Power supply system, control method and power conditioner

Abstract

To provide a technique that prevents interference between output voltage control in a power generator and output voltage control in a power storage device during the autonomous operation of a decentralized power supply system to allow continuous power supply.SOLUTION: A power supply system includes a first power feeding device and a second power feeding device, and can supply an AC power output from at least one of the first power feeding device and the second power feeding device to a load. The first power feeding device includes an inductor connected, at one end, with the AC power output from the second power feeding device and connected, at the other end, with a connecting point of a path on which the first power feeding device and the load are connected with each other. The second power feeding device performs feedback control of adjusting a voltage value related to one end of the inductor to a control target value. The first power feeding device performs feedback control of adjusting a voltage value related to the other end of the inductor to a control target value to control an output voltage of the AC power supplied from the first power feeding device to the load.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a distributed power system including a plurality of power supply sources with voltage control of output power, and a control method thereof. [Background technology]

[0002] In recent years, distributed power supply systems that include a power generation device such as a photovoltaic power generation device and a storage device such as a storage battery and are operated in connection with a commercial power grid have become widespread. In such a distributed power supply system, for example, when power is not supplied from the commercial power grid due to a power outage, the power generated by the power generation device such as a photovoltaic power generation device and the storage power of the storage battery, which constitute the distributed power supply, are used. However, there are cases where the storage battery cannot be charged if it is fully discharged during a power outage in the grid. Note that the following patent documents are prior art documents that describe technologies related to the technology described in this specification. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-146171 A [Patent Document 2] Japanese Patent Application Publication No. 11-89096 Summary of the Invention [Problem to be solved by the invention]

[0004] In the operation of a distributed power supply system, during independent operation, the power generated by a power generation device such as a solar power generation device is converted to AC power via a power conditioner provided in the power generation device, and is output as driving power for driving a load, and is also input to a power conditioner of the power storage device as charging power for charging a storage battery. When the power generation device cannot obtain sufficient generated power to drive the load, the operation mode of the storage device is switched from a charging mode to a discharging mode, and the stored power of the storage battery is converted to AC power via the power conditioner of the power storage device and supplied to the load.

[0005] However, when switching the operation mode of the power storage device (from charge mode to discharge mode), it is necessary to temporarily stop the operation of the load. This is because there is mutual interference between the output voltage control of the power generation device, which is the power source for driving the load, and the output voltage control of the power storage device in the discharge mode. In terms of power supply from distributed power sources during independent operation, consumers are subject to restrictions such as temporarily stopping the operation of the load when switching the operation mode of the power storage device.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a technology that suppresses interference between the output voltage control of a power generation device and the output voltage control of a power storage device during independent operation of a distributed power system, thereby enabling a continuous power supply. [Means for solving the problem]

[0007] One aspect of the disclosed technique for solving the above problem is to A power supply system including a first power supply device and a second power supply device, capable of supplying AC power output from at least one of the first power supply device and the second power supply device to a load, the first power supply device includes an inductor having one end connected to the AC power output from the second power supply device and the other end connected to a connection point of a path connecting the first power supply device and the load; The second power supply device controls a voltage value associated with one end of the inductor to a control target value. In addition to controlling the feedback, the first power supply device controls an output voltage of AC power supplied from the first power supply device to the load by performing feedback control to set a voltage value related to the other end of the inductor to a control target value; It is characterized by:

[0008] As a result, in the power supply system, the power storage PCS 20a of the power storage device 2, which is a first power supply device, can input AC power generated by the power generation device 3, which is a second power supply device connected to one end side of the inductor L (24), via the connection point 2a. The power storage PCS 20a of the power storage device 2 can perform power storage control processing related to charging and discharging based on the voltage on the output end side of the inductor L (24). The power storage device 2 can discharge the power stored in the storage battery unit 27 using the voltage on the output end side of the inductor L (24) as feedback information so that the voltage (load voltage) on the output end side of the inductor L (24) becomes a control target value. In the power supply system including the power generation device 3 and the power storage device 2, the voltages on both ends of the inductor L (24) can be individually controlled, so that the output voltage control during discharge of the power storage device 2 and the output voltage control of the power generation device 3 do not interfere with each other, and continuous power supply is possible. The power storage device 2 and the power generation device 3 can be operated in parallel.

[0009] In one embodiment of the disclosed technique, the first power supply device may be a power storage device having a storage battery and a first power conditioner connected to the storage battery, and when a charging mode is specified as an operation mode of the power storage device, the first power conditioner converts AC power supplied from the second power supply device to the connection point via the inductor into DC power and charges the storage battery, and when a discharging mode is specified as the operation mode, the first power conditioner converts DC power discharged from the storage battery into AC power and controls an output voltage of the AC power based on a voltage value related to one end of the inductor and a voltage value related to the other end of the inductor. This allows the storage PCS 20a, which is the first power conditioner of the power storage device 2, to discharge the power stored in the storage battery unit 27 using the voltage on the input end side of the inductor L (24) as feedback information so that the voltage (load voltage) on the output end side of the inductor L (24) becomes a control target value. In the power supply system, during independent operation, when the power storage device 2 is switched from a charging mode to a discharging mode, continuous power supply is possible without temporarily stopping the operation of the load.

[0010] In one embodiment of the disclosed technology, the first power conditioner may include a first control unit that generates a current reference value from the deviation between the voltage value of the AC power output to the other end of the inductor and an output voltage command value, and a second control unit that performs tracking control with a feedback amount based on the voltage value related to one end of the inductor and the output voltage value of the AC power supplied to the load as a control variable, a voltage value of the AC power output to the other end of the inductor as a manipulated variable, and the current reference value as a target value. In the storage PCS 20a, the voltage on the input end side and the voltage on the output end side of the inductor L (24) are fed back to the control target value to control the current amount of the AC power output from the PCS. By using the discharge mode of the storage PCS 20a in combination during independent operation, it is possible to use power up to the rated capacity of the storage PCS 20a.

[0011] In one embodiment of the disclosed technique, the second power supply device may be a power generation device having a photovoltaic power generation module and a second power conditioner connected to the photovoltaic power generation module, and the second power conditioner may convert DC power generated by the photovoltaic power generation module into AC power based on a control command related to maximum power point tracking control or DC voltage control for keeping the DC voltage input from the photovoltaic power generation module constant at a predetermined value, and output the AC power to one end of the inductor. The PV-PCS 30a, which is a converter, can control the DC / DC converter 32 to operate at the maximum power (value of current x voltage) point at which the power output of the photovoltaic power generation module 37 is maximized or at the optimal operating point, based on the voltage value on the input end side of the inductor L (24) and a control command related to maximum power point tracking control.

[0012] In addition, another aspect of the disclosed technology is A control method for a power supply system including a first power supply device and a second power supply device, capable of supplying AC power output from at least one of the first power supply device and the second power supply device to a load, comprising: the first power supply device includes an inductor having one end connected to the AC power output from the second power supply device and the other end connected to a connection point of a path connecting the first power supply device and the load; The second power supply device executes feedback control to set a voltage value related to one end of the inductor to a control target value; causing the first power supply device to execute feedback control so as to set a voltage value related to the other end of the inductor to a control target value, thereby controlling an output voltage of AC power supplied from the first power supply device to the load; Make the following happen.

[0013] Even in such a configuration, in the power supply system, the power storage PCS 20a of the power storage device 2, which is the first power supply device, can input AC power generated by the power generation device 3, which is the second power supply device connected to one end side of the inductor L (24), via the connection point 2a. The power storage PCS 20a of the power storage device 2 can perform power storage control processing related to charging and discharging based on the voltage on the output end side of the inductor L (24). The power storage device 2 can discharge the power stored in the storage battery unit 27 using the voltage on the output end side of the inductor L (24) as feedback information so that the voltage (load voltage) on the output end side of the inductor L (24) becomes a control target value. In the power supply system including the power generation device 3 and the power storage device 2, the voltages on both ends of the inductor L (24) can be individually controlled, so that the output voltage control during discharge of the power storage device 2 and the output voltage control in the power generation device 3 do not interfere with each other, and continuous power supply is possible. The power storage device 2 and the power generation device 3 can be operated in parallel.

[0014] In addition, another aspect of the disclosed technology is A power conditioner of a power supply system including a first power supply device and a second power supply device, capable of supplying AC power output from at least one of the first power supply device and the second power supply device to a load, The power conditioner comprises: an inductor having one end connected to the AC power output from the second power supply device and the other end connected to a connection point of a path connecting the first power supply device and the load; The second power supply device performs feedback control to set a voltage value related to one end of the inductor to a control target value, and the first power supply device controls an output voltage of AC power supplied from the first power supply device to the load by performing feedback control to set a voltage value related to the other end of the inductor to a control target value; It is characterized by:

[0015] Even in this configuration, in the power supply system, the power conditioner can input AC power generated by the power generation device 3, which is a second power supply device connected to one end side of the inductor L (24), via the connection point 2a. Then, the storage device 2, which is the second power supply device, calculates the power supply voltage based on the voltage on the output end side of the inductor L (24). By using the feedback information, the storage device 2 can perform storage control processing related to charging and discharging. In the storage device 2, the voltage on the output end side of the inductor L (24) is used as feedback information, and the power stored in the storage battery unit 27 can be discharged so that the voltage on the output end side of the inductor L (24) (load voltage) becomes a control target value. In a power supply system including the power generation device 3 and the storage device 2, the voltages on both ends of the inductor L (24) can be controlled individually, so that the output voltage control during discharge of the storage device 2 and the output voltage control of the power generation device 3 do not interfere with each other, and continuous power supply is possible. Parallel operation of the storage device 2 and the power generation device 3 is possible. Effect of the Invention

[0016] According to the present invention, interference between the output voltage control of the power generation device and the output voltage control of the power storage device during independent operation of a distributed power system is suppressed, enabling a continuous power supply. [Brief description of the drawings]

[0017] [Figure 1] 1 is a block diagram showing a schematic configuration of a distributed power supply system to which the present invention is applicable; [Diagram 2] FIG. 1 is an explanatory diagram illustrating the flow of power during independent operation of a distributed power system to which the present invention is applicable. [Diagram 3] FIG. 1 is an explanatory diagram illustrating an outline of the configuration of a distributed power supply system according to a first embodiment of the present invention. [Figure 4] 2 is a diagram illustrating an example of a hardware configuration of a control unit of the power storage PCS according to the first embodiment of the present invention. FIG. [Diagram 5] 2 is a functional block diagram showing an example of a control process of the power storage PCS according to the first embodiment of the present invention. FIG. [Figure 6] FIG. 4 is a diagram showing a simulation result of the control process according to the first embodiment of the present invention. [Figure 7] FIG. 4 is a diagram showing a simulation result of the control process according to the first embodiment of the present invention. [Figure 8] FIG. 4 is a diagram showing a simulation result of the control process according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] [Application example] Hereinafter, application examples of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing a schematic configuration of a distributed power system 1 to which the present invention is applicable. The distributed power system 1 illustrated in Fig. 1 is a hybrid power system including a power storage device 2 and a power generation device 3. The distributed power system 1 constitutes a power supply system that is interconnected with a commercial power system 80 provided on the premises of a consumer and supplies AC power to a load 50 and the interconnected power system 80. The power system 80 and a distribution board 82 are connected via a power line 83, and the load 50 is connected via the distribution board 82. A power meter 81 (ammeter, voltmeter) is provided between the power storage device 2 and the distribution board 82 that constitute the distributed power system 1.

[0019] In the distributed power supply system 1, the power storage device 2 includes a storage battery unit 27 and a power conditioner (hereinafter also referred to as "PCS") 20. The PCS 20 (hereinafter also referred to as "power storage PCS 20") includes a control unit 21, a bidirectional DC / DC converter 22, and a power conversion unit 23. The bidirectional DC / DC converter 22 is connected to the storage battery unit 27. The power generation device 3 includes a photovoltaic power generation module 37 and a power conditioner (PCS) 30. The PCS 30 (hereinafter also referred to as "PV-PCS 30") includes a control unit 31, a DC / DC converter 32, and a power conversion unit 33. The DC / DC converter 32 is connected to the photovoltaic power generation module 37.

[0020] The storage PCS 20 receives the outputs of various sensors including a power sensor 28 (current sensor, voltage sensor) and a power meter 81 provided between the storage battery unit 27 and the bidirectional DC / DC converter 22, and performs control processing related to charging and discharging based on the load conditions detected through the various sensors and a preset mode related to charging and discharging. For example, when discharging, the power discharged from the storage battery unit 27 is voltage-converted via the bidirectional DC / DC converter 22, and the DC power after the voltage conversion is converted into AC power synchronized with the power grid 80 and output from the power conversion unit 23. When discharging is stopped, the discharge from the storage battery unit 27 is stopped, and the AC power output from the power conversion unit 23 based on the discharged power is stopped. Furthermore, when it is determined to charge based on the above mode, load conditions, the charging state of the storage battery unit 27, and the like, the AC power supplied to the connection point 2a through the power grid 80 and the PV-PCS 30 is converted and charged to the storage battery unit 27.

[0021] The PV-PCS 30 receives as input the outputs of various sensors including a power sensor 38 (current sensor, voltage sensor) and a power meter 81 provided between the photovoltaic power generation module 37 and the DC / DC converter 32. Based on information detected through the various sensors, the PV-PCS 30 performs maximum power point tracking (MPPT) control so that the DC / DC converter 32 operates at the maximum power (value of current x voltage) point at which the power generation output of the photovoltaic power generation module 37 is maximized or at an optimal operating point, or performs control to keep the input voltage from the photovoltaic power generation module 37 at a certain constant value.

[0022] In the distributed power system 1 to which the present invention is applied, as shown in Fig. 2, when AC power input from the PV-PCS 30 is obtained, if both the storage PCS 20 and the PV-PCS 30 control the load voltage supplied to the load, their controls will interfere with each other, so the control process related to charging and discharging is switched to the charging mode to operate the storage device 2. In the storage PCS 20, for example, current control is performed with the independent output from the PV-PCS 30 connected to the connection point 2a as charging power, and the storage battery unit 27 is charged via the power conversion section (INV) 33 and the bidirectional DC / DC converter 22. In addition, from the storage PCS 20 in the charging mode, the independent input of the PV-PCS 30 connected to the connection point 2a is output as specific load power for the load in the consumer's facility.

[0023] Incidentally, the power generation device 3 constituting the distributed power system 1 has a rated capacity that is specified in advance by specifications, etc. For example, when the rated capacity of the power generation device 3 is 1.5 KVA, the specific load power that can be additionally supplied during independent operation is limited to 1.5 KVA or less. For example, when the load capacity in the consumer's facility is 1.8 KVA, the use of the load equipment is limited so as not to exceed the rated capacity of 1.5 KVA that the power generation device 3 can supply. Even if the load is used under the restriction, it is difficult to respond to a temporary fluctuation in load capacity that exceeds 1.5 KVA. When the storage device 2 has a specification that exceeds the rated capacity of the power generation device 3 (for example, 2.0 KVA), the control process related to the charging and discharging of the storage PCS 30 is switched to a discharge mode, and the specific load power can be supplied to the load in the consumer's facility. However, since the output voltage control of the PV-PCS 30 and the output voltage control of the storage PCS 30 interfere with each other, it is necessary to temporarily stop the operation of the load.

[0024] As shown in FIG. 3, in a distributed power system 1 according to an application example of the present invention, the power storage PCS 20a of the power storage device 2 includes an inductor L (24). The independent output output from the PV-PCS 30a is input through the inductor L. One end of the inductor L (24) is connected to the independent output of the power conversion unit (INV) 33 of the PV-PCS 30a via an independent input terminal 2b, and the other end is connected to the connection point 2a. Due to the electromagnetic characteristics of the inductor L (24), the inductor L functions as a buffer for the independent output output from the PV-PCS 30a, making it possible to perform voltage control individually at both ends of the inductor L. become.

[0025] Specifically, as shown in Fig. 3 to Fig. 7, the PV-PCS 30a of the power generation device 3 performs voltage control on the input end side where the independent output of the PCS is input to the power storage PCS 30a, based on sensor information detected by a power sensor 25 provided on the input end side of the inductor L (24). The power storage PCS 20a of the power storage device 2 performs load voltage control of the specific load power supplied to the load in the consumer, based on sensor information detected at the connection point 2a on the other end side of the inductor L (24). The power storage PCS 20a uses the current and voltage detected at the connection point 2a on the other end side of the inductor L (24) as feedback information, and controls the bidirectional DC / DC converter 22 and the power conversion unit 23 so that the power value (current value, voltage value) detected by the power meter 81 becomes the control target value.

[0026] In the distributed power supply system 1 according to this application example, during independent operation, the PV-PCS 30a performs feedback control so that the voltage on the input end side of the inductor L (24) becomes a control target value, and the power generated by the photovoltaic power generation module 37 can be converted into AC power and output. Then, in the discharge mode, the power storage PCS 20a performs feedback control so that the voltage (load voltage) on the output end side of the inductor L (24) becomes a control target value, and the power stored in the storage battery unit 27 can be discharged. According to the distributed power supply system 1 according to this application example, since the voltages on both ends of the inductor L (24) can be individually controlled, the output voltage control during the discharge of the storage device 2 and the output voltage control of the power generation device 3 do not interfere with each other. In this application example, when the storage device 2 is switched from the charge mode to the discharge mode during independent operation, continuous power supply is possible without temporarily stopping the operation of the load. In addition, the storage device 2 and the power generation device 3 can be operated in parallel.

[0027] Example 1 Hereinafter, specific embodiments of the present invention will be described in more detail with reference to the drawings.

[0028] <System configuration> Fig. 1 is a block diagram showing a schematic configuration of a distributed power system 1 to which the present invention is applied. The distributed power system 1 in Fig. 1 is a hybrid power system including a power storage device 2 and a power generation device 3. As shown in Fig. 1, the distributed power system 1 constitutes a power supply system that is connected to a commercial power system 80 provided on the premises of a consumer and supplies AC power to a load 50 and the connected power system 80. In the distributed power system 1, the power system 80 and a distribution board 82 are connected via a power line 83, and the load 50 is connected via the distribution board 82. A power meter 81 (ammeter, voltmeter) is provided between the power storage device 2 and the distribution board 82 that constitute the distributed power system 1.

[0029] In the distributed power supply system 1 of FIG. 1, the power storage device 2 includes a storage battery unit 27 and a power conditioner (hereinafter, also referred to as "PCS") 20. The PCS 20 includes a control unit 21, a bidirectional DC / DC converter 22, and a power conversion unit 23. The bidirectional DC / DC converter 22 is connected to the storage battery unit 27. The storage battery unit 27 is a storage battery that stores a predetermined capacity of power determined by a rating or the like, and the number of times of charging and discharging is limited by the rating or the like. The power generation device 3 includes a solar power generation module 37 and a power conditioner (PCS) 30. The PCS 30 includes a control unit 31, a DC / DC converter 32, and a power conversion unit 33. The DC / DC converter 32 is connected to the solar power generation module 37. The solar power generation module 37 is a power generation mechanism that uses sunlight as an energy source. The output (AC power) from the power conversion unit 33 of the PCS 30 is input to the PCS 20 and connected to the connection point 2a via wiring in the PCS 20. In the following, the PCS 20 of the power storage device 2 is also referred to as the "power storage PCS 20," and the PCS 30 of the power generation device 3 is also referred to as the "PV-PCS 30." In this embodiment, a solar power generation system is used as the power generation device, but other power generation systems besides solar power generation can be used in the distributed power system 1 to which the present invention is applied. Examples of other power generation systems include a power generation system using natural energy such as wind power or hydraulic power, and a private power generation system using fuel.

[0030] In the storage PCS 20, the bidirectional DC / DC converter 22 and the power conversion unit 23 are connected by a predetermined bus (DC bus). The bidirectional DC / DC converter 22 is a unit that bidirectionally converts the voltage of the discharge power discharged from the storage battery unit 27 and the voltage of the charging power supplied from the power conversion unit 23 to the storage battery unit 27. The power conversion unit 23 is configured to include an AC / DC converter that converts the AC power supplied from the power system 80 through the connection point 2a or the AC power output from the PV-PCS 30 to the connection point 2a into DC power and outputs it to a predetermined bus, and a DC / AC converter that converts the DC power output to the predetermined bus into AC power synchronized with the power system 80. The storage battery unit 27 and the bidirectional DC / DC converter 22 are equipped with a microcomputer and the like that operate upon receiving a control command from the control unit 21.

[0031] The control unit 21 is a unit including a processor (CPU, etc.), a memory, a gate driver, a communication interface circuit, etc. The control unit 21 receives the outputs of various sensors including a power sensor 28 (current sensor, voltage sensor) and a power meter 81 provided between the storage battery unit 27 and the bidirectional DC / DC converter 22. The control unit 21 performs a control process related to charging and discharging (also referred to as a power storage control process) based on the load status detected through the various sensors including the power sensor 28 and the power meter 81, a preset mode related to charging and discharging, etc. For example, when discharging, the control unit 21 performs a control such that the power discharged from the storage battery unit 27 is voltage-converted via the bidirectional DC / DC converter 22, and the DC power after the voltage conversion is converted into AC power synchronized with the power system 80 and output from the power conversion unit 23. When discharging is stopped, the control unit 21 stops discharging from the storage battery unit 27 and stops the AC power output from the power conversion unit 23 based on the discharged power. Furthermore, when the control unit 21 determines to perform charging based on the above mode, load conditions, the charging state of the storage battery unit 27, etc., it controls so as to convert the AC power supplied to the connection point 2a via the power system 80 and the PV-PCS 30 and charge the storage battery unit 27. Upon receiving a control command from the control unit 21 regarding the above-mentioned power storage control process, the operations of the storage battery unit 27, the bidirectional DC / DC converter 22, and the power conversion unit 23 are controlled.

[0032] In the PV-PCS 30, the DC / DC converter 32 and the power conversion unit 33 are connected by a predetermined bus (DC bus). The DC / DC converter 32 is a unit that converts (boosts) the voltage of DC power generated by the photovoltaic power generation module 37 and supplies it to the predetermined bus. The power conversion unit 32 is a unit that includes a DC / AC converter that converts the DC power supplied from the DC / DC converter 32 to the predetermined bus into AC power synchronized with the power system 80. The DC / DC converter 32 and the power conversion unit 33 incorporate a microcomputer and the like that operates upon receiving a control command from the control unit 31.

[0033] The control unit 31 of the PV-PCS 30 is a unit including a processor (CPU, etc.), a memory, a gate driver, a communication interface circuit, etc. The control unit 31 receives the outputs of various sensors including a power sensor 38 (current sensor, voltage sensor) and a power meter 81 provided between the photovoltaic power generation module 37 and the DC / DC converter 32. Based on information detected through the various sensors including the power sensor 38 and the power meter 81, the control unit 31 performs maximum power point tracking control (MPPT) so that the DC / DC converter 32 operates at the maximum power (value of current x voltage) point where the power output of the photovoltaic power generation module 37 is maximized or at an optimal operating point, or performs control to keep the input voltage from the photovoltaic power generation module 37 at a certain constant value.

[0034] 2 is an explanatory diagram illustrating the flow of power during independent operation of the distributed power system 1. In the distributed power system 1, during independent operation, as shown by the hatched arrows, power generated by the photovoltaic power generation module 37 is converted into AC power via the DC / DC converter 32 and power conversion unit (INV) 33 of the PV-PCS 30, and input to the power storage PCS 20 (independent input). The AC power output from the power conversion unit (INV) 33 (independent output) is connected to the connection point 2a via wiring in the power storage PCS 20.

[0035] In the storage PCS 30, when AC power input from the PV-PCS 30 is obtained, the control process related to charging and discharging is switched to the charging mode to operate the storage device 2. As already explained, if both the storage PCS 20 and the PV-PCS 30 control the load voltage supplied to the load, their mutual controls will interfere with each other. In the storage PCS 20 in the charging mode, current control is performed with the independent output from the PV-PCS 30 conducted to the connection point 2a as charging power, and the storage battery unit 27 is charged via the power conversion unit (INV) 33 and the bidirectional DC / DC converter 22. In the storage PCS 20 in the charging mode, the independent input of the PV-PCS 30 conducted to the connection point 2a is output as a specific load power for the load in the consumer's facility.

[0036] Incidentally, the power generating equipment 3 constituting the distributed power system 1 has a rated capacity that is specified in advance in specifications, etc. For example, if the rated capacity of the power generating equipment 3 is 1.5 KVA, the specific load power that can be additionally supplied during independent operation is limited to 1.5 KVA or less. For example, if the load capacity in the consumer's facility is 1.8 KVA, the use of the load equipment is limited so as not to exceed the rated capacity of 1.5 KVA that the power generating equipment 3 can supply. Even if the load is used under the limited capacity, it is difficult to respond to a temporary fluctuation in load capacity that exceeds 1.5 KVA. In addition, the amount of power generated by the power generating equipment 3 may decrease due to the influence of weather, etc. (power generation based on natural energy such as solar, wind, hydroelectric, and geothermal). When the specifications of the storage device 2 exceed the rated capacity of the power generation device 3 (for example, 2.0 KVA), the control process for charging and discharging the storage PCS 30 can be switched to discharge mode, making it possible to supply specific load power to the consumer's load; however, since the output voltage control of the PV-PCS 30 and the output voltage control of the storage PCS 30 interfere with each other, it was necessary to temporarily stop the operation of the load.

[0037] 3 is an explanatory diagram for explaining the outline of the configuration of a distributed power system 1 according to this embodiment. The power storage PCS 20a of the power storage device 2 of the distributed power system 1 according to this embodiment includes an inductor L (24), and the independent output output from the PV-PCS 30a is input via the inductor L through the independent input terminal 2b. The independent output of the power conversion unit (INV) 33 of the PV-PCS 30a is connected to one end of the inductor L (24), and the connection point 2a is connected to the other end. Due to the electromagnetic characteristics of the inductor L (24), the inductor L functions as a buffer for the independent output output from the PV-PCS 30a, making it possible to perform voltage control at both ends of the inductor L individually.

[0038] Specifically, the storage PCS 20a of the storage device 2 of the distributed power system 1 according to this embodiment includes a power sensor 25 (current sensor, voltage sensor) on one end side to which the independent output output from the PV-PCS 30a of the inductor L (24) is input. Information detected by the power sensor 25 is input to the control unit 21a of the storage PCS 20a and the control unit 31a of the PV-PCS 30a. The PV-PCS 30a of the power generation device 3 performs voltage control on the independent input end side of the storage PCS 30a based on the sensor information detected by the power sensor 25. The control unit 31a of the PV-PCS 30a converts the information detected by the power meter 81 into the sensor information detected by the power sensor 25, and performs maximum power point tracking control so that the photovoltaic power generation module 37 operates at the maximum power (value of current x voltage) point at which the power generation output is maximum, or performs DC voltage control so that the DC / DC converter 32 operates at the optimal operating point. This DC voltage The control refers to a control for maintaining the input voltage from the photovoltaic power generation module 37 at a certain constant value.

[0039] The power storage PCS 20a of the power storage device 2 performs load voltage control of the specific load power supplied to the load in the consumer based on the sensor information detected by the power sensor 25. The power storage PCS 20a control unit 21a performs power storage control processing related to charging and discharging based on the sensor information detected by the power sensor 25, the load status detected through various sensors such as the power sensor 28 and the power meter 81, and a preset mode related to charging and discharging. The control processing will be described later with reference to FIG. 5.

[0040] In the distributed power system 1 according to the present embodiment, the power storage PCS 20a includes an inductor L (24), and the independent output from the PV-PCS 30a can be connected to the connection point 2a through the inductor L. Therefore, in the distributed power system 1, it is possible to individually control the voltages at both ends of the inductor L (24). During independent operation, the PV-PCS 30a of the distributed power system 1 can convert the power generated by the photovoltaic power generation module 37 into AC power and output it (independent output) with the voltage on the input end side of the inductor L (24) as a control target value. In addition, the power storage PCS 20a can perform power storage control processing related to charging and discharging based on the voltage on the output end side of the inductor L (24). When discharging, the power storage PCS 20a can discharge the power stored in the storage battery unit 27 using the voltage on the output end side of the inductor L (24) as feedback information so that the voltage (load voltage) on the output end side of the inductor L (24) becomes the control target value. According to the distributed power system 1 of this embodiment, the voltages across the inductor L (24) can be controlled individually, so there is no interference between the output voltage control during discharging of the power storage device 2 and the output voltage control of the power generation device 3. In this embodiment, when switching from the charge mode to the discharge mode of the power storage device 2 during independent operation, continuous power supply is possible without temporarily stopping the operation of the load. Also, parallel operation of the power storage device 2 and the power generation device 3 is possible.

[0041] <Control unit configuration> FIG. 4 is a diagram showing an example of a hardware configuration of the control unit 21a of the power storage PCS 20a according to the present embodiment. As shown in FIG. 4, the control unit 21a is a computer including a processor 101, a main storage device 102, an auxiliary storage device 103, a communication IF 104, and an input / output IF 105, which are connected to each other by a connection bus 106. The main storage device 102 and the auxiliary storage device 103 are recording media that can be read by the control unit 21a. Each of the above components may be provided in a plurality of units, or some of the components may not be provided. Note that the microcomputers provided in the storage battery unit 27, the bidirectional DC / DC converter 22, the control unit 31a of the PV-PCS 30a, and the DC / DC converter 32 are realized by a hardware configuration substantially equivalent to that of the control unit 21a.

[0042] The processor 101 is a central processing unit that controls the entire control unit 21a. The processor 101 is, for example, a central processing unit (CPU), a micro-processing unit (MPU), a digital signal processor (DSP), or the like. The processor 101, for example, deploys a program stored in the auxiliary storage device 103 in an executable manner in a working area of ​​the main storage device 102, and provides a function that meets a predetermined purpose by controlling peripheral devices through the execution of the program. However, some or all of the functions provided by the processor 101 may be provided by an application specific integrated circuit (ASIC), a graphics processing unit (GPU), or the like. Similarly, some or all of the functions may be realized by a field-programmable gate array (FPGA), a dedicated large scale integration (LSI) such as a numerical calculation processor, or other hardware circuits.

[0043] The main storage device 102 and the auxiliary storage device 103 constitute the memory of the control unit 21a. The storage device 102 stores the programs executed by the processor 101, data processed by the processor, etc. The main storage device 102 includes a flash memory, a RAM (Random Access Memory), and a ROM (Read Only Memory). The auxiliary storage device 103 is a storage medium that stores the programs executed by the processor 101, etc., and operation setting information, etc. The auxiliary storage device 103 is, for example, a hard-disk drive (HDD), a solid-state drive (SSD), an EPROM (Erasable Programmable ROM), a flash memory, a USB memory, a S D (Secure Digital) memory cards and the like. The communication IF104 is a communication interface with a communication network. The communication IF104 can adopt an appropriate configuration according to the connection method with the communication network to be connected. In this embodiment, various control commands are notified between the bidirectional DC / DC converter 22 and the storage battery unit 27 connected via the communication IF104. In addition, the control unit 31a notifies various control commands between the DC / DC converter 32 and the storage PCS 32. The input / output IF105 is an interface for inputting and outputting data between the input device and the output device provided in the power storage PCS 21a. Through the input / output IF105, data is output to a display device such as an LCD or an output device such as a printer connected to the power storage PCS 21a. Also, through the input / output IF105, an operation instruction is accepted, and a process intended by an operator is performed based on the operation instruction. Furthermore, in this embodiment, output signals of various sensors including the power sensor 25 (current sensor, voltage sensor), the power sensor 28, and the power meter 81 connected via the input / output IF105 are input to the control unit 21a. Furthermore, output signals from various sensors including the power sensor 25 (current sensor, voltage sensor) and the power sensor 37 connected via the input / output IF 105 are input to the control unit 31a.

[0044] <Processing flow> FIG. 5 is a functional block diagram showing an example of a control process during discharge executed by the storage PCS 20a according to this embodiment. The control process shown in FIG. 5 is provided, for example, by cooperation between the control unit 21a and the power conversion unit (INV) 23 of the storage PCS 20a. During discharge of the storage PCS 20a according to this embodiment, feedback control is performed by the control process shown in FIG. 5 so that the voltage (load voltage) on the output end side of the inductor L (24) becomes a control target value, and the voltage is output as a specific load power for the load in the consumer. The voltage on the input end side and the voltage on the output end side of the inductor L (24) are periodically acquired at a constant periodic interval. The voltage on the input end side of the inductor L (24) represents the independent input voltage input from the PV-PCS 30a to the storage PCS 20a. The control process shown in FIG. 5 is an example of cascade control.

[0045] In Fig. 5, the independent input voltage from the PV-PCS 30a input to the power storage PCS 20a is input to the circuit unit 43 as a feedback voltage. In the circuit unit 43, a current value input from the PV-PCS 30a (photovoltaic PCS input current) is calculated from the input feedback voltage and output to the minor control unit 42. In the circuit unit 43, a current value according to the voltage input from the minor control unit 42 to the circuit unit 43 is calculated and output to the minor control unit 42 again. In addition, the output voltage supplied from the circuit unit 43 to the load side is input to the minor control unit 42 as feedback information. In addition, the output voltage (output voltage of the power storage PCS 20a) is input to the calculator S1.

[0046] 5, a differential voltage (deviation) between the output voltage command value and the output voltage is calculated, and the differential voltage is input to the output voltage control unit 41. The output voltage command value is generated by the control unit of the power storage PCS 20a.

[0047] In the output voltage control unit 41, a current reference value for minor loop control in which the output voltage value of the power storage PCS 20a is set as a control target value is generated based on the differential voltage (deviation) calculated by the calculator S1. The current reference value generated in the output voltage control unit 41 is input to the minor control unit 42. In the minor control unit 42, the output current and the solar PCS input current, which are feedback-input from the circuit unit 43, are used as control variables and the output voltage is used as an operation variable, A tracking control is performed with the current reference value input from the output voltage control unit 41 as a target value. The minor control unit 42 performs current control based on the current values ​​of the output current and the solar PCS input current fed back from the circuit unit 43, and controls the output voltage to be constant. As a result, in the power storage PCS 20a, feedback control is performed based on the voltage value across the inductor L (24) so ​​that the load voltage becomes the control target value, and a specific load power is output.

[0048] 6 to 8 are diagrams showing simulation results of the control process according to this embodiment. In FIG. 6, the simulation results are illustrated when the operation mode of the storage PCS 20a transitions from a charging mode to a discharging mode in a state where the independent input output from the PV-PCS 30a is connected to the connection point 2a via the inductor L (24), and the output current of the PV-PCS 30a changes to 0A at the same time. In FIG. 6(a), the transition of the voltage of the PV-PCS 30a input to the storage PCS 20a is illustrated, in FIG. 6(b), the transition of the voltage of the specific load power supplied to the load in the consumer is illustrated, and in FIG. 6(c), the transition of the output voltage of the power conversion unit (INV) 33 of the storage PCS 20a is illustrated. In FIG. 6(a) to (c), the vertical axis represents the voltage value, and the horizontal axis represents the passage of time. Fig. 6(d) illustrates the transition of the output current of the power conversion unit (INV) 33 of the storage PCS 20a, Fig. 6(e) illustrates the transition of the current of the specific load power supplied to the load in the consumer, and Fig. 6(f) illustrates the transition of the power output from the storage PCS 20a. The horizontal axis of Fig. 6(d) to (f) represents the passage of time, the vertical axis of Fig. 6(d) and (e) represents the current value, and the vertical axis of (f) represents the power value. The dashed lines in each graph represent the timing when the power supplied to the load is switched from the PV-PCS 30a to the storage PCS 20a.

[0049] As shown in Figures 6(a) to (f), it can be seen that the current values, voltage values, and power values ​​are supplied continuously without any temporary interruption before and after the switching. Note that, as shown in Figure 6(f), when the power supplied to the load is switched from the PV-PCS 30a to the storage PCS 20a, a time lag occurs due to the calculation process until a specified power value (for example, from 0 W to 1000 W) is output, but as shown in Figures 6(b) and (e), it can be seen that the power value supplied as the specific load power is supplied continuously.

[0050] FIG. 7 illustrates a simulation result in the case where the power supplied to the specific load is switched from the PV-PCS 30a to the storage PCS 20a during charging of the storage PCS 20a. The types of graphs in FIG. 7(a) to (f) are the same as those in FIG. 6. As shown in FIG. 7(a) to (f), it can be seen that the current value, voltage value, and power value are continuously supplied without temporary interruption before and after the switching. Also, in this form, a time lag occurs due to the calculation process until a predetermined power value (for example, from -150 W to 1000 W) is output from the storage PCS 20a, but as shown in FIG. 7(b) and (e), it can be seen that the power value supplied as the specific load power is continuously supplied. Note that in FIG. 7(f), the power value before the power supplied to the load is switched from the PV-PCS 30a to the storage PCS 20a is a negative value, but this is because the storage PCS 20a is charging.

[0051] FIG. 8 illustrates a simulation result of power supplied to a specific load when the PV-PCS 30a and the storage PCS 20a are operated in parallel. The types of graphs in FIG. 8(a) to (f) are the same as those in FIG. 6. As shown in FIG. 8(a) to (f), the PV-PCS 30a and the storage PCS 20a controlled using the voltage on the input end side and the voltage on the output end side of the inductor L (24) operate in parallel, and it can be seen that power related to the load is stably supplied. For this reason, the current transition of the specific load power supplied to the load in the consumer shown in FIG. 8(e) is the sum of the current values ​​output from the PV-PCS 30a and the storage PCS 20a. As shown in FIG. 8(f), in the parallel operation, the storage PCS 20a and the PV-PCS 30a operate in parallel. It can be seen that a power of about 200 W is being output.

[0052] As described above, in the distributed power system 1 according to this embodiment, the power storage PCS 20a of the power storage device 2 includes the inductor L (24), and the independent output output from the PV-PCS 30a can be input through the inductor L. The independent output output from the PV-PCS 30a is input, for example, through the independent input terminal 2b. By connecting the independent output output from the PV-PCS 30a through the inductor L (24) to the connection point 2a, in the distributed power system 1 according to this embodiment, it becomes possible to perform voltage control individually at both ends of the inductor L.

[0053] For example, the PV-PCS 30a of the power generation device 3 performs voltage control of the independent output during independent operation based on sensor information detected by a power sensor 25 provided on the input end side of the inductor L (24). Also, the power storage PCS 20a of the power storage device 2 performs voltage control of the independent output in a discharge mode during independent operation based on a measurement value detected by a power meter 81 provided on the output end side of the inductor L (24). In this embodiment, the PV-PCS 30a performs feedback control of the voltage on the input end side of the inductor L (24) as a control target value, converts the power generated by the photovoltaic power generation module 37 into AC power and outputs it, and the power storage PCS 20a can perform power storage control processing related to charging and discharging based on the voltages on the input end side and output end side of the inductor L (24). The power storage PCS 20a can perform feedback control so that the voltage (load voltage) on the output end side of the inductor L (24) becomes the control target value, and discharges the power stored in the storage battery unit 27. According to the distributed power system 1 of this embodiment, the voltages across the inductor L (24) can be controlled separately, so there is no interference between the output voltage control during discharging of the power storage device 2 and the output voltage control of the power generation device 3. In this embodiment, during independent operation, when switching the power storage device 2 from the charge mode to the discharge mode, continuous power supply is possible without temporarily stopping the operation of the load.

[0054] (others) The above embodiment is merely an example, and the disclosure of the present embodiment may be modified as appropriate within the scope of the gist of the present disclosure. The processes and means described in the present disclosure may be freely combined and implemented as long as no technical contradiction occurs. For example, the embodiment disclosed in the present embodiment may be applied to an electric vehicle (EV, Electric Vehicle) equipped with a storage battery such as a battery and a power generation mechanism using regenerative energy. Furthermore, the embodiment may be applied to a solar car equipped with a solar power generation module as a power generation mechanism, or a fuel cell car equipped with a fuel cell. Even in such an embodiment, it is possible to control the power output from the power generation mechanism and the storage battery without interference.

[0055] Furthermore, a process described as being performed by one device may be shared and executed by multiple devices. Or, a process described as being performed by different devices may be executed by one device. In a computer system, the hardware configuration for implementing each function can be flexibly changed.

[0056] <Computer-readable recording medium> A program for causing an information processing device or other machine or device (hereinafter, computer, etc.) to realize any of the above functions can be recorded on a recording medium readable by the computer, etc. Then, the computer, etc. can provide the function by reading and executing the program from the recording medium.

[0057] Here, a computer-readable recording medium is a medium that stores information such as data and programs electrically, magnetically, optically, mechanically, or chemically and that can be read by a computer or the like. This refers to a recording medium that can be read from a computer. Examples of such recording media that can be removed from a computer include flexible disks, magneto-optical disks, CD-ROMs, CD-R / Ws, DVDs, Blu-ray disks, DAT, 8mm tapes, and memory cards such as flash memory. Examples of recording media that are fixed to a computer include hard disks and ROMs.

[0058] In the following, the components of the present invention will be described with reference to the reference numerals in the drawings in order to make it possible to compare the components of the present invention with the configurations of the embodiments. <Invention 1> A power supply system (1) including a first power supply device (2) and a second power supply device (3), capable of supplying AC power output from at least one of the first power supply device (2) and the second power supply device (3) to a load (50), the first power supply device (2) includes an inductor (24) having one end connected to the AC power output from the second power supply device (3) and the other end connected to a connection point (2a) of a path connecting the first power supply device (1) and the load (50); The second power supply device (3) performs feedback control to set a voltage value related to one end of the inductor (24) to a control target value, the first power supply device (2) performs feedback control to set a voltage value related to the other end of the inductor (24) to a control target value, thereby controlling an output voltage of AC power supplied from the first power supply device (2) to the load (50); A power supply system (1). [Explanation of symbols]

[0059] 1 Distributed power systems 2. Energy storage device 2a Connection point 3. Power generation equipment 20, 20a Power conditioner (storage PCS) 21, 21a Control section 22 Bidirectional DC / DC converter 23 Power conversion section (INV) 24 Inductor 25, 28 Power sensor 27 Battery Unit 30, 30a Power Conditioner (PV-PCS) 31, 31a Control section 32 DC / DC converter 33 Power conversion section 37 Photovoltaic Module 38 Power Sensor 41 Output voltage control section 42 Minor Control Section 43 Circuit section 50 Load 80 Power system 81 Power meter 101 Processor 102 Main storage 103 Auxiliary storage device 104 Communication Interface 105 Input / Output Interface 106 Connection Bus

Claims

1. A power supply system including a first power supply device and a second power supply device, capable of supplying AC power output from at least one of the first power supply device and the second power supply device to a load, the first power supply device includes an inductor having one end connected to the AC power output from the second power supply device and having the other end connected to a connection point of a path connecting the first power supply device and the load; The second power supply device performs feedback control to set a voltage value related to one end of the inductor to a control target value, and the first power supply device controls an output voltage of AC power supplied from the first power supply device to the load by performing feedback control to set a voltage value related to the other end of the inductor to a control target value; A power supply system comprising:

2. The first power supply device is A power storage device including a storage battery and a first power conditioner connected to the storage battery, 2. The power supply system according to claim 1, wherein, when a charge mode is designated as the operation mode of the power storage device, the first power conditioner converts AC power supplied from the second power supply device to the connection point via the inductor into DC power and charges the storage battery, and, when a discharge mode is designated as the operation mode of the power storage device, converts DC power discharged from the storage battery into AC power and controls an output voltage of the AC power based on a voltage value associated with the other end of the inductor.

3. The first power conditioner includes: a first control unit that generates a current reference value from a deviation between a voltage value of the AC power output to the other end of the inductor and an output voltage command value; and a second control unit that performs tracking control with a feedback amount based on a voltage value related to one end of the inductor and an output voltage value of the AC power supplied to the load as a control variable, a voltage value of the AC power output to the other end of the inductor as a manipulated variable, and the current reference value as a target value.

4. The second power supply device is A power generation device having a solar power generation module and a second power conditioner connected to the solar power generation module, 3. The power supply system according to claim 1, wherein the second power conditioner converts DC power generated by the photovoltaic power generation module into AC power based on a control command related to a voltage value related to one end of the inductor and maximum power point tracking control or DC voltage control for keeping the DC voltage input from the photovoltaic power generation module constant at a predetermined value, and outputs the AC power to one end of the inductor.

5. A control method for a power supply system including a first power supply device and a second power supply device, capable of supplying AC power output from at least one of the first power supply device and the second power supply device to a load, comprising: the first power supply device includes an inductor having one end connected to the AC power output from the second power supply device and having the other end connected to a connection point of a path connecting the first power supply device and the load; The second power supply device executes feedback control to set a voltage value related to one end of the inductor to a control target value; A feed control circuit is provided for controlling a voltage value related to the other end of the inductor to a control target value. and executing a feedback control to control an output voltage of AC power supplied from the first power supply device to the load. A control method for executing the above.

6. A power conditioner of a power supply system including a first power supply device and a second power supply device, capable of supplying AC power output from at least one of the first power supply device and the second power supply device to a load, The power conditioner comprises: an inductor having one end connected to the AC power output from the second power supply device and the other end connected to a connection point of a path connecting the first power supply device and the load; The second power supply device performs feedback control to set a voltage value related to one end of the inductor to a control target value, and the first power supply device controls an output voltage of AC power supplied from the first power supply device to the load by performing feedback control to set a voltage value related to the other end of the inductor to a control target value; The power conditioner is characterized by the above.

Images