Energy storage controller with battery life model
An electrical energy storage system includes a battery configured to store and discharge electric power to an energy grid, a power inverter configured to use battery power setpoints to control an amount of the electric power stored or discharged from the battery, the battery power setpoints comprising at least one of frequency regulation power setpoints and ramp rate control power setpoints, and a controller. The controller is configured to use a battery life model to generate the battery power setpoints for the power inverter. The battery life model includes one or more variables that depend on the battery power setpoints.
1. An electrical energy storage system comprising:
a battery configured to store electric power and discharge electric power to an energy grid;
a power inverter configured to control an amount of the electric power stored to or discharged from the battery; and
a controller configured to determine battery power setpoints for the power inverter based on a battery life model, the battery life model operable to estimate a cost of battery degradation that will result from the battery power setpoints, the battery life model operable to estimate a loss in battery capacity as a sum of a plurality of piecewise functions and a nominal loss,
wherein the plurality of piecewise functions depend on a cell temperature, a state-of-charge, and a depth of discharge.
2. The system of claim 1 , wherein the cell temperature is measured by a temperature sensor configured to measure a temperature of the battery.
3. The system of claim 1 , wherein the cell temperature is estimated by a predictive model based on a battery power and an ambient temperature.
4. The system of claim 1 , wherein the state-of-charge is measured at the end of a frequency response period.
5. The system of claim 1 , wherein the depth of discharge is based on a difference of a maximum state-of-charge and a minimum state-of-charge.
6. The system of claim 5 , wherein the maximum state-of-charge and the minimum state-of-charge are measured over a frequency response period.
7. The system of claim 1 , wherein the plurality of piecewise functions further depend on an average power ratio, wherein the average power ratio is a ratio of an average power output of the battery to a designed power of the battery.
8. The system of claim 1 , wherein the plurality of piecewise functions further depend on an average effort ratio, wherein the average effort ratio is a ratio of an average change in battery power to a designed power of the battery.
9. The system of claim 1 , wherein the nominal loss is an expected loss in capacity of the battery over a given amount of time.
10. An electrical energy storage system comprising:
a battery configured to store electric power and discharge electric power to an energy grid;
a power inverter configured to control an amount of the electric power stored to or discharged from the battery; and
a controller configured to determine battery power setpoints for the power inverter based on a battery life model the battery life model operable to estimate a cost of battery degradation that will result from the battery power setpoints, the battery life model operable to estimate a loss in battery capacity as a sum of a parametric function and a nominal loss,
wherein the parametric function depends on a cell temperature, a state-of-charge, and a depth of discharge.
11. The system of claim 10 , wherein the cell temperature is measured by a temperature sensor configured to measure a temperature of the battery.
12. The system of claim 10 , wherein the cell temperature is estimated by a predictive model based on a battery power and an ambient temperature.
13. The system of claim 10 , wherein the state-of-charge is measured at the end of a frequency response period.
14. The system of claim 10 , wherein the depth of discharge is based on a difference of a maximum state-of-charge and a minimum state-of-charge.
15. The system of claim 14 , wherein the maximum state-of-charge and the minimum state-of-charge are measured over a frequency response period.
16. The system of claim 10 , wherein the parametric function further depends on an average power ratio, wherein the average power ratio is a ratio of an average power output of the battery to a designed power of the battery.
17. The system of claim 10 , wherein the parametric function further depends on an average effort ratio, wherein the average effort ratio is a ratio of an average change in battery power to a designed power of the battery.
18. The system of claim 10 , wherein the nominal loss is an expected loss in capacity of the battery over a given amount of time.
19. A method of operating an electrical energy storage system, the electrical energy storage system including a battery, a power inverter, and a controller, the method comprising:
storing electric power to the battery and discharging electric power from the battery to an energy grid;
controlling an amount of the electric power stored to the battery or discharged from the battery to the energy grid;
determining, by the controller, battery power setpoints for the power inverter based on a battery life model;
estimating, using the battery life model, a cost of battery degradation that will result from the battery power setpoints;
estimating, using the battery life model, a loss in battery capacity as a sum of a plurality of piecewise functions and a nominal loss,
wherein the plurality of piecewise functions depend on a cell temperature, a state-of-charge, and a depth of discharge.
20. A method of operating an electrical energy storage system, the electrical energy storage system including a battery, a power inverter, and a controller, the method comprising:
storing electric power to the battery and discharging electric power from the battery to an energy grid;
controlling an amount of the electric power stored to the battery or discharged from the battery to the energy grid;
determining, by the controller, battery power setpoints for the power inverter based on a battery life model;
estimating, using the battery life model, a cost of battery degradation that will result from the battery power setpoints;
estimating, using the battery life model, a loss in battery capacity as a sum of a parametric function and a nominal loss,
wherein the parametric function depends on a cell temperature, a state-of-charge, and a depth of discharge.