JP2014073042A - Control device, storage battery power conversion device, power system, and method for controlling power system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a storage battery power conversion device capable of improving followability of performing charging control with respect to rapid fluctuations in the amount of power generation of a solar cell and/or a load in a charging control of a storage battery whose power selling amount is made constant.SOLUTION: A control device monitors a current detection signal which is an analog signal from current sensor and inserted in the middle of a power line to a commercial system from a first connection point where a power conversion device and the commercial system are connect to each other, and controls charging power to a storage battery so that amounts of power to be bought and sold are made constant by a set value of the power selling amount.

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 above power system, the purpose is to cover the power consumed by the load by generating power from the solar cell and discharging the storage battery without receiving power from the grid-connected commercial system as much as possible, that is, without purchasing power from the power company. It is conceivable to provide an operation mode (clean mode).

  As charge control of the storage battery in the clean mode, it is conceivable to perform charge control of the storage battery so that the amount of power supplied from the system to the commercial system, that is, the amount of power sold to the power company is constant (zero as much as possible). However, the amount of power generated by the solar cell is likely to fluctuate due to fluctuations in the amount of solar radiation, and the load is also likely to fluctuate. If it is bad, there is a problem of purchasing power or selling more power than necessary.

  Therefore, the present invention provides a control device for a storage battery power conversion device that can improve the follow-up performance of the charge control with respect to a sudden change in the power generation amount and / or load of the solar battery in the charge control of the storage battery with a constant power sale amount. The purpose is to do.

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,
Connected to the first connection point connecting the power conversion device and the commercial system and the second connection point connecting the load, the discharge power from the storage battery is converted into power and output to the second connection point, A storage battery power conversion device that converts power input from the second connection point to charge the storage battery, and controls the storage battery power conversion device in a power system comprising:
The current detection signal, which is an analog signal from a current sensor inserted in the middle of the power line from the first connection point to the commercial system, is monitored to supply power to the storage battery so that the amount of power sold to the commercial system is constant. The charging power is controlled (first configuration).

Further, the control device configured as described above further monitors a current detection signal that is an analog signal from the current sensor, and controls the discharge power from the storage battery so that the amount of power purchased for the commercial system is constant,
When it is determined that a reverse power flow has occurred based on the current detection signal, the storage battery power conversion device is provided with a control for cutting off a switching unit that switches connection / cutoff between the storage battery and the commercial system. It is also possible (second configuration).

  Moreover, this invention sets it as the storage battery power converter device provided with the control apparatus of the said 1st structure or the 2nd structure.

  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,
Connected to the first connection point connecting the power conversion device and the commercial system and the second connection point connecting the load, the discharge power from the storage battery is converted into power and output to the second connection point, A storage battery power conversion device that converts power input from the second connection point to charge the storage battery, and a method for controlling the power system, comprising:
A current detection signal, which is an analog signal from a current sensor inserted in the middle of the power line from the first connection point to the commercial system, is monitored so that the amount of power sold to the commercial system is constant at the power sales amount setting value. And controlling the charging power to the storage battery.

  ADVANTAGE OF THE INVENTION According to this invention, in the charge control of the storage battery which makes electric power sale amount constant, the follow-up property of charge control with respect to the rapid fluctuation | variation of the electric power generation amount and / or load of a solar cell can be improved.

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 simple sensor such as a Hall element type sensor or a 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 is a current sensor used for grasping power sales and power purchases, and is configured similarly to the current sensor 5, for example.

  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 (switching unit), a control unit 35, It has.

  Between the connection point P2 and the bidirectional DC / AC converter 32, an interconnection relay 34 and a protection relay 33 that can be switched between connection and disconnection are sequentially connected. 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.

  The power system 100 having such a configuration consumes the household load 120 by generating power from the solar cell 1 and discharging the storage battery 41 without receiving power from the commercial grid 110 as much as possible, that is, without purchasing power from the power company. Operation in an operation mode (clean mode) for the purpose of supplying electric power is possible.

  First, the discharge control of the storage battery 41 in the clean mode will be described. Here, according to the grid connection regulations, it is prohibited to sell the electric power discharged from the storage battery 41 to the electric power company. Therefore, the following reverse power flow prohibition control is performed.

  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. As described above, by using the current detection signal as the analog signal from the current sensor 5, the reverse power flow from the storage battery 41 can be quickly prohibited.

  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).

  When the reverse power flow prohibition operation by the control unit 35 occurs, the storage battery power conditioner 3 is stopped. Therefore, in order to prevent this from occurring as much as possible, the following output control of the storage battery power conditioner 3 is performed.

Here, the amount of power generated by the solar cell 1 is P (kW) (= positive value), the household load 120 is R (kW) (= positive value), and the discharge power from the storage battery 41 is B (kW) (= (Positive value), if the amount of electricity purchased and sold for the system is A (kW) (the power purchase direction is a positive value) (see FIG. 1),
P + A + B = R (1)
That is, R- (P + B) = A (2)
Holds.

  The amount of power P generated 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 due to the influence of the lifestyle pattern of the installer. The control unit 35 monitors the value of the power purchase / purchase amount A by monitoring the detection signal from the current sensor 5, and the discharge power so that the value of A becomes constant at the power purchase amount set value (positive value). B is controlled. The control unit 35 controls the discharge power by driving and controlling the bidirectional DC / AC converter 32 and the bidirectional DC / DC converter 31.

  Thereby, since the amount of 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 the followability to the variation of a solar radiation amount or load.

  Next, charge control of the storage battery 1 in the clean mode will be described.

  In the above formulas (1) and (2), if the value of B is set to a negative value, B represents the charging power to the storage battery 41 (the reverse direction of the direction B shown in FIG. 1). As described above, the power generation amount P by the solar cell 1 is likely to fluctuate due to fluctuations in the amount of solar radiation, and the load R is also likely to fluctuate. In the charging mode, the control unit 35 monitors the detection signal from the current sensor 5. Thus, the value of the electric power sales amount A is monitored, and the charging power B is controlled so that the value of the electric power sales amount A is constant at the electric power sales amount setting value (negative value). The control unit 35 controls charging power by driving and controlling the bidirectional DC / AC converter 32 and the bidirectional DC / DC converter 31. The control unit 35 performs the charge control when the value of SOC (state of charge) that is the remaining amount of the storage battery 41 is lower than 100%. The power sale amount setting value can be set to zero.

  Thereby, since it controls based on the analog signal from the current sensor 5, it is excellent in the followable | trackability to the amount of solar radiation and load fluctuation | variation, and it can suppress purchasing electricity or selling more than necessary.

  If the same function is to be realized by the remote controller 7, the remote controller 7 acquires the power generation amount information and the home load information of the solar cell, and based on these, the charging power is controlled by the control unit 35 so that the power sales amount becomes constant. It is conceivable to order However, the communication between the remote controller 7 and the control unit 35 is RS485 compliant serial communication, and communication is performed in units of several seconds. Therefore, when the power generation amount of the solar cell 1 or the household load 120 changes rapidly after the command, the command value Is no longer appropriate and buys power or sells more power than necessary.

  Further, the control unit 35 may change the setting value of the positive value A during the discharge control of the storage battery 41 to a negative value during the charge control by a soft control. Can be shared and the cost can be reduced.

  In addition, since the electric power sale which generate | occur | produces in the said charge control, ie, a reverse power flow, is a thing by the surplus of the electric power generation by the solar cell 1, the said reverse power flow prohibition control is not performed at the time of charge control.

  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 (5)

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,
Connected to the first connection point connecting the power conversion device and the commercial system and the second connection point connecting the load, the discharge power from the storage battery is converted into power and output to the second connection point, A storage battery power conversion device that converts power input from the second connection point to charge the storage battery, and controls the storage battery power conversion device in a power system comprising:
A current detection signal, which is an analog signal from a current sensor inserted in the middle of the power line from the first connection point to the commercial system, is monitored so that the amount of power sold to the commercial system is constant at the power sales amount setting value. Controlling charging power to the storage battery,
A control device characterized by that. Monitoring the current detection signal, which is an analog signal from the current sensor, and controlling the discharge power from the storage battery so that the amount of electricity purchased and sold for the commercial system is constant at the electricity purchase amount setting value;
When it is determined that a reverse power flow has occurred based on the current detection signal, the storage battery power converter is equipped with a control unit that cuts off a switching unit that switches connection / cutoff between the storage battery and the commercial system.
The control device according to claim 1.   A storage battery power conversion device comprising the control device according to claim 1.   The power system provided with the storage battery power converter device of Claim 3, the said solar cell, the said power converter device, the said storage battery, and the said current sensor. 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,
Connected to the first connection point connecting the power conversion device and the commercial system and the second connection point connecting the load, the discharge power from the storage battery is converted into power and output to the second connection point, A storage battery power conversion device that converts power input from the second connection point to charge the storage battery, and a method for controlling the power system, comprising:
A current detection signal, which is an analog signal from a current sensor inserted in the middle of the power line from the first connection point to the commercial system, is monitored so that the amount of power sold to the commercial system is constant at the power sales amount setting value. A method for controlling an electric power system, further comprising: controlling charging power to the storage battery.

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