Control system for electric storage system

Patent metadata

Field	Value
Publication number	US-10141751-B2
Application number	US-201415116583-A
Country	US
Kind code	B2
Filing date	Sep 22, 2014
Priority date	Feb 26, 2014
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

A control system for an electric storage system, in which a plurality of pairs of storage batteries and converters are connected in parallel to a power system, includes: a unit that decides charge and discharge of total power by the pairs of storage batteries and converters; and a unit that distributes the charge and discharge power decided by the charge and discharge power decision unit to the pairs of storage batteries and converters. The power distribution decision unit compares the charge and discharge total power with a limit output when conversion efficiency of the converters is equal to or greater than standard efficiency, and decides a running number by which an output of all the pairs of running storage batteries and converters is equal to or greater than the limit output when the charge and discharge total power is equal to or greater than the limit output.

First claim

The invention claimed is:

1. A control system to control an electric storage system in which a plurality of pairs of storage batteries and converters are connected in parallel to a power system, comprising:
a controller configured to control a charge total power received by the plurality of pairs of storage batteries and converters,
wherein a total number of the plurality of pairs of storage batteries and converters is N, and N is ≥2,
wherein the controller is configured to:
compare the charge total power (P) to be received by the plurality of pairs of storage batteries and converters with a limit output (p 0 ) corresponding to a predetermined conversion efficiency of a first pair of the storage batteries and converters
when p 0 ≤P≤N×p 0 , determine an operation number (n) of the pairs of storage batteries and converters which are to operate to receive the P in parallel, where n is equal to an integer quotient of P/p 0 , and
wherein the controller is further configured to:
determine respective charge powers (P i ) of each of the n pairs of storage batteries and converters for a charge operation based on respective states of charge (SOC i ) of each of the n pairs of storage batteries and converters and a predetermined upper limit charge amount (SOC max ).

2. The control system to control the electric storage system according to claim 1 ,
wherein the controller is further configured to:
determine a plurality of first coefficients α i such that α i =(SOC max −SOC i )/sum(SOC max −SOC i ) where P i =α i ×P and sum(α i )=1.

3. The control system to control the electric storage system according to claim 2 ,
wherein the α i are different for the n pairs of storage batteries and converters.

4. The control system to control the electric storage system according to claim 2 ,
wherein respective predetermined life magnification values (y i ) are set for each of the N pairs of storage batteries and converters, and
wherein the controller is further configured to:
determine a plurality of second coefficients β i such that β i =(y i ×sum(1/y i )) −1 where P i =β i ×P and sum(β i )=1.

5. The control system to control the electric storage system according to claim 2 ,
wherein respective predetermined life magnification values (y i ) are set for each of the N pairs of storage batteries and converters, and
wherein the controller is further configured to:
determine a plurality of second coefficients β i such that β i =(y i 2 ×sum(1/y i 2 )) −1 where P i =β i ×P and sum(β i )=1.

6. The control system to control the electric storage system according to claim 4 ,
wherein the controller is further configured to:
select the smaller of the first and second coefficients α i and β i to determine the respective P i of each of the n pairs of storage batteries and converters for the charge operation, and
control the n pairs of storage batteries and converters to receive the charge powers P i in parallel so that the charge total power P is received by the n pairs of storage batteries and converters.

7. The control system to control the electric storage system according to claim 5 ,
wherein the controller is further configured to:
select the smaller of the first and second coefficients α i and β i to determine the respective P i of each of the n pairs of storage batteries and converters for the charge operation, and
control the n pairs of storage batteries and converters to receive the charge powers P i in parallel so that the charge total power P is received by the n pairs of storage batteries and converters.

8. A control system to control an electric storage system in which a plurality of pairs of storage batteries and converters are connected in parallel to a power system, comprising:
a controller configured to control a discharge total power output by the plurality of pairs of storage batteries and converters,
wherein a total number of the plurality of pairs of storage batteries and converters is N, and N is ≥2,
wherein the controller is configured to:
compare the discharge total power (P) to be output by the plurality of pairs of storage batteries and converters with a limit output (P 0 ) corresponding to a predetermined conversion efficiency of a first pair of the storage batteries and converters,
when p 0 ≤P≤N×p 0 , determine an operation number (n) of the pairs of storage batteries and converters which are to operate to output the P in parallel, where n is equal to an integer quotient of P/p 0 , and
wherein the controller is further configured to:
determine respective discharge powers (P i ) of each of the n pairs of storage batteries and converters for a discharge operation based on respective states of charge (SOC i ) of each of the n pairs of storage batteries and converters and a predetermined lower limit charge amount (SOC min ).

9. The control system to control the electric storage system according to claim 8 ,
wherein the controller is further configured to:
determine a plurality of first coefficients α i such that α i =(SOC i −SOC min )/sum(SOC i −SOC min ).

10. The control system to control the electric storage system according to claim 9 ,
wherein the α i are different for the n pairs of storage batteries and converters.

11. The control system to control the electric storage system according to claim 9 ,
wherein respective predetermined life magnification values (y i ) are set for each of the N pairs of storage batteries and converters, and
wherein the controller is further configured to:
determine a plurality of second coefficients β i such that β i =(y i ×sum(1/y i )) −1 where P i =β i ×P and sum(β i )=1.

12. The control system to control the electric storage system according to claim 9 ,
wherein respective predetermined life magnification values (y i ) are set for each of the N pairs of storage batteries and converters, and
wherein the controller is further configured to:
determine a plurality of second coefficients β i such that β i =(y i 2 ×sum(1/y i 2 )) −1 where P i =β i ×P and sum(β i )=1.

13. The control system to control the electric storage system according to claim 11 ,
wherein the controller is further configured to:
select the smaller of the first and second coefficients α i and β i to determine the respective P i of each of the n pairs of storage batteries and converters for the charge operation, and
control the n pairs of storage batteries and converters to output the discharge powers P i in parallel so that the discharge total power P is output by the n pairs of storage batteries and converters.

14. The control system to control the electric storage system according to claim 12 ,
wherein the controller is further configured to:
select the smaller of the first and second coefficients α i and β i to determine the respective P i of each of the n pairs of storage batteries and converters for the charge operation, and
control the n pairs of storage batteries and converters to output the discharge powers P i in parallel so that the discharge total power P is output by the n pairs of storage batteries and converters.

Assignees

• Hitachi Ltd

Inventors

• Arita Hiroshi
• Inoue Hideki
• Akatsu Tooru
• Toyota Masashi

Classifications

• H02J4/25

  for transfer of electric power between AC and DC networks, e.g. for supplying the DC section within a load from an AC mains system · CPC title

• H02J7/50

  acting upon multiple batteries simultaneously or sequentially · CPC title

• H02J7/56

  Active balancing, e.g. using capacitor-based, inductor-based or DC-DC converters · CPC title

• H02J7/52

  for charge balancing, e.g. equalisation of charge between batteries · CPC title

• H01M10/482

  for several batteries or cells simultaneously or sequentially · CPC title