Research On The Transient Power Suppression Method Based On Wavelet Algorithm

In order to reduce environmental pollution and energy depletion problems caused by the over-use of fossil fuels, as a kind of clean secondary energy, electricity has been widely used and plays an important role in the isolated electrical power system, like the powertrain system of the electric cars or that of the more electric aircraft or ships. In these occasions, energy-storage elements and bi-directional dc/dc converters set up a common energy structure form, which is called the hybrid energy storage system. To better allocate the instant power demand between different units, efficient energy management should be adopted here. For the applications mentioned above all feature the short and pulsed load power, energy management used here must pay more attention to the real time issue. In this article, the capacity configuration method and the real time coordination control strategy are researched.The main contents are as follows: 1.The principles of the offline wavelet transforms and the online wavelet transforms are introduced and influence of the key parameters which may cause different transform results is analyzed, e.g. the wavelet base function, the decomposition level, the boundary treatments and the window width. The delay problem of the wavelet transform is analyzed and some solutions are come along with. 2.Capacity configuration of HESS, which aims at the lightest weight is researched, adopting the wavelet transform. A typical case is given to compare the configuration results under different parameter selections. 3.Real time coordination of the HESS is researched, adopting the online wavelet transform. To better integrate the upper control of the power decomposition with the bottom control of the power allocation, two coordination control strategies are put forward, one based on the load power and the other based on the bus voltage. To protect the energy storage units from damage, the super-capacitor's SOC feedback control is added to the basic control. 4.Matlab/Simulink simulation model is set up to demonstrate the feasibility of the real time strategies. Parameter designs of the subsystems are given, including the front-end bi-directional dc/dc converters of the energy storage units, which are used as charger or discharger; the pulsed power load, which is made up of high frequency switches and power resistors; the regenerative power load, which is simply fulfilled with battery and boost converter. The above mentioned two strategies are applied to the system simulation model respectively and comparisons are made between the two. Finally, the super-capacitor's SOC feedback control is added to the system simulation and proved to be efficient.