Electric power system

Abstract

To enable detection of an abnormality in a current sensor even when DC power is relatively small.SOLUTION: An electric power system sets an output current peak target value of an inverter so as to cancel the difference between the voltage of a DC link portion detected by a voltage sensor and a voltage target value, and controls the inverter so as to cancel the difference between the output current of the inverter detected by the current sensor and the output current peak target value. In this case, it is determined whether an abnormality has occurred in the current sensor on the basis of whether a fluctuation amount, which is the difference between the maximum and minimum values of the output current peak target value or the voltage of the DC link portion in a predetermined time, is equal to or greater than a predetermined fluctuation amount.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a power system.

Background Art

[0002] Conventionally, as a diagnostic device for detecting an abnormality in a current sensor between an inverter and an AC motor, when the power difference between the AC power output by the inverter and the DC power output by a DC power supply that supplies power to the inverter is greater than a predetermined power difference threshold value, a device that detects an abnormality in the current sensor has been proposed (see, for example, Patent Document 1). Here, the power difference threshold value is set to a value greater than the power consumption of a specific device that receives power supply from the DC power supply.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described diagnostic device, an abnormality in the current sensor can be detected only when the DC power is somewhat greater than the power consumption of the specific device. For this reason, even when the DC power is relatively small, it is required to be able to detect an abnormality in the current sensor.

[0005] The main object of the power system of the present disclosure is to be able to detect an abnormality in the current sensor even when the DC power is relatively small.

Means for Solving the Problems

[0006] The power system of the present disclosure has taken the following means to achieve the above main object.

[0007] The power system of the present disclosure is a power generation device that generates DC power, A converter that converts the DC power from the power generation device and outputs it to the DC link section; An inverter that converts the DC power of the DC link section into AC power and outputs it to an external load; A voltage sensor that detects the voltage of the DC link section; A current sensor that detects the output current of the inverter; A control device that sets the output current peak target value of the inverter so that the difference between the voltage of the DC link section detected by the voltage sensor and the voltage target value is canceled, and controls the inverter so that the difference between the output current of the inverter detected by the current sensor and the output current peak target value is canceled; A power system comprising: The control device determines whether an abnormality has occurred in the current sensor based on whether a variation amount, which is a difference between the output current peak target value or a maximum value and a minimum value of the voltage of the DC link section over a predetermined time, is equal to or greater than a predetermined variation amount. This is the gist.

[0008] In the power system of the present disclosure, the control device determines whether an abnormality has occurred in the current sensor based on whether a variation amount, which is a difference between the output current peak target value or a maximum value and a minimum value of the voltage of the DC link section over a predetermined time, is equal to or greater than a predetermined variation amount. When an abnormality occurs in the current sensor, due to the influence of the control of the inverter by the control device, the output current peak target value of the inverter and the voltage of the DC link section may vary (pulsate) relatively greatly. Therefore, it is possible to determine whether an abnormality has occurred in the current sensor based on whether the variation amount of the output current peak target value or the voltage of the DC link section is equal to or greater than a predetermined variation amount. In this case, even when the DC power of the power generation device and the DC link section is relatively small, an abnormality in the current sensor can be detected.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0010] Embodiments for carrying out the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of the power system 10 of the present embodiment. The power system 10 of the present embodiment is configured as a system that is installed in a house or the like and supplies power to household loads (external loads) in connection with the utility power supply 1, and includes a power generation device, a fuel cell power conditioner 30, and a control device 50. Here, the power generation device generates DC power, and examples thereof include a fuel cell device 20 and a solar power generation device. Hereinafter, a case where the power system 10 of the present embodiment includes the fuel cell device 20 as a power generation device will be described as an example.

[0011] Although not shown, the fuel cell device 20 includes a fuel cell module including a vaporizer that vaporizes reformed water to generate water vapor, a reformer that steam-reforms a raw fuel gas (e.g., natural gas or LP gas) to generate a fuel gas, a fuel cell stack (solid oxide fuel cell stack) that generates electricity by an electrochemical reaction between the fuel gas and air, etc., and a waste heat recovery device that uses a heat exchanger to convert the waste heat of the fuel cell module into hot water and recover it to a hot water storage tank. Further, as auxiliary equipment 40 for operating the fuel cell device 20, the fuel cell device 20 includes a gas pump that supplies a raw fuel gas to the reformer, a water pump that pumps up reformed water from a water tank and supplies it to the vaporizer, an air pump that supplies air to the fuel cell stack, a circulation pump that circulates hot water in a circulation pipe connecting the above-described heat exchanger and the hot water storage tank, a heater installed in the circulation path, a radiator and a radiator fan installed downstream of the heater in the circulation path, etc. These auxiliary devices operate under the control of a control device 50. Further, a current sensor 22i that detects a current output from the fuel cell stack (output current Ist of the fuel cell stack) is attached to the output terminal of the fuel cell stack, and a voltage sensor 22v that detects a voltage between the terminals of the fuel cell stack (output voltage Vst of the fuel cell stack) is attached between the output terminals of the fuel cell stack.

[0012] The fuel cell power conditioner 30 includes a converter 31, an inverter 32, an LC filter 33, a DC link section 34, and an AC link section 36.

[0013] The converter 31 has switching elements, diodes, reactors, etc. (not shown), and by performing switching control of the switching elements, converts the DC power from the fuel cell device 20 in terms of voltage (step-up) and outputs it to the DC link section 34.

[0014] The inverter 32 has switching elements, diodes, etc. (not shown), and by performing switching control of the switching elements, converts the DC power of the DC link section 34 into AC power of 60 Hz or 50 Hz and supplies it to the AC link section 36 via the LC filter 33.

[0015] The DC link section 34 is connected to the converter 31 and the inverter 32. A smoothing capacitor 35 is connected to the DC link section 34, and a voltage sensor 35v for detecting the voltage between the terminals of the capacitor 35 (the voltage Vlidc of the DC link section 34) is attached between the terminals of the capacitor 35. Further, auxiliary machines 40 and a control device 50 of the fuel cell device 20 are connected to the DC link section 34 directly or via a converter (not shown), and are adapted to operate by receiving the supply of DC power from the DC link section 34.

[0016] The AC link section 36 is connected to the inverter 32 via the LC filter 33, and is connected to an external load together with the utility power supply 1. A current sensor 36i for detecting the current output from the inverter 32 to the AC link section 36 via the LC filter 33 (the output current Iinv of the inverter 32) is attached to the AC link section 36. Also, a voltage sensor 36v for detecting the voltage applied to the AC link section 36 from the inverter 32 via the LC filter 33 (the output voltage Vinv of the inverter 32) is attached to the AC link section 36.

[0017] The control device 50 is configured as a microprocessor centered on a CPU 51. In addition to the CPU 51, it includes a ROM 52 for storing a processing program, a RAM 53 for temporarily storing data, and an input / output port (not shown). Input to the control device 50 via the input port are the output current Ist of the fuel cell stack from the current sensor 22i, the output voltage Vst of the fuel cell stack from the voltage sensor 22v, the voltage Vlidc of the DC link section 34 from the voltage sensor 35v, the output current Iinv of the inverter 32 from the current sensor 36i, the output voltage Vinv of the inverter 32 from the voltage sensor 36v, etc. Output from the control device 50 via the output port are control signals to the switching elements of the converter 31, control signals to the switching elements of the inverter 32, control signals to the auxiliary machines 40 of the fuel cell device 20, control signals to a display device 55 for displaying the operating state of the system, etc.

[0018] In the power system 10 of the present embodiment configured in this way, the CPU 51 of the control device 50 controls the converter 31 and the inverter 32 of the fuel cell power conditioner 30 as follows. Regarding the converter 31, the target duty Dc* of the switching element of the converter 31 is set by feedback control so that the difference between the output power Pinv of the inverter 32 and the power target value Pinv* is canceled, and the switching element of the converter 31 is switched and controlled using the set target duty. Note that the output power Pinv of the inverter 32 is calculated based on the output current Iinv of the inverter 32 detected by the current sensor 36i and the output voltage Vinv of the inverter 32 detected by the voltage sensor 36v. Regarding the inverter 32, first, as shown in Equation (1), the target peak value Iinv_peak* of the output current of the inverter 32 is set by feedback control so that the difference between the voltage Vlidc of the DC link section 34 and the voltage target value Vlidc* is canceled. Here, the target peak value Iinv_peak* of the output current is the maximum value (amplitude) in one cycle of the output current target value Iinv. Subsequently, as shown in Equation (2), a value obtained by multiplying the target peak value Iinv_peak* of the output current of the inverter 32 by the phase θ is set as the output current target value Iinv of the inverter 32. Then, as shown in Equation (3), the target modulation rate Ri* of the inverter 32 is set by feedback control so that the difference between the output current Iinv of the inverter 32 and the output current target value Iinv* is canceled, and the switching element of the inverter 32 is switched and controlled using the set target modulation rate Ri*. Note that the voltage target value Vlidc* is set to a value that decreases as the operation period of the power system 10 becomes longer (the fuel cell device 20 etc. deteriorates). Note that a constant value may be set as the voltage target value Vlidc*.

[0019] Iinv_peak* = PI(Vlildc - Vlidc*) (1) Iinv* = Iinv_peak × sinθ (2) Ri* = PI(Iinv* - Iinv) (3)

[0020] Next, the operation of the power system 10 of this embodiment configured in this way, particularly the abnormality diagnosis process of the current sensor 36i, will be described. FIG. 2 is a flowchart showing an example of an abnormality diagnosis routine executed by the CPU 51 of the control device 50. This routine is repeatedly executed every predetermined time Δt (for example, about several hundred milliseconds to several seconds).

[0021] In the abnormality diagnosis routine, first, the CPU 51 inputs the output power Pst of the fuel cell stack, the output power Pinv of the inverter 32, and the variation amount ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 (step S100). Here, as the output power Pst of the fuel cell stack, a value calculated based on the output current Ist detected by the current sensor 22i and the output voltage Vst detected by the voltage sensor 22v is input. As the output power Pinv of the inverter 32, a value calculated based on the output current Iinv of the inverter 32 detected by the current sensor 36i and the output voltage Vinv of the inverter 32 detected by the voltage sensor 36v is input. The variation amount ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 is calculated as the difference between the maximum value and the minimum value in the target block of the output current peak target value Iinv_peak* of the inverter 32, with each block set every predetermined time Δt. The maximum value and the minimum value in the target block of the output current peak target value Iinv_peak* of the inverter 32 are obtained by setting the output current peak target value Iinv_peak* of the inverter 32 at the start time of the target block as the initial values of the maximum value and the minimum value, updating the maximum value when the output current peak target value Iinv_peak* of the inverter 32 at each time exceeds the maximum value at that time, updating the minimum value when the output current peak target value Iinv_peak* of the inverter 32 at each time is less than the minimum value at that time, and determining the maximum value and the minimum value at the end time of the target block.

[0022] Subsequently, the CPU 51 calculates the power difference ΔP by subtracting the output power Pinv of the inverter 32 from the value obtained by multiplying the output power Pst of the fuel cell stack by the efficiency η (step S110). Then, the CPU 51 determines whether the power difference ΔP is equal to or greater than the threshold value ΔPref (step S120). When it is determined that the power difference ΔP is equal to or greater than the threshold value ΔPref, the CPU 51 determines whether that state continues for a predetermined time Tp (step S130). Here, the efficiency η is the efficiency of the fuel cell power conditioner 30, specifically, the transmission efficiency from the converter 31 to the AC link section 36, and is determined in advance by, for example, experiments or analyses. The threshold value ΔPref is set to a value greater than the maximum power consumption of the auxiliary machine 40 and the entire control device 50 of the fuel cell device 20 connected to the DC link section 34, and is determined in advance by, for example, experiments or analyses. For example, when an abnormality occurs in the current sensor 36i and its detected value (the output current Iinv of the inverter 32) changes from the normal value to the value 0 and is held, the output power Pinv of the inverter 32 becomes the value 0, and the power difference ΔP becomes equal to or greater than the threshold value ΔPref. Therefore, by the process of step S120, it is possible to determine whether there is a possibility that an abnormality has occurred in the current sensor 36i. The predetermined time Tp is a time corresponding to a predetermined multiple of the predetermined time Δt, and is determined in advance by, for example, experiments or analyses.

[0023] When the CPU 51 determines that the power difference ΔP is less than the threshold value ΔPref, or when the CPU 51 determines that the power difference ΔP is equal to or greater than the threshold value ΔPref and determines that that state does not continue for the predetermined time Tp, the CPU 51 sets the value 0 in the abnormality flag F1 (step S140). On the other hand, when the CPU 51 determines that the power difference ΔP is equal to or greater than the threshold value ΔPref and determines that that state continues for the predetermined time Tp, the CPU 51 sets the value 1 in the abnormality flag F1 (step S150). Here, the abnormality flag F1 is a flag indicating the determination result by the first method for determining whether an abnormality has occurred in the current sensor 36i based on whether the power difference ΔP is equal to or greater than the threshold value ΔPref.

[0024] Subsequently, the CPU 51 determines whether or not the amount of change ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 is equal to or greater than the threshold value ΔIinv_peakref (step S160). Here, the threshold value ΔIinv_peakref is a threshold value for determining whether or not a change exceeding the changes that normally occur in the output current peak target value Iinv_peak* of the inverter 32 and the voltage Vlidc of the DC link section 34 due to the above-described feedback control occurs, and is determined in advance by experiments, analysis, etc. When an abnormality occurs in the current sensor 36i and its detected value (output current Iinv of the inverter 32) changes from the normal value to the value 0 and is held, the following events may occur. First, the difference between the output current target value Iinv* based on the output current peak target value Iinv_peak* of the inverter 32 and the output current Iinv of the inverter 32 rapidly increases, and the target modulation rate Ri* of the inverter 32 rapidly increases according to Equation (3). Along with this, the actual output peak current (the maximum value in one cycle of the output current) of the inverter 32 rapidly increases, and the voltage Vlidc of the DC link section 34 rapidly decreases. Then, the output current peak target value Iinv_peak* of the inverter 32 rapidly decreases according to Equation (1), and the target modulation rate Ri* of the inverter 32 rapidly decreases according to Equation (3). Along with this, the actual output peak current of the inverter 32 rapidly decreases, and the voltage Vlidc of the DC link section 34 rapidly increases. Then, the output current peak target value Iinv_peak* of the inverter 32 rapidly increases according to Equation (1), and the target modulation rate Ri* of the inverter 32 rapidly increases according to Equation (3). In this way, the output current peak target value Iinv_peak* of the inverter 32 and the voltage Vlidc of the DC link section 34 can fluctuate (pulse) relatively greatly. Therefore, it is possible to determine whether or not there is a possibility that an abnormality has occurred in the current sensor 36i by the process of step S160.

[0025] When the CPU 51 determines in step S160 that the variation amount ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 is less than the threshold value ΔIinv_peakref, the counter C is counted down by a value of 1 from the previous value and further updated with a lower limit guard at value 0 (step S170). On the other hand, when the CPU 51 determines in step S160 that the variation amount ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 is equal to or greater than the threshold value ΔIinv_peakref, the counter C is counted up by a value of 1 from the previous value and updated (step S180).

[0026] When the CPU 51 updates the counter C, it determines whether the updated counter C is equal to or greater than the threshold value Cref (step S190). Here, the threshold value Cref is determined in advance by experiments, analysis, etc. When the CPU 51 determines that the counter C is less than the threshold value Cref, it sets the value 0 in the abnormality flag F2 (step S200). On the other hand, when the CPU 51 determines that the counter C is equal to or greater than the threshold value Cref, it sets the value 1 in the abnormality flag F2 (step S210). Here, the abnormality flag F2 is a flag indicating the determination result by the second method for determining whether an abnormality has occurred in the current sensor 36i based on whether the variation amount ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 is equal to or greater than the threshold value ΔIinv_peakref. The counter C reaching the threshold value Cref or more corresponds to the frequency of the variation amount ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 being equal to or greater than the threshold value ΔIinv_peakref being equal to or more than a predetermined frequency.

[0027] FIG. 3 is an explanatory diagram for explaining the second method. As shown, when an abnormality occurs in the current sensor 36i and its detected value (output current Iinv of the inverter 32) and thus the output peak current Iinv_peak changes from the normal value to the value 0 and is held (at time t1), the fluctuation of the output current peak target value Iinv_peak* of the inverter 32 becomes large, and the fluctuation amount ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 obtained at the end of each block becomes large. Then, each time this fluctuation amount ΔIinv_peak* is equal to or greater than the threshold value ΔIinv_peakref, the counter C is incremented by a value of 1. When the counter C reaches the threshold value Cref or more (at time t2), the abnormality flag F2 is switched from the value 0 to the value 1.

[0028] Return to the description of FIG. 2. Subsequently, the CPU 51 checks the values of the abnormality flags F1 and F2 (step S220). When the CPU 51 determines that both of the abnormality flags F1 and F2 have the value 0, it ends this routine without determining that an abnormality has occurred in the current sensor 36i. On the other hand, when it determines that at least one of the abnormality flags F1 and F2 has the value 1, it determines that an abnormality has occurred in the current sensor 36i (step S230) and ends this routine.

[0029] As described above, the threshold value ΔPref used in the first method is determined to be a value larger than the maximum power consumption of the auxiliary machine 40 and the entire control device 50 connected to the DC link section 34 of the fuel cell device 20. Therefore, when the value obtained by multiplying the output power Pst of the fuel cell stack by the efficiency η is less than the threshold value ΔPref, in the first method for determining whether an abnormality has occurred in the current sensor 36i based on whether the power difference ΔP is equal to or greater than the threshold value ΔPref, the abnormality of the current sensor 36i cannot be detected regardless of the output power Pinv of the inverter 32. On the other hand, by using the second method for determining whether an abnormality has occurred in the current sensor 36i based on whether the amount of change ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 is equal to or greater than the threshold value ΔIinv_peakref, the abnormality of the current sensor 36i can be detected even when the output power Pst of the fuel cell stack is small. The inventors have confirmed through experiments and analyses that when the actual output power of the inverter 32 is relatively large, the amount of change ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 tends to be small. Therefore, when the actual output power of the inverter 32 is relatively large, the abnormality of the current sensor 36i can be detected more reliably by the first method.

[0030] In the above-described embodiment, the CPU 51 calculates the power difference ΔP by subtracting the output power Pinv of the inverter 32 from the value obtained by multiplying the output power Pst of the fuel cell stack by the efficiency η in the first method. However, the CPU 51 may calculate the power difference ΔP without considering the efficiency η in the first method. Further, the CPU 51 may calculate the power difference ΔP using the power Plidc of the DC link section 34 instead of the output power Pst of the fuel cell stack in the first method. The power Plidc of the DC link section 34 is calculated based on the current Ilidc and voltage Vlidc of the DC link section 34.

[0031] In the above-described embodiment, the CPU 51 determines whether or not an abnormality has occurred in the current sensor 36i based on whether or not the power difference ΔP is equal to or greater than the threshold value ΔPref in the first method. However, the present invention is not limited to this. For example, when the detected value of the current sensor 36i is held at 0 A during the operation of the fuel cell device 20 and the fuel cell power conditioner 30, it may be determined that an abnormality has occurred in the current sensor 36i.

[0032] In the above-described embodiment, the CPU 51 determines that an abnormality has occurred in the current sensor 36i when the counter C reaches a threshold value Cref or more in the second method, that is, when the frequency at which the variation amount ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 becomes equal to or greater than the threshold value ΔIinv_peakref is equal to or more than a predetermined frequency. However, instead of this, when the number of determinations, which is the sum of the number of times the variation amount ΔIinv_peak* is equal to or greater than the threshold value ΔIinv_peakref and the number of times the variation amount ΔIinv_peak* is less than the threshold value ΔIinv_peakref, is equal to or more than a predetermined number of times, and the ratio of the number of times the variation amount ΔIinv_peak* is equal to or greater than the threshold value ΔIinv_peakref to the number of determinations is equal to or more than a predetermined ratio, it may be determined that an abnormality has occurred in the current sensor 36i.

[0033] In the above-described embodiment, the CPU 51 uses the variation amount ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 in the second method. However, instead of this, the variation amount ΔVlidc of the voltage Vlidc of the DC link section 34 detected by the voltage sensor 35v may be used. The variation amount ΔVlidc of the voltage Vlidc of the DC link section 34 is calculated as the difference between the maximum value and the minimum value in the target block of the voltage Vlidc of the DC link section 34 by setting each block every predetermined time Δt.

[0034] In the above-described embodiment, the CPU 51 uses a first method for determining whether or not an abnormality has occurred in the current sensor 36i based on whether or not the power difference ΔP is equal to or greater than the threshold value ΔPref, and a second method for determining whether or not an abnormality has occurred in the current sensor 36i based on whether or not the amount of change ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 is equal to or greater than the threshold value ΔIinv_peakref. However, the CPU 51 may use only the second method without using the first method.

[0035] In the above-described embodiment, the power system 10 shown in FIG. 1 has been described. However, the inverter 32 of the fuel cell power conditioner 30 of the power system 10 may further include an overcurrent detection unit that detects an overcurrent of the inverter 32. In this configuration, when the inverter 32 detects an overcurrent by the overcurrent detection unit, it shuts off the gate of the switching element, and when the detection of the overcurrent by the overcurrent detection unit is canceled, it resumes the switching control of the switching element. Also in this configuration, when an abnormality occurs in the current sensor 36i, the output current peak target value Iinv_peak* of the inverter 32 and the voltage Vlidc of the DC link unit 34 can fluctuate (pulsate) relatively greatly, as in the above-described embodiment. Therefore, it is possible to detect an abnormality in the current sensor 36i by using the amount of change ΔIinv_peak* of the output current peak target value Iinv_peak* of the inverter 32 and the amount of change ΔVlidc of the voltage Vlidc of the DC link unit 34.

[0036] As described above, the embodiments for implementing the present disclosure have been described using the embodiments. However, the present disclosure is not limited to such embodiments, and it goes without saying that the present disclosure can be implemented in various forms without departing from the gist of the present disclosure.

Industrial Applicability

[0037] The present disclosure can be used in the manufacturing industry of power systems and the like.

Explanation of Reference Numerals

[0038] 10 Power system, 20 Fuel cell device (power generation device), 31 Converter, 32 Inverter, 35v Voltage sensor, 36i Current sensor, 50 Control device.

Claims

1. A power generation device that generates direct current power, A converter that converts the direct current power from the power generation device and outputs it to a DC link section, An inverter that converts the direct current power of the DC link section into alternating current power and outputs it to an external load, A voltage sensor that detects the voltage of the DC link section, A current sensor that detects the output current of the inverter, A control device that sets the output current peak target value of the inverter so that the difference between the voltage of the DC link section detected by the voltage sensor and the voltage target value is canceled, and controls the inverter so that the difference between the output current of the inverter detected by the current sensor and the output current peak target value is canceled, A power system comprising: The control device determines whether an abnormality has occurred in the current sensor based on whether a variation amount, which is the difference between the output current peak target value or the maximum and minimum values of the voltage of the DC link section over a predetermined time, is equal to or greater than a predetermined variation amount, Power system.

2. The power system according to claim 1, The control device determines that an abnormality has occurred in the current sensor when the frequency or ratio of the variation amount being equal to or greater than the predetermined variation amount is equal to or greater than a predetermined frequency or a predetermined ratio, Power system.

3. The power system according to claim 2, When the variation amount is equal to or greater than the predetermined variation amount, the control device counts up a counter, and when the variation amount is less than the predetermined variation amount, the control device counts down the counter. When the counter reaches a predetermined counter or more, the control device determines that an abnormality has occurred in the current sensor, Power system.

4. The power system according to claim 1 or 2, The control device performs determination based on a first method that determines whether a power difference between an output related value related to the output of the power generation device and the output power of the inverter is equal to or greater than a predetermined power difference, and a second method that determines whether the variation amount is equal to or greater than the predetermined variation amount. When the determination condition is satisfied by any of the first method and the second method, the control device determines that an abnormality has occurred in the current sensor. When neither the first method nor the second method satisfies the determination condition, the control device determines that no abnormality has occurred in the current sensor, Power system.

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