1 Abstract-- This paper discusses the modeling and the dynamic performance of a compressed air energy storage (CAES) plant that converts excess energy available in the power system into stored pneumatic energy by means of a compressor. The charge and discharge modes of the device are performed within maximum power conditions, so that an intermittent time- modulated operation with adjustable speed of the rotor pneumatic motor is required. Under this scenario, the power electronic technology and its control scheme play an important role in the effective integration of the CAES system into the electrical power grid. The dynamics of the electronic power conditioning system (PCS) directly influences the validity of the CAES in the dynamic control of the power system since it allows controlling the power exchange between them. The analysis of the proposed systems is performed by computer simulation using SimPowerSystems of MATLAB/Simulink. Index Terms-- Energy Storage, Compressed Air Energy Storage (CAES), Power Conditioning System, Detailed Modeling, Control Design. I. INTRODUCTION n the last years, a rising interest on non-contaminant energy sources has emerged from both, the industrial and academic communities. Two major renewable energy sources (RES), i.e. wind and solar, are today economically feasible alternatives to conventional electric power generation. Considering the integration into the power grid of these RES technologies, that are intermittent energy sources, the installation of energy storage systems is critically required in many cases [1]. To date, electrochemical batteries are the leading storage solution in order to support renewable energy sources, but are still far from meeting the requirements of medium and long term due to its limited life cycle and the difficulties to be recycled. Recently various advanced storage technologies have been developed commercially, such as flywheels, supercapacitors, superconducting magnetic energy storage This work was supported in part by ANPCyT (Argentina) under Grant FONCYT PICT 2006 – Type I-A, Cod. No 1790. M. Martinez is whith the ANPCyT (Argentina), M. G. Molina and P. E. Mercado are with the CONICET and the Instituto de Energía Eléctrica – Universidad Nacional de San Juan, Av. Lib. General San Martín 1109 Oeste, J5400ARL, San Juan – Argentina (e-mails: mmartinez@iee.unsj.edu.ar, mgmolina@iee.unsj.edu.ar, pmercado@iee.unsj.edu.ar). (SMES), storage based on hydrogen with fuel cells, and compressed air energy storage (CAES), among others. In these sense, CAES technology has long been proposed as a significant alternative, in the middle and high power range, mainly due to their high cycle life with reduced production of waste materials they generate on the environment [2]. The development of an effective option to conventional batteries is the motivation of this research, which deals with the design and analysis of the dynamic performance of a compressed air energy storage plant, in which the stored energy is obtained by the increasing of pressure mass air. The work aims at optimizing the physical processes of the expansion of air in a pneumatic motor, in order to extract as much power as possible, which is achieved with the help of modern power electronics, control systems and storage technologies. The maximum power conditions imposed by the conversion operating state carry out an intermittent operation mode from the electronic power conditioning system (PCS) to the thermodynamic process in order to obtain an optimal control of the power supply [2]. This paper describes the design and implementation of a CAES plant and its controller for applications in the distribution network level. The CAES system consists of a pneumatic machine, a permanent magnet synchronous generator (PMSG), and a high performance PCS for connecting to the electric distribution grid. The PCS design is composed of a back-to-back ac/dc/ac power converter that enables to control simultaneously and independently the active and reactive power flows exchange with the electric grid. A maximum power point tracking (MPPT) algorithm has been implemented for the real time optimization of energy conversion within the changing conditions of the air supply. To meet the dynamics of the electric output power, a pulse width modulated (PWM) on-off operation mode is applied to the pneumatic machine. Moreover, based on the state-space averaging method a three-level control scheme is designed, comprising a full decoupled current control strategy in the synchronous-rotating d-q reference frame. The dynamic performances of the proposed systems are fully validated by digital simulation carried out by using SimPowerSystems (SPS) of MATLAB/Simulink. Dynamic Performance of Compressed Air Energy Storage (CAES) Plant for Applications in Power Systems M. Martínez, Student Member, IEEE, M. G. Molina, Member, IEEE and P. E. Mercado, Senior Member, IEEE I