Method and system for dynamically adjusting power of string type photovoltaic inverter square matrix

Abstract

The invention discloses a power dynamic adjustment method and system for a string type photovoltaic inverter matrix, and the method comprises the steps: obtaining a power adjustment value Pset of the matrix and a total power value Preal of an inverter which is in normal communication and is in a power adjustable state, and carrying out the power adjustment: a, when the Preal is a value 0, carrying out the distribution according to a corresponding power distribution expression; b, when the Preal is larger than 0, the communication is normal, and the real-time power values of the inverters in the power adjustable state are all larger than 0, distribution is carried out according to a corresponding power distribution expression; and c, when the Preal is greater than 0, the real-time power values of the inverters in normal communication and power adjustable states are 0, and the total target power is set to be greater than the total real-time power, distributing the target power to the inverters with the real-time power values being 0 according to the condition a, distributing the total target set power values and the total real-time power of the remaining inverters according to the condition a, and distributing the target power according to the condition b. The method has the advantages of accurate power distribution and the like.

Description

Technical Field

[0001] The present invention mainly relates to the field of photovoltaic technology, and in particular to a method and system for dynamically adjusting power of a string-type photovoltaic inverter array. Background Art

[0002] A string photovoltaic power station is composed of multiple inverter arrays, each of which contains multiple independent small-capacity inverters. The communication equipment equipped in each array is responsible for collecting data from the inverters in its own array and other terminal devices and uploading them to the monitoring systems of the booster station. At the same time, it receives control and adjustment instructions from the system to control the inverters and other terminal devices. Due to resource constraints, the AGC / AVC, fast frequency and other systems of the booster station often only allocate power to the entire array. How to allocate power to each inverter requires the communication equipment itself to further subdivide the power to each inverter. The above solution has the following technical problems in application:

[0003] 1. There may be inverters with different rated powers in the array, and the ideal maximum output of each inverter is different.

[0004] 2. The number of photovoltaic modules connected to each inverter in the array is inconsistent, resulting in inconsistent output capacity of the inverter at the same time.

[0005] 3. Cloud cover, different installation locations of photovoltaic modules, etc. result in different light intensities for different photovoltaic modules.

[0006] 4. The inverter itself is not accurately controlled.

[0007] The above problems will affect the accuracy and timeliness of power regulation. For example, the commonly used average distribution method will have a large error within a certain range. Summary of the invention

[0008] In view of the technical problems existing in the prior art, the present invention provides a method and system for dynamically adjusting power of a string photovoltaic inverter array with precise target power distribution.

[0009] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0010] A method for dynamically adjusting power of a string photovoltaic inverter array comprises the following steps:

[0011] Get the total power regulation target value P of the string photovoltaic inverter array set , and calculate the single real-time power P of all inverters in the current string photovoltaic inverter array that have normal communication and are in power adjustable state k_real And the real-time total power value P real , and then divided into the following situations for power adjustment:

[0012] a. When P real The value is 0, and the inverter power distribution expression is as follows:

[0013]

[0014] Where P k_set is the set power of the inverter with address k; P k_e is the rated power of the inverter with address k; n is the number of the inverter with normal communication and adjustable power; the addresses of the inverters in the array are numbered from 1 to the maximum number;

[0015] b. When P real The inverter real-time power value is greater than 0, and the communication is normal and the power is adjustable. The inverter power distribution expression is as follows:

[0016]

[0017] Compare the target setting value P of each inverter respectively k_set and the maximum adjustable power P k_e ; If there is P k_set >P k_e , force the corresponding inverter to set the power to the maximum configurable power P k_set =P k_e ;

[0018] Target total value P set、 Real-time total power value P real Subtract the set power and real-time power of the inverter set to the maximum settable power respectively, obtain the total target set power value and total real-time power of the remaining inverters not set to the maximum settable power, and recalculate the power allocation of the remaining inverters not set to the maximum settable power until the target set value P of the remaining inverters is k_set Less than the maximum settable power P k_e Or there are no remaining inverters to calculate;

[0019] c. When P real When the real-time power value of the inverter is greater than 0, the communication is normal and the power is adjustable, and the real-time power value is 0, and the set total target power is greater than the total real-time power; first allocate the target power to the inverters with real-time power value of 0 according to situation a, subtract the set power and real-time power of these inverters, and get the total target set power value and total real-time power of the remaining inverters, and allocate the target power according to situation b.

[0020] Preferably, after the target power that needs to be set for each inverter is obtained, the set target power of the inverter is corrected.

[0021] Preferably, the specific process of correcting the set target power of the inverter is: the current real-time power of the inverter does not reach the specified dead zone range of the last set target power, and the current set target power is still greater than the current real-time value, and the actual set target power is corrected to the current real-time value plus a preset offset.

[0022] Preferably, the specific process of correcting the set target power of the inverter is as follows: adjusting the target total power value P of the photovoltaic inverter array set Make 1% compensation.

[0023] Preferably, the power adjustable state is a grid-connected power generation state or a power-limited shutdown state.

[0024] Preferably, the set target powers of all inverters are sequentially filled into a communication frame according to the communication protocol, and sent via a broadcast message, so that each inverter obtains its own set target power for adjustment.

[0025] The present invention also discloses a computer program product, comprising a computer program, wherein the computer program executes the steps of the method described above when executed by a processor.

[0026] The present invention further discloses a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described above are executed.

[0027] The present invention also discloses a power dynamic regulation system for a string photovoltaic inverter array, comprising a memory and a processor connected to each other, wherein a computer program is stored on the memory, and when the computer program is run by the processor, the steps of the method described above are executed.

[0028] Compared with the prior art, the advantages of the present invention are:

[0029] The power regulation method of the present invention comprehensively considers that the rated powers of array inverters may be different, the inverter string access is unbalanced, the photovoltaic module light shielding and other factors, and can still accurately allocate the target power; when the target power allocated by a single inverter exceeds its maximum power, the excess target power is transferred to the target power of other inverters; and it can solve the problem of power regulation errors caused by inaccurate power control of a single inverter itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the communication device in an embodiment of the present invention.

[0031] Figure 2 It is a diagram showing an embodiment of the communication device of the present invention in a specific application.

[0032] Figure 3The figure is a flow chart of a power regulation method in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0034] like Figure 1-Figure 2 The figure shows a string photovoltaic inverter array, in which the communication equipment in the communication box of each array sub-array periodically reads the real-time data of all inverters and uploads the processed data to each monitoring system according to the protocol. Systems such as AGC / AV allocate power based on the array as the smallest unit, and then send it to the communication equipment in the communication box of the array sub-array. The communication equipment allocates reasonable power to a single inverter in the array for communication control and adjustment based on the internal dynamic power allocation method.

[0035] like Figure 3 As shown, the method for dynamically adjusting the power of a string photovoltaic inverter array provided by an embodiment of the present invention specifically includes the following steps:

[0036] The communication device receives the total power adjustment target value P of the matrix from the upper system set At the same time, the real-time power P of all inverters in the current array that have normal communication and are in power adjustable state (grid-connected power generation state or power-limited shutdown state) is calculated k_real and the total value P real , power adjustment is divided into the following situations:

[0037] a. When P real The value is 0, and the inverter power distribution expression is as follows:

[0038]

[0039] Where P k_set is the set power of the inverter with address k; P k_e is the rated power of the inverter with address k, P i_e is the rated power of the inverter with address i between 0 and n. The inverter addresses in the array are numbered from 1 to the maximum number. n is the number of the inverter with normal communication and adjustable power.

[0040] b. When P real The inverter real-time power value is greater than 0, and the communication is normal and the power is adjustable. The inverter power distribution expression is as follows:

[0041]

[0042] Where P k_set is the set power of the inverter with address k; P k_realis the current real-time power of the inverter with address k, and is compared with the target setting value P of each inverter respectively. k_set and the rated power P of the inverter with address k k_e ; If there is P k_set >P k_e , force the corresponding inverter to set the power to the maximum configurable power P k_set =P k_e ;

[0043] Target total value P set、 Real-time total power value P real Subtract the set power and real-time power of the inverter set to the maximum settable power respectively, and obtain the total target set power value and total real-time power of the remaining inverters not set to the maximum settable power. Recalculate the power allocation of the remaining inverters according to the above formula until the target set value P of the remaining inverters not set to the maximum settable power is k_set Less than the maximum adjustable power P k_e Or there are no remaining inverters to calculate;

[0044] c. When P real When the real-time power value of the inverter is greater than 0, and the communication is normal and the power is adjustable, and the real-time power value of the inverter is 0, and the total target power is greater than the total real-time power; first, assign the target power to the inverters with real-time power value of 0 according to point 1, subtract the setting power and real-time power of these inverters, and get the total target setting power value and total real-time power of the remaining inverters. Then assign the target power according to point 2. Through power allocation, the target power that needs to be set for each inverter can be obtained.

[0045] Furthermore, using the above dynamic method, within the output range, if the inverter control accuracy error is large, especially when the actual power controlled by the inverter is always smaller than the set target power, when the AGC / AVC and other systems perform small fluctuation adjustments, the inverter power will be adjusted smaller and smaller, eventually causing the inverter to always operate in a low power state. Therefore, it is necessary to correct the inverter's target power setting:

[0046] Comprehensively consider the target setting power of the inverter in the previous cycle, the current real-time power, and the target power that needs to be set currently.

[0047] The first type of inverter has a current real-time power that does not reach the specified dead zone range of the last set target power, and the current set target power is still greater than the current real-time value. The actual set target power is corrected to the current real-time value plus a preset offset.

[0048] The second method is to correct the target power of the inverter. The specific process is: adjust the total target power value P of the photovoltaic inverter array set Make 1% compensation.

[0049] In specific applications, in order to ensure the adjustment speed, the target setting power of all inverters is filled into a communication frame in sequence according to the communication protocol, and sent through a broadcast message. Each inverter obtains its own target power for adjustment.

[0050] The power regulation method of the present invention comprehensively considers that the rated powers of array inverters may be different, the inverter string access is unbalanced, the photovoltaic module light shielding and other factors, and can still accurately allocate the target power; when the target power allocated by a single inverter exceeds its maximum power, the excess target power is transferred to the target power of other inverters; and it can solve the problem of power regulation errors caused by inaccurate power control of a single inverter itself.

[0051] The present invention also discloses a computer program product, including a computer program, which executes the steps of the above method when executed by a processor. The present invention further discloses a computer-readable storage medium, which stores a computer program, which executes the steps of the above method when executed by a processor. The present invention also discloses a power dynamic regulation system for a string photovoltaic inverter array, including an interconnected memory and a processor, the memory stores a computer program, and the computer program executes the steps of the above method when executed by the processor.

[0052] The product, medium and system of the present invention correspond to the above method and also have the advantages described in the above method.

[0053] The present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by hardware related to computer program instructions. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned method embodiment when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. Computer-readable storage media include: any entity or device that can carry computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. The memory is used to store computer programs and / or modules, and the processor implements various functions by running or executing computer programs and / or modules stored in the memory, and calling data stored in the memory. The memory may include high-speed random access memory and may also include non-volatile memory, such as a hard disk, an internal memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0054] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A method for dynamically adjusting power of a string photovoltaic inverter array, characterized in that: Includes steps: Get the total power regulation target value P of the string photovoltaic inverter array set , and calculate the single real-time power P of all inverters in the current string photovoltaic inverter array that have normal communication and are in power adjustable state k_real And the real-time total power value P real , and then divided into the following situations for power adjustment: a. When P real The value is 0, and the inverter power distribution expression is as follows: Where P k_set is the set power of the inverter with address k; P k_e is the rated power of the inverter with address k; n is the number of the inverter with normal communication and adjustable power; the addresses of the inverters in the array are numbered from 1 to the maximum number; b. When P real The inverter real-time power value is greater than 0, and the communication is normal and the power is adjustable. The inverter power distribution expression is as follows: Compare the target setting value P of each inverter respectively k_set and the maximum adjustable power P k_e ; If there is P k_set >P k_e , force the corresponding inverter to set the power to the maximum configurable power P k_set =P k_e ; Target total value P set , real-time total power value P real Subtract the set power and real-time power of the inverter set to the maximum settable power respectively, obtain the total target set power value and total real-time power of the remaining inverters not set to the maximum settable power, and recalculate the power allocation of the remaining inverters until the target set value P of the remaining inverters not set to the maximum settable power is k_set Less than the maximum settable power P k_e Or there are no remaining inverters to calculate; c. When P real When the real-time power value of the inverter is greater than 0, and the communication is normal and the power is adjustable, and the real-time power value is 0, and the set total target power is greater than the total real-time power, first allocate the target power to the inverters with real-time power value of 0 according to situation a, subtract the set power and real-time power of these inverters, and get the total target set power value and total real-time power of the remaining inverters, and allocate the target power according to situation b.

2. The method for dynamic power regulation of a string photovoltaic inverter array according to claim 1, characterized in that: After the target power that needs to be set for each inverter is obtained, the set target power of the inverter is corrected.

3. The method for dynamic power regulation of a string photovoltaic inverter array according to claim 2, characterized in that: The specific process of correcting the set target power of the inverter is as follows: if the current real-time power of the inverter does not reach the specified dead zone range of the last set target power, and the current set target power is still greater than the current real-time value, the actual set target power is corrected to the current real-time value plus the preset offset.

4. The method for dynamic power regulation of a string photovoltaic inverter array according to claim 3, characterized in that: The specific process of re-correcting the set target power of the inverter is as follows: the total power adjustment target value P of the photovoltaic inverter array set Make 1% compensation.

5. The method for dynamic power regulation of a string photovoltaic inverter array according to any one of claims 1 to 4, characterized in that: The power adjustable state is a grid-connected power generation state or a power-limited shutdown state.

6. The method for dynamic power regulation of a string photovoltaic inverter array according to any one of claims 1 to 4, characterized in that: The set target powers of all inverters are sequentially filled into a communication frame according to the communication protocol and sent through broadcast messages. Each inverter obtains its own set target power for adjustment.

7. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are performed.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the computer program performs the steps of the method according to any one of claims 1 to 6.

9. A power dynamic regulation system for a string photovoltaic inverter array, comprising a memory and a processor connected to each other, wherein a computer program is stored in the memory, characterized in that: When the computer program is executed by a processor, the computer program performs the steps of the method according to any one of claims 1 to 6.

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