Patent Publication Number: US-2019190268-A1

Title: Power supply monitoring data processing device, power supply monitoring data processing method, and power supply monitoring data processing program

Description:
TECHNICAL FIELD 
     The present invention relates to a power source monitoring data processing device, a power source monitoring data processing method, and a power source monitoring data processing program, all of which are intended to process monitoring data of a power source system equipped with a backup power storage device. 
     BACKGROUND ART 
     Electric power conditions in developing countries, including India, Southeast Asian courtiers, and African courtiers, are worse than those in developed countries, including Japan and European countries. Therefore, electric power is often cut off. Power failures in such developing countries happen usually accidentally but sometimes in a planned way. Thus, as a rule, infrastructure installations, such as cellular phone base stations, need to have backup power source systems, which are used upon power failures in system power sources. To provide quality communication services for developing countries, stable facility control for communication facilities and secured power sources are an important key. 
     In many cases, hybrid systems in which a power generation device and a storage battery collaborate with each other are used as backup power source systems. This power generation device can be a solar or wind power generation device. However, the power generation device is usually an internal combustion power generation device (for example, a diesel generator or a gas turbine generator) that can generate electric power independently of weather (for example, see PTLs 1 and 2). If an internal combustion power generation device is used, fossil fuel is needed. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Unexamined Japanese Patent Publication No. 2004-062254 
     PTL 2: Unexamined Japanese Patent Publication No. 2016-039648 
     SUMMARY OF THE INVENTION 
     When a power failure occurs in a system power source, a backup power source system causes both a storage battery and an internal combustion power generation device to supply a backup power source to a load. In this case, if the power source is not controlled in accordance with stability of the system power source, the internal combustion power generation device may inevitably operate for an unexpectedly long time. As a result, excessive amounts of fuel might be consumed. Many backup power source systems used in developing countries may fail to permit checking of present settings and environment, thus making verification of a fuel consumption difficult. 
     The present invention deals with the above situation with an object of providing a technique for continuously and efficiently operating a power source system in which a power storage device and an internal combustion power generation device collaborate with each other. 
     According to an aspect of the present invention which achieves the above object, a power source monitoring data processing device includes: a data acquisition section that acquires first data and second data as monitoring data of a power source system, the power source system including a switching section that selectively outputs alternating current (AC) power supplied from a system power source or an internal combustion power generation device, an alternating current/direct current (AC/DC) converter that converts the AC power output from the switching section into direct current (DC) power and outputs the DC power to a DC load, and a power storage device connected to a DC bus between the AC/DC converter and the DC load, the first data containing an output voltage and/or an output current of the switching section, the second data containing an output voltage and/or an output current of the power source system; and a data processor that estimates an operational state of the internal combustion power generation device, based on the first data and the second data acquired by the data acquisition section and that generates a modification plan for a system configuration and/or a discharge lower limit of the power storage device to shorten an operational time of the internal combustion power generation device. 
     Any desired combinations of the above-described components and converted expressions of the present invention in methods, devices, systems, and other similar entities are still effective as aspects of the present invention. 
     The present invention achieves a continuous and efficient operation of a power source system in which a power storage device and an internal combustion power generation device collaborate with each other. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of an overall configuration of communication facilities, a central monitoring system, and a power source monitoring data processing device. 
         FIG. 2  illustrates an example of a configuration of a power source system in a communication facility. 
         FIG. 3  illustrates an example of a time transition of a state of a power source in a certain power source system. 
         FIG. 4  illustrates an example of a configuration of the power source monitoring data processing device according to an exemplary embodiment of the present invention. 
         FIG. 5  is a flowchart of an example of an operation of the power source monitoring data processing device according to the exemplary embodiment of the present invention. 
         FIG. 6  illustrates an example of a format of a fuel reduction performance evaluation report. 
         FIGS. 7 ( a ) and ( b )  each illustrate a modification of a graph area in which an operation result and an estimated operation performed before improvement are shown in  FIG. 6 . 
     
    
    
     DESCRIPTION OF EMBODIMENT 
       FIG. 1  illustrates a block diagram of an overall configuration of communication facilities  1 , central monitoring system  2 , and power source monitoring data processing device  3 . Each communication facility  1  has power source system  10 . The following description gives an example in which each communication facility  1  serves as a base station device for cellular phones. 
     Base station devices for cellular phones installed at many more sites provide higher communication quality. In some vast nations, base station devices are installed at 100,000 or more sites. 
     Central monitoring system  2  is a system that remotely monitors power source systems  10  in the plurality of communication facilities  1 . For example, central monitoring system  2  may include a plurality of servers. Central monitoring system  2  is connected to power source systems  10  in communication facilities  1  over a network and collects monitoring data from power source systems  10 . The network may be the Internet or any dedicated line. 
     Power source monitoring data processing device  3  is a device that processes the monitoring data of the plurality of power source systems  10  collected by central monitoring system  2 . For example, power source monitoring data processing device  3  may include an information processing device, such as a server, a personal computer (PC), a tablet, or a smartphone. Power source monitoring data processing device  3  acquires the monitoring data of the plurality of power source systems  10  from central monitoring system  2  over the network. Alternatively, power source monitoring data processing device  3  acquires the monitoring data of the plurality of power source systems  10  via a recording medium.  FIG. 1  illustrates the configuration in which power source monitoring data processing device  3  is separated from central monitoring system  2 ; however, a configuration in which power source monitoring data processing device  3  is incorporated in central monitoring system  2  may be possible.  FIG. 1  illustrates the (star type) configuration in which the plurality of power source systems  10  are individually connected to central monitoring system  2 ; however, a different connection configuration, such as a (tree type) hierarchic structure according to a geographic situation or a (loop type) multiplexing intended for stable communication, or a combination of some of these configurations may be possible. 
       FIG. 2  illustrates an example of a configuration of power source system  10  in communication facility  1 . Power source system  10  in  FIG. 2  includes three power sources: system power source  5 , diesel power generation device  11 , and power storage device  12 . Diesel power generation device  11  is a device that generates electric power with a compression ignition scheme by using gas oil as a main fuel and outputs alternating current (AC) power. Instead of diesel power generation device  11 , a gas turbine generator may be used. In this case, the main fuel is natural gas. In some cases, power source system  10  is connected to another power source facility such as a solar photovoltaic system, which is not illustrated in this exemplary embodiment. 
     Switching section  13  selectively outputs AC power supplied from system power source  5  and AC power supplied from diesel power generation device  11 . AC/DC converter  14  converts the AC power supplied via switching section  13  into direct current (DC) power having a predetermined voltage (referred to below as a reference voltage) and outputs the DC power to DC bus  15 . DC bus  15  is connected to DC load  1 L in communication facility  1 . For example, DC bus  15  may be a busbar. 
     DC bus  15  is connected to power storage device  12 , which charges DC bus  15  with the DC power or discharges the DC power from DC bus  15 . This charging or discharging operation is usually controlled based on a state (for example, a voltage or current value) on DC bus  15 . 
     Power storage device  12  includes: a plurality of power storage modules m 1  to mn interconnected in parallel; battery manager  121 ; and switch  122 . Each of power storage modules m 1  to mn includes a plurality of cells connected in series. Each cell may be a lithium ion battery cell, a nickel hydride battery cell, a lead battery, an electric double layer capacitor cell, or a lithium ion capacitor cell, for example. The following description gives an example in which a lithium ion battery cell (nominal voltage: 3.6 V to 3.7 V) is used. Power storage modules m 1  to mn interconnected in parallel are connected to DC bus  15  via switch  122 . For example, switch  122  may be a relay. 
     Battery manager  121  monitors states of the plurality of power storage modules m 1  to mn. More specifically, battery manager  121  monitors voltages, currents, and temperatures of the cells included in the plurality of power storage modules m 1  to mn. Battery manager  121  controls state-of-charge (SOC), state-of-health (SOH), and equalization, and protects the batteries. 
     The SOC can be estimated by a current integration method or an open circuit voltage (OCV) method. The SOH is specified by a ratio of present full charge capacity to initial full charge capacity. This value decreases (approaches zero) as degradation increases. The SOH can be estimated based on a correlation with an internal resistance. The internal resistance can be estimated by dividing a voltage drop occurring when a predetermined current flows through a cell for a given time by the current. The internal resistance has the following relationship: the internal resistance decreases as the temperature rises and increases as the battery degrades. 
     The equalization control refers to control under which a voltage across or a capacity of a plurality of cells interconnected in series is equalized. The battery protection refers to control under which, when an overvoltage, excessively low voltage, overcurrent, or temperature abnormality is detected, switch  122  is turned off to electrically disconnect the plurality of power storage modules m 1  to mn from DC bus  15 . 
     Controller  16  monitors and controls overall power source system  10 . Controller  16  detects first data and second data as basic monitoring data of power source system  10 . The first data refers to a voltage value and/or current value at first point (N 1 ); the second data refers to a voltage value and/or current value at second point (N 2 ). First data is a three-phase or single-phase AC voltage or current value output from switching section  13 . Second data is a DC voltage or current value output from AC/DC converter  14  and/or power storage device  12 . When each of these current values is measured, it is necessary to measure a current value at a point on DC bus  15  between branch node (Nb) of power storage device  12  and DC load  1 L or between branch node (Nb) and power storage device  12 . 
     Controller  16  transmits first and second data measured in the above manner to central monitoring system  2  over the network, as the monitoring data of power source systems  10 , at regular intervals (for example, once in ten minutes). 
     When a power failure occurs in system power source  5 , switching section  13  switches its connection target from system power source  5  to diesel power generation device  11 . This switching operation may be performed in a hardware manner or under software control of controller  16 . After the power failure occurs, diesel power generation device  11  waits for an activation instruction from controller  16 . Battery manager  121  turns on switch  122 . By receiving a power failure sensing signal from a power failure sensor or controller  16 , battery manager  121  recognizes the occurrence of the power failure. 
     A discharge start voltage across power storage modules m 1  to mn is set to be lower than the reference voltage on DC bus  15  by a preset value. After switch  122  is turned on, when the voltage on DC bus  15  becomes lower than the voltage across power storage modules m 1  to mn, power storage device  12  starts discharging electric power to DC bus  15 . After the discharging operation starts, when a remaining capacity of power storage modules m 1  to mn reaches their lower limit, battery manager  121  transmits a discharge termination notification to controller  16 . The lower limit of the remaining capacity refers to a value set to protect a battery by suppressing overdischarge and may be specified by a voltage or the SOC. A lifetime of a storage battery tends to be shortened as a depth of discharge (DOD) is used deeply. 
     In response to reception of the discharge termination notification from battery manager  121 , controller  16  transmits an operation instruction to diesel power generation device  11 . Alternatively, battery manager  121  may be configured to directly transmit the operation instruction to diesel power generation device  11 . Diesel power generation device  11  may have an operation determination function and be configured to perform control in relation to an operational state. When diesel power generation device  11  starts generating electric power in response to reception of the operation instruction, the voltage on DC bus  15  starts increasing. When the voltage on DC bus  15  exceeds the voltage across power storage modules m 1  to mn, charging of the electric power from DC bus  15  to power storage device  12  starts. After the charging operation starts, when the remaining capacity of power storage modules m 1  to mn reaches an upper limit, battery manager  121  transmits a charge termination notification to controller  16 . The upper limit of the remaining capacity refers to a value set to protect a battery by suppressing overcharge and may be specified by a voltage or the SOC. 
     In response to reception of the charge termination notification from battery manager  121 , controller  16  transmits a stop instruction to diesel power generation device  11 . Alternatively, battery manager  121  may be configured to directly transmit the stop instruction to diesel power generation device  11 . Diesel power generation device  11  may have the operation determination function and be configured to perform control in relation to an operational state. When diesel power generation device  11  stops generating the electric power in response to the reception of the stop instruction, the voltage on DC bus  15  starts decreasing. When the voltage on DC bus  15  decreases to below the voltage across power storage modules m 1  to mn, power storage device  12  resumes discharging the electric power. The above control operation is repeated until system power source  5  recovers. 
     As described above, when a power failure occurs in system power source  5 , power source system  10  operates both power storage device  12  and diesel power generation device  11  to supply a backup power source to DC load  1 L until system power source  5  recovers. A basic backup operation is performed such that power storage device  12  is charged in advance and sensing of a power failure triggers power storage device  12  to supply the electric power. When the electric power supplied from power storage device  12  decreases, diesel power generation device  11  is activated. 
       FIG. 3  illustrates an example of a time transition of a state of a power source in certain power source system  10 . When a power failure occurs in system power source  5 , a power source that supplies electric power to DC load  1 L is changed from system power source  5  (denoted by EB in  FIG. 3 ) to power storage device  12  (denoted by Lib in  FIG. 3 ). When this power failure lasts for a long period (see power failure period A), the power source that supplies the electric power to DC load  1 L is alternately switched between power storage device  12  and diesel power generation device  11  (denoted by DG in  FIG. 3 ). When the power failure lasts for only a short period (see power failure period B), power storage device  12  operates alone to serve as the power source that supplies the electric power to DC load  1 L. 
     If the power source in power source system  10  is not controlled in accordance with stability of system power source  5 , diesel power generation device  11  may operate over an unexpectedly long period, thereby causing a problem that diesel power generation device  11  consumes excessive amounts of fuel. Running out of the fuel in diesel power generation device  11  results in shutdown of overall communication facility  1 . In addition, if diesel power generation device  11  operates over a long time, fuel and labor costs may increase. A reason why the labor cost increases is that an engineer needs to manually supply and carry the fuel. 
     Behaviors of all devices in power source system  10  provided in a site where communication facility  1  is installed are not necessarily measured. For example, if diesel power generation device  11  is configured to automatically start up and stop in accordance with a power supply state at the site, no data on start and stop times of diesel power generation device  11  is left. For example, if only data regarding an AC system and an electrical system of DC bus  15  is measured, it is difficult to identify from which system power source  5  or diesel power generation device  11  the data on the AC system has been output. 
     If an enormous number of sites are present, it is difficult to unify specifications of power source systems  10  at all the sites and also difficult to unify machines used as diesel power generation devices  11  and power storage devices  12 . When constructing power source systems  10 , workers sometimes fail to perfectly install and set apparatuses in consideration of differences among the apparatuses and installation environments. 
     Many power source systems  10  in developing countries disable present settings and environment to be checked from the outside. Therefore, it is difficult to verify a fuel consumption. Furthermore, power failures may occur frequently, and power source infrastructure may be complicated. Electric power systems may fail to sufficiently and reliably collaborate with one another. Different patterns of power failures may occur in different sites. Power failures may occur at different times per month, and no exact data may be left. Materials and fuels may be at a higher risk of being stolen in developing countries than in developed countries. 
     Under the above situation, attempts to reduce fuel costs have been made. However, it is difficult to verify results of these attempts, which may reduce motivations for continuing such activities. Hereinafter, a description will be given of a mechanism for using power source monitoring data processing device  3  to efficiently and continuously attempt to reduce fuel costs. 
       FIG. 4  illustrates an example of a configuration of power source monitoring data processing device  3  according to the exemplary embodiment of the present invention. Power source monitoring data processing device  3  includes calculator  31 , communication section  32 , storage section  33 , and user interface (UI) section  34 . Calculator  31  includes data acquisition section  311 , data processor  312 , and report creation section  313 . 
     A configuration of calculator  31  is implemented by cooperation of hardware and software resources. The hardware resource may be a central processing unit (CPU), read only memory (ROM), random access memory (RAM), or any other large scale integrated circuit (LSI). The software resource may be a program, such as an operating system (OS) or an application. Communication section  32  performs a communication process in conformity with a predetermined communication protocol. A configuration of communication section  32  may be implemented by either the cooperation of the hardware and software resources or the hardware resource alone. Storage section  33  is provided with a non-volatile memory, such as a hard disk device (HDD) or a silicon disk drive (SDD). UI section  34  is provided with input devices such as a keyboard, a mouse, a microphone, and a touch panel, and output devices such as a display, speakers, and a printer. 
       FIG. 5  is a flowchart of an example of an operation of power source monitoring data processing device  3  according to the exemplary embodiment of the present invention. A precondition in this operation example is that it is impossible to acquire direct data indicating operational states of system power source  5  and diesel power generation device  11 . In other words, the precondition is that it is impossible to acquire exact data on periods in which system power source  5  is normal, in which a power failure lasts in system power source  5 , in which diesel power generation device  11  generates the electric power, and in which diesel power generation device  11  stops its operation. 
     At step S 10 , data acquisition section  311  acquires the first and second data, as monitoring data (performance data) of power source system  10  being targeted. The monitoring data is preferably collected continuously over a preset period. At step S 11 , data processor  312  applies the first and second data to a predetermined evaluation model, thereby estimating the operational states of system power source  5  and diesel power generation device  11 . The evaluation model may be created based on behaviors of the first and second data for many power source systems  10 . In general, AC waveforms of system power source  5  and diesel power generation device  11  tend to fluctuate with different stabilities. In short, data processor  312  can estimate the operational state of diesel power generation device  11 , based on differences, for example, in stability and time transition of stability between varying AC waveforms of the first and second data. 
     Data processor  312  can also estimate the operational state of power storage device  12 , based on the first and second data. When the first data is substantially zero and the second data falls within a normal range of a current/voltage output to DC load  1 L, data processor  312  estimates that power storage device  12  is in a discharging state. When the first data falls within the normal range of the current/voltage output to DC load  1 L, data processor  312  estimates that power storage device  12  is in a stop/charging state. 
     At step S 12 , data processor  312  generates a modification plan for power storage device  12 , based on the stability of system power source  5  and the operational states of diesel power generation device  11  and power storage device  12  in power source system  10  being targeted. The modification plan for power storage device  12  refers to a modification plan intended to shorten an operational time of diesel power generation device  11 , and is generated by entry of the above parameters in a predetermined modification plan generation model. The modification plan generation model may be created based on engineers&#39; knowledge and/or learning data on a history of modifications of many power source systems  10 . 
     The modification plan generation model exemplified below includes: changing a system configuration of power storage device  12 ; and/or changing settings for power storage device  12 . Used as specific modification items are the number of power storage modules and a discharge lower limit of the power storage modules. In order to shorten an operational time of diesel power generation device  11 , it is necessary to prolong a discharging time of power storage device  12 . A method to achieve this purpose includes: increasing the power storage capacity; and deepen the discharge depth. 
     The power storage capacity may be increased by an increase in the number of power storage modules interconnected in parallel. The discharge depth may be deepened by lowering the discharge lower limit. The discharge lower limit is usually set to a recommended value described in a specification sheet provided by a battery manufacturer, when power storage device  12  is installed. Therefore, power storage device  12  can be used in a deeper region without danger, depending on a usage environment (for example, an ambient temperature) of power storage device  12 . Regardless of whether the modification plan is present, battery manager  121  preferably changes the discharge lower limit in consideration of degradation of a battery. 
     At step S 13 , data processor  312  calculates a predicted value of an operation reduction amount of diesel power generation device  11  if the above modification plan is carried out, based on past operational state data of system power source  5  in power source system  10  being targeted. The operation reduction amount may be calculated from at least one of a shortened time, a fuel reduction amount, and a fuel reduction cost. When the calculation is made from the fuel reduction cost, a net reduction cost is preferably used. More specifically, a value obtained by subtracting an additional cost (for example, a cost of installing additional power storage modules) involved in carrying out the modification plan for power storage device  12  from a fuel reduction cost of diesel power generation device  11  may be used. 
     At step S 14 , data processor  312  compares the calculated predicted value of the operation reduction amount and a predetermined threshold. Predetermined thresholds may be specified for respective additional power storage modules. When the predicted value of the operation reduction amount is less than the predetermined threshold (N at step S 14 ), at step S 21 , suggestion or carrying out of the above modification plan is suspended. When the predicted value of the operation reduction amount is equal to or more than the predetermined threshold (Y at step S 14 ), the above modification plan is suggested or reported to an administrator of power source system  10 . The suggestion or report of the modification plan may be transmitted from communication section  32  to an administrator&#39;s terminal device over the network. Alternatively, the suggestion or report is directly submitted by a service person to the administrator. 
     The case where the predicted value of the operation reduction amount is less than the predetermined threshold refers to a case where carrying out the modification plan is estimated not to greatly improve fuel reduction. The degree of the improvement mainly depends on a pattern of a power failure in system power source  5  within power source system  10  and environment conditions of a place where power source system  10  is installed. Even if additional power storage modules are further installed, some patterns of a power failure in system power source  5  may hinder an improvement in the operation reduction amount of diesel power generation device  11 . However, the pattern of the power failure in system power source  5  and/or the environment conditions may change with time. Therefore, even when the fuel reduction is estimated not to be greatly improved, modification of the system configuration and/or settings of power storage device  12  might contribute to a great improvement in the fuel reduction. 
     When the above modification plan is carried out (Y at step S 15 ), at step S 16 , data acquisition section  311  acquires first and second data, as monitoring data of power source system  10  after the modification plan is carried out. By monitoring a detection value of a sensor (not illustrated) disposed in power storage device  12 , it is possible to sense whether the system configuration and/or settings of power storage device  12  are actually modified in accordance with the modification plan. Alternatively, the modification of the system configuration and/or settings may be sensed in response to reception of a modification completion notification that an operator has entered in a terminal device, over the network. 
     At step S 17 , data processor  312  applies the first and second data acquired after the modification plan is carried out to the above evaluation model, thereby estimating the operational states (performance data) of system power source  5  and diesel power generation device  11 . At step S 18 , based on the estimated operational state (performance data) of system power source  5 , data processor  312  estimates an operational state (estimated data) of diesel power generation device  11  when the modification plan is not carried out. 
     At step S 19 , data processor  312  compares the operational state (performance data) of diesel power generation device  11  acquired after the modification plan is carried out and the operational state (estimated data) of diesel power generation device  11  when the modification plan is not carried out. In this way, data processor  312  estimates an operation reduction amount of diesel power generation device  11  which is attributed to the carrying out of the modification plan. For example, data processor  312  may estimate the operation reduction amount by calculating a difference between operational times of diesel power generation device  11 . At step S 20 , report creation section  313  creates a fuel reduction performance evaluation report that contains the estimated operation reduction amount of diesel power generation device  11 . Then, communication section  32  transmits the created fuel reduction performance evaluation report to the terminal device of the administrator for power source system  10  via the network. Alternatively, the fuel reduction performance evaluation report may be printed out by a printer, which then mailed or handed to the administrator. 
     The processes at steps S 10  to S 20  may be individually performed in power source systems  10  at regular intervals (for example, once a month) or as appropriate. For example, if system power source  5  is being reconstructed for improvement, the above processes may be performed immediately after the reconstruction is completed. After the modification plan is carried out, power source system  10  is regarded as a modified site. Power source monitoring data processing device  3  retains the modified system configuration and/or settings and continues to collect data. 
     After the modification plan is suggested or reported to the administrator at step S 15 , if the modification plan is not carried out (N at step S 15 ), power source system  10  is regarded as a pending site at step S 21 . When a predetermined period (for example three months) passes since power source system  10  is regarded as the pending site (step S 21 ) (Y at step S 22 ), power source monitoring data processing device  3  returns this processing to step S 10 . Then, power source monitoring data processing device  3  regenerates a modification plan for power storage device  12  at steps S 10  to S 13 . An interval period until a modification plan for the pending site is regenerated is set to be longer than an interval period until a modification plan for the modified site is regenerated. The pending site is a site that has limited possibility for improvement or whose administrator does not has a high motivation for improvement. By decreasing a frequency at which a modification plan for the pending site is generated, it is possible to lighten a process load involved in generating the modification plan. 
     According to the foregoing exemplary embodiment, each power source system  10 , which has both diesel power generation device  11  and power storage device  12 , enables efficient and continuous power source backup setting such that the amount of fuel consumed in diesel power generation device  11  is reduced. More specifically, power source monitoring data processing device  3  collects data on each power source system  10  which is generated before and after a modification plan is carried out and then estimates operational states of diesel power generation device  11 , power storage device  12 , and system power source  5 . After that, power source monitoring data processing device  3  generates the modification plan based on the estimated value and creates a fuel reduction performance evaluation report on the carrying out of the modification plan. 
     Power source monitoring data processing device  3  can not only set initial system configuration and design items but also achieve an efficient and continuous operation of facilities in power source systems  10 . In addition, power source monitoring data processing device  3  enables modifications of the system configurations and/or settings of power storage devices  12  in consideration of varying stabilities of system power sources  5  over a long period. Furthermore, power source monitoring data processing device  3  concurrently enables verification of an effect of the modified system configurations and/or settings. Consequently, it is possible to appropriately evaluate an effect of the modification. 
     The above site control enables an efficient and continuous operation of power source system  10 . In addition, by using operational data and performance evaluations in combination, it is possible to quantitatively verify an effect of an improvement suggestion service for fuel reduction. However, this improvement suggestion service is not highly required for a power source system that includes a solar photovoltaic system and a power storage device. A reason is that a cost of generating electric power (a cost of fossil fuel) is constant regardless of whether a system configuration and/or settings of the power storage device are modified. 
     The present invention has been described based on the exemplary embodiment. It is to be understood to a person with ordinary skill in the art that the exemplary embodiment is an example, and various modifications of each of component elements and combinations of each treatment process may be made and the modifications are included within the scope of the present invention. 
     In the foregoing exemplary embodiment, exact operational data of system power source  5  and diesel power generation device  11  is supposed to be unobtainable. At a site where exact operational data of system power source  5  and/or diesel power generation device  11  is obtainable, it is unnecessary to estimate an operational state(s) of system power source  5  and/or diesel power generation device  11 . In this case, the operational data obtained from a measurement may be used directly. At a site where operational or state data of power storage device  12  is obtainable, it is possible to generate a modification plan for a system configuration and/or settings with higher accuracy in consideration of degradation and environment conditions of power storage device  12 . 
     When generating the modification plan at step S 12  in the flowchart of  FIG. 5 , data processor  312  may calculate a comprehensive cost reduction effect in consideration of a long lifetime of a storage battery. In this case, data processor  312  may consider a forecast about a lifetime of a power storage capacity, based on operational data of the storage battery. Furthermore, power source monitoring data processing device  3  may be configured to receive external data, as auxiliary determination information to be used when a modification plan is generated. Power source monitoring data processing device  3  may output, to the outside, as auxiliary information, a summed or estimated value of data that can be used as an evidence for generating a modification plan. Providing an input/output interface in this manner can reflect a decision of a human, such as an engineer in charge, thereby successfully generating a modification plan with higher accuracy. Moreover, it is possible to make an amendment based on a skilled engineer&#39;s experimental rule. 
     Data processor  312  generates statistical data by continuously collecting and summarizing performance data of power source system  10 . This statistical data can be used to sense a sign of any abnormality that may occur in overall equipment and/or each individual facility in power source system  10 . In addition, data processor  312  may amend a system configuration and/or settings of power storage device  12 , based on the sensing result, so that the system configuration and/or settings conform to an aged state and other factors. 
     Instead of or in addition to switch  122 , a DC/DC converter is connected between DC bus  15  and power storage modules m 1  to mn. This configuration enables battery manager  121  to actively control a charging current/voltage and a discharging current/voltage. In short, battery manager  121  can adjust a charging/discharging pattern. In this case, a modified charging/discharging pattern may be added to modified setting items for power storage devices  12 . 
     In the foregoing exemplary embodiment, report creation section  313  is configured to create the fuel reduction performance evaluation report that contains an estimated operation reduction amount of diesel power generation device  11 . Hereinafter, a specific example of the fuel reduction performance evaluation report will be described. 
       FIG. 6  illustrates an example of a format of the fuel reduction performance evaluation report. In performance evaluation report  35  illustrated in  FIG. 6 , reduction amount (time)  36  of an operational time of diesel power generation device  11  is described as a value of a fuel reduction performance over a predetermined period. As the value of the fuel reduction performance over the period, a reduction amount (money amount) of fuel calculated from an operational efficiency and operational time of diesel power generation device  11  and a unit price of fuel used over this period may be described. Alternatively, only a reduction amount (money amount) of fuel may be described. 
     In performance evaluation report  35  illustrated in  FIG. 6 , a time transition performance of an operational state of diesel power generation device  11  over the period is described. In the example of  FIG. 6 , the time transition performance of the operational state is indicated by a time transition graph. If the time transition graph cannot contain the entire period, the time transition graph may indicate only a portion of this period. 
     The above time transition graph corresponds to a graph that visualizes a timing of supply from DG in  FIG. 3 , based on the performance data. Since exact detection information on EB/Lib/DG is supposed to be unobtainable, this time transition graph visualizes an estimated amount based on the performance data. This estimated amount does not represent “an operational state (estimated data) of diesel power generation device  11  when the modification plan is not carried out”, and is a time transition performance of the operational state estimated from the performance data. 
     In addition to the timing of the power supply from DG, the graph may visualize timing(s) of power supply from EB and/or Lib. In this case, a formation of the graph is identical to the format of the graph indicating the time transitions of the states of the power sources in  FIG. 3 . The graph may also visualize a power failure period estimated from the performance data. In  FIG. 3 , the arrows each indicating the power failure period are added to the time transition graph indicating the states of the power sources in  FIG. 3 . 
     A time transition graph that visualizes an operational state (estimated data) where diesel power generation device  11  operates when the modification plan is not carried out may be used. A format of this time transition graph of  FIG. 3  corresponds to a format in which the time transition graphs indicating the states of power sources before and after the modification plan is carried out are described vertically. The time transition graph in this format helps understanding of the degree to which the operation of DG improves. In the time transition graph corresponding to the case where the modification plan is not carried out, not only the timing of the power supply from DG but also the timing(s) of the power supply from EB and/or Lib may be described. In addition, arrows indicating a power failure period may also be described. 
     Optionally, present setting information and/or setting information (past setting information) that indicates a case where the modification plan is not carried out may be described as reference information. Not all site administrators always memorize present and/or past setting state(s). Therefore, the present and/or past setting state(s) is (are) preferably described. 
       FIGS. 7( a ) and 7( b )  each illustrate a modification of graph area  37  of  FIG. 6  in which an operation result and an estimated operation before improvement are shown. Graph area  37   a  in  FIG. 7( a )  is equivalent to graph area  37  in  FIG. 6  to which arrows  38  each indicating a power failure period are added. Graph area  37   b  in  FIG. 7( b )  is equivalent to a format example in which arrows  38  each indicating a power failure period are added and the timings of power supply from EB and/or Lib are described. 
     The exemplary embodiment may be specified by the items described below. 
     [Item 1] 
     Power source monitoring data processing device ( 3 ) including: data acquisition section ( 311 ) that acquires first data and second data as monitoring data of power source system ( 10 ), power source system ( 10 ) including switching section ( 13 ) that selectively outputs alternating current (AC) power supplied from system power source ( 5 ) or internal combustion power generation device ( 11 ), alternating current/direct current (AC/DC) converter ( 14 ) that converts the AC power output from switching section ( 13 ) into direct current (DC) power and outputs the DC power to DC load ( 1 L), and power storage device ( 12 ) connected to DC bus ( 15 ) between AC/DC converter ( 14 ) and DC load ( 1 L), the first data containing an output voltage and/or an output current of switching section ( 13 ), the second data containing an output voltage and/or an output current of power source system ( 10 ); and data processor ( 312 ) that estimates an operational state of internal combustion power generation device ( 11 ), based on the first data and the second data acquired by data acquisition section ( 311 ) and that generates a modification plan for a system configuration and/or a discharge lower limit of power storage device ( 12 ) to shorten an operational time of internal combustion power generation device ( 11 ). 
     Power source monitoring data processing device ( 3 ) configured above achieves a continuous and efficient operation of power source system ( 10 ) in which power storage device ( 12 ) and internal combustion power generation device ( 11 ) collaborate with each other. 
     [Item 2] 
     Power source monitoring data processing device ( 3 ) according to Item 1, in which data processor ( 312 ) estimates the operational state of internal combustion power generation device ( 11 ), based on variations in the first data and the second data. 
     The word “variation” refers to a variation based on at least one of physical quantity variables, such as “stability” and “time transition of stability”. 
     Power source monitoring data processing device ( 3 ) configured above can generate the modification plan for power storage device ( 12 ) even if unable to directly acquire operational data of internal combustion power generation device ( 11 ). 
     [Item 3] 
     Power source monitoring data processing device ( 3 ) according to Item 1 or 2, in which data acquisition section ( 311 ) acquires the first data and the second data of power source system ( 10 ) after the modification plan for power storage device ( 12 ) is carried out, and data processor ( 312 ) estimates the operational state of internal combustion power generation device ( 11 ) and an operational state of system power source ( 5 ) after the modification, based on the first data and the second data of power source system ( 10 ) after the modification, and estimates the operational state of internal combustion power generation device ( 11 ) when the modification plan is not carried out, based on the operational state of system power source ( 5 ), and compares the operational states of internal combustion power generation device ( 11 ) when the modification plan is not carried out and after the modification plan is carried out, to estimate an operation reduction amount of internal combustion power generation device ( 11 ) caused by carrying out of the modification plan. 
     Power source monitoring data processing device ( 3 ) configured above can quantitatively evaluate a fuel reduction effect produced by carrying out of the modification plan. 
     [Item 4] 
     Power source monitoring data processing device ( 3 ) according to Item 3, in which data processor ( 312 ) determines whether to suspend regeneration of the modification plan, based on the operation reduction amount of internal combustion power generation device ( 11 ). 
     Power source monitoring data processing device ( 3 ) configured above can decrease a number of modification plans to be generated, thereby lightening a process load. 
     [Item 5] 
     Power source monitoring data processing device ( 3 ) according to Item 4, in which when the operation reduction amount is smaller than a predetermined threshold or when the modification plan is not carried out over a preset period, data processor ( 312 ) suspends the regeneration of the modification plan. 
     Power source monitoring data processing device ( 3 ) configured above can efficiently utilize a resource of power source monitoring data processing device ( 3 ) by suspending the regeneration of the modification plan for power source system ( 10 ) that is estimated not to produce a great improvement effect. 
     [Item 6] 
     Power source monitoring data processing device ( 3 ) according to any one of Items 1 to 5, in which a modification of the system configuration of power storage device ( 12 ) includes increasing or decreasing a number of power storage modules (m 1  to mn) that constitute power storage device ( 12 ), and data processor ( 312 ) generates the modification plan, based on an increased cost involved in carrying out the modification plan for power storage device ( 12 ) and a decreased cost of a fossil fuel involved in shortening the operational time of internal combustion power generation device ( 11 ). 
     Power source monitoring data processing device ( 3 ) configured above calculates net cost performance when carrying out the modification plan. 
     [Item 7] 
     Power source monitoring data processing device ( 3 ) according to any one of Items 1 to 6, in which data processor ( 312 ) detects an abnormality of power source system ( 10 ), based on the first data and the second data of power source system ( 10 ) acquired after the modification plan for power storage device ( 12 ) is carried out. 
     Power source monitoring data processing device ( 3 ) configured above can efficiently utilize collected data for not only fuel reduction but also other purposes. 
     [Item 8] 
     A power source monitoring data processing method including: acquiring first data and second data as monitoring data of power source system ( 10 ), power source system ( 10 ) including switching section ( 13 ) that selectively outputs alternating current (AC) power supplied from system power source ( 5 ) or internal combustion power generation device ( 11 ), alternating current/direct current (AC/DC) converter ( 14 ) that converts the AC power output from switching section ( 13 ) into direct current (DC) power and outputs the DC power to DC load ( 1 L), and power storage device ( 12 ) connected to DC bus ( 15 ) between AC/DC converter ( 14 ) and DC load ( 1 L), the first data containing an output voltage and/or an output current of switching section ( 13 ), the second data containing an output voltage and/or an output current of power source system ( 10 ); and estimating an operational state of internal combustion power generation device ( 11 ), based on the first data and the second data, and generating a modification plan for a system configuration and/or a discharge lower limit of power storage device ( 12 ) to shorten an operational time of internal combustion power generation device ( 11 ). 
     Power source monitoring data processing device ( 3 ) configured above achieves a continuous and efficient operation of power source system ( 10 ) in which power storage device ( 12 ) and internal combustion power generation device ( 11 ) collaborate with each other. 
     [Item 9] 
     A power source monitoring data processing program that causes a computer to perform functions including; acquiring first data and second data as monitoring data of power source system ( 10 ), power source system ( 10 ) including switching section ( 13 ) that selectively outputs alternating current (AC) power supplied from system power source ( 5 ) or internal combustion power generation device ( 11 ), alternating current/direct current (AC/DC) converter ( 14 ) that converts the AC power output from switching section ( 13 ) into direct current (DC) power and outputs the DC power to DC load ( 1 L), and power storage device ( 12 ) connected to DC bus ( 15 ) between AC/DC converter ( 14 ) and DC load ( 1 L), the first data containing an output voltage and/or an output current of switching section ( 13 ), the second data containing an output voltage and/or an output current of power source system ( 10 ); and estimating an operational state of internal combustion power generation device ( 11 ), based on the first data and the second data, and generating a modification plan for a system configuration and/or a discharge lower limit of power storage device ( 12 ) to shorten an operational time of internal combustion power generation device ( 11 ). 
     Power source monitoring data processing device ( 3 ) configured above achieves a continuous and efficient operation of power source system ( 10 ) in which power storage device ( 12 ) and internal combustion power generation device ( 11 ) collaborate with each other. The computer program may be stored in a non-transitory computer readable medium. 
     REFERENCE MARKS IN THE DRAWINGS 
     
         
         
           
               1 : communication facility 
               1 L: DC load 
               2 : central monitoring system 
               3 : power source monitoring data processing device 
               31 : calculator 
               311 : data acquisition section 
               312 : data processor 
               313 : report creation section 
               32 : communication section 
               33 : storage section 
               34 : UI section 
               5 : system power source 
               10 : power source system 
               11 : diesel power generation device 
               12 : power storage device 
             m 1 , m 2 , mn: power storage module 
               121 : battery manager 
               122 : switch 
               13 : switching section 
               14 : AC/DC converter 
               15 : DC bus 
               16 : controller