JP7673512B2 - Inspection device, inspection system, and inspection method - Google Patents

Description

The present invention relates to an inspection device, an inspection system, and an inspection method, for example, an inspection device, an inspection system, and an inspection method for inspecting deterioration of a power supply control device that controls the output of power generated in a distributed power supply device.

In recent years, the number of homes and buildings equipped with distributed power supply devices that have photovoltaic power generation devices and the like is increasing. Many of these distributed power supply devices are connected to a power distribution system, and the output of electricity generated by the photovoltaic power generation devices and the like to the power distribution system is controlled by a power supply control device (Power Conditioning Subsystem, hereafter also referred to as "PCS") in the distributed power supply device.

Patent No. 5226873

Distributed power supply devices are known to deteriorate over time. For example, in the case of solar power generation devices, it is known that the aluminum electrolytic capacitors in the PCS and the sealing materials in the solar panels deteriorate over time.

Known degradation diagnosis techniques for solar panels include a method for measuring the I-V curve characteristics of solar panels, and a method for identifying cell cracks, disconnections in interconnectors, or poor connections using an EL (Electroluminescence) light-emitting inspection device. Additionally, known degradation diagnosis techniques for PCS include a method for measuring the capacitance value of aluminum electrolytic capacitors in the PCS.

Conventionally, in large-scale power generation systems such as photovoltaic power plants, periodic inspections have been carried out using the above-mentioned methods to grasp the deterioration of the large-scale power generation system over time.
However, in the case of small-scale power generation systems and home solar power generation devices, detailed inspections of deterioration over time are rarely carried out due to the cost-effectiveness considerations of the number of solar power generation devices installed and the running costs.

For example, when inspecting the degree of deterioration of the aluminum electrolytic capacitor in the PCS described above, it is necessary to disassemble the PCS, remove the aluminum electrolytic capacitor from the circuit board, and connect the aluminum electrolytic capacitor to an inspection device to measure the capacitance value, etc., and the time and cost required for the work of diagnosing the deterioration of the PCS cannot be ignored.

The present invention was made in consideration of the above-mentioned problems, and aims to perform a deterioration diagnosis of the PCS simply and quickly.

The inspection device according to a representative embodiment of the present invention is an inspection device for inspecting the deterioration of an aluminum electrolytic capacitor in a power supply control device having an inverter that converts DC power generated by a distributed generator into AC power and outputs it, and is characterized by having a current measurement unit that measures the output current of the inverter, a current waveform generation unit that generates a current waveform that shows the temporal change in the output current measured by the current measurement unit, and a judgment unit that judges whether or not there is distortion in the current waveform generated by the current waveform generation unit.

The inspection device according to the present invention eliminates the need to disassemble the PCS and remove the aluminum electrolytic capacitors, making it possible to diagnose deterioration of the PCS easily and quickly.

1 is a diagram showing a configuration of an inspection system 1 including an inspection device 2 according to a first embodiment. FIG. 2 is a diagram showing an example of the configuration of a power supply control device 6. FIG. 2 is a diagram showing a test circuit used in an experiment on degradation of an aluminum electrolytic capacitor of a PCS conducted by the present inventors prior to filing this application. 4 is a diagram showing the waveform of the output current of the PCS observed in an experiment using the test circuit of FIG. 3. 4 is a diagram showing the waveform of the output current of the PCS observed in an experiment using the test circuit of FIG. 3. 1 is a diagram showing a configuration of an inspection device 2 according to a first embodiment; FIG. 2 is a diagram showing an example of a current waveform of an output current of an inverter of a PCS. FIG. 2 is a diagram showing an example of a current waveform of an output current of an inverter of a PCS. FIG. 2 is a diagram showing an example of a current waveform of an output current of an inverter of a PCS. 4 is a flowchart showing a flow of inspection of a PCS by the inspection device according to the first embodiment. FIG. 11 is a diagram showing a configuration of an inspection device according to a second embodiment. FIG. 13 is a diagram showing the output current of the inverter of the PCS when the solar power generation device is generating power. FIG. 13 is a diagram showing the output current of the inverter of the PCS when the solar power generation device is generating power. FIG. 13 is a diagram showing the output current of the inverter of the PCS when the solar power generation device is generating power. 10 is a flowchart showing a flow of inspection of a PCS by an inspection device according to a second embodiment.

1. Overview of the embodiment First, an overview of a representative embodiment of the invention disclosed in this application will be described. Note that in the following description, as an example, reference numerals in the drawings corresponding to components of the invention are given in parentheses.

[1] The inspection device (2, 2A) according to a representative embodiment of the present invention is an inspection device for inspecting the deterioration of an aluminum electrolytic capacitor (Cdc) in a power supply control device (6) having an inverter (62) that converts DC power generated by a distributed generator (5) into AC power and outputs it, and is characterized by having a current measurement unit (22) that measures the output current (iac) of the inverter, a current waveform generation unit (24) that generates a current waveform that shows the temporal change in the output current measured by the current measurement unit, and a judgment unit (25) that judges whether or not the current waveform generated by the current waveform generation unit is distorted.

[2] In the inspection device (2, 2A) described in [1] above, the determination unit may compare a sinusoidal reference waveform with the current waveform generated by the current waveform generation unit, and determine the presence or absence of the distortion based on the comparison result.

[3] The inspection device (2A) described in [1] or [2] above may further include a power measurement unit (26) that measures the power generated by the distributed generator, and a judgment execution instruction unit (27) that instructs the judgment unit to execute a process to judge the presence or absence of the distortion when the measured value of the generated power falls by a predetermined percentage with respect to the maximum power generated by the distributed generator in a day.

[4] The inspection device described in any one of [1] to [3] above may further include a communication unit (21) that communicates with the power supply control device via a wide area network, and the current measurement unit may obtain a measurement value of the output current via the communication unit.

[5] The inspection system (1) according to a representative embodiment of the present invention is characterized by comprising a plurality of distributed power supply devices (4_1 to 4_n) each having the distributed generator (5) and the power supply control device (6), and the inspection device (2) described in [4] above that is communicatively connected to the plurality of distributed power supply devices via the wide area network.

[6] A representative embodiment of the present invention provides an inspection method for inspecting deterioration of an aluminum electrolytic capacitor in a power supply control device having an inverter that converts DC power generated by a distributed generator into AC power and outputs the converted power, using an information processing device, and is characterized in that the method includes a first step (S1) in which the information processing device measures the output current of the inverter, a second step (S2) in which the information processing device generates a current waveform that shows the temporal change in the output current measured in the first step, and a third step (S3) in which the information processing device determines whether or not the current waveform generated in the second step is distorted.

2. Specific Examples of the Embodiments Specific examples of the embodiments of the present invention will be described below with reference to the drawings. In the following description, components common to the respective embodiments are designated by the same reference numerals, and repeated description will be omitted.

First Embodiment
FIG. 1 is a diagram showing a configuration of an inspection system 1 including an inspection device 2 according to a first embodiment.

The inspection system 1 shown in Figure 1 includes a power distribution system 3 that supplies electricity generated at a large-scale power generation facility to multiple consumers, distributed power supply devices 4_1 to 4_n (n is an integer of 2 or more) installed at each consumer, an inspection device 2, and a communication network 8 that connects the inspection device 2 and each of the distributed power supply devices 4_1 to 4_n.
Hereinafter, when there is no need to distinguish between the distributed power supply devices 4_1 to 4_n, they will also be simply referred to as "distributed power supply devices 4."

The power distribution system 3 is used to connect devices that transmit power to devices that receive power, and is realized by, for example, power distribution lines and transformers.

Consumers include, for example, not only ordinary households, but also buildings and factories. Equipment at the consumer includes, for example, a consumer load 7 and a distributed power supply unit 4. The consumer load 7 is an appliance that can be operated by power from electrical equipment installed in the consumer's facility. The consumer load 7 is connected to the wiring system via a transformer, and the three-phase power of the distribution system is stepped down to single-phase power for the home and supplied to the consumer load 7.

The distributed power supply device 4 supplies the power it generates to the consumer load 7. The distributed power supply device 4 may store the generated power. In addition, the distributed power supply device 4 is connected to the power distribution system 3, and is capable of supplying the power generated or stored in the distributed power supply device 4 to the power distribution system 3.

The distributed power supply device 4 has a distributed generator 5 and a power supply control device 6 that controls the distributed generator 5 and controls the output of the electricity generated by the distributed generator 5 to the power distribution system 3 and the consumer load 7.

Examples of the distributed generator 5 include a solar power generation system and a household fuel cell. In this embodiment, as an example, the distributed generator 5 is described as a solar power generation system (PV). Note that in addition to the solar power generation system, a wind power generation system, a biomass power generation system, etc. may also be connected to the power distribution system 3.

The power supply control device 6 is a device that controls the output of the power generated by the distributed generators 5 to the power distribution system 3 and the consumer loads 7. The power supply control device 6 is, for example, a PCS. Hereinafter, the power supply control device 6 is also referred to as "PCS6."

The PCS 6 mainly has the function of converting the DC power generated by the distributed generators 5 into AC power and outputting it to the power distribution system 3 and consumer loads 7, the function of measuring the physical quantities such as the power generated by the distributed generators 5 and the AC power, current, voltage, temperature, etc. output to the power distribution system 3, and the function of communicating with external devices via the communication network 8.

Figure 2 shows an example of the configuration of the power supply control device 6.

As shown in FIG. 2, the PCS 6 includes a DC/DC converter 61, an inverter (AC/DC converter) 62, an integrated control unit 63, a measurement unit 64, and a communication unit 65 as means for realizing the above-mentioned functions.

The DC/DC converter 61 is a device that boosts and outputs the DC voltage generated by the solar panel serving as the distributed generator 5. A smoothing capacitance (stabilizing capacitance) Cdc that smoothes the voltage boosted by the DC/DC converter 61 is connected to the output terminal of the DC/DC converter 61. The smoothing capacitance Cdc is an aluminum electrolytic capacitor.

The inverter 62 is a device that converts the DC voltage output from the DC/DC converter 61 into an AC voltage that can be supplied to the power distribution system 3 and outputs it.

The general control unit 63 is a functional unit that controls each device that constitutes the PCS 6 in a general manner, and is, for example, a microcontroller. The measurement unit 64 is a functional unit that measures the power generated by the distributed generator 5, the output voltage vac and current iac of the inverter 62, temperature, etc., and is configured to include various sensors such as a wattmeter, a voltmeter, an ammeter, and a temperature sensor.

The communication unit 65 is a functional unit for communicating with external devices via the communication network 8. The communication network 8 is, for example, a wide area network (WAN) such as the Internet. The communication unit 65 transmits the measurement results of the measurement unit 64 to the inspection device 2 by communicating with the inspection device 2 described below.

Inspection device 2 is a device for inspecting the deterioration of the aluminum electrolytic capacitor (smoothing capacitance Cdc) in PCS 6.

Before explaining the details of the inspection device 2, we will now explain the results of experiments conducted by the inventors regarding the deterioration of aluminum electrolytic capacitors in PCS.

The inventors of the present application found through experiments conducted prior to the present invention that when the capacitance value of the aluminum electrolytic capacitor serving as the smoothing capacitance Cdc in the PCS 6 decreases, distortion occurs in the waveform of the output current iac of the inverter 62. This will be explained in detail below.

Figure 3 shows the test circuit used in an experiment conducted by the inventors of the present application prior to filing this application regarding the deterioration of the aluminum electrolytic capacitors of the PCS.

As shown in FIG. 3, the photovoltaic cell (solar panel) was simulated by a DC power supply 51 that outputs a DC voltage, and the power distribution system 3 was simulated by a low-voltage system simulated power supply (AC power supply) 52 that outputs an AC voltage. In addition, the DC voltage generated by the DC power supply 51 was applied between the input terminals P and N of the PCS 53 to be inspected, and a resistor equivalent to several kW was connected between the output terminals U, O, and W of the PCS 53, so that the power of the DC power supply 51 simulating the solar cell was consumed by the resistor.

In this experiment, the capacitance value of the smoothing capacitance connected to the input terminal of the inverter in PCS53 (output terminal of the DC/DC converter) was changed, and the AC current waveform output from the inverter in PCS53 for each capacitance value was observed using power quality analyzer54.

Figures 4A and 4B show the waveforms of the output current of the PCS observed in an experiment using the test circuit of Figure 3.

In Figures 4A and 4B, the horizontal axis represents time and the vertical axis represents current. Figure 4A shows the waveforms of the output current of the inverter before and after changing the capacitance value of the smoothing capacitance connected to the output terminal of the DC/DC converter in Company A's PCS. Specifically, reference numeral 301 shows the current waveform of the output of Company A's PCS when the capacitance value of the smoothing capacitance is 3400 μF (specification value), and reference numeral 302 shows the current waveform of the output of Company A's PCS when the capacitance value of the smoothing capacitance is 1360 μF (40% of the specification value).

Figure 4B also shows the waveforms of the inverter output current before and after changing the capacitance value of the smoothing capacitance connected to the output terminal of the DC/DC converter in the PCS manufactured by Company B. Specifically, reference numeral 303 shows the current waveform of the output of the PCS manufactured by Company B when the capacitance value of the smoothing capacitance is 2400 μF (specification value), and reference numeral 304 shows the current waveform of the output of the PCS manufactured by Company B when the capacitance value of the smoothing capacitance is 1800 μF (75% of the specification value).

The capacitance value of the smoothing capacitance of each PCS was changed by removing some of the multiple aluminum electrolytic capacitors connected in parallel that make up the smoothing capacitance.

As shown in Figures 4A and 4B, it was found that when the capacitance value of the smoothing capacitance of the PCS decreases, distortion occurs in the sinusoidal current waveform output from the PCS. Specifically, when the aluminum electrolytic capacitor serving as the smoothing capacitance of the PCS deteriorates, the capacitance value of the aluminum electrolytic capacitor decreases, and the voltage that pulsates at twice the commercial frequency at which the PCS is affected by the sine wave of the commercial power supply when connected to the grid becomes a ripple voltage.

The inverter uses the DC voltage with this ripple voltage superimposed as a control command value for converting it into AC power, so the AC voltage output from the inverter also has a ripple voltage pulsating at twice the commercial frequency superimposed on it. This distorts the output current of the inverter, as shown in Figure 4A.

If the aluminum electrolytic capacitor continues to deteriorate and its capacitance value drops further, the control command value reaches the upper or lower limit of the DC voltage control amount, causing large fluctuations in the output power. As a result, as shown in Figure 4B, a section occurs in which the inverter output current drops sharply, and the distortion of the output current becomes more pronounced.

As explained above, it has become clear that when the aluminum electrolytic capacitor connected to the PCS inverter as a smoothing capacitance deteriorates, distortion occurs in the output current of the PCS inverter.

The inspection device 2 according to the first embodiment monitors the current waveform of the inverter output of the PCS 6, and determines whether the aluminum electrolytic capacitor of the PCS has deteriorated based on the presence or absence of distortion in the current waveform.

FIG. 5 is a diagram showing a configuration of an inspection device 2 according to the first embodiment.
The inspection device 2 is an information processing device, for example, a server connected to a wide area communication network 8 such as the Internet.

The inspection device 2 may be realized as one of the functions of a centralized management device (server) that monitors the power supply and demand state of the power supply network 1 and comprehensively controls the entire power supply network 1 to ensure a stable power supply.

As shown in FIG. 5, the inspection device 2 has a communication unit 21, a current measurement unit 22, a memory unit 23, a current waveform generation unit 24, and a judgment unit 25.

The communication unit 21 is a functional unit that communicates with the PCS 6 of the distributed power supply device 4 at each consumer via a wide area network. The current measurement unit 22 is a functional unit that measures the current output from the PCS 6 (inverter 62). Specifically, the current measurement unit 22 acquires time series data of the measurement value of the output current iac of the inverter 62 measured by the measurement unit 64 of the PCS 6 via the communication unit 21, and stores it in the memory unit 23.

The memory unit 23 is a functional unit that stores various data necessary for diagnosing the deterioration of the aluminum electrolytic capacitor of the PCS 6. The memory unit 23 stores, for example, current measurement value information 231 including the measurement value of the output current iac of the inverter 62 acquired from the PCS 6 described above, reference waveform information 232 used in the deterioration determination process described below, and determination result information 233 including the determination result of the deterioration determination process.

The current waveform generating unit 24 is a functional unit that generates a current waveform that indicates the change over time in the output current iac of the inverter 62 measured by the current measuring unit 22. Specifically, the current waveform generating unit 24 generates current waveform data based on the time series data of the output current iac of the PCS 6 being inspected, which is stored in the memory unit 23.

The determination unit 25 is a functional unit that performs a deterioration determination process to determine whether or not the current waveform generated by the current waveform generation unit 24 is distorted. Specifically, the determination unit 25 compares a sinusoidal reference waveform that serves as a reference for the current waveform of the output current iac of the inverter 62 with the current waveform generated by the current waveform generation unit 24, and determines whether or not distortion is present based on the comparison result. As described above, the information on the reference waveform is stored in advance in the memory unit 23 as reference waveform information 232.

Figures 6A to 6C are diagrams showing an example of the current waveform of the output current iac of inverter 62 of PCS6.

In FIG. 6A, reference numeral 600 denotes a sinusoidal reference waveform that is the reference for the output current iac of the inverter 62, and reference numeral 601 denotes a measured current waveform of the AC current iac of the inverter 62 when the aluminum electrolytic capacitor serving as the smoothing capacitance Cdc of the PCS 6 has not deteriorated. In FIG. 6B, reference numeral 602 denotes a measured current waveform of the AC current iac of the inverter 62 when the aluminum electrolytic capacitor serving as the smoothing capacitance Cdc of the PCS 6 has begun to deteriorate. In FIG. 6C, reference numeral 603 denotes a current waveform when the deterioration of the aluminum electrolytic capacitor serving as the smoothing capacitance Cdc of the PCS 6 has progressed further.

As shown in FIG. 6A, when the measured current waveform 601 of the output current iac of the inverter 62 substantially matches the reference waveform 600, the determination unit 25 determines that the aluminum electrolytic capacitor serving as the smoothing capacitance Cdc has not deteriorated.

On the other hand, as shown in Figures 6B and 6C, if the measured current waveforms 602, 603 of the output current iac of the inverter 62 differ significantly from the reference waveform 600, the determination unit 25 determines that the aluminum electrolytic capacitor serving as the smoothing capacitance Cdc has deteriorated.

The determination unit 25 stores the determination results from the deterioration determination process in the memory unit 23 as determination result information 233 for each PCS 6 of the customer being inspected.

The determination unit 25 may determine the degree of deterioration of the aluminum electrolytic capacitor according to the degree of agreement between the measured current waveform of the output current iac of the inverter 62 and the reference waveform 600. For example, in the case of the current waveform 601 shown in FIG. 6A, the degree of deterioration of the aluminum electrolytic capacitor may be determined to be "small (or no deterioration)", in the case of the current waveform 602 shown in FIG. 6B, the degree of deterioration of the aluminum electrolytic capacitor may be determined to be "medium", and in the case of the current waveform 603 shown in FIG. 6C, the degree of deterioration of the aluminum electrolytic capacitor may be determined to be "large".

The determination unit 25 may also display the measured current waveform of the output current iac of the inverter 62 together with the reference waveform 600 on the screen of a display device connected to the inspection device 2 directly or indirectly via a network. This allows the person in charge of the inspection, etc., to visually check the degree of distortion of the output current iac.

Figure 7 is a flowchart showing the flow of PCS inspection using the inspection device 2 according to embodiment 1.

For example, after selecting the distributed power supply device 4 of the consumer to be inspected, the inspection device 2 first measures the output current of the PCS 6 to be inspected (step S1). Specifically, as described above, the current measurement unit 22 of the inspection device 2 communicates with the PCS 6 to be inspected via the communication unit 21 to obtain time series data of the output current of the PCS 6 to be inspected, and stores the data in the memory unit 23.

Next, the current waveform generating unit 24 of the inspection device 2 generates a current waveform of the output current based on the time series data of the output current of the PCS 6 to be inspected stored in the memory unit 23 in step S1 (step S2).

Next, the determination unit 25 of the inspection device 2 determines whether or not the current waveform generated in step S2 is distorted using the method described above (step S3). If the current waveform is not distorted (step S3: NO), the determination unit 25 determines that the aluminum electrolytic capacitor of the PCS 6 of the inspection device 2 is not degraded, and stores the determination result in the memory unit 23 (step S4). On the other hand, if the current waveform is distorted (step S3: YES), the determination unit 25 determines that the aluminum electrolytic capacitor of the PCS 6 of the inspection device 2 is degraded, and stores the determination result in the memory unit 23 (step S5).

As described above, the inspection device 2 according to the first embodiment measures the output current of the inverter 62 of the PCS 6, generates a current waveform showing the change in the output current over time, and determines whether or not the current waveform is distorted, thereby determining whether or not the aluminum electrolytic capacitor serving as the smoothing capacitance Cdc connected to the inverter 62 of the PCS 6 has deteriorated.

As described above, if the aluminum electrolytic capacitor serving as the smoothing capacitance Cdc in the PCS 6 is degraded, the capacitance of the aluminum electrolytic capacitor decreases and the waveform of the inverter output current is distorted. Therefore, by monitoring the waveform of the output current, the presence or absence of degradation of the aluminum electrolytic capacitor can be appropriately determined. This eliminates the need for work such as disassembling the PCS 6 to remove the aluminum electrolytic capacitor, making it possible to reduce the time and cost required for diagnosing the deterioration of the PCS. In other words, the inspection device 2 according to this embodiment makes it possible to perform a deterioration diagnosis of the PCS easily and in a short time.

Furthermore, the inspection device 2 compares the current waveform of the output current iac of the inverter 62 in the PCS 6 under inspection with the sinusoidal reference waveform, and determines whether or not the current waveform is distorted based on the comparison result.
This makes it possible to easily determine whether or not there is distortion in the current waveform of the output current, thereby making it possible to more accurately and easily determine whether or not the PCS has deteriorated.

Furthermore, the inspection device 2 acquires a measurement value of the output current iac of the inverter 62 of the PCS 6 by communicating with the PCS 6 via the communication network 8, which is a wide area network.
This allows the inspection officer to inspect each consumer's PCS 6 from a remote location without having to travel to the location where the PCS being inspected is installed, thereby further reducing the time and cost required for PCS deterioration diagnosis.

Second Embodiment
FIG. 8 is a diagram showing a configuration of an inspection device 2A according to the second embodiment.
The inspection device 2A of embodiment 2 differs from the inspection device 2A of embodiment 1 in that it starts the deterioration determination process of the PCS based on the generated power of the distributed power supply device 4 being inspected, but is similar to the inspection device 2A of embodiment 1 in other respects.

The inventors of the present application, through research conducted prior to the present invention, discovered that when the aluminum electrolytic capacitor connected to the PCS inverter as a smoothing capacitance is deteriorated and the generated power of the photovoltaic power generation device is reduced due to a decrease in the amount of solar radiation, the distortion of the output current of the PCS inverter becomes evident. This will be explained in detail below with reference to the figures.

Figures 9A to 9C show the output current of the PCS inverter 62 when the solar power generation device is generating power.

9A to 9C show waveforms of output current of the PCS for each amount of solar radiation when the smoothing capacitance of the PCS manufactured by Company A is set to 1360 μF (40% of the specification value) and power is generated by a solar power generation device. Specifically, FIG. 9A shows experimental results of current 901 on the positive side and current 902 on the negative side of the inverter of the PCS manufactured by Company A when the amount of solar radiation is 1 kW/ ^m2 . FIG. 9B shows experimental results of current 903 on the positive side and current 904 on the negative side of the inverter of the PCS manufactured by Company A when the amount of solar radiation is 0.9 kW/ ^m2 . FIG. 9C shows experimental results of current 903 on the positive side and current 904 on the negative side of the inverter of the PCS manufactured by Company A when the amount of solar radiation is 0.8 kW/ ^m2 .

As can be seen from Figures 9A to 9C, the more the power generated by the photovoltaic power generation device decreases due to a decrease in the amount of solar radiation, the more pronounced the distortion of the output current of the PCS inverter becomes. Therefore, the inspection device 2A according to the second embodiment monitors the amount of power generated by the distributed power supply device 4, and when the amount of power generated decreases to a certain degree, it executes a PCS degradation determination process.

Specifically, as shown in FIG. 8, the inspection device 2A has a power acquisition unit 26 and an inspection execution instruction unit 27. The power acquisition unit 26 is a functional unit that acquires the measurement value of the power generated by the photovoltaic power generation device serving as the distributed generator 4. The power acquisition unit 26 acquires the measurement value of the power generated by the distributed generator 4 measured by the measurement unit 64 of the PCS 6 from the PCS 6 via the communication unit 21, and stores it in the memory unit 23 as power measurement value information 234.

The inspection execution instruction unit 27 is a functional unit that outputs an instruction to execute a deterioration determination process for the PCS 6 to the determination unit 25. The inspection execution instruction unit 27 instructs the determination unit 25 to execute a deterioration determination process when the power generated by the distributed generator 4 has decreased by a predetermined percentage (e.g., 20%) of the maximum power generated by the distributed generator 4 in a day.

For example, in the case where the generated power when the amount of solar radiation shown in FIG. 9A is 1 kW/ ^m2 is the maximum generated power for that day, when the amount of solar radiation falls to 0.8 kW/ ^m2 , the inspection execution instruction unit 27 instructs the judgment unit 25 to execute a deterioration judgment process.

The determination unit 25, which receives instructions from the test execution instruction unit 27, determines whether or not the current waveform is distorted by comparing the current waveform generated by the current waveform generation unit 24 with a reference waveform.

The current measurement unit 26 and the current waveform generation unit 24 may obtain the measurement value of the current iac and generate the current waveform regardless of the instruction to execute the deterioration determination process from the inspection execution instruction unit 27, or may obtain the measurement value of the current iac and generate the current waveform after receiving an instruction to execute the deterioration determination process from the inspection execution instruction unit 27.

Figure 10 is a flowchart showing the flow of PCS inspection using inspection device 2A according to embodiment 2.

For example, the inspection device 2A selects the distributed power supply device 4 of the consumer to be inspected, and then the power measurement unit 26 of the inspection device 2A acquires the measurement value of the generated power of the distributed generator (photovoltaic power generation device) 5 of that distributed power supply device 4 (step S11).

Next, the inspection execution instruction unit 27 of the inspection device 2A determines whether the power generated by the distributed generator (photovoltaic power generation device) 5 of the distributed power supply device 4 being inspected has decreased based on the measured value of the generated power acquired in step S11 (step S12). Specifically, as described above, the inspection execution instruction unit 27 determines whether the power generated by the distributed generator 5 has decreased by a predetermined percentage (e.g., 20%) of the maximum power generated by the distributed generator 5 in a day.

If the power generated by the distributed generator 5 has not decreased by a predetermined percentage relative to the maximum power generated (step S12: NO), the inspection execution instruction unit 27 does not instruct the determination unit 25 to execute the deterioration determination process. In this case, the inspection device 2A returns to step S11 again and continues to monitor the power generated by the distributed power supply device 4 being inspected.

On the other hand, if the power generated by the distributed generator 5 has decreased by a predetermined percentage relative to the maximum power generated (step S12: YES), the inspection execution instruction unit 27 instructs the determination unit 25 to execute a deterioration determination process. As a result, the processes from steps S1 to S5 are executed, as in the inspection device 2 according to embodiment 1, and the presence or absence of deterioration of the PCS 6 being inspected is inspected.

As described above, the inspection device 2 of embodiment 2 determines whether or not there is distortion in the current waveform when the power generated by the distributed power generation device 4 being inspected drops by a predetermined percentage compared to the maximum daily power generated by the distributed power generation device 4.
According to this, the inspection device 2A automatically inspects the PCS at the appropriate time, thereby reducing the workload of the inspection staff, etc., and making it possible to further reduce the time and cost required for work to diagnose deterioration of the PCS.

<<Extension of the embodiment>>
The invention made by the inventors of the present application has been specifically described above based on an embodiment, but it goes without saying that the present invention is not limited thereto and can be modified in various ways without departing from the spirit of the invention.

For example, the above-mentioned flowchart shows an example for explaining the operation, and is not limited to this. In other words, the steps shown in each figure of the flowchart are specific examples, and are not limited to this flow. For example, the order of some of the processes may be changed, other processes may be inserted between each process, and some processes may be performed in parallel.

1...inspection system, 2, 2A...inspection device, 3...power distribution system, 4, 4_1 to 4_n...distributed power supply devices, 5...distributed generators (photovoltaic power generation devices), 6...power supply control device (PCS), 7...consumer load, 8...communication network, 61...DC/DC converter, 62...inverter, Cdc...smoothing capacitance (aluminum electrolytic capacitor), 63...general control unit, 64...measurement unit, 65...communication unit, ia...output current of inverter 62.

Claims (5)

An inspection device for inspecting deterioration of an aluminum electrolytic capacitor in a power supply control device having an inverter that converts DC power generated by a distributed generator into AC power and outputs the AC power,
a current measuring unit that measures an output current of the inverter;
a current waveform generating unit that generates a current waveform indicating a change over time of the output current measured by the current measuring unit;
a determination unit that determines whether or not there is distortion in the current waveform generated by the current waveform generation unit;
a power measurement unit that measures the power generated by the distributed generator;
and a judgment execution instruction unit that instructs the judgment unit to execute a process to judge whether or not the distortion exists when the measured value of the generated power drops by a predetermined percentage from the maximum daily generated power by the distributed generator . 2. The inspection device according to claim 1,
The determination unit compares a sinusoidal reference waveform with the current waveform generated by the current waveform generation unit, and determines whether or not the distortion is present based on a comparison result. The inspection device according to claim 1 or 2 ,
A communication unit that communicates with the power supply control device via a wide area network,
The current measuring unit obtains the measurement value of the output current via the communication unit. a plurality of distributed power supply devices each having the distributed generator and the power supply control device;
An inspection system comprising: the inspection device according to claim 3 , communicably connected to the plurality of distributed power supply devices via the wide area network. 1. An inspection method for inspecting deterioration of an aluminum electrolytic capacitor in a power supply control device having an inverter that converts DC power generated by a distributed generator into AC power and outputs the AC power, using an information processing device, comprising:
A first step in which the information processing device measures power generated by the distributed generator;
a second step in which the information processing device determines whether or not the measured value of the generated power in the first step has decreased by a predetermined percentage with respect to a maximum power generated in one day by the distributed power generator;
a third step of measuring an output current of the inverter when the information processing device determines in the second step that the measured value of the generated power has decreased by a predetermined percentage with respect to the maximum generated power of the day ;
a fourth step in which the information processing device generates a current waveform indicating a change over time of the output current measured in the third step;
a fifth step of determining whether or not the current waveform generated in the fourth step is distorted by the information processing device.

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