Experimental data on variable pulse width modulation control strategy for compressed air energy storage (CAES)

The goal of the experiment was to analyze air expansion control strategies in a compressed air energy storage (CAES) system using pulse width modulation (PWM) and an adaptive piston cut-off point (xFC). The tests were carried out on a custom-built test stand with a multi-piston electro-pneumatic actuator in the expansion section of the CAES installation. The system was equipped with sensors to monitor pressure, temperature, airflow, piston position, and electrical parameters. Five experimental scenarios were conducted. Three of them used a variable PWM strategy to modulate the air volume delivered to the piston chambers, depending on the tank pressure. The control function was defined as xFC = s * (a * p^b), where xFC is the piston cut-off position, s is the piston stroke, p is the tank pressure, and a, b are constants. In these scenarios, the air intake was adaptively adjusted to improve the efficiency of the expansion process. The remaining two scenarios used a fixed compression factor (CFR) and constant pressure conditions. Data were recorded at a frequency of 100 Hz using a PLC in data sampling mode. The expander operated at a constant speed (32 rpm), and the electrical load was regulated using a PID controller integrated into the PLC. The PID output was used to control an Array 3760A electronic load. The experiment enabled evaluation of how different control strategies affect the performance and energy efficiency of the expansion phase in a CAES system.