Research On The Configuration Of The Hybrid Energy Storage System In The Grid-connected Distributed PV System

Output of the grid-connected distributed photovoltaic generation system ap-pears to be intermittent and random due to the influence of solar radiation in-tensity, temperature, shielding of the cloud and other factors. In this disserta-tion, a grid-connected distributed photovoltaic generation system which hasthe output power of3.5kW was chosen to configure the hybrid energy storagesystem (HESS) so that the exchanged power with the grid would besmoothed.Background and related researches was introduced in the first place. Topologyof the grid-connected distributed photovoltaic generation system was ana-lyzed, mathematical models of photovoltaic cells and HESS introduced, anddata preprocessed.Hierarchical HESS control strategy which controls the HESS progressivelyfrom the system level to the device level was proposed. For the system-levelcontrol strategies, the first-order filtering method was assessed to be the mostsuitable. Adding a series of constraints, a modified version was proposed which was then applied in the following calculation. The configuration of thebattery and the ultra capacitor was executed one after another based on dif-ferent sets of data. The method was then validated to be effective and feasibleby the example.Following are the innovations of this dissertation:1) Having proposed amodified HESS control strategy on the basis of the first-order filtering methodunder the constraints of charging and discharging power and the capacity.2)Having introduced the probability of the execution failure as the evaluationcriteria to indicate the adaptability degree of the configuration regarding to aparticular control strategy.3)Having proposed a two-step HESS configurationmethod which was to execute the configuration of the battery and the ultracapacitor one after another and consequently reducing the complexity of thecalculation.