Frequency Ensemble Analysis for ADN‐MG Systems With Heterogeneous DGs

ABSTRACT

The intermittent nature and stochastic variability inherent in renewable energy generation present significant challenges to frequency regulation in active distribution network and microgrid (ADN‐MG) systems. The frequency regulation capability of an ADN‐MG system can be enhanced by exploring the potential of complementary intermittent power outputs of heterogeneous distributed generators (DGs). Accordingly, an ensemble equivalent model is established to analyse the frequency domain of the ADN‐MG system. The frequency response characteristics are systematically investigated through three operational scenarios, and the parameter related stability condition is established. Compared with conventional frequency regulation results, the ADN‐MG system can be controlled with less state of charge for the considered energy storage units. Furthermore, the frequency domain of the ADN‐MG system is estimated from the perspective of parametric analysis, which can be implemented by equivalent transfer function‐based parameter tuning in actual engineering applications. Then a theoretical guideline is provided for parameter selection, ensuring the frequency deviation of the ADN‐MG system remains within an acceptable range. Finally, several indexes of evaluative indicators‐frequency nadir, rate of change of frequency and regulation time are introduced for quantitative analysis to further demonstrate the superiority of the proposed results. The effectiveness of frequency ensemble analysis results are validated by three examples of ADN‐MG systems with heterogeneous DGs.