A model of the effects of automatic generation control signal characteristics on energy storage system reliability
Date
2012
Authors
Campbell, Timothy M., author
Bradley, Thomas H., advisor
Zimmerle, Daniel, committee member
Young, Peter M., committee member
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Abstract
No electrochemical batteries constructed to date have the storage capacities necessary for integration into conventional energy markets; aggregation will be required to meet industry-standard metrics for reliability and availability. This aggregation of individual energy storage devices into a distributed energy storage (DES) system will be useful not only to allow standard connection to the grid, but to provide higher-quality fast-response grid services with low-cost technologies. These smaller installations will have lower capital costs than traditional energy storage facilities. Ancillary services, and more specifically frequency regulation services, are understood to be the most technically viable and economically valuable market available to DES. Accordingly, this study is based on the properties of the frequency regulation market. This study presents a simplified model of a DES resource, its frequency regulation actuation signal, and its mode of market participation. The inputs to the model are scaling parameters of the DES system and of the actuation signal. The outputs from the model are the individual and aggregated reliability of the DES system. An analytical calculation of reliability is performed and analytical results are compared to numerical simulation solutions. Results show that the reliability of the energy storage device can be characterized using a set of non-dimensional parameters. These device-level reliability results are then translated into system-level reliability through several different models of ancillary services contracting and dispatch. Previous studies of DES systems have assumed that the energy storage system has no energy storage limitations and that the actuation signal has no net or instantaneous energy content. This model includes these conditions so as to capture the interaction between the energy content of the Automatic Generation Control (AGC) signal and the device-level and system-level reliability of DES systems. These results are novel in that they can guide the independent system operator/balancing authority in constructing an AGC signal specific to the needs of DES system resources.
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Subject
automatic generation control
frequency regulation
energy storage
battery-to-grid