This project demonstrates a flywheel energy storage system designed to respond to a regional transmission operator signal to quickly add or subtract power from the grid in a frequency regulation support mode. Using this concept, the flywheel recycles energy (store energy when generation exceeds loads; discharge energy when load exceeds generation) instead of trying to constantly adjust generator output.
The California Energy Commission is supplying project implementation funding and the US Department of Energy ESS program is sponsoring and funding the data management, collection and analysis activities. The data management activities are directed by Sandia National Laboratories through contracts with EPRI and Distributed Utility Associates.
Why is CEC/DOE Sponsoring This Project
This project is being sponsored to determine the relative benefits of having faster responding generation resources. Additionally, understanding the response time of a flywheel storage system as compared to traditional generator response time will provide a better determination of the required sizing for flywheel and other fast response systems.
When aggregated to reach appropriate output/input levels there are many benefits that a flywheel energy storage system (FESS) can offer to the electric grid. The primary benefits are:
- Increased Available energy: Because present day generators need to be operated below their maximum capability to provide regulation, they are not available to provide their maximum power. Typically generators need to be below their maximum capacity by 2 times the amount of regulation in order to provide headroom for safe operation. If all regulation were accomplished by FESS, then there would be an additional 2-4 % generation capacity without adding new generators.
- Support Distributed Generation with Local Voltage Support: Several Projects have already shown the benefits of using flywheels for local voltage support. This includes a project on the NY City transit system, where ten 1.6 KWh flywheels provide support between train stations. As flywheel storage increases, as will be demonstrated by this project, the feasibility of larger scale application of FESS for local voltage support will be more practical.
How the Technology is Being Applied
The FESS consists of an array of flywheel energy storage modules and power conversion electronics packaged in a standard 12’ x 40’ shipping container. This mobile container would interface with the grid’s three-phase 480-volt cables via a step up transformer. This matrix is capable of storing and recycling 250 kWh’s of energy. The rated discharge rate of a matrix is 1 MW therefore each container will provide rated power for 15 minutes or lower power for an extended period.
Monitoring and data acquisition has been specified such that system availability and power/energy parameters will be accessible via the website. Any time the system is operated, the kilowatts supplied or absorbed by the storage unit and the total system efficiency will be viewable via graphical display by day, week, month, etc.
While performing the Frequency Regulation, the FESS will receive two input signals from the System Operator.
- Regulation Signal (RS): This will be the amount of regulation to be provided over the next time step. This value will be between (-)100KW and (+) 100KW. Minus refers to absorbing 100kW of power from the Grid. Plus refers to injecting 100 kW of power to the grid. The regulation signal refers to the amount of power being absorbed or injected relative to a base set point as described by signal 2. The amount of power being injected or absorbed will be as measured downstream of the FESS and upstream of the step up transformer. This regulation signal will be updated every 4 seconds.
- Set Point (SP): This will be the nominal level of power being removed from the grid during the time on regulation. It will be a percentage of the full regulation signal and will be a variable during the demonstration phase of testing. This setting will remain constant over an agreed to time period usually one to 24 hours. In addition to the set point and regulation signal the master controller will have input from the flywheel controller to know how much energy is in each flywheel. The system controller will then send a signal to the flywheel controllers, and load bank to control the power flow within and to and from the FESS based on these inputs.
The system will be installed and demonstrated at the PG&E DUIT facility in San Ramon, California. It will be run for a period of six months to demonstrate its ability to interface with the ISO signals and grid. Data will be independently collected through funding provided by the U.S. DOE and used to estimate the system performance over time. In this demonstration Beacon Power is providing seven 15 kW flywheels in a parallel configuration. The FESS will follow the regulation signal within a fraction of a percent. Unlike generation based frequency regulation, no fuel is consumed, and no emissions are generated. Analysis of presently used frequency regulation signals indicates that an energy storage module, which can store or deliver 1 MW for 15 minutes, would provide regulation services superior to services currently provided by generators. After development testing is completed the FESS will be commissioned and put on automatic control.
For more informtion you are invited to watch Beacon Power's Flash presentation on flywheels and frequency regulation.
Click here for the Technology Description.
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