Diagnostic device, diagnostic method, and computer program for power supply equipment.

Abstract

Providing diagnostic devices, diagnostic methods, and computer programs for power supply equipment. [Solution] The system includes: an acquisition unit that acquires measurement data relating to the voltage and current values ​​of a capacitor used in the power conversion circuit portion of a power supply device; a derivation unit that uses the measurement data of the voltage and current values ​​of the capacitor when the capacitor's voltage control value is controlled to be substantially constant, the output voltage value of the power conversion circuit is near the minimum value, and the output current value of the power conversion circuit is near the maximum value to derive the frequency characteristics of the impedance component in the capacitor; a calculation unit that calculates the capacitance and equivalent series resistance value of the capacitor from the derived frequency characteristics of the impedance component; and an estimation unit that estimates the degradation state of the capacitor based on the calculated capacitance and equivalent series resistance value.

Description

Technical Field

[0001] The present invention relates to a diagnostic apparatus, a diagnostic method, and a computer program for a power supply device.

Background Art

[0002] A power supply device includes, for example, a converter that converts alternating current to direct current, and an inverter that converts the direct current converted by the converter to alternating current, as a power conversion circuit. A capacitor for smoothing the power input to the inverter is connected to this power conversion circuit portion.

[0003] The capacitor has the characteristic that its capacitance decreases, and it is a lifetime component that must be periodically replaced to maintain the performance of the device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since there is no effective diagnostic technology for power supply devices that are actually in operation, the life and abnormalities of the capacitor are determined after the power supply device fails, and it is difficult to establish an appropriate maintenance plan.

[0006] An object of the present invention is to provide a diagnostic apparatus, a diagnostic method, and a computer program for a power supply device that can estimate the deterioration state of a capacitor used in the power conversion circuit portion of the power supply device and be useful for a maintenance plan.

Means for Solving the Problems

[0007] A diagnostic device for power supply equipment according to one aspect of the present invention includes: an acquisition unit that acquires measurement data relating to the voltage and current values ​​of a capacitor used in the power conversion circuit portion of the power supply equipment; a derivation unit that derives the frequency characteristics of the impedance component in the capacitor using the measurement data of the voltage and current values ​​of the capacitor when the capacitor's voltage control value is controlled to be substantially constant, the output voltage value of the power conversion circuit is near the minimum value, and the output current value of the power conversion circuit is near the maximum value; a calculation unit that calculates the capacitance and equivalent series resistance value of the capacitor from the derived frequency characteristics of the impedance component; and an estimation unit that estimates the degradation state of the capacitor based on the calculated capacitance and equivalent series resistance value. [Effects of the Invention]

[0008] According to the above embodiment, the degradation state of capacitors used in the power conversion circuit portion of power supply equipment can be estimated and used for maintenance planning. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing an example configuration of the diagnostic system according to Embodiment 1. [Figure 2] This is a block diagram showing the internal configuration of a diagnostic device. [Figure 3A] This graph shows the time variation of ripple current when the input voltage of a power supply device is changed. [Figure 3B] This graph shows the time variation of ripple current when the input voltage of a power supply device is changed. [Figure 4] This is a flowchart illustrating the steps of the process performed by the diagnostic device. [Figure 5] This is a schematic diagram showing an example of the output of the estimation results. [Figure 6] This is a schematic diagram illustrating an example of a learning model configuration. [Figure 7] This graph shows the change in the degree of capacitor degradation over time. [Modes for carrying out the invention]

[0010] (1) The diagnostic device for power supply equipment of the present disclosure includes: an acquisition unit that acquires measurement data relating to the voltage value and current value of a capacitor used in the power conversion circuit portion of the power supply equipment; a derivation unit that derives the frequency characteristics of the impedance component in the capacitor using the measurement data of the voltage value and current value of the capacitor when the capacitor is controlled so that the voltage control value of the capacitor is substantially constant, the output voltage value of the power conversion circuit is near the minimum value, and the output current value of the power conversion circuit is near the maximum value; a calculation unit that calculates the capacitance and equivalent series resistance value of the capacitor from the derived frequency characteristics of the impedance component; and an estimation unit that estimates the deterioration state of the capacitor based on the calculated capacitance and equivalent series resistance value.

[0011] Capacitors used in the power conversion circuit of power supply equipment include smoothing capacitors that smooth the power input to the power conversion circuit. Ripple voltage and ripple current generated in the power conversion circuit flow into such capacitors. As a result, internal heat generation, which is a factor in capacitor degradation, is likely to occur. Capacitors used in the power conversion circuit of power supply equipment have a shorter lifespan and are one of the components with a high failure rate compared to other components.

[0012] However, there are no effective diagnostic techniques for power supply equipment that is actually in operation. Therefore, the lifespan and abnormalities of capacitors are only determined after the power supply equipment has failed. While maintenance and replacement are generally based on reliability engineering bathtub curves (failure rate curves), this does not take into account the actual operating conditions of the power supply equipment, making it difficult to create an appropriate maintenance plan. Replacing capacitors used in power conversion circuits is a very large-scale operation, as it must be done on-site. In some cases, the entire power supply equipment may need to be replaced, resulting in significant economic losses. From a maintenance perspective, it is preferable to replace capacitors proactively through periodic inspections.

[0013] According to the diagnostic device described in (1) above, measurement data of capacitor voltage and current is acquired from power supply equipment in actual operation via a communication network, and the degradation state of the capacitor is estimated based on the acquired measurement data. Therefore, the diagnostic device can continuously monitor the degradation state of the capacitor over the period until the capacitor degrades (for example, a period of 10 years), which can be useful for maintenance planning of power supply equipment. In the diagnostic device described in (1) above, when calculating the impedance component of the capacitor, measurement data measured under conditions in which the current value is large is used, so the accuracy of the impedance component calculation can be improved.

[0014] (2) In the diagnostic device described in (1) above, the acquisition unit may periodically acquire measurement data relating to the voltage and current values ​​of the capacitor, and the estimation unit may estimate the lifespan of the capacitor by deriving the time-series change in the degradation state of the capacitor based on the capacitance and equivalent series resistance value calculated by the calculation unit.

[0015] According to the diagnostic device described in (2) above, the lifespan of a capacitor can be estimated by periodically estimating the degradation state of the capacitor. As a result, the diagnostic device can prompt the user to perform maintenance work on the power supply equipment, including capacitor replacement, before the capacitor reaches the end of its lifespan.

[0016] (3) The diagnostic device described in (1) or (2) above may be equipped with a learning unit that learns the criteria for estimating the deterioration state of the capacitor.

[0017] According to the diagnostic device described in (3) above, the criteria for estimating the degradation state of the capacitor are determined through learning. Since the diagnostic device acquires measurement data via communication, more measurement data can be collected by connecting multiple power supply devices via a communication network. By determining the criteria based on a large amount of measurement data, the diagnostic device can improve the estimation accuracy when estimating the degradation state.

[0018] (4) The diagnostic device described in any one of (1) to (3) above may be provided with an output unit that outputs information prompting maintenance work on the power supply equipment, including replacement of the capacitor, in accordance with the estimation result of the estimation unit.

[0019] According to the diagnostic device described in (4) above, the degradation state or lifespan of the capacitor can be estimated, so that the user can be prompted to perform maintenance work on the power supply equipment, including replacing the capacitor, before the capacitor reaches the end of its lifespan.

[0020] (5) A diagnostic device according to any one of (1) to (4) above may include an output unit that outputs the estimation result from the estimation unit, a reception unit that receives the user's judgment on whether or not to accept the deterioration state of the capacitor, and a presentation unit that presents the user with the maintenance replacement timing of the capacitor according to the received judgment result.

[0021] According to the diagnostic device described in (5) above, the maintenance replacement timing is indicated according to the user's judgment as to whether or not the capacitor's degradation state is acceptable. For example, if the user accepts the capacitor's degradation state, the maintenance replacement timing should be indicated to the user as the later of the estimated lifespan and the rated lifespan. On the other hand, if the user does not accept the degradation state, the maintenance replacement timing should be indicated as the earlier of the estimated lifespan and the rated lifespan.

[0022] (6) In the diagnostic device described in any one of (1) to (5) above, the capacitor may be a capacitor that smooths the power input to the power conversion circuit.

[0023] According to the diagnostic device described in (6) above, the degradation state and lifespan of capacitors used for smoothing applications can be estimated. For example, capacitors used for smoothing applications are connected to power conversion circuits that convert power from DC to DC or AC to DC, and to power conversion circuits that convert power from DC to DC or DC to AC, and are therefore susceptible to degradation due to ripple voltage and ripple current generated in the power conversion circuits. By diagnosing capacitors used for smoothing applications, the degradation state and lifespan of power supply equipment in operation can be estimated, thereby preventing economic losses due to power supply equipment failures.

[0024] (7) The diagnostic method of the present disclosure acquires measurement data relating to the voltage and current values ​​of a capacitor used in the power conversion circuit portion of a power supply device, controls the capacitor so that its voltage control value is substantially constant, and uses the measurement data of the voltage and current values ​​of the capacitor when the output voltage value of the power conversion circuit is near the minimum value and the output current value of the power conversion circuit is near the maximum value to derive the frequency characteristics of the impedance component in the capacitor, calculates the capacitance and equivalent series resistance of the capacitor from the derived frequency characteristics of the impedance component, and uses a computer to perform a process to estimate the degradation state of the capacitor based on the calculated capacitance and equivalent series resistance.

[0025] According to the diagnostic method described in (7) above, measurement data of capacitor voltage and current is acquired from power supply equipment in actual operation via a communication network, and the degradation state of the capacitor is estimated based on the acquired measurement data. Therefore, the diagnostic device can continuously monitor the degradation state of the capacitor over the period until the capacitor degrades (for example, a period of 10 years), which can be useful for planning the maintenance of power supply equipment.

[0026] (8) The computer program of the present disclosure is a computer program that causes a computer to perform the following processes: acquire measurement data relating to the voltage and current values ​​of a capacitor used in the power conversion circuit portion of a power supply device; control the capacitor so that its voltage control value is substantially constant; use the measurement data of the voltage and current values ​​of the capacitor when the output voltage value of the power conversion circuit is near the minimum value and the output current value of the power conversion circuit is near the maximum value to derive the frequency characteristics of the impedance component in the capacitor; calculate the capacitance and equivalent series resistance of the capacitor from the derived frequency characteristics of the impedance component; and estimate the degradation state of the capacitor based on the calculated capacitance and equivalent series resistance.

[0027] The computer program described in (8) above acquires measurement data of capacitor voltage and current from power supply equipment in actual operation via a communication network, and estimates the degradation state of the capacitor based on the acquired measurement data. Therefore, the diagnostic device can continuously monitor the degradation state of the capacitor over the period until the capacitor degrades (for example, a period of 10 years), which can be useful for maintenance planning of power supply equipment.

[0028] The present invention will be described in detail below with reference to the drawings illustrating its embodiments. (Embodiment 1) Figure 1 is a schematic diagram showing an example configuration of a diagnostic system 1 according to Embodiment 1. The diagnostic system 1 according to Embodiment 1 comprises a power supply device 100 to be diagnosed and a diagnostic device 200 for diagnosing the power supply device 100. The diagnostic device 200 is connected to the power supply device 100, for example, via a communication network NW, and diagnoses the power supply device 100 from a remote location. The remote location represents a point far from the power supply device 100. The remote location does not necessarily have to be a point geographically distant from the power supply device 100; it is sufficient if it is a point far enough away that the power supply device 100 cannot be directly operated. Alternatively, the diagnostic device 200 may be built into the power supply device 100. The diagnostic system 1 may also include a user terminal 300 to which the diagnostic results from the diagnostic device 200 are notified.

[0029] The power supply equipment 100 is, for example, a Power Conditioning System (PCS) installed between a solar power generation facility (PV) and the power grid E. The power supply equipment 100 converts the DC power supplied from the solar power generation facility (PV) into DC power of a predetermined voltage, converts the resulting DC power into AC power of a predetermined frequency, and then supplies it to the power grid E.

[0030] Alternatively, the power source for the power supply equipment 100 may be other power generation facilities such as wind power generation facilities or hydroelectric power generation facilities, or it may be a battery storage system such as an ESS (Energy Storage System). The power supply destination for the power supply equipment 100 may be power-consuming facilities such as factories, office buildings, schools, hospitals, restaurants, and airports.

[0031] The power supply equipment 100 may be a bidirectional charger such as a V2X (Vehicle to Load, Home, Grid, etc.) including an electric vehicle power conditioner, or it may be a rectifier, an uninterruptible power supply (UPS), etc.

[0032] The power supply equipment 100 includes, for example, a converter 110, a smoothing circuit 120, an inverter 130, a control unit 140, and a communication unit 150.

[0033] The converter 110 is a power conversion circuit that boosts or steps down the DC power supplied from the photovoltaic (PV) power generation system to a predetermined voltage DC power. The converter 110 is composed of power semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal-Oxide Semiconductor Field-Effect Transistors). A reactor that also serves as a noise filter may be provided between the converter 110 and the PV power generation system.

[0034] The inverter 130 is a power conversion circuit that converts the DC power output from the converter 110 into AC power of a desired frequency. The inverter 130 includes a full-bridge circuit or a half-bridge circuit composed of power semiconductor elements such as IGBTs and MOSFETs. A reactor and a capacitor constituting an LC filter circuit may be provided between the inverter 130 and the power system E.

[0035] A smoothing circuit is provided between the converter 110 and the inverter 130. The smoothing circuit 120 includes a capacitor 120C, one end of which is connected to the output line of the converter 110, and smooths the DC power output from the converter 110. Capacitor 120C is an example of a capacitor used in the power conversion circuit portion of a power supply device. A DC reactor may also be provided in the smoothing circuit 120. The DC reactor is connected between the output line of the converter 110 and the capacitor 120C. The DC reactor is provided to improve the input power factor, reduce harmonics, stabilize the smoothing circuit voltage, etc.

[0036] The control unit 140 controls the operation of the converter 110 and inverter 130 (i.e., the switching operation of the power semiconductor elements) and collects measurement data (time-series data) obtained by measuring the voltage and current values ​​of the capacitor 120C. In order to measure the voltage and current values ​​of the capacitor 120C, the smoothing circuit 120 is provided with a voltage sensor SV for measuring the capacitor voltage and a current sensor SA for measuring the current flowing through the capacitor 120C.

[0037] The control unit 140 collects measurement data of capacitor voltage and current measured by the voltage sensor SV and the current sensor SA. The measurement data is time-series data. Preferably, the voltage and current values ​​included in the measurement data are values ​​at the same time. The control unit 140 outputs the collected measurement data to the communication unit 150. The measurement data collection period and the timing of output to the communication unit 150 can be set as appropriate. In one example, the control unit 140 collects measurement data on a monthly basis and outputs the collected measurement data to the communication unit 150 once a month.

[0038] The communication unit 150 is equipped with a communication interface for communicating with the diagnostic device 200 via the communication network NW. The communication unit 150 transmits measurement data related to the voltage and current values ​​of the capacitor 120C, which are input from the control unit 140, to the diagnostic device 200 via the communication network NW.

[0039] In this embodiment, the power supply unit 100 is configured to include a control unit 140 and a communication unit 150. Alternatively, the control unit 140 and the communication unit 150 may be provided outside the power supply unit 100.

[0040] In this embodiment, the control unit 140 collects measurement data and then transmits it to the diagnostic device 200. Alternatively, the control unit 140 may sequentially upload the measurement data to an external server (not shown) and have the external server collect the measurement data. The external server can then transmit the collected measurement data to the diagnostic device 200 at an appropriate time (for example, once a month).

[0041] The diagnostic device 200 acquires measurement data of capacitor voltage and current from the power supply equipment 100 via the communication network NW. Based on the acquired measurement data of capacitor voltage and current, the diagnostic device 200 diagnoses the power supply equipment 100. Specifically, the diagnostic device 200 estimates the degradation state and lifespan of the capacitor 120C provided in the smoothing circuit 120.

[0042] Figure 2 is a block diagram showing the internal configuration of the diagnostic device 200. The diagnostic device 200 comprises a control unit 201, a storage unit 202, a communication unit 203, an operation unit 204, and a display unit 205.

[0043] The control unit 201 consists of a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and the like. The CPU in the control unit 201 loads various computer programs stored in the ROM or memory unit 202 onto the RAM and executes them, thereby enabling the entire device to function as a diagnostic device 200.

[0044] The control unit 201 is not limited to the above configuration and may be any processing circuit or arithmetic circuit equipped with multiple CPUs, multi-core CPUs, GPUs (Graphics Processing Units), microcontrollers, volatile or non-volatile memory, etc. The control unit 201 may also be equipped with functions such as a timer for measuring the elapsed time from the time a measurement start instruction is given until a measurement end instruction is given, a counter for counting numbers, and a clock for outputting date and time information.

[0045] The storage unit 202 is equipped with a storage device such as an HDD (Hard Disk Drive) or SSD (Solid State Drive). The storage unit 202 stores various computer programs executed by the control unit 201, as well as data necessary for the execution of these computer programs. The computer program stored in the storage unit 202 is an estimation processing program PG for estimating the degradation state of capacitor 120C based on measurement data of capacitor voltage and current measured at specific timings.

[0046] The computer program stored in the memory unit 202 may be provided on a non-temporary recording medium RM on which the computer program is recorded in a readable format. The recording medium RM is a portable memory such as a CD-ROM, USB (Universal Serial Bus) memory, SD (Secure Digital) card, microSD card, or CompactFlash®. In this case, the control unit 201 reads the computer program from the recording medium RM using a reading device (not shown) and installs the read computer program into the memory unit 202. Alternatively, the computer program may be provided via communication. In this case, the control unit 201 can download the computer program via the communication unit 203 and install the downloaded computer program into the memory unit 202.

[0047] The communication unit 203 has an interface for communicating with the communication unit 150 of the power supply device 100 via the communication network NW. The communication unit 203 receives data transmitted from the communication unit 150 (such as measurement data of capacitor voltage and current) via the communication network NW and outputs the received data to the control unit 201. The control unit 201 stores the received data in the storage unit 202. When the control unit 201 inputs data to be sent to the communication unit 150 (for example, instructions to the power supply device 100), the communication unit 203 transmits the input data to the communication unit 150 via the communication network NW.

[0048] The operation unit 204 is equipped with an input interface such as a keyboard and mouse, and accepts user operations. The display unit 205 is equipped with a liquid crystal display device or the like, and displays information that should be notified to the user. In this embodiment, the diagnostic device 200 is configured to include the operation unit 204 and the display unit 205, but the operation unit 204 and the display unit 205 are not essential, and the device may be configured to accept necessary operations via an external computer and transmit information that should be notified to the user to the external computer. An example of an external computer is the user terminal 300.

[0049] The following describes the degradation estimation process performed by the diagnostic device 200. (1) Acquisition of measurement data The control unit 140 of the power supply equipment 100 measures the capacitor voltage and current of the capacitor 120C used in the power conversion circuit section using a voltage sensor SV and a current sensor SA while the power supply equipment 100 is operating in a real environment, and acquires the measurement data. The measurement data is time-series data. Hereinafter, the measured capacitor voltage data will be denoted as V(t) and the measured current data as I(t). The diagnostic device 200 acquires the measured capacitor voltage data V(t) and the measured current data I(t) from the power supply equipment 100 via a communication network NW.

[0050] (2) Derivation of frequency characteristics The control unit 201 of the diagnostic device 200 derives the frequency characteristics of the impedance component in capacitor 120C based on the acquired capacitor voltage measurement data V(t) and current measurement data I(t). For example, the control unit 201 applies a Discrete Fourier Transform (DFT) to each of the capacitor voltage measurement data V(t) and current measurement data I(t) to calculate their respective frequency spectra. The Discrete Fourier Transform is performed on a computer using the Fast Fourier Transform (FFT) algorithm. Alternatively, the control unit 201 may apply a Discrete Cosine Transform (DCT) to calculate the frequency spectrum. In the following, the frequency spectrum of the capacitor voltage is V(ω k ), the frequency spectrum of the current is V(ω k This is written as follows: k can take N values ​​(0, 1, 2, ..., N-1).

[0051] The control unit 201 controls V(ω k ) to I(ω k Divide by ) to get the impedance component Z(ω) of capacitor 120C. k ) is calculated. Since k can take N values, the frequency ω kN impedance components Z(ω) that depend on the k ) can be found.

[0052] Assuming that power conditioner for solar power generation is used as power supply equipment 100, power supply equipment 100 receives a voltage input in the range of, for example, 0 to 660V. When the input voltage to power supply equipment 100 fluctuates over a wide range, the voltage (total voltage) of the DC link capacitor (capacitor 120C in the example of Figure 1), which acts as an intermediate voltage, is often controlled to be constant within a specific voltage range so that the operation of each power conversion circuit does not affect the output (active power, etc.) of power supply equipment 100. For example, if the power conversion circuit has a full-bridge configuration, it is controlled within the range of 360 to 400V. If the power conversion circuit has a half-bridge configuration, it is controlled within the range of 480 to 680V. With such control, the output voltage of power supply equipment 100 will be, for example, within the range of 170 to 230V.

[0053] As described above, the voltage of the DC link capacitor (total voltage) varies greatly depending on the voltage value of the output voltage of each power conversion circuit. Therefore, the measurement data required for the diagnostic method varies depending on the operation of each circuit, including the converter 110 and inverter 130.

[0054] Therefore, the diagnostic device 200 according to the embodiment uses the measurement data of the capacitor voltage and current of the capacitor 120C measured under the following conditions 1 and 2 to determine the impedance component Z(ω k Calculate ).

[0055] Condition 1: The voltage control value of capacitor 120C is controlled to be substantially constant. Condition 2: The output voltage of the power conversion circuit is near the minimum value of the power conversion circuit, and the output current of the power conversion circuit is near the maximum value of the power conversion circuit.

[0056] Condition 1 indicates that the voltage control value of capacitor 120C is controlled to V1 ± ΔV1. For example, assume that the power conversion circuit has a full-bridge circuit configuration and the voltage of the DC link capacitor (capacitor 120C) is constantly controlled within the range of 360 to 400V. With such control, the output voltage of power supply device 100 becomes, for example, a value within the range of 170 to 230V. When the output voltage is controlled to be, for example, 170V, condition 1 indicates that the voltage control value of capacitor 120C is controlled to a value near 360V. V1 is the voltage control value, and ΔV1 is the margin with respect to V1. Both V1 and ΔV1 are set values.

[0057] Condition 2 indicates that the output voltage value of the power conversion circuit is a value of V2 min ±ΔV2, and the output current value of the power conversion circuit is a value of I2 max ±ΔI2. V2 min is the minimum value of the output voltage value in each power conversion circuit, and ΔV2 is the margin with respect to V2 min . I2 max is the maximum value of the output current value in each power conversion circuit, and ΔI2 is the margin with respect to I2 max . V2 min , I2 max are measurement data (time-series data) measured by control unit 140 to control the operations of converter 110 and inverter 130. ΔV2 and ΔI2 are set values. In the embodiment, since the power conversion circuit includes converter 110 and inverter 130, V2 min , I2 max are measured for each of them, and ΔV2 and ΔI2 are set for each of them.

[0058] Under the conditions that satisfy condition 1 and condition 2, the current value of capacitor 120C is measured to be large, so the impedance component Z(ω kThis improves the calculation accuracy when calculating the impedance component Z(ω). Figures 3A and 3B are graphs showing the time change of the ripple current when the input voltage of the power supply device 100 is changed. The vertical axis of each graph represents the current value (A) of the ripple current, and the horizontal axis represents time (s). Figure 3A shows the time change of the ripple current when the input voltage of the power supply device 100 is 400V and the output power of the power conversion circuit is set to its maximum value (100%). Figure 3B shows the time change of the ripple current when the input voltage of the power supply device 100 is 150V and the output power of the power conversion circuit is set to its maximum value (100%). As can be seen from Figures 3A and 3B, even if the output power is the same, the fluctuation of the ripple current can be increased by reducing the input voltage of the power supply device 100, and the impedance component Z(ω) k This can improve the accuracy of the calculation when ) is calculated.

[0059] (3) Calculation of capacitance and equivalent series resistance If capacitor 120C is considered as a series equivalent circuit of the capacitor and the equivalent series resistance (ESR), then the impedance component Z(ω) of capacitor 120C is... k ) is expressed by the following equation 1. Here, C is the capacitance of the capacitor in the equivalent series circuit, and R s This is the equivalent series resistance value.

[0060]

number

[0061] The control unit 201 calculates the impedance component Z(ω) from the measured capacitor voltage data V(t) and the measured current data I(t). k By fitting ) with Equation 1, the capacitance C and equivalent series resistance R can be obtained. s The control unit 201 calculates the capacitance C and equivalent series resistance R in Equation 1. s Using this as a parameter, the impedance component Z(ω) obtained as a measured value is obtained. kBy fitting the capacitor, capacitance C and equivalent series resistance R are obtained. s To find this, existing methods such as the least squares method are used for fitting.

[0062] (4) Estimation of deterioration state The control unit 201 calculates the capacitance C and the equivalent series resistance R. s Based on this, the degradation state of capacitor 120C is estimated. When capacitor 120C degrades, the capacitance C decreases, and the equivalent series resistance R decreases. s It is known that the capacitance C and the equivalent series resistance R increase. Therefore, the control unit 201 controls the capacitance C and the equivalent series resistance R. s Each of them has a threshold (TH C and TH R (Assuming this is the case), the calculated capacitance C is the threshold TH C Less than the calculated equivalent series resistance R s is the threshold TH R If it exceeds this value, it can be assumed that capacitor 120C has deteriorated. Threshold TH for capacitance C C , and equivalent series resistance value R s Threshold TH for R These can be set independently, and the two thresholds TH C ,TH R They may be set to be correlated.

[0063] These threshold TH C ,TH R The capacitance C and equivalent series resistance R are calculated either by human intervention or by learning. In the latter case, the diagnostic device 200 collects measurement data from a power supply device in which a capacitor that has not deteriorated is used in the power conversion circuit, and from a power supply device in which a capacitor that has deteriorated is used in the power conversion circuit. The diagnostic device 200 calculates the capacitance C and equivalent series resistance R from the respective measurement data. s To classify, threshold TH C ,TH R Determine the capacitance C and the equivalent series resistance R. sWhen classifying the values ​​of into groups where the capacitor has degraded and groups where the capacitor has not degraded, existing learning models such as logistic regression, k-nearest neighbors, decision trees, and support vector machines may be used, or statistical methods may be employed.

[0064] In this embodiment, for simplification, the threshold TH C ,TH R The system is configured to estimate the degradation state using [a specific method / function]. Alternatively, the system may be configured to estimate the degradation state using appropriate criteria such as threshold curves or functions.

[0065] The operation of the diagnostic device 200 will be described below. Figure 4 is a flowchart illustrating the procedure performed by the diagnostic device 200. The control unit 201 of the diagnostic device 200 reads the estimation processing program PG from the storage unit 202 and executes it, thereby performing the following processing.

[0066] The control unit 201 of the diagnostic device 200 acquires measurement data V(t) of the capacitor voltage and measurement data I(t) of the current measured by the power supply device 100 via the communication network NW (step S101). The control unit 201 sends a request to transmit measurement data to the power supply device 100 at an appropriate timing and receives the measurement data transmitted from the power supply device 100 in response. Alternatively, the control unit 201 may be configured to receive measurement data that is spontaneously transmitted from the communication unit 150 of the power supply device 100. The control unit 201 temporarily stores the acquired measurement data V(t) of the capacitor voltage and measurement data I(t) of the current in the storage unit 202.

[0067] The control unit 201 performs the following analysis each time it collects measurement data V(t) of the capacitor voltage and measurement data I(t) of the current from the power supply equipment 100 over a predetermined period. The data collection period can be set arbitrarily. For example, if the collection period is set to one month, the control unit 201 may perform the following analysis every month.

[0068] The control unit 201 derives the frequency characteristics of the impedance component in capacitor 120C based on the acquired capacitor voltage measurement data V(t) and current measurement data I(t) (step S102). Specifically, the control unit 201 applies existing methods such as DFT and DCT to the capacitor voltage measurement data V(t) and current measurement data I(t) respectively to derive the respective frequency spectra V(ω k ) and I(ω k Calculate the frequency spectrum V(ω k ) and I(ω k The measurement data V(t) and I(t) used in the calculation of ) are measurement data that satisfy the above conditions 1 and 2. The control unit 201 may acquire output voltage value and output current value data of the power conversion circuit from the power supply equipment 100 in order to identify measurement data that satisfy conditions 1 and 2. The control unit 201 calculates V(ω k ) to I(ω k Divide by ) to get the impedance component Z(ω) of capacitor 120C. k Calculate ).

[0069] The control unit 201 calculates the derived impedance component Z(ω k From the frequency characteristics of ), the capacitance C and equivalent series resistance R of capacitor 120C can be determined. s The control unit 201 calculates the impedance component Z(ω) derived in step S102. k By fitting ) with Equation 1, the capacitance C and equivalent series resistance R can be obtained. s Calculate.

[0070] The control unit 201 calculates the capacitance C and the equivalent series resistance R. s Based on this, the degradation state of capacitor 120C is estimated (step S104). The control unit 201 determines that the calculated capacitance C is below the threshold TH. C It is less than the calculated equivalent series resistance R s is the threshold TH RIf the value is greater than the threshold TH, it is estimated that capacitor 120C is degraded. On the other hand, the control unit 201 determines that the calculated capacitance C is greater than the threshold TH. C The above, or the calculated equivalent series resistance value R s is the threshold TH R Capacitor 120C is presumed not to have degraded if the following conditions are met:

[0071] The control unit 201 outputs information based on the estimation result in step S104 (step S105). For example, if step S104 estimates that capacitor 120C is degraded, the control unit 201 displays text information on the display unit 205 prompting the replacement of capacitor 120C. Figure 5 is a schematic diagram showing an example of the output of the estimation result. Figure 5 shows an example in which text information indicating that capacitor 120C of the power supply device 100 is estimated to be degraded is displayed on the display unit 205.

[0072] If the diagnostic device 200 is equipped with an audio output means, it may be configured to prompt the replacement of capacitor 120C by outputting an audio through the audio output means. Alternatively, the control unit 201 may notify the user terminal 300 via the communication unit 203 of information prompting the replacement of capacitor 120C. If it is estimated in step S104 that capacitor 120C is not degraded, the control unit 201 may display text information indicating that capacitor 120C is not degraded on the display unit 205, or it may omit outputting the information.

[0073] As described above, the diagnostic device 200 according to Embodiment 1 acquires measurement data from the power supply equipment 100 in actual operation and calculates the impedance of the capacitor 120C based on the acquired measurement data. When calculating the impedance of the capacitor 120C, measurement data measured under conditions where the current value is large is used, so the accuracy of impedance calculation can be improved. Based on the calculated impedance, the diagnostic device 200 estimates the degradation state of the capacitor 120C. If the diagnostic device 200 estimates that the capacitor 120C is degraded, it can, for example, notify the user to that effect and encourage the replacement of the capacitor 120C, which can be useful in the maintenance plan for the power supply equipment 100.

[0074] (Embodiment 2) Embodiment 2 describes a configuration in which a machine learning model is used to estimate the degradation state. The overall configuration of the diagnostic system 1 and the internal configuration of the diagnostic device 200 are the same as in Embodiment 1, so their explanation will be omitted.

[0075] The diagnostic device 200 according to Embodiment 2 measures the capacitance C and equivalent series resistance R of the capacitor 120C. s When given input, the degree of degradation of capacitor 120C is estimated using a trained model MD that has been trained to output information regarding the degree of degradation of capacitor 120C.

[0076] Figure 6 is a schematic diagram showing an example configuration of a learning model MD. The learning model MD comprises, for example, an input layer LY1, hidden layers LY2a and LY2b, and an output layer LY3. In the example in Figure 6, the learning model MD is configured to have two hidden layers LY2a and LY2b. Alternatively, the number of hidden layers may be one or three or more. An example of a learning model MD is a DNN (Deep Neural Network). Alternatively, SVM, XGBoost (eXtreme Gradient Boosting), LightGBM (Light Gradient Boosting Machine), etc. may be used.

[0077] Each layer constituting the learning model MD comprises one or more nodes. The nodes in each layer are unidirectionally coupled to the nodes in the preceding and succeeding layers with desired weights and biases. Vector data having the same number of components as the number of nodes in the input layer LY1 is provided as input data for the learning model MD. In Embodiment 2, the input data consists of the capacitance C of capacitor 120C and the equivalent series resistance R s The method for calculating these values ​​is the same as in Embodiment 1, so its explanation will be omitted.

[0078] The data given to each node in the input layer LY1 is passed to the first hidden layer LY2a. In this hidden layer LY2a, the output is calculated using an activation function that includes weight coefficients and biases, and the calculated value is passed to the next hidden layer LY2b, and so on, until the output of the output layer LY3 is obtained.

[0079] The output layer LY3 outputs information regarding the degree of degradation of capacitor 120C. The output format of the output layer LY3 is arbitrary. For example, the output layer LY3 could have 11 nodes, with the first node outputting the probability that the degradation degree is 0% (=P0), the second node outputting the probability that the degradation degree is 10% (=P1), ..., and the eleventh node outputting the probability that the degradation degree is 100% (=P10). Here, a degradation degree of 0% represents a state where capacitor 120C has not degraded at all, and a degradation degree of 100% represents a state where capacitor 120C has completely degraded. Alternatively, the output layer LY3 could have two nodes, with one node outputting the probability that it is degraded and the other node outputting the probability that it is not degraded.

[0080] The learning model MD is trained according to a predetermined learning algorithm, and the internal parameters of the learning model MD, including weight coefficients and biases, are determined. Prior to training, information regarding the degree of degradation of capacitor 120C, as well as the capacitance C and equivalent series resistance R, are obtained. sNumerous datasets including the above are provided. The diagnostic device 200 acquires measurement data of capacitor voltage and current for power supply equipment 100 (power supply equipment 100 with a known degree of degradation) with varying degrees of degradation of capacitor 120C, and the capacitance C and equivalent series resistance R of capacitor 120C are obtained. s The above dataset is prepared by calculating the following. The diagnostic device 200 uses the prepared dataset as training data and learns the learning model MD, including the weight coefficients between nodes and the bias, using algorithms such as backpropagation.

[0081] In the learning phase before operation begins, the diagnostic device 200 trains the learning model MD and stores the trained learning model MD in the storage unit 202. Alternatively, the learning model MD may be trained on an external server, and the trained learning model MD may be stored in the storage unit 202.

[0082] During the operational phase after the start of operation, when the diagnostic device 200 acquires measurement data of capacitor voltage and current from the power supply equipment 100 in operation, it determines the capacitance C and equivalent series resistance R of the capacitor 120C based on the acquired measurement data. s The diagnostic device 200 calculates the capacitance C and the equivalent series resistance R. s The data is input to the learning model MD for calculations, and the degradation state of capacitor 120C is estimated by referring to the information output from the output layer LY3 of the learning model MD. For example, the diagnostic device 200 identifies the node with the highest probability and reads out the corresponding label (degree of degradation) to estimate the degradation state.

[0083] In this embodiment, the learning model MD is stored in the storage unit 202, and the control unit 201 of the diagnostic device 200 performs calculations using the learning model MD. Alternatively, the learning model MD may be installed on an external server, and the calculations using the learning model MD may be performed on the external server by accessing the external server via the communication unit 203. In this case, the control unit 201 of the diagnostic device 200 obtains the capacitance C and equivalent series resistance R from the measurement data acquired from the operating power supply equipment 100. s The calculation can be performed by calculating the value and sending the result to an external server, thereby executing the calculation using the MD learning model.

[0084] As described above, the diagnostic device 200 according to Embodiment 2 estimates the degradation state of capacitor 120C using a learning model MD. In this embodiment, since measurement data is collected from various power supply devices 100 to determine the degree of degradation of capacitor 120C, a learning model MD that is tailored to the actual environment can be constructed, and the degradation state of capacitor 120C can be estimated with high accuracy.

[0085] (Embodiment 3) Embodiment 3 describes a configuration in which the diagnostic device 200 estimates the lifespan of the capacitor 120C. The overall configuration of the diagnostic system 1 and the internal configuration of the diagnostic device 200 are the same as in Embodiment 2, so their explanation will be omitted.

[0086] The diagnostic device 200 according to Embodiment 3 estimates the degradation state of the capacitor 120C at regular intervals (for example, every month) and estimates the lifespan of the capacitor 120C by deriving the time-series change in the degradation state.

[0087] Figure 7 is a graph showing the change in the degree of degradation of capacitor 120C over time. In the graph shown in Figure 7, the horizontal axis represents the elapsed time (months), and the vertical axis represents the degree of degradation. The degree of degradation represents the degradation state of capacitor 120C, estimated using the learning model described in Embodiment 2.

[0088] The control unit 201 of the diagnostic device 200 estimates the degree of degradation of capacitor 120C at regular intervals (for example, every month) and plots it on a graph. The control unit 201 obtains a curve showing the time-series change in the degree of degradation and estimates the number of months in which the curve intersects the life estimation threshold (50% in the example in Figure 7) as the life of capacitor 120C. The control unit 201 displays the estimated lifespan information on the display unit 205. At this time, the control unit 201 may also display the rated lifespan of capacitor 120C along with the estimated lifespan of capacitor 120C. Alternatively, the control unit 201 notifies the user terminal 300 of the estimated lifespan and rated lifespan information via the communication unit 203.

[0089] Alternatively, the control unit 201 may present the user with the maintenance replacement timing for capacitor 120C. In this case, the control unit 201 may receive a decision from the user terminal 300 regarding whether or not the user accepts the current state of deterioration of capacitor 120C, and determine the maintenance replacement timing according to the user's decision. For example, if the user accepts the current state of deterioration of capacitor 120C, the maintenance replacement timing for capacitor 120C can be set to the later of the lifespan of capacitor 120C estimated by the diagnostic device 200 and the rated lifespan of capacitor 120C. On the other hand, if the user does not accept the current state of deterioration of capacitor 120C, the maintenance replacement timing for capacitor 120C can be set to the earlier of the lifespan of capacitor 120C estimated by the diagnostic device 200 and the rated lifespan of capacitor 120C. The diagnostic device 200 can present the determined maintenance replacement timing information to the user by displaying it on the display unit 205 or by notifying the user terminal 300.

[0090] As described above, in Embodiment 3, the lifespan of the capacitor 120C can be estimated, and the maintenance replacement timing can be presented to the user, which can be useful for maintenance planning.

[0091] The disclosed embodiments are illustrative in all respects and not restrictive. The scope of the invention is defined by the claims and includes all modifications in the sense and scope equivalent to the claims. [Explanation of symbols]

[0092] 100 Power equipment 110 Converter 120 Smoothing circuit 130 Inverter 140 Control Unit 150 communication units 200 diagnostic devices 201 Control Unit 202 Storage section 203 Communications Department 204 Operation section 205 Display section 120C Capacitor PG Estimation Processing Program RM recording media

Claims

1. An acquisition unit that acquires measurement data relating to the voltage and current values ​​of capacitors used in the power conversion circuit portion of power supply equipment, A derivation unit that derives the frequency characteristics of the impedance component in the capacitor using measurement data of the voltage and current values ​​of the capacitor when the voltage control value of the capacitor is controlled to be substantially constant, the output voltage value of the power conversion circuit is near the minimum value, and the output current value of the power conversion circuit is near the maximum value, A calculation unit that calculates the capacitance and equivalent series resistance of the capacitor from the frequency characteristics of the derived impedance component, An estimation unit that estimates the degradation state of the capacitor based on the calculated capacitance and equivalent series resistance value, A diagnostic device for power supply equipment, equipped with the following features.

2. The acquisition unit periodically acquires measurement data relating to the voltage and current values ​​of the capacitor. The estimation unit estimates the lifespan of the capacitor by deriving the time-series change in the degradation state of the capacitor based on the capacitance and equivalent series resistance value calculated by the calculation unit. The diagnostic device according to claim 1.

3. A learning unit that learns the criteria for estimating the degradation state of the capacitor. The diagnostic device according to claim 1, comprising:

4. An output unit outputs information prompting maintenance work on the power supply equipment, including the replacement of the capacitor, in accordance with the estimation results from the estimation unit. The diagnostic device according to claim 1, comprising:

5. An output unit that outputs the estimation result from the estimation unit, A receiving unit that accepts the user's judgment as to whether or not to accept the deteriorated state of the capacitor, A display unit that presents to the user the maintenance and replacement timing of the capacitor according to the received judgment result. The diagnostic device according to claim 1, comprising:

6. The capacitor is a capacitor that smooths the power input to the power conversion circuit. The diagnostic device according to claim 1.

7. We acquire measurement data related to the voltage and current values ​​of capacitors used in the power conversion circuit portion of power supply equipment. The voltage control value of the capacitor is controlled to be substantially constant, and the output voltage value of the power conversion circuit is near its minimum value, and the output current value of the power conversion circuit is near its maximum value. Using the measured voltage and current values ​​of the capacitor, the frequency characteristics of the impedance component in the capacitor are derived. From the frequency characteristics of the derived impedance component, the capacitance and equivalent series resistance of the capacitor are calculated. Based on the calculated capacitance and equivalent series resistance, the degradation state of the capacitor is estimated. A diagnostic method that uses a computer to perform the processing.

8. We acquire measurement data related to the voltage and current values ​​of capacitors used in the power conversion circuit portion of power supply equipment. The voltage control value of the capacitor is controlled to be substantially constant, and the output voltage value of the power conversion circuit is near its minimum value, and the output current value of the power conversion circuit is near its maximum value. Using the measured voltage and current values ​​of the capacitor, the frequency characteristics of the impedance component in the capacitor are derived. From the frequency characteristics of the derived impedance component, the capacitance and equivalent series resistance of the capacitor are calculated. Based on the calculated capacitance and equivalent series resistance, the degradation state of the capacitor is estimated. A computer program that causes a computer to perform a process.

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