Power controller, grid, power control method, and control device

Abstract

To provide a power controller for effectively utilizing generated power of a distributed type power supply by suppressing charge-starting failure of surplus power, and provide a grid thereof.SOLUTION: A power controller of a grid S interconnecting with a power system 1 comprising a distributed power supply 10 and a power storage device comprises a first adjustment unit 21 for adjusting an output of the distributed power supply, a second adjustment unit 23 for adjusting charging / discharging of the power storage device, an inverter circuit 31 for converting power supplied from the distributed power supply and the power storage device from DC into AC to be output to a load, and a control device 50. The control device executes a first control for controlling the output of the distributed power supply with the first adjustment unit in such a manner that reception power of the grid becomes a first target value, and a second control for charging the power storage device via the second adjustment unit with surplus power of the distributed power supply in such a manner that the reception power of the grid becomes a second target value; and starts the second control, when the reception power of the grid is lowered to a determination value. The determination value at which the second control is started is the first target value or greater.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a technology for effectively utilizing the energy of distributed power sources.

Background Art

[0002] From the viewpoints of reducing dependence on fossil fuels and environmental problems, the introduction of distributed power sources typified by photovoltaic (PV) systems has been promoted. The PV system converts the power generated by the solar power generation panel from direct current to alternating current using the inverter circuit of the power control device and outputs it.

[0003] Patent Document 1 below discloses a power storage type photovoltaic power generation system including a solar cell, a storage battery, a reverse current prevention diode, a power conditioner, a load, and the like.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] To maintain power quality, it is preferable to suppress the reverse power flow from the grid to the power system. To suppress the reverse power flow to the power system, it is conceivable to control the output of the distributed power source so that the received power from the grid becomes equal to or higher than the first target value.

[0006] To effectively utilize the energy of the distributed power source, when there is an excess of power in the distributed power source, it is conceivable to charge the storage device with the excess power. When the received power decreases to the determination value as the output of the distributed power source increases, it is conceivable to determine that there is excess power in the distributed power source and start charging the storage device.

[0007] However, in order to suppress the reverse power flow, since the received power is maintained at or above the first target value, if the determination value is smaller than the first target value, the charging of the energy storage device may never start, and the generated power of the distributed power source may be wasted.

[0008] This technology discloses a technology for suppressing poor charging start and effectively utilizing the generated power of a distributed power source.

Means for Solving the Problem

[0009] A power control device of a grid that includes a distributed power source and an energy storage device and is connected to a power system includes a first adjustment unit that adjusts the output of the distributed power source, a second adjustment unit that adjusts the charge and discharge of the energy storage device, an inverter circuit that converts the power supplied from the distributed power source and the energy storage device from DC to AC and outputs it, and a control device. The control device performs a first control to control the output of the distributed power source by the first adjustment unit so that the received power of the grid becomes a first target value, and a second control to charge the surplus power of the distributed power source to the energy storage device via the second adjustment unit so that the received power of the grid becomes a second target value. When the received power from the power system to the grid drops to a first determination value, the control device starts the second control, and the first determination value for starting the second control is equal to or greater than the first target value.

[0010] This technology can be applied to a grid connected to a power system.

Effect of the Invention

[0011] It is possible to suppress poor charging start of surplus power and effectively utilize the generated power of the distributed power source.

Brief Description of the Drawings

[0012]

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Mode for Carrying Out the Invention

[0013] A power control device for a grid that includes a distributed power source and a power storage device and is connected to a power system includes a first adjustment unit that adjusts the output of the distributed power source, a second adjustment unit that adjusts the charge and discharge of the power storage device, an inverter circuit that converts the power supplied from the distributed power source and the power storage device from direct current to alternating current and outputs it, and a control device. The control device performs a first control of controlling the output of the distributed power source by the first adjustment unit so that the received power of the grid becomes a first target value, and a second control of charging the surplus power of the distributed power source into the power storage device via the second adjustment unit so that the received power of the grid becomes a second target value. When the received power from the power system to the grid drops to a first determination value, the control device starts the second control, and the first determination value for starting the second control is equal to or greater than the first target value.

[0014] The received power of the grid is maintained at or above a first target value by the first control, and varies within a range of at least the first target value as the output of the distributed power source increases or decreases. By setting the first determination value to be equal to or greater than the first target value, when the output of the distributed power source increases, the received power decreases and falls below the first determination value, enabling the charging of the energy storage device to start. Therefore, it is possible to suppress poor start of charging and charge the surplus power of the distributed power source to the energy storage device.

[0015] The second target value may be greater than the first target value. This configuration can create a cycle of repeating "charging of surplus power" by the energy storage device and "increase in output" of the distributed power source, so that the surplus power of the distributed power source can be efficiently charged to the energy storage device.

[0016] The magnitude relationship among the first target value, the second target value, and the first determination value may be the first target value ≤ the first determination value < the second target value. In this configuration, since "first target value" ≤ "first determination value", it is possible to suppress poor start of charging. Since "first determination value" < "second target value", at the start time of charging (received power = determination value), second target value - received power > 0, and the power difference (second target value - received power) can be used as surplus power to charge the energy storage device.

[0017] Since "first target value" < "second target value", it is possible to create a cycle of repeating "charging of surplus power" by the energy storage device and "increase in output" of the distributed power source, so that the surplus power of the distributed power source can be efficiently charged to the energy storage device.

[0018] <Embodiment 1> 1. Description of Microgrid S The microgrid S is a small-scale power system connected to the power grid 1, and includes at least a distributed power source, an energy storage device, and a load. The power grid 1 may be that of a power utility or an independent power grid composed of the self-operating output of a large power conditioner.

[0019] FIG. 1 is a block diagram of the microgrid S. The microgrid S is composed of a solar power generation panel 10 which is a distributed power source, a storage battery 15 which is a power storage device, a power conditioner 20 which is a power control device, and a load L.

[0020] The power conditioner 20 includes a first converter circuit 21, a second converter circuit 23, a DC link section 25, a bidirectional inverter circuit 31, a relay 37, a control device 50, a DC voltage detection section 27, an output current detection section 33, and an output voltage detection section 35.

[0021] The solar power generation panel 10 is connected to the first converter circuit 21. The first converter circuit 21 is a DC / DC converter and boosts and outputs the output voltage (DC) of the solar power generation panel 10. The first converter circuit 21 may be a chopper. The first converter circuit 21 corresponds to the "first adjustment unit" of the present invention.

[0022] The storage battery 15 is connected to the second converter circuit 23. The storage battery 15 is, for example, a secondary battery. The second converter circuit 23 is a bidirectional DC / DC converter that discharges and charges the storage battery 15. The second converter circuit 23 may be a bidirectional chopper. The second converter circuit 23 corresponds to the "second adjustment unit" of the present invention.

[0023] The solar power generation panel 10 and the storage battery 15 are connected in parallel to the DC link section 25 via the first converter circuit 21 and the second converter circuit 23.

[0024] The DC link section 25 is located between the connection point 24 of the converter circuits 21, 23 and the bidirectional inverter circuit 31. An electrolytic capacitor C1 is provided in the DC link section 25. The electrolytic capacitor C1 is provided to stabilize the voltage Vdc of the DC link section 25.

[0025] 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.

[0026] The bidirectional inverter circuit 31 is a bidirectional conversion circuit that selectively performs an inverse conversion (inverter) that converts DC to AC and a forward conversion (converter) that converts AC to DC. The bidirectional inverter circuit 31 is connected to the DC link unit 25, and during the inverse conversion operation, it converts the DC power input from the DC link unit 25 into AC power and outputs it. Specifically, the bidirectional inverter circuit 31 receives power corresponding to the voltage increase in the DC link unit 25 above the reference value due to the power generation of the solar power generation panel 10. Therefore, the power corresponding to the voltage increase above the reference value is converted from DC to AC and output from the bidirectional inverter circuit 31.

[0027] The storage battery 15 can store the surplus power of the solar power generation panel 10 via the second converter circuit 23. When the power generation power of the solar power generation panel 10 is insufficient, the storage battery 15 can discharge via the second converter circuit 23 to compensate for the shortage of power generation power.

[0028] The bidirectional inverter circuit 31 is connected to the power grid 1 using the utility power 2 as an AC power source via the relay 37.

[0029] The relay 37 is installed for connection with the power grid 1. By closing the relay 37, the microgrid S can be connected to the power grid 1.

[0030] The output current detection unit 33 detects the output current Iinv of the bidirectional inverter circuit 31. The output voltage detection unit 35 is located on the output side of the bidirectional inverter circuit 31 and detects the output voltage Vinv of the bidirectional inverter circuit 31.

[0031] The output current Iinv of the bidirectional inverter circuit 31 detected by the output current detection unit 33 and the output voltage Vinv of the bidirectional inverter circuit 31 detected by the output voltage detection unit 35 are input to the control device 50. 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 set to "positive" during the inverse conversion and "negative" during the forward conversion.

[0032] 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 grid 1 via a branch line 4. Power can be supplied to the load L from both the power conditioner 20 and the power grid 1.

[0033] The power receiving point 3 is a point where power is supplied from the power grid 1 to the microgrid S, and as shown in FIG. 1, it is a boundary portion between the power grid 1 and the on-site area (microgrid S).

[0034] An external measuring instrument 40, such as an external transducer, is provided in the power grid 1 as an instrument for detecting the power at the power receiving point 3.

[0035] The external measuring instrument 40 has a power 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. The power receiving current detection unit 41 detects the power receiving current at the power receiving point 3. The system voltage detection unit 43 detects the system voltage of the power grid 1.

[0036] The external measuring instrument 40 calculates the power received by the microgrid S (active power) Pr based on the power receiving current and the system voltage. The detected power received Pr by the external measuring instrument 40 is input to the control device 50. The power received Pr can be used for determining the state of the power flow (hereinafter simply referred to as the flow). The external measuring instrument 40 is an instrument that measures the power received Pr at the power receiving point 3.

[0037] The received power Pr is defined such that the forward power flow (the flow of electricity from the power system 1 towards the microgrid S in FIG. 1) is "positive" and the reverse power flow (the flow of electricity from the microgrid S towards the power system 1 in FIG. 2) is "negative".

[0038] The power consumption PL of the load L can be obtained from the received power Pr at the power reception 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 (see FIGS. 6 and 7). 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.

[0039] PL = Pinv + Pr (1)

[0040] The control device 50 includes a CPU 51 and a memory 53. The memory 53 stores the control program of the power conditioner 20 and the data necessary for the execution of the program. The control program includes the execution program of the first control shown in FIG. 4 and the execution program of the second control shown in FIG. 8.

[0041] The control device 50 can control the switching between the forward conversion operation and the reverse conversion operation by giving commands to the bidirectional inverter circuit 31.

[0042] The control device 50 can control the output power P [W] of the solar power generation panel 10 via the first converter circuit 21.

[0043] The output characteristics of the solar power generation panel 10 vary depending on the solar radiation intensity. The higher the solar radiation intensity, the higher the output. The power generation upper limit value of the solar power generation panel 10 is the maximum output at the maximum solar radiation intensity.

[0044] FIG. 3 is a graph showing the output characteristics of the solar power generation panel 10 for an arbitrary solar radiation intensity. The vertical axis represents power P [W], current I [A], and the horizontal axis represents voltage V [V]. L1 is the I-V characteristic, and L2 is the P-V characteristic. "Voc" is the open-circuit voltage of the solar power generation panel 10, and "Isc" is the short-circuit current of the solar power generation panel 10.

[0045] The power P of the photovoltaic panel 10 changes according to the operating point M. When the operating point is M1, the power of the photovoltaic panel 10 is "Pw1". When the operating point is M2, the power of the photovoltaic panel 10 is a power "Pw2" lower than "Pw1". That is, by changing the operating point from M1 to M2, the output of the photovoltaic panel 10 can be limited (ΔP = Pw1 - Pw2). By changing the operating point from M2 to M1, the output of the photovoltaic panel 10 can be increased by ΔP (ΔP = Ppv1 - Ppv2).

[0046] The control device 50 can control the power Ppv [W] of the photovoltaic panel 10 by controlling the operating point M via the first converter circuit 21. When the first converter circuit 21 is a boost chopper, the operating point M can be controlled by controlling the duty ratio of the switching element. For example, by reducing the duty ratio and restricting the current, the voltage of the photovoltaic panel 10 increases, and the operating point M moves to the right from its original position on the I-V characteristic L1 in FIG. 3. Conversely, by increasing the duty ratio and increasing the current, the voltage of the photovoltaic panel 10 drops, and the operating point M moves to the left from its original position on the I-V characteristic L1 in FIG. 3.

[0047] The control device 50 can control the charging power [W] charged from the photovoltaic panel 10 to the storage battery 15 via the second converter circuit 23. Furthermore, the discharge power [W] discharged from the storage battery 15 to the second converter circuit 23 can be controlled. The control of the charging power may control the charging current by the second converter circuit 23, or may control the charging voltage. The control of the discharge power is the same.

[0048] 2. Suppression of reverse power flow and charging of surplus power In order to maintain the electrical quality of the power system 1, it is desirable not to cause reverse power flow from the microgrid S to the power system 1.

[0049] The control device 50 executes the first control to suppress reverse power flow.

[0050] Figure 4 is a flowchart of the first control. The first control is constantly executed at a predetermined cycle while the output of the solar power generation panel 10 is being generated. The first control consists of seven steps S10 to S70.

[0051] At S10, the control device 50 monitors the received power Pr based on the output value of the measuring device 40. At S20, the control device 50 compares the received power Pr with the first target value P1 and determines whether it is greater than the first target value P1.

[0052] If the received power Pr is greater than the first target value P1, the process proceeds to S30. When the process proceeds to S30, the control device 50 controls the operating point M of the solar power generation panel 10 to the maximum output point M1 by the first converter circuit 21. As a result, the solar power generation panel 10 is controlled to its maximum output according to the solar irradiance at that time. Then, the process proceeds to S10 and the received power Pr is detected.

[0053] If the received power Pr is greater than the first target value P1, since S10 to S30 are repeated, the solar power generation panel 10 maintains its maximum output.

[0054] The output of the solar power generation panel 10 increases as the solar irradiance increases. As the output of the solar power generation panel 10 increases with the increase in solar irradiance, the received power Pr decreases. Here, the case where there is no variation in the load L and the storage battery 15 is stopped is being described. The load L may vary.

[0055] During the execution of the first control, when the received power Pr becomes less than or equal to the first target value P1, a NO determination is made at S20 and the process proceeds to S40. When the process proceeds to S40, the control device 50 detects the difference P1 - Pr between the received power Pr and the first target value P1.

[0056] After that, it proceeds to S50, and the control device 50 determines the sign of the detected difference (P1 - Pr). If P1 - Pr > 0, it proceeds to S60. When it proceeds to S60, the control device 50 controls the operating point M of the solar power generation panel 10 to reduce the output of the solar power generation panel 10. Due to the decrease in the output of the solar power generation panel 10, the received power Pr increases and approaches the first target value P1.

[0057] If P1 - Pr ≤ 0, it proceeds to S70. When it proceeds to S70, the control device 50 controls the operating point M of the solar power generation panel 10 to increase the output of the solar power generation panel 10. Due to the increase in the output of the solar power generation panel 10, the received power Pr decreases and approaches the first target value P1. As described above, the received power Pr can be controlled to the first target value P1.

[0058] FIG. 5 is a graph showing the relationship between the power supply and demand of the microgrid S. The load power PL is constant. The solar power generation panel 10 starts output at time t0, and after that, the output PPV of the solar power generation panel 10 increases. The received power Pr decreases after the time t0 when the solar power generation panel 10 starts output, and decreases to the first target value P1 at time t1.

[0059] After the time t1 when the received power Pr decreases to the first target value P1, the output PPV of the solar power generation panel 10 is limited to a predetermined value (PL - P1) by adjusting the operating point M. Thereby, after the time t1, the received power Pr is maintained at the first target value P1.

[0060] That is, after the time t1 when the output PPV of the solar power generation panel 10 exceeds the predetermined value (PL - P1), it can be considered that surplus power is generated in the solar power generation panel 10 (shown by the broken line in FIG. 5). By charging the surplus power into the storage battery 15, the generated power of the solar power generation panel 10 can be effectively utilized (FIGS. 6 and 7).

[0061] The control device 50 executes the second control to charge the surplus power of the solar power generation panel 10.

[0062] FIG. 8 is a flowchart of the second control. The second control is constantly executed at a predetermined cycle while the output of the solar power generation panel 10 is being generated. The second control consists of six steps from S110 to S160.

[0063] In S110, the control device 50 monitors the received power Pr based on the output value of the measuring device 40. In S120, the control device 50 compares the received power Pr with a first determination value PX. The first determination value PX is a value for determining the presence or absence of surplus power of the solar power generation panel 10. When the load L is constant, as the output of the solar power generation panel 10 increases, the received power Pr decreases. Therefore, the presence or absence of surplus power of the solar power generation panel 10 can be determined from the magnitude of the received power Pr. Even when the output of the solar power generation panel 10 is constant and the load L fluctuates, it can be determined by the same method.

[0064] When the received power Pr is greater than the first determination value PX, it is determined that there is no surplus power (S120: NO). When the received power Pr is less than or equal to the first determination value PX, it is determined that there is surplus power (S120: YES).

[0065] When it is determined that there is surplus power, the process proceeds to S130 and charging is started. That is, the control device 50 starts a charging operation to charge the surplus power of the solar power generation panel 10 into the storage battery 15 by controlling the second converter circuit 23.

[0066] After starting charging, the process proceeds to S140, and the control device 50 controls the charging power Pc to the storage battery 15 by controlling the second converter circuit 23 so that the received power Pr becomes the second target value P2.

[0067] Thereafter, the process proceeds to S150, and the control device 50 determines whether the received power Pr is greater than a second determination value PY. The second determination value PY is a value for determining the stop of charging of surplus power. The second determination value PY is greater than the first determination value PX and the second target value P2.

[0068] When the received power Pr is equal to or less than the second determination value PY (S150: NO), the control device 50 continues to charge the surplus power. Thereby, as long as the state where the received power Pr is lower than the second determination value PY continues, the surplus power of the solar power generation panel 10 can be charged to the power storage device 15.

[0069] On the other hand, when the received power Pr becomes greater than the second determination value PY due to load fluctuations or the like (S150: YES), the control device 50 shifts to S160 and stops charging the surplus power. Then, it returns to S10.

[0070] FIG. 9 is a graph showing the relationship between the power supply and demand of the microgrid S. The load power PL is constant. “P1” and “PX” are 150 [W] as an example, and “P2” is 300 [W] as an example.

[0071] The output PPV of the solar power generation panel 10 increases after time t0. The received power Pr decreases after time t0 and decreases to the first target value P1 at time t1.

[0072] Since “P1” and “PX” are equal at 150 [W], when the received power Pr reaches the first target value P1 of 150 [W] at time t1, the storage battery 15 starts charging the surplus power. The charging power Pc is controlled so that the received power Pr becomes the second target value P2 of 300 [W].

[0073] Therefore, after time t1, the received power Pr is maintained at the second target value P2 of 300 [W]. On the other hand, the first target value P1 of the first control is 150 [W], which is lower than the received power Pr (Pr = 300 [W]). Therefore, the solar power generation panel 10 continuously increases the output PPV without being subject to output limitation.

[0074] The output of the solar power generation panel 10 reaches the upper limit output of the power generation upper limit at time t2, and thereafter maintains the upper limit output. The charging power Pc to the storage battery 15 becomes constant after time t2 when the solar power generation panel 10 reaches the upper limit output.

[0075] 3. Regarding the first target value, the second target value, and the determination value The magnitude relationship among the first target value P1, the second target value P2, and the first determination value PX is as follows. P1 ≤ PX < P2 ····· (2)

[0076] As shown in FIG. 5, after the output of the photovoltaic panel 10 starts, by the first control, the received power Pr is maintained at or above the first target value P1 (Pr ≥ P1).

[0077] When P1 > PX, since the received power Pr does not decrease to the first determination value PX, the charging of the storage battery 15 is not started, and there is a possibility of wasting the surplus power of the photovoltaic panel 10.

[0078] As shown in FIG. 9, by setting the first determination value PX numerically within the fluctuation range of the received power Pr (the range above P1) by the first control with "P1" ≤ "PX", it is possible to suppress the charging start failure and charge the surplus power of the photovoltaic panel 10 to the storage battery 15.

[0079] Since "PX" < "P2", at the charging start time point (Pr = PX), P2 - Pr > 0, and P2 - Pr can be used as the surplus power to charge the storage battery 15.

[0080] Since "P1" < "P2", as shown in FIG. 10, it is possible to create a cycle of repeating the "charging of surplus power" by the storage battery 15 and the "output increase" of the photovoltaic panel 10. Therefore, after the time t1 in FIG. 9, while continuously increasing the output of the photovoltaic panel 10, it is possible to charge the surplus portion to the storage battery 15. That is, the photovoltaic panel 10 can be maintained at a high output, and the surplus power of the photovoltaic panel 10 can be charged, so the energy utilization efficiency is high.

[0081] 4. Effects This technology can suppress the poor start of charging of surplus power and effectively utilize the generated power of the solar power generation panel 10, which is a distributed power source. That is, by charging the surplus power of the solar power generation panel 10 into the storage battery 15 and discharging it when the generated power is insufficient, the received power Pr of the microgrid S can be reduced.

[0082] <Embodiment 2> In Embodiment 1, the magnitude relationship among the first target value P1, the second target value P2, and the first determination value PX was expressed by Equation (2). In Embodiment 2, it is expressed by Equation (3).

[0083] P1, P2 ≦ PX ····· (3) The magnitudes of P1 and P2 may be such that P1 = P2, or P2 > P1.

[0084] FIG. 11 is a graph showing the relationship between the power supply and demand of the microgrid S. The load power PL is constant. "P1" and "P2" are 300 [W] as an example, and "PX" is 300 [W] as an example. That is, P1 = P2 = PX = 300 [W].

[0085] In FIG. 11, at time t0, the solar power generation panel 10 starts to output, and at time t3, the output of the solar power generation panel 10 reaches the power generation upper limit. Compared with FIG. 9, it takes a long time for the output of the solar power generation panel 10 to reach the power generation upper limit, but the surplus power of the solar power generation panel 10 can be charged into the storage battery 15, and the generated power of the solar power generation panel 10 can be effectively utilized.

[0086] The reason why it takes a long time for the output of the solar power generation panel 10 to reach the power generation upper limit is as follows. By executing the second control for charging surplus power, the received power Pr is controlled to the second target value P2 (Pr ≒ P2).

[0087] In the case of Embodiment 2 (P1 = P2), compared with Embodiment 1 (P1 < P2), the difference between P1 and Pr (Pr - P1) becomes smaller, so the increase in the output of the solar power generation panel 10 by the first control is dull, and the time (t1 to t3) from the start of charging to reaching the power generation upper limit becomes longer.

[0088] <Other Embodiments> The present invention is not limited to the embodiments described above and in the drawings. For example, the following embodiments are also included in the technical scope of the present invention.

[0089] (1) A distributed power source is a general term for all small-scale power generation facilities that are distributed adjacent to the demand location. The distributed power source is not limited to the solar power generation panel 10, and may also be a wind power generation or biomass power generation device, etc. When the distributed power source is AC, it may be connected to the first converter circuit 21 via a rectifier. The distributed power source may be a power source using renewable energy or a power source using fossil fuel.

[0090] (2) In Embodiment 1, as an example of the microgrid S, a grid having a linear power line (main line) 5 was shown, but a grid having a circular power line (main line) may also be used.

[0091] (3) This technology can be applied not only to a microgrid (small-scale power system), but also to any grid (power system) that is interconnected with another power system and equipped with a power storage device. In the embodiment, the battery 15 was exemplified as the power storage device, but the power storage device may also be a capacitor or the like.

Description of Reference Numerals

[0092] 1 Power system 2 System power source 3 Power receiving point 10 Solar power generation panel (an example of the "distributed power source" of the present invention) 15 Battery 20 Power conditioner 21 First converter circuit (an example of the "first adjustment unit" of the present invention) 23 Second converter circuit (an example of the "second adjustment unit" of the present invention) 31 Inverter circuit 40 External measuring instrument 50 Control device S Microgrid

Claims

1. A power control device for a grid that includes a distributed power source and a power storage device and is connected to a power system, a first adjustment unit that adjusts the output of the distributed power source, a second adjustment unit that adjusts the charge and discharge of the power storage device, an inverter circuit that converts the power supplied from the distributed power source and the power storage device from DC to AC and outputs it, and a control device, wherein the control device performs a first control to control the output of the distributed power source by the first adjustment unit so that the received power of the grid becomes a first target value, and performs a second control to charge the power storage device with the surplus power of the distributed power source via the second adjustment unit so that the received power of the grid becomes a second target value, wherein the control device starts the second control when the received power from the power system to the grid drops to a first determination value, and the first determination value for starting the second control is equal to or greater than the first target value. A power control device.

2. The power control device according to claim 1, wherein the second target value is greater than the first target value. A power control device.

3. The power control device according to claim 1 or claim 2, wherein the magnitude relationship among the first target value, the second target value, and the first determination value is the first target value ≤ the first determination value < the second target value. A power control device.

4. A grid connected to a power system, including a distributed power source, a power storage device connected in parallel to the distributed power source, the power control device according to any one of claims 1 to 3, and a load. A grid.

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