Power system and detection method

Abstract

To provide an electric power system and a detection method capable of appropriately detecting erroneous connection of a cable to be connected with an external power supply.SOLUTION: An electric power system comprises: a first converter that converts an AC power output from an external power supply into a DC power; a second converter that converts the DC power into an AC power; and a control unit that detects erroneous connection between a first power interface for supplying an AC power from AC wiring in a facility that can be connected with a power system and a second power interface for receiving the AC power output from the external power supply. The control unit detects erroneous connection between the first power interface and the second power interface in a case where increase or decrease of at least any one of a value related to the AC power supplied form the power system, a value related to the DC power output from the first converter, and a value related to the AC power output from the second converter is detected as a specific pattern.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power system and a detection method. [Background technology]

[0002] BACKGROUND ART In recent years, technology that utilizes an electricity storage device to stabilize the supply and demand balance in an electric power system (for example, VPP (Virtual Power Plant)) has been attracting attention (for example, Patent Document 1).

[0003] The facility also has a socket (hereinafter referred to as an outdoor socket) for supplying AC power from AC wiring within the facility. For example, the outdoor socket is an outdoor socket installed in a position (for example, on the exterior wall of a building) that allows power to be supplied to the outside of the facility. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2015 / 041010 Brochure [Patent Document 2] International Publication No. 2016 / 084396 Brochure Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors have focused on the effective use of DC power by utilizing a converter that converts AC power output from an external power source, such as an electric vehicle (EV), into DC power. For example, the DC power may be used to charge a power storage device. In such a case, the AC power output from the external power source may be supplied via a connector connected to the converter that converts the AC power output from the external power source into DC power.

[0006] However, the shape of the connector for supplying AC power from an external power source is assumed to be the same as the shape of the outdoor socket, and there is a possibility of an incorrect connection where the cable for connecting the external power source and the connector is connected to the outdoor socket.

[0007] Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a power system and a detection method that appropriately detects incorrect connection of a cable for connecting to an external power source. [Means for solving the problem]

[0008] One aspect of the disclosure is a power system comprising a first converter that converts AC power output from an external power source into DC power, a second converter that converts the DC power into AC power, and a control unit that detects a misconnection between a first power interface for supplying AC power from AC wiring within a facility that can be connected to a power system and a second power interface for receiving AC power output from the external power source, wherein the control unit detects a misconnection between the first power interface and the second power interface when an increase or decrease in at least one of a value related to AC power supplied from the power system, a value related to DC power output from the first converter, and a value related to AC power output from the second converter is detected as a specific pattern.

[0009] One aspect of the disclosure is a detection method comprising: step A of converting AC power output from an external power source into DC power using a first converter; step B of converting the DC power into AC power using a second converter; and step C of detecting a misconnection between a first power interface for supplying AC power from AC wiring in a facility that can be connected to a power grid and a second power interface for receiving the AC power output from the external power source, wherein step C includes a step of detecting a misconnection between the first power interface and the second power interface when an increase or decrease in at least one of a value related to the AC power supplied from the power grid, a value related to the DC power output from the first converter, and a value related to the AC power output from the second converter is detected as a specific pattern. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a power system and a detection method that appropriately detect an incorrect connection of a cable for connecting to an external power source. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a power system 1 according to an embodiment. [Figure 2] FIG. 2 is a diagram for explaining an erroneous connection according to the embodiment. [Figure 3] FIG. 3 is a diagram for explaining an erroneous connection according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating a detection method according to an embodiment. [Figure 5] FIG. 5 is a diagram illustrating a detection method according to an embodiment. [Figure 6] FIG. 6 is a diagram illustrating a detection method according to an embodiment. [Figure 7] FIG. 7 is a diagram illustrating a detection method according to an embodiment. [Figure 8] FIG. 8 is a diagram illustrating a detection method according to an embodiment. [Figure 9]FIG. 9 is a diagram showing a power system 1 according to the first modification. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic.

[0013] [Embodiment] (Power System) The following describes a power system according to an embodiment. As shown in Fig. 1, the power system 1 includes a solar cell device (hereinafter referred to as PV) 110, a power storage device (hereinafter referred to as BT) 120, an electric vehicle (hereinafter referred to as EV) 130, a load 140, and a measuring device 150. The power system 1 includes a PCS (Power Conditioning System) 200 and a distribution board 300. The power system 1 also includes a connector 400 and a power socket 500.

[0014] Although not particularly limited, the PV 110, BT 120, load 140, PCS 200, distribution board 300, connector 400, and power socket 500 may be installed inside or outside a building that constitutes the facility. The EV 130 may be parked within the premises of the facility.

[0015] The PV 110 is a distributed power source that generates power in response to light such as sunlight. For example, the PV 110 is configured by a solar panel. In the embodiment, the PV 110 is an example of a specified distributed power source that is connected to a converter 210 and connected via the converter 210 to a DC power line 200X through which DC power output from the converter 230 flows. The specified distributed power source may be considered to include the PV 110 and the converter 210.

[0016] The BT120 is a distributed power source that charges and discharges power. For example, the BT120 is configured with a power storage cell. The BT120 may be referred to as a stationary power storage device to distinguish it from a power storage device mounted on the EV130. In the embodiment, the BT120 is an example of a specified distributed power source that is connected to a converter 220 and connected via the converter 220 to a DC power line 200X through which DC power output from the converter 230 flows. The specified distributed power source may be considered to include the BT120 and the converter 220. However, the BT120 may be considered not to be included in the specified distributed power source in a disconnected state in which the facility is disconnected from the power grid 11.

[0017] EV 130 is a vehicle that includes a power storage device and is driven by electric power output from the power storage device. In the embodiment, the power storage device mounted on EV 130 is an example of an external power supply. Hereinafter, the power storage device mounted on EV 130 may be referred to as BT 130. BT 130 may be referred to as an in-vehicle power storage device to distinguish it from BT 120.

[0018] The load 140 is a device that consumes power. The load 140 may include video equipment, audio equipment, a refrigerator, a washing machine, an air conditioner, a personal computer, etc. The load 140 is electrically connected to the distribution board 300 by AC wiring 300X within the facility. The AC wiring 300X may also be referred to as in-house wiring 300X.

[0019] The measurement device 150 measures forward flow power (AC power) from the power grid 11 to the facility. The measurement device 150 may also measure reverse flow power (AC power) from the facility to the power grid 11. The measurement device 150 may be a reverse power prevention sensor for preventing reverse flow power from the facility to the power grid 11.

[0020] The PCS 200 is a power conditioner compatible with the PV 110, the BT 120, and the BT 130. Specifically, the PCS 200 includes a converter 210, a converter 220, a converter 230, a converter 240, a control unit 250, and a group of switches (switches 261 to 263, and switches 271 to 273).

[0021] The converter 210 converts the voltage of the DC power output from the PV 110. The converter 210 may be referred to as a unidirectional DC / DC converter.

[0022] Converter 220 converts the voltage of the DC power output from BT 120. Converter 220 converts the voltage of the DC power output from converter 210, converter 230, and converter 240. Converter 220 may be referred to as a bidirectional DC / DC converter.

[0023] Converter 230 converts AC power input from connector 400 into DC power. Converter 230 may be referred to as an AC / DC converter. In the embodiment, when connector 400 and BT 130 are properly connected, converter 230 constitutes a first converter that converts AC power output from BT 130 into DC power.

[0024] Although not particularly limited, converter 230 may have a function of converting DC power output from converter 210, converter 220, or converter 240 into AC power. In such a case, converter 230 may be referred to as a bidirectional inverter.

[0025] Converter 240 converts DC power output from converter 210, converter 220, or converter 230 into AC power. Converter 240 converts AC power supplied from power grid 11 into DC power. Converter 240 may be referred to as a bidirectional inverter. In the embodiment, converter 240 constitutes a second converter that converts DC power output from converter 230 into AC power.

[0026] Here, the converter 210, the converter 220, the converter 230, and the converter 240 are electrically connected by a DC power line 200X through which DC power flows. The DC power line 200X may be referred to as a DC link unit 200X.

[0027] The control unit 250 controls the PCS 200. The control unit 250 may include at least one processor. The at least one processor may be configured by a single integrated circuit (IC), or may be configured by two or more circuits (such as integrated circuits and / or discrete circuits) that are communicatively connected.

[0028] For example, the control unit 250 may be connected to the converter 220, the converter 230, and the converter 240 by signal lines. The signal lines may be wired or wireless. The control unit 250 may send control commands to the converter 220, the converter 230, and the converter 240. The control unit 250 may acquire various information from the converter 220, the converter 230, and the converter 240.

[0029] In the embodiment, the control unit 250 constitutes a control unit that detects a misconnection between the connector 400 and the power socket 500. The control unit 250 detects a misconnection between the connector 400 and the power socket 500 when a specific pattern of increase or decrease is detected in at least one of a value related to the AC power supplied from the power grid 11, a value related to the DC power output from the converter 230, and a value related to the AC power output from the converter 240. The detection of a misconnection will be described in detail later.

[0030] Although not particularly limited, the control unit 250 may be a controller installed inside the housing of the PCS, or may be a controller installed outside the housing of the PCS. The control unit 250 may also be a device (for example, an EMS; Energy Management System) installed separately from the PCS 200.

[0031] The switch 261 is a switch that switches the electrical connection state between the PV 110 and the converter 210. The switch 262 is a switch that switches the electrical connection state between the BT 120 and the converter 220. The switch 263 is a switch that switches the electrical connection state between the connector 400 and the converter 230.

[0032] Switch 271 is a switch that switches the electrical connection state between ELB 310 (electric power system 11) described below and converter 240. Switch 272 is a switch that switches the electrical connection state between in-facility breaker 320 described below and converter 240. Switch 273 is a switch that switches between a grid-connected state in which the facility is connected to power system 11 and a disconnected state in which the facility is disconnected from power system 11.

[0033] The distribution board 300 includes an ELB (Earth Leakage Breaker) 310 and an in-facility breaker 320 .

[0034] The ELB 310 is a breaker that interrupts a ground fault when a ground fault occurs. The ELB 310 is electrically connected to the power grid 11. The ELB 310 may also be referred to as a ground fault circuit interrupter.

[0035] The in-house breaker 320 is a breaker that cuts off the in-house wiring 300X when the current in the in-house wiring 300X exceeds a threshold. The in-house breaker 320 is connected to the in-house wiring 300X. The in-house breaker 320 may be called a safety breaker or a circuit breaker.

[0036] The connector 400 is an interface electrically connected to the PCS 200 (specifically, the converter 230). The connector 400 is a connection interface into which a connector 612 constituting one end of a cable 611 for connecting the BT 130 and the PCS 200 is inserted. A plug 613 constituting the other end of the cable 611 is inserted into a power socket electrically connected to the BT 130. In the embodiment, the connector 400 constitutes a second power interface for receiving AC power output from the BT 130.

[0037] Although not particularly limited, the connector 400 may be disposed on the outer wall of a building that constitutes the facility.

[0038] Here, connector 612 only needs to have a shape that allows it to be connected to connector 400. Therefore, connector 612 does not need to have the shape of a general-purpose plug (for example, an A-type plug), and may have a shape that is dedicated to PCS 200. On the other hand, plug 613 has a shape that allows it to be inserted into a general-purpose power socket that EV 130 or the like has, and may have the shape of a general-purpose plug (for example, an A-type plug).

[0039] The power socket 500 is an interface electrically connected to the indoor wiring 300X. It is a connection interface into which a plug 713 constituting one end of a cable 711 for connecting a load 140X is inserted. The other end of the cable 711 is electrically connected to the load 140X. The load 140X is a load that can be connected to the power socket 500, and is conveniently distinguished from the load 140 described above. In the embodiment, the power socket 500 constitutes a first power interface for supplying AC power from the indoor wiring 300X.

[0040] Although not particularly limited, the power socket 500 may be arranged on the outer wall of a building that constitutes the facility. The power socket 500 may be arranged near the connector 400 on the outer wall of the building that constitutes the facility.

[0041] Here, plug 713 has a shape that allows it to be inserted into a general-purpose power socket 500, and may have the shape of a general-purpose plug (for example, an A-type plug). In other words, plug 713 of cable 711 may have the same shape as plug 613 of cable 611.

[0042] As described above, in the embodiment, the power system 1 includes the converter 230 and the connector 400 connected to the converter 220 by the DC link unit 200X, and therefore charging of the BT 120 from the BT 130 is realized by connecting the connector 400 and the BT 130 by the cable 611. That is, the DC power output from the converter 230 is used to charge the BT 120 without being converted into AC power.

[0043] Furthermore, since the power system 1 has the converter 230 and the connector 400 connected by the converter 240 and the DC link unit 200X, power supply from the BT130 to the indoor wiring 300X is realized by connecting the connector 400 and the BT130 by the cable 611.

[0044] (misconnection) The following describes a misconnection according to the embodiment. As described above, the plug 613 of the cable 611 has the same shape as the plug 713 that can be inserted into the power socket 500. Therefore, a misconnection in which the plug 613 of the cable 611 is inserted into the power socket 500, that is, a misconnection between the connector 400 and the power socket 500, is assumed.

[0045] Although not particularly limited to this, it is conceivable that a case may arise in which the cable 611 is mistakenly thought to be a cable for supplying driving power to the PCS200 (or BT120), and the driving power for the PCS200 (or BT120) is obtained from the power socket 500.

[0046] First, a description will be given of an erroneous connection in a grid-connected state in which the facility is connected to the power grid 11, with reference to Fig. 2. As shown in Fig. 2, a connector 612 of a cable 611 is connected to a connector 400, and a plug 613 of the cable 611 is inserted into a power socket 500. For the sake of simplicity, the description will be given assuming that there is no loss associated with power conversion when the operations of the PV 110 and the BT 120 are stopped.

[0047] (1A) Load power (for example, 1 kW) is supplied from the power grid 11 to the load 140.

[0048] (1B) The converter 230 detects the waveform of AC power via the cable 611 and therefore mistakenly recognizes that power is being supplied from the BT 130. The converter 230 draws incoming power (for example, 0.5 kW) from the connector 400, converts the drawn power (AC power) into DC power, and outputs the DC power to the DC link unit 200X.

[0049] (1C) The forward flow power supplied from the power grid 12 is insufficient for the total of the load power and the incoming power (for example, 1.5 kW), so the forward flow power increases.

[0050] (1D) Converter 240 of PCS 200 outputs AC power (for example, 0.5 kW). As the AC power output by converter 240 increases, the forward flow power supplied from power grid 12 to the facility decreases.

[0051] (1E) Because the power drawn from the connector 400 decreases, the voltage of the DC link unit 200X (e.g., the voltage at the output end of the converter 230) decreases below a threshold value (e.g., 320 V). The threshold value may be expressed as a range defined by an upper limit (e.g., 375 V) and a lower limit (e.g., 305 V). For example, the voltage of the DC link unit 200X decreases below the lower limit (e.g., 305 V).

[0052] (1F) The AC power output by the converter 240 of the PCS 200 decreases. In response to the decrease in the AC power output by the converter 240, the forward flow power supplied from the power grid 12 to the facility increases.

[0053] From (1G) onwards, the above-mentioned operations (1B) to (1F) (i.e., increase in incoming power, increase in output power of converter 240, decrease in forward flow power, decrease in incoming power, decrease in voltage of DC link unit 200X, decrease in output power of converter 240, increase in forward flow power, and increase in voltage of DC link unit 200X) are repeated. For example, the above-mentioned operations (1B) to (1F) occur within a predetermined period (3 msec).

[0054] As described above, even if a misconnection occurs between connector 400 and power socket 500, the misconnection is not detected and operation continues. Meanwhile, although the above description assumes that there is no loss associated with power conversion, in reality, loss occurs associated with power conversion. Therefore, due to the power loop via converter 240, loss continues to occur due to unnecessary power conversion in converters 230 and 240. Leaving the misconnection as described above is inappropriate from the perspective of power conservation.

[0055] Secondly, a description will be given of a misconnection in a disconnected state in which the facility is disconnected from the power grid 11, with reference to Fig. 3. As shown in Fig. 3, a connector 612 of a cable 611 is connected to a connector 400, and a plug 613 of the cable 611 is inserted into a power socket 500. For the sake of simplicity, the description will be given assuming that there is no loss associated with power conversion when the operation of the PV 110 is stopped.

[0056] (2A) The converter 220 converts the voltage of the DC power output from the BT 120 and outputs the DC power to the DC link unit 200X. The converter 240 converts the DC power into AC power and outputs the AC power. Therefore, load power (for example, 1 kW) is supplied from the PCS 200 to the load 140.

[0057] (2B) The converter 230 detects the waveform of AC power via the cable 611 and therefore mistakenly determines that power is being supplied from the BT 130. The converter 230 draws incoming power (for example, 0.5 kW) from the connector 400, converts the drawn power (AC power) into DC power, and outputs the DC power to the DC link unit 200X.

[0058] (2C) Because the output power (AC power) of the PCS 200 is insufficient relative to the sum (e.g., 1.5 kW) of the load power and the incoming power, the voltage of the DC link unit 200X (e.g., the voltage at the output end of the converter 230) falls below a threshold value (e.g., 320 V). The threshold value may be expressed as a range defined by an upper limit (e.g., 375 V) and a lower limit (e.g., 305 V). For example, the voltage of the DC link unit 200X falls below the lower limit (e.g., 305 V).

[0059] (2D) The converter 220 increases the output power of the converter 220 in response to the decrease in the voltage of the DC link unit 200X. Therefore, the voltage of the DC link unit 200X increases.

[0060] (2E) In response to an increase in the voltage of the DC link unit 200X, the converter 230 increases the power drawn from the connector 400. The increase in the power drawn may be a predetermined amount (for example, 0.5 kW).

[0061] From (2F) onwards, the above-mentioned operations (2B) to (2E) (i.e., increase in the incoming power, increase in the output power of the converter 240, decrease in the voltage of the DC link unit 200X, increase in the output power of the converter 220, and increase in the voltage of the DC link unit 200X) are repeated. For example, the above-mentioned operations (2B) to (2E) occur within a predetermined period (3 msec).

[0062] When the output power of the (2G) converter 240 reaches its maximum rated power (eg, 5 kW), the converter 230 stops increasing the power drawn.

[0063] As described above, even if a misconnection occurs between connector 400 and power socket 500, the misconnection is not detected and operation continues. Meanwhile, although the above description assumes that there is no loss associated with power conversion, in reality, loss occurs associated with power conversion. Therefore, due to the power loop via converter 240, loss continues to occur due to unnecessary power conversion in converters 230 and 240. Leaving the misconnection as described above is inappropriate from the perspective of power conservation.

[0064] (Detection method) A method for detecting an erroneous connection will be described below, with the operation of control unit 250 being mainly described below.

[0065] As shown in FIG. 4, in step S11, the control unit 250 determines whether a specific pattern is detected. The control unit 250 may determine whether a specific pattern occurs within a predetermined period (3 msec). The control unit 250 may determine whether a specific pattern occurring within the predetermined period (3 msec) is repeated a predetermined number of times. If a specific pattern is detected, the control unit 250 executes the process of step S12. If a specific pattern is not detected, the control unit 250 ends the series of processes.

[0066] The specific pattern is defined by an increase or decrease in at least one of the value related to the AC power supplied from the power grid 11, the value related to the DC power output from the converter 230, and the value related to the AC power output from the converter 240.

[0067] In step S12, the control unit 250 detects a misconnection between the connector 400 and the power socket 500. The control unit 250 may notify the user that a misconnection has occurred.

[0068] Here, the following options are possible for detecting a specific pattern used to detect a misconnection.

[0069] (Option 1) A method for detecting a misconnection in a grid-connected state will be described in Option 1. In Option 1, the specific pattern is defined by a value related to AC power supplied from the power grid 11.

[0070] 5, in step S21, the control unit 250 detects an increase in the forward flow power supplied from the power grid 11. The AC power may be measured by the measurement device 150. The AC power may be measured by a measurement device disposed on the output end side of the converter 240.

[0071] In step S22, the control unit 250 detects a decrease in the forward flow power supplied from the power grid 11.

[0072] In step S23, the control unit 250 detects whether steps S21 and S22 are detected as a specific pattern. The control unit 250 may determine whether a specific pattern occurring within a predetermined period (3 msec) is repeated a predetermined number of times.

[0073] As described above, in option 1, the control unit 250 may detect a misconnection between the connector 400 and the power socket 500 when, in a grid-connected state, a specific pattern of increase or decrease in the value of the tidal flow power supplied from the power system 11 is detected.

[0074] In option 1, the detection of a misconnection may be performed during a period when the operations of the PV 110 and the BT 120 are not stopped. However, the detection of a misconnection may also be performed during a period when the operations of the PV 110 and the BT 120 are stopped.

[0075] (Option 2) In option 2, a method for detecting a misconnection in a grid-connected state will be described. In option 2, the specific pattern is defined by a value related to the AC power supplied from the power grid 11 and a value related to the DC power output from the converter 230. Here, a case will be illustrated in which the voltage of the DC link unit 200X (hereinafter referred to as DC link voltage) is used as the DC power output from the converter 230.

[0076] 6, in step S31, the incoming power increases due to an incorrect connection between the connector 400 and the power socket 500. That is, the converter 230 mistakenly recognizes that power is being supplied from the BT 130. The control unit 250 may or may not detect the increase in the incoming power. The incoming power may be detected by the converter 230.

[0077] In step S32, the output power of converter 240 increases as the incoming power increases. Control unit 250 may detect the increase in the output power of converter 240, or may not detect the increase in the output power of converter 240. The output power may be detected by converter 240.

[0078] In step S33, as the output power of converter 240 increases, the forward flow power supplied from power grid 11 decreases. Control unit 250 detects the decrease in forward flow power supplied from power grid 11. The AC power may be measured by measurement device 150. The AC power may be measured by a measurement device arranged on the output end side of converter 240.

[0079] In step S34, the incoming power decreases in accordance with the decrease in the forward flow power. The control unit 250 may or may not detect the decrease in the incoming power.

[0080] In step S35, the DC link voltage decreases as the incoming power decreases. The control unit 250 detects the decrease in the DC link voltage. The DC link voltage is measured by a measuring device provided on the DC link unit 200X. The measuring device may be installed on the DC link unit 200X side of at least one of the converters 220, 230, and 240.

[0081] In step S36, an increase in forward flow power occurs due to a power shortage relative to the sum of the load power and the incoming power. The control unit 250 detects the increase in forward flow power supplied from the power grid 11.

[0082] In step S37, the incoming power increases in accordance with an increase in the forward flow power supplied from the power grid 11. The control unit 250 may or may not detect the increase in the incoming power.

[0083] In step S38, the DC link voltage increases (recovers) as the draw power increases, and the control unit 250 detects the increase in the DC link voltage.

[0084] In step S39, the control unit 250 detects whether steps S32 to S38 are detected as a specific pattern. The control unit 250 may determine whether a specific pattern occurring within a predetermined period (3 msec) is repeated a predetermined number of times.

[0085] As described above, in option 2, the control unit 250 may detect a misconnection between the connector 400 and the power socket 500 when, in the interconnected state, a specific pattern of increase or decrease in the value related to the forward flow power supplied from the power grid 11 and an increase or decrease in the value related to the direct current power output from the converter 230 (here, the DC link voltage) is detected.

[0086] In option 2, if the control unit 250 is capable of detecting an increase or decrease in the value related to the output power of the converter 240, the control unit 250 may detect an improper connection between the connector 400 and the power socket 500 when, in addition to an increase or decrease in the value related to the forward power and an increase or decrease in the DC link voltage, an increase or decrease in the value related to the output power of the converter 240 is detected as a specific pattern.

[0087] In option 2, if the control unit 250 is capable of detecting an increase or decrease in the value related to the draw power of the converter 230, the control unit 250 may detect an incorrect connection between the connector 400 and the power socket 500 when the increase or decrease in the value related to the draw power of the converter 230 is detected as a specific pattern, in addition to the increase or decrease in the value related to the forward power and the increase or decrease in the DC link voltage.

[0088] In option 2, the detection of misconnection may be performed during a period when the operation of the specified distributed power sources (PV 110 and BT 120) is stopped. For example, the period when the operation of the PV 110 and BT 120 is stopped may be a period such as nighttime. Alternatively, under the assumption that the operation of the PV 110 and BT 120 is stopped for a certain period after the connector 612 of the cable 611 is connected to the connector 400, the period when the operation of the PV 110 and BT 120 is stopped may be such a certain period.

[0089] (Option 3) A method for detecting a misconnection in a disconnected state will be described in Option 3. In Option 3, the specific pattern is defined by a value related to the AC power output from the converter 240 (output power).

[0090] 7, in step S41, control unit 250 detects an increase in the output power of converter 240. The output power may be measured by converter 240, or may be measured by a measuring device installed on the output end side of converter 240.

[0091] In step S42, the control unit 250 detects a decrease in the output power of the converter 240.

[0092] In step S43, the control unit 250 detects whether steps S41 and S42 are detected as a specific pattern. The control unit 250 may determine whether a specific pattern occurring within a predetermined period (3 msec) is repeated a predetermined number of times.

[0093] As described above, in option 3, the control unit 250 may detect a misconnection between the connector 400 and the power socket 500 when a specific pattern of increase or decrease in the value of the output power of the converter 240 is detected in the disconnected state.

[0094] In option 3, the misconnection detection may be performed during a period when the operation of the PV 110 is not stopped. However, the misconnection detection may also be performed during a period when the operation of the PV 110 is stopped.

[0095] In option 3, when the remaining charge of the BT 120 is equal to or less than a threshold value (for example, a lower limit of the SOC (State of Charge)), the misconnection may not be detected, but may be detected as a system error.

[0096] (Option 4) In option 4, a method for detecting a misconnection in a disconnected state will be described. In option 4, the specific pattern is defined by a value related to the AC power (output power) output from the converter 240 and a value related to the DC power output from the converter 230. Here, a case will be illustrated in which the voltage of the DC link unit 200X (hereinafter referred to as DC link voltage) is used as the DC power output from the converter 230.

[0097] 8, in step S51, the incoming power increases due to an incorrect connection between the connector 400 and the power socket 500. That is, the converter 230 mistakenly recognizes that power is being supplied from the BT 130. The control unit 250 may or may not detect the increase in the incoming power. The incoming power may be detected by the converter 230.

[0098] In step S52, the output power of converter 240 increases as the incoming power increases. Control unit 250 may detect the increase in the output power of converter 240, or may not detect the increase in the output power of converter 240. The output power may be detected by converter 240.

[0099] In step S53, the DC link voltage decreases due to a shortage of the output power of the converter 240 relative to the sum of the load power and the incoming power. The control unit 250 detects the decrease in the DC link voltage. The DC link voltage is measured by a measuring device provided on the DC link unit 200X. The measuring device may be installed on the DC link unit 200X side of at least one of the converters 220, 230, and 240.

[0100] In step S54, the output power of the converter 220 increases as the DC link voltage decreases. The control unit 250 may detect the increase in the output power of the converter 220. In step S55, the DC link voltage increases (recovers) in accordance with the increase in the output power of the converter 220. The control unit 250 detects the increase in the DC link voltage.

[0101] In step S56, the output power of the converter 240 increases as the DC link voltage increases. The control unit 250 may detect the increase in the output power of the converter 240.

[0102] In step S57, the incoming power increases in accordance with the increase in the output power of converter 240. Control unit 250 may or may not detect the increase in the incoming power.

[0103] In step S58, the control unit 250 detects whether steps S52 to S57 are detected as a specific pattern. The control unit 250 may determine whether a specific pattern occurring within a predetermined period (3 msec) is repeated a predetermined number of times.

[0104] As described above, in option 4, the control unit 250 may detect a misconnection between the connector 400 and the power socket 500 when, in the disconnected state, a specific pattern is detected in the increase or decrease of the value related to the AC power (output power) output from the converter 240 and the increase or decrease of the value related to the DC power (here, the DC link voltage) output from the converter 230.

[0105] In option 4, if the control unit 250 is capable of detecting an increase in the output power (DC power) of the converter 220, the control unit 250 may detect a misconnection between the connector 400 and the power socket 500 when an increase in the value related to the output power of the converter 220 is detected as a specific pattern, in addition to an increase or decrease in the value related to the output power of the converter 240 and an increase or decrease in the DC link voltage.

[0106] In option 4, if the control unit 250 is capable of detecting an increase in the power draw of the converter 230, the control unit 250 may detect a misconnection between the connector 400 and the power socket 500 when an increase in the value of the power draw is detected as a specific pattern in addition to an increase or decrease in the value of the output power of the converter 240 and an increase or decrease in the DC link voltage.

[0107] In option 4, the detection of misconnection may be performed during a period when the operation of the specified distributed power source (PV 110) is stopped. For example, the period when the operation of the PV 110 is stopped may be a period such as nighttime. Alternatively, under the assumption that the operation of the PV 110 is stopped for a certain period after the connector 612 of the cable 611 is connected to the connector 400, the period when the operation of the PV 110 is stopped may be such a certain period.

[0108] (Action and effect) In the embodiment, control unit 250 detects a misconnection between connector 400 and power socket 500 when a specific pattern of increase or decrease is detected in at least one of a value related to AC power supplied from power grid 11, a value related to DC power output from converter 230, and a value related to AC power output from converter 240. With this configuration, when a new usage scenario is envisioned in which an external power source (e.g., EV 130) having a power socket shaped similar to general-purpose power socket 500 is used as a power supply source, it is possible to appropriately detect a misconnection between connector 400 and power socket 500.

[0109] [Change Example 1] Modification 1 of the embodiment will be described below, focusing mainly on the differences from the embodiment.

[0110] Specifically, in the embodiment, the PCS 200 corresponding to the PV 110, the BT 120, and the BT 130 is exemplified. In contrast to this, in the first modification, a PCS dedicated to the BT 130 is exemplified.

[0111] 9, the power system 1 has a PCS800 dedicated to the BT130, instead of the PCS200. The PCS800 has a converter 830 and a converter 840. Although not particularly limited, the PCS800 may be referred to as an EV power receiving unit. The power system 1 has a control unit 850, instead of the control unit 250.

[0112] Converter 830, like converter 230, converts AC power input from connector 400 into DC power. Converter 830 may also be referred to as an AC / DC converter. In Modification 1, when connector 400 and BT 130 are properly connected, converter 830 constitutes a first converter that converts AC power output from BT 130 into DC power.

[0113] Although not particularly limited, converter 830 may have a function of converting DC power output from converter 840 into AC power. In such a case, converter 830 may be referred to as a bidirectional inverter.

[0114] Converter 840 converts the DC power output from converter 830 into AC power, similar to converter 240. Converter 840 may be referred to as a DC / AC converter. In Modification 1, converter 840 constitutes a second converter that converts the DC power output from converter 830 into AC power.

[0115] Although not particularly limited, converter 840 may have a function of converting AC power supplied from power grid 11 into DC power. In such a case, converter 840 may be referred to as a bidirectional inverter.

[0116] Here, the converter 830 and the converter 840 are electrically connected by a DC power line 800X (DC link unit 800X).

[0117] Like the control unit 250, the control unit 850 detects an erroneous connection between the connector 400 and the power socket 500. The control unit 850 may be a controller for the PCS 800, a controller for the PCS 900, or an EMS.

[0118] Under such a premise, when the BT 120 is installed in parallel, the power system 1 may have a PCS 900 dedicated to the BT 120. Furthermore, when the PV 110 is installed in parallel, the power system 1 may have a PCS dedicated to the PV 110.

[0119] Modification example 1 is similar to the above-described embodiment, except that the BT130 and the distributed power sources (for example, the PV110, the BT120, etc.) are not connected by a DC power line, and the switches 271 to 273 are arranged outside the PCS800. Therefore, it is preferable to detect an incorrect connection between the connector 400 and the power socket 500. Although not particularly limited, the switches 271 and 272 may be arranged inside the PCS800, and the switch 273 may be arranged inside the distribution board 300.

[0120] [Other embodiments] Although the present invention has been described by the above-mentioned embodiments, the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. From this disclosure, various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art.

[0121] In the above-described Option 1, the control unit 250 may detect a misconnection using the output power of the converter 240 instead of the forward flow power supplied from the power grid 11. That is, the control unit 250 may detect a misconnection between the connector 400 and the power socket 500 when the value related to the output power of the converter 240 increases or decreases in a specific pattern.

[0122] In the above-described Option 1, the control unit 250 may detect a misconnection using the DC link voltage instead of the forward flow power supplied from the power grid 11. That is, the control unit 250 may detect a misconnection between the connector 400 and the power socket 500 when the increase and decrease in the DC link voltage occurs in a specific pattern.

[0123] In the above-described Option 3, the control unit 250 may detect a misconnection using the DC link voltage instead of the output power of the converter 240. That is, the control unit 250 may detect a misconnection between the connector 400 and the power socket 500 when the increase and decrease in the DC link voltage occurs in a specific pattern.

[0124] In the above disclosure, the EV 130 (BT 130) is given as an example of the external power source. However, the above disclosure is not limited to this. The external power source may include a power generation device such as an engine generator.

[0125] In the above disclosure, the PV 110 and the BT 120 are exemplified as distributed power sources installed in the facility. However, the above disclosure is not limited thereto. The distributed power sources installed in the facility may include one or more distributed power sources selected from a fuel cell device, a wind power generation device, a hydroelectric power generation device, a geothermal power generation device, and a biomass power generation device.

[0126] Although not specifically mentioned in the above disclosure, an increase or decrease in a value related to power may be detected by an increase or decrease in voltage, an increase or decrease in current, or an increase or decrease in power. In other words, the value related to power may be current, voltage, or power.

[0127] Although not specifically mentioned in the above disclosure, the term "disconnected state" may be read as "sustained state," the term "increase" may be read as "rise," and the term "decrease" may be read as "decrease."

[0128] Although not specifically mentioned in the above disclosure, the detection of a misconnection may be performed periodically or may be triggered by the connection of the cable 611 to the connector 400.

[0129] Although not specifically mentioned in the above disclosure, communication between units such as converter 220, converter 230, converter 240, control unit 250, and various measuring devices may be performed in accordance with a predetermined protocol (e.g., RS485, ECHONET Lite (registered trademark)).

[0130] Although not particularly limited, the connector 400 and the power socket 500 may have the same shape.

[0131] Although not specifically mentioned in the above disclosure, when converter 230 is a bidirectional inverter, charging of EV 130 (BT 130) may be performed. [Explanation of symbols]

[0132] 1...Power system, 11...Power grid, 110...PV, 120...BT, 130...EV(BT), 140, 140X...Load, 150...Measuring device, 200...PCS, 200X...DC power line (DC link section), 210...Converter, 220...Converter, 230...Converter, 240...Converter, 250...Control section, 261~263...Switch, 271~273...Switch, 300...min Panel, 300X...AC wiring (in-house wiring), 310...ELB, 320...In-house breaker, 400...Connector, 500...Power socket, 611...Cable, 612...Connector, 613...Plug, 711...Cable, 713...Plug, 800...PCS, 800X...DC power line (DC link section), 830...Converter, 840...Converter, 850...Control section, 900...PCS,

Claims

1. a first converter that converts AC power output from an external power supply into DC power; a second converter for converting the DC power into AC power; a control unit that detects an erroneous connection between a first power interface for supplying AC power from AC wiring in a facility that can be connected to an electric power grid and a second power interface for receiving AC power output from the external power source, The AC power converted by the second converter is supplied to the AC wiring, The control unit detects a misconnection between the first power interface and the second power interface when an increase or decrease in at least one of a value related to AC power supplied from the power system, a value related to DC power output from the first converter, and a value related to AC power output from the second converter is detected as a specific pattern.

2. 2. The power system according to claim 1, wherein the control unit detects a misconnection between the first power interface and the second power interface when an increase or decrease in a value related to AC power supplied from the power grid is detected as the specific pattern in a grid-connected state in which the facility is connected to the power grid.

3. 3. The power system according to claim 1, wherein, in a case where a specific distributed power source is installed and connected to a DC power line through which the DC power output from the first converter flows, the control unit executes a procedure for detecting a misconnection between the first power interface and the second power interface during a period in which the specific distributed power source is stopped.

4. 4. The power system according to claim 3, wherein the control unit detects a misconnection between the first power interface and the second power interface when an increase or decrease in a value related to AC power supplied from the power grid and an increase or decrease in a value related to DC power output from the first converter are detected as the specific pattern in a grid-connected state in which the facility is connected to the power grid.

5. 4. The power system according to claim 1, wherein the control unit detects a misconnection between the first power interface and the second power interface when an increase or decrease in a value related to the AC power output from the second converter is detected as the specific pattern in a disconnected state in which the facility is disconnected from the power grid.

6. the control unit executes a procedure for detecting a misconnection between the first power interface and the second power interface during a period when the specified distributed power source is stopped, when a specified distributed power source is installed and connected to a DC power line through which the DC power output from the first converter flows; 6. The power system according to claim 1, wherein the specific distributed power source is a distributed power source other than a power storage device connected to a DC power line through which the DC power output from the first converter flows.

7. 7. The power system according to claim 6, wherein the control unit detects a misconnection between the first power interface and the second power interface when an increase or decrease in a value related to the AC power output from the second converter and an increase or decrease in a value related to the DC power output from the first converter are detected as the specific pattern in a disconnected state in which the facility is disconnected from the power grid.

8. 8. The power system according to claim 1, wherein the DC power output from the first converter is used to charge a power storage device without being converted into AC power.

9. The power system according to claim 1 , wherein the external power supply is an on-board power storage device mounted on an electric vehicle.

10. Step A of converting AC power output from an external power supply into DC power by a first converter; Step B: converting the DC power into AC power by a second converter; and a step C of detecting an erroneous connection between a first power interface for supplying AC power from AC wiring in a facility that can be connected to an electric power grid and a second power interface for receiving AC power output from the external power source, The AC power converted by the second converter is supplied to the AC wiring, The detection method includes detecting a misconnection between the first power interface and the second power interface when an increase or decrease in at least one of a value related to AC power supplied from the power grid, a value related to DC power output from the first converter, and a value related to AC power output from the second converter is detected as a specific pattern.

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