20-09-2012, 12:34 PM
Micro Grid Energy Storage Demonstration
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Project Overview
This project will demonstrate the use of ultracapacitor energy storage module in support of a selection of distributed energy resources that could potentially be configured as an electric microgrid. To support the demonstration, Palmdale Water District (Palmdale) in California has installed a variety of new distributed energy resources to supply facility power in an environmentally friendly way. These resources include a 950 kilowatt wind turbine, a 200 kilowatt natural gas generator, and a 250 kilowatt water turbine generator. It is expected that with these new distributed generation sources, the facility will be able to supply the majority of its electric power needs for the near future.
To supplement the electrical performance of these technologies, Northern Power Systems will develop and demonstrate a 450 kilowatt storage system called the electric energy storage system. Data collection and management for this system demonstration is being funded by the U.S. Department of Energy (DOE). The system will be installed at Palmdale’s Clearwell Pumping Station (Clearwell). The energy storage system utilizes ultracapacitors coupled with advanced power electronics and controls to maintain electric grid stability even during brief power system variations and momentary power interruptions.
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 offers a unique opportunity to demonstrate and better understand the capabilities of a zinc bromine battery based storage system and compare the economics and lifecycle costs to some of the other T&D deferral options currently available.
The benefits to the state of California, based on a successful demonstration of the ZBB technology would be the ability to reduce peak demand on the electric power system while continuing to support customer loads and allowing those customers that may normally see a blackout to continue with process operation and production. The technology has the potential to relieve transmission and distribution capacity at needed times. This is also one of the first demonstration projects where real time monitoring and data collection are being used to measure system performance and validate the system performance claims.
This project is being sponsored by CEC and DOE to better understand two key Distributed Energy Storage Technology objectives:
To evaluate the ability of the energy storage system to improve power quality for the facilities critical loads.
To demonstrate the ability of the energy storage system to isolate part of the facility without shutting down any of the critical equipment during the transition from the grid to the backup generator.
The benefits to the state of California, based on a successful demonstration of the energy storage system technology would be the ability to reduce peak demand by enabling facilities to remove load from the power system while continuing with process operation and production. This would potentially relieve transmission and distribution capacity at needed times. This is also one of the first demonstration projects where real time monitoring and data collection are being used to measure system performance and validate the system performance claims.
How the Technology is Being Applied
The Palmdale power system includes: a 450 kW energy storage system , a 250 kW hydroelectric genset, a 200 kW natural gas genset, an 800 kW diesel back-up genset, and the Clearwell pumping station loads (760 kW).
Power reliability will be provided for a portion of the Clearwell loads. Approximately 400 kW of critical loads are currently identified including pumps, controls, instrumentation and security equipment.
Critical loads will receive power quality benefits from the energy storage system when grid-connected, and also when transitioning to and from backup power.
The 950 kW wind turbine will always be grid connected but will go off line in the event of a utility outage.
Interaction between the wind turbine and the energy storage system will be monitored and avoided power quality and stability events will be quantified. The monitoring and data acquisition has been specified such that system availability, power quality, and energy parameters will be accessible via the website. Any time the storage system is operated, plots of the power into the facility and power quality delivered to the critical loads will be captured and viewable via the historical archives.
The 450 kW energy storage system components includes the development and integration of two ultracapacitor modules, a static isolation switch, system monitoring/controls, data acquisition, and human interface. The power network will combine power generation, advanced load management, and critical energy storage elements utilizing advanced controls and switching technologies.
Power sources include a 950 kW wind turbine, a planned 250 kW hydroelectric plant, an existing 250 kW natural gas generator,a nd existing 800 kW and 350 kW diesel generators. The total load at the site is approximately 1.25 MW. The energy storage system will be designed to operate in parallel with the utility as a line interactive device, continuously providing voltage support, power factor correction, harmonic improvement, and transient mitigation. This architecture will not only facilitate integration of backup devices such as fuel cells, microturbines, and wind turbines into advanced power networks.
Technology Description
The energy storage system utilizes ultracapacitors coupled with advanced power electronics and controls to maintain electric grid stability even during brief power system variations and momentary power interruptions.
About Ultracapacitors
A capacitor is an electronic device that stores an electric charge using two conductive surfaces separated by an insulator. Energy is stored within the dielectric insulator using electrostatic charges on opposing surfaces that can withstand a very large number of charge/discharge cycles without degradation. The amount of energy stored is directly related to the plate (electrode) area and to the dielectric constant of the insulator, but inversely related to the plate separation. Ultracapacitors use this same principal, however the electrodes are made of ultra-high surface area activated carbon, which allows for much greater charge storage than that of traditional capacitors. In many respects, ultracapacitors are similar to batteries, including the use of liquid electrolytes and the ability to connect cells to make higher power arrays.
As in any capacitor, the amount of capacitance is directly related to the surface area of the electrode. When fabricated into felt or woven into a fabric, activated carbon makes an excellent electrode structure having good mechanical integrity and electrical conductivity. The surface area of a carbon electrode is an amazing 1000-2000 m2/cm3. The large surface area is what gives the ultracapacitor the ability to store a large amount of energy and power in a small area. This incredibly large surface is equivalent to stuffing the surface area of a baseball field into a space the size of a baseball!