Method and apparatus for managing ultracapacitor energy storage systems for a power transmission system

• US 7,633,284 B2
• Filed: 03/08/2006
• Issued: 12/15/2009
• Est. Priority Date: 03/08/2005
• Status: Expired due to Fees

• Current Assignee: Tennessee Valley Authority (Government of the United States of America)
• Original Assignee: Tennessee Valley Authority (Government of the United States of America)
• Inventors: Geist, Thomas D., Bradshaw, Dale T., Ingram, Michael R., Kamath, Haresh, Bunton, Scott, Nastasi, Doni, Mansoor, Arshad
• Primary Examiner(s): He; Amy
• Application Number:
  US11/276,629
• Publication Number:
  US 20060241876A1
• Time in Patent Office: 1,378 Days
• Field of Search: 324/76.11, 324/537, 324/426, 320/167
• US Class Current: 324/76.11
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/0019 using switched or multiplexed charge circuits
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/005 Detection of state of health [SOH]
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices

Abstract

A method and apparatus for automatically monitoring and controlling various parameters of individual ultracapacitor cells in a series string of such cells. These parameters are monitored, and a replacement charge current is delivered to any cell which has lost charge due to discharge either external or internal to the cell. Also, the application of this method and apparatus to energy storage systems for an electrical power transmission grid.

Claims

1. A method for monitoring and controlling various parameters of individual ultracapacitor cells or group of ultracapacitor cells in a string of ultracapacitors, said method comprising the steps of:

selectively monitoring, with a charge and monitoring circuit, various parameters, which include at least one of voltage, current, temperature, DC resistance, AC impedance, and capacity, for individual ultracapacitor cells of a string, or combinations of ultracapacitor cells within a string, or an entire string of ultracapacitor cells, and selectively delivering charge current to any individual cell or group of cells in the string, to replace charge lost due to discharge either external or internal to the ultracapacitor cell;

selectively making, via a cell selector comprising an arrangement of switches appropriate positive or negative connections from the terminals of the ultracapacitor cell, group of ultracapacitor cells, or string of ultracapacitor cells to said charge and monitoring circuit;

controlling, via a local controller comprising a microprocessor, the charging and monitoring parameters of the charge and monitoring circuit according to signals from a central processor,

wherein the local controller sets other functional parameters of the charge and monitoring circuit, including at least one of switching frequency, voltage setpoints, current setpoints, temperature setpoints, and other parameters;

allowing, via a signal conditioning circuit, signal transfer between the monitoring circuit and cell selector and the central processor while maintaining optical voltage isolation between them;

providing the central processor which, through the signal conditioning circuit, controls the cell selector to select individual ultracapacitor cells or groups of ultracapacitor cells according to software instructions, transmits data to and receives data from the charge and monitoring circuit, and controls the operation of the charge and monitoring circuit, and

providing the central processor with;

data storage allowing the recording of data from the various ultracapacitor cells or groups of ultracapacitor cells;

communication ports that allow the central processor to interact with other systems for analysis, acknowledgement of alarms, and control of all functions; and

software that defines how ultracapacitor cells or groups of ultracapacitor cells must be monitored and controlled.

2. The method of claim 1, wherein critical parameters of individual cells of a string, or combinations of cells within a string, or an entire string are monitored, said parameters comprising of voltage, current, temperature, DC resistance, AC impedance, and capacity.

3. The method of claim 1, wherein the voltages of two or more cells in series are balanced.

4. The method of claim 1, further comprising providing a software algorithm which detects and annunciates cell health conditions including at least one of open circuit, short circuit, and loss of electrolyte.

5. The method of claim 1, further comprising providing a software algorithm which adjusts at least one of maximum and minimum cell, module, and string voltage as a function of charge and discharge rate.

6. The method of claim 1, further comprising providing a software algorithm which adjusts charge current as a function of cell, or module, or string voltage.

7. The method of claim 1, further comprising providing an isolated device for measurement of at least one of charge and discharge current for either cells, or modules, or strings.

8. The method of claim 1, which further comprises providing an isolated communication system that allows one central processor to electronically communicate with one or more local controllers, each local controller controlling some subsection of cells, and whose operating voltages are not referenced to the same point as that of the central processor.

9. The method of claim 8, which further comprises preventing overcharging and undercharging of individual cells, or modules, or strings.

10. The method of claim 1, further comprising providing a cell selection mechanism that allows for charging or discharging of particular cells, or modules, or strings, separately from other cells, modules, or strings.

11. The method of claim 8, wherein said controlling by the sub-processors is performed in such a way as to allow a neutral state so that isolation from the cells, modules, or strings can be detected and verified.

12. The method of claim 10, further comprising preventing the shorting of one or more cells, modules, or strings in the event of a failure of the cell selection mechanism.

14. The method of claim 1, further comprising supplying charging current to said ultracapacitors using a microprocessor-controlled variable-output power supply acting in a current-source mode.

13. An apparatus for monitoring and controlling various parameters of individual ultracapacitor cells or group of ultracapacitor cells in a string of ultracapacitors, said apparatus comprising:

at least one charge and monitoring circuit for selectively monitoring various parameters, which include at least one of voltage, current, temperature, DC resistance, AC impedance, and capacity, for individual ultracapacitor cells of a string, or combinations of ultracapacitor cells within a string, or an entire string of ultracapacitor cells, and for selectively delivering charge current to any individual ultracapacitor cell or group of ultracapacitor cells in the string, to replace charge lost due to discharge either external or internal to the ultracapacitor cell;

at least one cell selector comprising an arrangement of switches that selectively makes appropriate positive or negative connections from the terminals of the ultracapacitor cell, group of ultracapacitor cells, or string of ultracapacitor cells to said charge and monitoring circuit;

a local controller comprising a microprocessor that controls the charging and monitoring parameters of the charge and monitoring circuit according to signals from a central processor,

wherein the local controller includes means for setting other functional parameters of the charge and monitoring circuit, including at least one of switching frequency, voltage setpoints, current setpoints, temperature setpoints, and other parameters;

a signal conditioning circuit that allows signal transfer between the monitoring circuit and cell selector and the central processor while maintaining optical voltage isolation between them; and

the central processor which, through the signal conditioning circuit, controls the cell selector to select individual ultracapacitor cells or groups of ultracapacitor cells according to software instructions, transmits data to and receives data from the charge and monitoring circuit, and controls the operation of the charge and monitoring circuit,

wherein the central processor includes;

data storage allowing the recording of data from the various cells or groups of cells;

communication ports that allow the central processor to interact with other systems for analysis, acknowledgement of alarms, and control of all functions; and

software that defines how cells or groups of cells must be monitored and controlled.

15. The apparatus of claim 13, further comprising a microprocessor-controlled variable-output power supply acting in a current-source mode which supplies charging current to said ultracapacitors.