KR101870346B1 - Fault diagnosis method of multi string solar cells connected to multi string solar inverter - Google Patents

Abstract

The present invention relates to a multistring solar cell fault diagnosis method.
The present invention relates to a solar power generation system, comprising: a power generation amount sampling step of measuring power generation amount at each sampling time for each string channel constituting a multistring solar cell; calculating a ratio of increase / decrease of current power generation amount, A pattern matching rate calculation step of calculating a pattern matching rate of the fault diagnosis arrangement information acquired for each of the string channels, and a step of calculating a pattern matching rate of the string channel having the pattern matching rate lower than the reference value as a fault channel And a failure determination step of determining a failure state.
According to the present invention, it is possible to automatically diagnose which string in a multistring solar cell has failed and display it to the manager, thereby improving the efficiency and convenience of the operation and maintenance of the power generation system.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a multistring solar cell connected to a multistring solar inverter,

The present invention relates to a multistring solar cell fault diagnosis method connected to a multistring solar inverter. More particularly, the present invention relates to a multistring solar cell fault diagnosis method capable of enhancing efficiency and convenience in operation and maintenance of a power generation system by automatically diagnosing which string in a multistring solar cell has caused a fault.

Since the output of one solar cell currently used in solar power generation is very small, a solar cell module (PV module: Photovoltaic Module) is constructed by connecting several solar cells in order to efficiently obtain the required output . Although the power generated from one solar cell module has a larger capacity than that of a single solar cell, it can be used as a power source for a small-sized device, and the amount of power required to supply generated power to a general commercial power system is inevitable.

For this reason, when a power system is to be connected to a power system, several solar modules may be connected in one group, or a plurality of such groups may be connected in parallel to form a solar array (PV array) And the voltage and electric power required for transmission are ensured. In order to secure the voltage and power, it is common that a solar cell module is connected in series to form a string, and a plurality of strings are grouped into a solar cell array, which is called a multistring solar cell.

In the case of multistring solar inverters that support multiple solar input channels, there are various detection methods and display functions for the product's own circuit abnormality or over the input / output range. However, It is difficult to detect the abnormality and the failure of the multistring solar cell connected to the photovoltaic cell.

As described above, the prior art fails to provide a function of automatically diagnosing which string of the multistring solar cell has a failure, thereby reducing efficiency related to the operation and maintenance of the power generation system.

Korean Patent Laid-Open Publication No. 10-2009-0101338 (Published Date: September 25, 2009, entitled: Method for operating a multistring inverter for a photovoltaic generator) Korean Registered Patent No. 10-1282993 (Registered Date: June 28, 2013, Name: Multi Inverter Solar Photovoltaic System)

An object of the present invention is to provide a multistring solar cell fault diagnosis method capable of improving the efficiency and convenience of operation and maintenance of a power generation system by automatically diagnosing which string in a multistring solar cell has caused a fault.

In addition, the present invention displays the string position to be checked in the inverter product itself when a certain solar string string abnormality or failure occurs in a medium / large-sized solar power generation system composed of multiple solar strings, And to provide a multistring solar cell fault diagnosis method capable of repairing a faulty solar cell.

In order to solve the above problems, the present invention provides a multistring solar cell fault diagnosis method for diagnosing a fault state of a multistring solar cell connected to a multistring solar inverter, comprising the steps of: A failure diagnosis array information generation step of calculating the increase / decrease ratio of the present generation power generation amount relative to the immediately preceding generation power generation for each string channel and arranging the increase / decrease ratio to generate the failure diagnostic array information; A pattern matching rate calculation step of calculating a pattern matching rate of the acquired fault diagnosis arrangement information, and a fault determination step of determining a string channel having a pattern matching rate lower than a reference value as a fault channel.

The multistring solar cell fault diagnosis method according to the present invention further includes a fault location information providing step of providing location information of the string channel determined to be in the fault state.

In the multistring solar cell fault diagnosis method according to the present invention, in the fault diagnosis array information generation step, the increase / decrease ratio is calculated until the number of increase / decrease ratios included in the fault diagnosis array information becomes a specified number or more, To the fault diagnosis arrangement information.

In the multistring solar cell fault diagnosis method according to the present invention, in the fault diagnosis arrangement information generation step, the fault diagnosis arrangement information is generated by arranging the increase / decrease ratio in a time-series manner corresponding to the sampling time .

According to the present invention, it is possible to provide a multistring solar cell fault diagnosing method capable of enhancing efficiency and convenience in operation and maintenance of a power generation system by automatically diagnosing which string in a multistring solar cell has caused a fault.

In addition, in a medium / large size photovoltaic power generation system composed of multiple solar strings, when a certain solar string string abnormality or failure occurs, the position of the string to be checked in the inverter product itself is displayed, A solar cell fault diagnosis method is provided.

1 is a diagram showing an exemplary configuration of a multi-string solar inverter system to which an embodiment of the present invention is applied,
2 is a diagram illustrating a method of diagnosing a multistring solar cell fault according to an embodiment of the present invention,
3 is a diagram illustrating an example of power generation amount information sampled for each string channel constituting a multistring solar cell in the power generation amount sampling step according to an embodiment of the present invention,
4 is a diagram for explaining a method of generating fault diagnosis arrangement information in the fault diagnosis arrangement information generating step in an embodiment of the present invention.

It is to be understood that the specific structural or functional description of embodiments of the present invention disclosed herein is for illustrative purposes only and is not intended to limit the scope of the inventive concept But may be embodied in many different forms and is not limited to the embodiments set forth herein.

The embodiments according to the concept of the present invention can make various changes and can take various forms, so that the embodiments are illustrated in the drawings and described in detail herein. It should be understood, however, that it is not intended to limit the embodiments according to the concepts of the present invention to the particular forms disclosed, but includes all modifications, equivalents, or alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms may be named for the purpose of distinguishing one element from another, for example, without departing from the scope of the right according to the concept of the present invention, the first element may be referred to as a second element, The component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that no other element exists in between. Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having" and the like are used to specify that there are features, numbers, steps, operations, elements, parts or combinations thereof described herein, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning of the context in the relevant art and, unless explicitly defined herein, are to be interpreted as ideal or overly formal Do not.

The present invention is a technology that can be directly applied to a multistring solar inverter, and is a technology that can determine whether a solar cell string connected to an inverter is faulty during a power generation operation, not a failure diagnosis of the inverter itself.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings, in which: FIG.

According to the present invention, the discriminating operation is performed by calculating the real-time power generation amount of the multistring input of each channel through the current and voltage measurement, calculating the real-time power generation amount as the increase / decrease ratio with respect to the previous time power generation amount, and converting it into a product of a predetermined scale factor And creates an array element for that time channel. If a certain number of arrays are secured, the pattern is compared with each other to compute the matching rate to determine whether there is a channel that does not meet the reference value. If an undersupplied channel occurs, And check alarms to indicate the location of the suspected faulty channel.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram illustrating an exemplary configuration of a multistring solar inverter system to which an embodiment of the present invention is applied. FIG. 2 is a diagram illustrating a method for diagnosing a multistring solar cell fault according to an exemplary embodiment of the present invention.

1 and 2, an embodiment of the present invention is a multistring solar cell fault diagnosis method for diagnosing a fault state of a multistring solar cell connected to a multistring solar inverter, wherein the power generation sampling step (S20, S30) (Step S40), a pattern matching rate calculation step S60, a failure determination step S70, and a failure location information providing step S80.

In step S10, the operation of the multistring solar inverter is started.

In the power generation amount sampling step (S20, S30), the power generation amount sampling unit performs the process of measuring the power generation amount at each sampling time for each string channel constituting the multistring solar cell.

For example, the power generation amount sampling steps S20 and S30 may be configured to include S20 and S30.

In step S20, a process of determining whether the current time corresponds to the sampling time is performed, and the process proceeds to step S30 if the current time corresponds to the sampling time.

In step S30, a process of measuring the power generation amount for each string channel constituting the multistring solar cell is performed by the power generation amount sampling unit. For example, the power generation amount may be configured to be measured at an output end of a multistring solar cell, that is, at an input end of an MPPT (Maximum Power Point Tracker) performing a maximum power follow-up function.

3 is a diagram illustrating power generation amount information sampled for each string channel constituting a multistring solar cell in the generation amount sampling step (S20, S30).

3, the power generation amount is sampled at N sampling points for each of the string channels, and according to the example of FIG. 3, the power generation amount pattern of the string 4 is different from the strings 1, 2, and 3. The power generation amount sampled at N sampling points for each string channel is converted into fault diagnosis array information, which is an element for diagnosing a fault through a fault diagnosis array information generating step (S40) described later.

In the fault diagnosis array information generation step S40, the fault diagnosis array information generation unit calculates the increase / decrease ratio of the present time generation volume with respect to the immediately preceding generation volume for each string channel, and generates the fault diagnosis array information by arranging the increase / decrease ratio .

In addition, referring to FIG. 4, which is a drawing for explaining a method for generating the fault diagnosis array information in the fault diagnosis array information generating step (S40), when the present time is 2 and the last time is 1, Can be expressed by the following equation (1).

In Equation (1), SF is a scale factor, Power (1) is power generation at the immediately preceding power, and Power (2) is power generation at the current power generation.

In the fault diagnosis array information generation step (S40), the fault diagnosis array information is generated by arranging the increase / decrease ratios in a time-series manner corresponding to the sampling time.

For example, in the fault diagnosis array information generation step S40, the fault diagnosis array information generator repeatedly calculates the increase / decrease ratio until the number of increase / decrease ratios included in the fault diagnosis array information becomes equal to or greater than the specified number, Information. ≪ / RTI >

As a result of the comparison in the step S50, when the number of increase / decrease ratios included in the failure diagnosis arrangement information is equal to or larger than the designated number, that is, the marginal number or more, it is regarded that sufficient judgment data is obtained and the process proceeds to the pattern matching rate calculation step S60 do.

In the pattern matching rate calculation step S60, the pattern matching rate calculation unit calculates the pattern matching rate of the fault diagnosis array information acquired for each string channel.

As described above with reference to FIG. 3, the generation patterns of the strings 4 are different from the strings 1, 2, and 3, respectively. Therefore, a similar pattern difference also occurs in the fault diagnosis array information generated on the basis of the power generation amount sampled at N sampling points for each string channel. That is, the pattern of the diagnostic diagnostic array information obtained from the string 4 differs from that of the strings 1, 2, and 3.

In the failure determination step S70, a process of determining a string channel whose pattern matching rate of the failure diagnosis array information acquired for each string channel is less than a reference value as a failure channel is performed. If it is determined that the failure has occurred, the process returns to the failure location information providing step S80.

In the fault location information providing step S80, a process of providing the location information of the string channel determined by the fault location information providing unit as a faulty state is performed. For example, location information of a string channel determined to be in a fault state can be visually provided through a user interface screen provided in the inverter.

As described above in detail, according to the present invention, a multistring solar cell fault diagnosis method capable of improving the efficiency and convenience in the operation and maintenance of the power generation system by automatically diagnosing which string in the multistring solar cell has caused a fault There is an effect provided.

In addition, in a medium / large size photovoltaic power generation system composed of multiple solar strings, when a certain solar string string abnormality or failure occurs, the position of the string to be checked in the inverter product itself is displayed, A solar cell fault diagnosis method is provided.

S20, S30: Generation amount sampling step
S40: Fault diagnosis array information generation step
S60: Pattern matching rate calculation step
S70: Fault determination step
S80: Fault location information providing step

Claims (4)

A multistring solar cell fault diagnosis method for diagnosing a fault state of a multistring solar cell connected to a multistring solar inverter,
A generation amount sampling step of measuring a generation amount at each sampling time for each string channel constituting the multistring solar cell;
A fault diagnosis array information generation step of calculating a ratio of increase / decrease of current generation power with respect to the immediately preceding generation power of each string channel and arranging the increase / decrease ratio to generate fault diagnosis array information;
A pattern matching rate calculating step of calculating a pattern matching rate of the fault diagnosis arrangement information acquired for each of the string channels; And
And determining that the string channel whose pattern matching rate is less than the reference value is a faulty channel,
In the fault diagnosis arrangement information generating step,
The increase / decrease ratio is calculated and added to the failure diagnostic array information until the number of increase / decrease ratios included in the failure diagnosis array information becomes equal to or greater than the designated number, and the increase / decrease ratio is arranged in a time series corresponding to the sampling time Thereby generating the fault diagnosis arrangement information. The method according to claim 1,
Further comprising a failure location information providing step of providing location information of the string channel determined to be in the failure state. delete delete

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