Power grid photo-voltaic integration using distributed energy storage and management
Distributed energy storage within the distribution network of an electric power network at least partially supplied by time varying and unpredictable generation sources provides smoothing of energy flow within the distribution network. The distributed energy storage may include a plurality of distributed energy storage units operating under the control of a single controller or regional controllers. The distributed energy storage units may operate as groups of units or as separate units.
1. A method of integrating a plurality of renewable energy sources, the renewable energy source characterized by varying or unpredictable output with time, the method comprising:
providing a plurality of distributed energy storage units and coupling each of the distributed energy storage units to one or more of the renewable energy sources;
providing a self-contained controller and communicatively coupling the controller to each of the plurality of distributed energy storage units and to each of the renewable energy sources;
directing from the controller one or more of the distributed energy storage units to one of store energy from a coupled renewable energy source and dispatch energy from its storage to a distribution feeder;
smoothing output fluctuations of one or more of the plurality of renewable energy sources by: selectively providing reactive power, storing energy into, or dispatching energy from the distributed energy storage units under direction of the controller, and
dynamically adjusting with the controller a target state of charge of the distributed energy storage units directed to smoothing the output fluctuations.
2. The method of claim 1 , wherein coupling each of the distributed energy storage units to one or more of the renewable energy sources comprising coupling the distributed energy storage units via a distribution substation.
3. The method of claim 2 , wherein coupling the controller to each of the renewable energy sources comprises coupling the controller to power flow metering disposed within the distribution substation.
4. The method of claim 1 , wherein smoothing comprises preferentially utilizing reactive power to control voltage.
5. The method of claim 1 , comprising managing energy and capacity of a distribution feeder via a first subset of the distributed energy storage units and smoothing output fluctuations of one or more of the plurality of renewable energy sources by selectively providing reactive power, storing energy into or dispatching energy from a second subset of the distributed energy storage units.
6. The method of claim 1 , wherein smoothing comprises dynamically adjusting a state of charge of a subset of the plurality of distributed energy storage units.
7. The method of claim 1 , comprising receiving at the controller at least one of weather forecast data and solar intensity data.
8. The method of claim 7 , comprising selectively enabling or disabling energy storage to or discharge from the distributed energy storage units based upon at least one of the weather forecast data and solar intensity data.
9. The method of claim 8 , wherein selectively enabling or disabling energy storage to or discharge from the distributed energy storage units based upon at least one of the weather forecast data and solar intensity data is in accordance with one or more ramp functions.
10. The method of claim 8 , wherein selectively enabling or disabling energy storage to or discharge from the distributed energy storage units based upon at least one of the weather forecast data and solar intensity data comprises at least one of schedule photo-voltaic (PV) energy time shifting; irradiance driven PV energy time shifting based upon real-time, hour and day forecast data; and irradiance driven PV energy time shifting with local measurement.
11. The method of claim 1 , comprising associating the plurality of distributed energy storage units into groups, and wherein directing from the controller one or more of the distributed energy storage units to one of store energy from a coupled renewable energy source and dispatch energy from its storage to a distribution feeder comprises directing from the controller one or more of the groups of distributed energy storage units to one of store energy from a coupled renewable energy source and dispatch energy from its storage to a distribution feeder.
12. The method of claim 1 , wherein smoothing output fluctuations of one or more of the plurality of renewable energy sources by selectively providing reactive power, storing energy into or dispatching energy from the distributed energy storage units under direction of the controller comprises selectively providing reactive power, storing energy into or dispatching energy from the distributed energy storage units in accordance with a state-of-charge of the distributed energy storage unit.
13. The method of claim 1 , smoothing output fluctuations of one or more of the plurality of renewable energy sources by selectively providing reactive power, storing energy into or dispatching energy from the distributed energy storage units under direction of the controller comprises selectively providing reactive power, storing energy into or dispatching energy from the distributed energy storage units in accordance with a trapezoidal charge/discharge energy dispatch profile.