JP6009893B2 - Control device, storage battery power conversion device, and power system - Google Patents

Description

  The present invention relates to an electric power system including a solar battery and a storage battery.

  Recently, renewable energy that can be regenerated in a relatively short period of time even if it is used once and resources are not depleted is attracting attention. For example, power generation systems using sunlight are becoming popular.

  Moreover, the electric power system which combined the storage battery with the said photovoltaic power generation system is proposed conventionally (for example, refer patent document 1).

JP-A-10-2011129

  In the power system, the storage battery can be charged with power generated by sunlight or power supplied from a grid-connected commercial system. However, although the electric power charged in the storage battery may be used for load consumption by discharging, supplying the electric power charged in the storage battery to the grid side and selling it to the power company, so-called reverse power flow Prohibited by interconnection rules.

  Then, an object of this invention is to provide the control apparatus for storage battery power converter devices which can prohibit effectively the reverse power flow of the electric power charged by the storage battery.

In order to achieve the above object, the present invention provides:
Solar cells that generate sunlight and generate electricity;
A power conversion device for converting the power generated by the solar cell to output, and
A storage battery,
A storage battery power conversion device connected to a first connection point for connecting the power conversion device and a commercial system and a second connection point for connecting a load, and for converting the discharge power from the storage battery and outputting the power. A control device for controlling the storage battery power conversion device in the power system,
The current detection signal is received as an analog signal from a current sensor that is a CT sensor inserted in the middle of the power line from the first connection point to the commercial system, and it is determined that a reverse power flow has occurred based on the current detection signal. In this case, the storage battery power conversion device is configured to block a switching unit that switches connection / cutoff between the storage battery and the commercial system.

In the above configuration, the power system remotely controls the second current sensor inserted in the middle of the power line from the first connection point to the commercial system, the power converter, and the storage battery power converter. A remote controller (remote controller),
The control device may receive an instruction from the remote controller that has determined that a reverse power flow has occurred based on a current detection signal received from the second current sensor, and may change the operation mode of the storage battery power conversion device.

  In the above configuration, the change in the operation mode may be a change from a discharge mode in which power is discharged from the storage battery to a standby mode in which a charge / discharge instruction is received from the remote controller.

  In any one of the configurations described above, the remote controller may display purchased power and sold power based on a current detection signal received from the second current sensor through serial communication.

  Moreover, this invention makes it a storage battery power converter device provided with the control apparatus of one of the said structures, and the said switching part.

  Moreover, this invention sets it as the electric power system provided with the storage battery power converter device of the said structure, the said solar cell, the said power converter device, the said storage battery, and the said current sensor.

The present invention also provides:
Solar cells that generate sunlight and generate electricity;
A power conversion device for converting the power generated by the solar cell to output, and
A storage battery,
A storage battery power conversion device connected to a first connection point for connecting the power conversion device and a commercial system and a second connection point for connecting a load, and for converting the discharge power from the storage battery and outputting the power. A method for controlling an electric power system,
It is determined whether a reverse power flow has occurred based on a current detection signal as an analog signal output from a current sensor that is a CT sensor inserted in the middle of a power line from the first connection point to the commercial system. A determination step;
And a shutoff step of shutting off a switching unit provided in the storage battery power converter for switching between connection and disconnection of the storage battery and the commercial system when it is determined that a reverse power flow has occurred. A control method for the power system.

  According to the present invention, since the switching unit is cut off based on the current detection signal as an analog signal from the CT sensor having a simple configuration, the reverse power flow can be quickly prohibited.

It is a figure showing the whole electric power system composition concerning one embodiment of the present invention.

  An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of a power system according to an embodiment of the present invention.

  A power system 100 shown in FIG. 1 includes a solar cell 1, a power conditioner 2, a storage battery power conditioner 3, a storage battery box 4, a current sensor 5, a trade sensor 6, and a remote controller (remote controller) 7. ing.

  The solar cell 1 is a module formed by connecting a plurality of solar cells, for example, and generates direct-current power in response to sunlight.

  The power conditioner 2 (power conversion device) is a device that converts DC power generated by the solar cell 1 into AC power, and includes a DC / DC converter 21, a DC / AC converter 22, a protection relay 23, and an interconnection. Relay 24.

  The DC / DC converter 21 converts the DC power generated by the solar cell 1 into DC power having a predetermined voltage value. The DC / AC converter 22 converts the DC power output from the DC / DC converter 21 into AC power.

  On the output side of the DC / AC converter 22, a protection relay 23 and a connection relay 24 that can be switched between connection and disconnection are connected in order. The protection relay 23 and the interconnection relay 24 are both connected, and the output of the DC / AC converter 22 is output to the outside of the power conditioner 2 via the protection relay 23 and the interconnection relay 24.

  The current sensor 5 and the buying and selling sensor 6 are inserted in the middle of the power line connecting the interconnection relay 24 and the commercial system 110.

  The current sensor 5 is composed of a CT sensor (current transformer type sensor). The current sensor 5 outputs a detection signal indicating the current value and current direction of the current flowing through the power line as an analog signal.

  The trade sensor 6 (second current sensor) is a current sensor used for grasping power sales and power purchases, and is composed of, for example, a CT sensor.

  A household load 120 is connected to a connection point P1 (first connection point) connecting the interconnection relay 24 and the current sensor 5. The household load 120 is various electric devices (for example, a refrigerator, a television, an air conditioner, etc.) used in the home and consumes the supplied power. In addition, since the electric power system of this embodiment is not restricted to household use, a load is not restricted to household use either.

  The storage battery power conditioner 3 is connected to a connection point P2 (second connection point) between the connection point P1 and the household load 120.

  The storage battery power conditioner 3 (storage battery power conversion device) includes a bidirectional DC / DC converter 31, a bidirectional DC / AC converter 32, a protection relay 33, an interconnection relay 34, and a control unit 35. .

  Between the connection point P2 and the bidirectional DC / AC converter 32, an interconnection relay 34 (switching unit) and a protection relay 33 that can be switched between connection and disconnection are connected in order. When the protection relay 33 and the interconnection relay 34 are connected, the bidirectional DC / AC converter 32 converts the DC power from the bidirectional DC / DC converter 31 into AC power and outputs it to the connection point P2 side. AC power from P2 is converted to DC power and output to the bidirectional DC / DC converter 31 side.

  The bidirectional DC / DC converter 31 converts the direct current power from the bidirectional DC / AC converter 32 into direct current power of a predetermined voltage value, and charges the direct current power to the storage battery 41 in the storage battery box 4 or from the storage battery 41. The discharged DC power is converted into DC power having a predetermined voltage value and output to the bidirectional DC / AC converter 32 side.

  The storage battery 41 is composed of, for example, a lithium ion battery. Moreover, the storage battery box 4 can perform serial communication based on RS485 with the storage battery power conditioner 3, and transmits storage battery information to the storage battery power conditioner 3.

  The control unit 35 (control device) of the storage battery power conditioner 3 is configured by, for example, a combination of a microcomputer and a DSP (digital signal processor), and performs drive control of the bidirectional DC / DC converter 31 and the bidirectional DC / AC converter 32. The connection / disconnection switching control of the protection relay 33 and the interconnection relay 34 is performed.

  The remote controller 7 has a function of displaying various information and a function of accepting an operation input from a user, and is a controller that remotely controls the power conditioner 2 and the storage battery power conditioner 3.

  The remote controller 7 receives a detection signal indicating a current value and a current direction of the current flowing through the power line by serial communication based on RS485 from the trading sensor 6 which is a current sensor, and displays the purchased power and the sold power based on the detection signal. To do.

  In addition, the remote controller 7 receives solar battery power generation information from the power conditioner 2 and storage battery information from the storage battery power conditioner 3 from the storage battery box 4 through serial communication based on RS485, and also displays these information.

  In addition, the remote controller 7 instructs the power conditioner 2 and the storage battery power conditioner 3 to stop operation by serial communication conforming to RS485, or sets the operation mode to the control unit 35 of the storage battery power conditioner 3 by the serial communication. Also do.

  Here, the operation mode will be described. There are three operation modes: a discharge mode, a charge mode, and a standby mode. The discharge mode is a mode for discharging from the storage battery 41. The charging mode is a mode for charging the storage battery 41.

  The standby mode is a mode in which the current state of the storage battery 41 is maintained and a discharge or charge instruction from the remote controller 7 is awaited. For example, when the storage battery 41 is fully charged at night and waiting for a discharge instruction, or when the storage battery 41 is discharged to a specified remaining capacity and waiting for a recharge instruction. Further, switching between the discharge mode and the charge mode is performed through the standby mode.

  Next, the reverse power flow prohibition control according to the present embodiment will be described. When in the discharge mode, the control unit 35 of the storage battery power conditioner 3 receives a detection signal indicating a current value and a current direction of the current flowing through the power line as an analog signal from the current sensor 5, and a reverse power flow ( It is determined whether or not (power supply in the power selling direction) has occurred. For example, it is determined that a reverse power flow has occurred when power of 5% or more of the rating (100 W or more for a rated 2 kW) is supplied to the system for 0.5 seconds or more.

  When it is determined that a reverse power flow has occurred, the control unit 35 shuts off the interconnection relay 34 and stops the operation of the bidirectional DC / AC converter 32. Thus, the reverse power flow from the storage battery 41 can be quickly prohibited by using the current detection signal as an analog signal from the current sensor 5 which is a CT sensor having a simple configuration.

  In addition, when the reverse power flow is prohibited in this way, surplus power excluding the power consumed by the home load 120 out of the power generated by the solar power output from the power conditioner 2 is sold to the grid side. However, it is advantageous because the power selling price without so-called push-up power generation (double power generation) is applied (when the power selling price with push-up power generation is 36 yen / kWh, for example, when there is no push-up power generation. For example, 42 yen / kWh).

  In addition, the remote controller 7 receives a detection signal indicating the current value and current direction of the current flowing through the power line from the trading sensor 6 through RS485-compliant serial communication, and determines whether a reverse power flow has occurred based on the detection signal. To do. The criteria for determining reverse power flow are the same as above.

  When it is determined that the reverse power flow has occurred, the remote controller 7 instructs the control unit 35 to shift from the discharge mode to the standby mode by RS485-compliant serial communication. Thereby, the control part 35 transfers to standby mode.

  The reason for shifting the operation mode from the discharge mode to the standby mode as described above is that if the reverse flow prohibition control is operated as described above during the operation in the discharge mode, if the discharge mode is continued, the remote controller 7 This is because the display indicates that the discharge power is zero although it is in the discharge mode, which causes a misunderstanding that it is a failure of the user. Therefore, by shifting to the standby mode, the display on the remote controller 7 is in the standby mode and the discharge power is zero, thereby preventing misunderstanding of the user.

  Further, when a reverse power flow occurs and the interconnection relay 34 is interrupted as described above, the control unit 35 checks whether or not the reverse power flow disappears periodically (every few seconds). Since this check is performed with the interconnection relay 34 in a normal operating state connected (system connected), if the discharge mode is maintained, a reverse power flow may have occurred during the check. In this case, the interconnection relay 34 is cut off again. Accordingly, the disconnection of the interconnection relay 34 is frequently repeated, and there is a possibility that the deterioration of the interconnection relay 34 is accelerated. Therefore, by shifting from the discharge mode to the standby mode, the above-mentioned problem does not occur because the interconnection relay 34 is not shut off even if a reverse power flow occurs.

  In addition, since the storage battery power conditioner 3 stops when the reverse power flow prohibition operation by the control unit 35 occurs, the following output control of the storage battery power conditioner 3 is performed in order to prevent this from occurring as much as possible. It may be.

Here, if the amount of power generated by the solar cell 1 is P, the household load 120 is R, the discharged power from the storage battery power conditioner 3 is B, and the purchased power from the system is A,
P + A + B = R
That is, R- (P + B) = A
Holds.

  The power generation amount P by the solar cell 1 is likely to change due to fluctuations in the amount of solar radiation, and the load R is also likely to change. However, the control unit 35 monitors the detection signal from the current sensor 5 so that the value of the purchased power A is The discharge power B is controlled so as to be constant.

  Thereby, since the power purchased from the system is controlled to be constant, the occurrence of reverse power flow can be suppressed and the above-described reverse power flow prohibition operation can be suppressed. Moreover, since it controls based on the analog signal from the current sensor 5, it is excellent in followability to the amount of solar radiation and load fluctuations.

  The embodiment of the present invention has been described above, but the embodiment can be variously modified within the scope of the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Solar cell 2 Power conditioner 21 DC / DC converter 22 DC / AC converter 23 Protection relay 24 Interlocking relay 3 Storage battery power conditioner 31 Bidirectional DC / DC converter 32 Bidirectional DC / AC converter 33 Protection relay 34 Interlocking relay 35 Control 4 Storage battery box 41 Storage battery 5 Current sensor 6 Trading sensor 7 Remote control 100 Power system 110 Commercial system 120 Domestic load

Claims (4)

Solar cells that generate sunlight and generate electricity;
A power conversion device for converting the power generated by the solar cell to output, and
A storage battery,
A storage battery power conversion device connected to a first connection point for connecting the power conversion device and a commercial system and a second connection point for connecting a load, and for converting the discharge power from the storage battery and outputting the power. A control device for controlling the storage battery power conversion device in the power system,
A current detection signal is received as an analog signal from the first current sensor which is a CT sensor inserted in the middle of the power line from the first connection point to the commercial system, and a reverse power flow is generated based on the current detection signal When it is determined, the storage battery power conversion device is provided with the switching unit for switching between connection and disconnection of the storage battery and the commercial system ,
The power system includes a second current sensor inserted in the middle of a power line from the first connection point to the commercial system, and a remote controller (remote controller) for remotely controlling the power converter and the storage battery power converter. And further comprising
A control device that receives an instruction from the remote controller that has determined that a reverse power flow has occurred based on a current detection signal received from the second current sensor, and changes an operation mode of the storage battery power conversion device. The change of the operation mode from the discharge mode to discharge electric power from said storage battery control device according to claim 1, characterized in that a change to the standby mode waiting for the charging and discharging instruction from the remote controller. A storage battery power conversion device comprising the control device according to claim 1 or 2 and the switching unit. A power system comprising the storage battery power conversion device according to claim 3 , the solar cell, the power conversion device, the storage battery, the first current sensor, and the second current sensor .

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