Method and control device for operating a stationary, electric energy storage that is provided for an electric consumption unit

1. A method for operating an electric energy storage that is provided for an electric consumption unit, wherein the electric consumption unit is additionally coupled to an electric power grid and wherein the grid supplies electric power to the consumption unit under different supply conditions at different time periods and wherein a control device observes a state of charge of the energy storage and controls an electric power flow of the energy storage by way of an electric power converter, the method comprising the steps of:

providing different operation logics for controlling power flow as a function of the state of charge and as a function of a total unit load, wherein the total unit load is a net balance value of a power consumption in the consumption unit and an internal power delivery in the consumption unit;

observing a status signal that is signaling a present and/or a next supply condition of the grid;

selecting one of the operation logics as an active operation logic depending on a current value of the status signal; and

operating the power converter according to the active operation logic, wherein:

one of the supply conditions is an off-peak supply condition which is valid during off-peak periods and for the off-peak supply condition an off-peak operation logic is selected, which off-peak operation logic comprises:

upon determining that a time duration remaining until the end of the present off-peak period is shorter than or equal to a predefined stretched Final Charge Window, a positive power flow for charging the energy storage is set to a scaled value which is calculated such that the state of charge reaches a maximum level at the end of the off-peak period,

a Final Charge Window is a time value needed for charging the energy storage from its present state of charge to the maximum level, while a maximum converter power of the power converter is used, and

the stretched Final Charge Window is the Final Charge Window multiplied by a stretch factor a, with a greater than or equal to 1, wherein said scaled value is the maximum converter power divided by the stretch factor α.

2. The method according to claim 1 , wherein one of the supply conditions is a peak supply condition which is valid during peak periods and, for the peak supply condition, a peak operation logic is selected, which peak operation logic comprises:

upon determining that the total unit load is greater than 0, indicating a net power consumption, and that the state of charge is greater than a predefined peak threshold, a negative power flow is set for discharging the energy storage,

upon determining that the total unit load is smaller than 0, indicating a net power delivery:

in the case that net energy metering applies for the electric consumption unit, the power flow is set to 0 independently of the state of charge, and

in the case that net energy metering does not apply for the electric consumption unit, and the state of charge is below a predefined maximum level, a positive power flow is set for charging the energy storage.

3. The method according to claim 2 , wherein one of the supply conditions is a partial-peak supply condition which is valid during partial-peak periods and for the partial-peak supply condition a partial-peak operation logic is selected, which partial-peak operation logic comprises:

upon determining that the total unit load is greater than 0, indicating a net power consumption, and that the state of charge is greater than a predefined partial-peak threshold, a negative power flow is set for discharging the energy storage,

upon determining that the total unit load is smaller than 0, indicating a net power delivery, and that the state of charge is below the maximum level, a positive power flow is set for charging the energy storage.

4. The method according to claim 3 , wherein

the partial-peak threshold is adapted as a function of at least one count value that indicates a number of days where the peak threshold was reached during peak periods within a predefined observation period.

5. The method according to claim 4 , wherein

at least two count values are considered, each being valid for another observation period, and

the at least two count values are weighted by a weighting parameter β.

6. The method according to claim 5 , wherein the partial-peak threshold is adapted upon determining that the next period is a peak period, and otherwise the partial-peak threshold is set to the peak threshold upon determining that the next period is an off-peak period.

7. The method according to claim 4 , wherein the partial-peak threshold is adapted upon determining that the next period is a peak period, and otherwise the partial-peak threshold is set to the peak threshold upon determining that the next period is an off-peak period.

8. The method according to claim 1 , wherein for the off-peak operation logic:

upon determining that the time duration remaining until the end of the present off-peak period is greater than the stretched Final Charge Window, and that net energy metering applies for the electric consumption unit:

upon determining that the total unit load is greater than 0, indicating a net power consumption, the power flow is set to 0 independently of the state of charge, and

upon determining that the total unit load is smaller than 0, indicating a net power delivery, and that at the same time the state of charge is below maximum value, a positive power flow is set for charging the energy storage.

9. The method according to claim 8 , wherein

upon determining that no net energy metering applies, then:

upon determining that the total unit load is greater than 0, indicating a net power consumption, and that the state of charge is greater than a predefined off-peak threshold, a negative power flow is set for discharging the energy storage, and

upon determining that the total unit load is smaller than 0, indicating a net power delivery, and that the state of charge is below the maximum level, a positive power flow is set for charging the energy storage.

10. The method according to claim 9 , wherein

the off-peak threshold is adapted as a function of at least one count value that indicates a number of days where the partial-peak threshold was reached during partial-peak periods and/or the peak threshold was reached during peak periods within a predefined observation period.

11. The method according to claim 10 , wherein

at least two count values are considered, each being valid for another observation period, and the at least two count values are weighted by a weighting parameter γ.

12. The method according to claim 1 , wherein

the absolute value of the power flow is limited by both a maximum converter power of the power converter and the absolute value of the total unit load.

13. A control device for controlling an electric power flow of an electric energy storage, wherein the control device comprises a processing unit that is operatively configured to carry out the acts of:

providing different operation logics for controlling power flow as a function of the state of charge and as a function of a total unit load, wherein the total unit load is a net balance value of a power consumption in the consumption unit and an internal power delivery in the consumption unit;

observing a status signal that is signaling a present and/or a next supply condition of the grid;

selecting one of the operation logics as an active operation logic depending on a current value of the status signal; and

operating the power converter according to the active operation logic, wherein:

one of the supply conditions is an off-peak supply condition which is valid during off-peak periods and for the off-peak supply condition an off-peak operation logic is selected, which off-peak operation logic comprises:

upon determining that a time duration remaining until the end of the present off-peak period is shorter than or equal to a predefined stretched Final Charge Window, a positive power flow for charging the energy storage is set to a scaled value which is calculated such that the state of charge reaches a maximum level at the end of the off-peak period,

a Final Charge Window is a time value needed for charging the energy storage from its present state of charge to the maximum level, while a maximum converter power of the power converter is used, and

the stretched Final Charge Window is the Final Charge Window multiplied by a stretch factor a, with a greater than or equal to 1, wherein said scaled value is the maximum converter power divided by the stretch factor α.

14. A system, comprising:

an electric consumption unit,

an electric energy storage,

an electric power converter by which electric power flow to/from the electric energy storage; and

a control device comprises a processing unit that is operatively configured to carry out the acts of:

providing different operation logics for controlling power flow as a function of a state of charge of the energy store and as a function of a total unit load, wherein the total unit load is a net balance value of a power consumption in the consumption unit and an internal power delivery in the consumption unit;

observing a status signal that is signaling a present and/or a next supply condition of the grid;

selecting one of the operation logics as an active operation logic depending on a current value of the status signal; and

operating the power converter according to the active operation logic, wherein:

one of the supply conditions is an off-peak supply condition which is valid during off-peak periods and for the off-peak supply condition an off-peak operation logic is selected, which off-peak operation logic comprises:

upon determining that a time duration remaining until the end of the present off-peak period is shorter than or equal to a predefined stretched Final Charge Window, a positive power flow for charging the energy storage is set to a scaled value which is calculated such that the state of charge reaches a maximum level at the end of the off-peak period,

a Final Charge Window is a time value needed for charging the energy storage from its present state of charge to the maximum level, while a maximum converter power of the power converter is used, and

the stretched Final Charge Window is the Final Charge Window multiplied by a stretch factor a, with a greater than or equal to 1, wherein said scaled value is the maximum converter power divided by the stretch factor α.