JP6560079B2 - Photovoltaic power generation system, power supply device and method for diagnosing solar power generation means - Google Patents

Description

  The present invention relates to a photovoltaic power generation system and a power supply device, and more particularly to a photovoltaic power generation system having a function of diagnosing output performance, a power supply device used therefor, and a method for diagnosing photovoltaic power generation means.

  In the solar power generation system, the abnormality of the solar panel leads to a decrease in the amount of power generation, and the lost profit increases as the state continues. Therefore, to detect abnormalities of solar panels and solar strings that combine multiple solar panels at an early stage, or quickly determine that the power generation performance shows a tendency to deteriorate and is below the guaranteed level. is important.

  By the way, the generated power of a solar panel or a solar string (hereinafter collectively referred to as a solar power generation means) is defined by the received solar radiation intensity and the element temperature. In general, the solar power generation means is installed outdoors, and the solar radiation intensity changes every moment, and the element temperature of the solar cell constituting the solar power generation means also changes every moment depending on the solar radiation intensity, air temperature, wind and the like.

  Therefore, conventionally, for diagnosing abnormalities in the solar power generation means, a global solarimeter and a thermometer are required to observe changes in solar radiation intensity and element temperature. For example, in Patent Document 1, the amount of solar radiation and temperature around the solar cell is measured by the measurement data acquisition unit, the maximum operating point is estimated using the measured environmental data, and whether the solar cell is in an abnormal state or not. Is judged.

Japanese Patent No. 5581965

  However, the amount of solar radiation changes drastically, and may change greatly within, for example, one second. As a result, a time difference is generated between the measurement time of the solar radiation intensity by the solar radiation meter and the measurement time of the characteristic (for example, maximum power) of the solar power generation means. In the prior art described in Patent Document 1, estimation of the maximum operating point based on the solar radiation intensity may not be accurately performed due to this time difference, and abnormality determination may not be accurately performed. More specifically, for example, when the amount of solar radiation decreases, the solar power generation power may drop before the measurement value of the solar radiation intensity by the pyranometer decreases, and the abnormality determination may not be performed accurately.

  Furthermore, in the case of storing and comparing measurement data for the purpose of confirming the aging degradation of the output performance of the solar power generation means, including data that may not reflect the solar radiation intensity correctly, It may not be possible to correctly grasp the aging deterioration state.

  As for the thermometer, as disclosed in Patent Document 1, it is common to measure the temperature around the solar panel or pinpoint a predetermined point of the solar panel. However, it may be difficult to accurately measure the panel temperature according to the temperature around the solar panel. Even when the panel temperature is measured at a pinpoint, the solar panel has a certain size, so that the solar panel has a certain area, for example, a position away from the point where the thermometer is installed in the solar panel. Depending on the position, there may be a difference between the actual temperature and the measured temperature. When the photovoltaic power generation system becomes large like the mega solar system that has been increasing in recent years, the number of solar panels and solar strings increases, and thus the deviation of the measured temperature is further increased. As a countermeasure, it is conceivable to increase the number of thermometers. However, there is a problem that such a thermometer that requires accurate measurement is expensive, and there is a problem that an increase in the number of measurement points increases the cost. As for the pyranometer, if the number of installations is increased in order to increase the measurement accuracy, the same cost problem occurs.

  Furthermore, for example, in the circuit design in the power conditioner, it may be necessary to examine an additional circuit that does not affect the measurement depending on the arrangement of the pyranometer and the thermometer.

  In view of the above problems, an object of the present invention is to more accurately diagnose the output performance of the solar power generation means without using a special measuring device such as a solar radiation meter or a thermometer.

  In the photovoltaic power generation system according to the present invention, the control unit that controls the power supply device moves the operating point of the photovoltaic power generation means to a greater extent than at the time of MPPT (Maximum Power Point Tracking) control. The detected value of the input current and the input voltage is acquired from the output, and at least one of the solar radiation intensity and the temperature of the photovoltaic power generation means is estimated based on the detected value, and the output performance of the photovoltaic power generation means is calculated using the estimated value. Is configured to diagnose.

  According to this aspect, the output performance of the photovoltaic power generation means can be diagnosed based on the detected values of the input voltage and the input current at the operating point that is moved more greatly than during MPPT control. That is, the output performance of the solar power generation means can be diagnosed without using a special measurement device (additional measurement device) such as a pyranometer and / or thermometer.

  That is, in the first aspect of the present invention, there is provided a solar power generation system including a solar power generation unit, a power supply device that converts the output of the solar power generation unit, and a control unit that controls the power supply device, The power supply apparatus includes switch means provided between output terminals of the solar power generation means, and detection means for detecting an input current and an input voltage from the solar power generation means, and the control unit is in a normal mode. The MPPT control for searching for the maximum power point by moving the operating point of the solar power generation means by the on / off control of the switch means is performed, while the MPPT control is performed on the operating point in the diagnostic mode of the solar power generation means. Move more than the time, obtain detection values from the detection means at the maximum power point and the moved operating point within a predetermined period, and at the moved operating point Estimating at least one of the solar radiation intensity and temperature of the photovoltaic power generation means based on the output value, correcting the reference maximum power set in advance based on the estimated value, and correcting the corrected maximum power value And the output performance of the said photovoltaic power generation means is diagnosed based on the detected value in the said maximum power point.

  According to this aspect, in the diagnostic mode, the control unit estimates the solar radiation intensity and / or temperature of the solar power generation means based on the input voltage and the detected value of the input current at the operating point moved more than at the time of MPPT control. . Then, the reference maximum power is corrected using the estimated value to diagnose the output performance of the photovoltaic power generation means. That is, the output performance of the solar power generation means can be diagnosed without using a special measurement device (additional measurement device) such as a pyranometer and / or thermometer. Note that the power supply device configured to be capable of MPPT control has detection means for detecting the input voltage and input current, and this detection means is used for detection of the input current and input voltage according to this aspect. Can do.

  Furthermore, the input voltage value and the input current value are obtained by adding detection values reflecting the temperature and solar radiation intensity at each position of the solar power generation means. Therefore, it is possible to estimate the solar radiation intensity and temperature for the entire photovoltaic power generation means in a form that is more realistic. Since the output performance of the photovoltaic power generation means is diagnosed using the estimated value, more accurate diagnosis can be performed.

  And in the photovoltaic power generation system of the said aspect, the said control part has a voltage lower than the said operating point at least the 1st operating point whose electric current is lower than the said maximum power point, and the said maximum power point in the said diagnosis mode. Move to the second operating point, acquire the open circuit voltage value of the solar power generation means based on the detection value of the detection means at the first operation point, and estimate the temperature of the solar power generation means from the open voltage value And obtaining a short-circuit current value of the solar power generation means based on the detection value of the detection means at the second operating point, and estimating the solar radiation intensity of the solar power generation means from the short-circuit current value. It may be configured.

  According to this configuration, the short-circuit current and the open-circuit voltage are estimated based on the detected values of the input voltage and input current, and the solar radiation intensity and temperature are estimated from the estimated values. Since the estimated values of solar radiation intensity and temperature are used for diagnosis of the output performance of the photovoltaic power generation means, more accurate diagnosis can be performed.

  Furthermore, in the photovoltaic power generation system according to the above aspect, in the diagnosis mode, the control unit moves the first operating point to the open end and directly acquires an open-circuit voltage value by detection of the detection unit, You may be comprised so that the temperature of a photovoltaic power generation means may be estimated from an open circuit voltage value.

  According to this configuration, the open-circuit voltage is directly acquired by moving the first operating point to the open end, so that the output performance of the photovoltaic power generation means can be diagnosed more accurately.

  Further, in the solar power generation system of the above aspect, in the diagnostic mode, the control unit moves the second operating point to the short-circuit end and directly acquires a short-circuit current value by detection of the detection unit, You may be comprised so that the solar radiation intensity of the said photovoltaic power generation means may be estimated from a short circuit current value.

  According to this configuration, since the second operating point is moved to the short-circuit end and the short-circuit current is directly acquired, the output performance of the photovoltaic power generation means can be diagnosed more accurately.

  Furthermore, in the photovoltaic power generation system of the above aspect, the correction maximum power value is corrected based on the line type and length of the wiring connecting the photovoltaic power generation means and the power supply device, and the correction The output performance of the photovoltaic power generation means may be diagnosed based on the corrected maximum power value and the detected value at the maximum power point.

  The input current and input voltage from the solar power generation means are affected by the line type and length of the wiring connecting the solar power generation means and the power supply device. Therefore, as in this aspect, by correcting the corrected maximum power value based on the line type and length of the wiring, the output performance of the solar power generation means can be diagnosed more accurately.

  Moreover, in the solar power generation system according to the above aspect, the solar power generation unit includes a plurality of solar power strings, and the power supply device includes a plurality of converters connected to the solar power strings, An inverter connected to the grid by receiving an output from the converter, and the control unit selects a converter connected to any one of the plurality of solar strings when executing the diagnosis mode The converter connected to the remaining solar strings may be configured to operate in the normal mode while executing the diagnostic mode.

  According to this configuration, even when there is a converter in which the diagnostic mode is executed, other converters are operated in the normal mode, and the inverter is not stopped in the diagnostic mode. For this reason, even when the converter is diagnosed in the diagnostic mode, it is possible to extract power by moving the solar cell to the maximum with the remaining converters.

  In the solar power generation system of the above aspect, the control unit is configured to execute the diagnostic mode every predetermined period, and the corrected maximum power value acquired in each diagnostic mode and the Cumulatively accumulates the detected value at the maximum power point or the power difference between the corrected maximum power value and the detected value at the maximum power point, and based on the accumulation result, the output performance of the photovoltaic power generation means due to deterioration over time You may be comprised so that a fall may be diagnosed.

  According to this configuration, the power value (power difference) is accumulated, and a decrease in output performance due to deterioration with time is diagnosed based on the accumulated data. In the present disclosure, there is an advantage that data necessary for diagnosis of output performance can be reduced, for example, a corrected maximum power value and a detected value at the maximum power point or a difference between them. Therefore, especially when the system has a large number of photovoltaic power generation means, accumulates data over a long period of time (for example, several years to several decades), and looks at the deterioration of the photovoltaic power generation means over time. It can be said that it is suitable.

  In the second aspect of the present invention, a power supply device for converting the output of the solar power generation means, the switch means connected between the output terminals of the solar power generation means, the input current from the solar power generation means, and A detection unit configured to detect an input voltage; and a control unit configured to enable MPPT control to search for a maximum power point by moving an operating point of the solar power generation unit, and the control unit is in a normal mode, While performing the MPPT control, in the diagnosis mode of the photovoltaic power generation means, the operating point is moved larger than that during the MPPT control, and the maximum power point and the detection means at the moved operating point are within a predetermined period. And detecting at least one of solar radiation intensity and temperature of the solar power generation means based on the detected value at the moved operating point, and based on the estimated value The reference maximum power and correction is predetermined Te, diagnosing the output performance of the solar power generation unit based on a detection value of the corrected corrected maximum power value and the maximum power point.

  According to a third aspect of the present invention, there is provided a method for diagnosing the output performance of a solar power generation means, the step of performing MPPT control for operating the solar power generation means at a maximum power point, and detecting the maximum power at the maximum power point. Detecting current at a first operating point having a voltage lower than the maximum power point, estimating solar radiation intensity to the solar power generation means based on the current, and lower current than the maximum power point A step of detecting a voltage at a second operating point and estimating the temperature of the photovoltaic power generation means based on the voltage; and the estimated solar radiation intensity, the estimated temperature, and a predetermined reference maximum power On the basis of the estimated solar radiation intensity and the maximum power performance value at the estimated temperature, and the photovoltaic power generation based on the detected maximum power and the estimated maximum power performance value means And diagnosing the output performance.

  According to the said 2nd and 3rd aspect, the output performance of a photovoltaic power generation means can be diagnosed similarly to the 1st aspect, without using a special measuring device (pyrometer and / or thermometer). Furthermore, since the input voltage value and the input current value are obtained by adding detection values reflecting the temperature and solar radiation intensity at each position of the solar power generation means, the solar radiation intensity and temperature are more realistic. Can be estimated.

  According to the present invention, in order to diagnose the output performance of the solar power generation means based on the detection value from the detection means acquired within a predetermined period, the solar power can be obtained without using a special measuring device such as a solarimeter or a thermometer. The output performance of the photovoltaic power generation means can be diagnosed, and more accurate diagnosis can be realized.

It is the figure which showed the structure of the solar energy power generation system. It is a circuit diagram which shows a non-insulated DC / DC converter. It is a circuit diagram which shows an insulation type DC / DC converter. It is a flowchart which shows operation | movement of a solar power generation system. It is a flowchart which shows operation | movement of a DC / DC converter. It is a flowchart which shows the operation | movement which concerns on the diagnostic mode of a DC / DC converter. It is a figure for demonstrating the diagnostic method of the output performance of a solar power generation means. It is the figure which showed an example of the IV curve of a solar panel. It is the figure which showed the relationship between the installation period of a solar power generation means, and electric power generation amount. It is the enlarged view to which the area | region A of FIG. 9 was expanded.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its scope of application, or its application.

(Configuration of solar power generation system)
Drawing 1 is a figure showing the example of composition of the photovoltaic power generation system concerning an embodiment.

  The photovoltaic power generation system 1 includes a photovoltaic power generation means 2, a power conditioner 3 that converts DC power generated by the photovoltaic power generation means 2 into AC power, and is connected to a distribution line of a commercial power supply system 9, and a management host And a server 10.

  The photovoltaic power generation means 2 includes a plurality of sunlight strings 20. Each solar string 20 includes a plurality of solar panels 21 connected in series. FIG. 1 shows an example in which the photovoltaic power generation means 2 includes three sunlight strings 20. The number of sunlight strings 20 is not limited to three. Moreover, the number of the solar panels 21 which comprise each sunlight string 20 can be set arbitrarily, and the number may differ between each string 20. FIG.

  The power conditioner 3 includes a plurality of DC / DC converters 4, a DC / AC inverter 5, an AC filter circuit 6, an overall control unit 7, and a power supply unit 8.

  The DC / DC converter 4 is provided so as to have a one-to-one correspondence with the solar string 20 and controls the power generation amount of the connected solar string 20. The outputs from the DC / DC converters 4 are added together and input to the DC / AC inverter 5. In the DC / AC inverter 5, DC / AC conversion is performed, and the AC / DC inverter 5 is connected to the distribution line of the commercial power supply system 9 through the AC filter circuit 6.

  The AC filter circuit 6 has a function of removing noise from the output from the DC / AC inverter 5 and preventing disturbance due to environmental factors from the system side. Furthermore, the AC filter circuit 6 includes detection means (not shown) for detecting current and voltage on the system side, so that the overall control unit 7 can grasp voltage, current, and power data on the system side. .

  The overall control unit 7 includes a control unit 44 of each DC / DC converter 4, a communication unit 71 that performs data communication with the management host server 10, and a storage unit 72. Centrally control the operation.

  The power supply unit 8 supplies power to the overall control unit 7 and the drive circuit of the DC / AC inverter 5. The control unit 44 of the DC / DC converter 4 may be operated by receiving power supply from the power supply unit 8, or may be operated using the generated power of the solar string 20.

  The management host server 10 is for monitoring the driving operation of the photovoltaic power generation system 1, and includes a communication unit 11 that performs data communication with the communication unit 71 of the overall control unit 7, and a storage unit 12.

-Configuration of DC / DC converter-
Next, the configuration of the DC / DC converter 4 will be described in detail with reference to FIGS. The DC / DC converter 4 may be either non-insulated or insulated, and FIG. 2 shows a non-insulated circuit example, and FIG. 3 shows an insulated circuit example. 2 and 3, L21 and L31 are inductors, and C21, C22, and C31 to C36 are capacitors. D21, D31, and D32 are diodes, SW22 and SW33 are switching elements, and T31 is a transformer.

  As shown in FIGS. 2 and 3, the DC / DC converter 4 is a chopper type converter configured such that the operating point of the solar string 20 can be changed by the on / off control of the switch unit 41. In the circuit example of FIG. 2, the switch unit 41 is configured by the switching element SW21, and in the circuit example of FIG. 3, the switch unit 41 is configured by the switching elements SW31 and SW32. The switching elements SW21, SW31, and SW32 only have to be configured to be capable of on / off control. For example, transistors such as IGBTs (Insulated Gate Bipolar Transistors) and FETs (Field effect transistors) can be used.

  The DC / DC converter 4 further includes a voltage detection circuit 42 that detects a voltage between the input terminals IN connected to the solar string 20, and one end connected to either one of the input terminals IN. A current detection circuit 43 that measures the input current of the first and second switches, and a control unit 44 that controls on / off of the switch unit 41. The output terminal OUT of the DC / DC converter 4 is connected to the input terminal of the DC / AC inverter 5.

  The control unit 44 includes an MPPT (Maximum Power Point Tracking) unit 44a, a power calculation unit 44b, a diagnosis unit 44c that controls the diagnosis mode, and a communication unit 44d.

  The MPPT unit 44a performs MPPT control for searching for the maximum power point by moving the operating point of the solar string 20 by performing on / off control of the switch unit 41 during the normal mode period. The power calculation unit 44 b calculates a power value based on detection results from the voltage detection circuit 42 and the current detection circuit 43. The communication unit 44d is configured to be capable of data communication with the communication unit 71 of the overall control unit 7. Specifically, the communication unit 44d receives a control instruction such as an operation mode (normal mode / diagnostic mode) from the overall control unit 7. The communication unit 44d transmits the detection value data and calculation data acquired by the voltage detection circuit 42, the current detection circuit 43, and the power calculation unit 44b, error information, an identification number of the own device, and the like to the overall control unit 7.

(Operation of solar power generation system)
Next, operation | movement of the solar power generation system 1 is demonstrated in detail using FIGS.

  In the following description, it is assumed that the sunlight string 20 includes first to third strings 20a, 20b, and 20c, and the DC / DC converters 4 (first to third converters 4a, 4b, 4c) is connected.

  First, when the photovoltaic power generation system 1 starts operation, the first to third converters 4a, 4b, and 4c each operate in the normal mode. That is, MPPT control is performed by each converter 4a, 4b, 4c, and the maximum power is taken out from each string 20a, 20b, 20c.

  Next, when a predetermined condition is satisfied, the overall control unit 7 sequentially controls the control units 44 of the converters 4a, 4b, and 4c so as to operate them in the diagnosis mode. Hereinafter, it will be described in detail with reference to FIG.

  Here, an arbitrary condition can be set as the predetermined condition. For example, even when an instruction from the management host server 10 or an operation (instruction) from an operation unit (not shown) provided outside the power conditioner or an external remote controller (not shown) is received as a predetermined condition. Good. The predetermined condition may be every predetermined period, for example, every week, every day, every hour, or for example, a time specified every day may be set. Furthermore, the predetermined condition may be a combination of a plurality of conditions. For example, in the daily measurement (first condition), when the output of the solar power generation means is 80% or more of the rated output (second condition), the operation is performed in the diagnosis mode. Also good. Also, for example, since there is a possibility of initial failure at the initial stage of installation, the diagnosis mode is executed in a short period (first period) (first condition), and after entering the stable period, it is longer than the first period. The diagnosis mode may be executed every second period (second period) (second condition).

  In S10 of FIG. 4, the overall control unit 7 instructs the first converter 4a to operate in the diagnosis mode. Upon receiving the instruction, the control unit 44 of the first converter 4a temporarily stops the operation in the normal mode, and controls the SW22 in FIG. 2 or the SW33 in FIG. 3 to turn off to shift to a diagnostic mode to be described later. In other words, the control unit 44 switches from the MPPT control by the MPPT unit 44a to the diagnostic control of the output performance of the first string 20a by the diagnosis unit 44c (S11). Further, the control unit 44 controls the SW22 of FIG. 2 or the SW33 of FIG. 3 to be on during the MPPT control, and controls the SW22 of FIG. 2 or the SW33 of FIG. 3 to be off during the diagnosis mode.

  In S11, when the measurement related to the diagnostic mode ends, the control unit 44 of the first converter 4a transmits the detection data to the overall control unit 7 (S12), and returns to the normal mode. That is, the control unit 44 of the first converter 4a starts searching for the maximum power point by the MPPT control again (S13). The overall control unit 7 receives the measurement data transmitted from the control unit 44 of the first converter 4a (S14), analyzes the measurement data, and reports the analysis result to the management host server 10 (S15). For example, if it is found as a result of the above analysis that the first string 20a is abnormal, the management host server 10 is notified of this. The management host server 10 or the manager of the management host server 10 that has received the report performs processing as necessary (for example, arrangement of workers).

  After S14, the overall control unit 7 instructs the second converter 4b to operate in the diagnosis mode (S20). In S20 to S25, the overall control unit 7 and the control unit 44 of the second converter 4b execute the same processing as the flow related to S10 to S15.

  When the diagnosis of the output performance of the second converter 4b is completed, the overall control unit 7 instructs the third converter 4c to operate in the diagnosis mode (S30). And in S30-S35, the process similar to the flow which concerns on S10-S15 is performed in the control part 44 of the overall control part 7 and the 3rd converter 4c.

  Thereafter, the first to third converters 4a, 4b, and 4c operate in the normal mode until the aforementioned predetermined condition is satisfied. If the predetermined condition is satisfied, the flow returns to S10 again, and the overall control unit 7 causes the control unit 44 of each converter 4a, 4b, 4c to operate them in the diagnosis mode. Control sequentially. FIG. 4 shows an example of the case where the above-mentioned predetermined condition is every predetermined period. In this case, for example, the flow returns to S10 after a predetermined period from S34, and the overall control unit 7 again The controller 44 of each converter 4a, 4b, 4c is sequentially controlled so as to operate in the diagnostic mode.

  As described above, the overall control unit 7 causes the control units 44 of the converters 4a, 4b, and 4c to sequentially operate in the diagnosis mode. On the other hand, as shown in FIG. 4, other converters that are not in the diagnostic mode operate in the normal mode (MPPT control), and the output from the converter operating in these normal modes is DC / AC. It is poured from the inverter 5 into the distribution line of the commercial power system. In other words, the photovoltaic power generation system 1 according to the present disclosure can diagnose the output performance of each string in a state where the decrease in output power is minimized without stopping the operation of the system. It has become.

  In the above aspect, the overall control unit 7 analyzes the measurement data. However, the present invention is not limited to this, and the analysis of the measurement data is performed by the management host server 10 or the control unit 44 of each converter 4a, 4b, 4c. You may make it implement. For example, when the measurement data is analyzed by the management host server 10, in S14, S24, S34, the overall control unit 7 directly receives the measurement data received from the control unit 44 of each converter 4a, 4b, 4c to the management host server 10. Send. In this case, the overall control unit 7 may transmit measurement data for each of the converters 4a, 4b, and 4c to the management host server 10 as shown in S15, S25, and S35 of FIG. After receiving the data of all the converters 4a, 4b, and 4c without performing steps S15 and S25 of step 4, the measurement data may be sent collectively in step S35.

  In S14, S24, and S34, the overall control unit 7 transmits an analysis result to the management host server 10 every time data is received from each of the converters 4a, 4b, and 4c (see S15, S25, and S35 in FIG. 4). ), But not limited to this. For example, without performing S15 and S25 in FIG. 4, after the analysis of all the converters 4a, 4b, and 4c is completed, the analysis results may be collectively sent in S35. For example, data for a predetermined period may be held and transmitted to the management host server 10 at once, or when an abnormality occurs, it will be reported immediately, otherwise it will be transmitted collectively for a predetermined period, etc. May be determined according to the priority of data.

-Operation of DC / DC converter-
Next, the operation of the DC / DC converter 4 (4a, 4b, 4c) will be described in detail with reference to FIGS. More specifically, the operation after shifting from the normal mode to the diagnostic mode in S11, S21, and S31 of FIG. 4 will be described in detail. In the following aspect, the first converter 4a will be described as an example, but the same applies to the second and third converters 4b and 4c.

  As shown in FIG. 5, first, the MPPT unit 44a of the first converter 4a performs MPPT control for searching for the maximum power point by moving the operating point of the solar string 20 by performing on / off control of the switch unit 41 (S51). ).

  Then, in S11 of FIG. 4, when receiving an instruction of the diagnostic mode from the overall control unit 7 (YES in S52 of FIG. 5), the first converter 4a executes the diagnostic mode (S53). More specifically, in S53, the control of the control unit 44 is switched from MPPT control by the MPPT unit 44a to diagnostic control of the output performance of the first string 20a by the diagnosis unit 44c, and the flow shown in FIG. 6 is executed.

  First, in S61, the diagnosis unit 44c acquires the maximum power Pdmax at the maximum power point searched by the MPPT unit 44a. Specifically, the power calculation unit 44b calculates the maximum power based on the voltage value and the current value detected by the voltage detection circuit 42 and the current detection circuit 43 at the maximum power point, and the diagnosis unit 44c includes the power calculation unit 44b. The maximum power Pdmax calculated in (1) is acquired. Thereafter, the operating point of the first string 20a is moved to the first operating point P1 (see FIG. 7) near the open end, and the voltage value Vd1 detected by the voltage detection circuit 42 is acquired. Thereafter, in S62, the diagnosis unit 44c moves the operating point of the first string 20a from the first operating point P1 to the second operating point P2 (see FIG. 7) near the short-circuit end, and is detected by the current detection circuit 43. The current value Id2 is acquired. Here, the movement of the operating point in S61 and S62 and the acquisition of the maximum power Pdmax, voltage value Vd1 and current value Id2 at the moving position are performed within a predetermined period. The predetermined period is preferably, for example, a period until the solar radiation amount or temperature changes substantially. The predetermined period is, for example, within 2 seconds, and more preferably within, for example, 0.5 seconds. By determining the predetermined period in this way, each detection value can be acquired in a state where the influence of changes in the amount of solar radiation and temperature is substantially eliminated. As a result, the diagnosis of the output performance of the first string 20a can be performed more accurately.

  Thereafter, the maximum power Pdmax, the voltage value Vd1 and the current value Id2 detected in S61 and S62 are transmitted to the overall control unit 7 via the communication unit 44d. Thereafter, the control unit 44 of the first converter 4a is switched to the operation in the normal mode (S13 in FIG. 4). More specifically, the control of the control unit 44 is switched from the diagnostic control of the output performance by the diagnostic unit 44c to the MPPT control by the MPPT unit 44a.

  In S63, the overall control unit 7 estimates the open circuit voltage Voc1 (see FIG. 7) based on the voltage value Vd1 acquired from the voltage detection circuit 42 at the first operating point P1. The open-circuit voltage Voc1 can be estimated, for example, by using the voltage value Vd1 as it is or by slightly adjusting the detected voltage value Vd1. Near the open end, the change in the detection voltage with respect to the current change in the first string 20a is small. Therefore, even if the open voltage is estimated from the voltage near the open end, an estimated deviation hardly occurs. Also, a plurality of points near the open end are set as the first operating point P1, voltage values are acquired from the voltage detection circuit 42 at the plurality of first operating points, and an approximate line such as an approximate line is obtained from these acquisition results. The open circuit voltage may be estimated by pulling. By using such an approximate line, the open circuit voltage Voc1 can be estimated more accurately. Further, instead of estimating the open circuit voltage Voc1, the first operating point P1 may be moved to the open end, and the open circuit voltage Voc1 may be directly measured by the voltage detection circuit. The open circuit voltage Voc1 can be obtained more accurately by direct measurement.

  When the open circuit voltage Voc1 is estimated (detected) in S63, in S64, the temperature Tc1 of the first string 20a (a solar cell constituting the solar panel 21) based on the following expression (1) using the open circuit voltage Voc1. Element temperature).

Voc1-Voc0 = α × (Tc1-25) Formula (1)
In Expression (1), Voc0 is a predetermined reference voltage, for example, a nominal open circuit voltage. The nominal open circuit voltage is a voltage detected under standard test conditions, and is measured, for example, at an irradiance of 1000 W / m ² (Ee0), an AM (air mass) of 1.5, and a solar cell element temperature of 25 ° C. (Tc0). Voltage. Α is a temperature coefficient of the open circuit voltage of the first string 20a.

  In S65, the overall control unit 7 estimates the short-circuit current Isc1 (see FIG. 7) based on the current value Id2 acquired from the current detection circuit 43 at the second operating point P2. The short-circuit current Isc1 can be estimated, for example, by using the current value Id2 as it is or by slightly adjusting the detected current value Id2. Near the short-circuit end, the change in the detected current with respect to the voltage change of the first string 20a is small. Therefore, even if the short-circuit current is estimated from the current near the short-circuit end, an estimated deviation hardly occurs. Further, a plurality of points near the short-circuit end are set as the second operating point P2, current values are acquired from the current detection circuit 43 at the plurality of second operating points, and an approximate line such as an approximate line is obtained from these acquisition results. The short-circuit current may be estimated by pulling. By using such an approximate line, the short-circuit current Isc1 can be estimated more accurately. Instead of estimating the short-circuit current Isc1, the second operating point P2 may be moved to the short-circuit end, and the current detection circuit 43 may directly measure the short-circuit current Isc1. The short-circuit current Isc1 can be obtained more accurately by direct measurement.

  When the short-circuit current Isc1 is estimated (detected) in S65, in S66, the overall control unit 7 estimates the received solar radiation intensity Ee1 of the first string 20a based on the following equation (2) using the short-circuit current Isc1. To do.

Ee1 = Isc1 / Isc0 × Ee0 Formula (2)
In Formula (2), Isc0 is a predetermined reference current, for example, a nominal short-circuit current. The nominal short-circuit current is, for example, a current detected under the standard test conditions described above. Ee0 is the solar radiation intensity used for standard test conditions.

  In S67, the overall control unit 7 estimates the maximum power value Pmax1 based on the following expression (3) using the estimated values Tc1 and Ee1 of the temperature and the received solar radiation intensity estimated in S64 and S66. The maximum power value Pmax1 is a power value obtained by estimating the output performance of the first string 20a under the measurement conditions according to the diagnostic mode.

Pmax1 = Pmax0 × Ee1 × β × (Tc1-25) Formula (3)
In Equation (3), Pmax0 is a predetermined reference maximum power, for example, the nominal maximum power. The nominal maximum power is, for example, power detected under the standard test conditions described above. Β is a temperature coefficient of output power at the maximum power point of the first string 20a. When Pmax1 is acquired, the flow returns to FIG. 5 and proceeds to S54.

  In S54, the overall control unit 7 (1) compares the estimated maximum power value Pmax1 received from the control unit 44 of the first converter 4a with the measured maximum power value Pdmax, and (2) the estimated maximum power value Pmax1, the short-circuit current. An estimated IV curve is created using the estimated value of Isc1 and the estimated value of open circuit voltage Voc1, and the estimated IV curve is compared with the IV curve under the standard test conditions. Diagnose the output performance of the means.

  More specifically, for example, (1) the estimated maximum power value Pmax1 is compared with the measured maximum power Pdmax, the difference between the absolute values is less than a predetermined power value Ps, and (2) the estimated I− If the shapes of the V curve and the IV curve under the standard test conditions satisfy a predetermined standard (YES in S54), it is determined that the output performance is sufficient, and the flow proceeds to S55. The predetermined reference can be arbitrarily set. For example, whether or not the predetermined criterion is satisfied can be determined based on the fact that the absolute value difference between the estimated IV curve and the IV curve under the standard test conditions is within a predetermined range. it can.

  In S55, the overall control unit 7 transmits normal data, which is predetermined data transmitted in the normal state corresponding to the above (1) and (2), to the management host server 10, and the management host server 10 determines the value. Are stored in the storage unit 12 and accumulated (in FIG. 4, S15, S25, S35). The normal data is not particularly limited as long as it is data capable of grasping (confirming) that the diagnosis result is normal. Normal data includes, for example, (A) estimated maximum power value Pmax1 and measured maximum power value Pdmax or power difference Pdiff (Pdiff = Pmax1-Pdmax), and (B) estimated values Tc1, Ee1 of temperature and received solar radiation intensity, Or the estimated value of the short circuit current Isc1 and the estimated value of the open circuit voltage Voc1. Thereby, in the management host server 10, since the said estimated IV curve can be drawn from the data of said (A) and (B), while being able to reproduce the confirmation with respect to the judgment in the integrated control part 7, The confirmation record can be left. Furthermore, the amount of data to be transmitted can be greatly reduced as compared with the case where the overall control unit 7 sends the IV curve. Moreover, you may make it send the report data to the effect of having diagnosed the output performance of a photovoltaic power generation means in S54 as normal data.

  The normal data may be only the estimated maximum power value Pmax1 and the measured maximum power value Pdmax or the power difference Pdiff described in (A) above. This is because at least the data (A) can be confirmed (determined) on the management host server 10 side that the output performance diagnosis result is correct. Thereby, the transmission data amount can be further reduced.

  Further, the overall control unit 7 may store and accumulate the power values Pmax1, Pdmax, and Pdiff in the storage unit 72 in its own device. Further, the data stored and accumulated in the management host server 10 or the storage unit 72 of the overall control unit 7 may be expanded. For example, the current detection values Id1, Id2 and the voltage detection value Vd1 at the first and second operating points. , Vd2 values, etc. may be stored.

  On the other hand, (3) When the comparison result (absolute value difference) between the maximum power value Pmax1 and the reference maximum power Pmax0 is equal to or greater than the predetermined power value Ps, or (4) the estimated IV curve and the standard test condition When the shape with the IV curve at does not satisfy the predetermined standard (NO in S54), it is determined that the output performance is insufficient, and the flow proceeds to S56. In S56, the overall control unit 7 informs the management host server 10 that the output performance is insufficient (abnormal state), a display unit (not shown) provided in its own device, or an external remote controller (not shown). (Not shown in the figure).

  Further, in S57, the overall control unit 7 transmits abnormal data, which is predetermined data to be transmitted in an abnormal state corresponding to the above condition (3) or (4), to the management host server 10, and the management host server 10 The value is stored in the storage unit 12 and accumulated (in FIG. 4, S15, S25, S35). The data at the time of abnormality is not particularly limited as long as it is data capable of grasping (confirming) that the diagnosis result is an abnormal state. For example, abnormal data includes (B) estimated values Tc1 and Ee1 of temperature and received solar radiation intensity, or estimated value of short circuit current Isc1 and estimated value of open circuit voltage Voc1, (C) maximum power value Pmax1, and (D) Pmax1. The IV curve is acquired at the time of acquisition, or a new IV curve is acquired after S56, and the acquired IV curve data. The management host server 10 stores and accumulates the received maximum power value Pmax1 and the IV curve (S15, S25, S35 in FIG. 4). Further, as described above, the management host server 10 or the administrator of the management host server 10 performs necessary processing (for example, arrangement of workers) according to the abnormal state. At this time, the received IV curve may be analyzed on the management host server 10 side. By analyzing the IV curve, the abnormal state can be analyzed in more detail.

  FIG. 8 shows an example of an acquired IV curve. For example, waveform example 1 shows an example of output shortage due to insufficient solar radiation, etc., and waveform examples 2 and 3 are examples of waveforms when there is an abnormality in the solar panel. As described above, when it is determined that the output performance is insufficient, the IV curve is acquired and analyzed, so that the cause of the insufficient output performance can be grasped in more detail. And then the appropriate response can be selected.

  As described above, according to the present embodiment, the control unit 44 of each converter 4a, 4b, 4c provides detection values at the maximum operating point Pmax, the first operating point P1, and the second operating point P2 within a predetermined period. The integrated control unit 7 is configured to estimate the solar radiation intensity and temperature based on the acquired value, and to diagnose the output performance of each of the strings 20a, 20b, and 20c based on the estimation result. That is, since the solar radiation intensity and temperature can be estimated based on the voltage value and the current value detected at the first operating point P1 and the second operating point P2, a special measuring device such as a solar radiation meter or a thermometer is used. Without fail, the output performance of the solar power generation means can be diagnosed.

  In S54, the output performance of the photovoltaic power generation means is diagnosed based on one of the above conditions (1) or (2), and the normal state (the flow proceeds to S55) or the abnormal state (the flow is (Proceed to S56).

(Other embodiments)
-Diagnosis of degradation of output performance due to aging-
For example, the management host server 10 may be configured to be able to diagnose output performance degradation due to aging. Aged deterioration can be performed based on, for example, data of power values Pmax1, Pdmax, and Pdiff stored in the storage unit 72. Hereinafter, this will be specifically described with reference to FIGS. 9 and 10.

  Here, FIG. 9 is a graph in which Pdiff, which is a power difference between the estimated maximum power value Pmax1 and the measured maximum power value Pdmax, is measured every predetermined period, and the measured values are plotted. FIG. 10 is a graph in which the range A in FIG. 9 is enlarged.

When diagnosing aging degradation, for example, as shown in FIG. 9, a threshold value P _T of Pdiff is determined. For example, when P _diff exceeds this threshold value P _T a plurality of times, It may be determined that the output performance is insufficient (the replacement time is near).

  In this way, by using the accumulated data and attaching conditions such as multiple times in succession, the singular point is affected by the influence of flying objects such as airplanes and birds and the influence of weather (clouds) as shown in FIG. Even when X1 and X2 are generated, the influence can be eliminated as much as possible. As a result, more accurate diagnosis can be made in the diagnosis of aging degradation. In addition, in this aspect, the amount of data required for analysis (data that needs to be stored) is small, and it is necessary for cumulative accumulation of data as compared with the case where IV curves are stored and accumulated for each measurement. There is an advantage that a large amount of storage capacity can be saved.

  Furthermore, the embodiment of the present invention can be modified as follows.

  For example, in the above aspect, in the diagnosis mode, the solar radiation intensity 2 and the temperature of the solar power generation means 2 (each of the strings 20a to 20c) are estimated, but either one may be measured and acquired. .

  More specifically, for example, when measuring the temperature of the solar power generation means 2 using a thermometer, the temperature Tc1 in FIGS. 6 and 7 is obtained directly from the thermometer. In this case, the acquisition of the voltage value Vd1 at the first operating point in S61, and the estimation of the open circuit voltage Vco1 and the temperature Tc1 in S63 and S64 are not performed. In the estimation of Pmax1 in S67, the measured temperature Tc1 is used. Other than that, the output performance of a photovoltaic power generation means can be diagnosed based on the flow similar to the above-mentioned embodiment.

  Similarly, for example, when measuring the solar radiation intensity of the solar power generation means 2 using a solar radiation meter, the solar radiation intensity Ee1 in FIGS. 6 and 7 is obtained directly from the solar radiation meter. In this case, the acquisition of the voltage value Id2 at the second operating point in S62, and the short circuit current Isc1 and the solar radiation intensity Ee1 in S65 and S66 are not estimated. Then, in the estimation of Pmax1 in S67, the measured solar radiation intensity Ee1 is used. Other than that, the output performance of a photovoltaic power generation means can be diagnosed based on the flow similar to the above-mentioned embodiment.

  Further, during the diagnosis mode period (S61 and S62 in FIG. 6), the diagnosis unit 44c sequentially moves the operating point from the maximum power point to the first operating point and the second operating point, thereby increasing the maximum power Pdmax and the voltage value Vd1. The current value Id2 is acquired, but the acquisition order is not limited to this and may be acquired in an arbitrary order. However, it is preferable that these values are acquired within a predetermined period (for example, within 1 second).

  Further, for example, the diagnosis unit 44c acquires an IV curve between the first operating point and the second operating point, and based on the IV curve, the voltage value Vd1 and the maximum power point at the first operating point are obtained. The maximum power Pdmax and the current value Id2 at the second operating point may be acquired. Even in this case, the IV curve is preferably acquired within a predetermined period (for example, within 1 second). Thereby, similarly to the said embodiment, the diagnosis of the output performance of each string 20a, 20b, 20c can be implemented more correctly.

  In addition, the estimation of each value during the diagnosis mode period (S63 to S67 in FIG. 6) is not limited to the order in FIG. For example, the order of S64 and S65 may be switched, and S65 (Isc1 estimation) may be performed before S64 (Tc1 estimation). Further, the flow of S63-S64 and the flow of S65-S66 may be performed independently. More specifically, for example, S63 (estimation of Voc1) and S65 are started at the same time or one of them first, S64 after the end of estimation of S63, and S66 (estimation of Ee1) after the end of estimation of S65. And are performed independently. In that case, S67 (estimation of Pmax1) may be performed after S64 and S66 are completed.

  Moreover, in the control part 44 of each converter 4a, 4b, 4c, although the MPPT part 44a which performs MPPT control, and the diagnostic part 44c which performs diagnostic control were shown in the separate block, the single MPPT part 44a was shown. May perform MPPT control and diagnostic control. Further, although the overall control unit 7 and each control unit 44 of each converter 4a, 4b, 4c have been described as being separate blocks, a part or all of each control unit 44 and the overall control unit 7 is 1 It may be realized by one integrated circuit (for example, a microcomputer), or its function may be integrated into a single control unit.

  Further, a storage unit (not shown) is provided in the control unit 44 of each converter 4a, 4b, 4c, and for example, each converter 4a, 4b, 4c performs the flow of the diagnosis mode according to FIG. You may do it.

  Further, in the diagnosis of the output performance of the photovoltaic power generation means 2 in the diagnostic mode, it is obtained from the formula (3) based on the line type and length of the wiring connecting the photovoltaic power generation means 2 and the power conditioner 3. The maximum power value Pmax1 may be corrected. In that case, in S54, the overall control unit 7 compares the corrected estimated maximum power value Pmax1 with the measured maximum power value Pdmax. In this way, by correcting the estimated maximum power value Pmax1 based on the line type and length of the wiring, it is possible to eliminate the influence of the line type and length of the wiring, and more accurately It becomes possible to diagnose the output performance.

  Since the output performance of the photovoltaic power generation means can be diagnosed more accurately without using a special measuring device such as a pyranometer or thermometer, it is extremely useful as a photovoltaic power generation system having a diagnostic function.

DESCRIPTION OF SYMBOLS 1 Solar power generation system 2 Solar power generation means 3 Power conditioner (power supply device)
4 DC / DC converter (power supply, converter)
5 DC / AC inverter (inverter)
7 General control department (control department)
20 Solar string (photovoltaic power generation means)
21 Solar panels (photovoltaic power generation means)
41 Switch part (switch means)
42 Voltage detection circuit (detection means)
43 Current detection circuit (detection means)
44 Control unit

Claims (9)

A solar power generation system comprising a solar power generation means, a power supply device that converts the output of the solar power generation means, and a control unit that controls the power supply device,
The power supply device includes switch means provided between output terminals of the solar power generation means, and detection means for detecting an input current and an input voltage from the solar power generation means,
The controller is
In normal mode, while performing the MPPT (Maximum Power Point Tracking) control to search the maximum power point by moving the operating point of the photovoltaic power generation means by on-off control of the switch means,
In the diagnostic mode of the solar power generation means, the operating point is moved larger than at the time of the MPPT control, and detection values from the detection means at the maximum power point and the moved operating point are acquired within a predetermined period. , Estimating at least one of solar radiation intensity and temperature of the photovoltaic power generation means based on the detected value at the moved operating point, correcting a predetermined reference maximum power based on the estimated value, A photovoltaic power generation system, wherein the output performance of the photovoltaic power generation means is diagnosed based on the corrected maximum corrected power value and the detected value at the maximum power point. The solar power generation system according to claim 1,
In the diagnostic mode, the control unit moves the operating point to at least a first operating point having a current lower than the maximum power point and a second operating point having a voltage lower than the maximum power point. An open circuit voltage value of the photovoltaic power generation means is obtained based on a detection value of the detection means at an operating point, a temperature of the solar power generation means is estimated from the open circuit voltage value, and the detection at the second operating point is performed. A solar power generation system characterized in that a short-circuit current value of the solar power generation means is acquired based on a detection value of the means, and the solar radiation intensity of the solar power generation means is estimated from the short-circuit current value. The solar power generation system according to claim 2,
In the diagnosis mode, the control unit
The first operating point is moved to the open end, the open voltage value is directly acquired by detection of the detection means, and the temperature of the solar power generation means is estimated from the open voltage value. Power generation system. The photovoltaic power generation system according to claim 2 or 3,
In the diagnosis mode, the control unit
The second operating point is moved to the short-circuit end, the short-circuit current value is directly acquired by detection of the detection means, and the solar radiation intensity of the solar power generation means is estimated from the short-circuit current value Photovoltaic system. In the solar power generation system according to any one of claims 1 to 4,
The corrected maximum power value is corrected based on the line type and length of the wiring connecting the photovoltaic power generation means and the power supply device, and the corrected corrected maximum power value and the maximum power point are corrected. A photovoltaic power generation system characterized by diagnosing the output performance of the photovoltaic power generation means based on a detected value. The solar power generation system according to claim 1,
The photovoltaic power generation means has a plurality of sunlight strings,
The power supply device includes a plurality of converters connected to correspond to the solar strings, and an inverter that receives an output from each converter and is linked to a system.
The control unit, when executing the diagnostic mode,
A converter connected to any one of the plurality of solar strings is selected to execute a diagnostic mode, while converters connected to the remaining solar strings are operated in a normal mode. Solar power system. The solar power generation system according to claim 1,
The controller is
It is configured to execute the diagnostic mode every predetermined period,
Accumulated accumulation of the corrected maximum power value and the detected value at the maximum power point or the power difference between the corrected maximum power value and the detected value at the maximum power point acquired in each diagnosis mode, and the accumulation result Based on the above, a solar power generation system characterized by diagnosing a decrease in output performance due to deterioration with time of the solar power generation means. A power supply device for converting the output of the solar power generation means,
Switch means connected between output terminals of the solar power generation means;
Detection means for detecting an input current and an input voltage from the solar power generation means;
A control unit configured to be capable of MPPT control for searching for the maximum power point by moving the operating point of the solar power generation means,
The controller is
In normal mode, while performing MPPT control,
In the diagnostic mode of the solar power generation means, the operating point is moved larger than at the time of the MPPT control, and detection values from the detection means at the maximum power point and the moved operating point are acquired within a predetermined period. , Estimating at least one of solar radiation intensity and temperature of the photovoltaic power generation means based on the detected value at the moved operating point, correcting a predetermined reference maximum power based on the estimated value, A power supply apparatus characterized by diagnosing the output performance of the photovoltaic power generation means based on the corrected maximum corrected power value and the detected value at the maximum power point. A diagnostic method for diagnosing the output performance of solar power generation means,
Performing MPPT control for operating the solar power generation means at a maximum power point;
Detecting a maximum power at the maximum power point;
Detecting a current at a first operating point having a voltage lower than the maximum power point, and estimating a solar radiation intensity to the solar power generation means based on the current;
Detecting a voltage at a second operating point having a current lower than the maximum power point, and estimating the temperature of the photovoltaic power generation means based on the voltage;
Estimating a performance value of the estimated solar radiation intensity and the maximum power at the estimated temperature based on the estimated solar radiation intensity, the estimated temperature and a predetermined reference maximum power;
Diagnosing the output performance of the photovoltaic power generation means based on the detected maximum power and the performance value of the estimated maximum power.

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