JP7241302B2 - DISTRIBUTED POWER SYSTEM, CONTROL DEVICE AND CONTROL METHOD - Google Patents

Description

The present disclosure relates to a distributed power supply system, control device and control method.

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

A 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 system interconnection device 108 , and a general control device 109 .

Power generator 110 generates power using renewable energy. Specifically, power generation device 110 is a solar power generation device. Power generation device 110 includes solar cell 101 and DC-DC converter 103 . The DC-DC converter 103 converts the DC voltage output from the solar cell 101 into a DC voltage of a predetermined magnitude.

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

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

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

JP 2012-75224 A

The present disclosure provides technology that can contribute to the realization of an inexpensive distributed power supply system that is suitable for stabilizing power supplied from commercial power supplies to loads.

This disclosure is
a plurality of power generators including a first power generator;
a power storage device connected to the plurality of power generation devices;
a power output device including a power input section connected to the plurality of power generation devices and the power storage device, and a power output section connected to a commercial power supply via a branch section to which a load is connected;
a detection device;
a control device that causes the specific power, which is a value representing the power received from the commercial power supply and is specified using the detection device, to follow a constant target power;
The power generated by the first power generation device is defined as the first power generation, and the value indicating the charging power of the power storage device when positive and the absolute value when negative indicates the discharging power of the power storage device When defined as the charge/discharge power of a power storage device, the control device
calculating a differential power obtained by subtracting the specific power from the target power;
When the differential power is greater than zero, when executing the second process of increasing the charge/discharge power, the first process of decreasing the first generated power is executed before executing the second process. ,
When the differential power is smaller than zero, when executing the fourth process of decreasing the charge/discharge power, executing the third process of increasing the first generated power before executing the fourth process. ,
To provide a distributed power system.

The technology according to the present disclosure can contribute to the realization of an inexpensive distributed power supply system that is suitable for stabilizing power supplied from commercial power supplies to loads.

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

(Findings on which this disclosure is based)
A power generation device using renewable energy such as sunlight is known. The power generated by such a power generator tends to fluctuate depending on the natural environment. Patent Literature 1 describes that fluctuations in generated power are absorbed by a power storage device.

However, the power generated by a power generator using renewable energy can fluctuate greatly. For this reason, when the power storage device absorbs fluctuations in generated power according to Patent Document 1, a large-capacity power storage device is required. However, large-capacity power storage devices are expensive.

Patent Literature 1 also describes that a target value for the remaining amount of charge of the power storage device is set based on predicted data on the amount of power generation. However, predictions may not come true. If the prediction is wrong, the power storage device may be in a fully charged state or an over-discharged state. Under these conditions, fluctuations in generated power may not be absorbed.

Here, it is considered that the required power of the load is covered by the power generated by the power generator using renewable energy and the power received from the commercial power supply. In this case, when the generated power fluctuates, the received power fluctuates accordingly.

When the power received from the commercial power source is unstable, it is difficult to balance the supply and demand of power, and the voltage of the commercial power source tends to fluctuate.

For the above reasons, a technique for realizing an inexpensive distributed power supply system that is suitable for stabilizing power supplied from a commercial power supply to loads deserves consideration.

(Overview of one aspect of the present disclosure)
A distributed power supply system according to a first aspect of the present disclosure includes:
a plurality of power generators including a first power generator;
a power storage device connected to the plurality of power generation devices;
a power output device including a power input section connected to the plurality of power generation devices and the power storage device, and a power output section connected to a commercial power supply via a branch section to which a load is connected;
a detection device;
a control device that causes the specific power, which is a value representing the power received from the commercial power supply and is specified using the detection device, to follow a constant target power;
The power generated by the first power generation device is defined as the first power generation, and the value indicating the charging power of the power storage device when positive and the absolute value when negative indicates the discharging power of the power storage device When defined as the charge/discharge power of a power storage device, the control device
calculating a differential power obtained by subtracting the specific power from the target power;
When the differential power is greater than zero, when executing the second process of increasing the charge/discharge power, the first process of decreasing the first generated power is executed before executing the second process. ,
When the differential power is smaller than zero, when executing the fourth process of decreasing the charge/discharge power, executing the third process of increasing the first generated power before executing the fourth process. .

The technology according to the first aspect can contribute to the realization of an inexpensive distributed power supply system that is suitable for stabilizing power supplied to loads from a commercial power supply.

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 command first generated power possessed by the first power generator,
The control cycle may be 1 millisecond or less.

The second mode 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 aspect or the second aspect,
The first power generator may be a thermal power generator that uses heat to generate power, or a fuel cell power generator.

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

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 generators may include a second power generator,
The second power generator may be a power generator using renewable energy.

The second power generator of the fourth aspect utilizes renewable energy. Such a second power generation device has an advantage that the environmental load is small and a disadvantage that the generated power may fluctuate depending on the natural environment. However, the second power plant of the fourth aspect is combined with the technique of the first aspect. As a result, the above advantages can be obtained while suppressing the above 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 generator of the fifth aspect is a specific example of a power generator 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 that is a lower limit of the command first generated power that the first generated power should follow, and an upper limit power that 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, it is possible to adjust the power received from the commercial power supply by adjusting the first generated power within a reasonable range for the first power generator.

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 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 a 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 continue. This is suitable for suppressing charging and discharging of the power storage device. According to the operation in which charging/discharging is easily suppressed, it becomes possible to use an inexpensive power storage device with a suppressed capacity.

In the eighth aspect of the present disclosure, for example, the distributed power supply system according to any one of the first to seventh aspects,
an AC electric line extending from the power output to the commercial power supply and including a first portion between the power output and the branch and a second portion between the branch and the commercial power;
a branch electric circuit extending from the branch portion to the load,
The detection device is
(i) may include a current detector provided in said second portion, or
(ii) A current detector provided in the branch electric line may be included.

The current detector of the eighth aspect helps identify the specific power.

A control device according to a ninth aspect of the present disclosure includes:
a plurality of power generators including a first power generator;
a power storage device connected to the plurality of power generation devices;
a power output device including a power input section connected to the plurality of power generation devices and the power storage device, and a power output section connected to a commercial power supply via a branch section to which a load is connected;
and a detection device for causing a distributed power supply system to follow a certain target power with a specific power, which is a value representing the power received from the commercial power supply and is specified using the detection device. A controller for controlling,
The power generated by the first power generation device is defined as the first power generation, and the value indicating the charging power of the power storage device when positive and the absolute value when negative indicates the discharging power of the power storage device When defined as the charge/discharge power of a power storage device, the control device
calculating a differential power obtained by subtracting the specific power from the target power;
When the differential power is greater than zero, when executing the second process of increasing the charge/discharge power, the first process of decreasing the first generated power is executed before executing the second process. ,
When the differential power is smaller than zero, when executing the fourth process of decreasing the charge/discharge power, executing the third process of increasing the first generated power before executing the fourth process. .

The technique according to the ninth aspect can contribute to the realization of an inexpensive distributed power supply system suitable for stabilizing the power supplied from the commercial power supply to the load.

A control method according to a tenth aspect of the present disclosure includes:
a plurality of power generators including a first power generator;
a power storage device connected to the plurality of power generation devices;
a power output device including a power input section connected to the plurality of power generation devices and the power storage device, and a power output section connected to a commercial power supply via a branch section to which a load is connected;
and a detection device for causing a distributed power supply system to follow a certain target power with a specific power, which is a value representing the power received from the commercial power supply and is specified using the detection device. A control method for controlling,
The power generated by the first power generation device is defined as the first power generation, and the value indicating the charging power of the power storage device when positive and the absolute value when negative indicates the discharging power of the power storage device When defined as the charge/discharge power of a power storage device,
calculating a differential power obtained by subtracting the specific power from the target power;
When the differential power is greater than zero, when executing the second process of increasing the charge/discharge power, the first process of decreasing the first generated power is executed before executing the second process. and
When the differential power is smaller than zero, when executing the fourth process of decreasing the charge/discharge power, executing the third process of increasing the first generated power before executing the fourth process. and
including.

The technology according to the tenth aspect can contribute to the realization of an inexpensive distributed power supply system that is suitable for stabilizing power supplied to loads from a commercial power supply.

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

(Embodiment 1)
FIG. 1A shows a distributed power supply system 1 according to Embodiment 1. As shown in FIG.

The distributed power supply system 1 shown in FIG. 1A includes a plurality of power generators 32, a power output device 6, a control device 8, a power storage device 9, and a detection device 71.

The power generators 32, the power storage device 9, and the power output device 6 are connected to each other. Specifically, this connection is made via a DC electric line 35 .

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

Electric power generated by the plurality of power generation devices 32 can be supplied to the power storage device 9 . The power generated by the plurality of power generators 32 and the power stored in the power storage device 9 can be supplied to the load 5B via the power output device 6 . Power may 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 cover the required power of the load 5B, the shortfall of power is supplied from the commercial power supply 5A to the load 5B. There is no reverse power flow from the distributed power supply system 1 to the commercial power supply 5A.

In another example, power may reversely flow from the distributed power supply system 1 to the commercial power supply 5A.

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

The constituent elements of the distributed power supply system 1 will be described below.

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

The first power generator 3 is connected to the DC electric circuit 35 . The first power generator 3 has power generation adjustment capability. Having power generation adjustment capability means that the power generated by itself can be increased or decreased by being controlled. In this embodiment, the power generated by the first power generation device 3 can be controlled by the control device 8 to increase or decrease sequentially.

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

The power generation power source 3R generates power. The power generation power source 3R has power generation adjustment capability. In this embodiment, the power generated by the power generation source 3R can be controlled by the control device 8 to increase or decrease sequentially.

Below, the generated power of the first power generator 3 may be referred to as 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 line 35 . In the example of FIG. 1A, the first generated power _P1 is the output power of the power converter 3H.

In the present embodiment, the first power generator 3 is a thermal power generator that uses heat to generate power. Specifically, the first power generation device 3 is an exhaust heat power generation device that generates power using exhaust heat. Moreover, in this Embodiment, the 1st electric power generating apparatus 3 is a Rankine-cycle electric power generating apparatus.

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 using exhaust heat. Moreover, in this embodiment, the power generation source 3R is a Rankine cycle power source.

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

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

The first power generator 3, which is a thermoelectric generator, may be referred to as a thermoelectric generator 3 hereinafter. The first power generation device 3 that is an exhaust heat power generation device may be referred to as an exhaust heat power generation device 3 . The first power generator 3, which is a Rankine cycle power generator, may be referred to as the Rankine cycle power generator 3. The power source 3R, which is a Rankine cycle power source, may be referred to as the Rankine cycle 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 generator 3 is a fuel cell power generator. 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 the present embodiment, the Rankine cycle power generation device 3 includes a Rankine cycle power generation power supply 3R and an AC-DC converter 3H.

FIG. 2A shows a Rankine cycle 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.

A coolant circulation path is formed in the Rankine cycle power generation power supply 3R. In this circuit, a pump 3A, an evaporator 3B, an expander 3C, and a 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 taking heat from the refrigerant. The heat taken by the condenser 3F is given to the cooling medium.

In this embodiment, the heating medium is gas. Specifically, the heating medium is exhaust gas. In other words, the Rankine cycle power source 3R is a power source using waste heat. The source of the exhaust gas is, for example, a factory, in one embodiment a furnace, which may be a furnace used in the production of castings. 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 gas. Specifically, the cooling medium is atmospheric air. However, the cooling medium may be liquid such as water. The condenser 3F may be equipped with a fan. The condenser 3F is, for example, a fin-and-tube heat exchanger, a plate heat exchanger, or a double tube heat exchanger.

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

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

The bypass valve 3E may be a flow control valve or an on-off valve. Here, the flow rate control valve is a valve that can take an opening degree larger than 0% and smaller than 100%. The on-off valve is a valve whose degree of opening is set to either of two values of 0% and 100%.

The temperature sensor 3D is provided in a portion of the circulation path downstream of the evaporator 3B and upstream of the expander 3C. A temperature sensor 3D detects the temperature of the coolant in this portion. A temperature sensor 3D can be used to control the components of the Rankine cycle power plant 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 temperature detected by the temperature sensor 3D can be substantially the inlet temperature of the expander 3C.

The generator 3G is connected to the expander 3C. Rotational energy is generated by the expansion in the expander 3C. In the generator 3G, the rotor rotates due to the rotational energy. Thus, AC power is generated in the generator 3G.

AC-DC converter 3H is connected to 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.

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

A first phase circuit 61, a second phase circuit 62, and a third phase circuit 63 are configured in the AC-DC converter 3H. 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 this embodiment, the first phase circuit 61, the second phase circuit 62 and the third phase circuit 63 are respectively connected to the first, second and third phases of the generator 3G. In this embodiment, the first, second and third phases are U, V and W phases, respectively.

First phase circuit 61 includes switching elements 16 and 17 and diodes 51 and 52 . 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.

Second phase circuit 62 includes switching elements 18 and 19 and diodes 53 and 54 . 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.

Third phase circuit 63 includes switching elements 20 and 21 and diodes 55 and 56 . 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 this 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 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 regenerative braking to the generator 3G to obtain regenerative electric power. A controller 8 controls the AC-DC converter 3H. Capacitor 22 absorbs the instantaneous pulsation of regenerated power.

In one embodiment, the switching elements 16-21 are driven with Pulse Width Modulation (PWM). More specifically, a PWM signal is provided to switching elements 16-21. The switching elements 16 to 21 are switched based on the PWM signal.

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

As can be understood from the above description, in the present embodiment, the first power generation device 3 includes a power generator 3G that generates power by rotation of the rotor, and a power converter 3H that includes the 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 rotational speed of the generator 3G using the AC-DC converter 3H. This control can be performed by the controller 8 .

A configuration may also be adopted in which the flow rate of the refrigerant flowing through the circulation path is controlled by controlling the rotation speed of the pump 3A, thereby controlling the first generated power _P1 . A configuration may also be adopted in which the opening degree of the bypass valve 3E is controlled to control the flow rate of the refrigerant flowing through the circulation path, thereby controlling the first generated power _P1 . In addition, a configuration is adopted in which a brake circuit is provided in the first power generation device 3 and part of the DC power obtained by the first power generation device 3 is consumed in the brake circuit to control the first generated power _P1 . obtain. These controls can also be performed by the controller 8 . Combining two or more selected from control of the rotation (specifically, the number of rotations) of the rotor, control of the number of rotations of the pump 3A, control of the opening degree of the bypass valve 3E, and power consumption by the brake circuit, the first power generation A configuration that controls power P ₁ may also be employed.

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

As will be appreciated from the above description, control of rotor rotation using a switching circuit may be employed when the first power plant is a Rankine cycle power plant. Alternatively, this control may be employed when the first power plant is another type of power plant, provided that the first power plant has a rotor. Of course, if the first power generator is a thermal power generator such as an exhaust heat power generator and has a rotor, this control is adopted regardless of whether the first power generator is a Rankine cycle power generator. can be

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 may include the same number of power converters as the number of power generation sources, and the plurality of power generation sources and the plurality of power converters may be connected one-to-one. In this case, the power generation source and power converter can be the elements exemplified as power generation source 3R and power converter 3H. The plurality of power sources may be different types of power sources, such as one power source being a Rankine cycle power source and another power source being a fuel cell. Also, the plurality of power sources may be of the same type, such that one power source and another power source are Rankine cycle power sources. This point is the same for a plurality of power converters. Also, in this case, the power output by the first power generation device 3 due to power generation by the plurality of power generation sources will be referred to as first power generation P ₁ .

Returning to FIG. 1A, the second power generator 2 is connected to the DC electric line 35 . During the operation of the second power generation device 2, the power generated by the second power generation device 2 may fluctuate depending on the weather or the like. Specifically, the second power generator 2 is a power generator using renewable energy.

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

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

Below, the 2nd power generation device 2 which is a solar power generation device may be described with the solar power generation device 2. As shown in FIG. 2 A of power generation power supplies which are a solar cell may be described as 2 A of solar cells. 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 generator 2 is a wind power generator. Specifically, the power generation source 2A is a windmill. The power converter 2B is a power converter combining an AC-DC converter and a DC-DC converter.

FIG. 3 shows a specific example of the second power generator 2 according to this 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 the DC chopper circuit 2B.

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

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

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

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

Specifically, a DC voltage is input from the solar cell 2A to the DC chopper circuit 2B. Switching of the switching element 13 is controlled. When switching element 13 is on, current flows from solar cell 2A to reactor 15 and switching element 13 in this order, and energy is stored in reactor 15 . When switching element 13 is off, current flows from solar cell 2A to reactor 15 and diode 14 in this order, and the energy stored in reactor 15 is output via diode 14 . With such an operation, the DC chopper circuit 2B boosts the DC voltage input from the solar cell 2A and supplies the current to the diode 14, thereby transferring the power to the DC electric line 35. A controller 8 controls the DC chopper circuit 2B.

In one embodiment, the switching element 13 is driven with pulse width modulation. More specifically, a PWM signal is supplied to switching element 13 . 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 performed. More specifically, the DC chopper circuit 2B is used to control the output current of the solar cell 2A so that the power generated by 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 also be employed when the power generation source 2A is not a solar cell.

Below, the generated power of the 2nd power generator 2 may be called 2nd generated power _P2 . Specifically, the second generated power _P2 is DC power. The generated power P ₂ is output to the DC electric line 35 . In the example of FIG. 1A, the generated power _P2 is the output power of the power converter 2B.

Also, hereinafter, the sum of the power generated by the plurality of power generators 32 may be referred to as the total power generated _Psum . In the present embodiment, the total generated power P _sum is the sum of the generated power P ₁ of the first power generator 3 and the power generated P ₂ of the second power generator 2 .

The number of power generation sources included in the second power generator 2 is not limited to one. This number may be plural. In this case, the second power generation device 2 may include the same number of power converters as the number of power generation sources, and the plurality of power generation sources and the plurality of power converters may be connected one-to-one. In this case, the power generation source and power converter can be the elements exemplified as power generation source 2A and power converter 2B. The plurality of power generation sources may be different types of power generation sources. Also, the plurality of power sources may be of the same type. This point is the same for a plurality of power converters. Also, in this case, the power output by the second power generation device 2 due to power generation by the plurality of power generation sources will be referred to as second power generation _P2 .

Returning to FIG. 1A, the power storage device 9 is connected to multiple power generation devices 32 . Electric power generated by a plurality of power generators 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 DC electric lines 35 . The power storage device 9 can function as a power buffer when there is an excess or deficiency in the power generated by the plurality of power generation devices 32 .

In this 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 line 35 .

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

In this embodiment, the power storage 9A is a storage battery. Below, 9 A of storage batteries which are storage batteries may be described as 9 A of storage batteries. Specific examples of the storage battery that constitutes the power storage 9A are a lithium ion battery, a nickel-metal hydride battery, a lead storage battery, and the like.

Another example of the storage battery 9A is a capacitor. A specific example of the capacitor that constitutes the power storage 9A is an electric double layer capacitor.

In this embodiment, power converter 9B is a DC-DC converter. Specifically, the power converter 9B is a bidirectional DC-DC converter. More specifically, power converter 9B is a bidirectional chopper circuit. Below, the power converter 9B which is a bidirectional DC chopper circuit may be described as the bidirectional DC chopper circuit 9B.

Here, the bidirectional DC-DC converter converts the DC voltage input from its first terminal into DC voltages of different magnitudes and outputs them to its second terminal, and It refers to a converter capable of both converting a DC voltage into DC voltages of different magnitudes and outputting them to its first terminal.

Similarly, the bidirectional chopper circuit converts the DC voltage input from its first terminal into DC voltages of different magnitudes and outputs them to its second terminal, and the DC voltage input from its second terminal. to convert DC voltages of different magnitudes and output them to its first terminal.

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

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

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

Diode 59, reactor 12, and storage battery 9A are connected in this order. A current can flow through diode 59, reactor 12, and storage battery 9A in this order.

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

9 A of storage batteries, the reactor 12, the diode 58, and the DC electric line 35 are connected in this order. Current can flow through storage battery 9A, reactor 12, diode 58 and DC electric line 35 in this order.

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

When the storage battery 9A is discharged, the switching element 10 is kept off. Switching of the switching element 11 is controlled. When switching element 11 is on, current flows from storage battery 9A to reactor 12 and switching element 11 in this order, and energy is stored in reactor 12 . When switching element 11 is off, current flows from storage battery 9A to reactor 12 and diode 58 in this order, and the energy stored in reactor 12 is output via diode 58 . With such an operation, the bidirectional chopper circuit 9B functions as a boost chopper. In other words, the bidirectional chopper circuit 9B boosts the DC voltage input from the storage battery 9A and supplies the current to the diode 58, thereby conveying power to the DC electric line 35. FIG.

Control using the bidirectional chopper circuit 9B is performed by the controller 8. FIG.

In one embodiment, the switching element 10 is driven with pulse width modulation. More specifically, a PWM signal is supplied to switching element 10 . The switching element 10 switches based on the PWM signal. The same applies to the switching element 11 as well.

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

In addition, in the DC chopper circuit 2B shown in FIG. 3, the diode 14 may be changed to the switching element X, and synchronous rectification using the switching element X and the switching element 13 may be performed. 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 MOSFETs, for example. However, 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 also be employed when the storage battery 9A is not a storage battery.

Below, the charging/discharging electric power of the electrical storage apparatus 9 may be written 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 charging/discharging power P _storage is input/output to/from the DC electric circuit 35 . In the example of FIG. 1A, 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 power storage device 9 is not limited to one. This number may be plural. In this case, the power storage device 9 may include the same number of power converters as the power storage devices, and a plurality of power storage devices and a plurality of power converters may be connected one-to-one. In this case, the storage battery and the power converter can be the elements illustrated as the storage battery 9A and the power converter 9B. The plurality of power storage devices may be different types of power storage devices. Also, the plurality of power storage devices may be of the same type. This point is the same for a plurality of power converters. Also, in this case, the power charged and discharged by the second power generation device 2 by charging and discharging a plurality of electric power storages is referred to as charging and discharging power P _storage .

Returning to FIG. 1A, the power output device 6 includes a power input section 6i and a power output section 6?.

The power input unit 6 i is connected to the power generators 32 and the power storage device 9 . Specifically, the power input unit 6 i is connected to the plurality of power generators 32 and the power storage device 9 via the DC electric line 35 .

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

DC power is input to the power input unit 6 i from the plurality of power generators 32 and the power storage device 9 . AC power is output from the power output unit 6?. Power is DC-AC converted between power input 6i and power output 6?.

Specifically, power obtained by subtracting the charge/discharge power P _storage of the power storage device 9 from the total generated power P _sum is input to the power input unit 6i. In other words, when the power storage device 9 is charged, power obtained by subtracting the charging power of the power storage device 9 from the total generated power _Psum is input to the power input unit 6i. When power storage device 9 is being discharged, power obtained by summing total generated power P _sum and the discharged power of power storage device 9 is input to power input unit 6i. As described above, the total generated power P _sum is the total power generated by the plurality of power generators 32 .

Alternatively, the power is DC-DC converted and then DC-AC converted between power input 6i and power output 6o.

As shown in FIG. 1A, an AC electric line 36 extends from the power output section 6? to the commercial power source 5A. The AC electric line 36 includes a first portion 36a and a second portion 36b. The first portion 36a is a portion between the power output portion 6? and the branch portion BP. The second portion 36b is a portion between the branch portion BP and the commercial power supply 5A. The branch electric line 37 extends from the branch portion BP to the load 5B.

The distributed power supply system 1 is configured to be able to specify the specific power P _grid . Here, the specific power P _grid is a value representing the power received from the commercial power supply 5A. Further, the specified power P _grid is a value specified using the detection device PD. In this embodiment, the specific power P _grid represents the active power received from the commercial power supply 5A.

In the example of FIG. 1A, the distributed power supply system 1 includes a detection device 71 as the detection device PD. A specific power P _grid is identified using the detection device 71 . The detection device 71 includes a current detector 71A, a voltage detector 71B, and a power calculator 71C.

A current detector 71A is provided in the second portion 36b. The current detector 71A detects alternating current flowing through the position where it is provided. In the present embodiment, current detector 71A detects AC current received from commercial power supply 5A.

The voltage detector 71B is provided on the AC electric line 36 . Specifically, the voltage detector 71B is provided in the first portion 36a. The voltage detector 71B detects an AC voltage applied to the position where it is provided. In the present embodiment, voltage detector 71B detects AC voltage received from commercial power supply 5A.

The voltage detector 71B may be provided in the second portion 36b. Also, the voltage detector 71B may be provided in the branch electric line 37 .

The power calculator 71C calculates the specific power P _grid using the current detected by the current detector 71A and the voltage detected by the voltage detector 71B.

The example of FIG. 1B can also be adopted. In the example of FIG. 1B, the distributed power supply system 1 includes a detection device 81 as the detection device PD. A specific power P _grid is identified using the detection device 81 . The detection device 81 includes a current detector 81A, a voltage detector 81B, and a power calculator 81C.

A current detector 81A is provided in the branch electric line 37 . The current detector 81A detects an alternating current flowing through the position where it is provided. In this embodiment, the current detector 81A detects alternating current supplied to the load 5B.

A voltage detector 81B is provided in the AC electric line 36 . Specifically, the voltage detector 81B is provided in the first portion 36a. The voltage detector 81B detects an AC voltage applied to the position where it is provided. In the present embodiment, voltage detector 81B detects AC voltage supplied to load 5B.

The voltage detector 81B may be provided in the second portion 36b. Also, the voltage detector 81B may be provided in the branch electric line 37 .

Power calculator 81C calculates load power P _load using the current detected by current detector 81A and the voltage detected by voltage detector 81B. The load power P _load represents AC power supplied to the load 5B. In this example, the load power P _load represents the real power supplied to the load 5B.

Furthermore, in the example of FIG. 1B, the distributed power supply system 1 comprises a detection device 7 . The detection device 7 includes a current detector 7A, a voltage detector 7B, and a power calculator 7C.

The current detector 7A is provided in the first portion 36a. The current detector 7A detects alternating current flowing through the position where it is provided. In the present embodiment, current detector 7A detects alternating current output from power output device 6 .

The voltage detector 7B is provided on the AC electric line 36 . Specifically, the voltage detector 7B is provided in the first portion 36a. The voltage detector 7B detects an AC voltage applied to the position where it is provided. In this embodiment, voltage detector 7B detects the voltage output from power output device 6 .

The voltage detector 7B may be provided in the second portion 36b. Also, the voltage detector 7</b>B may be provided in the branch electric line 37 .

The power calculator 7C calculates the output power P _out using the current detected by the current detector 7A and the voltage detected by the voltage detector 7B. The output power P _out represents the AC power output from the power output device 6 . In this example, the output power P _out represents the active power output from the power output device 6 .

Furthermore, in the example of FIG. 1B, the distributed power supply system 1 comprises a computing device 85. The computing device 85 computes the specific power P _grid using the output power P _out and the load power P _load . Specifically, the computing device 85 computes the specific power P _grid by subtracting the output power P _out from the load power P _load .

In the example of FIG. 1A, the detection device 71 includes a current detector 71A provided on the second portion 36b. In the example of FIG. 1B, detection device 81 includes a current detector 81A provided in branch electrical path 37 . Specifically, in the example of FIG. 1B, a detection device 7 other than the detection device 81 further includes a current detector 7A provided in the first portion 36a. These current detectors help identify a specific power P _grid .

In both the example of FIG. 1A and the example of FIG. 1B, the control device 8 causes the specific power P _grid to follow the constant target power P _grid ^* . 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 this embodiment, the control device 8 is configured to be able to control the power P ₂ generated by the second power generation device 2 as well. Note that the illustrated detection devices 7, 71 and 81 are devices that detect electric power, and therefore can be called power detection devices.

Hereinafter, an example of control of the generated power _P1 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 that the first generated power P ₁ should follow may be referred to as command first generated power P ₁ ^* . A command value that the charge/discharge power P _storage of the power storage device 9 should follow is sometimes referred to as a command charge/discharge power P _storage ^* .

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

In the example according to this description, the control device 8 sets the commanded first power generation 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 generator 3, the operating environment, and the like.

From "start" to "end" in the flowchart of FIG. 5 constitutes one control cycle. The controller 8 can repeatedly perform this control cycle.

In step S<b>1 , a specific power P _grid is input to the control device 8 .

After step S1, the target power P _grid ^* is input to the control device 8 in step S2. Specifically, the target power P _grid ^* is input from the host controller to the controller 8 .

After step S2, in step S3, the controller 8 calculates the differential power P _delta . The differential power P _delta is the difference obtained by subtracting the specific power P _grid from the target power P _grid ^* .

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

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

Here, P ₁ ^* (s−1) indicates P ₁ ^* before being updated in the current control cycle. P ₁ ^* (s) refers to P ₁ ^* after being updated in the current control cycle. The same is true for 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 a 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 greater than zero and the command first generated power P ₁ ^* is greater than the lower limit power P _min . If the second condition is satisfied, in step S7, the control device 8 reduces the command first generated power _P1 ^* by the first step width _Pwidth1 . Using a formula, P ₁ ^* set in step S7 is given by P ₁ ^* (s)=P ₁ ^* (s−1)−P _width1 .

Further, when 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 a 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 . If the third condition is satisfied, in step S9, the control device 8 increases the command first generated power _P1 ^* by the first step size _Pwidth1 . Using a formula, P ₁ ^* set in step S9 is given by P ₁ ^* (s)=P ₁ ^* (s−1)+P _width1 .

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 a 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 greater 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 controller 8 maintains the command first generated power _P1 ^* at the lower limit power _Pmin . Using a formula, P ₁ ^* set in step S11 is given by P ₁ ^* (s)=P _min .

Further, when the fourth condition is established, in step S12, the control device 8 increases the command charge/discharge power P _storage ^* by the second step width P _width2 . Using a formula, 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 less 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 controller 8 maintains the command first generated power _P1 ^* at the upper limit power _Pmax . Using a formula, P ₁ ^* set in step S13 is given by P ₁ ^* (s)=P _max .

Further, when the fifth condition is satisfied, in step S14, the control device 8 reduces the command charge/discharge power P _storage ^* by the second step width P _width2 . Using a formula, 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 S<b>15 , the control device 8 transmits the command first power generation P ₁ ^* to the first power generation device 3 . In step S<b>16 , 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 _P1 ^* and the command charge/discharge power _Pstorage ^* can be updated successively. The first generated power P ₁ of the first power generator 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 manner, 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 a control period _Tp . Specifically, the control cycle consists of updating the commanded first generated power P ₁ ^* in the control device 8, transmitting the commanded first generated power P ₁ ^* from the control device 8 to the first power generation device 3, and 8, and transmission of ^the command charge/discharge power P _storage ^* from the control device 8 to the power storage _device 9. Then, the update of the commanded first generated power P ₁ ^* in the control device 8 is repeated at the control period 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 at the control cycle T _p . The update of the command charge/discharge power P _storage ^* in the control device 8 is repeated at the control period T _p . Transmission of command charge/discharge power P _storage ^* from control device 8 to power storage device 9 is repeated at control cycle 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 ^* of 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 ^* that the first power generator 3 has. The control period _Tp is, for example, 1 millisecond or less, and in one specific example is 100 microseconds or less. Doing so is suitable for controlling the first generated power P ₁ with high responsiveness. Specifically, by doing so, even if the power generated by a power generator different from the first power generator ₃ , such as the second power generation P2, instantaneously fluctuates, In response, the first generated power _P1 can be controlled with high responsiveness, and the total generated power _Psum can be stabilized. Thereby, the electric power received from the commercial power source 5A can be stabilized. This is advantageous from the viewpoint of maintaining a good power supply and 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 longer, and may be 1 microsecond or longer.

In addition, in the present embodiment, the control device 8 updates the command charge/discharge power P _storage ^* of the power storage device 9 at a certain control cycle _Tp . The charge/discharge power P _storage follows the command charge/discharge power P _storage ^* that the power storage device 9 has. Numerical examples of the control period _Tp are as described above.

Hereinafter, the terms first processing, second processing, third processing and fourth processing may be used. The first process is a process of decreasing the first generated power _P1 . The second process is a process of increasing the charge/discharge power P _storage . The third process is a process of increasing the first generated power _P1 . A fourth process is a process of decreasing 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 greater than zero, the control device 8 performs the first process before executing the second process when executing the second process. to run. Further, when the power difference P _delta is smaller than zero and the fourth process is to be executed, the control device 8 executes the third process before executing the fourth process.

As described above, the control device 8 preferentially executes the first process over the second process. Further, the control device 8 preferentially executes the third process over the fourth process. In this way, charging and discharging of the power storage device 9 can be easily suppressed. This makes it possible to use an inexpensive power storage device 9 with a limited capacity. For this reason, preferentially executing the first process or the third process will help realize an inexpensive distributed power supply system 1 suitable for stabilizing the power supplied from the commercial power supply 5A to the load 5B. can contribute. Moreover, suppressing the capacity of the power storage device 9 is advantageous from the viewpoint of miniaturization of the power storage device 9 .

The state in which the power supplied from the commercial power source to the load is stable, as in this embodiment, can be referred to as the "stable load power as viewed from the commercial power source." When the load power "as seen from the commercial power supply" is stable, it is easy to balance power supply and demand, and the voltage of the commercial power supply is less likely to fluctuate.

Specifically, in the present embodiment, the power required by the load 5B is covered by the power from the power output device 6 and the power from the commercial power supply 5A. Since the power storage device 9 can absorb fluctuations in the power _P2 generated by the power generation device 2 using renewable energy, even in situations where such fluctuations occur, the power supplied from the power output device 6 to the load 5B is stabilized. be able to. By stabilizing the power supplied from the power output device 6 to the load 5B, the power supplied from the commercial power supply 5A to the load 5B can also be stabilized. Moreover, as described above, in the present embodiment, the priority of control is appropriately set. Therefore, the effect of stabilizing the electric power supplied from the commercial power supply 5A to the load 5B can be obtained by the inexpensive power storage device 9 whose capacity is suppressed. Therefore, the technique according to the present embodiment can contribute to the realization of an inexpensive distributed power supply system suitable for stabilizing the load power "as seen from the commercial power supply".

Also, the required power of the load 5B may change. Even in such a case, according to the control and power storage device 9, fluctuations in the electric power supplied from the commercial power supply 5A to the load 5B can be easily suppressed.

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

In the example of FIG. 5, in the first process and the third process, the command first generated power P ₁ ^* to be followed by the first generated power P ₁ is changed by the first step width P _width1 at least once. . In the second process and the fourth process, the command charge/discharge power P _storage ^* that the charge/discharge power P _storage should follow is changed by the second step width P _width2 at least once.

The first step width P _width1 and the second step width P _width2 can be set so as to ensure both control responsiveness and stability. 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 commanded first generated power _P1 ^* reaches the lower limit power _Pmin by the first process. When the commanded first generated power _P1 ^* reaches the upper limit power _Pmax by the third process, the fourth process is started. By setting the lower limit power P _min and the upper limit power P _max suitable for the first power generator 3, it is impossible for the first power generator ₃ to adjust the power received from the commercial power supply 5B by adjusting the first generated power P1. It can be executed in a range without

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 commanded first generated power _P1 ^* at the lower limit power _Pmin . The fourth process is performed while maintaining the commanded first power generation 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. Doing so is suitable for suppressing charging and 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 generator 3 can currently output. The lower limit electric power P _min is set, for example, to a value that ensures power generation efficiency in the first power generator 3 .

The upper limit power P _max and the lower limit power P _min may be changed during 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 generated power P ₁ that can be output by the first power generation device 3 is the heating medium supplied to the evaporator 3B 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 temperature detected by 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 temperature detected by the temperature sensor 3D.

The upper limit power P _max and the lower limit power P _min may be kept constant during 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 process in which one of a plurality of processes including a first process, a second process, a third process and a fourth process is selected and executed. Including mode. The 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 . 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 continue. This is suitable for suppressing charging and discharging of the power storage device 9 . According to the operation in which charging/discharging is easily suppressed, it is possible to use an inexpensive power storage device 9 whose capacity is suppressed.

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

The commanded first generated power P ₁ ^* at the start of the first mode may be a value greater than zero and less than the rated value of the first generated power P ₁ and may be between 20% and 80% of the rated value. It may be a value within a range, and may be a value within a range of 40% to 60% of the rated value.

The commanded first generated power P ₁ ^* at the start of _the first mode may be a value greater than the lower limit power P _min and smaller than the upper limit power P _{max .} A value within the range of 20% to 80% of the width may be added to the lower limit power P _min , and a value within the range of 40% to 60% of the width is added to the lower limit power P _min. can be a value.

Typically, after several days have passed since the start of the first mode, periodicity appears in the daily change in the first generated power _P1 . In one specific example, in the first mode, after two days or more have passed since the start of the first mode, the timing at which the first generated power P ₁ increases across the reference power and the first generated power P ₁ exceeds the reference power The transition of the first generated electric power P ₁ that appears within one day with the timing of falling across the lines appears repeatedly over a plurality of days. Here, the reference power is power greater than zero and less than the rated value of the first generated power. The reference power may be a value within a range of 20% to 80% of the rated value, or a value within a range of 40% to 60% of the rated value.

In the present embodiment, the total generated power P _sum is the sum of the generated power P ₁ of the first power generator 3 and the power generated P ₂ of the second power generator 2 . Therefore, in the first mode, when the second generated power _P2 increases, the first generated power _P1 can be decreased. Also, when the second generated power _P2 decreases, the first generated power _P1 can be increased. Thus, in this embodiment, the generated power _P1 can be controlled complementarily with the generated power _P2 .

When the second power generation device 2 is a solar power generation device, the power _P2 generated by the second power generation device 2 fluctuates depending on the weather. However, according to the present embodiment, when the generated power _P2 fluctuates in this manner, the first generated power _P1 can be controlled so as to suppress fluctuations in the total generated power _Psum . Typically, the responsiveness of the control of the generated power _P1 of the first power generation device 3 is higher than the responsiveness of the control of the generated power of the thermal power plant owned by the electric power company. In one specific example, even in a situation where the generated power _P2 drops for a short period of time due to clouds crossing the sun, the first generated power _P1 can be controlled with high responsiveness, and fluctuations in the total generated power _Psum suppressed. This is advantageous from the point of view of stabilizing the specific power P _grid .

If the differential power P _delta does not become zero even after executing the first to fourth processes, the second power generation P ₂ of the second power generator 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, if the difference power P _delta does not become zero even if the first process and the second process are executed, the second power generation P ₂ is reduced. may bring the differential power P _delta closer to zero.

In one example, the first step width P _width1 and the second step width P _width2 are fixed values. By doing so, the control can be easily stabilized.

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, the larger P _delta is, the larger the first step width P _width1 and the second step width P _width2 can be. In this way, both control stability and responsiveness can be achieved. Specifically, it is possible to reduce the number of control cycles that are repeated until the generated power _P1 and the charge/discharge power P _storage converge while ensuring the stability of control. As a result, the generated power _P1 and the charge/discharge power P _storage can be converged in a short time. This is advantageous from the point of view of stabilizing the specific power P _grid .

One of the first step width P _width1 and the second step width P _width2 may be changed according to the magnitude of P _delta . Specifically, one of the first step width P _width1 and the second step width P _width2 may be increased as P _delta increases.

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

FIG. 6A shows a specific example of this embodiment. In the specific example of FIG. 6A, the plurality of power generators 32 are two power generators, the first power generator 3 and the second power generator 2 . The first power generation device 3 is an exhaust heat power generation device that generates power using exhaust heat. The second power generation device 2 is a solar power generation device. The power storage 9A is a storage battery.

In the following description, the power generated by the first power generator 3 may be referred to as exhaust heat power. The power generated by the second power generator 2 may be referred to as photovoltaic power. The required power of the load 5B may be referred to as load power. The power received by the load 5B from the commercial power supply 5A may be simply referred to as received power. As described above, a value that indicates the charging power of the storage battery 9A when positive and indicates the discharging power of the storage battery 9A when the absolute value is negative is sometimes referred to as charging/discharging power. The power output from the power output section 6о of the power output device 6 may be simply referred to as 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 sum of exhaust heat power generation and photovoltaic power generation is smaller than load power in any time zone. During the daytime hours, the photovoltaic power is large, the sum of the waste heat power and the photovoltaic power is maximum, the sum is closest to the load power, and the received power is the minimum. On the other hand, in the night time period, the photovoltaic power is zero, and the received power is maximum when the load power is maximum. In the comparative example of FIG. 6B, the deviation between the maximum value and the minimum value of received power in one day is large.

The comparative example in FIG. 6C differs from the comparative example in FIG. 6B in that there is no exhaust heat power generation device. Moreover, in the comparative example of FIG. 6C, compared with the comparative example of FIG. 6B, photovoltaic power generation power is large. In the comparative example of FIG. 6C, similarly to the comparative example of FIG. 6B, the received power is the minimum during the daytime hours. In the night time zone, the received power is maximum when the load power is maximum. In the comparative example of FIG. 6C, the maximum value of the received power is larger than the comparative example of FIG. 6B, and the difference between the maximum and minimum values of the received power in one day is large.

In the comparative example of FIG. 6D, the photovoltaic power generation power is larger than that of the comparative example of FIG. 6C. Specifically, in the comparative example of FIG. 6D, the amount of power generated in one day by the photovoltaic power generation device is the same as the total amount of power generated in one day by the waste heat power generation device and the photovoltaic power generation device in the comparative example in FIG. 6B. As such, it is assumed that photovoltaic power can be obtained. In the comparative example of FIG. 6D, the maximum value of photovoltaic power is large. At certain times during the daytime hours when this maximum value appears, this maximum value is greater than the received power. Therefore, at this time, the received power is negative, that is, a reverse power flow occurs from the distributed power supply system to the commercial power supply. Also in the comparative example of FIG. 6D, the photovoltaic power is zero and the load power is maximum in the nighttime hours. In the comparative example of FIG. 6D, the deviation between the maximum value and the minimum value of received power in one day is larger than the comparative example of FIG. 6C.

The comparative example shown in FIG. 6E differs from the example shown in FIG. 6A in that there is no waste heat power generation device and that photovoltaic power generation is large as in the comparative example shown in FIG. 6D. In the comparative example of FIG. 6E, the storage battery is charged and discharged, and reverse power flow does not occur. Moreover, in the comparative example of FIG. 6E, unlike the comparative examples of FIGS. 6B to 6D, the received power is substantially constant over one day. However, the photovoltaic power generation is zero in the night time zone, and the photovoltaic power generation power is large in the day time zone. Therefore, the charge/discharge power of the storage battery and the amount of power stored in the storage battery can increase. Therefore, the comparative example of FIG. 6E requires a large-capacity storage battery.

On the other hand, in the specific example of the present embodiment shown in FIG. 6A, the exhaust heat power generation device 3, the photovoltaic power generation device 2, and the storage battery 9A are combined. Further, in this specific example, the control described using 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 keep the received power substantially constant for one day while using the storage battery 9A with a small capacity.

It should be noted that it is not essential for P _grid to follow a constant target power. Even in such a case, it can be said that the above control suppresses fluctuations in P _grid and stabilizes the power supplied from the commercial power source to the load. This disclosure is
a plurality of power generators 32 including the first power generator 3;
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 6? connected to a commercial power source 5A via a branch BP connected to a load 5B. and,
a detection device 71 or 81;
a control device 8;
A value representing the power received from the commercial power supply 5A and specified using the detection device 71 or 81 is defined as the specific power P _grid , and the power generated by the first power generation device 3 is defined as the first power generation P ₁ . When the value indicating the charged power of the power storage device 9 when positive and the value indicating the discharged power of the power storage device 9 when the absolute value is negative is defined as the charged/discharged power P _storage of the power storage device 9, the control The device 8 is
Calculate the differential power P _delta obtained by subtracting the specific power P _grid from the target power P _grid ^* ,
When the differential power P _delta is greater than zero and the second process for increasing the charge/discharge power P _storage is to be performed, the first process for decreasing the first generated power P ₁ is performed before the second process is performed. run,
When the difference power P _delta is smaller than zero, when executing the fourth process of decreasing the charge/discharge power P _storage , the third process of increasing the first generated power P ₁ is performed before executing the fourth process. Execute,
It can also be considered to provide a distributed power supply system 1 . Such a distributed power supply system can be an inexpensive system suitable for stabilizing power supplied to loads from a commercial power supply.

Similarly, the present disclosure
a plurality of power generators 32 including the first power generator 3;
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 6? connected to a commercial power source 5A via a branch BP connected to a load 5B. and,
A control device 8 that controls the detection device 71 or 81 and the distributed power supply system 1 provided,
A value representing the power received from the commercial power supply 5A and specified using the detection device 71 or 81 is defined as the specific power P _grid , and the power generated by the first power generation device 3 is defined as the first power generation P ₁ . When the value indicating the charged power of the power storage device 9 when positive and the value indicating the discharged power of the power storage device 9 when the absolute value is negative is defined as the charged/discharged power P _storage of the power storage device 9, the control The device 8 is
Calculate the differential power P _delta obtained by subtracting the specific power P _grid from the target power P _grid ^* ,
When the differential power P _delta is greater than zero and the second process for increasing the charge/discharge power P _storage is to be performed, the first process for decreasing the first generated power P ₁ is performed before the second process is performed. run,
When the difference power P _delta is smaller than zero, when executing the fourth process of decreasing the charge/discharge power P _storage , the third process of increasing the first generated power P ₁ is performed before executing the fourth process. Execute,
It can also be considered to provide a control device 8 .

Similarly, the present disclosure
a plurality of power generators 32 including the first power generator 3;
a power storage device 9 connected to a plurality of power generation devices 32;
A power input unit 6i connected to a plurality of power generators 32 and a power storage device 9, a power output unit 6? connected to a commercial power supply 5A via a branch BP connected to a load 5B,
A control method for controlling a power output device 6 including a detection device 71 or 81 and a distributed power supply system 1 comprising
A value representing the power received from the commercial power supply 5A and specified using the detection device 71 or 81 is defined as the specific power P _grid , and the power generated by the first power generation device 3 is defined as the first power generation P ₁ . defined as the charge/discharge power P _storage of the power storage device 9, which indicates the charge power of the power storage device 9 when positive and indicates the discharge power of the power storage device 9 when the absolute value is negative,
calculating a differential power P _delta obtained by subtracting the specific power P _grid from the target power P _grid ^* ;
When the differential power P _delta is greater than zero and the second process for increasing the charge/discharge power P _storage is to be performed, the first process for decreasing the first generated power P ₁ is performed before the second process is performed. to perform;
When the difference power P _delta is smaller than zero, when executing the fourth process of decreasing the charge/discharge power P _storage , the third process of increasing the first generated power P ₁ is performed before executing the fourth process. to perform;
It can also be considered to provide a control method including

According to the technology according to the present disclosure, power generated by a power generation device that has power generation adjustment capability, power generated by a power generation device that uses renewable energy, and power received from a commercial power supply are stabilized by a small-capacity power storage device. be able to. Examples of power generators having power generation adjustment capability include power generators that use exhaust heat to generate power and power generators that use fuel cells. Examples of power generators that use renewable energy include power generators that use sunlight and power generators that use wind power.

1 Distributed power supply system 2, 3 Power generation devices 2A, 3R Power generation power sources 2B, 3H, 9B Power converter 3A Pump 3B Evaporator 3C Expander 3D Temperature sensor 3E Bypass valve 3F Condenser 3G Generator 5A Commercial power source 5B Load 6 Electricity Output devices 7, 71, 81 Detection devices 7A, 71A, 81A Current detectors 7B, 71B, 81B Voltage detectors 7C, 71C, 81C Electric power calculation unit 8 Control device 9 Power storage device 9A Power storage devices 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 points

Claims (10)

a plurality of power generators including a first power generator;
a power storage device connected to the plurality of power generation devices;
a power output device including a power input section connected to the plurality of power generation devices and the power storage device, and a power output section connected to a commercial power supply via a branch section to which a load is connected;
a detection device;
a control device that causes the specific power, which is a value representing the power received from the commercial power supply and is specified using the detection device, to follow a constant target power;
The power generated by the first power generation device is defined as the first power generation, and the value indicating the charging power of the power storage device when positive and the absolute value when negative indicates the discharging power of the power storage device When defined as the charge/discharge power of a power storage device, the control device
calculating a differential power obtained by subtracting the specific power from the target power;
When the differential power is greater than zero, when executing the second process of increasing the charge/discharge power, the first process of decreasing the first generated power is executed before executing the second process. ,
When the differential power is smaller than zero, when executing the fourth process of decreasing the charge/discharge power, executing the third process of increasing the first generated power before executing the fourth process. ,
Distributed power system. The control device updates the command first generated power possessed by the first power generation device at a certain control cycle,
The first generated power follows the command first generated power possessed by the first power generator,
The control period is 1 millisecond or less,
The distributed power system of Claim 1. The first power generation device is a thermal power generation device that uses heat to generate power, or a fuel cell power generation device,
3. The distributed power system according to claim 1 or 2. The plurality of power generators includes a second power generator,
The second power generation device is a power generation device that uses renewable energy,
4. The distributed power system according to any one of claims 1-3. The second power generation device is a solar power generation device or a wind power generation device,
5. The distributed power system of claim 4. The control device sets a lower limit power that is the lower limit of the command first generated power that the first generated power should follow, and an upper limit power that is the 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,
The fourth process is started when the command first generated power reaches the upper limit power by the third process.
6. A distributed power system according to any one of claims 1-5. 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,
7. A distributed power system according to any one of claims 1-6. an AC electric line extending from the power output to the commercial power supply and including a first portion between the power output and the branch and a second portion between the branch and the commercial power;
a branch electric circuit extending from the branch portion to the load,
The detection device is
(i) a current detector provided in said second portion, or
(ii) including a current detector provided in said branch circuit;
Distributed power system according to any one of claims 1 to 7. a plurality of power generators including a first power generator;
a power storage device connected to the plurality of power generation devices;
a power output device including a power input section connected to the plurality of power generation devices and the power storage device, and a power output section connected to a commercial power supply via a branch section to which a load is connected;
and a detection device for causing a distributed power supply system to follow a certain target power with a specific power, which is a value representing the power received from the commercial power supply and is specified using the detection device. A controller for controlling,
The power generated by the first power generation device is defined as the first power generation, and the value indicating the charging power of the power storage device when positive and the absolute value when negative indicates the discharging power of the power storage device When defined as the charge/discharge power of a power storage device, the control device
calculating a differential power obtained by subtracting the specific power from the target power;
When the differential power is greater than zero, when executing the second process of increasing the charge/discharge power, the first process of decreasing the first generated power is executed before executing the second process. ,
When the differential power is smaller than zero, when executing the fourth process of decreasing the charge/discharge power, executing the third process of increasing the first generated power before executing the fourth process. ,
Control device. a plurality of power generators including a first power generator;
a power storage device connected to the plurality of power generation devices;
a power output device including a power input section connected to the plurality of power generation devices and the power storage device, and a power output section connected to a commercial power supply via a branch section to which a load is connected;
and a detection device for causing a distributed power supply system to follow a certain target power with a specific power, which is a value representing the power received from the commercial power supply and is specified using the detection device. A control method for controlling,
The power generated by the first power generation device is defined as the first power generation, and the value indicating the charging power of the power storage device when positive and the absolute value when negative indicates the discharging power of the power storage device When defined as the charge/discharge power of a power storage device,
calculating a differential power obtained by subtracting the specific power from the target power;
When the differential power is greater than zero, when executing the second process of increasing the charge/discharge power, the first process of decreasing the first generated power is executed before executing the second process. and
When the differential power is smaller than zero, when executing the fourth process of decreasing the charge/discharge power, executing the third process of increasing the first generated power before executing the fourth process. and
control methods, including;

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