Abstract: [Objectives] With the large-scale integration of new energy sources such as wind and solar into the power grid, their inherent randomness and volatility pose challenges to secure grid connection and consumption. Distributed compressed air energy storage (DCAES), with its advantages of high flexibility and variable speed, can effectively track power commands and mitigate the power fluctuations of renewable energy. However, using the traditional perturb and observe method for power tracking in DCAES expansion power generation systems encounters difficulties in balancing tracking speed and steady-state accuracy. To address this issue, this paper proposes a variable-step power tracking control strategy for DCAES with flexible power dispatch and excellent tracking performance. [Methods] The power variation rate and rotational speed deviation rate of the DCAES expansion power generation system are incorporated into the perturbation step size. By adaptively adjusting the step size of rotational speed variation in real-time, rapid and reliable tracking of power commands is achieved. Based on MATLAB/Simulink, the simulation model of DCAES expansion power generation system is built to verify the effectiveness of the proposed control strategy. [Results] Compared with the small step power tracking control strategy, the proposed control strategy can improve the tracking speed of the system by more than 25%. Compared with the large step power tracking control strategy, the tracking speed of the two strategies is almost the same, but the power oscillation of the proposed control strategy is below 1% of the large step amplitude. [Conclusions] The proposed control strategy improves the influence of speed step selection on power tracking, so that the system has faster dynamic tracking speed and higher steady-state accuracy.

Key words: distributed compressed air energy storage, new energy, power system, expander, permanent magnet synchronous generator, power command tracking, control strategy, variable speed step-size