Abstract:
A data collection device for photovoltaic power generation is provided. The data collection device for collecting photovoltaic power generation data includes a reception unit receiving, from a photovoltaic device, generation that absorbed solar energy is converted into electrical energy, and photovoltaic power generation related information; a storage unit storing the photovoltaic power generation related information on the photovoltaic device; a control unit determining a predicted life of the photovoltaic device based on the photovoltaic power generation related information received from the reception unit and accumulated related information stored in the storage unit; and a transceiver transmitting a result of determination to an external device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Pursuant to 35 U.S.C. §119(a), this application claims the benefit of earlier filing date and right of priority to Korean Patent Application No. 10-2015-0020929, filed on Feb. 11, 2015 the contents of which are hereby incorporated by reference herein in its entirety. 
       BACKGROUND 
       [0002]    The present disclosure relates to a photovoltaic system, and more particularly to, a data collection device that predicts the life of a photovoltaic device and notifies an inspection cycle. 
         [0003]    Due to worries about the exhaustion of fossil energy, such as oil and environmental pollution, interest in alternative energy increases. Among others, photovoltaic power generation that uses solar energy to produce electricity on a large scale by spreading, on a large scale, panels to which solar batteries are attached. The photovoltaic power generation has advantages in that there is no need to consume fuel costs and there is no air pollution or waste, because it uses unlimited, pollution-free solar energy. 
         [0004]    A solar energy power generation style includes an independent style and a system-associated style. In the system-associated style, a photovoltaic device is connected to a typical power system. When a photovoltaic system generates electricity in daytime, it transmits power and at night or when it rains, the photovoltaic power generation system receives electricity from a system. In order to efficiently use the system-associated photovoltaic system, a photovoltaic system has been introduced which stores idle power in a battery energy storage system (BESS) under a light load, and discharges the BESS to supply discharged power as well as photovoltaic power to the system under a heavy load. 
       SUMMARY 
       [0005]    Embodiments apply accumulated failure data to predict the life of a product based on use history information on a photovoltaic device. Embodiments also provide a photovoltaic system that notifies an inspection cycle for the photovoltaic device or recommends replacement according to a prediction result. 
         [0006]    In one embodiment, a data collection device for collecting photovoltaic power generation data includes a reception unit receiving, from a photovoltaic device, generation that absorbed solar energy is converted into electrical energy, and photovoltaic power generation related information; a storage unit storing the photovoltaic power generation related information on the photovoltaic device; a control unit determining a predicted life of the photovoltaic device based on the photovoltaic power generation related information received from the reception unit and accumulated related information stored in the storage unit; and a transceiver transmitting a result of determination to an external device. 
         [0007]    The photovoltaic power generation related information may include at least one of a use period, failure history, accumulated generation, weather information, and installation position of the photovoltaic device. 
         [0008]    The control unit determines a failure probability at regular intervals based on the photovoltaic power generation related information and determines, as a predicted life, a period in which the determined failure probability is highest. 
         [0009]    The reception unit may receive, from the external device, a generation control signal and inspection cycle information for the photovoltaic device. 
         [0010]    The control unit may transmit, to the photovoltaic device and the external device, a control signal to stop an operation of the photovoltaic device based on the determined predicted life. 
         [0011]    The data collection device may further include a display unit that displays a response received from the external device. 
         [0012]    In another embodiment, a photovoltaic system using solar energy includes a photovoltaic device absorbing and converting solar energy into electrical energy; and a data collection device receiving, from the photovoltaic device, photovoltaic power generation and photovoltaic power generation related information, storing the photovoltaic power generation related information on the photovoltaic device, and determining a predicted life of the photovoltaic device based on the photovoltaic power generation related information received from a reception unit and accumulated related information stored in the storage unit. 
         [0013]    The photovoltaic system may further include an external device that transmits, to the data collection device, a generation control signal and inspection cycle information for the photovoltaic device based on the predicted life of the photovoltaic device that is received from the data collection device. 
         [0014]    The external device may transmit a control signal to lower generation to the data collection device when the predicted life is shorter than an average life of the photovoltaic device of a same model. 
         [0015]    The data collection device may transmit, to the photovoltaic device and the external device, a control signal to stop an operation of the photovoltaic device based on the determined predicted life. 
         [0016]    The data collection device may output a response received from the external device. 
         [0017]    The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a block diagram of a system-associated photovoltaic device according to an embodiment. 
           [0019]      FIG. 2  is a block diagram of a small-scale system-associated photovoltaic device according to an embodiment. 
           [0020]      FIG. 3  is a flowchart of the operation of a system-associated photovoltaic device according to an embodiment. 
           [0021]      FIG. 4  is a block diagram that represents the configuration of a photovoltaic system. 
           [0022]      FIG. 5  is a block diagram that represents the configuration of a data collection device. 
           [0023]      FIG. 6  is a flow chart of a failure inspection method of a photovoltaic system according to an embodiment. 
           [0024]      FIGS. 7 a  and 7 b    are diagrams that represent an embodiment predicting the life of a product from factors that predict the life of the product. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0025]    Embodiments are described below in detail with reference to the accompanying drawings so that a person skilled in the art may easily practice the embodiments. However, the present disclosure may be implemented in many different forms and is not limited to embodiments that are described herein. In addition, parts irrelevant to descriptions are not provided in the drawings in order to make the present disclosure clear and similar parts throughout the disclosure have similar reference numerals. 
         [0026]    Also, when it is described that a part includes some components, it should be understood that it may not exclude but further include other components if there is no specific objection. 
         [0027]    In the following, a system-associated photovoltaic device according to an embodiment is described with reference to  FIGS. 1 to 3 . 
         [0028]      FIG. 1  is a block diagram of a system-associated photovoltaic device according to an embodiment. 
         [0029]    A system-associated photovoltaic device  100  according to an embodiment includes a solar battery array  101 , an inverter  103 , an alternating current (AC) filter  105 , an AC/AC converter  107 , a system  109 , a charging control unit  111 , a battery energy storage system  113 , and a system control unit  115 . 
         [0030]    The solar battery array  101  is obtained by coupling a plurality of solar battery modules. The solar battery module is a device in which a plurality of solar batteries is connected in series or parallel to convert solar energy into electrical energy to generate a certain voltage and current. Thus, the solar battery array  101  absorbs solar energy to convert it into electrical energy. 
         [0031]    The inverter  103  inverts direct current (DC) power into AC power. It receives the DC power supplied by the solar battery array  101  or the DC power discharged by the battery energy storage system  113  through the charging control unit  111  to invert them into AC power. 
         [0032]    The AC filter  105  filters the noise of power inverted into the AC power. 
         [0033]    The AC/AC converter  107  converts the size of a voltage of the AC power devoid of noise, and supplies the converted power to the system  109 . 
         [0034]    The system  109  is a system that incorporates many power stations, substations, power transmission and distribution cables, and loads to generate and use power. 
         [0035]    The charging control unit  111  controls the charging and discharging of the battery energy storage system  113 . When the system is a heavy load, the charging control unit  111  receives power from the battery energy storage system  113  and delivers it to the system. When the system is a light load, the charging control unit  111  receives power from the solar battery array  101  and delivers it to the battery energy storage system  113 . 
         [0036]    The battery energy storage system  113  receives electrical energy from the solar battery array  101  for charging and discharges the charged electrical energy according to the power supply and demand condition of the system  109 . In particular, in the case that the system  109  is a light load, the battery energy storage system  113  receives idle power from the solar battery array  101  for charging. When the system  109  is a heavy load, the battery energy storage system  113  discharges charged power to supply power to the system  109 . The power supply and demand condition of the system has a big difference according to the time zone. Thus, it is inefficient that the system-associated photovoltaic device  100  uniformly supplies the power supplied by the solar battery array  101  without consideration of the power supply and demand condition of the system  109 . Therefore, the system-associated photovoltaic device  100  uses the battery energy storage system  113  to adjust an amount of power supply according to the power supply and demand of the system  109 . Accordingly, the system-associated photovoltaic device  100  may efficiently supply power to the system  109 . 
         [0037]    The system control unit  115  controls the operations of the charging control unit  111 , the inverter  103 , the AC filter  105 , and the AC/AC converter  107 . 
         [0038]      FIG. 2  is a block diagram of a small-capacity system-associated photovoltaic device according to an embodiment. 
         [0039]    A small-capacity system-associated photovoltaic device  200  according to an embodiment includes a solar battery array  101 , an inverter  103 , an AC filter  105 , an AC/AC converter  107 , a system  109 , a charging control unit  111 , a battery energy storage system  113 , a system control unit  115 , and a DC/DC converter  117 . 
         [0040]    The present embodiment is the same as the embodiment in  FIG. 1  but further includes the DC/DC converter  117 . The DC/DC converter  117  converts the voltage of DC power generated by the solar battery array  101 . The voltage of power produced by the solar battery array  101  in the small-capacity system-associated photovoltaic device  200  is low. Thus, there is a need to boost the voltage in order to input power supplied by the solar battery array  101  to the inverter. The DC/DC converter  117  converts the voltage of power produced by the solar battery array  101  into a voltage that may be input to the inverter  103 . 
         [0041]      FIG. 3  is a flowchart of the operation of a system-associated photovoltaic device according to an embodiment. 
         [0042]    The solar battery array  101  converts solar energy into electrical energy in step S 101 . 
         [0043]    The system control unit  115  determines whether there is a need to supply power to the system  109 , in step S 103 . Whether there is a need to supply power to the system  109  may be determined based on whether the system  109  is a heavy load or light load. 
         [0044]    When there is no need to supply power to the system  109 , the system control unit  115  controls the charging control unit  111  to charge the battery energy storage system  113 , in step S 105 . In particular, the system control unit  115  may generate a control signal that controls the charging control unit  111 . The charging control unit  111  may receive the control signal to charge the battery energy storage system  113 . 
         [0045]    The system control unit  115  determines whether there is a need to discharge the battery energy storage system  113 , in step S 107 . It is possible to determine whether there is a need to discharge the battery energy storage system  113  because electrical energy supplied by the solar battery array  101  fails to satisfy the power demand of the system  109 . Also, the system control unit  115  may determine whether the battery energy storage system  113  stores sufficient electrical energy to be discharged. 
         [0046]    When there is a need to discharge the battery energy storage system  113 , the system control unit  115  controls the charging control unit  111  to discharge the battery energy storage system  113 , in step S 109 . In particular, the system control unit  115  may generate a control signal that controls the charging control unit  111 . The charging control unit  111  may receive the control signal to discharge the battery energy storage system  113 . 
         [0047]    The inverter  103  inverts electrical energy discharged by the battery energy storage system  113  and electrical energy converted by the solar battery array  101  into AC, in step S 111 . In this case, the system-associated photovoltaic device  100  inverts both the electrical energy discharged by the battery energy storage system  113  and the electrical energy converted by the solar battery array  101  through a single inverter  103 . Each electric appliance has a limit in consumption power. The limit includes an instantaneous limit and a long-term limit, and maximum power that may be used without damage to a device for a long time is defined as rated power. In order to maximize the efficiency of the inverter  103 , there is a need to supply power so that the battery energy storage system  113  and the solar battery array  101  use power corresponding to 40% to 60% of the rated power. 
         [0048]    The AC filter  105  filters the noise of inverted power, in step S 113 . 
         [0049]    The AC/AC converter  107  converts the size of a voltage of the filtered AC power to supply the converted power to the system  109 , in step S 115 . 
         [0050]    The system-associated photovoltaic device  100  supplies converted power to the system in step S 117 . 
         [0051]    Since the system-associated photovoltaic device  100  according to the embodiments in  FIGS. 1 to 3  uses only a single inverter  103 , there are following limitations when the rated power of the inverter  103  is determined based on the capacity of the solar battery array  101  in order to design the system-associated photovoltaic device  100 . When the battery energy storage system  113  discharges electricity and thus supplies electrical energy along with the solar battery array  101 , it is difficult to maximize the efficiency of the inverter  103  because the inverter  103  uses power exceeding 40% to 60% of the rated power. Alternatively, when the battery energy storage system  113  discharges electricity and thus supplies electrical energy solely, it is difficult to maximize the efficiency of the inverter  103  because the inverter  103  uses power less than 40% to 60% of the rated power. Besides, when the battery energy storage system  101  supplies a little amount of electrical energy, it is difficult to maximize the efficiency of the inverter  103  because the inverter  103  uses power less than 40% to 60% of the rated power. In this case, the efficiency with which the system-associated photovoltaic device  100  converts solar energy into electrical energy decreases. Also, since the total harmonic distortion (THD) of power increases, the quality of power that the system-associated photovoltaic device  100  produces goes down. 
         [0052]      FIG. 4  is a block diagram that represents the configuration of the photovoltaic system  1 . 
         [0053]    Referring to  FIG. 4 , a solar inverter  103  may be included in the photovoltaic device  100 . Since the solar inverter  103  has been described above in detail, related descriptions are omitted in  FIG. 4 . The solar inverter  103  may exist in singularity or in plurality in the photovoltaic device  100 . The photovoltaic inverter  103  may deliver an amount of photovoltaic power generation to a data collection device  300 . 
         [0054]    Various sensors of the photovoltaic device  100  may deliver sensed data along with the amount of photovoltaic power generation to the data collection device  300 . In an embodiment, the sensed data may include at least one of sunshine, temperature, sunrise/sunset time, and a weather condition. The photovoltaic device may deliver power generation time information along with the above-described data to the data collection device  300 . 
         [0055]    The data collection device  300  receives and synthesizes data from the lower inverter  103  and the photovoltaic device  100 . The data collection device  300  may be a component in the photovoltaic device  100  or may be a separate component that is connected to a plurality of photovoltaic devices  100 . The data collection device  300  may provide the collected power generation information to users or clients for monitoring. Also, when there is a higher server  400  connected to the plurality of data collection devices  300 , it is possible to deliver the collected power generation information to the higher server  400 . 
         [0056]    In the following, the data collection device  300  is described in detail with reference to  FIG. 5 . 
         [0057]    The data collection device  300  may include a control unit  315 , a transceiver  316 , a storage unit  317 , and a display unit  318 , as shown in  FIG. 5 . However, the embodiment is not limited to components in  FIG. 5  and may further include other components as needed. 
         [0058]    The transceiver  316  receives photovoltaic related data from the photovoltaic device  100  that includes the inverter  103  and various sensors (not shown). A reception method may include both wired and wireless communication methods. When the data collection device  300  is a component in the photovoltaic device  100 , it is possible to receive data through a circuit that is connected to between internal components. 
         [0059]    Also, the transceiver  316  may transmit the collected photovoltaic power generation data to the higher server  400 . Likewise, it is possible to transmit the data to the higher server  400  through wired/wireless communication. 
         [0060]    Also, the transceiver  316  may transmit the amount of photovoltaic power generation to users and clients. In particular, it is possible to transmit information for monitoring the amount of power generation to the owner of the photovoltaic device  100  or to an electricity dealer. 
         [0061]    Also, the transceiver  316  may also be divided into a transceiver and a receiver. 
         [0062]    The storage unit  317  stores collected power generation data. Photovoltaic power generation is performed everyday, and the data collected by the data collection device  300  is stored in the storage unit  317  for the time being and transmitted to another place. The data stored in the storage unit  317  may be utilized for decreasing transmission data to be described below. 
         [0063]    The display unit  318  may display data for monitoring the amount of photovoltaic power generation. The display unit may include a display that visually displays data, and a speaker that auditorily outputs data. 
         [0064]    The control unit  315  controls the operations of the above-described transceiver  316 , storage unit  317 , and display unit  318 . Furthermore, the control unit  315  may process the received data to generate difference data. How to process the data is described below in detail. 
         [0065]      FIG. 6  is a flow chart of a failure inspection method of a photovoltaic system according to an embodiment. 
         [0066]    The photovoltaic device  100  transmits photovoltaic power generation information to the data collection device  300  in step S 301 . In particular, an amount of photovoltaic power generation collected by the solar inverter  103  in the photovoltaic device  100  and other power generation information collected by various sensors are transmitted to the data collection device  300 . 
         [0067]    In an embodiment, the collected power generation information may include the use period of a corresponding photovoltaic device, generation information, and the failure history of the corresponding photovoltaic device until now. 
         [0068]    In another embodiment, the collected power generation information may include whether weather is extreme and weather information. In this case, the weather information may include e.g., temperature, humidity, and information on the region in which the corresponding photovoltaic device is installed. 
         [0069]    The information delivered to the data collection device  300  may also be information collected by the photovoltaic device  100  or information input upon the initial installation of the device. For example, the information on the region in which the photovoltaic device  100  is installed may be data input upon upon the installation of the photovoltaic device. 
         [0070]    When the transceiver  316  of the data collection device  300  receives power generation information from the photovoltaic device, the control unit  315  of the data collection device calls accumulated date related to a corresponding photovoltaic device from the storage unit  317  in step S 303 . Use data on the same device as the photovoltaic device that provides power generation information and a photovoltaic device of a different model is stored in the storage unit  317  of the data collection device  300 . Thus, the control unit  315  calls related data from the storage unit  317  in order to compare the past use details of the same device with the currently received data. 
         [0071]    The data stored in the storage unit  317  may include the average life and normal generation of corresponding photovoltaic devices, state data on a photovoltaic device that has experienced an exceptional situation, or the like. The exceptional situation may include a case where the photovoltaic device has met typhoon or heavy rain, for example. 
         [0072]    The control unit  315  compares the data received from the photovoltaic device  100  with the data called from the storage unit  317  to predict the life of the corresponding photovoltaic device  100  in step S 305 . In particular, it compares data on the current photovoltaic device  100  with accumulated data on the photovoltaic device  100  of the same model to predict life. 
         [0073]    In an embodiment, the control unit  315  may predict the life from the use period of the photovoltaic device  100 . For example, in the case that data accumulated with respect to the average life of the same model as the corresponding device indicates 10 years and the use period received from the photovoltaic device  100  is 9 years, the control unit  315  may determine that the photovoltaic device  100  has a limited life. 
         [0074]    As another example, in the case that there is no problem in use period but the received generation data is  100  and the average generation data of the same model as a corresponding photovoltaic device is  200 , it is possible to predict that the corresponding photovoltaic device has a limited life, because the corresponding photovoltaic device  100  has a problem. 
         [0075]    As another example, in the case that data that the number of times that the corresponding photovoltaic device  100  has been inspected in recent years due to failure is equal to or larger than a specific number is received, the control unit  315  may predict the life of a device from average life data when the device of the same model stored in the storage unit  317  is inspected a corresponding number of times. 
         [0076]    As another example, in the case that the corresponding photovoltaic device  100  meets extreme weather (e.g., typhoon, heavy rain), the control unit  315  may predict the life of the photovoltaic device  100  from average life data when the device of the same model stored in the storage unit  317  meets the received extreme weather. In particular, in the case that there is accumulated data that when the photovoltaic device suffers flooding damage due to heavy rain, almost all of photovoltaic devices need inspection and when the inspection is not performed, their operations stop within six months, it is possible to predict the remaining life and state of the corresponding photovoltaic device  100  as in the accumulated data. 
         [0077]    As another example, in the case that data that the temperature of a region where the corresponding photovoltaic device  100  is installed is equal to or higher than a specific number, the control unit  315  may predict the life of the corresponding photovoltaic device  100  from the average life of photovoltaic devices installed at the specific number from the storage unit. 
         [0078]    The control unit  315  may together consider factors that may predict the above-described device life, to predict the life of a product. Corresponding content is described below in more detail with reference to  FIG. 7 . 
         [0079]      FIGS. 7 a  and 7 b    are diagrams that represent an embodiment predicting the life of a product from factors that predict the life of the product. 
         [0080]    Referring to  FIG. 7 a   , a product use period, a failure history, extreme weather, and weather information are represented on the horizontal axis of a table as a criterion for predicting the life of a device, and a failure probability by criterion is represented on the vertical axis of the table. Specifically, if the product use period or accumulated generation data has a difference equal to or larger than a specific value from normal data or approaches an average failure period, a probability that a corresponding photovoltaic device fails after one year is 20%, a probability that a corresponding photovoltaic device fails after two years is 70%, and a probability that a corresponding photovoltaic device fails after three years is 70%. Thus, when only the product use period or accumulated generation is considered, it may be predicted that a corresponding device is most likely to fail after three years and thus the control unit  315  may determine that the remaining life is three years. 
         [0081]    According to the content of the table in  FIG. 7 a   , when four factors are considered, it is possible to see that a probability that the corresponding photovoltaic device  100  fails after one year is 25%, a probability that the corresponding photovoltaic device fails after two years is 45%, a probability that the corresponding photovoltaic device fails after three years is 80%, a probability that the corresponding photovoltaic device fails after four years is 48%, and a probability that the corresponding photovoltaic device fails after five years is 38%. Thus, a corresponding graph is shown in  FIG. 7 b    and the control unit  315  may determine based on data received from the corresponding photovoltaic device that the predicted life is three years. 
         [0082]    In other words, the control unit  315  may determine the failure probability of a photovoltaic device at regular intervals based on additional information on photovoltaic power generation and it is possible to determine, as the predicted life, a period in which the determined failure probability is the highest. In this case, the regular interval may be one year. Also, a user may arbitrarily determine the regular interval. 
         [0083]    In addition, since the probability that the device fails after three years is the highest, the control unit  315  may also determine that the corresponding photovoltaic device  100  needs regular inspection within three years. 
         [0084]    Also, the control unit  315  may assign weight to factors predicting the life of the photovoltaic device  100  to enhance the accuracy of life prediction. In the case that e.g., accumulated data is referenced and the control unit  315  determines that life prediction based on a failure history is most accurate, it is possible to determine that the corresponding photovoltaic device has a limited life, though other data excluding data on the failure history is normal. 
         [0085]    Also, in the case that the control unit  315  predicts the life of the photovoltaic device  100  and determines that it is difficult to operate the corresponding photovoltaic device  100  longer, it is also possible to transmit a control signal to store the operation of the device to the photovoltaic device  100 . In this case, the control unit  315  may notify a higher server that a corresponding control signal has been transmitted. 
         [0086]    The data collection device  300  delivers predicted life information and photovoltaic power generation data to the higher server  400  through the transceiver  316  in step S 307 . The data collection device  300  may transmit the data to the higher server  400  by using both wired and wireless communication. 
         [0087]    The higher server  400  synthesizes the predicted life information and related generation information received from the data collection device  300  to generate a device inspection signal in step S 309 . In an embodiment, the device inspection signal may be information on a cycle in which a corresponding photovoltaic device is inspected. In another embodiment, the device inspection signal may be a control signal that lowers generation based on life information on a corresponding photovoltaic device. In particular, in the case that the predicted life is lower than the average life of a photovoltaic device of the same model, the higher server  400  may generate a control signal that lowers generation. 
         [0088]    In another embodiment, the device inspection signal may also include content that changes the installation position of a corresponding photovoltaic device. In another embodiment, it is also possible to generate message content that prepares for the photovoltaic device  100  based on weather information. 
         [0089]    The data collection device  300  receives control signals transmitted by the higher server  400  in step S 311 . In particular, the data collection device  300  may receive control signals from the higher server  400  through the receiver  316 . Additionally, the data collection device  300  may also perform, through the control unit  315 , an operation corresponding to the control signal received from the higher server  400 , and may also notify an administrator of message content when corresponding message content is received. 
         [0090]    It is possible to predict the life of a photovoltaic device based on photovoltaic power generation data and prepare before serious failure occurs. 
         [0091]    Also, by preparation, it is possible to minimize a photovoltaic power generation vacuum due to large-scale device failure. 
         [0092]    Also, even when an administrator does not regularly inspect the photovoltaic device, it is possible to predict the state of the device and thus it is easy to manage the device. 
         [0093]    The characteristics, structures, and effects described in the embodiments above are included in at least one embodiment but are not limited to one embodiment. Furthermore, the characteristic, structure, and effect illustrated in each embodiment may be combined or modified for other embodiments by a person skilled in the art. Thus, it would be construed that contents related to such a combination and such a variation are included in the scope of embodiments. 
         [0094]    Embodiments are mostly described above. However, they are only examples and do not limit the present disclosure. A person skilled in the art may appreciate that many variations and applications not presented above may be implemented without departing from the essential characteristic of embodiments. For example, each component particularly represented in embodiments may vary. In addition, it should be construed that differences related to such a variation and such an application are included in the scope of the present disclosure defined in the following claims.