JP5634561B1 - Monitoring device for solar power generation system - Google Patents

Abstract

An operation state of each string STi (i = 1, 2,... N) is accurately determined with a simple configuration. A current detection member 11 for detecting a current value Ii (i = 1, 2,... N) of each string STi and a microcomputer 21 for reading the current value Ii through a multiplexer 22 The computer 21 relatively evaluates each string STi based only on the current value Ii. [Selection] Figure 1

Description

  The present invention relates to a monitor device for a photovoltaic power generation system capable of individually monitoring a plurality of strings formed by connecting a plurality of solar cell modules in series.

  In the photovoltaic power generation system, the required number of multiple solar cells is collected and protected with resin, tempered glass, metal frames, etc., and modularized, and multiple solar cell modules thus modularized are connected in series. In general, a string is configured, and a plurality of strings are connected in parallel for each connection box via a diode for preventing backflow, and the generated power is used as AC power by connecting to a power conditioner. In addition, since the power generation capability of solar cell modules may be reduced due to aging or dirt, a monitor device for detecting a power generation failure string including such a solar cell module has been proposed (for example, Patent Document 1). ).

  The conventional monitor device measures the current value of each string connected in parallel and the voltage value common to each string, and determines the power generation amount of each string. On the other hand, a small solar panel for detecting the current amount of solar radiation is provided, the predicted power generation amount of each string is obtained based on the current amount of solar radiation, and the amount of solar radiation changes by comparing with the power generation amount of each string It is possible to correctly detect and specify a power generation failure string by correcting the change in the power generation amount due to the power generation.

JP2013-84759A

  When using such a conventional technology, it is difficult to sufficiently increase the calculation accuracy of the predicted power generation amount of each string based on the current solar radiation amount, and the power generation amount of each string is calculated in addition to the solar panel for detecting the solar radiation amount. This requires a current detector and a voltage detector, and the overall configuration tends to be complicated.

  Therefore, in view of the problems of the prior art, the object of the present invention is to calculate the standard value and upper / lower limit value for determination based only on the current value of each string, thereby operating each string with a simple configuration. An object of the present invention is to provide a monitor device for a photovoltaic power generation system that can determine the situation with practically sufficient accuracy.

  In order to achieve the above object, a configuration of the present invention is a monitor device for a photovoltaic power generation system that monitors and evaluates each string of 4 to 16 circuits connected to a single junction box. A current detection member for detecting a current value; and a microcomputer for reading the current value from each current detection member via a multiplexer. The microcomputer calculates an average value excluding the maximum value and the minimum value of each current value. Calculates the standard deviation of each current value as well as the standard value, and shifts by the equivalent of the standard deviation above and below the first upper limit value and lower limit value that shift by the allowable value above and below the standard value, respectively. The second upper limit value and the lower limit value are set, and a string whose current value falls within at least one of the first upper limit value, the lower limit value, the second upper limit value, and the lower limit value is determined to be normal. Rutotomoni, the current value is the first upper limit value, lower limit value, the second upper limit, and its gist that alarm to the outside is determined as abnormal strings deviating both lower limit.

  The microcomputer can be provided with a lamp display that displays a list of determination results of each current value for both the first upper limit value, the lower limit value, the second upper limit value, and the lower limit value.

  The microcomputer may be provided with a numeric display for displaying the standard value, and the microcomputer may switch and display each current value on the numeric display by manual operation.

  Further, the microcomputer may be provided with a changeover switch for selecting and setting an allowable value by manual operation.

  According to the configuration of the invention, the microcomputer reads the current value of each string detected by each current detection member and compares it with the first and second upper limit values and lower limit values above and below the standard value, The operating status of each string can be monitored. At this time, the microcomputer adopts the average value excluding the maximum value and minimum value of each current value as a standard value and relatively evaluates each string. For example, the string is configured such as the amount of solar radiation and the outside air temperature. Even if an external factor that affects the power generation capability of the solar cell module that fluctuates varies, the operating status of each string is not erroneously determined. However, by limiting the number of strings to be monitored to a small number such as 4, 8, 12, and 16 circuits, the microcomputer includes only solar cell modules whose external factors are substantially the same. It is preferable to make it. The number of solar cell modules in series per string is, for example, 14 pieces.

  On the other hand, the allowable value for determining the first upper limit value and the lower limit value can be manually set arbitrarily, for example, 5 to 50% of the standard value. In addition, by setting the second upper limit value and lower limit value based on the standard deviation of each current value, even if each current value fluctuates due to an accidental cause such as noise, a sound string is erroneously identified as abnormal. Opportunities for judgment can be reduced. However, when determining the second upper limit value and the lower limit value, the standard deviation may be multiplied by an appropriate correction coefficient.

  The lamp indicator attached to the microcomputer can display a list of the determination results of each current value, that is, the operating status of each string, and identify an abnormal string at a glance.

  The numerical display attached to the microcomputer can display the standard value or display the current value of each string by manual operation, thereby displaying the operation status of the microcomputer. Further, the microcomputer can arbitrarily select and set an allowable value for calculating the first upper limit value and the lower limit value by manually operating the attached changeover switch.

Overall block diagram Program flow chart Numerical data example (1) Numerical data example (2) Front view of sub panel

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The monitoring device for the photovoltaic power generation system includes a current detection member 11, 11... That detects a current value Ii (i = 1, 2,... N) of each string STi (i = 1, 2,... N), and a microcomputer 21. Are housed in the connection box B for the string STi. Here, n is the number of strings STi connected to a single junction box B.

  Each string STi is formed by connecting a predetermined number of photovoltaic modules 12, 12,... In series. The output of each string STi is individually introduced into the connection box B and connected in parallel via the switch DS, the backflow prevention diode D, and the current detection member 11, and is also connected to the common circuit breaker CB and external output. The terminal T is connected to a power conditioner (not shown) directly or via another connection box. The current detection member 11 may be a low resistance in series in order to detect each current value Ii, for example, a clamp-type current detector using a Hall element. The clamp-type current detector is advantageous when incorporated in an existing junction box B.

  The microcomputer 21 can read the current value Ii of each string STi detected by each current detection member 11 via the multiplexer 22 and the AD converter 23. The microcomputer 21 sends the control signal Sc to the multiplexer 22 to operate the multiplexer 22.

  A manually operated push button switch SW and a changeover switch SS are connected to the microcomputer 21. Further, the microcomputer 21 is provided with a lamp display 24 and a number display 25. For example, the lamp indicator 24 arranges red, green and orange LED lamps corresponding to each string STi in three rows and n stages from the top to the bottom so that the current value Ii of each string STi is “low” (L, red), The operation status of each string STi can be displayed in a list by displaying whether it is “standard” (S, green) or “high” (U, orange). The microcomputer 21 can send an alarm signal Sa and a necessary data signal Sd to the outside via terminals T1 and T2, respectively.

  The operation of the microcomputer 21 is, for example, as shown in the program flowchart of FIG. However, it is assumed that the program of FIG. 2 is repeatedly activated at predetermined time intervals of, for example, several tens of seconds to several minutes.

  First, the program reads and stores the current value Ii of each string STi via the multiplexer 22 and the AD converter 23 (program step (1) in FIG. 2, hereinafter simply expressed as (1)).

Subsequently, the program extracts the maximum value Imx and the minimum value Imn from the read current values Ii, and calculates the average value Ia, the standard value Io, and the standard deviation Is (2). However, the average value Ia = ΣIi / n is a simple average value of each current value Ii, and the standard value Io = (ΣIi−Imx−Imn) / (n−2), which is the maximum from each current value Ii. It is an average value excluding the value Imx and the minimum value Imn. The average value Ia is used to calculate the standard deviation Is = (Σ (Ii-Ia) ² / n) ^1/2 .

  Thereafter, the program uses the standard value Io and the allowable value d manually set via the external change-over switch SS, so that the first lower limit value I1a = Io-dIo for determination 1 and the first upper limit value are set. In addition to setting I1b = Io + dIo (3), using the standard value Io and standard deviation Is, set the second lower limit value I2a = Io-Is and the second upper limit value I2b = Io + Is for judgment 2. To do. However, the change-over switch SS is, for example, a 10-contact rotary switch, and the allowable value d = 0.05 to 0.5 (5 to 50%) is stepped by 0.05 (5%) by manual operation. Can be selected and set.

  Subsequently, the program compares each current value Ii with the first lower limit value I1a, the upper limit value I1b, the second lower limit value I2a, and the upper limit value I2b, and executes determination 1 and determination 2 (4). The string STi of the current value Ii that deviates from both of the determination 2 is determined to be abnormal (5), the standard value Io is displayed on the numeric display 25, and the determination result is displayed in a list on the lamp display 24 (6). If necessary, the alarm signal Sa and the data signal Sd are sent to the outside and the process is terminated. The alarm signal Sa includes, for example, the number of the string STi determined to be abnormal, the current value Ii, and the deviation direction of the current value Ii. The data signal Sd includes each current value Ii, standard value, and so on. It is assumed that the determination results of Io, first lower limit value I1a, upper limit value I1b, second lower limit value I2a, upper limit value I2b, determination 1, and determination 2 are included. However, as the alarm signal Sa, only the occurrence fact of the string STi determined to be abnormal may be output to the outside by, for example, a contact signal. Further, each time the current value Ii of each string STi is read, the data signal Sd may always output each current value Ii to the outside. When the push button switch SW is manually operated, the current value Ii of each string STi is sequentially switched and displayed on the numeric display 25 instead of the standard value Io.

  An example of numerical data of data processing contents according to the program flowchart of FIG. 2 is shown in FIGS. However, in FIGS. 3 and 4, the string STi is 16 circuits numbered 1 to 16 and n = 16.

  FIG. 3A shows one set of current values Ii of each string STi read into the microcomputer 21. FIG. Therefore, from the current value Ii in FIG. 3A, the maximum value Imx = I1 = 5.50A, the minimum value Imn = I5 = 3.11A, the average value Ia = 4.90A, the standard value Io = 4.98A, standard Deviation Is = 0.51A is obtained (FIG. 3B), and first lower limit value I1a = 4.73A and upper limit value I1b = 5.23A for determination 1 are obtained (FIG. 3C). The second lower limit value I2a = 4.47A and the upper limit value 5.49A for determination 2 are obtained (FIG. 3D). However, the first lower limit value I1a and the upper limit value I1b in FIG. 3B are calculated as an allowable value d = 0.05 (5%).

  Subsequently, each current value Ii in FIG. 3 (A) is compared with the first lower limit value I1a and upper limit value I1b in FIG. 3 (C), and the second lower limit value I2a and upper limit value I2b in FIG. 3 (D). When determination 1 and determination 2 are executed, FIG. 4 is obtained. However, in FIG. 4, U (high), S (standard), and L (low) in each column of determination 1 and determination 2 indicate that each current value Ii has a range from the first lower limit value I1a to the upper limit value I1b. It deviates upward, belongs within the range, deviates downward, and each current value Ii deviates upward from the range of the second lower limit value I2a to the upper limit value I2b, belongs to the range, and deviates downward It shows that.

  Therefore, in the final determination, in both the determination 1 and the determination 2, the string STi of the current value Ii deviating upward or downward may be extracted as abnormal and the other strings STi may be made normal. In FIG. 4, the string ST1 with number 1 and the string ST5 with number 5 are determined to be U (high) and L (low) abnormalities, respectively. Further, the current value I13 = 4.62A of the string ST13 of No. 13 deviates downward in the determination 1, but belongs to the range in the determination 2, so the final determination is also set to S (standard) and normal. It has been determined.

  FIG. 5 is an example of the sub panel SP for the monitor device. Such a sub-panel SP can be installed at an easy-to-see location in the connection box B in which the monitor device is incorporated. However, the function, form, arrangement, and the like of each member on the sub panel SP are merely examples, and can be arbitrarily changed.

  In the above description, the microcomputer 21 preferably completes a series of data processing of the program flowchart of FIG. 2 within a short time of at least about 1 second. This is because by shortening the series of data processing times, it is possible to reduce the chance of erroneous determination due to changes over time such as the outside air temperature and the amount of solar radiation.

  Further, the microcomputer 21 omits the setting of the first and second upper limit values I1b and I2b in the program step (3) of FIG. 2, and each current value in the determination 1 and determination 2 of the program step (4). Only the downward deviation of Ii may be checked. Furthermore, the microcomputer 21 may execute only one of the determination 1 and the determination 2 instead of executing both the determination 1 and the determination 2 in the program step (4) of FIG.

  The present invention can be widely and suitably applied to solar power generation systems of all power generation scales from household use to industrial use.

B ... Junction box SS ... Changeover switch STi (i = 1, 2, ... n) ... String Ii (i = 1, 2, ... n) ... Current value Imx ... Maximum value Imn ... Minimum value Io ... Standard value Is ... Standard deviation I1a ... first lower limit value I1b ... first upper limit value I2a ... second lower limit value I2b ... second upper limit value d ... allowable value 11 ... current detection member 21 ... microcomputer 22 ... multiplexer 24 ... lamp indicator 25 ... Number display

Patent Applicant Axon Data Machine Co., Ltd.

Claims (5)

A monitoring device for a photovoltaic power generation system that relatively evaluates and monitors each string of 4 to 16 circuits connected to a single junction box, and includes a current detection member that detects a current value of each string, and a multiplexer And a microcomputer for reading a current value from each of the current detection members, and the microcomputer uses the average value excluding the maximum value and the minimum value of each current value as a standard value and a standard deviation of each current value. And a first upper limit value and a lower limit value that are shifted above and below the standard value by an amount equivalent to the allowable value, and a second upper limit value and a lower limit value that are shifted above and below the standard value by an amount equivalent to the standard deviation, respectively. A string whose current value belongs to at least one of the first upper limit value, the lower limit value, the second upper limit value, and the lower limit value is determined to be normal, and the current value is the first upper limit value ,under Value, the second upper limit value, the monitoring device for photovoltaic power generation system characterized by alarm to the outside is determined as abnormal strings deviating both lower limit.   2. The microcomputer is provided with a lamp indicator for displaying a list of determination results of current values for both the first upper limit value, the lower limit value, the second upper limit value, and the lower limit value. The monitoring apparatus for solar power generation systems of description.   The monitor device for a photovoltaic power generation system according to claim 1 or 2, wherein a numerical indicator for displaying a standard value is attached to the microcomputer.   The monitor device for a photovoltaic power generation system according to claim 3, wherein the microcomputer switches and displays each current value on the numeric display by manual operation.   The monitor device for a photovoltaic power generation system according to any one of claims 1 to 4, wherein a changeover switch for selecting and setting an allowable value by manual operation is attached to the microcomputer.

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