METHOD OF CONTROLLING CHARGING AND DISCHARGING OF BATTERY ENERGY STORAGE DEVICE AND THE BATTERY ENERGY STORAGE DEVICE FOR THE SAME

• US 20150214754A1
• Filed: 12/12/2014
• Published: 07/30/2015
• Est. Priority Date: 01/27/2014
• Status: Active Grant

• Current Assignee: LSIS Co. Ltd. (LS Corporation)
• Original Assignee: LSIS Co. Ltd. (LS Corporation)
• Inventors: CHOI, Eun Sik, LEE, YUN JAE
• Granted Patent: US 9,634,510 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: H02J 3/242 using phasor measuring units [PMU]
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/0069 Charging or discharging for charge maintenance, battery initiation or rejuvenation
• CPC Class Codes: H02J 7/007 Regulation of charging or discharging current or voltage
• CPC Class Codes: H02J 7/00712 the cycle being controlled or terminated in response to electric parameters
• CPC Class Codes: Y02E 40/10 Flexible AC transmission systems [FACTS]
• CPC Class Codes: Y02E 40/70 Smart grids as climate change mitigation technology in the energy generation sector
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/22 Flexible AC transmission systems [FACTS] or power factor or reactive power compensating or correcting units

Abstract

A method of charging and discharging battery energy storage device is provided. The method includes measuring a voltage and a frequency of a grid, measuring a state of charge (SOC) value of a battery, calculating an SOC offset value and an SOC feedback gain value from the measured SOC value of the battery, and performing a voltage droop control based on the voltage of the grid and a frequency droop control on the basis of the frequency of the grid, the SOC offset value and the SOC feedback gain value and controlling charging and discharging of the battery.

Claims

1. A method of charging and discharging battery energy storage device, comprising:

measuring a voltage and a frequency of a grid;

measuring a state of charge (SOC) value of a battery;

calculating an SOC offset value and an SOC feedback gain value from the measured SOC value of the battery; and

performing a voltage droop control based on the voltage of the grid and a frequency droop control on the basis of the frequency of the grid, the SOC offset value and the SOC feedback gain value and controlling charging and discharging of the battery.

2. The method according to claim 1, wherein the controlling of the charging and discharging comprises adjusting a charging period and a discharging period of an entire period on the basis of the SOC offset value.

3. The method according to claim 2, wherein the SOC offset value is calculated according to the following equation:

4. The method according to claim 3, wherein the SOCref is a median value 50% of the SOC, and

when the SOC is 50%, the SOC offset value becomes 0,

when the SOC is between 0% and 50%, an absolute value of the SOC offset value increases as the SOC approaches 0% in a state where the SOC offset value has a positive value, and

when the SOC value is between 50% and 100%, the absolute value of the SOC offset value increases as the SOC approaches 100% in a state where the SOC offset value has a negative value.

5. The method according to claim 1, wherein the controlling of the charging and discharging comprises adjusting a charging amount and a discharging amount on the basis of the SOC feedback gain value.

6. The method according to claim 5, wherein the SOC feedback gain value is calculated by the following equation:

7. The method according to claim 1, wherein the controlling of the charging and discharging comprises:

operating the SOC offset value to a grid target power value set in the grid and outputting a first operation result;

operating a frequency droop coefficient to a frequency difference between a reference frequency of the grid and a measured frequency of the grid and outputting a second operation result;

operating the SOC feedback gain value to the frequency droop coefficient operation result and outputting a second operation result;

operating the second operation result to the first operation result and outputting a reference power value; and

obtaining a difference between the reference power value and a power value of the grid and performing a charging and discharging control.

8. The method according to claim 1, wherein the controlling of the charging and discharging comprises:

operating a frequency droop coefficient to a frequency difference between a reference frequency of the grid and a measured frequency of the grid;

operating the SOC feedback gain value to the frequency droop coefficient operation result and outputting a first operation result;

operating the first operation result to the grid target power value set to the grid and outputting a second operation result;

operating the SOC offset value to the second operation result and outputting a reference power value; and

obtaining a difference between the reference power value and the grid power value and controlling the charging and discharging.

9. The method according to claim 1, wherein the controlling of the charging and discharging comprises:

operating a frequency droop coefficient to a frequency difference value between a reference frequency of the grid and the measured frequency of the grid;

operating the SOC feedback gain value to the frequency droop coefficient operation result and outputting a first operation result;

operating the SOC offset value and the first operation result and outputting a second operation result;

operating the second operation result to the grid target power value set to the grid and outputting a reference power value; and

obtaining a difference value between the reference power value and a power value of the grid and performing a charging and discharging control.

10. A battery energy storage device comprising:

a battery;

a data storage unit storing data necessary for a voltage droop control and a frequency droop control for the battery;

an SOC measuring unit measuring an SOC value of the battery;

a grid voltage and frequency measuring unit measuring a voltage and a frequency of the grid;

a charging and discharging control unit performing the voltage droop control and frequency droop control corresponding to the voltage and frequency of the grid by using the data stored in the data storage unit, and an SOC offset value and an SOC feedback gain value of the battery, which are calculated on the basis of the SOC value, and outputting a control signal for performing charging and discharging on the battery while preventing overcharging and over-discharging at the time of charging and discharging the battery; and

a charging and discharging unit charging or discharging the battery according to the control signal for performing charging and discharging of the charging and discharging control unit.

11. The battery energy storage device according to claim 10, wherein the data storage unit stores a voltage droop control coefficient, a frequency droop control coefficient, a reference SOC value of the battery, a reference voltage value of the grid, a reference frequency value of the grid, a target power value of the grid.