JP2003087993A - Control method for surplus power in power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surplus power control method for power converters by which fine control of surplus power can be performed in an analog manner without using a dummy load, and increase of surplus power can be easily dealt with, even when more wind power generators and solar batteries are installed, and increase of surplus power is presumed. SOLUTION: At least one of a wind power generator 1 and a solar battery 2 is provided, power is supplied to a load 4 from that, and its surplus power is stored in a battery 3. When generated energy by the generator 1 and the solar battery 2 lowers, power is supplied by the battery 3 to the load 4. A power converter C' detects the charging current and the charged voltage of the battery 3, monitors surplus power, and charges its own output voltage according to its monitor result. According to this output voltage change, power converters A', B' change their own output powers. These output voltage and power changes are achieved, by changing reference voltages of feedback control loops in the power converters.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surplus power control method for a power supply system, and more particularly, it includes at least one of a wind power generator and a solar battery and a storage battery, and the wind power generator, the solar battery, and the storage battery are respectively the first and second batteries. 1 to 3
The storage battery is connected to the load in common through the power conversion device of, and the storage battery stores the surplus power of the power generated by the wind power generator and the solar battery, and supplies it to the load when the power generation amount of the wind power generator and the solar battery decreases. A surplus power control method for a power supply system that supplies power, which allows a storage battery to be charged with an appropriate charging current, and
The present invention relates to a surplus power control method in a power supply system that can prevent the overcharge.

[0002]

2. Description of the Related Art The power generated by a wind power generator or a solar cell is supplied to a load, the surplus power is stored in a storage battery, and the power stored in the storage battery is loaded when the amount of power generated by the wind power generator or the solar battery decreases. The power supply system that supplies power to the plant has attracted attention as a clean power supply system that effectively utilizes natural energy.

FIG. 4 is a block diagram showing a conventional power supply system, in which the power generated by the wind power generator 1 and the solar battery 2 is converted by the power converters A and B and supplied to the load 4. . The surplus power of the power generated by the wind power generator 1 and the solar cell 2 is the power conversion device A,
B is further supplied to the storage battery 3 via the power converter C and stored in the storage battery 3. Wind generator 1 and solar cell 2
When the amount of power generation of No. 2 decreases and it becomes impossible to sufficiently supply the electric power to the load 4, the electric power stored in the storage battery 3 is converted by the power conversion device C and supplied to the load 4.

Further, a dummy load 5 composed of, for example, a resistance load and a radiator is connected to the input side or the output side of the power conversion device C connected to the storage battery 3 so that the wind power generator 1 or Overcharge of the storage battery 3 is prevented when the amount of power generated by the solar cell 2 greatly exceeds the power demand of the load 4 and becomes excessive. That is, when the amount of power generated by the wind power generator 1 or the solar cell 2 exceeds the power demand of the load 4 and becomes a large surplus, the dummy load 5 is turned on and connected, whereby the surplus power is consumed to the storage battery 3. Excessive charging current and charging voltage are prevented. As a result, it is possible to stably supply electric power to the load 4 regardless of the strength of wind or sunlight and prevent overcharge of the storage battery 3.

[0005]

In the conventional power supply system, as described above, the dummy load 5 including a resistance load and a radiator is required to consume the surplus power. Further, in order to prevent the overcharge of the storage battery 3 due to the surplus power, the connection of the dummy load 5 must be controlled, but the control is difficult. That is, the surplus power is not always constant but fluctuates depending on the demand power of the load 4, and the fluctuation range also changes. In order to prevent the overcharge of the storage battery 3 due to such surplus power, the surplus power is adjusted according to the surplus power. It is necessary to control the connection and connection of the dummy load 5 in an analog manner.
Further, since it is the control of the timing of the input, it is difficult to finely control the control in an analog manner. Further, when the wind power generator 1 and the solar battery 2 are added and the increase of surplus power is predicted, the dummy load 5 must be added accordingly.

According to the present invention, control of surplus power for preventing overcharge of a storage battery can be finely performed in an analog manner without the need for a dummy load, and a wind power generator and a solar cell are additionally installed. It is an object of the present invention to provide a surplus power control method for a power supply system that can easily cope with a case where an increase in surplus power is predicted.

[0007]

In order to solve the above-mentioned problems, the present invention detects a charging current and a charging voltage of a storage battery by a power conversion device connected to the storage battery to monitor surplus power and monitors the surplus power. The first point is that the output voltage of itself is changed according to the result, and the output power of the power conversion device connected to the wind power generator and the output power of the power conversion device connected to the solar cell are changed according to the change in the output voltage. There is a feature of. A second feature of the present invention is that the output voltage of the power conversion device is changed by changing the reference voltage in the feedback control loop for stabilizing the output voltage according to the result of monitoring the surplus power. Furthermore, the present invention has a third feature in that the output power of the power converter is changed by changing the reference voltage in the feedback control loop that operates at the input side voltage of the power converter according to the output voltage. .

According to the first to third characteristics, the dummy load is not required, the control of the surplus power for preventing the overcharge of the storage battery can be finely performed in an analog manner, and the wind power generator can be used. It is possible to easily cope with a case where a solar cell is added and a surplus power is expected to increase. Further, since the feedback control function controls the excess power to be kept constant, the excess power is not controlled more than necessary, and the control with good responsiveness is performed even when a sudden excess power is generated.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing a power supply system to which an embodiment of the present invention is applied. 4 is different from that of FIG. 4 in that no dummy load is provided and the configuration of the power conversion devices A ′ to C ′ is different from that of the power conversion devices A to C. Information on the surplus power is transmitted to A'and B ', and the information on the surplus power is added to the feedback control loop in the power converters A'and B'to control the surplus power. Is. When the power supplied to the load 4 is alternating current, the power converter A '
May have a two-stage configuration having an AC-DC converter in the front stage and a DC-AC converter in the rear stage, and the power conversion devices B'and C'may be DC-AC converters. Not limited to this, when the power supplied to the load 4 is direct current, the power converter A ′ may be an AC-DC converter and the power converters B ′, C ′ may be a DC-DC converter. . The power converters A ′ to C ′ may be of the current control type or the voltage control type, or may be a combination thereof.

FIG. 2 is a basic control block diagram showing a specific example of the power converter A'or B'in FIG.
Here, only the part regarding the control of the surplus power related to the present invention is shown. Although a specific configuration for converting power is different between the power conversion devices A ′ and B ′ as described above, the configuration and operation thereof are well known and therefore omitted.

FIG. 3 is a basic control block diagram showing a specific example of the power conversion device C'in FIG. 1, and here also shows only the part relating to the control of the surplus power related to the present invention, and The specific configuration for conversion is omitted. The specified value Voref of the output voltage in FIGS.
13 and 18 have the same value.

The power generated by the wind power generator 1 or the solar cell 2 is converted by the power conversion power circuit 6 and then output as the output 7 of the power converter A'or B ', and supplied to the load 4 in FIG. It The surplus power of the output 7 is shown in FIG.
It is supplied to the storage battery 3 via the power conversion power circuit 16 and stored in the storage battery 3. The charging current for the storage battery 3 is detected by the current sensor 17. When the amount of power generated by the wind power generator 1 and the solar cell 2 is reduced and the output 7 cannot supply sufficient power to the load 4, the power stored in the storage battery 3 is transferred by the power conversion power circuit 16. It is converted and output as the output 7, and is supplied to the load 4 in FIG.

[0013] In FIG. 2, is amplified by the error amplifier 9 difference between the specified value Vdref _{1 8} of the output voltage and the DC voltage of the wind power generator 1 or the solar cell 2, the instantaneous value and the multiplier output and the output 7 It is multiplied by 10. Power circuit for power conversion 6
Current flowing from the output to the output 7 is detected by the current sensor 11,
The difference between this output and the output of the multiplier 10 is the error amplifier 12
The power circuit 6 for power conversion is controlled by this output. As a result, the output current of the power converter A'or B'is feedback-controlled so as to reach the output value of the multiplier 10. This feedback control circuit, further amplifies the difference between the specified value Voref13 output 7 and the output voltage, the error amplifier 14 and the diode 15 for adding a specified value Vdref _{1 8} DC voltage is provided.

In FIG. 3, the difference between the output 7 and the specified value Voref 18 of the output voltage is amplified by the error amplifier 19, and the output controls the power conversion power circuit 16.
As a result, the output 7 is feedback-controlled so as to become the specified value Voref 18 of the output voltage. This feedback control circuit has a specified value Vdr of the voltage of the storage battery 3 and the DC voltage.
an error amplifier 22, 23 and diode 24 for adding a specified value Voref18 the output voltage difference between the specified value Idref21 of the charging current and the direct current of the battery 3 which is detected by the differential and the current sensor 17 with the ef ₂ 20, 25 are provided.

Next, a surplus power control method according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3. The charging current and charging voltage to the storage battery 3 are the respective specified values I
Dref21, if Vdref ₂ 20 within the voltage value of the output 7, the power conversion power transistor 16 in FIG. 3,
The output voltage is regulated to the regulated value Voref18 and the regulated value Voref18 by the feedback control loop of the error amplifier 19.

When the power generation amount of the wind power generator 1 or the solar battery 2 increases and the output 7 exceeds the power demand of the load 4 and becomes a surplus, the charging current of the storage battery 3 increases. When the output of the current sensor 17 that detects this charging current becomes larger than the specified value Idref21 of the charging current, the difference between this output and the specified value Idref21 of the charging current is amplified by the error amplifier 23, and the specified value of the output voltage is passed through the diode 25. Voref1
Is added to 8. Further, when the voltage of the battery 3 is greater than the prescribed value Vdref ₂ 20 of the charging voltage, the difference is amplified by the error amplifier 22, it is added to the specified value Voref18 the output voltage through the diode 24. As a result, the specified value of the feedback control of the output voltage in the power conversion device C ′ rises, and as a result, the voltage value of the output 7 becomes larger than the specified value Voref18 of the output voltage.

[0017] In FIG. 2, if within the specified value Voref13 voltage value of the output 7 output voltage, the difference between the output of a specified value Vdref _{1 8} of the output voltage and the DC voltage of the wind power generator 1 or a solar cell 2 7 Result of multiplication with the instantaneous value of
Feedback control is performed based on the difference from the output detected at.

As described above, when the voltage value of the output 7 becomes larger than the specified value Voref18 of the output voltage, that is, Voref13, the output of the error amplifier 14 for amplifying the difference between the output 7 and the specified value Voref13 of the output voltage is the DC voltage. Prescribed value V
It is added to dref _{1 8,} the feedback control circuit of FIG. 2, the instantaneous value of the output 7, the output current detected by the current sensor 11, and the output of the output voltage error amplifier 14 of the wind power generator 1 or the solar cell 2 based control specified value Vdref _{1 8} summed DC voltage. Error amplifier 14
Result of the output is summed feedback control specified value Vdref _{1 8} DC voltage, the output power of the power conversion apparatus A 'or B' is decreased. This controls the excess power,
Excessive charging current and charging voltage for the storage battery 3 are prevented. When the charging current and the charging voltage for the storage battery 3 decrease, the voltage value of the output 7 decreases and the output power increases by the operation opposite to the above.

In the above description, the output voltage using the feedback control loop in the power converters A'to C ',
Although the embodiment in which the output power is changed has been described, the present invention is not limited to the one using the feedback control loop, and the output voltage and the output power are changed in an analog manner according to the monitoring result of the charging current and the charging voltage of the storage battery. Various configurations can be adopted. Further, although the power supply system using both the wind power generator and the solar cell has been described above, the present invention can be applied to a power supply system using one of the wind power generator and the solar cell, and It is also clear that the number of them is not limited, and such is also within the scope of the present invention. Further, even if a wind power generator or a solar cell is added, the surplus power is controlled by the power converter provided therein, so that it is clear that the dummy load need not be added.

[0020]

As is apparent from the above description, according to the inventions of claims 1 to 3, the dummy load is not required,
In order to prevent overcharging of the storage battery, the control of excess power can be finely controlled in an analog manner, and it has excellent responsiveness to sudden excess power generation, and does not control excess power more than necessary. Thus, the life of the storage battery can be extended and the natural energy can be effectively used. Further, it is possible to easily cope with the case where a wind power generator or a solar cell is additionally installed and an increase in surplus power is predicted. Further, since the information on the surplus power is transmitted using the distribution line connected to the load, a special signal line for transmitting the information on the surplus power between the power conversion devices is not required, and the power conversion device is not required. Can be distributed and arranged without any trouble.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing a power supply system to which an embodiment of the present invention is applied.

FIG. 2 is a basic control block diagram showing a specific example of the power converter A ′ or B ′ in FIG. 1.

FIG. 3 is a basic control block diagram showing a specific example of a power conversion device C ′ in FIG. 1.

FIG. 4 is a block diagram showing a conventional power supply system.

[Explanation of symbols]

1 ... Wind power generator, 2 ... Solar battery, 3 ... Storage battery, 4 ...
Load, 5 ... Dummy load, 6, 16 ... Power conversion power circuit, 7 ... Output, 8, 20 ... DC voltage specified value, 9,
12, 14, 19, 22, 23 ... Error amplifier, 10 ...
Multiplier, 11, 17 ... Current sensor, 13, 18 ... Specified value of output voltage, 15, 24, 25 ... Diode, 21 ...
..Regulated values of DC current, A'to C '... Power converters

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H02P 9/00 H02P 9/00 Z H01L 31/04 K F term (reference) 3H078 AA02 AA26 AA34 BB01 CC01 CC32 CC73 5F051 JA17 KA01 KA02 KA03 KA05 5G003 AA06 AA07 BA01 CA01 CA11 CC02 DA07 DA18 GB06 5H590 AA02 AB04 CA14 CA30 CD01 CD03 CE02 CE05 EA07 EA14 EB02 EB14 EB21 FA08 FC12 GA02 GA04 GA06 HA02 HA04 HA06 JA15 JB J07 J15 J15 J07

Claims (3)

[Claims] 1. A wind power generator and / or a solar battery, and a storage battery, wherein the wind power generator, the solar battery, and the storage battery are commonly connected to a load via first to third power converters. A power supply that is connected and stores the surplus power of the power generated by the wind power generator and the solar battery, and supplies power to the load when the power generation amount of the wind power generator and the solar battery decreases. In a surplus power control method for a system, the third power converter detects a charging current and a charging voltage of the storage battery to monitor surplus power, and an output voltage of the third power converter according to the monitoring result. Is changed, and the output power is changed by the first and second power conversion devices according to the change in the output voltage. A surplus power control method in a power supply system. 2. The output voltage of the third power converter is changed by changing the reference voltage in the feedback control loop for stabilizing the output voltage according to the monitoring result of the surplus power. Power control method in the power supply system of the above. 3. The first and second power converters of the first and second power converters are modified by changing a reference voltage in a feedback control loop that operates on the input side voltage of each of the first and second power converters according to the output voltage. The surplus power control method in the power supply system according to claim 1, wherein the output power is changed.