JP2020184812A - Distributed power system, control device, and control method - Google Patents

Abstract

To provide a technique capable of contributing to the realization of inexpensive distributed power systems suitable for stabilizing the power supply.SOLUTION: A control device 8 calculates differential power Pdelt, which is obtained by subtracting command total generated power Psum* from total generated power Psum of multiple power generation devices 32. When the differential power Pdelta is larger than zero, the control device 8 executes first processing for reducing first generated power P1 before executing second processing in a case of executing the second processing for increasing charge/discharge power Pstorage. When the differential power Pdelta is smaller than zero, the control device 8 executes third processing for increasing the first generated power P1 before executing fourth processing in a case of executing the fourth processing for reducing the charge/discharge power Pstorage.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to distributed power systems, control devices and control methods.

Distributed generation systems are known. Distributed generation systems may include multiple generators. An example of such a distributed power supply system is described in Patent Document 1.

The distributed power supply system 100 described in Patent Document 1 is shown in FIG. The distributed power supply system 100 includes a power generation device 110, a DC bus 104, a power storage device 102, a grid interconnection device 108, and an overall control device 109.

The power generation device 110 uses renewable energy to generate electricity. Specifically, the power generation device 110 is a solar power generation device. The power generation device 110 includes a solar cell 101 and a DC-DC converter 103. The DC-DC converter 103 converts the DC voltage output from the solar cell 101 into a DC voltage having a predetermined magnitude.

The power storage device 102 is connected to the DC-DC converter 103 via the DC bus 104. The electric power generated by the power generation device 110 is supplied to the power storage device 102, and the electric power is charged.

The grid interconnection device 108 has a DC-AC inverter 107. The DC-AC inverter 107 reversely converts the DC power from the power storage device 102 into AC power that can be connected to the power system 105. The power obtained by the inverse conversion is supplied to the load 106 and the power system 105.

The control device 109 receives the predicted data of the amount of power generation. The control device 109 sets a target value of the remaining charge of the power storage device 102 based on the forecast data of the power generation amount and the power consumption forecast. The control device 109 changes the output of the grid interconnection device 108 in a fixed time unit based on the target value and the actual value of the remaining charge.

Japanese Unexamined Patent Publication No. 2012-75224

The present disclosure provides a technique that can contribute to the realization of an inexpensive distributed power supply system suitable for a stable supply of electric power.

This disclosure is
Multiple power generation devices including the first power generation device,
A power storage device connected to the plurality of power generation devices and
A power output device including a power input unit connected to the plurality of power generation devices and the power storage device, and a power output unit connected to a commercial power source.
The first detector and
It is provided with a control device that causes a specific power, which is a value representing the power output from the power output unit and is a value specified by using the first detection device, to follow a constant target power.
The power generated by the first power generation device is defined as the first power generation power, and when it is positive, it refers to the charging power of the power storage device, and when it is negative, the absolute value indicates the discharge power of the power storage device. When defined as the charge / discharge power of the power storage device, the control device is defined as
Calculate the differential power obtained by subtracting the command total power generation power from the total power generation power of the plurality of power generation devices.
When the differential power is larger than zero, when the second process of increasing the charge / discharge power is executed, the first process of reducing the first generated power is executed before the second process is executed. ,
When the differential power is smaller than zero, when the fourth process of reducing the charge / discharge power is executed, the third process of increasing the first generated power is executed before the fourth process is executed. ,
Provides a distributed generation system.

The technology according to the present disclosure can contribute to the realization of an inexpensive distributed power supply system suitable for a stable supply of electric power.

FIG. 1 is a configuration diagram of a distributed power supply system according to an embodiment. FIG. 2A is a configuration diagram of a Rankine cycle power generation power source according to the embodiment. FIG. 2B is a block diagram of the power converter according to the embodiment. FIG. 3 is a block diagram of the photovoltaic power generation device according to the embodiment. FIG. 4 is a block diagram of the power storage device according to the embodiment. FIG. 5 is a control flowchart of the embodiment. FIG. 6A is an explanatory diagram of a change with time of electric power in the embodiment. FIG. 6B is an explanatory diagram of a change over time in electric power in a comparative example. FIG. 6C is an explanatory diagram of a change over time in electric power in a comparative example. FIG. 6D is an explanatory diagram of a change over time in electric power in a comparative example. FIG. 6E is an explanatory diagram of a change over time in electric power in a comparative example. FIG. 7 is a configuration diagram of a conventional distributed power supply system.

(Findings underlying this disclosure)
Power generation devices that use renewable energy such as sunlight are known. The generated power of such a power generation device is liable to fluctuate depending on the natural environment. Patent Document 1 describes that fluctuations in generated power are absorbed by the power storage device.

However, the generated power of a power generation device using renewable energy can fluctuate greatly. Therefore, when the fluctuation of the generated power is absorbed by the power storage device according to Patent Document 1, a large-capacity power storage device is required. However, a large-capacity power storage device is expensive.

Patent Document 1 also describes that a target value of the remaining charge of the power storage device is set based on the predicted data of the amount of power generation. However, the expectations may not be true. If the prediction is wrong, the power storage device may be fully charged or over-discharged. In these conditions, fluctuations in generated power may not be absorbed. Therefore, it is difficult to stably supply electric power to the supply destinations such as the load and the electric power system only by the control based on the forecast data.

For the above reasons, the technology of Patent Document 1 has room for improvement from the viewpoint of realizing an inexpensive distributed power supply system suitable for a stable supply of electric power.

(Summary of one aspect relating to this disclosure)
The distributed power supply system according to the first aspect of the present disclosure is
Multiple power generation devices including the first power generation device,
A power storage device connected to the plurality of power generation devices and
A power output device including a power input unit connected to the plurality of power generation devices and the power storage device, and a power output unit connected to a commercial power source.
The first detector and
It is provided with a control device that causes a specific power, which is a value representing the power output from the power output unit and is a value specified by using the first detection device, to follow a constant target power.
The power generated by the first power generation device is defined as the first power generation power, and when it is positive, it refers to the charging power of the power storage device, and when it is negative, the absolute value indicates the discharge power of the power storage device. When defined as the charge / discharge power of the power storage device, the control device is defined as
Calculate the differential power obtained by subtracting the command total power generation power from the total power generation power of the plurality of power generation devices.
When the differential power is larger than zero, when the second process of increasing the charge / discharge power is executed, the first process of reducing the first generated power is executed before the second process is executed. ,
When the differential power is smaller than zero, when the fourth process of reducing the charge / discharge power is executed, the third process of increasing the first generated power is executed before the fourth process is executed. ..

The technique according to the first aspect can contribute to the realization of an inexpensive distributed power supply system suitable for a stable supply of electric power.

In the second aspect of the present disclosure, for example, in the distributed power supply system according to the first aspect,
The control device may update the command first generated power of the first power generation device at a certain control cycle.
The first generated power may follow the commanded first generated power of the first power generation device.
The control cycle may be 1 millisecond or less.

The second aspect is suitable for controlling the first generated power with high responsiveness.

In the third aspect of the present disclosure, for example, in the distributed power supply system according to the first or second aspect.
The first power generation device may be a thermoelectric power generation device that generates power by using heat, or a fuel cell power generation device.

The power generation device of the third aspect is a specific example of the first power generation device.

In the fourth aspect of the present disclosure, for example, in the distributed power supply system according to any one of the first to third aspects.
The plurality of power generation devices may include a second power generation device.
The second power generation device may be a power generation device that utilizes renewable energy.

The second power generation device of the fourth aspect utilizes renewable energy. Such a second power generation device has a merit that the environmental load is small and a demerit that the generated power can fluctuate depending on the natural environment. However, the second power generation device of the fourth aspect is combined with the technique of the first aspect. As a result, the above-mentioned advantages can be obtained while suppressing the above-mentioned disadvantages.

In the fifth aspect of the present disclosure, for example, in the distributed power supply system according to the fourth aspect,
The second power generation device may be a solar power generation device or a wind power generation device.

The power generation device of the fifth aspect is a specific example of a power generation device using renewable energy.

In the sixth aspect of the present disclosure, for example, in the distributed power supply system according to any one of the first to fifth aspects.
The control device may set a lower limit power which is a lower limit of the command first generated power to be followed by the first generated power and an upper limit power which is an upper limit of the command first generated power.
The second process may be started when the command first generated power reaches the lower limit power by the first process.
The fourth process may be started when the command first generated power reaches the upper limit power by the third process.

According to the sixth aspect, the adjustment of the total generated power by the adjustment of the first generated power can be executed within a reasonable range for the first power generation device.

In the seventh aspect of the present disclosure, for example, in the distributed power supply system according to any one of the first to sixth aspects.
The operation mode executed by the control device includes a first mode in which any one of a plurality of processes including the first process, the second process, the third process, and the fourth process is selected and executed. Well,
The first generated power at the start of the first mode may be greater than zero and less than the rated value of the first generated power.

According to the seventh aspect, after the first mode is started, the state in which the first generated power can be increased or decreased is likely to be continued. This is suitable for suppressing the charging / discharging of the power storage device. According to the operation in which charge / discharge can be easily suppressed, it becomes possible to use an inexpensive power storage device having a suppressed capacity.

The control device according to the eighth aspect of the present disclosure is
Multiple power generation devices including the first power generation device,
A power storage device connected to the plurality of power generation devices and
A power output device including a power input unit connected to the plurality of power generation devices and the power storage device, and a power output unit connected to a commercial power source.
A distributed power supply system including a first detection device has a specific power target, which is a value representing the power output from the power output unit and is a value specified by using the first detection device. It is a control device that controls to follow the electric power.
The power generated by the first power generation device is defined as the first power generation power, and when it is positive, it refers to the charging power of the power storage device, and when it is negative, the absolute value indicates the discharge power of the power storage device. When defined as the charge / discharge power of the power storage device, the control device is defined as
Calculate the differential power obtained by subtracting the command total power generation power from the total power generation power of the plurality of power generation devices.
When the differential power is larger than zero, when the second process of increasing the charge / discharge power is executed, the first process of reducing the first generated power is executed before the second process is executed. ,
When the differential power is smaller than zero, when the fourth process of reducing the charge / discharge power is executed, the third process of increasing the first generated power is executed before the fourth process is executed. ..

The technique according to the eighth aspect can contribute to the realization of an inexpensive distributed power supply system suitable for a stable supply of electric power.

The control method according to the ninth aspect of the present disclosure is
Multiple power generation devices including the first power generation device,
A power storage device connected to the plurality of power generation devices and
A power output device including a power input unit connected to the plurality of power generation devices and the power storage device, and a power output unit connected to a commercial power source.
A distributed power supply system including a first detection device is provided with a specific power target, which is a value representing the power output from the power output unit and is a value specified by using the first detection device. It is a control method that controls to follow the electric power.
The power generated by the first power generation device is defined as the first power generation power, and when it is positive, it refers to the charging power of the power storage device, and when it is negative, the absolute value indicates the discharge power of the power storage device. When defined as the charge / discharge power of a power storage device,
To calculate the differential power obtained by subtracting the command total power generation power from the total power generation power of the plurality of power generation devices.
When the differential power is larger than zero, when the second process of increasing the charge / discharge power is executed, the first process of reducing the first generated power is executed before the second process is executed. That and
When the differential power is smaller than zero, when the fourth process of reducing the charge / discharge power is executed, the third process of increasing the first generated power is executed before the fourth process is executed. That and
including.

The technique according to the ninth aspect can contribute to the realization of an inexpensive distributed power supply system suitable for a stable supply of electric power.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present invention is not limited to the following embodiments.

(Embodiment 1)
FIG. 1 shows the distributed power supply system 1 according to the first embodiment.

The distributed power supply system 1 shown in FIG. 1 includes a plurality of power generation devices 32, a first detection device 7, a second detection device 4, a power output device 6, a control device 8, and a power storage device 9. ing.

The plurality of power generation devices 32, the power storage device 9, and the power output device 6 are connected to each other. Specifically, this connection is made via the DC electric circuit 35.

The distributed generation system 1 may be connected to a commercial power source 5A and a load 5B. Specifically, the power output device 6, the commercial power source 5A, and the load 5B can be connected to each other. More specifically, this connection may be made via an alternating current line 36.

The electric power generated by the plurality of power generation devices 32 can be supplied to the power storage device 9. The electric power generated by the plurality of power generation devices 32 and the electric power stored in the power storage device 9 can be supplied to the load 5B via the power output device 6. Power can also be supplied to the load 5B from the commercial power source 5A.

In one example, power is supplied from the distributed power supply system 1 to the load 5B. If this power supply cannot meet the required power of the load 5B, the shortage of power is supplied from the commercial power source 5A to the load 5B. Power does not reverse power from the distributed power system 1 to the commercial power supply 5A.

In another example, power can be reverse power flow from the distributed power system 1 to the commercial power supply 5A.

The load 5B is not particularly limited. In one example, the load 5B is a factory electrical installation. In another example, the load 5B is a household appliance.

Hereinafter, the components of the distributed power supply system 1 will be described.

The plurality of power generation devices 32 include a first power generation device 3 and a second power generation device 2. In the present embodiment, the plurality of power generation devices 32 are two power generation devices, the first power generation device 3 and the second power generation device 2. However, the plurality of power generation devices 32 may further include other power generation devices.

The first power generation device 3 is connected to the DC electric circuit 35. The first power generation device 3 has a power generation adjusting power. Having a power generation adjusting power means that it can increase or decrease by controlling its own power generation. In the present embodiment, the generated power of the first power generation device 3 can be sequentially increased or decreased by the control by the control device 8.

In the example of FIG. 1, the first power generation device 3 includes a power generation power source 3R and a power converter 3H.

The power generation power source 3R generates power. The power generation power source 3R has a power generation adjustment power. In the present embodiment, the generated power of the power generation power source 3R can be sequentially increased or decreased by the control by the control device 8.

Hereinafter, the generated power of the first power generation device 3 may be referred to as the first generated power P ₁ . Specifically, the first generated power P ₁ is DC power. The first generated power P ₁ is output to the DC electric circuit 35. In the example of FIG. 1, the first generated power P ₁ is the output power of the power converter 3H.

In the present embodiment, the first power generation device 3 is a thermoelectric power generation device that uses heat to generate power. Specifically, the first power generation device 3 is a waste heat power generation device that generates power by utilizing waste heat. Further, in the present embodiment, the first power generation device 3 is a Rankine cycle power generation device.

In the present embodiment, the power generation power source 3R is a power generation power source that uses heat to generate power. Specifically, the power generation power source 3R is a power generation power source that generates power by using exhaust heat. Further, in the present embodiment, the power generation power source 3R is a Rankine cycle power generation power source.

In the above description of the power generation device and the power generation power source that generate power using the exhaust heat, an example of the exhaust heat supply source is a factory. A specific example of a source of exhaust heat is a furnace. This furnace is, for example, a furnace used for the production of castings.

In the present embodiment, the power converter 3H is an AC-DC converter.

Hereinafter, the first power generation device 3 which is a thermoelectric power generation device may be referred to as a thermoelectric power generation device 3. The first power generation device 3 which is a waste heat power generation device may be referred to as a waste heat power generation device 3. The first power generation device 3 which is a Rankine cycle power generation device may be referred to as a Rankine cycle power generation device 3. The power generation power source 3R, which is the Rankine cycle power generation power source, may be referred to as the Rankine cycle power generation power source 3R. The power converter 3H, which is an AC-DC converter, may be referred to as an AC-DC converter 3H.

In another example, the first power generation device 3 is a fuel cell power generation device. The power generation power source 3R is a fuel cell. The power converter 3H is a DC-DC converter.

As understood from the above description, in this embodiment, the Rankine cycle power generation device 3 includes a Rankine cycle power generation power source 3R and an AC-DC converter 3H.

FIG. 2A shows the Rankine cycle power generation power source 3R of this embodiment. The Rankine cycle power generation power source 3R of the present embodiment includes a pump 3A, an evaporator 3B, a temperature sensor 3D, an expander 3C, a bypass valve 3E, a condenser 3F, and a generator 3G.

In the Rankine cycle power generation power source 3R, a circulation path for the refrigerant is formed. In this circulation path, the pump 3A, the evaporator 3B, the expander 3C, and the condenser 3F appear in this order.

The pump 3A circulates the refrigerant by pumping the refrigerant. The evaporator 3B recovers heat from the heating medium and heats the refrigerant with the heat. The expander 3C expands the refrigerant. The condenser 3F condenses the refrigerant by removing the heat of the refrigerant. The heat taken away by the condenser 3F is given to the cooling medium.

In this embodiment, the heating medium is a gas. Specifically, the heating medium is exhaust gas. That is, the Rankine cycle power generation power source 3R is a power generation power source using exhaust heat. The source of the exhaust gas is, for example, a factory, and in one specific example, a furnace, which may be a furnace used for manufacturing castings. The evaporator 3B is, for example, a fin and tube heat exchanger.

In the present embodiment, the refrigerant becomes a high-pressure gas by heating in the evaporator 3B. The expander 3C expands the refrigerant that has become a high-pressure gas.

In this embodiment, the cooling medium is a gas. Specifically, the cooling medium is air in the atmosphere. However, the cooling medium may be a liquid such as water. The condenser 3F may include a fan. The condenser 3F is, for example, a fin-and-tube heat exchanger, a plate heat exchanger, or a double-tube heat exchanger.

In the Rankine cycle power generation power source 3R, a refrigerant bypass path is formed. The bypass path bypasses the expander 3C. Specifically, the bypass path is a portion downstream of the evaporator 3B and upstream of the expander 3C in the circulation path, and a portion downstream of the expander 3C and upstream of the condenser 3F in the circulation path. The part is connected.

The bypass valve 3E is provided in the bypass path. By setting the opening degree of the bypass valve 3E to non-zero, a part or all of the refrigerant flowing through the circulation path can flow into the bypass valve 3E.

The bypass valve 3E may be a flow rate adjusting valve or an on-off valve. Here, the flow rate adjusting valve is a valve capable of taking an opening degree larger than 0% and smaller than 100%. The on-off valve is a valve whose opening degree is set to either 0% or 100%.

The temperature sensor 3D is provided in a portion of the circulation path on the downstream side of the evaporator 3B and on the upstream side of the expander 3C. The temperature sensor 3D detects the temperature of the refrigerant in this portion. The temperature sensor 3D can be used to control the components of the Rankine cycle power generator 3. Specifically, the temperature sensor 3D is provided at a portion upstream of the branch point to the bypass path in the circulation path. The detection temperature of the temperature sensor 3D can be substantially the inlet temperature of the expander 3C.

The generator 3G is connected to the expander 3C. In the expander 3C, rotational energy is generated by expansion. In the generator 3G, the rotor is rotated by the rotational energy. In this way, AC power is generated in the generator 3G.

The AC-DC converter 3H is connected to the generator 3G. AC power generated by the generator 3G is supplied to the AC-DC converter 3H. The AC-DC converter 3H converts this AC power into DC power.

The configuration of the AC-DC converter 3H of this embodiment is shown in FIG. 2B. The AC-DC converter 3H of the present embodiment includes switching elements 16 to 21, diodes 51 to 56, and a capacitor 22. The capacitor 22 is an output capacitor.

In the AC-DC converter 3H, a first-phase circuit 61, a second-phase circuit 62, and a third-phase circuit 63 are configured. The first-phase circuit 61, the second-phase circuit 62, and the third-phase circuit 63 constitute a switching circuit 60. The first-phase circuit 61, the second-phase circuit 62, the third-phase circuit 63, and the capacitor 22 are connected in parallel with each other. The first-phase circuit 61, the second-phase circuit 62, and the third-phase circuit 63 are each connected to the generator 3G.

In the present embodiment, the first phase circuit 61, the second phase circuit 62, and the third phase circuit 63 are connected to the first phase, the second phase, and the third phase of the generator 3G, respectively. In the present embodiment, the first phase, the second phase and the third phase are the U phase, the V phase and the W phase, respectively.

The first phase circuit 61 includes switching elements 16 and 17, and diodes 51 and 52. The switching elements 16 and 17 are connected in series via a first connection point 66. The switching element 16 and the diode 51 are connected in parallel. The switching element 17 and the diode 52 are connected in parallel.

The second phase circuit 62 includes switching elements 18 and 19 and diodes 53 and 54. The switching elements 18 and 19 are connected in series via a second connection point 67. The switching element 18 and the diode 53 are connected in parallel. The switching element 19 and the diode 54 are connected in parallel.

The third phase circuit 63 includes switching elements 20 and 21 and diodes 55 and 56. The switching elements 20 and 21 are connected in series via a third connection point 68. The switching element 20 and the diode 55 are connected in parallel. The switching element 21 and the diode 56 are connected in parallel.

In the present embodiment, the first connection point 66 is connected to the first phase of the generator 3G. The second connection point 67 is connected to the second phase of the generator 3G. The third connection point 68 is connected to the third phase of the generator 3G.

The rotation speed of the generator 3G is controlled by using the AC-DC converter 3H. More specifically, the switching of the switching elements 16 to 21 is controlled so that the AC-DC converter 3H applies the regenerative brake to the generator 3G to obtain the regenerative power. The control using the AC-DC converter 3H is performed by the control device 8. The capacitor 22 absorbs the instantaneous pulsation of the regenerative power.

In one specific example, the switching elements 16 to 21 are driven by pulse width modulation (PWM). More specifically, the PWM signal is supplied to the switching elements 16 to 21. Then, the switching elements 16 to 21 switch based on the PWM signal.

In the example of FIG. 2B, the switching elements 16 to 21 are, for example, an insulated gate bipolar transistor (IGBT). However, the switching elements 16 to 21 may be other switching elements such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistor).

As understood from the above description, in the present embodiment, the first power generation device 3 includes a generator 3G that generates power by rotating a rotor, and a power converter 3H including a switching circuit 60. The control device 8 controls the first generated power P ₁ by controlling the rotation of the rotor using the switching circuit 60. This embodiment is suitable for controlling the first generated power P ₁ with high responsiveness.

Specifically, the control of the first generated power P ₁ can be executed by controlling the rotation speed of the generator 3G using the AC-DC converter 3H. This control may be performed by the control device 8.

By controlling the rotational speed of the pump 3A, to control the flow rate of refrigerant flowing through the circulation path of the above configuration for controlling the first power generating power P ₁ may also be employed. By controlling the opening degree of the bypass valve 3E, to control the flow rate of the refrigerant flowing in the circulation path, configured to control the first power generating power P ₁ may also be employed. Further, a configuration is also adopted in which a brake circuit is provided in the first power generation device 3 and the first power generation power P ₁ is controlled by consuming a part of the DC power obtained by the first power generation device 3 in the brake circuit. obtain. These controls may also be performed by the control device 8. The first power generation is performed by combining two or more selected from the above rotor rotation speed (specifically, rotation speed) control, pump 3A rotation speed control, bypass valve 3E opening control, and power consumption by the brake circuit. A configuration that controls the power P ₁ can also be adopted.

The configuration of the AC-DC converter 3H shown in FIG. 2B can be adopted even when the power generation power source 3R is not the Rankine cycle power generation power source.

As can be understood from the above description, control of rotor rotation using a switching circuit can be adopted when the first power generation device is a Rankine cycle power generation device. In addition, this control may be adopted when the first power generation device has a rotor and the first power generation device is another type of power generation device. Of course, this control is adopted regardless of whether the first power generation device is a Rankine cycle power generation device or not when the first power generation device is a heat power generation device such as a waste heat power generation device and has a rotor. Can be done.

The number of power generation sources included in the first power generation device 3 is not limited to one. This number may be plural. In this case, the first power generation device 3 includes the same number of power converters as the number of power generation power sources, and a plurality of power generation power sources and a plurality of power converters can be connected one-to-one. In this case, the power generation power source and the power converter can be the elements exemplified as the power generation power source 3R and the power converter 3H. The plurality of power sources may be different types of power sources, such that one power source is a Rankine cycle power source and another is a fuel cell. Further, the plurality of power generation power sources may be the same type of power generation power sources, such that one power generation power source and another power generation power source are Rankine cycle power generation power sources. This point is the same for a plurality of power converters. Further, in this case, the electric power output by the first power generation device 3 by the power generation of a plurality of power generation power sources is referred to as the first power generation power P ₁ .

Returning to FIG. 1, the second power generation device 2 is connected to the DC electric circuit 35. During the operation of the second power generation device 2, the generated power of the second power generation device 2 may fluctuate depending on the weather and the like. Specifically, the second power generation device 2 is a power generation device that uses renewable energy.

In the example of FIG. 1, the second power generation device 2 includes a power generation power source 2A and a power converter 2B.

In the present embodiment, the second power generation device 2 is a solar power generation device. Specifically, the power generation power source 2A is a solar cell. The power converter 2B is a DC-DC converter.

Hereinafter, the second power generation device 2 which is a solar power generation device may be referred to as a solar power generation device 2. The power generation power source 2A, which is a solar cell, may be referred to as a solar cell 2A. The power converter 2B, which is a DC-DC converter, may be referred to as a DC-DC converter 2B.

In another example, the second power generation device 2 is a wind power generation device. Specifically, the power generation power source 2A is a wind turbine. The power converter 2B is a power converter that combines an AC-DC converter and a DC-DC converter.

FIG. 3 shows a specific example of the second power generation device 2 according to the present embodiment. In this specific example, the DC-DC converter 2B is a DC chopper circuit. Hereinafter, the DC-DC converter 2B, which is a DC chopper circuit, may be referred to as a DC chopper circuit 2B.

In the specific example shown in FIG. 3, the DC chopper circuit 2B includes capacitors 41 and 42, a switching element 13, a diode 57, a rectifier diode 14, and a reactor 15. The capacitor 41 is an input capacitor. The capacitor 42 is an output capacitor.

The switching element 13 and the diode 57 are connected in parallel.

The solar cell 2A, the reactor 15, and the switching element 13 are connected in this order. Current can flow through the solar cell 2A, the reactor 15, and the switching element 13 in this order.

Further, the solar cell 2A, the reactor 15, the rectifier diode 14, and the DC electric circuit 35 are connected in this order. Current can flow in this order through the solar cell 2A, the reactor 15, the rectifier diode 14, and the DC electric circuit 35.

Specifically, a DC voltage is input from the solar cell 2A to the DC chopper circuit 2B. The switching of the switching element 13 is controlled. When the switching element 13 is on, a current flows from the solar cell 2A to the reactor 15 and the switching element 13 in this order, and energy is stored in the reactor 15. When the switching element 13 is off, a current flows from the solar cell 2A to the reactor 15 and the diode 14 in this order, and the energy stored in the reactor 15 is output via the diode 14. By such an operation, the DC chopper circuit 2B boosts the DC voltage input from the solar cell 2A and conducts a current to the diode 14 to transfer power to the DC electric circuit 35. The control using the DC chopper circuit 2B is performed by the control device 8.

In one specific example, the switching element 13 is driven by pulse width modulation. More specifically, the PWM signal is supplied to the switching element 13. Then, the switching element 13 switches based on the PWM signal.

In one specific example, MPPT (Maximum Power Point Tracking) control of the solar cell 2A is executed. More specifically, the output current of the solar cell 2A is controlled by using the DC chopper circuit 2B so that the generated power of the solar cell 2A is maximized.

In the example of FIG. 3, the switching element 13 is a MOSFET. However, the switching element 13 may be another switching element such as an IGBT.

The configuration of the DC chopper circuit 2B shown in FIG. 3 can be adopted even when the power generation power source 2A is not a solar cell.

Hereinafter, the generated power of the second power generation device 2 may be referred to as the second generated power P ₂ . Specifically, the second generated power P ₂ is DC power. The generated power P ₂ is output to the DC electric circuit 35. In the example of FIG. 1, the generated power P ₂ is the output power of the power converter 2B.

The number of power generation sources included in the second power generation device 2 is not limited to one. This number may be plural. In this case, the second power generation device 2 includes the same number of power converters as the number of power generation power sources, and a plurality of power generation power sources and a plurality of power converters can be connected one-to-one. In this case, the power generation power source and the power converter can be the elements exemplified as the power generation power source 2A and the power converter 2B. The plurality of power generation power sources may be different types of power generation power sources. Further, the plurality of power generation power sources may be the same type of power generation power sources. This point is the same for a plurality of power converters. Further, in this case, the electric power output by the second power generation device 2 by the power generation of a plurality of power generation power sources is referred to as the second power generation power P ₂ .

Returning to FIG. 1, the power storage device 9 is connected to a plurality of power generation devices 32. The electric power generated by the plurality of power generation devices 32 can be supplied to the power storage device 9. Specifically, the power storage device 9 is connected to a plurality of power generation devices 32 via a DC electric circuit 35. The power storage device 9 can function as a power buffer when there is an excess or deficiency in the generated power of the plurality of power generation devices 32.

In the present embodiment, the power storage device 9 is connected to the first power generation device 3 and the second power generation device 2. Therefore, the electric power generated by the first power generation device 3 and the second power generation device 2 can be supplied to the power storage device 9. Specifically, the power storage device 9 is connected to the first power generation device 3 and the second power generation device 2 via the DC electric circuit 35.

In the example of FIG. 1, the power storage device 9 includes a power storage device 9A and a power converter 9B.

In the present embodiment, the power storage device 9A is a storage battery. In the following, the power storage battery 9A, which is a storage battery, may be referred to as a storage battery 9A. Specific examples of the storage battery constituting the power storage device 9A are a lithium ion battery, a nickel hydrogen battery, a lead storage battery, and the like.

Another example of the power storage device 9A is a capacitor. A specific example of the capacitor constituting the power storage device 9A is an electric double layer capacitor.

In the present embodiment, the power converter 9B is a DC-DC converter. Specifically, the power converter 9B is a bidirectional DC-DC converter. More specifically, the power converter 9B is a bidirectional chopper circuit. In the following, the power converter 9B which is a bidirectional DC chopper circuit may be referred to as a bidirectional DC chopper circuit 9B.

Here, the bidirectional DC-DC converter converts the DC voltage input from the first terminal into a DC voltage having a different magnitude and outputs the DC voltage to the second terminal, and inputs the DC voltage from the second terminal. It refers to a converter that can convert DC voltage of different magnitudes and output it to its first terminal, and can execute both.

Similarly, the bidirectional chopper circuit converts the DC voltage input from the first terminal into a DC voltage of a different magnitude and outputs it to the second terminal, and the DC voltage input from the second terminal. Refers to a chopper circuit that can execute both the conversion of DC voltages of different magnitudes and the output to the first terminal.

FIG. 4 shows a specific example of the power storage device 9 according to the present embodiment.

In the specific example shown in FIG. 4, the bidirectional chopper circuit 9B includes switching elements 10 and 11, diodes 58 and 59, a reactor 12, and capacitors 46 and 47. Capacitors 46 and 47 are input / output capacitors.

The switching element 10 and the diode 58 are connected in parallel. The switching element 11 and the diode 59 are connected in parallel.

The DC electric circuit 35, the switching element 10, the reactor 12, and the storage battery 9A are connected in this order. A current can flow in the DC electric circuit 35, the switching element 10, the reactor 12, and the storage battery 9A in this order.

The diode 59, the reactor 12, and the storage battery 9A are connected in this order. Current can flow through the diode 59, the reactor 12, and the storage battery 9A in this order.

The storage battery 9A, the reactor 12, and the switching element 11 are connected in this order. Current can flow through the storage battery 9A, the reactor 12, and the switching element 11 in this order.

The storage battery 9A, the reactor 12, the diode 58, and the DC electric circuit 35 are connected in this order. Current can flow in the storage battery 9A, the reactor 12, the diode 58, and the DC electric circuit 35 in this order.

When charging the storage battery 9A, the switching element 11 is maintained in the off state. The switching of the switching element 10 is controlled. When the switching element 10 is on, current flows through the switching element 10, the reactor 12, and the storage battery 9A in this order. When the switching element 10 is off, the reactor 12 tries to maintain the current flowing through itself, and the current flows through the diode 59, the reactor 12, and the storage battery 9A in this order. By such an operation, the bidirectional chopper circuit 9B functions as a step-down chopper. That is, the bidirectional chopper circuit 9B charges the storage battery 9A by stepping down the DC voltage input from the DC electric circuit 35 and controlling the current of the reactor 12 with the stepped-down voltage.

When discharging from the storage battery 9A, the switching element 10 is maintained in the off state. The switching of the switching element 11 is controlled. When the switching element 11 is on, a current flows from the storage battery 9A to the reactor 12 and the switching element 11 in this order, and energy is stored in the reactor 12. When the switching element 11 is off, a current flows from the storage battery 9A to the reactor 12 and the diode 58 in this order, and the energy stored in the reactor 12 is output via the diode 58. By such an operation, the bidirectional chopper circuit 9B functions as a boost chopper. That is, the bidirectional chopper circuit 9B boosts the DC voltage input from the storage battery 9A and energizes the diode 58 to carry the power to the DC electric circuit 35.

The control using the bidirectional chopper circuit 9B is performed by the control device 8.

In one specific example, the switching element 10 is driven by pulse width modulation. More specifically, the PWM signal is supplied to the switching element 10. Then, the switching element 10 switches based on the PWM signal. The same applies to the switching element 11.

When discharging from the storage battery 9A, synchronous rectification may be performed using the two switching elements 10 and 11. In synchronous rectification, when one of the switching elements 10 and 11 is in the on state, the other is in the off state, and when one is in the off state, the other is in the on state. In synchronous rectification, the two switching elements are turned on and off in a complementary manner in this way, so that conduction loss can be suppressed as compared with diode rectification using a diode. Specifically, synchronous rectification can be realized by turning on the switching element 10 during the period in which the current flows through the diode 58 in the above description.

In the DC chopper circuit 2B shown in FIG. 3, the diode 14 may be changed to the switching element X, and synchronous rectification may be performed using the switching element X and the switching element 13. Specifically, synchronous rectification can be realized by turning on the switching element X during the period in which the current flows through the diode 14 in the above description.

In the example of FIG. 4, the switching elements 10 and 11 are, for example, MOSFETs. However, the switching elements 10 and 11 may be other switching elements such as IGBTs.

The configuration of the bidirectional chopper circuit 9B shown in FIG. 4 can be adopted even when the power storage device 9A is not a storage battery.

In the following, the charge / discharge power of the power storage device 9 may be referred to as P _storage . Here, the positive charge / discharge power refers to the charge power, and the absolute value of the negative charge / discharge power refers to the discharge power. Specifically, the charge / discharge power P _storage is DC power. The charge / discharge power P _storage is input / output to / from the DC electric circuit 35. In the example of FIG. 1, the charge / discharge power P _storage is the input / output power of the bidirectional chopper circuit 9B.

The number of power storage devices included in the power storage device 9 is not limited to one. This number may be plural. In this case, the power storage device 9 includes the same number of power converters as the number of power storage devices, and the plurality of power storage devices and the plurality of power converters can be connected one-to-one. In this case, the power storage device and the power converter can be the elements exemplified as the power storage device 9A and the power converter 9B. The plurality of power storage devices may be different types of power storage devices. Further, the plurality of power storage devices may be the same type of power storage devices. This point is the same for a plurality of power converters. Further, in this case, the electric power charged / discharged by the second power generation device 2 by charging / discharging of a plurality of power storage devices is referred to as charge / discharge electric power P _storage .

Returning to FIG. 1, the second detection device 4 detects the total generated power of the plurality of power generation devices 32. In the following, the total power generated by the plurality of power generation devices 32 may be referred to as the total power generation P _sum . It can be said that the second detection device 4 detects the total generated power P _sum . In this embodiment, the total generated power P _sum is the sum of the generated power P ₂ of the generated power P ₁ and the second power generating apparatus 2 of the first power generating unit 3.

The power output device 6 includes a power input unit 6i and a power output unit 6о.

The power input unit 6i is connected to a plurality of power generation devices 32 and power storage devices 9. Specifically, the power input unit 6i is connected to a plurality of power generation devices 32 and power storage devices 9 via a DC electric circuit 35.

As shown in FIG. 1, the load 5B is connected to the branch portion BP. The power output unit 6о is connected to the commercial power supply 5A via the branch unit BP. Specifically, the power output unit 6о is connected to the commercial power supply 5A and the load 5B via the AC electric circuit 36.

DC power is input to the power input unit 6i from the plurality of power generation devices 32 and the power storage device 9. AC power is output from the power output unit 6о. The electric power is DC-AC converted between the electric power input unit 6i and the electric power output unit 6о.

Specifically, the power input unit 6i is input with power obtained by subtracting the charge / discharge power P _storage of the power storage device 9 from the total generated power P _sum . That is, at the time of charging the power storage device 9, the power input unit 6i is input with the power obtained by subtracting the charging power of the power storage device 9 from the total generated power P _sum . When the power storage device 9 is discharged, the power input unit 6i is input with the total power generated by P _sum and the discharge power of the power storage device 9. As described above, the total generated power P _sum is the total of the generated power of the plurality of power generation devices 32.

In another example, the power is DC-DC converted between the power input unit 6i and the power output unit 6о, and then DC-AC converted.

The distributed power supply system 1 is configured so that a specific power P _out can be specified. Here, the specific power P _out is a value representing the power output from the power output unit 6о. Further, the specific power P _out is a value specified by using the first detection device 7. In this embodiment, the AC electric circuit 36 extends from the power output unit 6о to the commercial power source 5A. A specific electric power P _out can be obtained from the AC electric circuit 36. Specifically, the AC electric circuit 36 includes a first portion 36a and a second portion 36b. The first portion 36a is a portion between the power output unit 6о and the branch unit BP. The second portion 36b is a portion between the branch portion BP and the commercial power supply 5A. The branch electric circuit 37 extends from the branch portion BP to the load 5B. The specific power P _out is obtained from the first portion 36a. In the present embodiment, the specific power P _out represents the active power output from the power output unit 6о.

As described above, in the example of FIG. 1, the specific power P _out is specified by using the first detection device 7. The first detection device 7 includes a current detector 7A, a voltage detector 7B, and a power calculation unit 7C. The current detector 7A and the voltage detector 7B are provided in the AC electric circuit 36. Specifically, the current detector 7A and the voltage detector 7B are provided in the first portion 36a.

The current detector 7A detects an alternating current flowing through a position where the current detector 7A is provided. In the present embodiment, the current detector 7A detects the alternating current output from the power output device 6.

The voltage detector 7B detects the AC voltage applied to the position where it is provided. In the present embodiment, the AC voltage output from the power output device 6 is detected.

The voltage detector 7B may be provided in the second portion 36b. Further, the voltage detector 7B may be provided in the branch electric circuit 37.

The power calculation unit 7C calculates the specific power P _out using the detection current of the current detector 7A and the detection voltage of the voltage detector 7B. As understood from the above description, in the present embodiment, the specific power P _out represents the active power output from the power output device 6.

The control device 8 causes the specific power P _out to follow a _constant target power P _constant ^* . The control device 8 is configured to be able to control the first generated power P ₁ of the first power generation device 3 and the charge / discharge power P _storage of the power storage device 9. In the present embodiment, the control device 8 is configured to be able to control the generated power P ₂ of the second power generation device 2.

Hereinafter, an example of control of the generated power P ₁ of the first power generation device 3 and the charge / discharge power P _storage of the power storage device 9 by the control device 8 will be described with reference to the flowchart of FIG.

In the following description, the command value to the first generated power P ₁ to follow, may be referred to as instruction first generated power P ₁ ^*. The command value that the charge / discharge power P _{storage of the} power storage device 9 should follow may be referred to as the command charge / discharge power P _storage ^* . A command value to the total generated power P _sum to follow, may be referred to as command total generated power P _sum ^*.

Further, in the following description, the expression that electric power is input to the control device 8 may be used. This expression means that information representing the electric power is input to the control device 8.

In the example according to this description, the control device 8 sets the command first generated power P ₁ ^* to a value in the range of the lower limit power P _min or more and the upper limit power P _max or less. The lower limit power P _min and the upper limit power P _max can be set based on the capacity of the first power generation device 3, the operating environment, and the like.

From "start" to "end" in the flowchart of FIG. 5, one control cycle constitutes one. The control device 8 may repeatedly execute this control cycle.

In step S1, the total generated power P _sum is input to the control device 8. Specifically, the total generated power P _sum is input from the second detection device 4 to the control device 8.

After step S1, in step S2, the command total generated power P _sum ^* is input to the control device 8. Specifically, the command total generated power P _sum ^* is input from the _host control device to the control device 8.

After step S2, in step S3, the control device 8 calculates the differential power P _delta . Differential power P _delta is the difference obtained by subtracting the instruction total generated power P _sum ^* from the total generated power P _sum.

After step S3, in step S4, the control device 8 determines which of the first condition, the second condition, the third condition, the fourth condition, and the fifth condition is satisfied.

The first condition is that the differential power P _delta is zero. When the first condition is satisfied, in step S5, the control device 8 maintains the command first generated power P ₁ ^* at the current value. Using the mathematical formula, P ₁ ^* set in step S5 is given by P ₁ ^* (s) = P ₁ ^* (s-1).

Here, P ₁ ^* (s-1) refers to P ₁ ^* before being updated in the current control cycle. P ₁ ^* (s) refers to P ₁ ^* after being updated in this control cycle. The same applies to P _storage ^* .

Further, when the first condition is satisfied, in step S6, the control device 8 sets the command charge / discharge power P _storage ^* to zero. Using the mathematical formula, the P _storage ^* set in step S6 is given by P _storage ^* (s) = P _delta = 0.

The second condition is that the differential power P _delta is larger than zero and the command first generated power P ₁ ^* is larger than the lower limit power P _min . If the second condition is satisfied, in step S7, the control unit 8, the instruction first generated power P ₁ ^*, to minimize the first step size P _WIDTH1. Using the mathematical formula, P ₁ ^* set in step S7 is given by P ₁ ^* (s) = P ₁ ^* (s-1) −P _width 1.

If the second condition is satisfied, in step S8, the control device 8 maintains the command charge / discharge power P _storage ^* at the current value. Using the mathematical formula, the P _storage ^* set in step S8 is given by P _storage ^* (s) = P _storage ^* (s-1).

The third condition is that the differential power P _delta is smaller than zero and the command first generated power P ₁ ^* is smaller than the upper limit power P _max . When the third condition is satisfied, in step S9, the control unit 8, the instruction first generated power P ₁ ^*, is increased by a first step size P _WIDTH1. Using a mathematical formula, P ₁ ^* set in step S9 is given by P ₁ ^* (s) = P ₁ ^* (s-1) + P _width 1.

Further, when the third condition is satisfied, in step S10, the control device 8 maintains the command charge / discharge power P _storage ^* at the current value. Using the mathematical formula, the P _storage ^* set in step S10 is given by P _storage ^* (s) = P _storage ^* (s-1).

The fourth condition is that the differential power P _delta is larger than zero and the command first generated power P ₁ ^* is the lower limit power P _min . When the fourth condition is satisfied, in step S11, the control device 8 maintains the command first generated power P ₁ ^* at the lower limit power P _min . Using the mathematical formula, P ₁ ^* set in step S11 is given by P ₁ ^* (s) = P _min .

Also, when the fourth condition is satisfied, in step S12, the control unit 8, the command discharge power P _storage ^*, is increased by a second step size P _Width2. Using the mathematical formula, the P _storage ^* set in step S12 is given by P _storage ^* (s) = P _storage ^* (s-1) + P _width2 .

The fifth condition is that the differential power P _delta is smaller than zero and the command first generated power P ₁ ^* is the upper limit power P _max . When the fifth condition is satisfied, in step S13, the control device 8 maintains the command first generated power P ₁ ^* at the upper limit power P _max . Using the mathematical formula, P ₁ ^* set in step S13 is given by P ₁ ^* (s) = P _max .

Also, if the fifth condition is satisfied, in step S14, the control unit 8, the command discharge power P _storage ^*, to minimize second step size P _Width2. Using the mathematical formula, the P _storage ^* set in step S14 is given by P _storage ^* (s) = P _storage ^* (s-1) −P _width2 .

After steps S5 and S6, after steps S7 and S8, after steps S9 and S10, after steps S11 and S12, or after steps S13 and S14, steps S15 and S16 are performed. In step S15, the control device 8 transmits the command first generated power P ₁ ^* to the first power generation device 3. In step S16, the control device 8 transmits the command charge / discharge power P _storage ^* to the power storage device 9.

By repeating the control cycle of FIG. 5, the command first generated power P ₁ ^* and the command charge / discharge power P _storage ^* can be sequentially updated. The first generated power P ₁ of the first power generation device 3 follows the command first generated power P ₁ ^* . The charge / discharge power P _storage of the power storage device 9 follows the command charge / discharge power P _storage ^* . In this way, the first power generation device 3 and the power storage device 9 are controlled by the control device 8.

In this embodiment, the control cycle is repeated at the control cycle T _p . Specifically, the control cycle includes updating the command first generated power P ₁ ^{* in} the control device 8, transmitting the command first generated power P ₁ ^* from the control device 8 to the first power generation device 3, and controlling the control device. including a command discharge power P _storage ^* update at 8, and a transmission command discharge power P _storage ^* from the control unit 8 to the power storage device 9. Then, the update of the command first generated power P ₁ ^* in the control device 8 is repeated in the control cycle T _p . The transmission of the command first generated power P ₁ ^* from the control device 8 to the first power generation device 3 is repeated in the control cycle T _p . Update command discharge power P _storage ^* in the control unit 8 is repeated in the control period T _p. Directive discharge power P _storage ^* transmission from the control unit 8 to the power storage device 9 is repeated in the control period T _p.

As can be understood from the above description, in the present embodiment, the control device 8 updates the command first generated power P ₁ ^* possessed by the first power generation device 3 at a certain control cycle T _p . The first generated power P ₁ follows the command first generated power P ₁ ^* possessed by the first power generation device 3. The control period T _p is, for example, 1 millisecond or less, and in one specific example, it is 100 microseconds or less. This is suitable for controlling the first generated power P ₁ with high responsiveness. Specifically, by doing so, even if the generated power of a power generation device other than the first power generation device 3 such as the second generated power P ₂ fluctuates instantaneously, the fluctuation can be caused. On the other hand, the first generated power P ₁ can be controlled with high responsiveness, and the total generated power P _sum can be stabilized. This is advantageous from the viewpoint of maintaining a good power supply-demand balance. More specifically, by doing so, it is possible to control the first generated power P ₁ on the order of 10 milliseconds or milliseconds. The control period T _p is, for example, 100 nanoseconds or more, and may be 1 microsecond or more.

Further, in the present embodiment, the control unit 8 updates the control period T _p in the command discharge power P _storage ^* for the power storage device 9 has. The charge / discharge power P _storage follows the command charge / discharge power P _storage ^* of the power storage device 9. Numerical examples of the control cycle T _p are as described above.

Hereinafter, the terms first process, second process, third process and fourth process may be used. The first process is a process of reducing the first generated power P ₁ . The second process is a process for increasing the charge / discharge power P _storage . The third process is a process for increasing the first generated power P ₁ . The fourth process is a process for reducing the charge / discharge power P _storage .

As can be understood from the description with reference to FIG. 5, when the differential power P _delta is larger than zero, when the second process is executed, the control device 8 performs the first process before executing the second process. To execute. Further, when the differential power P _delta is smaller than zero, the control device 8 executes the third process before executing the fourth process when the fourth process is executed.

As described above, the control device 8 gives priority to the first process over the second process. Further, the control device 8 preferentially executes the third process over the fourth process. In this way, it is easy to suppress the charging / discharging of the power storage device 9. This makes it possible to use an inexpensive power storage device 9 having a reduced capacity. For this reason, preferentially executing the first process or the third process can contribute to the realization of an inexpensive distributed power supply system 1 suitable for a stable supply of electric power. Further, reducing the capacity of the power storage device 9 is advantageous from the viewpoint of miniaturization of the power storage device 9.

The first process corresponds to at least one step S7. The second process corresponds to at least one step S12. The third process corresponds to at least one step S9. The fourth process corresponds to at least one step S14.

In the example of FIG. 5, in the first process and the third process, altering the command first generated power P ₁ ^* should first generated power P ₁ to follow only the first step width P _WIDTH1, performed at least once .. In the second process and the fourth process, varying the charge and discharge power P _storage command charge-discharge electric power to the tracks P _storage ^* Only second step width P _Width2, performed at least once.

The first step width P _width1 and the second step width P _width2 can be set so as to ensure both responsiveness and stability of control. Typically, the first step width P _width1 and the second step width P _width2 are minute widths.

In the example of FIG. 5, the second process is started when the command first generated power P ₁ ^* reaches the lower limit power P _min by the first process. The fourth process is started when the command first generated power P ₁ ^* reaches the upper limit power P _max by the third process. By setting the lower limit power P _min and the upper limit power P _max suitable for the first power generation device 3, it is not unreasonable for the first power generation device 3 to adjust the total generated power P _sum by adjusting the first generated power P _1. Can be executed in the range.

In the example of FIG. 5, the first process and the third process are performed while maintaining the command charge / discharge power P _storage ^* at the current value. The second process is performed while maintaining the command first generated power P ₁ ^* at the lower limit power P _min . The fourth process is performed while maintaining the command first generated power P ₁ ^* at the upper limit power P _max .

The first process and the third process may be performed while maintaining the command charge / discharge power P _storage ^* at zero. This is suitable for suppressing the charging / discharging of the power storage device 9.

The upper limit power P _max is, for example, the maximum value of the first generated power P ₁ that the first power generation device 3 can currently output. The lower limit power P _min is set to, for example, a value at which the power generation efficiency is ensured in the first power generation device 3.

The upper limit power P _max and the lower limit power P _min may be changed during the operation of the distributed power supply system 1. For example, when the first power generation device 3 is the Rankine cycle power generation device shown in FIGS. 2A and 2B, the first power generation power P ₁ that can be output by the first power generation device 3 is a heating medium supplied to the evaporator 3B. It depends on the temperature, flow rate, etc. Considering this, it is rational to change the upper limit power P _max and the lower limit power P _min according to the temperature, flow rate, etc. of the heating medium. The temperature, flow rate, etc. of the heating medium can be reflected in the detection temperature of the temperature sensor 3D. Therefore, in one example of the present embodiment, the control device 8 changes the upper limit power P _max and the lower limit power P _min based on the detected temperature of the temperature sensor 3D.

The upper limit power P _max and the lower limit power P _min may be maintained constant during the operation of the distributed power supply system 1.

As can be understood from FIG. 5, the operation mode executed by the control device 8 is a first operation mode in which one of a plurality of processes including the first process, the second process, the third process, and the fourth process is selected and executed. Includes mode. The first generated power P ₁ at the start of the first mode may be larger than zero and smaller than the rated value of the first generated power P ₁ . In this way, after the first mode is started, the state in which the first generated power can be increased or decreased is likely to be continued. This is suitable for suppressing the charging / discharging of the power storage device 9. According to the operation in which charge / discharge can be easily suppressed, it is possible to use an inexpensive power storage device 9 having a reduced capacity.

The first generated power P ₁ at the start of the first mode may be a value in the range of 20% to 80% of the rated value of the first generated power P ₁ , and is 40% to 60% of the rated value. The value may be in the range of up to.

The command first generated power P ₁ ^* at the start of the first mode may be greater than zero and less than the rated value of the first generated power P ₁ , ranging from 20% to 80% of the rated value. The value may be in the range, or may be in the range of 40% to 60% of the rated value.

First generated power P ₁ ^* is the command at the start of the first mode may be a value smaller than the larger upper power limit P _max than the lower limit power P _min, between upper power limit P _max and the lower limit power P _min A value in the range of 20% to 80% of the width may be added to the lower limit power P _min, and a value in the range of 40% to 60% of the width is added to the lower limit power P _min . It may be a value.

Typically, after the lapse of several days from the start of the first mode, periodicity appears in the change of the first generated power P ₁ of the day. In one embodiment, in the first mode, the after more than 2 days from the start of the first mode, the timing and the first generated power P ₁ of the first generated power P ₁ is increased across the reference power is the reference power across in timing and the first transition of the generated power P ₁ appearing in the day to decrease, repeatedly appear across days. Here, the reference power is a power larger than zero and smaller than the rated value of the first generated power. The reference power may be a value in the range of 20% to 80% of the rated value, or may be a value in the range of 40% to 60% of the rated value.

In this embodiment, the total generated power P _sum is the sum of the generated power P ₂ of the generated power P ₁ and the second power generating apparatus 2 of the first power generating unit 3. Therefore, in the first mode, when the second generated power P ₂ increases, the first generated power P ₁ can be decreased. Further, when the second generated power P ₂ decreases, the first generated power P ₁ can be increased. As described above, in the present embodiment, the generated power P ₁ can be controlled complementarily with the generated power P ₂ .

When the second power generation device 2 is a solar power generation device, the generated power P ₂ of the second power generation device 2 fluctuates depending on the weather. However, according to the present embodiment, when the generated power P ₂ fluctuates in this way, the first generated power P ₁ can be controlled so that the fluctuation of the total generated power P _sum is suppressed. Typically, the responsiveness of the control of the generated power P ₁ of the first power generating unit 3 is higher than the responsiveness of the control of the generated power of the thermal power plant by the power company owns. In one specific example, even in a situation where the generated power P ₂ decreases for a short period of time due to the clouds crossing the sun, the first generated power P ₁ can be controlled with high responsiveness, and the fluctuation of the total generated power P _sum fluctuates. It can be suppressed.

If the differential power P _delta does not become zero even after executing the first to fourth processes, the second generated power P ₂ of the second power generation device 2 may be adjusted to bring the differential power P _delta closer to zero. For example, when the second power generation device 2 is a photovoltaic power generation device and the differential power P _delta does not become zero even if the first processing and the second processing are executed, the second power generation power P ₂ is reduced. As a result, the differential power P _delta may be brought close to zero.

In one example, the first step width P _width1 and the second step width P _width2 are fixed values. In this way, the control is easy to stabilize.

In another example, the first step width P _width1 and the second step width P _width2 are changed according to the magnitude of P _delta . Specifically, it is possible to increase the first step size P _WIDTH1 and second step size P _Width2 smaller the P _delta is large. In this way, it is possible to achieve both control stability and responsiveness. Specifically, it is possible to reduce the number of control cycles repeated until the generated power P ₁ and the charge / discharge power P _storage converge, while ensuring the stability of control. As a result, the generated power P ₁ and the charge / discharge power P _storage can be converged in a short time. This is advantageous from the viewpoint of stabilizing the specific power P _out .

One of the first step size P _WIDTH1 and second step size P _Width2, may be changed according to the size of P _delta. Specifically, may be increased one of the first step size P _WIDTH1 and second step size P _Width2 smaller the P _delta is large.

Minus the command discharge power P _storage ^* from the command total generated power P _sum ^* is a value close to the target power P _constant ^* substantially equal value or target power P _constant ^*. Specifically, P _sum ^* , P _storage ^*, and P _storage ^* can be appropriately set in consideration of the power conversion loss in the power output device 6.

In the present embodiment, the specific power P _out calculated by the power calculation unit 7C is reflected in the control by the control device 8. In one specific example, when the specific power P _out is larger than the target power P _constant ^* , the control device 8 reduces the command total generated power P _sum ^* . When the specific power P _out is smaller than the target power P _constant ^* , the control device 8 increases the command total generated power P _sum ^* . In reality, there may be factors that prevent the specific power P _out from being maintained at the target power P _constant ^* , such as the power conversion efficiency of the power output device 6 fluctuating due to load fluctuations. _{Feeding back the} specific power P _out to the control by the control device 8 in this way is useful for making the specific power P _out follow the target power P _constant ^* with high accuracy.

Hereinafter, the relationship between the generated power in the distributed power source system 1, the received power from the commercial power source 5A, and the required power of the load 5B will be described with reference to FIGS. 6A to 6E.

FIG. 6A shows a specific example of the present embodiment. In the specific example of FIG. 6A, the plurality of power generation devices 32 are two power generation devices, the first power generation device 3 and the second power generation device 2. The first power generation device 3 is a waste heat power generation device that generates power by using waste heat. The second power generation device 2 is a solar power generation device. The power storage device 9A is a storage battery.

In the following description, the generated power of the first power generation device 3 may be referred to as waste heat generated power. The generated power of the second power generation device 2 may be referred to as photovoltaic power generation. The required power of the load 5B may be referred to as a load power. The electric power received by the load 5B from the commercial power source 5A may be simply referred to as the received electric power. As described above, a value indicating the charging power of the storage battery 9A when it is positive and an absolute value indicating the discharging power of the storage battery 9A when it is negative may be referred to as charge / discharge power. The time average of the value obtained by subtracting the charge / discharge power from the total of the exhaust heat power generation power and the solar power generation power is sometimes referred to as the average output power.

The comparative example of FIG. 6B differs from the example of FIG. 6A in that there is no storage battery. In FIG. 6B, the total of the waste heat power generation power and the solar power generation power is smaller than the load power at any time. In the daytime, the photovoltaic power is large, the sum of the exhaust heat generated power and the photovoltaic power is the largest, and this total is the closest to the load power, and the received power is the smallest. On the other hand, in the night time zone, the photovoltaic power generation is zero, and the received power is the maximum when the load power is the maximum. In the comparative example of FIG. 6B, the deviation between the maximum value and the minimum value of the received power in one day is large.

The comparative example of FIG. 6C is different from the comparative example of FIG. 6B in that there is no waste heat power generation device. Further, in the comparative example of FIG. 6C, the photovoltaic power generation power is larger than that of the comparative example of FIG. 6B. In the comparative example of FIG. 6C as well as the comparative example of FIG. 6B, the received power is the minimum in the daytime time zone. In the night time zone, the received power is the maximum when the load power is the maximum. In the comparative example of FIG. 6C, the maximum value of the received power is large and the deviation between the maximum value and the minimum value of the received power in one day is large as compared with the comparative example of FIG. 6B.

In the comparative example of FIG. 6D, the photovoltaic power generation is larger than that of the comparative example of FIG. 6C. Specifically, in the comparative example of FIG. 6D, the daily power generation amount of the photovoltaic power generation device is the same as the total daily power generation amount of the exhaust heat power generation device and the photovoltaic power generation device in the comparative example of FIG. 6B. As described above, it is assumed that photovoltaic power generation can be obtained. In the comparative example of FIG. 6D, the maximum value of the photovoltaic power generation is large. At some time during the daytime when this maximum value appears, this maximum value is larger than the received power. Therefore, at this time, the received power is negative, that is, a reverse power flow from the distributed power supply system to the commercial power supply occurs. Further, also in the comparative example of FIG. 6D, the photovoltaic power generation power is zero and the load power is the maximum in the night time zone. In the comparative example of FIG. 6D, the deviation between the maximum value and the minimum value of the received power in one day is larger than that of the comparative example of FIG. 6C.

The comparative example of FIG. 6E is different from the example of FIG. 6A in that there is no waste heat power generation device and that the photovoltaic power generation power is large as in the comparative example of FIG. 6D. In the comparative example of FIG. 6E, charging and discharging are performed by the storage battery, and reverse power flow does not occur. Further, in the comparative example of FIG. 6E, the deviation between the maximum value and the minimum value of the received power in one day is smaller than that of the comparative example of FIGS. 6B to 6D. However, the photovoltaic power generation is zero in the night time zone, and the photovoltaic power generation power is large in the daytime zone. Therefore, the charge / discharge power of the storage battery and the amount of power stored in the storage battery can be large. Therefore, in the comparative example of FIG. 6E, a large-capacity storage battery is required.

On the other hand, in the specific example of the present embodiment shown in FIG. 6A, the waste heat power generation device 3, the solar power generation device 2, and the storage battery 9A are combined. Further, in this specific example, the control described with reference to the flowchart of FIG. 5 is performed. Therefore, the charge / discharge power of the storage battery 9A and the amount of power stored in the storage battery 9A can be suppressed. Therefore, in this specific example, it is possible to reduce the deviation between the maximum value and the minimum value of the received power in one day while using the storage battery 9A having a small capacity.

It is not essential to make P _out follow a constant target power. This disclosure is
A plurality of power generation devices 32 including the first power generation device 3 and
A power storage device 9 connected to a plurality of power generation devices 32,
A power output device 6 including a power input unit 6i connected to a plurality of power generation devices 32 and a power storage device 9 and a power output unit 6о connected to a commercial power source 5A.
With a control device 8
The power generated by the first power generation device 3 is defined as the first power generation power P _1, and when it is positive, it indicates the charging power of the power storage device 9, and when it is negative, the absolute value indicates the discharge power of the power storage device 9. When is defined as the charge / discharge power P _{storage of the} power storage device 9, the control device 8
Calculate the differential power P _delta by subtracting the command total power generation power P _sum ^* from the total power generation power P _sum of the plurality of power generation devices 32.
When the differential power P _delta is larger than zero, when the second process of increasing the charge / discharge power P _storage is executed, the first process of decreasing the first generated power P ₁ is performed before the second process is executed. Run and
When the differential power P _delta is smaller than zero, when the fourth process of reducing the charge / discharge power P _storage is executed, the third process of increasing the first generated power P ₁ is performed before the fourth process is executed. Run,
It can also be considered to provide the distributed power supply system 1. Such a distributed power supply system can be an inexpensive system suitable for a stable supply of electric power.

Similarly, this disclosure
A plurality of power generation devices 32 including the first power generation device 3 and
A power storage device 9 connected to a plurality of power generation devices 32,
Controls a distributed power supply system 1 including a power output device 6 including a power input unit 6i connected to a plurality of power generation devices 32 and a power storage device 9 and a power output unit 6о connected to a commercial power source 5A. Control device 8
The power generated by the first power generation device 3 is defined as the first power generation power P _1, and when it is positive, it indicates the charging power of the power storage device 9, and when it is negative, the absolute value indicates the discharge power of the power storage device 9. When is defined as the charge / discharge power P _{storage of the} power storage device 9, the control device 8
Calculate the differential power P _delta by subtracting the command total power generation power P _storage from the total power generation power P _sum of the plurality of power generation devices 32.
When the differential power P _delta is larger than zero, when the second process of increasing the charge / discharge power P _storage is executed, the first process of decreasing the first generated power P ₁ is performed before the second process is executed. Run and
When the differential power P _delta is smaller than zero, when the fourth process of reducing the charge / discharge power P _storage is executed, the third process of increasing the first generated power P ₁ is performed before the fourth process is executed. Run,
It can also be considered to provide the control device 8.

Similarly, this disclosure
A plurality of power generation devices 32 including the first power generation device 3 and
A power storage device 9 connected to a plurality of power generation devices 32,
Controls a distributed power supply system 1 including a power output device 6 including a power input unit 6i connected to a plurality of power generation devices 32 and a power storage device 9 and a power output unit 6о connected to a commercial power source 5A. It is a control method to
The power generated by the first power generation device 3 is defined as the first power generation power P _1, and when it is positive, it indicates the charging power of the power storage device 9, and when it is negative, the absolute value indicates the discharge power of the power storage device 9. _Is defined as the charge / discharge power P _{storage of the} power storage device 9.
The difference power P _delta obtained by subtracting the command total power generation power P _storage from the total power generation power P _sum of the plurality of power generation devices 32 is calculated.
When the differential power P _delta is larger than zero, when the second process of increasing the charge / discharge power P _storage is executed, the first process of decreasing the first generated power P ₁ is performed before the second process is executed. To do and
When the differential power P _delta is smaller than zero, when the fourth process of reducing the charge / discharge power P _storage is executed, the third process of increasing the first generated power P ₁ is performed before the fourth process is executed. To do and
It can also be thought of as providing a control method, including.

According to the technique according to the present disclosure, it is possible to stabilize the total of the generated power of the power generation device having the power generation adjusting power and the generated power of the power generation device using the renewable energy. Examples of the power generation device having the power generation adjusting power include a power generation device power generation using exhaust heat, a power generation device using a fuel cell, and the like. Examples of the power generation device using renewable energy include a power generation device power generation using sunlight, a power generation device using wind power, and the like.

1 Distributed power supply system 2, 3 Power generation device 2A, 3R Power generation power supply 2B, 3H, 9B Power converter 3A Pump 3B Evaporator 3C Expander 3D Temperature sensor 3E Bypass valve 3F Condenser 3G Generator 4, 7 Detector 5A Commercial Power supply 5B Load 6 Power output device 7A Current detector 7B Voltage detector 7C Power calculation unit 8 Control device 9 Power storage device 9A Power storage device 10, 11, 13, 16, 17, 18, 19, 20, 21 Switching elements 12, 15 Reactors 14, 51, 52, 53, 54, 55, 56, 57, 58, 59 Diodes 22, 41, 42, 46, 47 Capacitors 35, 36 Electric circuit 60 Switching circuits 61, 62, 63 Phase circuits 66, 67, 68 Connection point

Claims (9)

Multiple power generation devices including the first power generation device,
A power storage device connected to the plurality of power generation devices and
A power output device including a power input unit connected to the plurality of power generation devices and the power storage device, and a power output unit connected to a commercial power source.
The first detector and
It is provided with a control device that causes a specific power, which is a value representing the power output from the power output unit and is a value specified by using the first detection device, to follow a constant target power.
The power generated by the first power generation device is defined as the first power generation power, and when it is positive, it refers to the charging power of the power storage device, and when it is negative, the absolute value indicates the discharge power of the power storage device. When defined as the charge / discharge power of the power storage device, the control device is defined as
Calculate the differential power obtained by subtracting the command total power generation power from the total power generation power of the plurality of power generation devices.
When the differential power is larger than zero, when the second process of increasing the charge / discharge power is executed, the first process of reducing the first generated power is executed before the second process is executed. ,
When the differential power is smaller than zero, when the fourth process of reducing the charge / discharge power is executed, the third process of increasing the first generated power is executed before the fourth process is executed. ,
Distributed generation system. The control device updates the command first generated power of the first power generation device at a certain control cycle.
The first generated power follows the commanded first generated power of the first power generation device.
The control cycle is 1 millisecond or less.
The distributed power supply system according to claim 1. The first power generation device is a thermoelectric power generation device or a fuel cell power generation device that uses heat to generate power.
The distributed power supply system according to claim 1 or 2. The plurality of power generation devices include a second power generation device.
The second power generation device is a power generation device that uses renewable energy.
The distributed power supply system according to any one of claims 1 to 3. The second power generation device is a solar power generation device or a wind power generation device.
The distributed power supply system according to claim 4. The control device sets a lower limit power which is a lower limit of the command first generated power to be followed by the first generated power and an upper limit power which is an upper limit of the command first generated power.
When the command first generated power reaches the lower limit power by the first process, the second process is started.
When the command first generated power reaches the upper limit power by the third process, the fourth process is started.
The distributed power supply system according to any one of claims 1 to 5. The operation mode executed by the control device includes a first mode in which one of a plurality of processes including the first process, the second process, the third process, and the fourth process is selected and executed.
The first generated power at the start of the first mode is greater than zero and less than the rated value of the first generated power.
The distributed power supply system according to any one of claims 1 to 6. Multiple power generation devices including the first power generation device,
A power storage device connected to the plurality of power generation devices and
A power output device including a power input unit connected to the plurality of power generation devices and the power storage device, and a power output unit connected to a commercial power source.
A distributed power supply system including a first detection device has a specific power target, which is a value representing the power output from the power output unit and is a value specified by using the first detection device. It is a control device that controls to follow the electric power.
The power generated by the first power generation device is defined as the first power generation power, and when it is positive, it refers to the charging power of the power storage device, and when it is negative, the absolute value indicates the discharge power of the power storage device. When defined as the charge / discharge power of the power storage device, the control device is defined as
Calculate the differential power obtained by subtracting the command total power generation power from the total power generation power of the plurality of power generation devices.
When the differential power is larger than zero, when the second process of increasing the charge / discharge power is executed, the first process of reducing the first generated power is executed before the second process is executed. ,
When the differential power is smaller than zero, when the fourth process of reducing the charge / discharge power is executed, the third process of increasing the first generated power is executed before the fourth process is executed. ,
Control device. Multiple power generation devices including the first power generation device,
A power storage device connected to the plurality of power generation devices and
A power output device including a power input unit connected to the plurality of power generation devices and the power storage device, and a power output unit connected to a commercial power source.
A distributed power supply system including a first detection device is provided with a specific power target, which is a value representing the power output from the power output unit and is a value specified by using the first detection device. It is a control method that controls to follow the electric power.
The power generated by the first power generation device is defined as the first power generation power, and when it is positive, it refers to the charging power of the power storage device, and when it is negative, the absolute value indicates the discharge power of the power storage device. When defined as the charge / discharge power of a power storage device,
To calculate the differential power obtained by subtracting the command total power generation power from the total power generation power of the plurality of power generation devices.
When the differential power is larger than zero, when the second process of increasing the charge / discharge power is executed, the first process of reducing the first generated power is executed before the second process is executed. That and
When the differential power is smaller than zero, when the fourth process of reducing the charge / discharge power is executed, the third process of increasing the first generated power is executed before the fourth process is executed. That and
Control methods, including.

Images