phase output current, the DC-side voltage, the converter's three-phase output voltage, the α and β components of the grid voltage at time t, the α and β components of the inverter's output current, and the converter's three-phase output voltage, the α and β components of the predicted inverter output current at times t+1 and t+2 are calculated. Finally, the switching state at time t+1 under the condition of minimizing the target value is obtained. Based on the basic principle of FCS-MPC, predictive current control of the photovoltaic converter is achieved in a two-phase stationary coordinate system, effectively reducing the control parameters of the photovoltaic converter. Simultaneously, by setting an appropriate objective function, functions such as DC-side capacitor midpoint potential balance, reduced switching frequency, and reduced harmonic distortion rate are achieved. This effectively ensures safe system operation while extending the equipment's service life, demonstrating excellent application prospects.

Description

Technical Field

[0001] This invention belongs to the field of power system control, and specifically relates to a predictive control method, device, equipment and medium for a three-level photovoltaic inverter. Background Technology

[0002] Photovoltaic converters are mostly designed as two-level or three-level converters. Although traditional two-level converters have low construction costs, their DC-side capacitors have weak voltage withstand capability and are prone to breakdown when subjected to high voltage. In addition, the harmonic characteristics of the output of two-level converters are poor. In contrast, the voltage drop of the power transistor in the off state in a three-level converter is only half that of the DC-side voltage, and the harmonic characteristics are good.

[0003] Traditional three-level converters often employ dual-loop control, but this method suffers from numerous tuning parameters, leading to difficulties in parameter tuning and sensitivity to the main circuit. While three-level converters utilize dual-loop control and midpoint voltage balancing techniques, they suffer from several inherent drawbacks of traditional dual-loop control and require the use of multiple redundant small vectors, resulting in significant computational complexity and a complex structure. Summary of the Invention

[0004] This invention proposes a predictive control method, device, equipment, and medium for a three-level photovoltaic inverter, to solve the problems of complex control structure, too many parameters to be tuned, and complex modulation module design in the traditional dual closed-loop control strategy of NPC-type three-level photovoltaic inverters.

[0005] To achieve the above objectives, the present invention proposes the following technical solution:

[0006] A predictive control method for a three-level photovoltaic inverter includes the following steps:

[0007] Step 1: Obtain the predicted inverter output current values ​​at time t+1 and t+2;

[0008] Step 2, obtain the switch state value at time t+1 for the m-th type; m = 1,2……27；

[0009] Step 3: Obtain the predicted value of the voltage difference between the two capacitors on the DC side at time t+1;

[0010] Step 4: Obtain the predicted value of the voltage difference across the two capacitors on the DC side at time t+2. ；

[0011] Step 5: Obtain the switching frequency under various switching states at time t+1;

[0012] Step 6: Based on the predicted inverter output current, the m-th switching state value at t+1, the predicted voltage difference between the two capacitors on the DC side at times t+1 and t+2, and the switching frequency, establish an objective function and calculate the switching state at time t+1 when the objective function value is minimized. 。

[0013] Preferably, step 1 specifically involves obtaining the predicted values ​​of the inverter output current at time t+1 and time t+2. α、β Quantity i α (t+1)、i β (t+1)、i α (t+2)、i β (t+2)；

[0014] The specific formula is as follows:

[0015]

[0016] ；

[0017] In the formula, e α (t) and e β (t) They are respectively t The grid voltage at any given time α、β Quantity; i α (ten β (t) These are the inverter output currents. α、β Quantity; v α (t) , v β (t) These are the three-phase output voltages of the converter. i α (t+ 1)、i β (t+1)、i α (t+2)、i β (t+2) These are the predicted inverter output current values ​​at times t+1 and t+2, respectively. α、β Components; L is the filter inductance; R is the line resistance; C is the DC-side capacitor; T s The sampling period.

[0018] Preferably, step 2 specifically involves, according to the formula:

[0019]

[0020] Obtain the switch state variable Smx(t+1) at time t+1 for the m-th time.

[0021] In the formula x=a,b,c.

[0022] Preferably, step 3 specifically involves, according to the formula:

[0023] ;

[0024] Obtain the predicted value dUdc(t+1) of the voltage difference between the two capacitors on the DC side when the switch state is Sx(t) at time t+1;

[0025] In the formula, Udc1(t) and Udc2(t) are DC side voltages, ia(t), ib(t) and ic(t) are the three-phase output currents of the inverter, Ts is the sampling period, and C is the DC side capacitor;

[0026] Preferably, step 4 specifically involves, according to the formula:

[0027]

[0028] Obtain the predicted value of the voltage difference dUdcm (t+2) on the DC side of the two capacitors under the m-th switching state at time t+2;

[0029] In the formula, Udc1(t) and Udc2(t) are DC side voltages, ia(t), ib(t) and ic(t) are the three-phase output currents of the inverter, Ts is the sampling period, and C is the DC side capacitor; m=1,2……27.

[0030] Preferably, step 5 specifically involves, according to the formula

[0031]

[0032] Obtain the switching frequency of the three-level photovoltaic inverter device in the m-th switching state from time t to time t+1. n m sw (t)； In the formula: S m x (t+1) represents the m-th switch state value at t+1, S x (t) represents the switch state value at time t.

[0033] Preferably, step 6 specifically involves, according to the formula:

[0034]

[0035] Obtain target values ​​for 27 two-step predictive switching states. J m In the formula, , They are respectively t+1 The reference current is always at α、β Components in coordinate system λ 1 ,λ 2 ,λ 3 represents the weighting coefficients for control current, DC voltage imbalance, and switching frequency, respectively. i α (t+1)、i β (t+1)、i α (t+2)、i β (t+2) These are the predicted inverter output current values ​​at times t+1 and t+2, respectively. α、β Quantity; you dc (t+1) and you m dc (t+2) These are the predicted voltage differences across the two capacitors on the DC side at times t+1 and t+2, respectively; and the target values ​​based on 27 two-step predicted switching states. J m Select the switching states at time t+1 with the minimum target value according to the principle of minimum selection: Sx1(t+1), Sx2(t+1), Sx3(t+1), Sx4(t+1); return to step 1 to proceed to the next control time calculation.

[0036] A predictive control device for a three-level photovoltaic inverter includes: a current prediction value acquisition module, a switch state value acquisition module, a voltage difference prediction module, and an objective function module.

[0037] The current prediction value acquisition module is used to obtain the inverter output current prediction values ​​at time t+1 and t+2.

[0038] The switch state value acquisition module is used to acquire the switch state value at time t+1 of the m-th type; m=1,2……27;

[0039] The voltage difference prediction module is used to obtain the predicted value of the voltage difference between the two capacitors on the DC side at time t+1 and the predicted value of the voltage difference between the two capacitors on the DC side at time t+2.

[0040] The switching frequency acquisition module is used to acquire the switching frequency under various switching states at time t+1.

[0041] The objective function module is used to establish an objective function based on the predicted value of the inverter output current, the m-th switching state value at t+1, the predicted value of the voltage difference between the two capacitors on the DC side at times t+1 and t+2, and the switching frequency, and to find the switching state at time t+1 when the objective function value is minimized.

[0042] An electronic device includes a processor and a memory, wherein the processor executes a computer program stored in the memory to implement a predictive control method for a three-level photovoltaic inverter.

[0043] A computer-readable storage medium storing at least one instruction that, when executed by a processor, implements a predictive control method for a three-level photovoltaic inverter.

[0044] The advantages of this invention are:

[0045] Based on the basic principle of FCS-MPC, current prediction control of photovoltaic converters in a two-phase stationary coordinate system can be realized, which can effectively reduce the control parameters of photovoltaic converters. At the same time, by taking advantage of the advantages of FCS-MPC and setting an appropriate objective function, functions such as DC side capacitor midpoint potential balance, reduction of switching frequency and reduction of harmonic distortion rate can be achieved. This can effectively ensure the safe operation of the system and extend the service life of the equipment, and has a good application prospect. Attached Figure Description

[0046] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0047] Figure 1 This is a schematic diagram of a predictive control method for a three-level photovoltaic inverter;

[0048] Figure 2 This is a schematic diagram of the topology of a three-level photovoltaic inverter;

[0049] Figure 3 This is a schematic diagram of a predictive control device for a three-level photovoltaic inverter. Detailed Implementation

[0050] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0051] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this invention is for describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0052] Example 1:

[0053] Please see Figure 1 As shown, the present invention provides a predictive control method for a three-level photovoltaic inverter, comprising the following steps:

[0054] Step 1: Measure and record the current time. t Below: Grid voltage e a (tea b (tea c (t) Inverter three-phase output current i a (ten b (ten c (t)， DC side voltage U dc1 (t)、U dc2 (t)， Three-phase output voltage of the converter v a (t) , v b (t)、 , v c (t) Using the Clark transform, we obtain t The grid voltage at any given time α、β Quantity e α (tea β (t) Inverter output current α、β Quantity i α (ten β (t) The three-phase output voltage of the converter v α (t) , v β (t)；

[0055] The predicted inverter output current at times t+1 and t+2 can be calculated using the following formula. α、β Quantity i α (t+1)、i β (t+1)、i α (t+2)、i β (t+2) :

[0056]

[0057]

[0058] e a 、e b 、e c This refers to the grid voltage. i a 、i b 、i c This is the three-phase output current; U dc1 、U dc2 This is the DC side voltage; i pv To provide current output for photovoltaic cells; i dc This is the DC-side output current; v a , v b , v c These represent the three-phase output voltages of the converter (a, b, and c); L is the filter inductance; R is the line resistance; and C is the DC-side capacitor. S x1 -S x4 For power switching devices, S x (t) represents the state value of the switching device at time t, where x = a,b,c .

[0059] Step 2: Iterate through the switching states at time t+1 in the 27 cases, and use the following formula to calculate the switching state variable S at time t+1 for the m-th case. m x (t+1):

[0060]

[0061] Step 3: Based on the three-phase output current of the inverter recorded in Step 1 ia (ten b (ten c (t) and DC side voltage U dc1 (t)、U dc2 (t) The switch state at time t+1 can be calculated using the following formula: x (t) Predicted value of the voltage difference across the two capacitors on the DC side you dc (t+1)

[0062]

[0063] Step 4: Based on the predicted value of the voltage difference across the two capacitors on the DC side at time t+1 calculated in Step 3. you dc (t+ 1)， Combining the 27 switching states calculated in step two, the predicted value based on time t+1 is obtained using the following formula. you dc (t+1) At time t+2, the first m(m=1,2……27) Predicted value of the voltage difference across the two capacitors on the DC side under the switching state you m dc (t +2)：

[0064] ;

[0065] Step 5: Based on the m-th switching state value S obtained in Step 2 at the current time t+1 m x (t+1), combined with the switch state value S at time t. x (t), use the following formula to calculate the switching frequency of the m-th switching state of the NPC-type three-level photovoltaic inverter device from time t to time t+1. n m sw (t) :

[0066] ;

[0067] Based on the predicted inverter output current values ​​at times t+1 and t+2 in step one α、β Quantity i α (t+1)、 i β(t+1) Step 3: Predicted value of the voltage difference across the two capacitors on the DC side at time t+1. you dc (t+1) And the predicted value of the voltage difference between the two capacitors on the DC side at time t+2. you m dc (t+2) Step 4: Calculate the switching frequencies of the NPC-type three-level photovoltaic inverter devices under various switching states at time t+1. n m sw (t) The target values ​​for 27 two-step predictive switching states are calculated using the following formula. J m :

[0068]

[0069] In the formula , for t+1 The reference current is always at α、β Components in coordinate system λ 1 ,λ 2 ,λ 3 represents the weighting coefficients for control current, DC voltage imbalance, and switching frequency, which are typically taken as follows: λ 1 = 1.0 λ 2 = 1.0 λ 3 = 0.005;

[0070] Based on 27 target values ​​in the two-step prediction of the switching state J m The switching state at time t+1 is selected according to the principle of minimum selection, where the target value is minimized. S x1 (t+1)、S x2 (t+1)、S x3 (t+1)、S x4 (t+1) Return to step one to proceed to the next control time calculation.

[0071] Example 2:

[0072] like Figure 3 As shown, the present invention provides a predictive control device for a three-level photovoltaic inverter, comprising: a current prediction value acquisition module, a switch state value acquisition module, a voltage difference prediction module, and an objective function module.

[0073] The current prediction value acquisition module is used to obtain the inverter output current prediction values ​​at time t+1 and t+2.

[0074] The switch state value acquisition module is used to acquire the switch state value at time t+1 of the m-th type; m=1,2……27;

[0075] The voltage difference prediction module is used to obtain the predicted value of the voltage difference between the two capacitors on the DC side at time t+1 and the predicted value of the voltage difference between the two capacitors on the DC side at time t+2.

[0076] The switching frequency acquisition module is used to acquire the switching frequency under various switching states at time t+1.

[0077] The objective function module is used to establish an objective function based on the predicted value of the inverter output current, the m-th switching state value at t+1, the predicted value of the voltage difference between the two capacitors on the DC side at times t+1 and t+2, and the switching frequency, and to find the switching state at time t+1 when the objective function value is minimized.

[0078] Example 3:

[0079] The present invention provides a predictive control electronic device for a three-level photovoltaic inverter, the electronic device comprising a storage device, at least one processor, and a computer program stored in the storage device and executable on the processor.

[0080] The memory can be used to store the computer program. The processor implements the method steps of the grid dispatching method for new energy consumption scenarios described in Embodiment 1 by running or executing the computer program stored in the memory and calling the data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created according to the use of the electronic device 100 (such as audio data), etc. In addition, the memory may include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other non-volatile solid-state storage device.

[0081] The at least one processor may be a central processing unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), or field-programmable gate arrays (FPGAs). Programmable Gate Array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor can be a microprocessor or any thermal power plant processor, etc. The processor is the control center of the electronic device, connecting all parts of the electronic device through various interfaces and lines.

[0082] The memory in the electronic device stores multiple instructions to implement a grid dispatching method for renewable energy consumption scenarios, and the processor can execute the multiple instructions to achieve the following:

[0083] Obtain the predicted values ​​of the inverter output current at time t+1 and t+2;

[0084] Obtain the switch state value at time t+1 for the m-th type; m=1,2……27;

[0085] Obtain the predicted value of the voltage difference between the two capacitors on the DC side at time t+1;

[0086] Obtain the predicted value of the voltage difference between the two capacitors on the DC side at time t+2;

[0087] Obtain the switching frequency under various switching states at time t+1;

[0088] Based on the predicted output current of the inverter, the m-th switching state value at t+1, the predicted voltage difference between the two capacitors on the DC side at times t+1 and t+2, and the switching frequency, an objective function is established, and the switching state at time t+1 with the objective function value minimized is obtained.

[0089] Example 4:

[0090] If the modules / units integrated in the electronic device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium.

[0091] Based on this understanding, the present invention can implement all or part of the processes in the above-described embodiments by instructing related hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, and a read-only memory (ROM). OnlyMemory).

[0092] This invention designs a control strategy for an NPC three-level photovoltaic inverter based on finite control set model predictive control (FCS-MPC). Based on the fundamental principles of FCS-MPC, it achieves predictive current control of the photovoltaic converter in a two-phase stationary coordinate system, effectively reducing the control parameters of the photovoltaic converter. Simultaneously, leveraging the advantages of FCS-MPC, by setting an appropriate objective function, it achieves functions such as DC-side capacitor midpoint potential balance, reduced switching frequency, and reduced harmonic distortion rate. This effectively ensures safe system operation while extending the equipment's service life, demonstrating excellent application prospects.

[0093] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are included in this invention.

[0094] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0095] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0096] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0097] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A three-level photovoltaic inverter predictive control method, characterized in that, The method comprises the following steps: Step 1, obtaining the inverter output current prediction value at t+1 and t+2; Step 2, obtain the mth switch state value at time t+1; m= 1,2……27； Step 3, obtaining the prediction value of the voltage difference on the two capacitors on the DC side at t+1; Step 4, obtain the predicted value of the voltage difference on the two capacitors on the DC side at time t+2 ； Step 5, obtaining the switching frequency under various switching states at t+1; Step 6, establishing a target function according to the inverter output current prediction value, the mth switching state value at t+1, the prediction value of the voltage difference on the two capacitors on the DC side at t+1 and t+2, and the switching frequency, and solving the switching state at t+1 under the minimum case of the target function value; Step 6 is specifically, according to the formula: Obtaining 27 target values in two-step prediction switching state J m , wherein, , are respectively t+1 components of the reference current in the α-β coordinate at the moment, α、β are respectively λ 1 , λ 2 , λ 3weight coefficients of the control current, DC voltage imbalance and switching frequency; i α (t +1)、i β (t+1), i α (t+2), i β (t+2) are the predicted values of the inverter output current at time t+1 and t+2 respectively; α、β components; dU dc (t+1) and dU m dc (t+2) are the predicted values of the voltage difference on the two capacitors on the DC side at time t+1 and t+2 respectively; according to the target values in 27 kinds of two-step prediction switching states J m , the switching states at time t+1 when the target value is in the minimum case are selected according to the minimum selection principle: Sx1(t+1), Sx2(t+1), Sx3(t+1), Sx4(t+1); return to step 1 to calculate the next control time; is the switching frequency under the mth switching state.

2. The predictive control method of a three-level photovoltaic inverter according to claim 1, characterized in that, Step 1 is specifically to obtain the inverter output current prediction value at t+1 time and t+2 time α、β component i α (t+1), i β (t+1), i α (t+ 2)、i β (t+2)； The specific formula is: ； wherein e α (t) and e β (t) are respectively t components of the grid voltage at time instant t; α、β i α (t), i β (t) are respectively α、β components of the inverter output current; v α (t) , v β (t) are respectively three-phase output voltages of the converter, i α (t+1), i β (t+1), i α (t+2), i β (t+2) are respectively α、β components of the inverter output current prediction values at time instants t+1 and t+2.​ L is a filter inductance; R is a line resistance; C is a DC side capacitance; T s is a sampling period.

3. The predictive control method of a three-level photovoltaic inverter according to claim 1, characterized in that, Step 2 is specifically, according to the formula: Obtain the mth switching state variable Smx(t+1) at t+1; In the formulae x=a, b, c.

4. The predictive control method of a three-level photovoltaic inverter according to claim 3, characterized in that, Step 3 is specifically, according to the formula: ； Obtain the prediction value dUdc(t+1) of the voltage difference on the two capacitors on the DC side under the switching state Sx(t) at t+1; In the formula, Udc1(t) and Udc2(t) are the DC side voltage, ia(t), ib(t) and ic(t) are the inverter three-phase output current, Ts is the sampling period, and C is the DC side capacitor.

5. The predictive control method of a three-level photovoltaic inverter according to claim 3, characterized in that, Step 4 is specifically, according to the formula: Obtain the prediction value dUdcm(t+2) of the voltage difference on the two capacitors on the DC side under the mth switching state at t+2; In the formula, Udc1(t) and Udc2(t) are the DC side voltage, ia(t), ib(t) and ic(t) are the inverter three-phase output current, Ts is the sampling period, C is the DC side capacitor, and m=1, 2……27.

6. The predictive control method of a three-level photovoltaic inverter according to claim 1, wherein, Step 5 is specifically, according to the formula Obtaining the switching frequency of the third level photovoltaic inverter device in the mth switching state from time t to time t+1 n m sw (t)； In the formula: S m x (t+1) is the mth switching state value of t+1, S x (t) is the switching state value at time t.

7. A three-level photovoltaic inverter predictive control device for implementing the three-level photovoltaic inverter predictive control method of any one of claims 1-6, characterized in that, It comprises: The current prediction value acquisition module, the switching state value acquisition module, the voltage difference prediction module and the target function module; The current prediction value acquisition module is used for obtaining the inverter output current prediction value at t+1 and t+2; The switching state value acquisition module is used for obtaining the mth switching state value at t+1; m=1, 2……27; The voltage difference prediction module is used for obtaining the prediction value of the voltage difference on the two capacitors on the DC side at t+1 and the prediction value of the voltage difference on the two capacitors on the DC side at t+2; The switching frequency acquisition module is used for obtaining the switching frequency under various switching states at t+1; The target function module is used for establishing a target function according to the inverter output current prediction value, the mth switching state value at t+1, the prediction value of the voltage difference on the two capacitors on the DC side at t+1 and t+2, and the switching frequency, and solving the switching state at t+1 under the minimum case of the target function value.

8. An electronic device, comprising: The electronic device comprises a processor and a memory, and the processor is used for executing a computer program stored in the memory to realize the three-level photovoltaic inverter prediction control method in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer readable storage medium stores at least one instruction, and the at least one instruction is executed by the processor to implement the three-level photovoltaic inverter predictive control method in any one of claims 1-6.

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