Frequency regulation method, frequency regulation apparatus, and storage battery system

• US 9,692,243 B2
• Filed: 11/19/2013
• Issued: 06/27/2017
• Est. Priority Date: 11/19/2013
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Stearns, Hoday, Kaji, Mitsuru, Watanabe, Kenichi
• Primary Examiner(s): LIN, SUN J
• Application Number:
  US14/440,925
• Publication Number:
  US 20160013676A1
• Time in Patent Office: 1,316 Days
• Field of Search: 320134
• CPC Class Codes: H02J 13/00002 characterised by monitoring
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/14 Energy storage units
• CPC Class Codes: Y04S 10/30 State monitoring, e.g. fault, temperature monitoring, insulator monitoring, corona discharge

Abstract

Provided is a frequency regulation method for regulating a frequency of a power system so that the frequency approximates to a rated frequency, the method including: measuring the frequency; obtaining an SOC (state of charge) of a storage battery; determining a base-point of power to be charged in or discharged from the storage battery when the measured frequency is equal to a predetermined rated frequency; determining a control variable changed from the base-point by an amount corresponding to a frequency deviation that is a difference between the predetermined rated frequency and the measured frequency; and charging or discharging the storage battery based on the control variable, wherein in the determining a base-point, a third rate of change is smaller than a first rate of change and a second rate of change that are average rates of change in the base-point with respect to the SOC when the SOC is within a first range and a second range, respectively.

Claims

1. A frequency regulation method for regulating a frequency of a power system by charging or discharging a storage battery, the method comprising:

measuring the frequency;

obtaining an SOC (state of charge) of the storage battery;

determining a base-point indicating a value of power to be charged in or discharged from the storage battery when the measured frequency is equal to a predetermined rated frequency;

determining a charge control variable or a discharge control variable that is a power value changed from the base-point by an amount corresponding to a frequency deviation that is a difference between the predetermined rated frequency and the measured frequency to generate the charge control variable or the discharge control variable; and

charging or discharging the storage battery based on the charge control variable or the discharge control variable,

wherein in the determining a base-point;

the base-point is determined to be equal to a charging power value when the SOC of the storage battery is within a first range smaller than a first threshold, the charging power value indicating power that is being charged in the storage battery;

the base-point is determined to be equal to a discharging power value when the SOC of the storage battery is within a second range larger than a second threshold larger than the first threshold, the discharging power value indicating power that is being discharged from the storage battery;

the base-point is changed according to the SOC of the storage battery; and

a third rate of change is smaller than a first rate of change and a second rate of change, the first rate of change being an average rate of change in the base-point with respect to the SOC when the SOC is within the first range, the second rate of change being an average rate of change in the base-point with respect to the SOC when the SOC is within the second range, the third rate of change being an average rate of change in the base-point with respect to the SOC when the SOC is within a third range from the first threshold to the second threshold.

2. The frequency regulation method according to claim 1,

wherein in the determining a base-point, the base-point is determined to be 0 when the obtained SOC is within the third range.

3. The frequency regulation method according to claim 1,

wherein the first threshold ranges from 0 to 50% of a full capacity of the storage battery, and

the second threshold ranges from 50% to 100% of the full capacity of the storage battery.

4. The frequency regulation method according to claim 1,

wherein the predetermined rated frequency is a moving average of a plurality of frequencies measured in a previous predetermined period.

5. The frequency regulation method according to claim 4, further comprising

determining an operating range indicating a maximum range within which an amount of charge or discharge is increased with respect to the base-point,

wherein in the determining a charge control variable or a discharge control variable, the charge control variable or the discharge control variable is determined to be closer to a maximum charge value as an absolute value of the frequency deviation increases, when the frequency deviation is larger than 0, the maximum charge value being a value obtained by adding the operating range to the base-point, and

the charge control variable or the discharge control variable is determined to be closer to a maximum discharge value as the absolute value of the frequency deviation increases, when the frequency deviation is smaller than 0, the maximum discharge value being a value obtained by subtracting the operating range from the base-point.

6. The frequency regulation method according to claim 1,

wherein the predetermined rated frequency is a standard frequency defined for the power system.

7. The frequency regulation method according to claim 1,

wherein in the determining a base-point, a base-point is newly determined each time when the charge control variable or the discharge control variable is generated.

8. The frequency regulation method according to claim 1,

wherein in the obtaining an SOC, SOCs are obtained at predetermined times, and

in the determining a base-point, a base-point is newly determined when the SOC obtained in the obtaining an SOC is different from each of the SOCs obtained at the predetermined times by a predetermined value or more.

9. The frequency regulation method according to claim 1,

wherein in the obtaining an SOC, a percentage of the SOC within a range out of a total capacity of the storage battery is obtained as the SOC.

10. A frequency regulation apparatus that regulates a frequency of a power system by charging or discharging a storage battery, the apparatus comprising:

a frequency measuring unit configured to measure the frequency;

a charge obtainment unit configured to obtain an SOC (state of charge) of the storage battery;

a base-point determining unit configured to determine a base-point indicating a value of power to be charged in or discharged from the storage battery when the measured frequency is equal to a predetermined rated frequency;

a control variable determining unit configured to generate a charge control variable or a discharge control variable that is a power value changed from the base-point by an amount corresponding to a frequency deviation that is a difference between the predetermined rated frequency and the measured frequency; and

a charge/discharge control unit configured to charge or discharge the storage battery based on the charge control variable or the discharge control variable,

wherein the base-point determining unit is configured to;

determine the base-point to be equal to a charging power value when the SOC of the storage battery is within a first range smaller than a first threshold, the charging power value indicating power that is being charged in the storage battery;

determine the base-point to be equal to a discharging power value when the SOC of the storage battery is within a second range larger than a second threshold larger than the first threshold, the discharging power value indicating power that is being discharged from the storage battery; and

change the base-point according to the SOC of the storage battery, and

a third rate of change is smaller than a first rate of change and a second rate of change, the first rate of change being an average rate of change in the base-point with respect to the SOC when the SOC is within the first range, the second rate of change being an average rate of change in the base-point with respect to the SOC when the SOC is within the second range, the third rate of change being an average rate of change in the base-point with respect to the SOC when the SOC is within a third range from the first threshold to the second threshold.

11. A storage battery system comprising:

the frequency regulation apparatus according to claim 10; and

the storage battery.