Power control device, power control system

Abstract

To provide a power control device and a power control system capable of suppressing an erroneous output of a notification instruction while the power control device is operated in a self-consumption mode.SOLUTION: In a control device for a power control device (a power conditioner) of a grid provided with a distributed type power source (a photovoltaic power generation panel) and links to a power system, a second control block 51B comprises: a first power control unit 63 for controlling an output of an inverter circuit for converting a power supplied from the distributed type power source from DC to AC and outputting it; a notification circuit 70 for outputting a notification instruction when an output target value outputted from a first selection circuit 61 matches an output limit value inputted to the first selection circuit 61: and a suppression circuit 80 for suppressing an output of the notification instruction while a self-consumption mode is selected by adding a prescribed value to the output limit value instructed from an electric enterprise company when the self-consumption mode is selected.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a technique for notifying a user that the output [W] of an inverter circuit is limited to an output limit value instructed by an electric utility company. [Background technology]

[0002] From the viewpoint of reducing dependency on fossil fuels and environmental issues, the introduction of distributed power sources, such as photovoltaic (PV) power generation, is being promoted. Electricity generated by solar panels is converted from direct current to alternating current using an inverter circuit and supplied to loads. A grid that has distributed power sources is connected to the power system, and surplus electricity from distributed power sources can be sent to the power system and sold.

[0003] In recent years, due to concerns that the large-scale introduction of distributed power sources may result in an oversupply of electricity in the power grid, inverter circuit output may be limited at the request of the electric utility. The electric utility provides an output limiting schedule that sets the upper limit of inverter circuit output on an hourly basis via an operation server. Users of distributed power sources limit the output of the inverter circuits according to the output limiting schedule.

[0004] Patent Document 1 listed below discloses a power storage type photovoltaic power generation system including a solar cell, a storage battery, a backflow prevention diode, a power conditioner, a load, and the like.

[0005] The following Patent Document 2 discloses an output control device that can control a plurality of PCSs in a manner that does not restrict the outputs from the PCSs more than necessary. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4765162 [Patent Document 2] JP 2018-153003 A Summary of the Invention [Problem to be solved by the invention]

[0007] When limiting the output of the inverter circuit at the request of the electric utility, it is possible to output a notification to inform users, in order to avoid users having doubts about the fact that the output of the distributed power source is lower than the expected output.

[0008] One of the functions of the power control device is a self-consumption mode, in which the power generated by the distributed power source is consumed only by the load in the grid and is not transmitted to the power system.

[0009] When the inverter circuit's output target value in self-consumption mode matches the output limit value provided by the electric utility, it may not be possible to determine which of the two values ​​has been selected as the inverter circuit's output target value. As a result, when the inverter circuit is operating in "self-consumption mode," the power control device may erroneously output a "notification command notifying that output is being limited at the request of the electric utility."

[0010] The present technology discloses a technology for suppressing a power control device from erroneously outputting a notification command when an inverter circuit is operating in a self-consumption mode. [Means for solving the problem]

[0011] A power control device for a grid that is equipped with distributed power sources and is connected to a power system includes an inverter circuit that converts power supplied from the distributed power sources from direct current to alternating current and outputs the power, and a control device that controls the output of the inverter circuit. The control device includes a first selection circuit that selects the smallest value of three input values: a rated output of the inverter circuit, an output target value in a self-consumption mode, and an output limit value that is equal to or greater than the output target value in the self-consumption mode and is instructed by an electric utility, and outputs the smallest value as the output target value of the inverter circuit; a first power control unit that controls the output of the inverter circuit in accordance with the output target value output from the first selection circuit; a notification circuit that outputs a notification command when the output target value output from the first selection circuit matches the output limit value input to the first selection circuit; and a suppression circuit that suppresses the output of the notification command while the self-consumption mode is selected by adding a predetermined value to the output limit value instructed by the electric utility when the self-consumption mode is selected.

[0012] The present technology can be applied to a power control system and a power control method. Effect of the Invention

[0013] It is possible to prevent erroneous output of a notification command during operation in the self-consumption mode. [Brief description of the drawings]

[0014] [Figure 1] Microgrid Block Diagram [Diagram 2] Microgrid Block Diagram [Diagram 3] Solar cell output characteristics [Figure 4] Output limiting schedule for bidirectional inverter circuits [Diagram 5] Function setting screen [Figure 6] First control block [Figure 7] Second Control Block [Figure 8] An enlarged view of a part of Figure 7 [Figure 9]Block diagram of a microgrid

Embodiment for Carrying Out the Invention

[0015] A power control device for a grid that includes a distributed power source and is connected to a power system includes an inverter circuit that converts the power supplied from the distributed power source from direct current to alternating current and outputs it, and a control device that controls the output of the inverter circuit. The control device selects the minimum value among three input values, namely, the rated output of the inverter circuit, the output target value in the self-consumption mode, and the output limit value instructed by the electric utility and that is greater than or equal to the output target value in the self-consumption mode, and outputs it as the output target value of the inverter circuit. A first selection circuit; a first power control unit that controls the output of the inverter circuit according to the output target value output from the first selection circuit; and a notification circuit that outputs a notification command when the output target value output from the first selection circuit matches the output limit value input to the first selection circuit. When the self-consumption mode is selected, a suppression circuit that suppresses the output of the notification command during the selection of the self-consumption mode by adding a predetermined value to the output limit value instructed by the electric utility.

[0016] The first selection circuit selects and outputs the minimum value among the three input values, namely, the rated value of the inverter circuit, the output target value in the self-consumption mode, and the output limit value instructed by the electric utility. Since the output limit value instructed by the electric utility is greater than or equal to the output target value in the self-consumption mode, when the self-consumption mode is selected, among the rated value of the inverter circuit, the output target value in the self-consumption mode, and the output limit value instructed by the electric utility, the output target value in the self-consumption mode is the minimum, and the first selection circuit outputs the output target value in the self-consumption mode as the output target value of the inverter circuit. Therefore, the output of the inverter circuit is controlled to the output target value in the self-consumption mode, that is, the power consumption of the load. When the self-consumption mode is selected, the suppression circuit adds a predetermined value to the output limit value instructed by the electric utility, so that the output limit value after the addition is greater than the output target value for the self-consumption mode. Therefore, while the self-consumption mode is selected, the output target value output from the first selection circuit matches only the output target value for the self-consumption mode and does not match the output limit value to which the predetermined value has been added, so that it is possible to suppress the output of a notification command while the self-consumption mode is selected.

[0017] The suppression circuit may be a circuit including an adder that adds a predetermined value to an output limit value instructed by an electric utility company and outputs the result to the first selection circuit, and a switch in an input line of the predetermined value to the adder that turns on when the self-consumption mode is selected and turns off when the self-consumption mode is not selected.

[0018] In this configuration, the predetermined value is added to the output limit value only when the self-consumption mode is selected, and the predetermined value is not added when the self-consumption mode is not selected. Therefore, it is possible to suppress the output of a notification command during the self-consumption mode without affecting the output control of the inverter circuit when the self-consumption mode is not selected.

[0019] The control device may further include a voltage conversion unit that converts the output voltage of a solar power generation panel, which is the distributed power source, and outputs the converted output voltage to the inverter circuit, and the control device may include a second power control unit that performs MPPT control of the solar power generation panel, and a second selection circuit that selects the smaller of the operation amount for the voltage conversion unit from the first power control unit and the second power control unit, and outputs the selected operation amount to the voltage conversion unit, and the notification circuit may include a first judgment unit that judges whether an output target value output from the first selection circuit matches an output limit value input to the first selection circuit, a second judgment unit that judges whether an output value of the second selection circuit matches an operation amount output by the first power control unit, and an output unit that outputs a notification command when the output target value output from the first selection circuit matches the output limit value input to the first selection circuit and the output value of the second judgment circuit matches the operation amount output by the first power control unit.

[0020] The notification circuit outputs a notification command only when the output target value output from the first selection circuit matches the output limit value input to the first selection circuit and the output value of the second determination circuit matches the operation amount output by the first power control unit. In other words, even if the photovoltaic power generation panel is controlled to the maximum output by MPPT control, if the output of the inverter circuit is not limited to be less than the output limit value instructed by the electric utility (if the output value of the second determination circuit matches the operation amount output by the second power control unit), it is possible to suppress the output of the notification command.

[0021] <Embodiment 1> 1. Description of Microgrid S The microgrid S is a small-scale power system that is connected to a power system 1 operated by an electric power company, which is an electric utility company, and includes at least a distributed power source, a power control device, and a load.

[0022] 1 is a block diagram of a microgrid S. The microgrid S is made up of a photovoltaic power generation panel 10, which is a distributed power source, a power conditioner 20, which is a power control device, and a load L.

[0023] The power conditioner 20 includes a first current detection unit 21, a first voltage detection unit 22, a first converter circuit 23, a DC link unit 25, a DC voltage detection unit 27, a bidirectional inverter circuit 31, a second current detection unit 33, a second voltage detection unit 35, a relay 37, a control device 50, an operation unit 91, and an alarm unit 95.

[0024] The photovoltaic panel 10 is connected to the first converter circuit 23. The first converter circuit 23 is a DC / DC converter, which boosts and outputs the output voltage (direct current) of the photovoltaic panel 10. The first converter circuit 23 may be a boost chopper that boosts the voltage by switching. The first converter circuit 23 corresponds to the "voltage conversion unit" of the present invention.

[0025] The first current detection unit 21 and the first voltage detection unit 22 are located on the output side of the solar power generation panel 10. The first current detection unit 21 detects the output current Ipv of the solar power generation panel 10. The first voltage detection unit 22 detects the output voltage Vpv of the solar power generation panel 10.

[0026] The output current Ipv of the solar power generation panel 10 detected by the first current detection unit 21 and the output voltage Vpv of the solar power generation panel 10 detected by the first voltage detection unit 22 are input to the control device 50.

[0027] The control device 50 can calculate the output power Ppv [W] of the solar power generation panel 10 based on the output current Ipv and the output voltage Vpv of the solar power generation panel 10.

[0028] The first converter circuit 23 is connected to the bidirectional inverter circuit 31 via a DC link unit 25. The DC link unit 25 is provided with an electrolytic capacitor C1. The electrolytic capacitor C1 is provided to stabilize the voltage Vdc of the DC link unit 25.

[0029] The DC voltage detection unit 27 detects the voltage Vdc of the DC link unit 25. The voltage Vdc of the DC link unit 25 detected by the DC voltage detection unit 27 is input to the control device 50.

[0030] The bidirectional inverter circuit 31 is a bidirectional conversion circuit that selectively performs reverse conversion (inverter) that converts DC to AC and forward conversion (converter) that converts AC to DC. During reverse conversion operation, the bidirectional inverter circuit 31 converts DC power input from the DC link unit 25 into AC power and outputs it. In detail, power equivalent to the voltage increased from a reference value in the DC link unit 25 due to power generation by the solar power generation panel 10 is input to the bidirectional inverter circuit 31. Therefore, the power equivalent to the voltage increased from the reference value is converted from DC to AC and output from the bidirectional inverter circuit 31.

[0031] The bidirectional inverter circuit 31 is connected via a relay 37 to a power system 1 that uses a system power supply 2 as an AC power supply.

[0032] The relay 37 is provided for interconnection with the power grid 1. By closing the relay 37, the microgrid S can be interconnected with the power grid 1.

[0033] The second current detection unit 33 and the second voltage detection unit 35 are located on the output side of the bidirectional inverter circuit 31. The second current detection unit 33 detects the output current Iinv of the bidirectional inverter circuit 31. The second voltage detection unit 35 detects the output voltage Vinv of the bidirectional inverter circuit 31.

[0034] The output current Iinv of the bidirectional inverter circuit 31 detected by the second current detection unit 33 and the output voltage Vinv of the bidirectional inverter circuit 31 detected by the second voltage detection unit 35 are input to the control device 50.

[0035] The control device 50 calculates the output power (active power) Pinv of the bidirectional inverter circuit 31 based on the output current Iinv and the output voltage Vinv of the bidirectional inverter circuit 31. The output power Pinv is "positive" during inverse conversion and "negative" during forward conversion.

[0036] A load L, which is a demand facility, is connected to a power line (main line) 5 that connects the bidirectional inverter circuit 31 and the power system 1 via a branch line 4. Power can be supplied to the load L from both the power conditioner 20 and the power system 1.

[0037] The power receiving point 3 is a point where power is supplied from the power system 1 to the microgrid S, and is the boundary between the power system 1 and the microgrid S as shown in FIG.

[0038] The power system 1 is provided with an external measuring instrument 40 such as an external transducer as a meter for detecting power at the power receiving point 3.

[0039] The external measuring instrument 40 has a receiving current detection unit 41 and a system voltage detection unit 43. The external measuring instrument 40 is installed corresponding to the power receiving point 3, and the receiving current detection unit 41 detects the receiving current at the power receiving point 3. The system voltage detection unit 43 detects the system voltage of the power system 1.

[0040] The external measuring instrument 40 calculates the received power (active power) Pr of the microgrid S based on the receiving current and the system voltage. The received power Pr detected by the external measuring instrument 40 is input to the control device 50. The received power Pr can be used to determine the state of power flow (hereinafter simply referred to as flow). The external measuring instrument 40 is a measuring instrument that measures the received power Pr at the power receiving point 3.

[0041] With regard to received power Pr, forward flow (Figure 1: the flow of electricity from power grid 1 to microgrid S) is considered to be "positive" and reverse flow (Figure 2: the flow of electricity from microgrid S to power grid 1) is considered to be "negative."

[0042] The power consumption PL of the load L can be calculated from the received power Pr at the receiving point 3 and the output power Pinv of the bidirectional inverter circuit 31. In the case of forward power flow (Pr>0), the power consumption PL of the load L is the sum of the output power Pinv and the received power Pr. In the case of reverse power flow (Pr<0), the power consumption PL of the load L is the difference between the output power Pinv and the received power Pr.

[0043] PL=Pinv+Pr (1)

[0044] The control device 50 can control the switching between the forward conversion operation and the inverse conversion operation by giving a command to the bidirectional inverter circuit 31.

[0045] 2. Output control of solar panels The output of the solar power generation panel 10 varies depending on the solar radiation intensity, and the higher the solar radiation intensity, the higher the output.

[0046] 3 is a graph showing the output characteristics of the photovoltaic panel 10 for a certain solar radiation intensity. The vertical axis is power Ppv [W], current Ipv [A], and the horizontal axis is voltage Vpv [V]. La is the IV characteristic, and Lb is the PV characteristic. "Voc" is the open circuit voltage of the photovoltaic panel 10, and "Isc" is the short circuit current of the photovoltaic panel 10.

[0047] The power Ppv of the solar power panel 10 changes depending on the operating point M. When the operating point is M1, the power of the solar power panel 10 is "Ppv1." When the operating point is M2, the power of the solar power panel 10 is "Ppv2," which is lower than "Ppv1." In other words, by changing the operating point from M1 to M2, the output of the solar power panel 10 can be reduced by ΔP (ΔP=Ppv1-Ppv2). By changing the operating point from M2 to M1, the output of the solar power panel 10 can be increased by ΔP (ΔP=Ppv1-Ppv2).

[0048] The control device 50 can control the power Ppv [W] of the photovoltaic power generation panel 10 by controlling the operating point M via the first converter circuit 23. When the first converter circuit 23 is a boost chopper, the operating point M can be controlled by adjusting the output voltage Vco of the first converter circuit 23 through duty ratio control of the switching element. In other words, when the duty ratio of the switching element is reduced in accordance with the adjustment of the output voltage Vco, the current Ipv of the photovoltaic power generation panel 10 decreases, and when the duty ratio is increased, the current Ipv increases. When the current Ipv decreases, the operating point M moves to the right from its original position on the IV characteristic La in FIG. 3, and when the current Ipv increases, it moves to the left from its original position.

[0049] 3. Output Limitation and Self-Consumption Mode of Bidirectional Inverter Circuit (1) The output limit is, for example, performed at the request of an electric utility company, and limits the output of the bidirectional inverter circuit 31 according to an output limit schedule provided from the electric utility company's operation server 100 via the network NW. As shown in Fig. 4, the output limit schedule defines the output limit value [%] of the bidirectional inverter circuit 31 in units of time. The output limit value defines the upper limit of the output of the bidirectional inverter circuit 31, and in this example, is a ratio to the rated output [W] of the bidirectional inverter circuit 31. In other words, the output limit value for each time period is defined with the rated output = 100%.

[0050] In the example of Figure 4, the output limit value from 6:00 to 8:00 is 100[%], the output limit value from 8:00 to 9:00 is 50[%], the output limit value from 9:00 to 10:00 is 40[%], the output limit value from 10:00 to 11:00 is 20[%], and the output limit value from 11:00 to 15:00 is 0[%].

[0051] The output limit value from 3:00 p.m. to 4:00 p.m. is 20%; from 4:00 p.m. to 5:00 p.m. is 40%; from 5:00 p.m. to 6:00 p.m. is 50%; and from 6:00 p.m. to 8:00 p.m. is 100%.

[0052] The reason that the output limit value is low during times when the amount of power generated by the solar panel 10 is high (the reason that the output limit value is 0% during the time period from 11:00 to 15:00) is that the increase in reverse power flow from the microgrid S to the power grid 1 makes it necessary to suppress the voltage rise and frequency rise in the power grid 1.

[0053] The output limit is intended to limit the reverse power flow from the microgrid S to the power system 1, and does not apply to the output to the load L located within the premises of the microgrid S. In other words, even if the output limit value X2 is 0[%], the bidirectional inverter circuit 31 can output the power consumption PL [W] of the load L. For example, when the power consumption PL is 10 [W] and the output limit value X2 is 0[%], the bidirectional inverter circuit 31 can output up to 10 [W].

[0054] The control device 50 outputs notification information when the output target value X of the bidirectional inverter circuit 31 matches the output limit value X2. For example, when the output limit value X2 of the bidirectional inverter circuit 31 is 50[%] and the output target value X of the inverter circuit 31 is 50[%] of the rated output, the control device 50 outputs a notification command to the notification unit 95. The notification unit 95 is, for example, a lamp such as an LED, and turns on in response to the notification command.

[0055] The notification command is output in order to prevent the user (the operator of the microgrid S) from having any doubts about the fact that the output of the photovoltaic power generation panel 10 is lower than the expected output.

[0056] (2) The power conditioner 20 has a self-consumption mode as one of its functions. In the self-consumption mode, the power generated by the photovoltaic power generation panel 10 is consumed only by the load L in the microgrid S, and is not transmitted to the power grid 1. In the self-consumption mode, reverse power flow from the grid S to the power grid 1 is not permitted, and therefore the output target value X3 of the bidirectional inverter circuit 31 is zero. However, the output of the power consumption PL of the load L is permitted.

[0057] 5 is an example of a function setting screen of the power conditioner 20. The operation unit 91 is an operation panel 91A equipped with a display screen, and the function setting screen can be displayed on the screen of the operation panel 91A. The user can select whether to enable or disable "output restriction by electric power company" and "self-consumption mode" by operating the screen.

[0058] In this example, two buttons 92A, 93A are displayed below a display 92 of "output limitation by electric power company" and a display 93 of "self-consumption mode." Operating button 92A allows the user to enable "output limitation by electric power company." Operating button 93A allows the user to enable "self-consumption mode."

[0059] "Output limit by electric utility company" and "self-consumption mode" are coexisting functions, and it is possible to enable both "output limit by electric utility company" and "self-consumption mode" by turning on the two buttons 92A and 93A. It is possible to disable both "output limit by electric utility company" and "self-consumption mode" by turning off the two buttons 92A and 93A. It is also possible to enable only one of them and disable the other.

[0060] 4. Malfunction of control blocks and notification commands FIG. 6 shows an example of a control block 51 of the control device 50 that is related to power control of the photovoltaic power generation panel 10 and the bidirectional inverter circuit 31.

[0061] 6 includes a first comparator 61, a first power control unit 63, a second power control unit 65, a second comparator 67, and a notification circuit 70. The first comparator 61 corresponds to a "first selection circuit" of the present invention, and the second comparator 67 corresponds to a "second selection circuit" of the present invention.

[0062] The first comparator 61 determines the output target value X of the bidirectional inverter circuit 31. The first comparator 61 has three inputs and three input lines. The first input line L1 is for inputting the rated output [W] of the bidirectional inverter circuit 31, the second input line L2 is for inputting the output limit value of the bidirectional inverter circuit 31, and the third input line L3 is for inputting the output target value of the bidirectional inverter circuit 31 in the self-consumption mode.

[0063] The output limit value is provided by an operation server 100 of the electric utility company (see FIG. 4). The output limit value is expressed as a percentage with the rated output being 100%.

[0064] The output target value in self-consumption mode is expressed as a percentage of the rated output, with 100% as the percentage. Self-consumption mode is a mode that does not allow reverse power flow from grid S to power system 1, and the output target value X3 is 0% of the rated output. However, as mentioned above, the output of power consumption PL of load L, which corresponds to self-consumption, is permitted.

[0065] The magnitude relationship between the output limit value X2 of the bidirectional inverter circuit 31 provided by the electric utility, the output target value X3 in the self-consumption mode, and the rated output X1 of the bidirectional inverter circuit 31 is as follows, assuming that the rated output X1 = 100 [%].

[0066] X3≦X2≦X1 (2) X3=0 (3)

[0067] 4, the output limit value X2=0, so that X2=X3. In other time periods, the output limit value X2>0, so that X2>X3.

[0068] A switch SW is provided on the input line L3 for the output target value X3 in the self-consumption mode. The switch SW is turned on only when the user selects the self-consumption mode, and is turned off otherwise.

[0069] The first comparator 61 compares the magnitudes of three input values, namely, the rated output X1 [%], the output limit value X2 [%], and the self-consumption mode output target value X3 [%], and outputs the smallest input value X. If X3 has not been input, the first comparator 61 outputs the smaller input value X between the rated output X1 and the output limit value X2.

[0070] The output X of the first comparator 61 is the output target value of the bidirectional inverter circuit 31 , and is output to the first power control unit 63 .

[0071] The first power control unit 63 is for controlling the output of the bidirectional inverter circuit 31. The first power control unit 63 receives the current manipulated variable Y, the output target value X output from the first comparator 61, and the output Pinv of the bidirectional inverter circuit 31. The first power control unit 63 calculates and outputs a first manipulated variable Y1 based on the deviation between the output target value X and the output Pinv. The first manipulated variable Y1 is a manipulated variable increase / decrease value (ΔY) that needs to be further adjusted with respect to the current manipulated variable Y in order to reduce the deviation.

[0072] The first manipulated variable Y1 is an adjustment amount of the output voltage Voc of the first converter circuit 23. The first power control unit 63 controls the output of the photovoltaic power generation panel 10 by adjusting the output voltage Voc of the first converter circuit 23, thereby controlling the output of the bidirectional inverter circuit 31 to the output target value X.

[0073] The first manipulated variable Y1 is determined as a manipulated variable that can secure the power consumption PL of the load L with the output of the bidirectional inverter circuit 31, regardless of the output target value X output from the first comparator 61. The power consumption PL can be calculated from the above formula (1).

[0074] The second power control unit 65 is for MPPT. MPPT (maximum power point tracking control) is control for making the operating point M on the IV characteristic La shown in Fig. 3 follow the optimal operating point. The optimal operating point is an operating point where the output Ppv of the photovoltaic power generation panel 10 is the maximum output, for example, "M1".

[0075] The second power control unit 65 receives the current operation amount Y and the output Ppv of the solar power generation panel 10. Based on the output Ppv of the solar power generation panel 10, the second power control unit 65 calculates and outputs a second operation amount Y2 that causes the operating point M on the I-V characteristic La to follow the optimal operating point M1. The second operation amount Y2 is an operation amount increase / decrease value (ΔY) that requires further adjustment with respect to the current operation amount Y in order to cause the operating point M to follow the optimal operating point M1.

[0076] Since MPPT is performed by adjusting the output voltage of the first converter circuit 23, the second operation amount Y2 is, like the first operation amount Y1, an adjustment amount of the output voltage Voc of the first converter circuit 23.

[0077] The second comparator 67 has two inputs, and the first operation amount Y1 determined by the first power control unit 63 and the second operation amount Y2 determined by the second power control unit 65 are input.

[0078] The second comparator 67 compares the magnitudes of the two input values, that is, the first operation amount Y1 and the second operation amount Y2, and outputs the smaller operation amount Y to the first converter circuit 23.

[0079] When Y2 < Y1, since the output voltage Voc of the first converter circuit 23 is controlled by the second operation amount Y2 for MPPT, the solar power generation panel 10 maintains the maximum output by MPPT control.

[0080] When Y1 < Y2, since the output voltage Voc of the first converter circuit 23 is controlled by the first operation amount Y1 for power control, the output of the bidirectional inverter circuit 31 is adjusted to maintain the output target value X, and the output Ppv of the solar power generation panel 10 is in a state where the output is restricted even if there is a margin with respect to the maximum output.

[0081] When Y1 < Y2 (when the first operation amount Y1 is selected as the operation amount Y of the first converter circuit 23), and when the output target value X of the bidirectional inverter circuit 31 matches the output limit value X2 instructed by the electric utility, the notification circuit 70 outputs a notification command to the notification unit 95. That is, if the operating point M of the solar power generation panel 10 is changed, the bidirectional inverter circuit 31 can output a higher output, but when the output target value X is restricted to the output limit value X2 instructed by the electric utility, it is a circuit that outputs a notification command.

[0082] The notification circuit 70 includes a first determination unit 71, a second determination unit 73, and an AND circuit 75. The AND circuit 75 is an example of the "output unit" of the present invention.

[0083] The output target value X of the bidirectional inverter circuit 31 output from the first comparator 61 is input to the first determination unit 71. The first determination unit 71 compares the output target value X of the bidirectional inverter circuit 31 with the input value input to the first comparator 61 through the input line L2, and determines whether the output target value X matches the input value. The input line L2 is an input line for the output limit value X2 provided by the electric utility.

[0084] When the output target value X of the bidirectional inverter circuit 31 output from the first comparator 61 matches the input value "X2" input to the first comparator 61 through the input line L2 (when X = X2), the first determination unit 71 outputs "1" to the AND circuit 75, and outputs "0" in the case of a mismatch.

[0085] The operation amount Y output from the second comparator 67 is input to the second determination unit 73. The second determination unit 73 compares the operation amount Y output from the second comparator 67 with the first operation amount Y1 output from the first power control unit 63, and determines whether the operation amount Y matches the first operation amount Y1.

[0086] The second judgment unit 73 outputs "1" to the AND circuit 75 if the operation amount Y output from the second comparator 67 matches the first operation amount Y1 (if Y=Y1), and outputs "0" if they do not match.

[0087] The AND circuit 75 outputs a notification command to the notification unit 95 when the output of the first determination unit 71 is “1” and the output of the second determination unit 73 is also “1”.

[0088] When the output of the first determination unit 71 is "1", the output target value X output from the first comparator 61 is the output limit value X2 provided by the electric utility company (X=X2).

[0089] When the output of the second determination unit 73 is “1”, the bidirectional converter circuit 31 is controlled by the output target value X of the first comparator 61 .

[0090] Therefore, when the output of the first judgment unit 71 is “1” and the output of the second judgment unit 73 is also “1”, the output target value X of the bidirectional inverter circuit 31 matches the output limit value X2 provided by the electric utility, and it can be determined that the power conditioner 20 is undergoing output limiting at the request of the electric utility (Y=Y1, X=X2).

[0091] For example, if the output limit value X2 provided by the electric utility company is 10% of the rated output, a higher output can be achieved by changing the operating point M of the solar power generation panel 10, but the output target value X of the power conditioner 20 is limited to 10% of the rated output due to the output limit requested by the electric utility company.

[0092] When the output target value X of the bidirectional inverter circuit 31 matches the output limit value X2, that is, when the power conditioner 20 is limiting the output at the request of the electric utility, a notification command is issued and a notification lamp or the like is turned on to inform the user that "the power conditioner 20 is limiting the output."

[0093] Since the self-consumption mode is a mode that the user selects himself / herself to limit the output, there is no need to "issue a notification command and turn on a notification lamp, etc."

[0094] However, when both the "self-consumption mode" and the "output limit by the electric power company" are enabled, if the output target value X3 in the self-consumption mode matches the output limit value X2 provided by the electric power company, it is not possible to determine whether the output target value X output from the first comparator 61 is "X2" or "X3," and there is a possibility that the AND circuit 75 will erroneously output an "alert command."

[0095] For example, if the output limit value X2 requested by the electric power supplier is 0[%], similar to the output target value X3 in the self-consumption mode, then X2=X3.

[0096] In this case, during selection of the self-consumption mode, the first judgment unit 71 may erroneously judge that X=X2 instead of X=X3, resulting in the output of the first judgment unit 71 becoming "1." As a result, there is a possibility that the AND circuit 75 may erroneously output the "notification command."

[0097] FIG. 7 shows an example of a control block 51 of the control device 50 that is related to power control of the photovoltaic power generation panel 10 and the bidirectional inverter circuit 31.

[0098] The second control block 51B shown in FIG. 7 includes a first comparator 61, a first power control unit 63, a second power control unit 65, a second comparator 67, a first judgment unit 71, a second judgment unit 73, an AND circuit 75, and a suppression circuit 80.

[0099] The second control block 51B is the same as the first control block 51A except that a suppression circuit 80 is added.

[0100] The suppression circuit 80 includes an adder 81, a signal generator 83, and an interlocking switch SWb. The adder 81 is provided on the second input line L2 of the first comparator 61. The second input line L2 is an input line for the output limit value X2.

[0101] A signal generator 83 is connected to the adder 81. The signal generator 83 outputs a predetermined value K. The predetermined value K is a positive constant, and is, for example, 1[%].

[0102] The interlock switch SWb is located on the input line L4 of a predetermined value K, and is an interlock switch that turns on and off in conjunction with the switch SWa on the third input line L3.

[0103] When the self-consumption mode is selected and the switch SWa is turned on, the switch SWb is also turned on in conjunction with the self-consumption mode. When the switch SWb is turned on, the adder 81 outputs the output limit value X2a obtained by adding a predetermined value K output by the signal generator 83 to the output limit value X2.

[0104] X2a = X2 + K (4) For example, K is "1".

[0105] By inputting the output limit value X2a, which is the output limit value X2 plus a predetermined value K, to the first comparator 61, it is possible to prevent the AND circuit 75 from erroneously outputting a "notification command" while the self-consumption mode is selected, even if the output limit value X2 provided by the electric utility matches the output target value X3 of the self-consumption mode.

[0106] Specifically, when the self-consumption mode is selected, the output limit value X2 at the request of the electric power company is input to the first comparator 61 after a predetermined value "1" is added thereto.

[0107] Therefore, as shown in FIG. 8, when the output limit value X2 requested by the electric utility is 0% like the output target value X3, the output limit value X2a input to the first comparator 61 via the second input line L2 is “1”.

[0108] In this case, the three inputs to the first comparator 61 are X1=100, X2a=1, and X3=0, and the output X of the first comparator 61 is "0", so X≠X2a and the first judgment unit 71 outputs "0" to the AND circuit 75. Therefore, it is possible to suppress the output of a notification command from the AND circuit 75.

[0109] <Other embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included within the technical scope of the present invention.

[0110] (1) Distributed power sources are a general term for small-scale power generation facilities that are distributed and located adjacent to demand areas. Distributed power sources are not limited to solar power generation panels 10, and may be wind power generation or biomass power generation devices. If the distributed power source is AC, it is recommended that it be connected to the first converter circuit 23 via a rectifier. The distributed power source may be a power source that uses renewable energy or a power source that uses fossil fuels.

[0111] (2) In the embodiment, a grid having linear power lines (trunk lines) 5 is shown as an example of the microgrid S. However, a grid having circular power lines (trunk lines) may also be used.

[0112] (3) In this embodiment, when the self-consumption mode is selected, "1" is added to the output limit value X2 provided by the electric utility company, thereby preventing the erroneous output of a notification command while the self-consumption mode is selected. The value added to the output limit value X2 may be any positive number other than "1". "1" may be added to the output limit value X2 for all target times specified as the output limit schedule provided by the electric utility company, or "1" may be added only when the output limit value X2 is "0" (the time period from 11:00 to 15:00 shown in FIG. 4).

[0113] (4) In this embodiment, the first control block 51A includes the first comparator 61, the first power control unit 63, the second power control unit 65, the second comparator 67, and the notification circuit 70. The first control block 51A may not include the second power control unit 65 and the second comparator 67 as long as it includes at least the first comparator 61, the first power control unit 63, and the notification circuit 70. For example, if the distributed power source is other than a solar panel, the second power control unit 65 and the second comparator 67 may not be included. The notification circuit 70 may include only the first determination unit 71, and may output a notification command under the condition of X=X2. The same applies to the second control block 51B.

[0114] (5) In this embodiment, the lamp is turned on in response to a notification command output from the notification circuit 70. In response to the notification command, a buzzer may be sounded, or a message such as "output restriction is in progress" may be displayed. Any method of notification may be used.

[0115] (6) In this embodiment, the inverter circuit 31 is bidirectional, but it is sufficient if it is capable of inversely converting DC to AC.

[0116] (7) In this embodiment, the output target value X3 in the self-consumption mode is set to "0", but the output target value X3 may be other than "0". It is sufficient that the formula (2) is satisfied in relation to the rated output X1 and the output limit value X2. In this embodiment, the power consumption PL of the load L is not included in the output target value X3 numerically, but it may be included. For example, if the power consumption PL of the load L is 10% of the rated output, the output target value X3 in the self-consumption mode may be set to "10%" instead of "0". When the power consumption PL of the load L is included in the output target value X3, it is preferable to similarly include the power consumption PL in the output limit value X2 provided by the electric power supplier.

[0117] (8) Fig. 9 is a block diagram of a power control system 200. The power control system 200 includes a power conditioner 210, a control device 250, an operation unit 91, and a notification unit 95. The power conditioner 210 is a power conversion device, and includes a first current detection unit 21, a first voltage detection unit 22, a first converter circuit 23, a DC link unit 25, a DC voltage detection unit 27, a bidirectional inverter circuit 31, a second current detection unit 33, a second voltage detection unit 35, and a relay 37.

[0118] 9 differs from the power conditioner 20 in Fig. 1 in that the "control device 250", "operation unit 91", and "notification unit 95" are separate devices. The control device 250 is connected to the power conditioner 210 via a network or a communication line, and remotely controls the power conditioner 210. The control device 250 includes a control block 51.

[0119] The control block 51 may be a first control block 51A shown in Fig. 6 or a second control block 51B shown in Fig. 7. The second control block 51B includes a suppression circuit 80 in addition to a first comparator 61, a first power control unit 63, a second power control unit 65, a second comparator 67, a first judgment unit 71, a second judgment unit 73, and an AND circuit 75. By including the suppression circuit 80, it is possible to suppress the AND circuit 75 from erroneously outputting a "notification command" when the output target value X3 during the self-consumption mode coincides with the output limit value X2 provided by the electric utility company.

[0120] (9) This technology is not limited to microgrids (small-scale power systems) and can be applied to any grid (power system) that is connected to a power system 1 operated by an electric power company. [Explanation of symbols]

[0121] 1 Power system 2 power supplies 3 Receiving point 10. Photovoltaic power generation panel (an example of the "distributed power source" of the present invention) 20 Power conditioner (an example of the "power control device" of the present invention) 31 Bidirectional inverter circuit 50 Control device 51A First control block 51B Second control block 61 First comparator (an example of the "first selection circuit" of the present invention) 63 First power control section 65 Second Power Control Section 67 Second comparator (an example of the "second selection circuit" of the present invention) 70 Alarm circuit 71 1st judgment part 73 Second judgment part 75 AND circuit (an example of the "output section" of the present invention) S Microgrid

Claims

1. A power control device for a grid that is equipped with distributed power sources and is connected to a power system, comprising: an inverter circuit that converts the power supplied from the distributed power sources from direct current to alternating current and outputs the converted power; a control device for controlling an output of the inverter circuit; The control device includes: a first selection circuit that selects the smallest value of three input values, which are a rated output of the inverter circuit, an output target value in a self-consumption mode, and an output limit value instructed by an electric utility that is equal to or greater than the output target value in the self-consumption mode, and outputs the smallest value as the output target value of the inverter circuit; a first power control unit that controls an output of the inverter circuit in accordance with an output target value output from the first selection circuit; a notification circuit that outputs a notification command when the output target value output from the first selection circuit coincides with the output limit value input to the first selection circuit; A power control device comprising: a suppression circuit that, when the self-consumption mode is selected, suppresses the notification command from being output while the self-consumption mode is selected by adding a predetermined value to an output limit value instructed by an electric power company.

2. 2. The power control device according to claim 1, The suppression circuit includes: an adder that adds a predetermined value to an output limit value instructed by an electric utility company and outputs the result to the first selection circuit; a switch, in a predetermined value input line to the adder, which is turned on when the self-consumption mode is selected and turned off when the self-consumption mode is not selected.

3. The power control device according to claim 1 or 2, a voltage conversion unit that converts an output voltage of a solar power generation panel that is the distributed power source and outputs the converted output voltage to the inverter circuit, The control device includes: A second power control unit that controls the solar power generation panel in an MPPT manner; a second selection circuit that selects one of the first power control unit and the second power control unit, which has a smaller operation amount for the voltage conversion unit, and outputs the selected operation amount to the voltage conversion unit, The notification circuit includes: a first determination unit that determines whether or not an output target value output from the first selection circuit matches an output limit value input to the first selection circuit; a second determination unit that determines whether or not an output value of the second selection circuit coincides with an operation amount output by the first power control unit; a control device that outputs a notification command when an output target value output from the first selection circuit matches an output limit value input to the first selection circuit and an output value of the second selection circuit matches an operating amount output by the first power control unit.

4. A power control system for a grid having distributed power sources and connected to a power system, comprising: A power conversion device including an inverter circuit that converts the power supplied from the distributed power sources from DC to AC and outputs the converted power; a control device; The control device includes: a first selection circuit that selects the smallest value of three input values, which are a rated output of the inverter circuit, an output target value in a self-consumption mode, and an output limit value instructed by an electric utility that is equal to or greater than the output target value in the self-consumption mode, and outputs the smallest value as the output target value of the inverter circuit; a first power control unit that controls an output of the inverter circuit in accordance with an output target value output from the first selection circuit; a notification circuit that outputs a notification command when the output target value output from the first selection circuit coincides with the output limit value input to the first selection circuit; and a suppression circuit that, when the self-consumption mode is selected, suppresses the notification command from being output while the self-consumption mode is selected by adding a predetermined value to an output limit value instructed by an electric utility company.

5. A power control device, An inverter circuit that converts the power supplied from the distributed power source from direct current to alternating current and outputs the converted power; a control device for controlling an output of the inverter circuit; The control device includes: a first selection circuit that, when an output target value in a self-consumption mode and an output limit value instructed by an electric utility that is equal to or greater than the output target value in the self-consumption mode are input, selects the smallest input value and outputs it as the output target value of the inverter circuit; a notification circuit that outputs a notification command when the output target value output from the first selection circuit matches the output limit value input to the first selection circuit, A power control device that adds a predetermined value to an output limit value instructed by an electric utility company when a self-consumption mode is selected.

6. A power control system, comprising: A power conversion device including an inverter circuit that converts power supplied from a distributed power source from direct current to alternating current and outputs the converted power; a control device; The control device includes: a first selection circuit that, when an output target value in a self-consumption mode and an output limit value instructed by an electric utility that is equal to or greater than the output target value in the self-consumption mode are input, selects the smallest input value and outputs it as the output target value of the inverter circuit; a notification circuit that outputs a notification command when the output target value output from the first selection circuit matches the output limit value input to the first selection circuit, A power control system that adds a predetermined value to the output limit value instructed by the electric utility when the self-consumption mode is selected.

Images