Method and system for allocating a power request to a plurality of batteries connected in parallel
The invention relates to a method and a system for allocating a power request P REQ to a plurality of batteries connected in parallel in an electrical energy storage system. According to the invention, the allocation system comprises a global control system that can determine a combination of batteries from said plurality of batteries, which is optimized to respond to the power request using the highest possible number of batteries, and allocate a power level to each of the batteries of said optimized combination.
1. A method for allocating a power request P REQ to a plurality of batteries connected in parallel to operate to meet the power request, the method including:
determining a combination of batteries, from said plurality of batteries, that is optimized to meet the power request by using the greatest possible number of batteries, said determining including:
calculating a first sum of a minimum power required to operate for all of the batteries of a group including said plurality of batteries,
when the first sum is less than the power request, selecting all of the batteries of said group to operate,
when the first sum is greater than the request, removing a battery from the group and calculating a second sum of the minimum power required to operate for all of the batteries remaining in the group,
when the second sum is less than the power request, selecting all of the batteries remaining in said group to operate, and
when the second sum is greater than the request, successively removing batteries from the group until a sum of the minimum power required to operate for all of the batteries remaining in the group to operate is less than the power request; and
allocating a portion of the power request Pi to be supplied by each of the batteries i of said optimized combination according to the relationship:
P ( i )= P min ( i )+( M ( i )/Σ M ( i ))*( P REQ −ΣP min ( i ))
in which P min (i) is the minimum power required to operate the battery i, M(i) is a difference between a maximum power possible for the battery i and the minimum power required to operate the battery i, and P REQ is the power request.
2. The method as claimed in claim 1 , wherein the batteries are removed successively in decreasing order of their associated minimum operating power.
3. The method as claimed in claim 1 , wherein the determining includes a preliminary sub-step of prioritization in which one or more batteries, termed priority batteries, of the plurality of batteries form part of the optimized combination.
4. The method as claimed in claim 1 , further comprising, prior to the determining, comparing the power request P REQ with the minimum power required for the batteries to operate.
5. The method as claimed in claim 4 , wherein said comparing includes determining whether the following relationship is satisfied:
P REQ >Min( P min ( i ))
where P min (i) is the minimum power required for a battery i to operate.
6. A system for allocating a power request P REQ to a plurality of batteries, connected in parallel, of an electrical energy storage system to operate to meet the power request, including an overall control system configured to:
determine a combination of batteries, from said plurality of batteries, that is optimized to meet the power request by using the greatest possible number of batteries; and
allocate a portion of the power request Pi to be supplied by each of the batteries i of said optimized combination according to the relationship:
P ( i )= P min ( i )+( M ( i )/Σ M ( i ))*( P REQ −ΣP min ( i ))
in which P min (i) is the minimum power required to operate the battery i, M(i) is a difference between a maximum power possible for the battery i and the minimum power required to operate the battery i P REQ is the power request,
wherein, in order to determine the combination of batteries, the overall control system is configured to:
calculate a first sum of a minimum power required to operate for all of the batteries of a group including said plurality of batteries,
when the first sum is less than the power request, select all of the batteries of said group to operate,
when the first sum is greater than the request, remove a battery from the group and calculating a second sum of the minimum power required to operate for all of the batteries remaining in the group,
when the second sum is less than the power request, select all of the batteries remaining in said group to operate, and
when the second sum is greater than the request, successively remove batteries from the group until a sum of the minimum power required to operate for all of the batteries remaining in the group to operate is less than the power request.