JP2001298872A - Power storage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage system which can achieve the elongation of life of a power storage battery and the enhancement of its use efficiency. SOLUTION: In a power storage system, a controller 1 detects the open terminal voltage VO of a power storage battery 8, sets the upper limit value of the charge power/discharge power of the battery 8 based on the detection result, and keeps the charge power/discharge power at its upper limit value in case that the power to be charged/discharged is larger than the upper limit value. Accordingly, it can be prevented from being overcharged/overdischarged to elongate the life of the battery 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power storage system, and more particularly to a power storage system for stabilizing a power system.

[0002]

2. Description of the Related Art Conventionally, by storing excess power of a power system in a power storage battery and supplying power of the power storage battery to the power system when the power of the power system becomes insufficient, the frequency and voltage of the power system are reduced. A power storage system has been developed to stabilize electricity.

For example, when a wind power generator is linked to a power system on an isolated island, as shown in FIG. 7, the generated power PW of the wind power generator fluctuates according to the rotation of the blades and the fluctuation of the wind. When the generated power PW is larger than the target value, the excess is stored in the power storage tank (in this case, the output power P
out becomes negative), and when the generated power PW is smaller than the target value, the power Pout of the power storage battery is given to the power system. Thereby, PW + Pout becomes constant, and the frequency and voltage of the power system can be stabilized.

[0004]

However, in the conventional power storage system, the charge / discharge state of the power storage battery is not sufficiently managed and controlled, so that the battery is overcharged or overdischarged. There is a problem that the life of the battery is shortened and the use efficiency of the battery is low.

[0005] Therefore, a main object of the present invention is to provide a power storage system capable of extending the life of a power storage battery and improving its use efficiency.

[0006]

The invention according to claim 1 is
An electric power storage system for stabilizing an electric power system, wherein an electric power storage battery is charged with excess electric power of the electric power system, and a discharged state of the electric power storage battery is used to compensate for an insufficient electric power of the electric power system. State detecting means for detecting the power level, power level detecting means for detecting the level of excess or deficiency of the power of the power system, and charging for instructing the charging power / discharging power of the power storage battery based on the detection result of the power level detecting means. Discharge command means, and sets an upper limit value of the power to be charged to the power storage battery based on the detection result of the state of charge detection means, overcharge prevention means for preventing overcharge of the power storage battery,
If the charging power commanded by the charge / discharge command means is larger than the upper limit value set by the overcharge prevention means, the power of the upper limit value is charged into the power storage battery, otherwise, the command of the charge / discharge command means is issued. Charge / discharge executing means for charging / discharging the power storage battery in accordance with the following.

According to a second aspect of the present invention, in accordance with the first aspect of the present invention, an upper limit value of the discharge power of the power storage battery is set based on the detection result of the state-of-charge detection means, thereby preventing overdischarge of the power storage battery. For preventing over-discharge is further provided. The charging / discharging execution means discharges the power of the upper limit from the power storage battery when the discharge power commanded by the charge / discharge command means is larger than the upper limit value set by the overdischarge prevention means.

According to a third aspect of the present invention, there is provided an electric power storage system for stabilizing an electric power system, wherein an excessive electric power of the electric power system is charged, and the discharged electric power is used to compensate for the insufficient electric power of the electric power system. A power storage battery, voltage detection means for detecting a terminal voltage of the power storage battery, power level detection means for detecting an excess or deficiency level of power in the power system, and a power storage battery based on a detection result of the power level detection means. Charge / discharge command means for commanding the charge power / discharge power of the power storage battery, and when the terminal voltage of the power storage electrons detected by the voltage detection means reaches a predetermined upper limit, the terminal voltage of the power storage battery is set to the upper limit. Charge / discharge executing means for holding and otherwise charging / discharging the power storage battery in accordance with a command from the charge / discharge command means.

According to a fourth aspect of the present invention, the charging / discharging executing means according to the third aspect of the present invention is configured such that when the terminal voltage of the power storage battery detected by the voltage detecting means reaches a predetermined lower limit value, The terminal voltage of the storage battery is kept at the lower limit.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the embodiments, the principle of the power storage system according to the present invention will be described first. FIG. 1 is a diagram showing charge / discharge characteristics of a power storage battery used in this power storage system. As the power storage battery, a battery (a NAS battery, a lead battery, a redox flow battery, and the like) that performs charging and discharging by a chemical reaction is used as in the related art.

In FIG. 1, the charge and discharge characteristics of this power storage battery differ depending on the state of charge. The open terminal voltage VO (the terminal voltage V when the charge / discharge power is 0) increases as the state of charge of the battery increases, and the open terminal voltage VO decreases as the state of charge of the battery decreases.

As the discharge power PD of the battery increases, the terminal voltage V decreases. When the terminal voltage V becomes lower than the lower limit value VD, the terminal voltage V sharply decreases. When the battery is used in an overdischarge state in which the terminal voltage V is lower than the lower limit value VD, an insulating layer is formed on the surface of the electrode inside the battery, and the life of the battery is shortened.

Conversely, the terminal voltage V increases as the charging power PC of the battery increases, and when the terminal voltage V becomes higher than the upper limit value VU, the terminal voltage V sharply increases. Terminal voltage V
When the battery is used in an overcharged state higher than the upper limit value VU, the electrolyte inside the battery is decomposed, and the life of the battery is shortened.

Therefore, in the power storage system according to the present invention, the power storage battery is used such that its terminal voltage V falls within the range of VD to VU. For example, in the case where the charge state is high in the figure, when a command is issued to discharge power PD (> PD1) in which terminal voltage V falls below lower limit value VD, discharge power PD is held in PD1 and terminal voltage V is held. At the lower limit value VD. Further, when it is instructed to charge the power PC (> PC1) such that the terminal voltage V rises above the upper limit value VU, the charging power PC is held in the PC1 and the terminal voltage V is held in the upper limit value VU. When a command is issued to charge or discharge the power PC, PD such that the terminal voltage V becomes VD to VU, the commanded power PC, P
D is charged or discharged as it is.

Therefore, in the power storage system according to the present invention, the power storage battery is not overcharged or overdischarged, so that the life of the battery is prolonged. Also, when charging or discharging is commanded so as to cause overcharging or overdischarging, the maximum power that does not cause overcharging or overdischarging is charged or discharged in accordance with the open terminal voltage VO. And high system stabilization power can be obtained. Hereinafter, the power storage system according to the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of the power storage system according to one embodiment of the present invention. 2, this power storage system includes a control device 1, a power storage battery 8, and a DC / AC converter 9, and the control device 1
Includes a fluctuation detector 2, a compensation signal generator 3, a reference operation commander 4, an adder 5, a limiter 6, and a charge detector 7. This power storage system is, for example, a wind power generator 10
Is connected to a power supply line 11 receiving the generated power PW.

The fluctuation detector 2 is connected to the power supply line 11, detects the generated power PW of the wind power generator 10, generates a fluctuation detection signal PW 'having a level corresponding to the detected value, and generates a compensation signal. Give to Part 3. The signal PW 'fluctuates according to the rotation of the blades of the wind power generator 10, the fluctuation of the wind, and the like, as shown in FIG.

The compensation signal generator 3 extracts a fluctuation component of the signal PW ′ given from the fluctuation detector 2, generates a compensation signal H for compensating the fluctuation, and supplies it to the adder 5. The signal H is a signal obtained by removing the DC component from the signal PW ', as shown in FIG.

The reference operation command section 4 commands charging and discharging operations of the power storage battery 8 and the DC / AC converter 9 by the reference operation command signal B regardless of the generated power PW of the wind power generator 10. For example, the reference operation command section 4 commands the discharge of the battery 8 during the daytime when the power consumption is large, and instructs the charging of the battery 8 at midnight when the power consumption is small. In FIG. 3 (c), the signal B has a positive value until a certain time t0 and commands the battery 8 to be discharged. After that time t0, the signal B has a negative value and commands the battery 8 to be charged. .

The adder 5 adds the level of the signal H from the compensation signal generator 3 and the level of the signal B from the reference operation command section 4 to generate a charge / discharge command signal P, as shown in FIG. I do. The signal P is provided to the limiter 6. The charge amount detector 7 detects the open terminal voltage VO of the power storage battery 8, and supplies a signal VO ′ having a level corresponding to the detected value to the limiter 6.

The limiter 6 limits the level of the signal P in accordance with the level of the signal VO 'so that the power storage battery 8 is not overcharged or overdischarged. That is, the limiter 6
Stores the upper limit value Pa and the lower limit value -Pb of the signal P corresponding to each level of the signal VO ', as shown in FIGS.

When the state of charge is relatively high and the level of signal VO 'is high (VO' = V1), the upper limit Pa1 of signal P is relatively high and the lower limit of signal P is low, as shown in FIG. The value -Pb1 is relatively low. This corresponds to that in FIG. 1, when the state of charge is high, upper limit value PD1 of discharge power PD is relatively large, and lower limit value PC1 of charge power PC is relatively small.

When the state of charge is relatively low and the level of signal VO 'is low (VO' = V2), the upper limit Pa of signal P is relatively low, as shown in FIG. P
Is relatively high. This is shown in FIG.
When the state of charge is low, the upper limit value PD2 of the discharge power PD is relatively small, and the lower limit value PC2 of the charge power PC is relatively large.

The level of the output signal P 'of the limiter 6 is higher when the level of the signal P is higher than the upper limit Pa (Pa <P).
Is the upper limit Pa, and when the level of the signal P is lower than the lower limit Pb (P <−Pb), the lower limit is −Pb, and when the level of the signal P is between the upper limit Pa and the lower limit Pb (− Pb ≦ P ≦ Pa) becomes equal to the level of the signal P.
Therefore, as shown in FIGS. 3D and 3E, when the discharge is continuously commanded, the state of charge is reduced, the upper limit value Pa of the signal P is reduced, and the upper limit of the signal P 'is reduced. When charging is commanded continuously, the charging state rises and the signal P
, And the lower limit of the signal P ′ increases. Signal P ′ is provided to DC / AC converter 9.

The DC / AC converter 9 is provided between the power storage battery 8 and the power supply line 11, and charges and discharges the power storage battery 8 according to a signal P 'from the limiter 6. When the level of the signal P 'is positive, the DC voltage of the power storage battery 8 is converted by the DC / AC converter 9 into an AC voltage having a level corresponding to the signal P' and supplied to the power supply line 11.
When the level of the signal P 'is negative, the AC voltage of the power supply line 11 is converted by the DC / AC converter 9 into a DC voltage of a level corresponding to the signal P' and supplied to the power storage battery 8. DC / AC converter 9 is formed of, for example, a PWM control type inverter.

FIG. 5 is a flowchart showing the operation of the control device 1. The operation of the power storage system will be described with reference to FIG.

First, in step S 1, the fluctuation detector 2 generates a fluctuation detection signal PW ′ having a level corresponding to the generated power PW of the wind power generator 10. In step S 2, the compensation signal generator 3 converts the signal PW ′ into a direct current. The component is removed to generate the compensation signal H.

Next, in step S3, a reference operation command signal B is generated by the reference operation command section 4, and in step S4, the levels of the signals H and B are added by the adder 5 to generate a charge / discharge command signal P.

Then, in step S5, the open terminal voltage VO of the power storage battery 8 is detected by the charge amount detector 7, and a signal VO 'having a level corresponding to the detected value is generated. The signals P and VO 'are applied to a limiter 6.

In step S6, the limiter 6 outputs the signal VO '.
Upper limit value Pa and lower limit value of signal P based on the level of
Pb is read, and it is determined in step S7 whether or not the level of the signal P is lower than the lower limit value -Pb.
b) In step S8, the level of the signal P 'is set to -Pb.

The limiter 6 outputs the signal P in step S7.
Is determined to be higher than the lower limit value -Pb,
In step S9, it is determined whether or not the level of the signal P is higher than the upper limit Pa. If the level is higher (P> Pa), step S1
0, the level Pa of the signal P ′ is set, and when the level is low (−Pb ≦ P
.Ltoreq.Pa), the level of the signal P 'is
Level. Steps S <b> 1 to S <b> 11 are repeatedly performed in a cycle sufficiently shorter than the fluctuation of the generated power PW of the wind power generator 10. The signal P 'is supplied to the DC / AC converter 9
Given to.

When the level of the signal P 'is positive, the DC voltage of the power storage battery 8 is converted into an AC voltage by the DC / AC converter 9 and supplied to the power supply line 11, and the power of the power storage battery 8 is It is provided to the supply line 11. When the level of the signal P 'is negative, the AC voltage of the power supply line 11 is DC / A
The DC voltage is converted into a DC voltage by the C converter 9 and supplied to the power storage battery 8.
Given to. Therefore, the frequency and voltage of the power supply line 11 are stabilized, and the power system linked to the power supply line 11 is stabilized.

In this embodiment, the open terminal voltage VO of the power storage battery 8 is measured, and the state of charge of the power storage battery 8 is detected based on the measured value. However, the present invention is not limited to this. 8 is measured, and the terminal voltage V is corrected by an integrated value of the current value I and the internal resistance value R of the battery 8 to obtain an open terminal voltage VO = V−IR or VO = V + IR. You may ask. Alternatively, the charge power and the discharge power of the battery 8 may be integrated, and the state of charge of the power storage battery 8 may be detected from the integrated value. Further, the electrolyte of the battery 8 (for example, dilute sulfuric acid of a lead battery or the electrolyte of a redox flow battery) may be extracted and analyzed, and the state of charge of the power storage battery 8 may be detected based on the analysis result.

In this embodiment, the wind power generator 1
Although the generated power PW of 0 was detected and the battery 8 was charged and discharged based on the detection result, the present invention is not limited to this.
The frequency of the power system may be detected, and charging and discharging of the battery 8 may be performed based on the detection result.

FIG. 6 is a block diagram showing a configuration of a power storage system according to a modification of this embodiment.
It is a figure contrasted with. 6, this power storage system differs from the power storage system of FIG. 2 in that the limiter 6 and the charge amount detector 7 are replaced by a limiter 16 and a terminal voltage detector 17, respectively.

The terminal voltage detector 17 detects the terminal voltage V of the power storage battery 8, and supplies a signal V 'having a level corresponding to the detected value to the limiter 16. When the terminal voltage V of the power storage battery 8 reaches the lower limit value VD shown in FIG. 1 based on the signal V ′, the limiter 16 controls the level of the signal P so that the terminal voltage V is maintained at the lower limit value VD. When the terminal voltage V of the power storage battery 8 reaches the upper limit value VU shown in FIG. 1, the level of the signal P is controlled so that the terminal voltage V is maintained at the upper limit value VU. '. Therefore, also in this modified example, overcharging and overdischarging of the power storage battery 8 are prevented, and the use efficiency of the power storage battery 8 is increased.

It should be noted that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0038]

As described above, according to the first aspect of the invention, the state of charge of the power storage battery is detected, and the upper limit of the power to be charged in the power storage battery is set based on the detection result. When the specified charging power is larger than the set upper limit, the power of the upper limit is charged to the power storage battery, and otherwise, the power storage battery is charged and discharged as instructed. Therefore, it is possible to prevent the power storage battery from being overcharged, and to prolong the life of the battery. Further, when the instructed charging power exceeds the upper limit, the charging power is kept at the upper limit, so that the use efficiency of the battery is increased.

According to a second aspect of the present invention, in accordance with the first aspect, an upper limit value of the discharge power of the power storage battery is set based on the detection result of the state of charge of the power storage battery. If the power is larger than the set upper limit, the power of the upper limit is discharged from the power storage battery. Therefore, the power storage battery can be prevented from being over-discharged, and the battery life can be prolonged. Further, when the instructed discharge power exceeds the upper limit, the discharge power is maintained at the upper limit, so that the use efficiency of the battery is further increased.

In the invention according to claim 3, the terminal voltage of the power storage battery is detected, and when the detected value reaches a predetermined upper limit, the terminal voltage of the power storage battery is held at the upper limit, Otherwise, the power storage battery is charged and discharged as instructed. Therefore, it is possible to prevent the power storage battery from being overcharged, and to prolong the life of the battery. Further, when the terminal voltage of the power storage battery reaches the upper limit value, the terminal voltage is maintained at the upper limit value, so that the use efficiency of the battery is increased.

According to a fourth aspect of the present invention, when the detected value of the terminal voltage of the power storage battery reaches a predetermined lower limit, the terminal voltage of the power storage battery is reduced to the lower limit. To hold. Therefore, the power storage battery can be prevented from being over-discharged, and the battery life can be prolonged. In addition, when the terminal voltage of the power storage battery reaches the lower limit, the terminal voltage is maintained at the lower limit, so that the use efficiency of the battery is further increased.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the principle of a power storage system according to the present invention.

FIG. 2 is a block diagram showing a configuration of a power storage system according to one embodiment of the present invention.

FIG. 3 is a time chart illustrating an operation of the power storage system illustrated in FIG. 2;

FIG. 4 is a diagram for explaining the operation of the limiter shown in FIG. 2;

FIG. 5 is a flowchart illustrating an operation of the control device illustrated in FIG. 2;

FIG. 6 is a block diagram showing a modification of the embodiment.

FIG. 7 is a time chart showing an operation of a conventional power storage system.

[Explanation of symbols]

1, 1 'controller, 2 fluctuation detector, 3 compensation signal generator, 4 reference operation commander, 5 adder, 6, 16
Limiter, 7 Charge detector, 8 Power storage battery, 9
DC / AC converter, 10 wind power generator, 11 power supply line, 17 terminal voltage detector.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Nobuyuki Tokuda 3-3-22 Nakanoshima, Kita-ku, Osaka-shi, Osaka F-term in Kansai Electric Power Company (reference) 5G003 AA01 AA07 BA01 CA14 CC02 DA07 DA13 GB06 5G066 JA07 JB03

Claims (4)

[Claims] 1. An electric power storage system for stabilizing an electric power system, comprising: an electric power storage battery that is charged with excess electric power of the electric power system and compensates for the insufficient electric power of the electric power system with the discharged electric power. Charging state detecting means for detecting a charging state of the power storage battery; power level detecting means for detecting an excess or deficiency level of power of the power system; charging the power storage battery based on a detection result of the power level detecting means Charge / discharge command means for commanding power / discharge power, for setting an upper limit value of power to be charged in the power storage battery based on a detection result of the charge state detection means, to prevent overcharging of the power storage battery. Overcharge prevention means, and when the charging power instructed by the charge / discharge instruction means is larger than an upper limit value set by the overcharge prevention means, Charge the force to the power storage batteries,
In other cases, the power storage system includes charge / discharge execution means for charging / discharging the power storage battery in accordance with a command from the charge / discharge command means. 2. An over-discharge preventing means for setting an upper limit value of discharge power of the power storage battery based on a detection result of the charge state detecting means to prevent over-discharge of the power storage battery. The charging / discharging execution unit discharges the power of the upper limit from the power storage battery when the discharge power commanded by the charge / discharge command unit is larger than an upper limit value set by the overdischarge prevention unit. The power storage system according to claim 1. 3. An electric power storage system for stabilizing an electric power system, comprising: an electric power storage battery that is charged with excess electric power of the electric power system and compensates for the insufficient electric power of the electric power system with the discharged electric power; Voltage detection means for detecting a terminal voltage of the power storage battery; power level detection means for detecting an excess or deficiency level of power of the power system; charging power of the power storage battery based on a detection result of the power level detection means Charging / discharging command means for commanding power / discharge power, and when the terminal voltage of the power storage electrons detected by the voltage detecting means reaches a predetermined upper limit, the terminal voltage of the power storage battery is raised to the upper limit. A charge / discharge execution unit for charging / discharging the power storage battery in accordance with a command from the charge / discharge command unit otherwise. 4. The charging / discharging execution unit, when the terminal voltage of the power storage battery detected by the voltage detection unit reaches a predetermined lower limit, sets the terminal voltage of the power storage battery to the lower limit. The power storage system according to claim 3, wherein the power storage system holds the power.