Photovoltaic wave power suppression control method based on improved wavelet packet transform

The hybrid energy storage system consisting of a lithium-ion battery pack and a super capacitor is currently a common method of suppressing fluctuations in the output power of microgrid photovoltaics. Using the wavelet packet analysis method to decompose the photovoltaic output power, the power components in different frequency bands can be obtained. However, the traditional wavelet packet decomposition method has a fixed number of decomposition layers and cannot follow the change of photovoltaic output power in real time. This paper proposes an improved wavelet packet decomposition method. Considering the fluctuation of solar cell output power and the current working state of the hybrid energy storage system, the fuzzy control algorithm is used to adjust the number of wavelet packet layers in real time to achieve a self-adaptation of the power fluctuations during the stabilisation process. The lithium-ion battery and the supercapacitor state of charge are considered., The use of fuzzy control to their secondary output power distribution, improve the effect of stabilisation. Experiments show that compared with the control method based on traditional wavelet packet, the control method proposed in this paper improves the control effect by 4.5%.