WO2016103628A1

WO2016103628A1 - Decentralized power supply system and power supply control method

Info

Publication number: WO2016103628A1
Application number: PCT/JP2015/006238
Authority: WO
Inventors: 仁吉澤
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2014-12-25
Filing date: 2015-12-15
Publication date: 2016-06-30
Also published as: JP2016123243A

Abstract

A decentralized power supply system (100) is provided with a first power supply (110) and a second power supply (120), the first power supply (110) and the second power supply (120) are connected to a power line (301) to which a load (300) is connected, the first power supply (110) is provided with a first inverter (111), which generates an alternating current voltage, and which outputs, to the power line (301), first power specified by the alternating current voltage, and a power storage device (112) that supplies stored power to the first inverter (111), the second power supply (120) is provided with a second inverter (121), which detects an alternating current voltage via the power line (301), and which outputs, to the power line (301), second power specified by an alternating current synchronized with the alternating current voltage. The first inverter (111) changes, corresponding to a change of an output quantity of the first power, the frequency of the alternating current voltage, and the second inverter (121) changes, corresponding to the frequency change, the output quantity of the second power.

Description

Distributed power supply system and power supply control method

The present invention relates to a distributed power supply system and the like provided with multiple power supplies.

Conventionally, in order to increase the amount of power supply, a distributed power supply system which supplies power from a plurality of power sources has been considered.

For example, Patent Document 1 describes an operation control method of distributed power supply equipment. In this operation control method, an AC voltage source is formed by voltage control operation of the reference inverter. Then, by the current control operation of the remaining inverters, an alternating current source synchronized with the alternating voltage source is formed. Thereby, parallel synchronous operation is performed in the distributed power supply equipment.

Japanese Patent Application Laid-Open No. 11-89096

However, it is not easy to properly share the amount of power output to multiple power supplies.

For example, each of the plurality of power supplies supplies power to the load such that the power supply and demand balances independently of the other power supplies. Thus, the plurality of power supplies can supply power to the load as a whole without excess or deficiency. However, there is a case where the power supply and demand balances in a state where one power source outputs a large amount of power and the other power source outputs little power unintentionally. As a result, the amount of power output may not be properly shared.

Also, for example, the plurality of power sources can appropriately share the amount of power by communicating with each other. However, in this case, it may be expensive and time consuming to prepare equipment and mechanisms to communicate between the power supplies. In addition, the installation location of the power supply may be limited according to the distance that can be communicated by the communication line. In addition, when communication is lost, power supply becomes difficult.

Therefore, an object of the present invention is to provide a distributed power supply system and the like capable of appropriately sharing the output amount of power to a plurality of power sources.

In order to achieve the above object, a distributed power supply system according to an aspect of the present invention includes a first power source and a second power source, and the first power source and the second power source are connected to a load. A first inverter connected to a power line, the first power supply generating an AC voltage, and outputting a first power defined by the AC voltage to the power line; and a stored power for the first inverter And the second power supply detects the AC voltage through the power line, and the second power defined by the first AC current synchronized with the AC voltage is the power line. To the second inverter, the first inverter changing the frequency of the AC voltage according to the change of the first power output amount which is the output amount of the first power, and the second inverter According to the change of Changing the second power output quantity is the output of the second power.

In the power supply control method according to one aspect of the present invention, an alternating voltage is generated in a first power supply connected to a power line to which a load is connected, and the first power defined by the alternating voltage is used as the first power supply. From the second power supply connected to the power line to detect the AC voltage through the power line, and the second power defined by the AC current synchronized with the AC voltage from the second power supply When changing the frequency of the AC voltage according to the change of the first power output amount which is the output amount of the first power when outputting to the power line and outputting the first power, and outputting the second power The second power output amount, which is the output amount of the second power, is changed according to the change of the frequency.

The distributed power supply system and the like according to one aspect of the present invention can appropriately share the output amount of power with respect to a plurality of power supplies.

FIG. 1 is a block diagram showing the configuration of a distributed power supply system according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of a plurality of inverters in the embodiment of the present invention. FIG. 3 is a schematic view showing an example of a power supply state from the inverter to the load. FIG. 4 is a schematic view showing an example (first example) of the power supply state from the two inverters to the load. FIG. 5 is a schematic view showing an example (second example) of the power supply state from the two inverters to the load. FIG. 6 is a schematic view showing an example (third example) of power supply states from two inverters to a load. FIG. 7 is a graph showing an example (first example) of the inverter characteristic according to the embodiment of the present invention. FIG. 8 is a graph showing an example (second example) of the inverter characteristic according to the embodiment of the present invention. FIG. 9 is a graph showing an example (third example) of the inverter characteristic according to the embodiment of the present invention. FIG. 10 is a graph showing an example (fourth example) of the inverter characteristic according to the embodiment of the present invention. FIG. 11 is a graph showing an example (fifth example) of the inverter characteristic according to the embodiment of the present invention. FIG. 12 is a graph showing an example (sixth example) of the inverter characteristic according to the embodiment of the present invention. FIG. 13 is a graph showing an example (seventh example) of the inverter characteristic according to the embodiment of the present invention. FIG. 14 is a flowchart showing the operation of the distributed power supply system according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below all show comprehensive or specific examples. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, order of operations, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. In addition, among the components in the following embodiments, components that are not described in the independent claim indicating the highest concept are described as arbitrary components.

Also, the first, second and third ordinal numbers in the following description may be replaced as appropriate. Also, in the following description, power defined by voltage or current may be expressed as power configured by voltage or current, or may be expressed as power including voltage or current.

Embodiment
The present embodiment shows the configuration of the distributed power supply system including a plurality of power supplies and the operation thereof. First, the configuration of the distributed power supply system will be described using FIGS. 1 and 2.

FIG. 1 is a block diagram showing the configuration of the distributed power supply system according to the present embodiment. The distributed power supply system 100 shown in FIG. 1 is a system for supplying power to the load 300, and comprises

power supplies

110, 120, 130 operating in parallel.

The power supply 110 is a power supply that supplies power to the load 300, and includes an inverter 111 and a power storage device 112. The power supply 120 is a power supply that supplies power to the load 300, and includes an inverter 121 and a power storage device 122. The power supply 130 is a power supply that supplies power to the load 300, and includes an inverter 131. The

power storage devices

112 and 122 are optional components, respectively, and may not be included in the distributed power supply system 100.

The power source 110, the power source 120, and the power source 130 may be expressed as a first power source, a second power source, and a third power source, respectively. The inverter 111, the inverter 121, and the inverter 131 may be expressed as a first inverter, a second inverter, and a third inverter, respectively. The power storage device 112 and the power storage device 122 may be expressed as a first power storage device and a second power storage device, respectively.

In addition, the

generators

210, 220, 230 and the load 300 are electrically connected to the distributed power supply system 100.

Specifically, the generator 210, the power storage device 112, and the inverter 111 are connected to one another via the power line 211. Moreover, the generator 220, the power storage device 122, and the inverter 121 are mutually connected via the power line 221. Further, the generator 230 and the inverter 131 are connected to each other through the power line 231. Further, the

inverters

111, 121, 131 and the load 300 are connected to each other through the power line 301.

Each of the

generators

210, 220, and 230 is a generator that generates direct current power, and is, for example, a solar cell or a fuel cell. Specifically, the generator 210 supplies the generated DC power to one or both of the inverter 111 and the power storage device 112 through the power line 211. Similarly, the generator 220 supplies the generated DC power to one or both of the inverter 121 and the power storage device 122 via the power line 221. The generator 230 supplies the generated DC power to the inverter 131 via the power line 231.

The generator 210 may be included in the distributed power supply system 100 or may be included in the power supply 110. In addition, the generator 220 may be included in the distributed power supply system 100 or may be included in the power supply 120. In addition, the generator 230 may be included in the distributed power supply system 100 or may be included in the power supply 130.

When each of the

generators

210, 220, 230 is a generator utilizing natural energy such as a solar cell or a fuel cell, a distributed power supply system comprising

power supplies

110, 120, 130 operating in parallel. The effect obtained by 100 is great.

The

inverters

111, 121, and 131 are inverters for converting direct current power into alternating current power.

For example, the inverter 111 obtains DC power from the generator 210 and / or the power storage device 112 via the power line 211. The inverter 121 obtains DC power from the generator 220 and / or the power storage device 122 via the power line 221. The inverter 131 obtains DC power from the generator 230 via the power line 231.

Then, the

inverters

111, 121, and 131 respectively generate AC power from DC power and output the generated AC power. The output AC power is supplied to the load 300 via the power line 301.

In particular, the inverter 111 is an inverter (voltage control inverter) that performs voltage control. The inverter 111 generates an AC voltage having a predetermined magnitude as a reference voltage. For example, the inverter 111 generates an alternating voltage of 200 (Vrms) as a reference voltage. Then, the inverter 111 outputs AC power defined by the AC voltage generated as the reference voltage. That is, the inverter 111 outputs the generated AC voltage as AC power.

Further, the frequency of the AC power output from the inverter 111 changes in accordance with the change of the output amount of the AC power output from the inverter 111. That is, the inverter 111 changes the frequency of the AC power in accordance with the change in the output amount of the AC power.

For example, according to the power state of the power line 301, the inverter 111 outputs AC power so that power can be supplied to the load 300 without excess or deficiency. At that time, the inverter 111 determines the frequency in accordance with the output amount of the AC power output from the inverter 111. Then, the inverter 111 changes the frequency of the AC power output from the inverter 111 to the determined frequency.

AC power is basically defined by AC voltage and AC current. Further, since the frequency of the alternating current defining the alternating current power is basically the same as the frequency of the alternating current voltage defining the alternating current power, the frequency of the alternating current and the frequency of the alternating voltage are the frequencies of the alternating current power It may be expressed as

Further, the output amount in the present embodiment may be an output amount of active power. Inverter 111 outputs power including reactive power to maintain the voltage on power line 301. That is, the power output from the inverter 111 includes active power and reactive power. In FIG. 1, the active power output from the inverter 111 is expressed as P1, and the reactive power output from the inverter 111 is expressed as Q1. And the electric power which inverter 111 outputs is expressed as P1 + jQ1. Here, j represents an imaginary unit.

The

inverters

121 and 131 are inverters (current control inverters) that perform current control. The

inverters

121 and 131 each output AC power defined by AC current synchronized with AC voltage by superimposing AC current with a power factor of 1 (100%) on AC voltage generated as a reference voltage. . That is, the

inverters

121 and 131 output an alternating current synchronized with the alternating voltage as alternating current power.

The

inverters

121 and 131 perform synchronous control of alternating voltage. Therefore, the AC voltage defining the AC power output from the

inverters

121 and 131 is equal to the AC voltage defining the AC power output from the inverter 111. Moreover, the power factor at the time of superimposing alternating current is not limited to 1 (100%), and may be a predetermined power factor or more. For example, the power factor at the time of superimposing alternating current may be 0.9 (90%) or more.

Further, the output amount of the AC power output from the inverter 121 changes according to the change of the frequency of the AC power output from the inverter 121. That is, the inverter 121 changes the output amount of AC power in accordance with the change of the frequency of AC power.

For example, the inverter 121 determines the output amount of the AC power output from the inverter 121 according to the frequency of the AC power output from the inverter 111. Then, the inverter 121 outputs AC power with the determined output amount.

Specifically, inverter 121 detects an alternating voltage on power line 301. Then, the inverter 121 determines the output amount according to the frequency of the detected AC voltage. Then, the inverter 121 outputs AC power defined by the AC current synchronized with the detected AC voltage. At this time, the inverter 121 outputs AC power with an output amount determined according to the frequency. That is, the inverter 121 superimposes alternating current on alternating voltage so that an output amount determined according to the frequency can be obtained.

The inverter 131 also operates in the same manner as the inverter 121. Further, as described above, the output amount may be an output amount of active power. The

inverters

121 and 131 each superimpose an alternating current on the alternating voltage with a power factor of 1 (100%), and therefore output active power without outputting reactive power. In FIG. 1, the active power output from the inverter 121 is expressed as P2, and the active power output from the inverter 131 is expressed as P3.

Each of the

power storage devices

112 and 122 is a device for storing power, and is, for example, a storage battery (secondary battery). The

power storage devices

112, 122 may each be capacitors. For example, the power storage device 112 stores the power supplied from the generator 210 and supplies the stored power to the inverter 111. The power storage device 122 also stores the power supplied from the generator 220 and supplies the stored power to the inverter 121.

A charger for charging the power storage device 112 or the power storage device 122 may be included in the distributed power supply system 100. For example, a charger for charging the power storage device 112 may be installed on the power line 211. Alternatively, such a charger may be included in the power storage device 112. Similarly, a charger for charging the power storage device 122 may be installed on the power line 221. Alternatively, such a charger may be included in the power storage device 122.

The power supplies 110 and 120 can stably supply power to the load 300 by including the

power storage devices

112 and 122. In particular, the power supply 110 can operate continuously as a voltage source by providing the power storage device 112.

The load 300 is an apparatus or facility that uses (consumes) power, and is, for example, a home appliance, a home facility, or a factory facility. The load 300 may include a plurality of devices or a plurality of facilities. In particular, the load 300 may be a plurality of devices or a plurality of facilities in a non-electrified area where power is not supplied from a large-scale power plant. That is, the distributed power supply system 100 may supply power to such a non-electrified area load 300.

In FIG. 1, the load 300 is supplied with P + jQ power. P indicates active power, and Q indicates reactive power. P is equal to the sum of the active powers from the power supplies 110, 120, 130. Therefore, P = P1 + P2 + P3 is established. Q is equal to reactive power from the power supply 110. Therefore, Q = Q1 is established. In the load 300, reactive power is not used, and active power is used.

Each of the

power lines

211, 221, 231, and 301 is a passage through which power is transmitted. Each of the

power lines

211, 221, 231, and 301 is not limited to one physical cable, but may be a power line including coupling of a plurality of conductors or a power network. In particular, each of the

power lines

211, 221, 301 is a power line having a branch. Moreover, each of the

power lines

211, 221, 231, and 301 is not limited to wired. The technology of contactless power transfer may be applied to the

power lines

211, 221, 231, and 301.

Although three

power supplies

110, 120 and 130 are shown in FIG. 1, the number of power supplies may not be three. The number of power supplies may be two or four or more. In particular, each of the power supplies 120, 130 may be optional components and not included in the distributed power supply system 100.

FIG. 2 is a block diagram showing the configuration of

inverters

111, 121, 131 shown in FIG. The inverter 111 is an inverter that performs voltage control and operates as a voltage source. Specifically, the inverter 111 includes a control unit 115, a storage unit 116, and a detection unit 117. Each component in the inverter 111 is, for example, an electrical circuit.

The control unit 115 controls the operation of the inverter 111. For example, the control unit 115 generates an alternating voltage and outputs power specified by the alternating voltage. The storage unit 116 stores information. For example, the storage unit 116 stores the relationship between the output amount and the frequency. The detection unit 117 detects the power state of the power line 301.

For example, the detection unit 117 detects the voltage and current of the power line 301. In addition, the detection unit 117 may detect the output amount of the power output from the inverter 111. Furthermore, the detection unit 117 may detect the state of charge (SOC) of the power storage device 112 by communication with the power storage device 112 or the like. The inverter 111 may separately include a power state detection unit that detects the power state of the power line 301 and a charge state detection unit that detects the charge state of the power storage device 112.

Also, for example, the control unit 115 derives the output amount of the AC power output from the inverter 111 based on the detection result of the detection unit 117. Then, the control unit 115 determines the frequency according to the derived output amount. At this time, the control unit 115 refers to the relationship stored in the storage unit 116, and determines the frequency by specifying the frequency associated with the output amount. Then, control unit 115 generates an AC voltage having the determined frequency, and outputs AC power defined by the generated AC voltage.

Thus, the inverter 111 generates a reference voltage and outputs AC power defined by the reference voltage. The inverter 111 also outputs AC power including active power and reactive power. Moreover, the inverter 111 changes the frequency of alternating current power according to the output amount of alternating current power.

The control unit 115 may change the frequency of the AC power output from the inverter 111 according to the output amount of AC power output from the inverter 111, as in the so-called feedback control. Further, regardless of the information in the storage unit 116, the frequency of the AC power may be changed according to the change in the output amount of the AC power by the circuit of the control unit 115.

The inverter 121 is an inverter that performs current control, and superimposes a current on a reference voltage. The inverter 121 includes a control unit 125, a storage unit 126, and a detection unit 127. Similar to the components in the inverter 111, each component in the inverter 121 is, for example, an electrical circuit.

Control unit 125 controls the operation of inverter 121. For example, the control unit 125 outputs the power defined by the alternating current synchronized with the alternating voltage. The storage unit 126 stores information. For example, the storage unit 126 stores the relationship between the output amount and the frequency. Detection unit 127 detects the power state of power line 301.

For example, the detection unit 127 detects the voltage and current of the power line 301. More specifically, detection unit 127 detects the frequency of the AC voltage on power line 301. Furthermore, the detection unit 127 may detect the charge state of the power storage device 122 by communication with the power storage device 122 or the like. The inverter 121 may separately include a power state detection unit that detects the power state of the power line 301 and a charge state detection unit that detects the charge state of the power storage device 122.

Also, for example, the control unit 125 derives the frequency, phase, and amplitude of the AC voltage that is the reference voltage based on the detection result of the detection unit 127. And control part 125 determines the amount of output of exchange electric power which inverter 121 outputs according to a frequency of exchange voltage. At this time, the control unit 125 refers to the relationship stored in the storage unit 126, and determines the output amount by specifying the output amount associated with the frequency.

In addition, the control unit 125 generates an alternating current synchronized with the alternating voltage based on the frequency and phase of the alternating voltage, and outputs alternating current power defined by the generated alternating current. At this time, the control unit 125 outputs AC power having the determined output amount. That is, the control unit 125 superimposes the alternating current on the alternating voltage so that the alternating current power having the determined output amount can be obtained.

Thereby, the inverter 121 superimposes alternating current on the reference voltage with a power factor of 1 (100%). That is, the inverter 121 outputs active power without outputting reactive power. Moreover, the inverter 121 changes the output amount of alternating current power according to the frequency of alternating current power.

Control part 125 may change the amount of output of exchange electric power which inverter 121 outputs according to a frequency of exchange electric power outputted from inverter 121 like so-called feedback control. Further, regardless of the information of the storage unit 126, the output amount of the AC power may be changed according to the change of the frequency of the AC power by the circuit of the control unit 125.

The inverter 131 is an inverter that performs current control, and superimposes a current on a reference voltage. The inverter 131 includes a control unit 135, a storage unit 136, and a detection unit 137. Similar to the components of the inverter 121, each component of the inverter 131 is, for example, an electrical circuit.

Also, each component in inverter 131 operates in the same manner as the corresponding component in inverter 121. However, in the example of FIG. 1, since the power storage device is not included in the power supply 130, the detection unit 137 does not detect the charge state of the power storage device.

The configuration of each of the

inverters

111, 121, and 131 in FIG. 2 is an example, and may be changed as appropriate.

In the configuration shown in FIGS. 1 and 2, the

inverters

111, 121, and 131 operate in parallel, and use frequencies to appropriately share the amount of output of power. If such a configuration is not used, it is difficult to appropriately share the amount of power output. The difficulty in sharing will be described below with reference to FIGS. 3 to 6.

FIG. 3 is a schematic view showing an example of a power supply state from the inverter to the load. The inverter 401 and the load 500 which perform voltage control are shown by FIG. The inverter 401 and the load 500 are connected to each other via a power line. The reference voltage is 200 (Vrms), and the inverter 401 generates an AC voltage of 200 (Vrms). The load 500 has a resistance of 20 (Ω).

In this case, the inverter 401 outputs power defined by the current of 200 (Vrms) / 20 (Ω) = 10 (A). That is, the inverter 401 outputs power (active power) of 10 (A) × 200 (Vrms) = 2 (kW).

In the example of FIG. 3, since one inverter 401 supplies power to the load 500, it is not necessary to share the output amount of power. The inverter 401 can supply appropriate power to the load 500 without sharing the output amount of power.

Each of FIGS. 4 to 6 is a schematic view showing an example of a state of power supply from two inverters to a load. Each of FIGS. 4 to 6 shows an inverter 401 that performs voltage control, an inverter 402 that performs current control, and a load 500. The inverter 401, the inverter 402, and the load 500 are connected to one another via a power line.

Further, as in the example of FIG. 3, the reference voltage is 200 (Vrms), and the inverter 401 generates an AC voltage of 200 (Vrms). The load 500 has a resistance of 20 (Ω).

The inverter 402 superimposes a current on the reference voltage. Thus, the inverter 402 operates in conjunction with the inverter 401 which generates an alternating voltage as a reference voltage.

In this case, the inverter 401 and the inverter 402 output a current of 10 (A) in total. That is, the inverter 401 and the inverter 402 output a total of 2 (kW) of power (active power). Thereby, appropriate power is supplied to the load 500. However, the output amount of power output from the inverter 401 and the output amount of power output from the inverter 402 are not uniquely identified.

For example, in the example of FIG. 4, the magnitude of the current from the inverter 401 is 10 (A), and the magnitude of the current from the inverter 402 is 0 (A). That is, the output amount of power from the inverter 401 is 2 (kW), and the output amount of power from the inverter 402 is 0 (kW).

Further, in the example of FIG. 5, the magnitude of the current from the inverter 401 is 0 (A), and the magnitude of the current from the inverter 402 is 10 (A). That is, the output amount of power from the inverter 401 is 0 (kW), and the output amount of power from the inverter 402 is 2 (kW).

Further, in the example of FIG. 6, the magnitude of the current from the inverter 401 is -10 (A), and the magnitude of the current from the inverter 402 is 20 (A). That is, the output amount of power from the inverter 401 is −2 (kW), and the output amount of power from the inverter 402 is 4 (kW).

Power is supplied to the load 500 without excess or deficiency in any case of FIGS. However, in either case, the output amounts of the

inverters

401 and 402 are biased. As described above, when each of the

inverters

401 and 402 tries to supply balanced power to the load 500, a deviation may occur in the amount of these outputs according to their response performance. That is, it is not easy for the plurality of inverters to appropriately share the output amount of power.

Therefore, the

inverters

111, 121, and 131 shown in FIG. 1 and FIG. 2 appropriately share the output amount of power using frequencies. Next, with reference to FIGS. 7 to 13, a plurality of examples regarding the characteristics (inverter characteristics) of the

inverters

111, 121, 131 will be described.

FIG. 7 is a graph showing an example of the characteristic of the inverter 111 shown in FIG. Specifically, a thick line 601 in FIG. 7 indicates the characteristics of the inverter 111. In the example of FIG. 7, the inverter 111 has a characteristic that the frequency of the AC power is smaller as the output amount of the AC power (active power) is larger. That is, the inverter 111 lowers the frequency when the amount of output increases. Conversely, the inverter 111 raises the frequency when the amount of output decreases. For example, the characteristic shown in FIG.

Here, F indicates a frequency and P indicates an output amount. F ₀ indicates a reference frequency which is a frequency when the output amount is zero. F _L indicates the minimum value in the frequency change range, and F _H indicates the maximum value in the frequency change range. P _G indicates the maximum value in the change range of the output amount, and P _S indicates the minimum value in the change range of the output amount.

In particular, in the example of FIG. 7, F _H = F ₀ and P _S = 0. Therefore, the characteristic shown in FIG. 7 is further expressed by Equation 2.

Specifically, F ₀ = 50.0 (Hz), F _L = 47.5 (Hz), P _G = 2 (kW). Therefore, the relationship between the frequency and the amount of output is expressed by Equation 3. The inverter 111 can derive the frequency from the output amount using Equation 3.

FIG. 8 is a graph showing an example of the common characteristic of the

inverters

121 and 131 shown in FIG. Specifically, a thick line 602 in FIG. 8 indicates the common characteristic of the

inverters

121 and 131. In the example of FIG. 8, the

inverters

121 and 131 have the characteristic that the output amount of the AC power (active power) is larger as the frequency of the AC power is smaller. That is, the

inverters

121 and 131 increase the output amount when the frequency decreases. Conversely, when the frequency rises, the

inverters

121 and 131 reduce the amount of output.

Since the characteristics shown in FIG. 8 are similar to the characteristics shown in FIG. 7, they are expressed in the same manner as Equations 1 to 3. By transforming Equations 1 to 3, Equations 4 to 6 which are equations for deriving the output amount from the frequency can be obtained.

In particular, the

inverters

121 and 131 having the characteristics shown in FIG. 8 can derive the output amount from the frequency using Equation 6.

For example, when the load 300 uses power of 3 (kW), the

inverters

111, 121, 131 operate as follows according to the characteristics shown in FIGS. 7 and 8.

First, in order to supply power to the load 300, the output amount of the power output from the inverter 111 increases from 0 (kW). As the amount of output increases, the frequency of the power output from the inverter 111 decreases from 50 (Hz). As the frequency decreases, the output amount of the power output from the

inverters

121 and 131 increases from 0 (kW).

When the output amount of the power output from the inverter 111 increases to 1 (kW), the frequency decreases to 48.75 (Hz). When the frequency decreases to 48.75 (Hz), the output amount of the power output from each of the

inverters

121 and 131 increases to 1 (kW). That is, when the frequency is 48.75 (Hz), the output amount of the power output from each of the

inverters

111, 121, and 131 is 1 (kW).

Thereby, the usage amount of the power of the load 300 and the output amount of the power output from the

inverters

111, 121, 131 are balanced. Then, the entire output amount is appropriately shared to the

inverters

111, 121, and 131.

The characteristics shown in FIGS. 7 and 8 are examples of the characteristics of the

inverters

111, 121, 131, and the characteristics of the

inverters

111, 121, 131 may be changed as appropriate.

For example, the ratio of the variation of the output to the variation of the frequency in FIG. 7 (the slope of the variation of the frequency relative to the variation of the output), and the variation of the output and the variation of the frequency in FIG. The ratios (slopes of the amount of change of frequency to the amount of change of output amount) are equal to one another. However, the ratio between the change amount of the output amount in the inverter 111 and the change amount of the frequency, and the ratio between the change amount of the output amount in the

inverters

121 and 131 and the change amount of the frequency may be different from each other.

Specifically,

inverters

121 and 131 may have the characteristics shown in FIG. 9 instead of the characteristics shown in FIG.

FIG. 9 is a graph showing an example of common characteristics of the

inverters

121 and 131 shown in FIG. Specifically, a thick line 603 in FIG. 9 indicates the common characteristic of the

inverters

121 and 131. In the example of FIG. 9, the ratio of the change of the output amount to the change of the frequency is smaller than that of the example of FIG. Therefore, the output amount of each of the

inverters

121 and 131 is smaller than the output amount of the inverter 111.

For example, when the load 300 uses a power of 3 (kW), the power consumption of the load 300 and the inverter 111 at a frequency of 48.125 (Hz) according to the characteristics shown in FIG. 7 and FIG. The amount of output of power from 121 and 131 is balanced. Specifically, at a frequency of 48.125 (Hz), the amount of output from the inverter 111 is 1.5 (kW), and the amount of output from each of the

inverters

121 and 131 is 0.75 (kW) .

In the example of FIG. 9, the characteristics of the

inverters

121 and 131 are changed such that the amount of output of each of the

inverters

121 and 131 is smaller than the amount of output of the inverter 111. However, the characteristics of the

inverters

121 and 131 may be changed such that the output amount of each of the

inverters

121 and 131 is larger than the output amount of the inverter 111.

Also, the characteristic of the inverter 111 may be changed such that the output amount of the inverter 111 is smaller than the output amount of each of the

inverters

121 and 131. Also, the characteristic of the inverter 111 may be changed such that the output amount of the inverter 111 is larger than the output amount of each of the

inverters

121 and 131.

Also, the characteristics of the inverter 121 and the characteristics of the inverter 131 may be changed to be different from each other.

FIG. 10 is a graph showing an example of the characteristics of the

inverters

121 and 131 shown in FIG. Specifically, a thick line 604 in FIG. 10 indicates the characteristics of the inverter 121. A thick line 605 in FIG. 10 indicates the characteristics of the inverter 131. At a frequency of 50 (Hz) or more, the characteristics of the inverter 121 and the characteristics of the inverter 131 match each other.

The rate of change of the output amount to the change of frequency in the inverter 121 is smaller than the rate of change of the output amount to the change of frequency in the inverter 131. Therefore, the output amount of the inverter 121 is smaller than the output amount of the inverter 131.

For example, when the load 300 uses power of 3 (kW), the power consumption of the load 300 and the inverter 111 at a frequency of 48.75 (Hz) according to the characteristics shown in FIG. 7 and FIG. The amount of output of power from 121 and 131 is balanced. Specifically, at a frequency of 48.75 (Hz), the output amount of the inverter 111 is 1 (kW), the output amount of the inverter 121 is 0.5 (kW), and the output amount of the inverter 131 is 1 .5 (kW).

When the power source 130 is used rather than the power source 120, charging and discharging of the power storage device 122 are suppressed. Thus, the example of FIG. 10 may be applied such that the power supply 130 is preferentially used. Thereby, charging and discharging of the power storage device 122 may be suppressed, and the progress of the deterioration of the power storage device 122 may be suppressed.

In addition, since the inverter 111 is included in the power supply 110 including the power storage device 112, the characteristics of the inverter 111 may vary according to the charging state of the power storage device 112.

FIG. 11 is a graph showing an example of the characteristic of the inverter 111 shown in FIG. In FIG. 11, a thick line 601 indicating the characteristic shown in FIG. 7 is shown. For example, the inverter 111 changes the ratio of the change of the frequency to the change of the output amount in accordance with the state of charge. Specifically, the inverter 111 changes the ratio of the change of the frequency to the change of the output amount according to the charge state so that the output amount of the inverter 111 becomes smaller as the charge state becomes lower.

In the example of FIG. 11, when the state of charge is low, the characteristic of the inverter 111 fluctuates from the characteristic indicated by the thick line 601 to the characteristic indicated by the alternate long and short dash line 606. That is, when the state of charge is low, the characteristic fluctuates such that the rate of decrease in frequency with respect to the increase in output amount becomes large. As a result, the amount of output from the

inverters

121 and 131 increases. Therefore, the lower the charge state, the smaller the output amount of the inverter 111.

When the state of charge is high, the inverter 111 may change the characteristics so that the rate of decrease in frequency with respect to the increase in output amount is small. Further, the inverter 111 may change the characteristics in multiple stages according to the degree of charge state.

In addition, since the inverter 121 is included in the power supply 120 including the power storage device 122, the characteristics of the inverter 121 may vary according to the charging state of the power storage device 122.

FIG. 12 is a graph showing an example of the characteristic of the inverter 121 shown in FIG. FIG. 12 shows a bold line 602 indicating the characteristics shown in FIG. For example, the inverter 121 changes the ratio of the change of the output amount to the change of the frequency according to the charge state. Specifically, the inverter 121 changes the ratio of the change of the output amount to the change of the frequency according to the charge state so that the output amount of the inverter 121 becomes smaller as the charge state becomes lower.

In the example of FIG. 12, when the state of charge is low, the characteristic of the inverter 121 fluctuates from the characteristic indicated by the thick line 602 to the characteristic indicated by the alternate long and short dash line 607. That is, when the state of charge is low, the characteristic fluctuates such that the rate of increase of the output amount with respect to the decrease in frequency decreases. As a result, the amount of output from the inverter 121 is reduced. Therefore, the lower the charge state, the smaller the output amount of the inverter 121.

When the state of charge is high, the inverter 121 may change the characteristics so that the rate of increase of the output amount with respect to the decrease in frequency is large. Further, the inverter 121 may change the characteristics in multiple stages according to the degree of charge state.

The inverter 121 may be a bidirectional inverter. For example, when the state of charge is low, the inverter 121 may acquire AC power from the power line 301, convert the acquired AC power into DC power, and supply the DC power to the power storage device 122. In this case, the power supply 120 is treated as a load.

FIG. 13 is a graph showing an example of the characteristics of the

inverters

121 and 131 shown in FIG. FIG. 13 shows a bold line 602 indicating the characteristic shown in FIG.

For example, when the load 300 uses a power of 3 (kW), the power consumption of the load 300 and the inverter 111 at a frequency of 48.75 (Hz) according to the characteristics shown in FIG. 7 and FIG. The amount of output of power from 121 and 131 is balanced. Specifically, at a frequency of 48.75 (Hz), the output amount of each of the

inverters

111, 121, and 131 is 1 (kW).

Thereafter, when the state of charge of power storage device 122 becomes lower than the predetermined state of charge, inverter 121 stops the output of AC power to power line 301, and converts AC power obtained from power line 301 into DC power. Thus, DC power is generated from AC power. Then, the inverter 121 outputs the generated DC power to the power line 221 to charge the power storage device 122.

For example, the inverter 121 uses 1 (kW) of power to charge the power storage device 122. In this case, the output amount of the inverter 121 is treated as −1 (kW). Also, the power supply 120 is treated as a load.

The inverter 111 increases the amount of output as the load increases. Furthermore, the inverter 111 reduces the frequency as the amount of output increases. The inverter 131 increases the amount of output as the frequency decreases.

As a result, at the frequency of 47.5 (Hz), the usage of the power of the load 300 and the power supply 120 and the output of the power from the

inverters

111 and 131 are balanced. Specifically, at a frequency of 47.5 (Hz), the output amount of each of the

inverters

111 and 131 is 2 (kW).

The alternate long and short dash line 608 in FIG. 13 represents the change in the output amount of the inverter 121 during charging and the frequency during charging. Thereafter, when the charge state recovers, the inverter 121 again outputs power with an output amount according to the frequency. Then, again, at the frequency of 48.75 (Hz), the usage amount of the power of the load 300 and the output amount of the power from the

inverters

111, 121, 131 are balanced.

Thus, the power supply 120 can switch between an operation of outputting power according to the frequency and an operation of using power as a load.

In the examples of FIGS. 7 and 8, the output amount and the frequency have a proportional relationship. Specifically, a large output amount is associated with a low frequency, and a small output amount is associated with a high frequency. This relationship may be reversed. That is, a large output amount may be associated with a high frequency, and a small output amount may be associated with a low frequency. Also, a large output amount may be associated with the reference frequency. Further, the output amount and the frequency may be associated with each other in a relationship different from the proportional relationship.

Next, a characteristic operation of the distributed power supply system 100 shown in FIG. 1 will be described using a flowchart.

FIG. 14 is a flowchart showing the characteristic operation of the distributed power supply system 100 shown in FIG. First, inverter 111 generates an AC voltage and outputs the first power defined by the AC voltage to power line 301. At that time, the inverter 111 changes the frequency of the AC voltage according to the change of the first power output amount which is the output amount of the first power (S101).

Next, the inverter 121 detects an alternating voltage via the power line 301, and outputs a second power defined by the alternating current synchronized with the alternating voltage to the power line 301. At this time, the inverter 121 changes the second power output amount, which is the output amount of the second power, according to the change of the frequency (S102). The inverter 131 also operates in the same manner as the inverter 121.

Thereby, the distributed power supply system 100 can appropriately share the output amount of power with respect to the power supplies 110, 120, and 130.

Although the distributed power supply system according to the present invention has been described above based on the embodiment, the present invention is not limited to the embodiment. The present invention also includes embodiments obtained by applying variations that will occur to those skilled in the art with respect to the embodiment, and other embodiments realized by arbitrarily combining a plurality of components in the embodiment.

For example, another component may perform the processing that a particular component performs. Further, the order of executing the processing may be changed, or a plurality of processing may be executed in parallel.

Moreover, the present invention can be realized not only as a distributed power supply system but also as a power supply control method including steps (processes) performed by each component constituting the distributed power supply system.

Finally, a basic configuration example of the distributed power supply system 100, a plurality of modified examples, and the like will be shown. These may be combined as appropriate.

(First example)
A distributed power supply system 100 according to an aspect of the present invention includes a power supply 110 and a power supply 120. The power supply 110 and the power supply 120 are connected to the power line 301 to which the load 300 is connected.

The power supply 110 also includes an inverter 111 and a power storage device 112. The inverter 111 generates an AC voltage and outputs the first power defined by the AC voltage to the power line 301. The power storage device 112 supplies the stored power to the inverter 111. The power supply 120 includes an inverter 121. The inverter 121 detects an AC voltage through the power line 301, and outputs, to the power line 301, a second power defined by a first AC current synchronized with the AC voltage.

Further, the inverter 111 changes the frequency of the AC voltage according to the change of the first power output amount which is the output amount of the first power. The inverter 121 changes the second power output amount, which is the output amount of the second power, according to the change of the frequency.

Thereby, the distributed power supply system 100 can appropriately share the output amount of power with respect to the power supplies 110 and 120.

(Second example)
For example, in the distributed power supply system 100 according to the first example, the ratio of the change amount of the first power output amount to the change amount of the frequency and the ratio of the change amount of the second power output amount to the change amount of the frequency are , May be equal to each other.

As a result, the distributed power supply system 100 can share the output amount of power equally to the power supply 110 operating as a voltage source and the power supply 120 different from the power supply 110.

(Third example)
For example, in the distributed power supply system 100 according to the first example, the ratio of the change amount of the first power output amount to the change amount of the frequency and the ratio of the change amount of the second power output amount to the change amount of the frequency are , May be different from each other.

Thus, the distributed power supply system 100 can output power by giving priority to one of the power supply 110 operating as a voltage source and the power supply 120 different from the power supply 110.

(4th example)
For example, the distributed power supply system 100 of the first example, the second example or the third example may include the power supply 130 connected to the power line 301. The power supply 130 may include an inverter 131. Then, the inverter 131 may detect an alternating voltage via the power line 301, and may output, to the power line 301, the third power defined by the second alternating current synchronized with the alternating voltage. Then, the inverter 131 may change the third power output amount, which is the output amount of the third power, according to the change of the frequency.

The ratio between the change amount of the second power output amount and the change amount of the frequency, and the ratio between the change amount of the third power output amount and the change amount of the frequency may be equal to each other.

As a result, the distributed power supply system 100 can share the output amount of power equally to the two

power supplies

120 and 130 different from the power supply 110 operating as a voltage source.

(5th example)
For example, the distributed power supply system 100 of the first example, the second example or the third example may include the power supply 130 connected to the power line 301. The power supply 130 may include an inverter 131. Then, the inverter 131 may detect an alternating voltage via the power line 301, and may output, to the power line 301, the third power defined by the second alternating current synchronized with the alternating voltage. Then, the inverter 131 may change the third power output amount, which is the output amount of the third power, according to the change of the frequency.

The ratio between the change amount of the second power output amount and the change amount of the frequency and the ratio between the change amount of the third power output amount and the change amount of the frequency may be different from each other.

Thus, the distributed power supply system 100 can output power by giving priority to one of the two

power supplies

120 and 130 different from the power supply 110 operating as a voltage source.

(6th example)
For example, in the distributed power supply system 100 according to the first example, the ratio between the change amount of the first power output amount and the change amount of the frequency may change according to the state of charge of the power storage device 112.

Thereby, the distributed power supply system 100 can adjust the amount of output from the power supply 110 according to the charge state of the power storage device 112 included in the power supply 110 operating as a voltage source.

(7th example)
For example, in the distributed power supply system 100 of the first example or the sixth example, the power supply 120 may include the power storage device 122. Then, the power storage device 122 may supply the stored power to the inverter 121. Then, the ratio between the change amount of the second power output amount and the change amount of the frequency may change according to the charge state of the power storage device 122.

Thus, the distributed power supply system 100 can adjust the amount of output from the power source 120 according to the charging state of the power storage device 122 included in the power source 120 different from the power source 110 operating as a voltage source.

(Eighth example)
For example, in the first example distributed power supply system 100, the power supply 120 may include a power storage device 122. The power storage device 122 may supply the stored power to the inverter 121. And inverter 121 may be a bidirectional inverter. Then, when the state of charge of power storage device 122 is lower than the predetermined state of charge, inverter 121 may obtain power from power line 301 and cause power storage device 122 to be charged without outputting the second power. .

Thereby, the distributed power supply system 100 can charge the power storage device 122 according to the charge state of the power storage device 122 included in the power supply 120 different from the power supply 110 operating as a voltage source.

(The 9th example)
In the power supply control method according to one aspect of the present invention, an alternating voltage is generated in the power supply 110 connected to the power line 301 to which the load 300 is connected, and the first power defined by the alternating voltage is transferred from the power supply 110 to the power line 301 It is output (S101). Then, the AC voltage is detected through the power line 301 in the power source 120 connected to the power line 301, and the second power defined by the AC current synchronized with the AC voltage is output from the power source 120 to the power line 301 (S102).

When the first power is output, the frequency of the AC voltage changes according to the change of the first power output amount which is the output amount of the first power. When the second power is output, the second power output amount, which is the output amount of the second power, changes in accordance with the change of the frequency.

As a result, the amount of power output is properly shared with the power supplies 110 and 120.

DESCRIPTION OF SYMBOLS 100 Distributed

power supply system

110, 120, 130

Power supply

111, 121, 131

Inverter

112, 122 Power storage apparatus 300 Load 301 Power line

Claims

The first power supply,
Equipped with a second power supply,
The first power supply and the second power supply are connected to a power line to which a load is connected,
The first power supply is
A first inverter generating an alternating voltage and outputting a first power defined by the alternating voltage to the power line;
A first power storage device for supplying stored power to the first inverter;
The second power supply includes a second inverter that detects the alternating voltage via the power line and outputs a second power defined by a first alternating current synchronized with the alternating voltage to the power line.
The first inverter changes the frequency of the AC voltage according to a change of a first power output amount which is an output amount of the first power,
A distributed power supply system, wherein the second inverter changes a second power output amount, which is an output amount of the second power, according to a change in the frequency.
The dispersion according to claim 1, wherein a ratio of a change amount of the first power output amount to a change amount of the frequency, and a ratio of a change amount of the second power output amount to a change amount of the frequency are equal to each other. Power supply system.
The dispersion according to claim 1, wherein the ratio between the change amount of the first power output amount and the change amount of the frequency, and the ratio between the change amount of the second power output amount and the change amount of the frequency are different from each other. Power supply system.
The distributed power supply system further comprises a third power supply connected to the power line,
The third power supply includes a third inverter that detects the alternating voltage via the power line and outputs a third power defined by a second alternating current synchronized with the alternating voltage to the power line.
The third inverter changes a third power output amount, which is an output amount of the third power, according to the change of the frequency.
The ratio of the change amount of the second power output amount to the change amount of the frequency, and the ratio of the change amount of the third power output amount to the change amount of the frequency are equal to each other. Distributed power supply system according to any one of the preceding claims.
The distributed power supply system further comprises a third power supply connected to the power line,
The third power supply includes a third inverter that detects the alternating voltage via the power line and outputs a third power defined by a second alternating current synchronized with the alternating voltage to the power line.
The third inverter changes a third power output amount, which is an output amount of the third power, according to the change of the frequency.
The ratio of the change amount of the second power output amount to the change amount of the frequency, and the ratio of the change amount of the third power output amount to the change amount of the frequency are different from each other. Distributed power supply system according to any one of the preceding claims.
The distributed power supply system according to claim 1, wherein a ratio of the amount of change of the first power output amount to the amount of change of the frequency fluctuates according to a state of charge of the first power storage device.
The second power supply further includes a second power storage device for supplying stored power to the second inverter,
The distributed power supply system according to claim 1 or 6, wherein a ratio of a change amount of the second power output amount to a change amount of the frequency fluctuates according to a charge state of the second power storage device.
The second power supply further includes a second power storage device for supplying stored power to the second inverter,
The second inverter is a bidirectional inverter,
The second inverter acquires power from the power line without outputting the second power when the state of charge of the second power storage device is lower than a predetermined state of charge, and the second power storage device is used as the second power storage device. The distributed power supply system according to claim 1, wherein the system is charged.
An alternating voltage is generated in a first power supply connected to a power line to which a load is connected, and a first power defined by the alternating voltage is output from the first power supply to the power line,
The second power supply connected to the power line detects the alternating voltage via the power line, and outputs a second power defined by the alternating current synchronized with the alternating voltage from the second power supply to the power line,
When outputting the first power, the frequency of the alternating voltage is changed according to a change of the first power output amount which is an output amount of the first power,
A second power output amount which is an output amount of the second power according to a change of the frequency when the second power is output.