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Research On The Hierarchy Control Strategy Of Battery Energy Storage System

Posted on:2015-04-24Degree:DoctorType:Dissertation
Country:ChinaCandidate:K LiFull Text:PDF
GTID:1222330473456036Subject:Detection Technology and Automation
Abstract/Summary:PDF Full Text Request
Output power of renewable power generation systems has characteristics of fluctuation and intermittence that bring significant adverse effects to safe operation of power grid. This limits large-scale access capabilities of the renewable power generation systems to the power grid. Therefore, it is quite challenging to increase proportion of the renewable power generation systems in the condition of guaranteeing safe operation of the power grid.A battery energy storage system is an effective means to increase access capabilities of the renewable power generation systems to the power grid. It has positive significance to alleviate large energy demand. However, some key challenges arise in a practical use of battery energy storage systems, for example, allocation and control problems of active and reactive power, a power output limitation resulting from charge state change of the battery energy storage system, a shock effect when switching operation condition of energy storage units, and a circulating current problem in parallel converters.Corresponding to the above problems, research has to be carried out from various perspectives of the battery energy storage system, that is, energy storage stations, energy storage units, and energy storage converters. In this thesis, starting from a system perspective, it designs a complete and integrated control system for the battery energy storage system. The control system includes four control level strategies with respect to the power grid, the energy, the power, and the current. The details contributions of the thesis are listed below.Firstly, a power control strategy based on state classification was proposed to respond the power grid scheduling system and to reduce control errors. The proposed strategy uses the relationship between the state and active power of the energy storage unit, and it consists of two allocation algorithms of the energy storage station for the active power control and the reactive power control, respectively. The first one was applied to active power control of an energy storage station. The experimental results show that the proposed strategy can be effective in balancing the energy storage of the battery energy storage system to ensure power scheduling capabilities of individual energy storage units, and thus it can reduce errors of the active power control. The second one was applied to reactive power control of an energy storage station. The experimental results show that the proposed strategy can be effective in utilizing reactive output capacity of the battery energy storage system, and thus it can simplify configuration of exclusive reactive power compensators in a power plant.Secondly, an energy control strategy based on charge state feedback was proposed to maintain charge and discharge capacity of battery energy storage systems and to extend their remaining useful lives. The proposed strategy realizes energy regulation according to charge state and low-frequency superimposed charge and discharge power of battery energy storage systems. Therefore, it can maintain charge and discharge capacity of battery energy storage systems and can extend their remaining useful lives.Thirdly, a flexible power control strategy for energy storage converters was proposed to address voltage and current shock effects when switching operation condition of energy storage converters. The proposed strategy considers operation condition switch of energy storage converters as dynamic slicing threshold change of direct current controller, alternating current controller, and reactive power controller. Experimental results show that the proposed strategy can realize flexible switching of operation conditions to improve the shock effect in the power control of an energy storage converter.Fourthly, a strategy based on dual-carrier-modulation and proportional resonant control was proposed to suppress the zero-sequence circulating current in parallel converters. The proposed strategy realizes the zero-sequence circulating current suppression in a combination way that uses dual-carrier modulation to suppress zero-sequence circulating current of high frequencies and uses proportional resonant control to suppress zero-sequence circulating current of low frequencies.Based on the above research, the proposed strategies were applied to an experimental prototype of renewable power generation. Experiences were carried out at four control levels. Experience results demonstrate that(1) the proposed strategies have advantages of low zero-sequence circulating current and smooth switch of operation conditions and in the condition of meeting basic requirements of the power grid; and(2) through the battery energy management system, the proposed strategies can effectively regulate battery energy, reduce the equivalent cycle life of batteries, and thus can extend the battery life.
Keywords/Search Tags:battery energy storage system, hierarchy control strategy, power control, energy management, flexible control, zero-sequence circulating current
PDF Full Text Request
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