Electric power conversion device and control method of electric power conversion device

Abstract

To reduce a power loss in a self-sustained operation of an electric power conversion device having a power storage device.SOLUTION: An electric power conversion device having a power storage device comprises: an operation determination part that determines whether or not it is in a self-sustained operation state; a power calculation part that calculates power stored or output by the power storage device, and determines whether or not the power is stored in the power storage device; an effective power command value setting part that receives an effective power value, and determines an effective power command value from the received value and effective power calculated by the power calculation part; and a main circuit that outputs power on the basis of the effective power command value determined by the effective power command value setting part. When the operation determination part determines that it is in the self-sustained operation state, if the power calculation part detects the power storage in the power storage device, the effective power command value setting part changes the value to the effective power command value where the power is not stored in the power storage device.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power conversion device and a control method for the power conversion device. [Background technology]

[0002] A power supply system consisting of a plurality of power generation facilities including a power storage facility having a power storage device and a power converter, the power supply system having a voltage measurement means for measuring a voltage of the power supply system, a frequency measurement means for measuring a frequency of the power supply system, a power measurement means for measuring an active power and a reactive power at an output terminal of the power storage facility, and a system control device, the system control device comprising: a first proportional calculator for proportionally calculating a deviation between an active power command value and the active power measured by the power measurement means; and a frequency command value calculation unit having a first adder for adding a reference frequency to an output of the first proportional calculator to calculate a frequency command value; There is a power conversion device for a combined power generation system that includes an internal phase difference angle calculation unit that calculates an internal phase difference angle by integrating the deviation between a command value and the frequency measured by the frequency measurement means, an internal electromotive voltage command value calculation unit that has a second proportional calculator that proportionally calculates the deviation between a reactive power command value and the reactive power measured by the power measurement means, and a second adder that adds a reference voltage to the output of the second proportional calculator to calculate an internal electromotive voltage command value, and a current command value calculation unit that calculates a command value for the output current of the power converter from the internal phase difference angle, the internal electromotive voltage command value, and the voltage measured by the voltage measurement means, and outputs the command value for the output current to control the power converter (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO13 / 008413 Summary of the Invention [Problem to be solved by the invention]

[0004] The power conversion device for a combined power generation system described above supplies a power converter that does not require a change in the control method in grid interconnection or the like, thereby making it possible to build an independent power supply system that is easy to handle.

[0005] However, while the power conversion device for the combined power generation system outputs the active power according to the command value during grid-connected operation, during independent operation the output of the power conversion device for the combined power generation system is determined by the power consumption of the load. Therefore, when switching from grid-connected operation to independent operation, if independent operation is started using the command value of the active power during grid-connected operation, the actual active power output by the power conversion device for the combined power generation system will deviate from the command value.

[0006] When multiple power conversion devices for a combined power generation system are operated in parallel, there is a problem that charging power conversion devices and discharging power conversion devices for the combined power generation system are mixed together, resulting in losses due to the exchange of power between the power conversion devices for the combined power generation system.

[0007] An object of the present invention is to provide a power conversion device including a power storage device that reduces power loss during stand-alone operation. [Means for solving the problem]

[0008] The object of the present invention is achieved by a power conversion device equipped with a power storage device, comprising an operation determination unit which determines whether the power storage device is in an autonomous operation state, a power calculation unit which calculates the power stored or output by the power storage device and determines whether power is being stored in the power storage device, an active power command value setting unit which receives an active power value and determines an active power command value from the received value and the active power calculated by the power calculation unit, and a main circuit which outputs power based on the active power command value determined by the active power command value setting unit, wherein when the operation determination unit determines that the power conversion device is in an autonomous operation state, the active power command value setting unit changes the active power command value to one that does not store power in the power storage device when the power calculation unit detects that power is being stored in the power storage device. Effect of the Invention

[0009] According to the present invention, it is possible to reduce power loss during stand-alone operation of a power conversion device equipped with a power storage device. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a configuration of a power conversion device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing the configuration of a phase command generating unit according to the first embodiment of the present invention. [Diagram 3] 4 is a diagram showing the relationship between an active power command value, active power, and an angular frequency change amount command in the first embodiment of the present invention. FIG. [Figure 4] FIG. 1 is a block diagram showing a system configuration according to a first embodiment of the present invention. [Diagram 5] 5 is a graph showing the relationship between an active power command value, active power, and an angular frequency change amount command in the system configuration example of the first embodiment of the present invention. [Figure 6] 4 is a flowchart of an active power command value updating method for the power conversion device according to the first embodiment of the present invention. [Figure 7] 5 is a graph showing a time change in active power and a time change in an angular frequency change amount command of the power conversion device according to the first embodiment of the present invention. [Figure 8] 5 is a graph showing the relationship between the active power command value, the active power, and the angular frequency change amount command when the load power consumption fluctuates in the system configuration example of the first embodiment of the present invention. [Figure 9] FIG. 6 is a block diagram showing the configuration of a power conversion device according to a second embodiment of the present invention. [Figure 10] FIG. 11 is a block diagram showing a system configuration according to a second embodiment of the present invention. [Figure 11] 10 is a graph showing the relationship between an active power command value, an angular frequency command, and an update determination angular frequency in a system configuration example according to a second embodiment of the present invention. [Figure 12] 10 is a flowchart of an active power command value updating method for a power conversion device according to a second embodiment of the present invention. [Figure 13] 10 is a graph showing the relationship between an active power command value, active power, and an angular frequency change amount command in a system configuration example according to a second embodiment of the present invention. [Figure 14] 10 is a graph showing the relationship between an active power command value, active power, and an angular frequency change amount command in a system configuration example according to a second embodiment of the present invention. [Figure 15] 11 is a graph showing the relationship between an active power command value, an angular frequency command, and an update determination angular frequency in the third embodiment of the present invention. [Figure 16] 11 is a graph showing a relationship between an active power command value, active power, and an angular frequency change amount command in the third embodiment of the present invention. [Figure 17] 11 is a graph showing a relationship between an active power command value, active power, and an angular frequency change amount command in the third embodiment of the present invention. [Figure 18] FIG. 11 is a block diagram showing a system configuration according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following examples. Those skilled in the art can make various additions and modifications within the scope of the present invention. EXAMPLES

[0012] FIG. 1 shows an example of the configuration of a power conversion device according to a first embodiment of the present invention.

[0013] The power conversion device 1 includes a main circuit 2 which is a power supply unit, a control unit 3 which controls the power and phase to be supplied, and an AC filter 4 which adjusts the waveform of the power to be supplied. The main circuit 2 is, for example, a three-phase full-bridge inverter, and the AC end of the main circuit 2 is connected to an AC system 5 and an AC load 6 via an AC filter 4 and a private line 52. The AC system 5 is, for example, 50 Hz, three-phase 200 V, and the AC load 6 is, for example, equipment owned by a consumer, such as an air conditioner.

[0014] Note that the AC load 6 is described as a single load, but in reality, multiple AC loads may be connected. The AC filter 4 is composed of an inductor and an X capacitor. A connection point relay 51 is installed at the connection point of the AC system 5 so that the power conversion device 1 and the AC load 6 can be disconnected from the AC system 5.

[0015] The DC end of the main circuit 2 is connected to a power storage device 7. The power storage device 7 is, for example, a secondary battery such as a lithium ion battery, a nickel-metal hydride battery, or a lead storage battery, or a capacitor. Note that the power storage device 7 may also be a device that can store energy in a form other than electric power, such as CAES (Compressed Air Energy Storage), pumped storage power generation, gravity power generation, or a flywheel, and a device that converts the energy into electric power.

[0016] A voltage meter 21 is provided on the AC system 5 and AC load 6 side of the AC filter 4, and a current meter 22 is provided on the main circuit 2 side of the AC filter 4. The control unit 3 obtains the AC voltage measurement value Vout from the voltage meter 21 and the AC current measurement value Iout from the current meter 22.

[0017] The control unit 3 includes a power calculation unit 31, a phase command generation unit 32, an active power command value setting unit 33, a reactive power command generation unit , a reactive power control (AQR) unit 35, and a main circuit control unit .

[0018] The power calculation unit 31 calculates the active power Pout (in this embodiment, the power flow that charges the DC power supply 7 is considered to be positive) and the reactive power Qout (in this embodiment, the delay is considered to be positive) output by the power conversion device 1 from the AC voltage measurement value Vout and the AC current measurement value Iout.

[0019] The phase command generating unit 32 generates a phase command θref using the active power Pout calculated by the power calculating unit 31 and the active power command value Pref output by the active power command value setting unit 33 .

[0020] FIG. 2 shows a configuration example of the phase command generation unit in the first embodiment of the present invention. In the phase command generation unit 32, first, the active power command value Pref and the active power Pout are input to the subtractor 321 to obtain the deviation Pout - Pref.

[0021] This is input to the proportional controller 322 with a gain Kp to calculate the angular frequency change amount command Δωref’. When illustrated, it is as shown in FIG. 3, and the angular frequency change amount command Δωref’ is determined by the droop control that inputs the deviation of the active power. The slope of the droop characteristic of this active power - angular frequency change amount command is the gain Kp, TIFF2025014214000002.tif6150

[0022] and is expressed as such. When Pout < Pref, Δωref’ < 0, and by decreasing the angular frequency, Pout is increased (increase in charging power or decrease in discharging power). Also, when Pout > Pref, Δωref’ > 0, and Pout is decreased (decrease in charging power or increase in discharging power).

[0023] In this embodiment, instead of using this angular frequency change amount command Δωref’ as it is, it is input to the virtual inertia imparting filter 323.

[0024] The virtual inertia imparting filter 323 is, for example, a first-order lead-lag filter. By determining its time constant using the unit inertia constant or unit damping constant of the synchronous generator, an angular frequency change amount command Δωref is output, which virtually imparts the inertia of the synchronous generator to Δωref’.

[0025] With this virtual inertia imparting filter 323, Δωref’, which instantaneously changes in a stepwise manner when the deviation Pout - Pref changes in a stepwise manner, can be gently changed, and an inertial angular frequency change can be realized.

[0026] This post-inertia-imparting angular frequency change command Δωref and the reference angular frequency ω0 (in this embodiment, the reference frequency is set to 50 Hz and the reference angular frequency is set to 2π×50 rad / s) are input to an adder 324 to obtain an angular frequency command ωref. Then, the angular frequency command ωref is input to an integrator 325 for integration to generate a phase command θref. The generated phase command θref is output to the main circuit control unit 36.

[0027] The active power command value setting unit 33 can receive the active power value Pref' from a higher-level command device 8 (e.g., an energy management system) of the power conversion device 1 that is external to the power conversion device 1, by wired communication or wireless communication. At this time, the active power command value Pref is output to the phase command generating unit 32 as the active power command value Pref using the received active power value Pref'. The reception frequency can be set arbitrarily, for example, at a one-minute cycle. Non-periodic reception is also possible.

[0028] A reactive power command generating unit 34 generates a reactive power command Qref by multiplying a deviation V0-Vout between a rated voltage V0 (e.g., 200V) and an AC voltage measurement value Vout by a proportional gain Kq (Kq>0). Then, a reactive power control (AQR) unit 35 generates a voltage command Vref by PI control of the deviation Qref-Qout between this reactive power command Qref and the reactive power Qout calculated by the power calculation unit 31. The generated voltage command Vref is output to a main circuit control unit 36.

[0029] The main circuit control unit 36 ​​generates gate signals for the switching elements of the main circuit 2 by PWM (Pulse Width Modulation) control using the phase command θref and the voltage command Vref, and drives the main circuit 2.

[0030] As a result, the power conversion device 1 can operate in a grid-connected state with virtual inertia. Since the power conversion device 1 is driven using the phase command θref and the voltage command Vref, the power conversion device 1 operates as a voltage source and can operate independently when the AC grid 5 is disconnected.

[0031] 4 is a block diagram showing an example of a system configuration of a power conversion device according to the first embodiment of the present invention. In this embodiment, a power conversion device 101 and a power conversion device 102 are connected in parallel to an AC load 6 via a private line 52.

[0032] In this embodiment, the AC load 6 is a load that does not generate regeneration as a whole, and the power consumption is Pload (Pload>0). The configurations of the power conversion device 101 and the power conversion device 102 are the same as that of the power conversion device 1. Also, it is assumed that the gains Kp and Kq used in the power conversion device 101 and the power conversion device 102 are the same.

[0033] It is assumed that the upper level command device 8 of the power conversion device communicates with the power conversion device 101 and the power conversion device 102, and transmits Pref1' (Pref1'>0) as the active power value Pref' to the power conversion device 101, and Pref2' (Pref2'>Pref1') as the active power value Pref' to the power conversion device 102.

[0034] Then, the active power command value setting units 33 of the power conversion devices 101 and 102 generate active power command values ​​Pref1 and Pref2, respectively.

[0035] FIG. 5 is a graph showing the relationship between the active power command value, the active power, and the angular frequency change amount command in the system configuration example of the first embodiment of the present invention, and shows the droop characteristics of the power conversion device.

[0036] Here, Pref1=Pref1', Pref2=Pref2'. At this time, the relationship between the active power command value and the angular frequency change amount command is shown in Fig. 5. Point 0 enclosed in a circle is the operating point of power conversion device 101 and power conversion device 102 when they are operating in interconnected mode.

[0037] The droop characteristic of the power conversion device 101 is the solid line a, and the droop characteristic of the power conversion device 102 is the solid line b. The AC power system 5 supplies power to the power conversion device 101 and the power conversion device 102 by Pref1 and Pref2 respectively, and supplies power to the AC load 6 by Pload. That is, if the power supplied by the AC power system 5 is Pgrid, then Pgrid = Pref1 + Pref2 + Pload.

[0038] Here, when an accident, power outage, etc. occur in the AC power system 5, the tie-point relay 51 becomes open, and the power conversion device 101 and the power conversion device 102 shift to independent operation within the self-owned line 52 and supply power to the AC load 6.

[0039] At this time, regardless of the values of Pref1 and Pref2, the power conversion device 101 and the power conversion device 102 output the total power consumption Pload of the AC load 6. That is, if the actual active power of the power conversion device 101 and the power conversion device 102 after the shift to independent operation is Pout1 and Pout2, then Pout1 + Pout2 = -Pload.

[0040] Since the power conversion device 101 and the power conversion device 102 are operating in parallel within the independent operation system, the angular frequency change amount command Δωref’ of the operating point after the shift to independent operation takes a common value. Point 1 in Fig. 5 is the operating point immediately after the shift to independent operation.

[0041] Let the actual active power of the power conversion device 101 and the power conversion device 102 at this operating point 1 be represented as Pout1_1 and Pout2_1. At the operating point 1, Pout1_1 < 0 < Pout2_1 and Pout1_1 + Pout2_1 = -Pload, and the power conversion device 101 is discharging and the power conversion device 102 is charging to supply power to the AC load 6.

[0042] In this state, power can be supplied to the AC load 6, but power transfer occurs between the power conversion devices. Due to this power transfer, additional power conversion losses occur.

[0043] Therefore, control is performed so as to supply power to the AC load 6 without power exchange between the power conversion apparatus 101 and the power conversion apparatus 102. Since Pout1+Pout2=-Pload<0, at least one of the power conversion apparatus 101 and the power conversion apparatus 102 needs to discharge. Therefore, the charging power conversion apparatus is controlled so as not to charge, thereby preventing power exchange between the power conversion apparatus 101 and the power conversion apparatus 102. In this embodiment, the charging power conversion apparatus 102 is controlled.

[0044] FIG. 6 is a flowchart of the method for updating an active power command value of the power conversion device according to the first embodiment of the present invention.

[0045] With this method, the power conversion device no longer needs to receive an angular frequency command value from an external source to charge or discharge; instead, the device changes the active power command value based on ωcheck and information on whether it is charging or discharging itself, making it possible to control the amount of charge and discharge.

[0046] The upper command device 8 may calculate an active power command value based on measured values ​​such as the charge / discharge amount for each power conversion device and the power consumption of the AC load, and transmit the calculated active power command value to each power conversion device. However, if the power consumption of the AC load changes frequently or if a large number of power conversion devices are connected, the upper command device 8 would need to have real-time processing capabilities, which is not practical.

[0047] Hereinafter, the power conversion device may be referred to as a PCS. Fig. 6 is executed in a calculation cycle (for example, 100 microseconds) in a control unit of a power conversion device having this method. Hereinafter, the control of the power conversion device 102 and changes in the operating points of the power conversion devices 101 and 102 will be described with reference to Figs. 5 and 6.

[0048] First, when the power conversion device receives a new active power value Pref' from the upper command device 8 or the like in step S6-2, the power conversion device updates the active power command value Pref to the new active power value Pref' in step S6-6. As a result of the update, the output of the power conversion device changes (step S6-7).

[0049] If a new active power value Pref' has not been received in step S6-2, the process proceeds to step S6-3, where an operation determination unit (not shown) included in the power conversion device determines whether the power conversion device is operating in an isolated operation state. For example, the power conversion device may determine whether the power conversion device is operating in an isolated operation state by an isolated operation detection method included in the power conversion device, by receiving a contact signal or the like of the interconnection point relay 51, or by manual input or operation by the user of the power conversion device.

[0050] If the power converter is not operating autonomously, i.e., if the power converter is operating in grid-connected mode, the process proceeds to step S6-7. If the power converter is operating autonomously, the process proceeds to S6-4, where the active power command value setting unit 33 determines whether the power converter is charging, i.e., whether the active power Pout that the power converter is actually charging or discharging is positive. If the power converter is not charging, the process proceeds to step S6-7, and if the power converter is charging, the process proceeds to step S6-5.

[0051] Then, the active power command value setting unit 33 executes a change process to autonomously update the active power command value Pref by subtracting the active power Pout from the active power command value Pref. That is, Pref after the update process becomes Pref-Pout before the update process. Then, the output of the power conversion device changes in accordance with the change process (step S6-7).

[0052] 5, at the operating point 1, both the power electronics devices 101 and 102 transition to step S6-3 and then transition to step S6-4. Since the power electronics device 101 is discharging, it transitions to step S6-7, but since the power electronics device 102 is charging, it transitions to step S6-5.

[0053] Then, the active power command value Pref2 is autonomously updated in the active power command value setting unit 33. During grid-connected operation, Pref2=Pref2', but in step S6-5, the active power command value setting unit 33 sets the active power command value Pref2 to Pref2'-Pout2_1.

[0054] The set active power command value Pref2 is sent to the phase command generation unit 32. The phase command generation unit 32 sends θref (phase command) to the main circuit control unit 36 to control the active power output by the main circuit. As a result, the droop characteristic of the power conversion device 102 moves from line b to line c in FIG. 5, and the operating point of the power conversion device 102 transitions to point 2 in FIG. 5.

[0055] However, since the active power output of the power conversion device 102 becomes 0 [kW] from Pout2_1, Pout1 + Pout2 = Pout1_1 < -Pload. This is a state where the supply power from the power conversion device is large relative to the load consumption power, so the operating point moves to a point where Pout1 + Pout2 = -Pload and the angular frequency change amount command Δωref’ becomes a common value. The operating point of the power conversion device 101 transitions from point 1 to point 3 in FIG. 5 (step S6-7), and the operating point of the power conversion device 102 transitions from point 2 to point 3 in FIG. 5 (step S6-7).

[0056] Let the actual active powers of the power conversion device 101 and the power conversion device 102 at this point 3 be represented as Pout1_3 and Pout2_3. At point 3, Pout1_3 < 0 < Pout2_3 and Pout1_3 + Pout2_3 = -Pload. The power conversion device 101 is in a discharging operation, and the power conversion device 102 is in a charging operation to supply power to the AC load 6. In this state, power can be supplied to the AC load 6, but power transfer occurs between the power conversion devices, and it is in the same state as point 1.

[0057] Then, similar to the case of point 1, in steps S6-4 and S6-5, the power conversion device 102 detects that it is charging based on the value of Pout received by the active power command value setting unit 33 from the power calculation unit 31, and the active power command value setting unit 33 autonomously updates the active power command value Pref2.

[0058] At this time, Pref2=Pref2'-Pout2_1-Pout2_3. In this manner, similar to the transition from point 1 to point 2, the operating point of the power electronics device 102 further transitions from point 3. The transition destination is point 4. The droop characteristic of the power electronics device 102 at this time is indicated by line d in FIG.

[0059] Here, power conversion device 102 operates at point 4 and the active power output becomes 0 [kW], so Pout1+Pout2=Pout1_3<-Pload. This is a state in which the power supplied from the power conversion device is large compared to the load power consumption, so the operating point of power conversion device 101 moves from point 3 in Fig. 5, and the operating point of power conversion device 102 moves from point 4 in Fig. 5 in accordance with the droop characteristics so that Pout1+Pout2=-Pload is established.

[0060] By repeating the above operation, the operating points of the power conversion devices 101 and 102 move to point 5. The droop characteristic of the power conversion device 102 at this time is line e in FIG. 5. If the actual active powers of the power conversion devices 101 and 102 at point 5 are represented as Pout1_5 and Pout2_5, respectively, then Pout1_5 <Pout2_5=0[kW]である。また、Pout1+Pout2=Pout1_5=-Ploadである。

[0061] Since the sum of the discharge power of power conversion device 101 and power conversion device 102 is equal to the load power consumption, the operating points of power conversion device 101 and power conversion device 102 each remain at point 5 and do not move according to the droop characteristic as described above.

[0062] At operating point 5, power conversion device 101 discharges and power conversion device 102 operates at 0 kW, so that power can be supplied to AC load 6 without power exchange between power conversion devices 101 and 102.

[0063] As described above, the control of this embodiment is processed within the active power command value setting unit 33 of the power conversion device, and does not require the upper command device 8 of the power conversion device. Therefore, when the power conversion devices 101 and 102 transition to independent operation due to an accident, power outage, or the like occurring in the AC system 5, the control of this embodiment is executed even if communication with the upper command device 8 of the power conversion devices is interrupted.

[0064] 7 is a graph showing the time change of the active power and the time change of the angular frequency change amount command of the power conversion device in the first embodiment of the present invention. The horizontal axis represents time, and the origin is the time when the power conversion device 101 and the power conversion device 102 transition to independent operation.

[0065] In the waveform of the active power, the power conversion device 101 has a line f, and the power conversion device 102 has a line g. As described above, the angular frequency change amount command Δωref′ (line h) has a common value for the power conversion device 101 and the power conversion device 102.

[0066] The control in this embodiment is executed for each calculation cycle of the control units of the power conversion device 101 and the power conversion device 102. This calculation cycle is often equal to or shorter than several hundred microseconds, and at this time, the active power Pout2_3 of the operating point 3 of the power conversion device 102 becomes very small.

[0067] Therefore, the locus of the operating point of the power conversion device 102 is not actually a sawtooth locus like point 1 ---> point 2 ---> point 3 ---> point 4 ---> ... in Fig. 6, but a smooth locus from point 1 to point 5, and when the active power Pout2 of the power conversion device 102 becomes 0 [kW] at point 2, the frequency increases at Pout2 ≒ 0 [kW]. The locus of the operating point of the power conversion device 101 moves from point 1 to point 4, and therefore becomes an overshooting locus.

[0068] FIG. 8 is a graph showing an example of the relationship among the active power command value, the active power, and the angular frequency change amount command when the load power consumption in the system configuration example of Embodiment 1 of the present invention fluctuates. The droop characteristics of the power conversion device 101 are line i, and the droop characteristics of the power conversion device 102 are lines j and k. At the operating point 5, the droop characteristics of the power conversion device 101 are line i, and the droop characteristics of the power conversion device 102 are line j.

[0069] After the operating points of the power conversion device 101 and the power conversion device 102 shift to point 5 as described above, when the power consumption of the AC load increases and becomes Pload2 (Pload2 > Pload), the power conversion device 101 and the power conversion device 102 increase the discharge power to cover the load power consumption.

[0070] At this time, the operating points of the power conversion device 101 and the power conversion device 102 move from point 5 according to the droop characteristics and shift to point 6 where Pout1 + Pout2 = -Pload2 and the angular frequency change amount command Δωref' becomes a common value. At this time, since both the power conversion device 101 and the power conversion device 102 are discharging, the control for autonomously updating the above-mentioned active power command value is not implemented.

[0071] On the other hand, after the operating points of the power conversion device 101 and the power conversion device 102 shift to point 5 as described above, when the power consumption of the AC load decreases and becomes Pload3 (0 < Pload3 < Pload), the power conversion device 101 and the power conversion device 102 decrease the discharge power and discharge the same amount of power as the load power consumption.

[0072] At this time, the operating points of the power conversion device 101 and the power conversion device 102 move from point 5 according to the droop characteristics and shift to point 7 where Pout1 + Pout2 = -Pload3 and the angular frequency change amount command Δωref' becomes a common value. If the actual active powers of the power conversion device 101 and the power conversion device 102 at this point 7 are represented as Pout1_7 and Pout2_7, then at point 7, Pout1_7 < 0 < Pout2_7.

[0073] That is, the power conversion device 101 performs a discharging operation, and the power conversion device 102 performs a charging operation to supply power to the AC load 6, and power is being supplied to the AC load 6, but power is being exchanged between the power conversion devices. Therefore, in the power conversion device 102, which is the power conversion device that is charging as described above, an update process is executed in step S6-5 to autonomously update the active power command value in the same manner as described above.

[0074] As a result, they shift to operating point 8 where Pout1=-Pload3, Pout2=0 [kW], and the angular frequency change amount command Δωref′ is a common value. The droop characteristic of the power conversion device 102 at this time is line k in FIG.

[0075] The above-described example of control in this embodiment is performed immediately after transition to independent operation due to, for example, an accident, a power outage, or the like occurring in the AC system 5. When a certain amount of time has elapsed after transition to independent operation, the upper command device 8 of the power conversion devices can generate an optimal active power value Pref' for each power conversion device during independent operation and transmit it to each power conversion device.

[0076] When the active power command value setting unit 33 of each power conversion device receives a new active power value Pref'' from the upper command device 8 of the power conversion device, it resets the autonomous updating of the active power command value Pref that had been performed up to that point, sets Pref=Pref'', and can perform operation in accordance with the upper command device 8 of the power conversion device.

[0077] In this embodiment, the case where there are two power conversion devices has been described, but the number of power conversion devices is not limited to two. When three or more power conversion devices are connected, the above-mentioned control may be performed on the third and subsequent power conversion devices. When there is one power conversion device, the power conversion device discharges so that power can be supplied to the load, and therefore the power conversion device does not perform charging during independent operation. Therefore, this control is not performed, but having this control program does not affect other operations. EXAMPLES

[0078] In this embodiment, the description of the same points as in the first embodiment will be omitted as appropriate.

[0079] Fig. 9 shows a configuration example of a power conversion device according to a second embodiment of the present invention. In this embodiment, an active power command value setting unit 33 receives an update determination frequency fcheck or an update determination angular frequency ωcheck together with an active power value Pref' from a host command device 8 of the power conversion device (e.g., an energy management system, not shown in Fig. 9) located outside the power conversion device 1 via wired communication or wireless communication.

[0080] When the update determination frequency fcheck is received, the active power command value setting unit 33 can obtain the update determination angular frequency ωcheck=2π×fcheck by calculation.

[0081] 10 is a block diagram showing an example of a system configuration according to a second embodiment of the present invention. In this embodiment, an AC generator 9 (for example, a private power generating facility such as a diesel generator) is connected to AC ends of a power conversion device 101 and a power conversion device 102 via a private line 52 in addition to an AC system 5 and an AC load 6.

[0082] In this embodiment, the AC load 6 is a load that consumes power Pload (Pload>0) and does not generate regeneration. The configurations of the power conversion device 101 and the power conversion device 102 are the same as that of the power conversion device 1. Also, it is assumed that the power conversion device 101 and the power conversion device 102 use the same values ​​for the gains Kp and Kq.

[0083] The AC generator 9 is connected to the power conversion device 101, the power conversion device 102, and the AC load 6 side of the interconnection point relay 51 of the AC system 5, and is electrically connected to the power conversion device 101, the power conversion device 102, and the AC load 6 even when the AC system 5 is disconnected by the interconnection point relay 51.

[0084] In this embodiment, the AC generator 9 is directly connected to the power converter 101, the power converter 102, and the AC load 6, but may be connected via a transformer or the like.

[0085] It is assumed that the upper command device 8 of the power conversion devices communicates with the power conversion devices 101 and 102, and transmits Pref1' (Pref1'>0) as the active power value Pref' to the power conversion device 101, and transmits Pref2' (Pref2'>Pref1') as the active power value Pref' to the power conversion device 102. Then, the active power command value setting units 33 of the power conversion devices 101 and 102 respectively generate active power command values ​​Pref1 and Pref2.

[0086] In the first embodiment, the active power command values ​​Pref1 and Pref2 are changed according to Fig. 6. On the other hand, in the present embodiment in which the AC generator 9 is connected, the active power command values ​​Pref1 and Pref2 are changed using the angular frequency command value ωref (the sum of the reference angular frequency and the angular frequency change amount command Δωref') of the power conversion device and the update judgment angular frequency ωcheck in addition to these operating conditions. The reference angular frequency is 2π×50 rad / s, as in the first embodiment.

[0087] FIG. 11 is a graph showing an example of the relationship between the active power command value, the angular frequency command, and the update determination angular frequency in the example of the system configuration according to the second embodiment of the present invention.

[0088] The initial values ​​of the active power command values ​​Pref1 and Pref2 are Pref1' and Pref2', respectively. At this time, the droop characteristics of the power conversion device 101 are as shown by line l, and the droop characteristics of the power conversion device 102 are as shown by line m.

[0089] Here, among the angular frequency command values ​​when Pout=0 for each power conversion device, that is, the angular frequency command values ​​corresponding to the intercepts of the vertical axis (angular frequency command axis) in the droop characteristics of each power conversion device, the angular frequency command value closest to the reference angular frequency which is the origin of the graph becomes the angular frequency ωcheck for update judgment.

[0090] 11, since Pref2'>Pref1', the intercept of the vertical axis (angular frequency command axis) of each droop characteristic that is closest to the reference angular frequency is the intercept of the power conversion device 101. Therefore, the update determination angular frequency ωcheck in this embodiment is the angular frequency command value when Pout=0 for the power conversion device 101.

[0091] In this embodiment, the upper command device 8 of the power conversion device determines the update judgment angular frequency ωcheck during grid-connected operation and transmits it to each of the power conversion devices 101 and 102. In this embodiment, the power conversion devices 101 and 102 do not communicate with each other, so they cannot know each other's active power command value Pref. In addition, although not described in the present invention, the droop characteristics (the slopes in FIG. 11) of each device may also be different, and the update judgment angular frequency ωcheck cannot be calculated independently. Therefore, the update judgment angular frequency ωcheck is obtained from the upper command device 8. However, if the power conversion devices in the system are configured to be able to exchange information with each other, they can share information about Pref and the droop characteristics to autonomously calculate the update judgment angular frequency ωcheck and operate according to this.

[0092] Since the upper command device 8 of the power conversion devices transmits active power values ​​Pref1', Pref2' to the power conversion devices 101 and 102, respectively, if the gains Kp of the power conversion devices 101 and 102 are known, it is possible to determine the update determination angular frequency ωcheck and transmit this to the power conversion devices 101 and 102. The active power command value setting units 33 of the power conversion devices 101 and 102 generate active power command values ​​Pref1, Pref2 using the received update determination angular frequency ωcheck.

[0093] FIG. 12 is a flowchart of a method for updating an active power command value of a power conversion device according to the second embodiment of the present invention.

[0094] Steps S12-1, S12-2, S12-3, S12-11, and S12-12 in Fig. 12 are similar to steps S6-1, S6-2, S6-3, S6-6, and S6-7 in Fig. 6 of the embodiment 1. In the following, steps S12-4 to S12-10 will be mainly described.

[0095] FIG. 13 is a graph showing Example 1 of the relationship between the active power command value, the active power, and the angular frequency change amount command in the system configuration example of the second embodiment of the present invention.

[0096] In this example, an AC generator and two power conversion devices that charge the generator were operating at point 0, but moved to point 1 due to a transition to independent operation, with power conversion device 101 discharging and power conversion device 102 charging.

[0097] Note that the power storage device 7 to which the power conversion device is connected is assumed to be chargeable, and if the power storage device 7 subsequently becomes fully charged, the power conversion device may be controlled not to charge the power storage device 7. That is, in Fig. 12, if the power storage device 7 is fully charged, a determination is made before S12-2 as to whether the power storage device 7 is fully charged, and if the power storage device 7 is fully charged, the process proceeds to S12-6, and if the power storage device 7 is not fully charged, the process continues from S12-2 onwards. By configuring in this manner, it is possible to prevent a fully charged power conversion device from charging, and to discharge the power storage device when necessary.

[0098] The AC generator 9 outputs a constant power, and in FIG. 13, the characteristics of the AC generator 9 are shown by line n.

[0099] It is assumed that power conversion device 101 and power conversion device 102 have received a charging command (Pref1', Pref2'>0) from upper command device 8 of the power conversion devices during grid-connected operation, and the flow after transitioning to independent operation (S12-3: Yes) will be described.

[0100] As shown in Fig. 13, when Pref1', Pref2'>0, the value of the update determination angular frequency ωcheck is less than the reference angular frequency 2π × 50. Therefore, when the process proceeds to step S12-4 in Fig. 12, the process branches to No.

[0101] As in the description of the first embodiment, it is assumed that the operating points of the power conversion devices 101 and 102 have shifted to point 1 in FIG. 13 due to the shift to isolated operation.

[0102] Since the angular frequency command value ωref at point 1 is smaller than the angular frequency ωcheck for update judgment, the result of step S12-5 is determined as No, and the process proceeds to step S12-6. At this time, in FIG. 13, since only the power conversion device 102 is charging, in step S12-7, the active power command value setting unit 33 of the power conversion device 102 executes a change process to change the active power command value Pref, and the changed active power command value Pref is sent to the phase command generating unit 32. This change process is performed by dividing the Pout at the time of update from the Pref before update to calculate a new Pref, as in the first embodiment. The phase command generating unit 32 sends θref (phase command) to the main circuit control unit 36 ​​to control the active power output by the main circuit. As a result, the droop characteristic of the power conversion device 102 moves from the line p to the line q in FIG. 13, and the operating point of the power conversion device 102 transitions to point 2 in FIG. 13.

[0103] On the other hand, since the power conversion device 101 is discharging, the process transitions from step S12-6 to step S12-12.

[0104] When the active power output of the power conversion device 102 becomes 0 [kW] and the sum of the discharge powers of the AC generator 9, the power conversion device 101, and the power conversion device 102 becomes large relative to the load power consumption, the sum of these discharge powers moves to a point where it is equal to the load power consumption and the angular frequency command ωref has a common value. As a result, the operating point of the power conversion device 101 transitions from point 1 to point 3 in Fig. 13, and the operating point of the power conversion device 102 transitions from point 2 to point 3 in Fig. 13.

[0105] At point 3, the angular frequency command value ωref is lower than the update judgment angular frequency ωcheck. Therefore, the No branch is taken again in step S12-5 in FIG.

[0106] Subsequently, since the power conversion device 101 is discharging and the power conversion device 102 is charging at the operating point 3, the process of changing the active power command value Pref of the power conversion device 102 is executed in step S12-7 in Fig. 12. Since the power conversion device 101 is discharging, the process of changing the active power command value Pref1 is not executed.

[0107] Thereafter, as in the description of the first embodiment, the operating point of the power converter 102 shifts to point 4, and then to point 5. At this time, the droop characteristic of the power converter 102 shifts to line s via line r in FIG.

[0108] At the operating point 5, the power conversion device 101 discharges and the power conversion device 102 operates at 0 [kW], so that power can be supplied to the AC load 6 without power exchange between the power conversion devices 101 and 102.

[0109] Next, a case will be described where the power consumption of the AC load 6 changes after the operating point has shifted to point 5. If the power consumption of the AC load 6 increases, the sum of the discharge powers of the AC generator 9, the power conversion device 101, and the power conversion device 102 becomes smaller than the load power consumption. At this time, the operating point moves to a point where the sum of these discharge powers is equal to the load power consumption and the angular frequency command ωref has a common value.

[0110] This operating point is represented as point 6 in Fig. 13. Here, the angular frequency command value ωref at operating point 6 is lower than that at operating point 5, and step S12-5 in Fig. 12 takes the answer No. Then, since both power conversion device 101 and power conversion device 102 are discharging, the process of changing the active power command value in step S12-7 in Fig. 12 is not performed, and the operating point is stabilized at point 6.

[0111] Next, a case where the power consumption of the AC load 6 decreases will be described. The sum of the discharge powers of the AC generator 9, the power converter 101, and the power converter 102 moves to a point where it is equal to the load power consumption and the angular frequency command ωref has a common value.

[0112] This operating point is represented as point 7 in Fig. 13. Operating point 7 is the case where the AC load 6 becomes lightly loaded and the constant power output of the AC generator 9 becomes oversupplied.

[0113] At this time, the power conversion device 101 and the power conversion device 102 may perform charging operations. Since the angular frequency command value ωref at the operating point 7 is higher than the update determination angular frequency ωcheck, the Yes branch is taken in step S12-5 in FIG.

[0114] The operations of the power conversion devices 101 and 102 when the power consumption of the AC load 6 changes after the operating point shift in the second embodiment can be similarly implemented in the first embodiment as long as the upper command device 8 of the power conversion devices transmits the update determination angular frequency ωcheck to each of the power conversion devices 101 and 102.

[0115] Although the AC load 6 has been described as a load that does not generate regeneration, it may be a regenerative load, in which case the power conversion device will follow the operation when the power consumption of the AC load 6 has decreased as described above. In a configuration similar to that of the first embodiment that does not include the AC generator 9, the operation of the power conversion device can be appropriately controlled by following this embodiment while the AC load 6 is in regeneration.

[0116] Next, FIG. 14 is a graph showing the relationship between the active power command value, the active power, and the angular frequency change amount command in the system configuration example of the second embodiment of the present invention.

[0117] This is an example of a case where it is not necessary to change the active power command value of the power conversion device. The AC generator 9 and the two power conversion devices that were charging were operating in grid-connected mode, but even after switching to independent operation, the two power conversion devices continue charging at point 1.

[0118] When shifting to autonomous operation, the angular frequency command values ωref of the power conversion devices 101 and 102 are closer to the reference angular frequency 2π×50 than the update determination angular frequency ωcheck. For this reason, at the branch in step S12-5 of FIG. 12, Yes is taken and the process does not proceed to step S12-7, so the active power command values Pref1 and Pref2 are not changed.

Embodiment

[0119] In this embodiment, descriptions of the same parts as in Embodiment 1 are omitted as appropriate. The configuration example of the power conversion device and the system configuration example in this embodiment are the same as those in FIGS. 9 and 10.

[0120] FIG. 15 is a graph showing the relationship between the active power command value, the angular frequency command, and the update determination angular frequency in Embodiment 3 of the present invention. The droop characteristic of the power conversion device 101 is line t, and the droop characteristic of the power conversion device 102 is line u.

[0121] In Embodiment 2, the upper command device 8 of the power conversion device transmitted the active power values for charging to the power conversion device 101 and the power conversion device 102, but in this embodiment, the active power values for discharging are transmitted. That is, it is assumed that the upper command device 8 of the power conversion device transmits Pref1’ (Pref1’ < 0) as the active power value Pref’ to the power conversion device 101 and Pref2’ (Pref1’ < Pref2’ < 0) as the active power value Pref’ to the power conversion device 102.

[0122] Here, similar to Embodiment 2, among the angular frequency command values when each power conversion device has Pout = 0, that is, the angular frequency command values corresponding to the intercepts of the vertical axis (angular frequency command axis) of the droop characteristics of each power conversion device, the angular frequency command value closest to the reference angular frequency is set as the update determination angular frequency ωcheck.

[0123] In Fig. 15, since 0 > Pref2’ > Pref1’, among the vertical axis (angular frequency command axis) intercepts of the loop characteristics, the one closest to the reference angular frequency is the intercept of the loop characteristic of the power conversion device 102. Therefore, the angular frequency ωcheck for update determination in this embodiment is the angular frequency command value when the power conversion device 102 has Pout = 0.

[0124] Fig. 16 is a graph showing the relationship between the active power command value, active power, and angular frequency change amount command in Embodiment 3 of the present invention.

[0125] In this embodiment, during the interconnected operation, power was supplied to the AC load by the power of the AC generator 9 at the operating point of point 0 and the discharges of the two power conversion devices. However, this is an example of a system where when the independent operation is entered, at point 1, the power conversion device 101 discharges and the power conversion device 102 charges. The AC generator 9 outputs a constant power.

[0126] In Fig. 16, the characteristic of the AC generator 9 is line v. Also, it is assumed that the power conversion device 101 and the power conversion device 102 have received a discharge command (Pref1’ < Pref2’ < 0) from the upper command device 8 of the power conversion device as described above.

[0127] In this embodiment, the method for updating the active power command value of the power conversion device is the same as in Embodiment 2 and follows Fig. 12. In this embodiment, as shown in Figs. 15 and 16, since the angular frequency ωcheck for update determination > the reference angular frequency 2π × 50, when proceeding to S12-4 in Fig. 12, it branches to Yes.

[0128] Similar to Embodiment 2, the transition of the operating point will be described using Figs. 12 and 16. It is assumed that due to the transition to independent operation, the operating points of the power conversion device 101 and the power conversion device 102 have shifted to point 1 in Fig. 16. Since the angular frequency command value ωref at the operating point 1 is higher than the angular frequency ωcheck for update determination, it branches to No in step S12-8.

[0129] Then, since the power conversion device 101 is discharging (step S12-9: Yes), in step S12-10, the active power command value setting unit 33 of the power conversion device 101 executes a change process to increase the active power command value Pref, and the changed active power command value Pref is sent to the phase command generating unit 32. This change process is performed by dividing the updated Pout (<0) from the pre-update Pref to calculate a new Pref, as in the first embodiment. The phase command generating unit 32 sends θref (phase command) to the main circuit control unit 36 ​​to increase the active power output by the main circuit. As a result, the droop characteristic of the power conversion device 101 moves from the line w to the line x in FIG. 16, and the operating point transitions to point 2 in FIG. 16.

[0130] Since the active power output of the power conversion device 101 becomes 0 [kW], the sum of the discharge powers of the AC generator 9, the power conversion devices 101, and the power conversion devices 102 decreases and becomes small relative to the load power consumption. Then, the operating point moves to a point where the sum of these discharge powers is equal to the load power consumption and the angular frequency command ωref becomes a common value. The operating point of the power conversion device 101 transitions from point 2 to point 3 in Fig. 16, and the operating point of the power conversion device 102 transitions from point 1 to point 3 in Fig. 16.

[0131] At the operating point 3, the angular frequency command value ωref is higher than the update judgment angular frequency ωcheck. Therefore, in step S12-8 in FIG.

[0132] Next, since the power conversion device 101 is performing a discharging operation and the power conversion device 102 is performing a charging operation at the operating point 3, in step S12-10 of Fig. 12, the active power command value setting unit 33 of the power conversion device 101 changes the active power command value Pref, and the changed active power command value Pref is sent to the phase command generating unit 32. The phase command generating unit 32 sends θref (phase command) to the main circuit control unit 36, and changes the active power output by the main circuit. The active power command value setting unit 33 further updates the active power command value Pref1.

[0133] Thereafter, the transition of the operating point as described above is repeated according to Fig. 12. Eventually, the operating points of power conversion device 101 and power conversion device 102 move to point 4. At this time, the droop characteristic of power conversion device 101 is line y in Fig. 16. The droop characteristic of power conversion device 102 does not move and is line z in Fig. 16.

[0134] At operating point 4, the angular frequency command value ωref = the update determination angular frequency ωcheck, so the Yes branch is taken in step S12-8 in Fig. 12. Therefore, at this time, the processes in and after step S12-10 are not performed, and the operating point stabilizes at point 4. At operating point 4, power conversion device 101 is discharging, and power conversion device 102 is 0 kW, preventing a mixture of charging and discharging power conversion devices.

[0135] FIG. 17 is a graph showing the relationship between the active power command value, the active power, and the angular frequency change amount command in the third embodiment of the present invention.

[0136] The position of the operating point 1 is different compared to the example of the relationship between the active power command value, active power, and angular frequency change command shown in Fig. 16. That is, the power consumption of the AC load 6 is different and it is assumed to be a light load.

[0137] The transition of the operating point will be described with reference to Fig. 12 and Fig. 17. It is assumed that the operating points of the power conversion devices 101 and 102 have shifted to point 1 in Fig. 17 due to the transition to independent operation. Since the angular frequency command value ωref of the operating point 1 is higher than the update determination angular frequency ωcheck, the process branches to No in step S12-8.

[0138] Then, in step S12-10, the discharging power conversion device 101 increases the active power command value Pref1, which causes the droop characteristic of the power conversion device 101 to move from line a2 to line b2 in Fig. 16, and the operating point transitions to point 2 in Fig. 17.

[0139] Thereafter, the transition of the operating point as described above is repeated according to Fig. 12. Eventually, the operating points of power conversion devices 101 and 102 move to point 3 in Fig. 17. At this time, the droop characteristic of power conversion device 101 is line c2 in Fig. 16. The droop characteristic of power conversion device 102 does not move and is line d2 in Fig. 16.

[0140] At the operating point 3, the angular frequency command value ωref>the update determination angular frequency ωcheck, so the No branch is taken at step S12-8 in Fig. 12. However, at the operating point 3, the power conversion device 101 is 0 kW, the power conversion device 102 is in a charging operation, and there is no power conversion device that discharges, so the process at step S12-10 is not performed. EXAMPLES

[0141] Fig. 18 shows a system configuration example in the fourth embodiment of the present invention. In this configuration example, compared to the system configuration examples (Fig. 10) shown in the second and third embodiments, only one power electronics device (power electronics device 101) is used.

[0142] In this configuration example, the power conversion device 101 receives the update determination angular frequency ωcheck, similarly to the second and third embodiments. Then, the active power command value Pref1 is updated as necessary, similarly to the second and third embodiments.

[0143] In this configuration example, since an AC generator 9 is connected in addition to the power conversion device 101, depending on the output of the AC generator 9 and the power consumption of the AC load 6, the power supply and demand of the entire system can be balanced by charging the power conversion device 101.

[0144] Therefore, if the active power command value Pref1 is constantly updated so that the power conversion device 101 does not charge during independent operation without using the update determination angular frequency ωcheck as shown in the first embodiment, the power supply will be excessive. Therefore, the active power command value Pref1 is updated using the update determination angular frequency ωcheck as in the second and third embodiments.

[0145] In this embodiment, the update determination angular frequency ωcheck is an angular frequency command value when the power conversion device 101 is at Pout=0, that is, an angular frequency command value corresponding to an intercept of the vertical axis (angular frequency command axis) in the droop characteristics of the power conversion device 101. In this embodiment as well, by following the flow of FIG. 12, it becomes possible to appropriately control the operation of the power conversion device. [Explanation of symbols]

[0146] 1, 101, 102...power conversion device, 2...main circuit, 3...control unit, 4...AC filter, 5...AC system, 6...AC load, 7...power storage device, 8...high-level command device for power conversion device, 9...AC generator, 31...power calculation unit, 32...phase command generation unit, 33...active power command value setting unit, 34...reactive power command generation unit, 35...reactive power control (AQR) unit, 36...main circuit control unit

Claims

1. A power conversion device connected to a power storage device, an operation determination unit that determines whether the power conversion device is in an isolated operation state or an interconnected operation state; a power calculation unit that calculates the power input and output to and from the power storage device; an active power command value setting unit that determines an active power command value based on the received active power value and the active power calculated by the power calculation unit; a main circuit that converts power based on an active power command value; The active power command value setting unit is a power conversion device capable of executing a change process for changing the active power command value to a value corresponding to the input / output of power of the power storage device in an independent operation state.

2. The power conversion device according to claim 1 , wherein the change process is performed when the power storage device is storing power.

3. The active power command value setting unit receives an update judgment angular frequency from an external device, The change process is 2. The power conversion device according to claim 1, wherein the update determination angular frequency is equal to or lower than a predetermined reference angular frequency, the angular frequency command of the power conversion device is less than the update determination angular frequency, and the power storage device is storing power.

4. The active power command value setting unit receives an update judgment angular frequency from an external device, The change process is 2. The power conversion device according to claim 1, wherein the update determination angular frequency is greater than a predefined reference angular frequency, the angular frequency command of the power conversion device is greater than the update determination angular frequency, and the power storage device is outputting power.

5. 4. The power conversion device according to claim 1, wherein the change process is a process of changing the active power command value to a value that does not input power to the power storage device.

6. 5. The power conversion device according to claim 1, wherein the change process is a process of changing the active power command value to a value that causes the power storage device not to output power.

7. 5. The power conversion device according to claim 1, wherein the change processing is processing for calculating an active power command value after the change processing by subtracting an active power at the time of the change processing from an active power command value before the change processing.

8. A method for controlling a power conversion device connected to a power storage device, comprising: Determine whether the power conversion device is in an isolated operation state or a grid-connected operation state; Calculating the power input and output by the power storage device; determining an active power command value from the received active power value and the active power calculated by the power calculation unit; A control method for a power conversion device capable of executing a change process for changing an active power command value to a value corresponding to the input / output of power of a power storage device in an independent operation state.

9. The method for controlling a power conversion device according to claim 8 , wherein the change process is executed when the power storage device is storing power.

10. The angular frequency for update judgment is received from an external device. The change process is 9. The control method for a power conversion device according to claim 8, which is executed when an angular frequency for update determination is equal to or lower than a predefined reference angular frequency, an angular frequency command for the power conversion device is less than the angular frequency for update determination, and a power storage device is storing power.

11. The angular frequency for update judgment is received from an external device. The change process is 9. The control method for a power conversion device according to claim 8, which is executed when an angular frequency for update determination is greater than a predefined reference angular frequency, an angular frequency command for the power conversion device is greater than the angular frequency for update determination, and a power storage device is outputting power.

12. 11. The method for controlling a power conversion device according to claim 8, wherein the change process is a process for changing the active power command value to a value that does not input power to the power storage device.

13. 12. The method for controlling a power conversion device according to claim 8, wherein the change process is a process of changing the active power command value to a value that causes the power storage device to not output power.

14. 12. The method for controlling a power conversion device according to claim 8, wherein the change processing is processing for calculating an active power command value after the change processing by subtracting an active power at the time of the change processing from an active power command value before the change processing.

Images