Power supply system control device, power supply system, power supply system control method, and power supply system control program

Abstract

To stably continue power supply to a load while preventing instantaneous interruption and phase jump, at the time of changeover from a system interconnection operation mode to an autonomous operation mode.SOLUTION: A power supply system controller is a device for controlling a power supply system that comprises an AC power supply and a power storage device and has a system interconnection operation mode and an autonomous operation mode between which changeover is possible. The controller acquires phase angle velocity of output power from the power storage device in the system interconnection operation mode; on the basis of the phase angle velocity, calculates a virtual phase angle of output power from the power storage device after changeover from the system interconnection operation mode to the autonomous operation mode; and, after the changeover, controls a power inverter so that a phase angle of output power of the power storage device in the autonomous operation mode is equal to the virtual phase angle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power supply system control device, a power supply system, a power supply system control method, and a power supply system control program. [Background technology]

[0002] Power supply systems for supplying AC power to loads that consume AC power are known. Such power supply systems include, for example, a commercial grid or an engine generator as an AC power source for generating the AC power. In particular, when handling critical loads such as ships, aircraft, and data centers as the loads to which power is supplied, some power supply systems have uninterruptible power supplies (UPSs) distributed throughout the system to ensure stable power supply even when an unexpected abnormality, such as a power outage, occurs in the AC power source. The UPSs are designed to only handle the power flow from the AC power source to the loads in the power supply system. Therefore, in a non-fault state where no abnormality is occurring in the AC power source, they do not have a function (system stabilization function) for stabilizing the power supply to the load, such as suppressing voltage increases or frequency fluctuations.

[0003] In contrast, a power supply system equipped with a power storage device capable of supplying power obtained by converting DC power from a storage battery to AC power using an inverter can be considered as a distributed power source. In this power supply system, the power storage device can be provided with a system stabilization function in a non-fault state. On the other hand, if the power supply from the AC power source is interrupted due to some abnormality in the AC power source, the power storage device can supply power, allowing the power supply to continue without any disturbance. This type of power supply system is superior in terms of space savings and maintainability of the power supply device compared to a distributed power supply method in which an uninterruptible power supply is installed for each load.

[0004] For example, Patent Document 1 describes the application of virtual synchronous generator control to the inverter in a power supply system that includes a commercial grid, which is an AC power source, and a power storage device that can supply power obtained by converting DC power from a storage battery into AC power using an inverter. In virtual synchronous generator control, when an abnormality occurs in the commercial grid, a circuit breaker is opened autonomously to shut off the commercial grid, and power is supplied to the load from the power storage device without momentary interruption. Furthermore, in Patent Document 2, in a microgrid that is connected to a commercial grid, which is an AC power source, and that includes a power storage device, a load, and an emergency generator, when a power outage occurs in the commercial grid, the system disconnection circuit breaker is immediately opened to disconnect the commercial grid, and the emergency generator is started and connected in parallel to supply power to the load without momentary interruption. Furthermore, Patent Document 3 describes a method for realizing a stable and uninterrupted power supply to important loads in an AC power system that includes a commercial system, which is an AC power source, and two types of distributed power sources, a solar power generation system and a storage battery system, by selecting the load to which power is to be supplied based on the output capacity of the distributed power sources when a power outage occurs in the commercial system. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6006637 [Patent Document 2] Patent No. 6591133 [Patent Document 3] Patent No. 5877480 Summary of the Invention [Problem to be solved by the invention]

[0006] When an abnormality occurs in the AC power supply as described above, the power supply source for the load is switched to a distributed power supply device such as a power storage device. However, this may result in frequency changes or momentary power outages in the power supplied to the load. Specifically, in a non-fault state where no abnormality or other problem occurs in the AC power supply, the distributed power supply device is connected to the AC power supply, and the phase angle of the output voltage or output current is controlled based on the terminal voltage phase of the distributed power supply device (hereinafter referred to as "grid-connected operation mode"). On the other hand, in an emergency operation where an abnormality or other problem occurs in the AC power supply, the distributed power supply itself is controlled at a phase angle based on its own frequency value from the perspective of frequency stabilization (hereinafter referred to as "isolated operation mode"). If the phase of the power supplied to the load is not continuous when switching from the grid-connected operation mode to the isolated operation mode, a phase jump may occur, which may result in load disconnection, frequency fluctuations, or even system collapse.

[0007] In the above-mentioned Patent Document 1, control switching between grid-connected operation mode and stand-alone operation mode is not performed to begin with, and control is targeted at an inverter in a single operation mode (virtual synchronous generator control). Compared to fixed voltage control or fixed frequency control, this type of control has a lower ability to stabilize voltage and frequency, and may lead to grid collapse due to load fluctuations, etc. Furthermore, Patent Documents 2 and 3 are technologies focused on power and energy during power outages, and in the instantaneous value domain (for example, on the order of several hundred microseconds), momentary interruptions and phase jumps (frequency disturbances) may occur, which may lead to load disconnection and grid collapse.

[0008] At least one embodiment of the present disclosure has been made in consideration of the above circumstances, and aims to provide a power supply system control device, a power supply system, a power supply system control method, and a power supply system control program that can stably continue to supply power to a load while preventing momentary power interruptions and phase jumps (frequency disturbances) when switching from a grid-connected operation mode to an independent operation mode. [Means for solving the problem]

[0009] In order to solve the above problem, a power supply system control device according to at least one embodiment of the present disclosure includes: an AC power source; a power storage device that converts DC power from a DC power source into AC power via an inverter; Equipped with a power supply system control device for controlling a power supply system capable of switching between a grid-connected operation mode in which the AC power supply and the power storage device are interconnected to supply power to a load, and an independent operation mode in which power is supplied to the load using the power storage device, a phase angular velocity acquisition unit for acquiring a phase angular velocity of the output power from the power storage device in the grid-connected operation mode; a virtual phase angle calculation unit that calculates a virtual phase angle of output power from the power storage device after switching from the grid-connected operation mode to the independent operation mode, based on the phase angle velocity acquired by the phase angle velocity acquisition unit; and an inverter control unit that controls the inverter so that, after the switching, a phase angle of the output power of the power storage device in the independent operation mode becomes the virtual phase angle; Equipped with.

[0010] In order to solve the above problem, a power supply system according to at least one embodiment of the present disclosure includes: a power supply system control device according to at least one embodiment of the present disclosure; the AC power supply; The power storage device; the load; a switching device capable of switching a connection state of the AC power supply to the load; Equipped with.

[0011] In order to solve the above problem, a power supply system control method according to at least one embodiment of the present disclosure includes: an AC power source; a power storage device that converts DC power from a DC power source into AC power via an inverter; Equipped with A power supply system control method for controlling a power supply system capable of switching between a grid-connected operation mode in which the AC power supply and the power storage device are interconnected to supply power to a load, and an independent operation mode in which power is supplied to the load using the power storage device, the method comprising: acquiring a phase angular velocity of the output power from the power storage device in the grid-connected operation mode; calculating a virtual phase angle of output power from the power storage device after switching from the grid-connected operation mode to the independent operation mode based on the phase angle velocity acquired by the phase angle velocity acquisition unit; controlling the inverter so that a phase angle of the output power of the power storage device in the independent operation mode becomes the virtual phase angle after the switching; Equipped with.

[0012] In order to solve the above problem, a power supply system control program according to at least one embodiment of the present disclosure includes: an AC power source; a power storage device that converts DC power from a DC power source into AC power via an inverter; Equipped with a power supply system control program for controlling a power supply system capable of switching between an interconnected operation mode in which the AC power supply and the power storage device are interconnected to supply power to a load, and an independent operation mode in which power is supplied to the load using the power storage device, To the computer device, acquiring a phase angular velocity of the output power from the power storage device in the grid-connected operation mode; calculating a virtual phase angle of output power from the power storage device after switching from the grid-connected operation mode to the independent operation mode based on the phase angle velocity acquired by the phase angle velocity acquisition unit; controlling the inverter so that a phase angle of the output power of the power storage device in the independent operation mode becomes the virtual phase angle after the switching; is possible. [Effects of the Invention]

[0013] According to at least one embodiment of the present disclosure, it is possible to provide a power supply system control device, a power supply system, a power supply system control method, and a power supply system control program that can stably continue to supply power to a load while preventing momentary power interruptions and phase jumps (frequency disturbances) when switching from a grid-connected operation mode to an independent operation mode. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is an overall configuration diagram of a power supply system according to an embodiment; [Figure 2] 2 is a schematic diagram showing the internal configuration of an inverter control unit in FIG. 1 together with the peripheral configuration. FIG. [Figure 3] 3 is a flowchart illustrating a method for controlling a power supply system according to an embodiment. [Figure 4] 4 shows verification results showing transitions in the phase angle of power supplied to a load before and after switching from a grid-connected operation mode to an independent operation mode by the power supply system control method of FIG. 3. [Figure 5A] FIG. 2 is a diagram illustrating an example of the configuration of a voltage / current control unit for maintaining constant the output voltage of the power storage device in an independent operation mode. [Figure 5B] FIG. 2 is a diagram illustrating an example of the configuration of a voltage / current control unit for maintaining constant the output voltage of the power storage device in an independent operation mode. [Figure 6] 3 is a configuration example of a d-axis voltage output circuit in the voltage / current control unit of FIG. 2. [Figure 7] 7 is a flowchart showing a power supply system control method implemented by a power supply system control device having a voltage and current control unit having the configuration of FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the configurations described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0016] First, a power supply system 1 that is a control target of a power supply system control device 100 according to at least one embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is an overall configuration diagram of a power supply system 1 according to one embodiment.

[0017] The power supply system 1 includes a load 2 that consumes AC power, and an AC power source 4 and a power storage device 6 as distributed power sources capable of supplying AC power to the load 2. The AC power source 4 and the power storage device 6 each constitute a microgrid (partial power system) capable of supplying AC power to the load 2.

[0018] The load 2 is any type of equipment that consumes AC power, such as an important load such as a motor or electric light provided in a ship, an aircraft, or a data center. In this embodiment, for ease of explanation, an example configuration of the power supply system 1 for supplying power to one load 2 is shown, but the number of loads 2 to which power is supplied is not particularly limited.

[0019] The AC power source 4 is one of the distributed power sources included in the power supply system 1. The AC power source 4 is, for example, a diesel engine generator, but may also be a generator that generates electricity using fuel such as a gas engine or gas turbine, or a power supply system such as a commercial system. The AC power source 4 is electrically connected to the load 2 via a first connecting line 8.

[0020] The first connecting line 8 is electrically connected to a branch point 10 via a second connecting line 12 with a power storage device 6, which is another distributed power source included in the power supply system 1. The power storage device 6 includes a secondary battery (storage battery) 6a and an inverter 6b, which is a bidirectional inverter. The secondary battery 6a is a storage battery capable of charging and discharging DC power. For example, a lithium-ion secondary battery, a lead secondary battery, or a nickel-metal hydride secondary battery can be used as the secondary battery 6a. However, a lithium-ion secondary battery is preferable because of its excellent charge / discharge tracking capability. The inverter 6b is an AC-DC converter capable of converting AC to DC and DC to AC. When the secondary battery 6a is discharging, the inverter 6b converts the DC power output from the secondary battery 6a into AC power, thereby supplying power to the load 2. On the other hand, when the secondary battery 6a is charging, the inverter 6b converts AC power input from the AC power source 4 into DC power, thereby charging the secondary battery 6a.

[0021] In this embodiment, for ease of explanation, a configuration example is shown in which the power supply system 1 has one AC power source 4 and one power storage device 6, but the number of AC power sources 4 and power storage devices 6 provided in the power supply system 1 is not limited.

[0022] A circuit breaker 14 is provided in the first connecting line 8 between the AC power source 4 and the branch point 10. In the power supply system 1, the conduction state between the AC power source 4 and the branch point 10 can be switched depending on the open / close state of the circuit breaker 14. For example, in the grid-connected operation mode, an operation mode is performed in a non-fault state in which the AC power source 4 is normal, and a state in which the circuit breaker 14 is closed is detected so that power is supplied from the AC power source 4, and the AC power source 4 and the energy storage device 6 are interconnected to supply power to the load 2. In the isolated operation mode, when an abnormality is detected in the AC power source 4, an open state of the circuit breaker 14 is detected, and in a state in which the AC power source 4 is disconnected from the load 2, power is supplied to the load 2 only from the energy storage device 6.

[0023] In the power supply system 1 having the above configuration, the power supply system control device 100 is provided, thereby realizing the above-mentioned grid-connected operation mode and isolated operation mode.

[0024] The power supply system control device 100 is configured, for example, with a CPU (Central Processing Unit), RAM (Random Access Memory), and a computer-readable recording medium (not shown). A series of processing steps for realizing the various functions described below are recorded in the form of a program on a recording medium, and the CPU reads this program into the RAM and executes information processing and arithmetic processing to realize the various functions described below. Specifically, as shown in FIG. 1, the power supply system control device 100 has, as its functional configuration, an abnormality detection unit 102, an operation mode switching unit 104, and an inverter control unit 106.

[0025] The abnormality detection unit 102 is configured to detect an abnormality in the AC power supply 4. There is no limitation on the method of detecting an abnormality, but for example, when the output voltage of the AC power supply 4 is smaller than a preset reference value, an abnormality in the AC power supply 4 is detected.

[0026] The operation mode switching unit 104 is configured to switch the operation mode in response to the detection result of the abnormality detection unit 102. Specifically, when the abnormality detection unit 102 does not detect an abnormality, the operation mode switching unit 104 implements an interconnected operation mode in which both the AC power source 4 and the power storage device 6 are interconnected and supply power to the load 2 with the circuit breaker 14 in a connected state (closed state). On the other hand, when the abnormality detection unit 102 detects an abnormality, the operation mode switching unit 104 implements an isolated operation mode in which the AC power source 4 is disconnected from the load 2 with the circuit breaker 14 in a non-connected state (open state) and power is supplied to the load 2 only by the power storage device 6.

[0027] The inverter control unit 106 is configured to control the inverter 6b included in the power storage device 6 in the grid-connected operation mode and the independent operation mode. The grid-connected operation mode is an operation mode in which the AC power source 4 and the power storage device 6 are interconnected to supply power, and the inverter control unit 106 controls the inverter 6b so that mainly reactive power is supplied from the power storage device 6. On the other hand, the independent operation mode is an operation mode in which power is supplied only by the power storage device 6, and the inverter control unit 106 controls the inverter 6b so that active power and reactive power are supplied from the power storage device 6.

[0028] FIG. 2 is a schematic diagram showing the internal configuration of the inverse conversion device control unit 106 in FIG. 1 together with the peripheral configuration.

[0029] The inverter control unit 106 includes a dq voltage converter 110 and a dq current converter 112. The dq voltage converter 110 converts the output voltage Vabc of the power storage device 6 into a dq voltage Vdq using the phase angular velocity ω. The dq current converter 112 converts the output current Iabc of the power storage device 6 into a dq current Idq using the phase angular velocity ω. The dq voltage Vdq and the dq current Idq are input to a voltage / current control unit 114, which then outputs a command value C for the inverter 6b.

[0030] The phase angular velocity ω input to the dq voltage converter 110 and the dq current converter 112 can be switched depending on the operation mode of the power supply system 1. In the grid-connected operation mode, the switching unit 118 is controlled so that the output of a phase-locked loop (PLL) 116 (phase angular velocity ω1 in the output power of the power storage device 6) is input as the phase angular velocity ω. On the other hand, in the isolated operation mode, the switching unit 118 is controlled so that the output of the arithmetic circuit 120 (virtual phase angle ω2) is input as the phase angular velocity ω.

[0031] Here, arithmetic circuit 120 includes phase angle velocity acquisition unit 122 and virtual phase angle calculation unit 124. Phase angle velocity acquisition unit 122 is configured to acquire phase angle velocity ω1 in the grid-connected operation mode. In this embodiment, phase angle velocity acquisition unit 122 acquires phase angle velocity ω1 based on the output power of power storage device 6, but phase angle velocity acquisition unit 122 may also acquire a phase angle velocity ω1 (e.g., 60 Hz) stored in advance in a storage unit (not shown).

[0032] The virtual phase angle calculation unit 124 is configured to calculate a virtual phase angle ω2, which is the phase angle when switching from the grid-connected operation mode to the isolated operation mode. The virtual phase angle ω2 is calculated by the following equation using the phase angle rate ω1 acquired by the phase angle rate acquisition unit 122 and the current phase angle θ0 (the phase angle in the grid-connected operation mode immediately before switching to the isolated operation mode). ω2=ω1×t+θ0(1)

[0033] Next, a description will be given of a power supply system control method implemented by the power supply system control device 100 having the above configuration. Fig. 3 is a flowchart showing a power supply system control method according to one embodiment.

[0034] First, as an initial state, the power supply system 1 is operated in a grid-connected operation mode in which the AC power source 4 and the power storage device 6 are interconnected to supply power to the load 2 (step S100). In the grid-connected operation mode, the abnormality detection unit 102 determines whether or not an abnormality has been detected in the AC power source 4 (step S101). The abnormality detection in step S101 is repeatedly performed, thereby monitoring the AC power source 4 in the grid-connected operation mode for abnormalities.

[0035] If it is determined that an abnormality has been detected (step S101: YES), the power supply system control device 100 prepares to switch the operation mode of the power supply system 1 from the grid-connected operation mode to the independent operation mode by the operation mode switching unit 104 by acquiring the phase angle velocity ω1 in the grid-connected operation mode in the arithmetic circuit 120 (step S102), and calculates the virtual phase angle ω2 based on the above equation (1) using the phase angle velocity ω1 as described above (step S103).

[0036] Next, the operation mode switching unit 104 switches from the grid-connected operation mode to the isolated operation mode (step S104). At this time, the inverter control unit 106 controls the inverter 6b so that the phase angle ω after the switching becomes the virtual phase angle ω2 calculated in step S103.

[0037] Figure 4 shows the results of a verification that shows the transition in the phase angle of the power supplied to load 2 before and after switching from grid-connected operation mode to islanded operation mode using the power supply system control method of Figure 3. In this example, switching from grid-connected operation mode to islanded operation mode occurs at time t1, but the phase angle ω remains continuous before and after time t1. This shows that it is possible to stably supply power to the load while suppressing phase jumps (frequency disturbances) when switching from grid-connected operation mode to islanded operation mode.

[0038] In the independent operation mode, the inverter 6b may be controlled by the voltage / current control unit 114 constituting the inverter control unit 106 so as to maintain a constant output voltage of the power storage device 6. In this case, by maintaining a constant output voltage of the power storage device 6 in the independent operation mode, fluctuations in the voltage supplied to the load 2 can be suppressed, and the state of power supply to the load after switching can be quickly stabilized.

[0039] 5A and 5B are diagrams showing an example of the configuration of the voltage / current control unit 114 for maintaining the output voltage of the power storage device 6 constant in the independent operation mode. *As shown in FIG. 5A, the d-axis voltage Vd output from the dq voltage converter 110 and the target d-axis voltage Vd ** The deviation ΔVd between the d-axis voltage Vd and the q-axis current Iq is calculated, and the deviation ΔVd is input to the PI controller 130a. A correction value for the voltage drop of the d-axis voltage due to the output reactor, which is calculated based on the output of the PI controller 130a, the d-axis voltage Vd, and the q-axis current Iq, is added to the d-axis voltage command Vd * will be output.

[0040] 5B shows the q-axis voltage command Vq of the voltage / current control unit 114. * As shown in FIG. 5B, the q-axis voltage Vq output from the dq-voltage converter 110 and the target q-axis voltage Vq ** The deviation ΔVq between the q-axis voltage Vd and the d-axis current Id is calculated, and the deviation ΔVq is input to the PI controller 130b. A correction value for the voltage drop of the q-axis voltage due to the output reactor, which is calculated based on the output of the PI controller 130b, the q-axis voltage Vd, and the d-axis current Id, is added to the q-axis voltage command Vq * will be output.

[0041] The voltage / current control unit 114 calculates the d-axis voltage command Vd * and q-axis voltage command Vq * By controlling the inverter 6b in this way, it becomes possible to maintain the output voltage of the power storage device 6 constant in the self-sustained operation mode. .

[0042] Next, a description will be given of the configuration and control method of the power supply system 1 when switching from the isolated operation mode to the grid-connected operation mode. Fig. 6 shows an example of the configuration of the output circuit of the d-axis voltage Vd in the voltage / current control unit 114 of Fig. 2.

[0043] The voltage / current control unit 114 includes a limiter 140 for limiting the calculation result of the d-axis voltage Vd to fall within a predetermined range (in FIG. 6, the d-axis voltage Vd after passing through the limiter 140 is distinguished by being labeled "Vd'"). The limiter 140 includes a first limiter 140a, a second limiter 140b, and a switching unit 140c. The first limiter 140a has a first range as a limit range for the d-axis voltage Vd, and the second limiter 140b has a second range as a limit range for the d-axis voltage Vd. In the limiter 140, either the first limiter 140a or the second limiter 140b can be selected by the switching unit 140c, and the limit range selected by the switching unit 140c can be imposed on the d-axis voltage Vd. The first limit range is set so that the d-axis voltage Vd is greater than a first value (e.g., 0.2). The second limit range is set so that the d-axis voltage Vd is between a second value (for example, 0.9) that is larger than the first value and a third value (for example, 1.1).

[0044] FIG. 7 is a flowchart showing a power supply system control method implemented by the power supply system control device 100 having the voltage and current control unit 114 having the configuration of FIG.

[0045] As described above, when an abnormality is detected in the AC power supply 4 in the power supply system 1 operating in the grid-connected operation mode, the power supply system 1 switches from the grid-connected operation mode to the independent operation mode, and operates in the independent operation mode (step S200). In the independent operation mode, it is determined whether the AC power supply 4 has been restored (step S201). In step S201, it is determined whether the AC power supply 4 has been restored by monitoring whether the abnormality detected in the AC power supply 4 by the abnormality detection unit 102 has been resolved.

[0046] When it is determined that the AC power supply 4 has been restored (step S201: YES), the operation mode switching unit 104 switches the operation mode of the power supply system 1 from the independent operation mode to the grid-connected operation mode (step S202). In the grid-connected operation mode, power is supplied to the load 2 from both the AC power supply 4 and the power storage device 6, so that the power consumption of the power storage device 6 can be reduced compared to the independent operation mode in which power is supplied to the load 2 only from the power storage device 6. In this way, when the AC power supply 4 is restored, the power consumption of the power storage device 6 can be reduced by quickly returning to the grid-connected operation mode.

[0047] Next, the inverter control unit 106 changes the limit value of the limiter 140 for the d-axis voltage Vd for a predetermined period from the time t2 of switching to the grid-connected operation mode (step S203). Specifically, the first limiter 140a is basically selected in the limiter 140, so that the d-axis voltage Vd is limited to a first range, but for a predetermined period from the time t2 of switching, the switching unit 140c is controlled so that the second limiter 140b is selected in the limiter 140. As a result, for a predetermined period from the time t2 of switching, the d-axis voltage Vd is limited to a second range.

[0048] As a result, when switching from the isolated operation mode to the grid-connected operation mode, the upper and lower limit values ​​of the limit range for the d-axis voltage Vd are set so that the lower limit value is larger for a predetermined time from the switching time t2. This effectively prevents an instantaneous voltage drop from occurring in the load at the switching time t2. As a result, this is effective in stabilizing the frequency and preventing load drop when returning from the isolated operation mode to the grid-connected operation mode.

[0049] After a predetermined period has elapsed since the switching time t2 (step S204: YES), the switching unit 140c selects the first limiter 140a, and the d-axis voltage Vd is returned to the first range (step S205).

[0050] As described above, according to each of the above embodiments, when switching from the grid-connected operation mode to the independent operation mode, the virtual phase angle after switching to the independent operation mode is calculated based on the phase angle velocity in the grid-connected operation mode before switching. This makes it possible to effectively suppress a phase jump (frequency disturbance) in the phase of the power supplied to the load before and after switching from the grid-connected operation mode to the independent operation mode.

[0051] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described embodiments may be combined as appropriate.

[0052] The contents described in each of the above embodiments can be understood, for example, as follows.

[0053] (1) A power supply system control device according to one aspect includes: an AC power source; a power storage device that converts DC power from a DC power source into AC power via an inverter; Equipped with a power supply system control device for controlling a power supply system capable of switching between a grid-connected operation mode in which the AC power supply and the power storage device are interconnected to supply power to a load, and an independent operation mode in which power is supplied to the load using the power storage device, a phase angular velocity acquisition unit for acquiring a phase angular velocity of the output power from the power storage device in the grid-connected operation mode; a virtual phase angle calculation unit that calculates a virtual phase angle of output power from the power storage device after switching from the grid-connected operation mode to the independent operation mode, based on the phase angle velocity acquired by the phase angle velocity acquisition unit; and an inverter control unit that controls the inverter so that, after the switching, a phase angle of the output power of the power storage device in the independent operation mode becomes the virtual phase angle; Equipped with.

[0054] According to the aspect (1) above, when switching from the grid-connected operation mode to the independent operation mode, a virtual phase angle after switching to the independent operation mode is calculated based on the phase angle speed in the grid-connected operation mode before switching. As a result, when switching from the grid-connected operation mode to the independent operation mode, the phase angle of the output power from the power storage device thereafter is controlled to be the virtual phase angle, thereby effectively suppressing the occurrence of a phase jump (frequency disturbance) in the phase of the power supplied to the load before and after switching.

[0055] (2) In another embodiment, in the above embodiment (1), The virtual phase angle ω2 is calculated using the phase angle rate ω1 acquired by the phase angle rate acquisition unit and the phase angle θ0 immediately before switching from the grid-connected operation mode to the independent operation mode, using the following equation: ω2=ω1×t+θ0 It is calculated as follows.

[0056] According to the above aspect (2), when switching from the grid-connected operation mode to the isolated operation mode, the phase angle in the isolated operation mode is controlled so that it becomes a virtual phase angle having the phase angle velocity in the grid-connected operation mode, starting from the phase angle θ0 immediately before switching. This prevents phase jumps (disturbances) during switching, and enables stable power supply to the load before and after the mode switching.

[0057] (3) In another aspect, in the above aspect (1) or (2), The inverter control unit controls the inverter so that the output voltage of the power storage device in the independent operation mode is maintained constant.

[0058] According to the above aspect (3), by maintaining the output voltage of the power storage device constant in the independent operation mode, fluctuations in the voltage supplied to the load can be suppressed, and the state of power supply to the load after switching can be quickly stabilized.

[0059] (4) In another embodiment, in any one of the above (1) to (3), The phase angular velocity acquisition unit acquires the phase angular velocity by actually measuring it based on the output power of the power storage device.

[0060] According to the above aspect (4), by actually measuring the power supplied from the storage device to the load in the grid-connected operation mode (before switching to the independent operation mode), the phase angle velocity, which is also used in calculating the virtual phase angle, can be suitably obtained.

[0061] (5) In another embodiment, in the above embodiment (4), The phase angle velocity acquisition unit calculates the phase angle velocity based on an amount of change in the phase angle of the output power actually measured around one point in time.

[0062] According to the above aspect (5), the phase angle of the output power of the power storage device is actually measured around one point in time, and the phase angle velocity can be suitably calculated based on the amount of change.

[0063] (6) In another embodiment, in any one of the above (1) to (3), The phase angular velocity acquisition unit acquires the phase angular velocity by extracting it from a storage unit.

[0064] According to the above aspect (6), the virtual phase angle of the output power when switching to the isolated operation mode is calculated based on the phase angle speed stored in advance in the storage unit. This allows the phase angle speed of the virtual phase angle to be intentionally specified using the phase angle speed stored in the storage unit. Furthermore, even if the phase angle speed in the grid-connected operation mode before switching is unstable, the virtual phase angle can be suitably calculated in the isolated operation mode.

[0065] (7) In another embodiment, in any one of the above (1) to (6), the inverter control unit includes a limiter for limiting a d-axis voltage output from the inverter, The limiter a first limiter for limiting the d-axis voltage to a first limit range; a second limiter for limiting the d-axis voltage to a second limit range having a lower limit value greater than that of the first limit range for a predetermined time from when the independent operation mode is switched to the grid-connected operation mode; Equipped with.

[0066] According to the above aspect (7), when switching from the isolated operation mode to the grid-connected operation mode, the upper and lower limit values ​​of the limit range for the d-axis voltage are set so that the lower limit value is larger for a predetermined time from the time of switching. This effectively prevents an instantaneous voltage drop from occurring in the load when switching. As a result, this is effective in stabilizing the frequency and preventing load drop when returning from the isolated operation mode to the grid-connected operation mode.

[0067] (8) A power supply system according to one aspect includes: A power supply system control device according to any one of the above (1) to (3), the AC power supply; The power storage device; the load; a switching device capable of switching a connection state of the AC power supply to the load; Equipped with.

[0068] According to the above aspect (8), in the grid-connected operation mode, the AC power supply and the power storage device are connected to the grid to supply power to the load, but if the AC power supply is disconnected by the switching device for some reason, the system switches to the stand-alone operation mode and power is supplied by the power storage device. When such mode switching is performed, according to this system, there is no phase jump (disturbance) in the power supplied to the load, and stable power supply is possible.

[0069] (9) A power supply system control method according to one aspect includes: an AC power source; a power storage device that converts DC power from a DC power source into AC power via an inverter; Equipped with A power supply system control method for controlling a power supply system capable of switching between a grid-connected operation mode in which the AC power supply and the power storage device are interconnected to supply power to a load, and an independent operation mode in which power is supplied to the load using the power storage device, the method comprising: acquiring a phase angular velocity of the output power from the power storage device in the grid-connected operation mode; calculating a virtual phase angle of output power from the power storage device after switching from the grid-connected operation mode to the independent operation mode based on the phase angle velocity acquired by the phase angle velocity acquisition unit; controlling the inverter so that a phase angle of the output power of the power storage device in the independent operation mode becomes the virtual phase angle; Equipped with.

[0070] According to the aspect (9) above, when switching from the grid-connected operation mode to the independent operation mode, a virtual phase angle after switching to the independent operation mode is calculated based on the phase angle speed in the grid-connected operation mode before switching. As a result, when switching from the grid-connected operation mode to the independent operation mode, the phase angle of the output power from the power storage device thereafter is controlled to be the virtual phase angle, thereby effectively suppressing the occurrence of a phase jump (frequency disturbance) in the phase of the power supplied to the load before and after switching.

[0071] (10) A power supply system control program according to one aspect includes: an AC power source; a power storage device that converts DC power from a DC power source into AC power via an inverter; Equipped with a power supply system control program for controlling a power supply system capable of switching between an interconnected operation mode in which the AC power supply and the power storage device are interconnected to supply power to a load, and an independent operation mode in which power is supplied to the load using the power storage device, To the computer device, acquiring a phase angular velocity of the output power from the power storage device in the grid-connected operation mode; calculating a virtual phase angle of output power from the power storage device after switching from the grid-connected operation mode to the independent operation mode based on the phase angle velocity acquired by the phase angle velocity acquisition unit; controlling the inverter so that a phase angle of the output power of the power storage device in the independent operation mode becomes the virtual phase angle; is possible.

[0072] According to the above aspect (10), when switching from the grid-connected operation mode to the independent operation mode, a virtual phase angle after switching to the independent operation mode is calculated based on the phase angle speed in the grid-connected operation mode before switching. As a result, when switching from the grid-connected operation mode to the independent operation mode, the phase angle of the output power from the power storage device thereafter is controlled to be the virtual phase angle, thereby effectively suppressing the occurrence of a phase jump (frequency disturbance) in the phase of the power supplied to the load before and after switching. [Explanation of symbols]

[0073] 1. Power supply system 2. Load 4 AC power supply 6. Energy storage device 6a secondary battery 6b Reverse conversion device 8 1st connection line 10. Fork in the road 12 Second connection line 14 Circuit Breaker 100 Power supply system control device 102 Abnormality detection unit 104 Operation mode switching section 106 Inverter control unit 110 Voltage conversion unit 112 Current conversion unit 114 Voltage and current control section 116 Phase-locked circuit 118 Switching section 120 Arithmetic circuit 122 Phase angular velocity acquisition section 124 Virtual phase angle calculation unit 130a, 130b Controller 140 Limiter 140a First Limiter 140b Second Limiter 140c switching part

Claims

1. An AC power source capable of generating electricity using a rotating machine; a power storage device that converts DC power from a DC power source into AC power via an inverter; Equipped with the AC power supply and the power storage device form a microgrid capable of supplying power to a load, a power supply system control device for controlling a power supply system capable of switching between a grid-connected operation mode in which the AC power supply and the power storage device are interconnected to supply power to the load, and an independent operation mode in which power is supplied to the load using the power storage device, a phase angular velocity acquisition unit for acquiring a phase angular velocity of an output voltage from the inverter in the grid-connected operation mode; a virtual phase angle calculation unit that calculates a virtual phase angle of an output voltage from the inverter device after switching from the grid-connected operation mode to the independent operation mode, based on the phase angle velocity acquired by the phase angle velocity acquisition unit; and an inverter control unit for controlling the inverter so that, after the switching, a phase angle of the output voltage of the inverter in the independent operation mode becomes the virtual phase angle; Equipped with The power supply system control device, wherein the phase angular velocity acquisition unit acquires the phase angular velocity by actually measuring it based on the output voltage of the inverter.

2. The virtual phase angle ω2 is calculated using the phase angular velocity ω1 acquired by the phase angular velocity acquisition unit, time t, and the phase angle θ0 immediately before switching from the grid-connected operation mode to the independent operation mode, using the following equation: ω2 = ω1 × t + θ0 The power supply system control device according to claim 1 , wherein the power supply system control device is configured to calculate the power supply system control time by the following formula:

3. The power supply system control device according to claim 1 , wherein the inverter control unit controls the inverter so that an output voltage of the inverter in the independent operation mode is maintained constant.

4. The power supply system control device according to claim 1 , wherein the phase angle velocity acquisition unit calculates the phase angle velocity based on an amount of change in a phase angle of the output voltage of the inverter that is actually measured around one point in time.

5. the inverter control unit includes a limiter for limiting a d-axis voltage output from the inverter, The limiter a first limiter for limiting the d-axis voltage to a first limit range; a second limiter for limiting the d-axis voltage to a second limit range having a lower limit value greater than that of the first limit range for a predetermined time from when the independent operation mode is switched to the grid-connected operation mode; The power supply system control device according to claim 1 or 2, comprising:

6. The power supply system control device according to claim 1 or 2; the AC power supply; The power storage device; the load; a switching device capable of switching a connection state of the AC power supply to the load; A power supply system comprising:

7. An AC power source capable of generating electricity using a rotating machine; a power storage device that converts DC power from a DC power source into AC power via an inverter; Equipped with the AC power supply and the power storage device form a microgrid capable of supplying power to a load, A power supply system control method for controlling a power supply system capable of switching between a grid-connected operation mode in which the AC power supply and the power storage device are interconnected to supply power to the load, and an independent operation mode in which power is supplied to the load using the power storage device, the method comprising: acquiring a phase angular velocity of an output voltage from the inverter in the grid-connected operation mode; calculating a virtual phase angle of an output voltage from the inverter after switching from the grid-connected operation mode to the independent operation mode based on the phase angle velocity; controlling the inverter so that a phase angle of the output voltage of the inverter in the independent operation mode becomes the virtual phase angle after the switching; Equipped with The power supply system control method, wherein the phase angular velocity is obtained by actual measurement based on the output voltage of the inverter.

8. An AC power source capable of generating electricity using a rotating machine; a power storage device that converts DC power from a DC power source into AC power via an inverter; Equipped with the AC power supply and the power storage device form a microgrid capable of supplying power to a load, a power supply system control program for controlling a power supply system capable of switching between a grid-connected operation mode in which the AC power supply and the power storage device are interconnected to supply power to the load, and an independent operation mode in which power is supplied to the load using the power storage device, To the computer device, acquiring a phase angular velocity of an output voltage from the inverter in the grid-connected operation mode; calculating a virtual phase angle of an output voltage from the inverter after switching from the grid-connected operation mode to the independent operation mode based on the phase angle velocity; controlling the inverter so that a phase angle of the output voltage of the inverter in the independent operation mode becomes the virtual phase angle after the switching; is executable, A power supply system control program, wherein the phase angular velocity is obtained by actual measurement based on the output voltage of the inverter.

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