JP7747950B2 - Power supply device and control method for power supply device - Google Patents

Description

This disclosure relates to a power supply device and a method for controlling a power supply device.

Power supply devices equipped with energy storage devices such as secondary batteries are known for backing up and smoothing the power supply from a power generation system to a power grid. Such power supply devices include a converter that converts the DC power output from the energy storage device into AC power of the required voltage and frequency. When the power supply from the power generation system drops or is cut off, such power supply devices operate to supply the required AC power to the power grid or specific electrical equipment.

International Publication No. 2021/033299

In conventional power supply devices such as those described above, when a short circuit or momentary drop occurs in the power grid, the AC output voltage of the converter drops and the AC output current of the converter increases rapidly. Therefore, the converter is controlled by a combination of voltage control using the AC output voltage and current control using the AC output current.

However, with conventional power supply devices such as those described above, there was a problem in that current control and voltage control could interfere with each other in the event of a short circuit or other accident.

This disclosure was made in consideration of the above-mentioned problems, and aims to provide a power supply device and a power supply device control method that can prevent mutual interference between current control and voltage control in the event of a short-circuit accident or other event.

In order to solve the above problem, a power supply apparatus according to one aspect of the present disclosure includes an energy storage device, a converter that converts the DC output of the energy storage device into an AC output, a current meter that measures the current of the AC output, a voltage meter that measures the voltage of the AC output, and a control unit that controls the converter. The control unit has a voltage control block that references a deviation of the voltage value from a normal voltage value and controls the converter so that the voltage value becomes the normal voltage value, an input cutoff unit that sets the deviation input to the voltage control block to substantially zero when the current value exceeds a first limit value, and a current control block that references the difference between the current value and a predetermined value greater than the first limit value and controls the converter so that the current value becomes the predetermined current value when the current value exceeds the first limit value.

Furthermore, a control method for a power supply device according to one aspect of the present disclosure is a control method for a power supply device including an energy storage device, a converter that converts the DC output of the energy storage device into an AC output, and a control unit that controls the converter, and executes a first control that references a deviation of the voltage value of the AC output from a normal value of the voltage and controls the converter so that the voltage value becomes the normal value, and when the current value of the AC output exceeds a first limit value, simultaneously executes a second control that forcibly sets the deviation in the first control to essentially zero and references the difference between the current value and a predetermined value greater than the first limit value and controls the converter so that the current value becomes the predetermined value.

One aspect of the present disclosure provides a power supply device and a power supply device control method that can prevent mutual interference between current control and voltage control in the event of a short-circuit accident or the like.

1 is a schematic configuration diagram illustrating a power supply device according to an embodiment of the present disclosure and a power system to which the power supply device is applied; FIG. 4 is a diagram illustrating a control logic of a control unit included in the power supply device. 4 is a time chart showing signal waveforms of various parts of the power supply device. FIG. 10 is a waveform diagram showing a specific example of an operating waveform in a power supply device of the comparative example. 5A and 5B are waveform diagrams showing specific examples of operating waveforms in the power supply device.

[Embodiment]
Hereinafter, one embodiment of the present invention will be described in detail.

<Configuration of power system 100 to which power supply device 1 is applied>
Fig. 1 is a diagram showing a power supply device 1 according to an embodiment. Fig. 1 shows the entirety of a power system 100 to which the power supply device 1 is applied. The power supply device 1 is a device that is equipped with an energy storage device 10 and is capable of storing power. Alternating current power (AC output) output by the power supply device 1 is supplied to a plurality of feeders 90.

Each feeder 90 consists of a breaker 91 and a load 92. In each feeder 90, when a short circuit occurs within that feeder 90, the breaker 91 detects that an overcurrent has continued for a predetermined period of time and trips, disconnecting the feeder 90 from the power grid 100.

Although not shown in FIG. 1, the power grid 100 may also include a power generation system that uses natural energy, such as a solar power generation system or a wind power generation system, arranged in parallel with the power supply unit 1. Alternatively, a power generation system that uses fuel, such as a diesel generator or a cogeneration system, may also be arranged in parallel with the power supply unit 1. The power supply unit 1 can be used as a backup for the output of at least one of these power generation systems. In that sense, the power supply unit 1 is also an uninterruptible power supply (UPS).

Specific examples of power systems 100 include isolated power systems on remote islands or in mountainous areas. If such power systems use a power generation system that uses natural energy, applying power supply device 1 equipped with energy storage device 10 can smooth out the power supply that uses natural energy. Alternatively, if such power systems 100 use a power generation system that uses fuel, power supply device 1 can also be used as a backup power source in case of a power generation system failure.

However, specific examples of the power system 100 are not limited to isolated power systems on remote islands or in mountainous areas, but may also be power systems within factories that use natural energy-based power generation systems or other power generation systems. The effects and functions of the disclosed examples of the present invention are similarly achieved even in power systems within factories.

When power supply device 1 according to the embodiment is supplying power to power system 100, even if a short-circuit accident occurs in feeder 90, it operates to continue supplying power to power system 100 without halting operation as much as possible. For ease of understanding, the following description will be written as if only power supply device 1 is supplying power to power system 100. However, as long as power supply device 1 is supplying power to power system 100, the operation of power supply device 1 will be the same even if it is operating in parallel with other power generation systems.

<Configuration of power supply device 1>
As shown in FIG. 1, the power supply device 1 includes an energy storage device 10 , a DC-AC converter 20 (converter), a filter 30 , a current meter 40 , a voltage meter 50 , and a control unit 60 .

The energy storage device 10 is a device that stores input power as energy internally and outputs the stored energy as direct current power (DC output) as needed. The energy storage device 10 may be a device equipped with a secondary battery, such as a lithium-ion battery, a NaS (sodium-sulfur) battery, a redox flow battery, or a lead-acid battery.

However, the energy storage device 10 is not limited to devices equipped with secondary batteries. Any unit capable of storing electrical energy can be used as the energy storage device 10, such as a capacitor, a superconducting power storage unit, a flywheel-type power storage unit, or a compressed air-type power storage unit. Note that the concept of the energy storage device 10 being a device that outputs DC power also includes cases where power is first output internally as AC power, and then converted to DC power using a rectifier circuit, converter, etc.

The DC-AC converter 20 converts the direct current power (DC output) output by the energy storage device 10 into alternating current power (AC output). The DC-AC converter 20 uses PWM (Pulse Width Modulation) in accordance with output commands from the control unit 60 to convert the DC power via the filter 30 into AC power of the required voltage and frequency for use by the power grid 100. The filter 30 is a filter for removing harmonics contained in the output of the DC-AC converter 20. The current meter 40 and voltage meter 50 respectively measure the current and voltage of the alternating current power (AC output) output by the power supply device 1 and transmit this information to the control unit 60.

<Configuration of control unit 60>
Next, the configuration and operation of the control unit 60 will be described in detail with reference to Figures 2 and 3. Figure 2 is a diagram showing the control logic of the control unit 60 included in the power supply device 1. Figure 3 is a time chart showing signal waveforms of each part of the power supply device 1.

The output command output by the control unit 60 to the DC-AC converter 20 is the instantaneous value of the output voltage instructed by the control unit 60. The instantaneous value V sin(ωt) is the product of the phase component sin(ωt) and the amplitude component V. The phase command representing the phase component sin(ωt) is calculated by the phase calculation 902 function block based on the frequency command (corresponding to ω).

The amplitude component V is calculated as an amplitude command. Since the amplitude is non-negative, a limiter 901 is provided to limit signals below 0 when calculating the amplitude command. The output command is generated by multiplying the amplitude command and phase command in a multiplier 903.

In the control unit 60 of this embodiment, during normal operation when no short circuit or voltage drop (of approximately several hundred milliseconds) has occurred on any of the feeders 90, for example, during the period up to time T1 in Figure 3 (the period indicated as "voltage control"), the voltage control block 81 for the DC-AC converter 20 executes a voltage control mode as the first control. Furthermore, when a short circuit or other accident has occurred on any of the feeders 90, for example, during the period from time T1 to time T2 in Figure 3 (the period indicated as "current control"), the control unit 60 executes a current control mode as the second control by the current control block 61 for the DC-AC converter 20.

The voltage control block 81 is a functional block typically found in a control unit that controls the output of a DC-AC converter. The voltage control block 81 includes a voltage controller 802, which receives as input the difference (voltage deviation) between the normal value of the voltage reference amplitude (typically the rated voltage) and the voltage measurement value as a voltage command.

The voltage controller 802 is a functional block that performs, for example, general PI control. The voltage controller 802 calculates its output based on the voltage deviation and the integration of the voltage deviation from the past. If the voltage deviation and the integral of the voltage deviation are zero, the voltage controller 802 continues to calculate a constant value as its output. If the voltage deviation and the integral of the voltage deviation are other than zero, the voltage controller 802 calculates its output so that the voltage deviation approaches zero. In this way, the control unit 60 feedback-controls the DC-AC converter 20 during normal operation (up to time T1 in Figure 3) so that the measured voltage value remains at the normal value.

In the above explanation, a functional block that performs general PI control is used for the voltage controller 802. However, the voltage controller 802 of this embodiment is not limited in any way as long as it is capable of performing feedback control. For example, a functional block that performs other control, such as general P control or differential control, can also be used for the voltage controller 802.

Furthermore, the voltage control block 81 includes a multiplier 801 that multiplies the voltage deviation between the voltage measurement value (AC output voltage value) from the voltage meter 50 and the normal value by the output of the inverter circuit 703. The operation of the inverter circuit 703 will be described later. During the normal operation, a signal of 1 (high level) is input from the inverter circuit 703 to the multiplier 801 of the voltage control block 81, for example, as shown in the period up to time T1 in Figure 3. As a result, during the normal operation, in the voltage control block 81, the voltage deviation is not set to 0, but is input to the voltage controller 802, and feedback control of the DC-AC converter 20 is performed.

Furthermore, as shown in Figure 2, the control unit 60 is configured to add the above-mentioned normal value as the output of the voltage control block 81 and input it to the DC-AC converter 20. However, since the above-mentioned normal value (rated voltage) is a constant value, as a result, under normal circumstances, the DC-AC converter 20 is feedback-controlled by the above-mentioned voltage deviation.

Next, other functional blocks of the control unit 60 will be described. The current control block 61 is provided with a current controller 602, which inputs the difference (current deviation) between the current output upper limit set value and the current measurement value as a current command. Here, in the control unit 60, the current output upper limit set value is a value determined as follows. Note that the current output upper limit set value L1 is indicated by a dotted line in the converter current chart in Figure 3.

When the measured current value is normally smaller than the first limit value, the first limit value is set as the current output upper limit setting. Here, the first limit value is set to a current value that will not damage the DC-AC converter 20 even if such a current is continuously output.

When a short-circuit fault occurs in any of the feeders 90, a fault current flows, causing a sudden increase in the current output by the DC-AC converter 20. This causes the measured current value to exceed the first limit value. When the measured current value exceeds the first limit value, the control unit 60 increases the current output upper limit setting value calculated by the current control block 61 to the second limit value.

The second limit value is a value greater than the first limit value and is selected from values below the short-term overload level of the DC-AC converter 20. The second limit value is set from a current value that will cause the breaker 91 of the feeder 90 in which a short circuit has occurred to trip if an overcurrent continues for a certain period of time. A specific value for the second limit value is approximately 1.5 to 2 times the first limit value.

It is preferable that the control unit 60 gradually changes the current output upper limit setting from the first limit value to the second limit value. This is to ensure stable control of the output voltage of the power supply device 1 in response to changes in the current upper limit value.

Furthermore, if the breaker 91 of the feeder 90 where the short-circuit fault occurred trips, the feeder 90 will be disconnected. This is because the second limit value is set to a value that will cause the breaker 91 of the feeder 90 where the short-circuit fault occurred to trip if an overcurrent (fault current) continues for a certain period of time.

When the location where the short-circuit fault occurred is disconnected from the power grid 100, the outflow of fault current ceases, and the current output by the DC-AC converter 20 suddenly decreases and returns to a value smaller than the first limit value. When the measured current value falls below the first limit value, the control unit 60 sets the first limit value as the current output upper limit setting. In other words, the current output upper limit setting returns to normal.

The current control block 61 includes an effective value calculation 601 functional block to which the current measurement value (AC output current value) from the current meter 40 is input, a current controller 602 to which the difference (current deviation) between the current output upper limit setting value and the current measurement value (if the current measurement value is an instantaneous value, a value proportional to the effective value of the current waveform calculated by the effective value calculation 601 functional block) is input, and a limiter 603 connected to the current controller 602.

The current controller 602 is, for example, a functional block that performs general PI control. If the current deviation and the integral of the current deviation are zero, the current controller 602 continues to calculate 0 as the output. If the current deviation and the integral of the current deviation are other than zero, the current controller 602 calculates the output so that the current deviation approaches zero.

In the above explanation, a functional block that performs general PI control is used for the current controller 602. However, the current controller 602 of this embodiment is not limited in any way as long as it is capable of performing feedback control. For example, a functional block that performs other control, such as general P control or differential control, can also be used for the current controller 602.

The output of the current controller 602 is passed through limiter 603 and, if it is negative, is calculated as the current suppression command (i.e., the output of the current control block 61). Otherwise, due to the action of limiter 603, the current suppression command is 0, and the output of the current controller 602 is not reflected.

Furthermore, the control unit 60 is equipped with a suppression detector 701 to which the output of the current control block 61 is input, a delay circuit 702 to which the output of the suppression detector 701 is input, and an inversion circuit 703 to which the output of the delay circuit 702 is input, and is configured so that the output of the inversion circuit 703 is input to the multiplier 801 of the voltage control block 81.

The suppression detector 701 is a functional block that outputs a signal of 1 (high level) when the current suppression command is negative, i.e., when the output of the current controller 602 is not cut by the limiter 603, and outputs a signal of 0 (low level) otherwise. The delay circuit 702 is a functional block that, when the input signal is inverted from 0 to 1, inverts the signal from 0 to 1 after a predetermined delay time (e.g., 10 ms) and outputs the signal.

At all other times, delay circuit 702 outputs the input signal unchanged. Inversion circuit 703 is a functional block that inverts the input 1 (high level) and 0 (low level) signals and outputs them. The suppression detector 701, delay circuit 702, inversion circuit 703, and multiplier 801 together make up the input blocking unit.

<Operation of power supply device 1>
Next, a description will be given of the operation of the power supply device 1. As described above, during the period up to time T1 in Fig. 3, the DC-AC converter 20 is feedback controlled by the voltage control block 81. At this time, the current output upper limit set value L1 is the first limit value, and the measured current value is equal to or less than the first limit value, so a positive current deviation is input to the current controller 602.

As a result, the current controller 602 outputs a positive signal to increase the output of the DC-AC converter 20, but the output is set to 0 by the action of the limiter 603, and the current suppression command is also set to 0. Therefore, the current control block 61 does not contribute to the control of the DC-AC converter 20. Furthermore, the suppression detector 701, which does not detect the output of the current controller 602, outputs a signal of 0 (low level), which is then passed through the inversion circuit 703 and output to the multiplier 801 as described above.

When a short-circuit fault occurs and the AC output current value exceeds the first limit value at time T1, the current deviation suddenly turns negative, the output of the current controller 602 becomes negative, and a current suppression command is output. The current suppression command is added to the amplitude command, and the output of the DC-AC converter 20 is rapidly suppressed. In this way, the AC output current value (current measurement value) is rapidly suppressed.

Furthermore, the input cutoff unit forces the voltage deviation input to the voltage control block 81 to essentially zero as follows. As a result, the voltage control block 81 no longer substantially contributes to the control of the DC-AC converter 20.

The current suppression command from the current controller 602 is also output to the suppression detector 701. The suppression detector 701 then outputs a signal of 1 (high level) to the delay circuit 702 in accordance with the output (current suppression command) of the current control block 61. The delay circuit 702 outputs the signal received from the suppression detector 701 to the inversion circuit 703. The inversion circuit 703 inverts the level of the signal received from the suppression detector 701 via the delay circuit 702, and outputs it to the multiplier 801 of the voltage control block 81.

As shown in FIG. 3, at time T1, the output from the suppression detector 701 to the delay circuit 702 is switched from low to high, and the output from the inversion circuit 703 to the multiplier 801 is switched from high to low. As a result, at time T1, the input cutoff unit, which includes the suppression detector 701, delay circuit 702, inversion circuit 703, and multiplier 801, forces the voltage deviation input to the voltage control block 81 to essentially zero.

In this way, from time T1 onwards, the DC-AC converter 20 is feedback-controlled by the current control block 61. That is, the control unit 60 controls the DC-AC converter 20 in current control mode (second control mode). As described above, the control unit 60 gradually increases the current output upper limit setting value up to the second limit value, so the AC output current value (measured current value) gradually increases up to the second limit value and then remains constant.

At time T2 in Figure 3, as described above, when feeder 90, which generates its own voltage, is disconnected, the current output by DC-AC converter 20 suddenly decreases to a value smaller than the first limit value, as shown in the converter current in Figure 3. Then, the current deviation suddenly reverses to a positive value, the output of current controller 602 becomes 0, and the current suppression command also becomes 0 due to the action of limiter 603. As a result, from time T2 onwards, current control block 61 no longer contributes to the control of DC-AC converter 20.

As shown in Figure 3, at time T2, the output from the suppression detector 701 to the delay circuit 702 is switched from a 1 (high level) signal to a 0 (low level) signal. Furthermore, due to the function of the delay circuit 702, at time T3, which is the delay period after time T2 in Figure 3, the output from the inversion circuit 703 to the multiplier 801 is switched from a 0 (low level) signal to a 1 (high level) signal.

In other words, during the delay period between time T2 and time T3, the signal from the suppression detector 701 to the inversion circuit 703 is delayed by the delay circuit 702. Therefore, during this delay period, neither the current control block 61 nor the voltage control block 81 contributes to the control of the DC-AC converter 20, and open-loop control is performed based on the voltage reference amplitude value (rated voltage value).

After that, from time T3 onwards, the signal from the inverting circuit 703 to the multiplier 801 becomes a 1 (high level) signal, and the DC-AC converter 20 begins to be controlled by the voltage control block 81.

In other words, in this embodiment, when the value of the AC output current exceeds the first limit value and then drops below the first limit value, the control unit 60 stops control of the DC-AC converter 20 by the current control block 61, and then, after a predetermined delay time has elapsed, causes the input cutoff unit to cancel the cutoff of the voltage deviation input to the voltage control block 81. Then, the control unit 60 causes the voltage control block 81 to perform feedback control.

In the power supply device 1 and control method of this embodiment configured as described above, the control unit 60 has a voltage control block 81 that references the voltage deviation of the AC output voltage from its normal value and controls the DC-AC converter 20 so that the voltage value remains at the normal value. When the AC output current value exceeds a first limit value, the control unit 60 sets the voltage deviation input to the voltage control block 81 to essentially zero, and references the difference between the current value and a predetermined value greater than the first limit value and controls the DC-AC converter 20 so that the current value remains at the predetermined value. This makes it possible to avoid mutual interference between current control and voltage control in the event of a short-circuit accident or the like in this embodiment.

Furthermore, in this embodiment, if the value of the AC output current exceeds the first limit value and then falls below the first limit value, the control unit 60 stops control of the DC-AC converter 20 by the current control block 61 and cancels the cut-off of the input of voltage deviation to the voltage control block 81 by the input cut-off unit. As a result, in this embodiment, after recovery from a short-circuit accident or the like, it is possible to switch from a current control mode for the DC-AC converter 20 by the current control block 61 to a voltage control mode for the DC-AC converter 20 by the voltage control block 81, and to appropriately switch the control mode for the DC-AC converter 20.

In addition, in this embodiment, the control unit 60 adds the output of the current control block 61 to the normal value (voltage amplitude reference value) as the output of the voltage control block 81. As a result, in this embodiment, the control unit 60 performs feedforward control using the normal value, and the AC output voltage can be quickly restored after recovery from a short-circuit accident, etc.

In addition to the above, the control unit 60 can also omit the execution of feedforward control using the normal value as the output of the voltage control block 81, without adding the normal value to the output of the current control block 61. When feedforward control is omitted in this way, the control unit 60 in the power supply unit 1 controls the output voltage (measured voltage value) to gradually return to normal when a short-circuit fault or the like is restored. This effectively prevents the occurrence of transient overcurrents (magnetic inrush currents) in the transformers in the power system 100 that could damage the DC-AC converter 20 of the power supply unit 1, for example, when the output voltage (measured voltage value) suddenly increases.

<Operation when capacitive load is applied>
In this embodiment, when the value of the AC output current exceeds the first limit value, the voltage control mode is stopped and the current control mode is switched to. Therefore, the control unit 60 of this embodiment can suppress overcurrent (inrush current) and the occurrence of overvoltage or voltage drop (momentary voltage drop) by executing the current control mode even when, for example, a capacitor or a transformer is turned on as the load 92 in any of the feeders 90, which causes an overvoltage or voltage drop.

As a comparative example, Figure 4 shows the operation of a power supply device equipped with a control unit having only functions equivalent to the voltage control block 81 of embodiment 1, which is a control unit configuration for controlling a typical DC-AC converter, when a capacitive load is applied. In this comparative example, when a capacitive load such as a capacitor is applied at time T14, as shown in the converter current chart in Figure 4, the AC output current value of the DC-AC converter 20 rises to approximately twice the rated current. In addition, in this comparative example, the effective load voltage also rises to approximately 1.4 times the rated voltage.

In contrast, with the power supply device 1 of this embodiment, as shown in Figure 5, when a capacitive load such as a capacitor is applied at time T4, the increase in the AC output current value of the DC-AC converter 20 can be limited to approximately 1.5 times the rated current, as shown in the converter current chart. Furthermore, in this embodiment, the increase in the effective load voltage can also be limited to approximately 1.08 times the rated voltage.

In the above embodiment, a delay circuit 702 is provided in the input cutoff unit to delay the release of the cutoff of the voltage deviation input to the voltage control block 81 by the input cutoff unit after control of the DC-AC converter 20 by the current control block 61 is stopped. However, this embodiment is not limited to this, and a configuration that does not delay the release of the cutoff of the voltage deviation input to the voltage control block 81 may also be used.

In other words, in the above embodiment, as shown in Figure 3, open-loop control is executed after current control mode, and then voltage control mode is executed. However, a configuration in which the delay circuit 702 is not installed and open-loop control is not executed may also be used. However, performing open-loop control in the control unit 60 is preferable because it can reliably prevent chattering between the operation of the current control block 61 and the operation of the voltage control block 81, and it can easily stabilize the AC output after recovery from a short-circuit accident, etc.

Specifically, the control unit 60 performs open-loop control to prevent fluctuations in the load voltage from being input into the voltage measurement value, causing the voltage controller 802 to fluctuate and output an overcurrent again. By doing so, feedback control is resumed once the load voltage and voltage measurement value have stabilized (i.e., once the vibration has subsided), thereby reliably preventing chattering.

In addition, in the description of the above embodiment, the control of each phase is described as being performed by collective control, without any particular distinction between phases. In this case, the control unit may perform control by adopting the minimum voltage value among each phase and the maximum current value among each phase as the voltage measurement value and current measurement value. Alternatively, the three-phase instantaneous effective value (the root mean square of the instantaneous voltage value of each phase) may be adopted as the current measurement value. However, the control unit may also control each phase separately. In this case, the current upper limit value may be set either collectively or for each phase.

Furthermore, in the description of the above embodiment, the voltage command and frequency command are treated as constant values, particularly rated values, and are not treated as variable values. This corresponds to the case where the power system 100 is operated under so-called constant voltage constant frequency (CFC) operation. However, if the power supply device 1 is operated in conjunction with a power generation system such as a diesel generator, in which the voltage and frequency fluctuate depending on the load state, the voltage command and frequency command may be adjusted in response to such fluctuations.

[Software implementation example]
Each functional block of the power supply device 1 (particularly the control unit 60) may be realized by a logic circuit (hardware) formed on an integrated circuit (IC chip) or the like, or may be realized by software.

In the latter case, the power supply device 1 is equipped with a computer that executes program instructions, which are software that realizes each function. This computer is equipped with, for example, at least one processor (control device) and at least one computer-readable recording medium that stores the program. The object of the present invention is achieved when the processor in the computer reads and executes the program from the recording medium. A CPU (Central Processing Unit), for example, can be used as the processor.

The recording medium may be a "non-transitory tangible medium," such as a ROM (Read Only Memory), tape, disk, card, semiconductor memory, or programmable logic circuit. The computer may also include a RAM (Random Access Memory) on which the program is deployed. The program may also be supplied to the computer via any transmission medium capable of transmitting the program (such as a communications network or broadcast waves). One aspect of the present invention may also be realized in the form of a data signal embedded in a carrier wave, in which the program is embodied through electronic transmission.

〔summary〕
In order to solve the above problem, a power supply device according to one aspect of the present disclosure includes an energy storage device, a converter that converts a DC output of the energy storage device into an AC output, a current meter that measures the current of the AC output, a voltage meter that measures the voltage of the AC output, and a control unit that controls the converter, wherein the control unit has a voltage control block that controls the converter by referring to a deviation of the voltage value from a normal value of the voltage so that the voltage value becomes the normal value, an input cut-off unit that sets the deviation input to the voltage control block to substantially zero when the current value exceeds a first limit value, and a current control block that controls the converter by referring to a difference between the current value and a predetermined value that is greater than the first limit value so that the current value becomes the predetermined value when the current value exceeds the first limit value.

The above configuration provides a power supply device that can prevent mutual interference between current control and voltage control in the event of a short-circuit accident or other event.

In the power supply device according to the above aspect, when the value of the current exceeds the first limit value and then drops below the first limit value, the control unit may stop control of the converter by the current control block and cancel the input cutoff unit's cutoff of the input of the deviation to the voltage control block.

With the above configuration, after recovery from a short-circuit fault or the like, it is possible to switch from current control mode using the current control block for the converter to voltage control mode using the voltage control block for the converter, thereby appropriately switching the control mode for the converter.

In the power supply device according to the above aspect, the control unit may cancel the blocking of the input of the deviation to the voltage control block by the input blocking unit after a predetermined delay time has elapsed since the current control block stopped controlling the converter.

With the above configuration, open-loop control is performed in the control unit, which reliably prevents chattering between the operation of the current control block and the operation of the voltage control block, making it easy to stabilize the AC output after recovery from a short-circuit accident, etc.

In the power supply device according to the above aspect, the control unit may add the output of the voltage control block, the output of the current control block, and the normal value, and input the result to the converter.

With the above configuration, the control unit performs feedforward control using normal values, allowing the AC output voltage to be restored quickly after recovery from a short-circuit accident, etc.

Furthermore, a control method for a power supply device according to one aspect of the present disclosure is a control method for a power supply device including an energy storage device, a converter that converts the DC output of the energy storage device into an AC output, and a control unit that controls the converter, and executes a first control that references a deviation of the voltage value of the AC output from a normal value of the voltage and controls the converter so that the voltage value becomes the normal value, and when the current value of the AC output exceeds a first limit value, simultaneously executes a second control that forcibly sets the deviation in the first control to essentially zero and references the difference between the current value and a predetermined value greater than the first limit value and controls the converter so that the current value becomes the predetermined value.

The above configuration provides a power supply control method that can prevent current control and voltage control from interfering with each other in the event of a short-circuit accident or other event.

This disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the embodiments are also included in the technical scope of this disclosure.

1 Power supply device 10 Energy storage device 20 DC-AC converter (converter)
40 Current measuring instrument 50 Voltage measuring instrument 60 Control unit 61 Current control block 81 Voltage control block 701 Suppression detector (input cutoff unit)
702 Delay circuit (input cutoff section)
703 Inverting circuit (input cutoff section)
801 Multiplier (input cutoff section)

Claims (5)

an energy storage device;
a converter that converts the DC output of the energy storage device into an AC output;
a current meter for measuring the current of the AC output;
a voltage meter for measuring the voltage of the AC output;
a control unit that controls the converter,
The control unit
a voltage control block that controls the converter based on a deviation of the voltage value from a normal value of the voltage so that the voltage value becomes the normal value;
an input cutoff unit that, when the value of the current exceeds a first limit value, forcibly inputs a value substantially equal to 0 as the deviation value to the voltage control block;
a current control block that, when the value of the current exceeds the first limit value, controls the converter by referring to a difference between the value of the current and a predetermined value that is greater than the first limit value, so that the value of the current becomes the predetermined value ;
When the value of the current exceeds the first limit value, control of the converter switches from control by the voltage control block to control by the current control block . The control unit
When the value of the current exceeds the first limit value and then falls below the first limit value,
2. The power supply device according to claim 1, wherein the control of the converter by the current control block is stopped, and the input cutoff unit cancels the cutoff of the input of the deviation to the voltage control block by forcibly inputting substantially zero as the deviation value . The control unit
3. The power supply device according to claim 2, wherein the input cutoff unit cancels the cutoff of the input of the deviation to the voltage control block after a predetermined delay time has elapsed since the control of the converter by the current control block was stopped. The control unit
4. The power supply device according to claim 1, wherein an output of said voltage control block, an output of said current control block, and said normal value are added together and input to said converter. an energy storage device;
a converter that converts the DC output of the energy storage device into an AC output;
a control unit that controls the converter,
executes a first control that controls the converter by referring to a deviation of a voltage value of the AC output from a normal value of the voltage so that the voltage value becomes the normal value;
When the value of the current of the AC output exceeds a first limit value,
The value of the deviation in the first control is forcibly set to substantially 0,
and performing a second control to control the converter by referring to a difference between the value of the current and a predetermined value that is greater than the first limit value, so that the value of the current becomes the predetermined value.
A control method for a power supply device , wherein control of the converter is switched from control that causes the voltage value to be the normal value to control that causes the current value to be the predetermined value.