直流微网柔性互联开关控制策略研究

发布时间：2018-03-25 22:10

本文选题：直流微网　切入点：柔性互联开关　出处：《北京交通大学》2017年硕士论文

【摘要】：微网作为一种整合分布式电源、储能系统和负荷的有效组织形式,自提出后逐渐受到国内外学者的广泛关注和研究。但以往的研究主要集中于交流微网,随着具有直流特性的分布式电源和直流负荷的增加,直流微网的研究意义日益凸显。以往对于直流微网的研究主要集中于微网内部,如直流微网内部的多源协调控制和储能优化配置等,但对于直流微网间能量调度控制策略等的研究还不是很多。本文以此为切入点,分析了利用柔性互联开关进行直流微网互联和能量调度的控制策略,重点从以下几个方面对柔性互联开关及其与直流微网构成的直流配电系统展开研究。(1)对柔性互联开关在不同工作模式下的工作原理进行了详细理论分析,采用双载波三模式调制方式来实现柔性互联开关在降压、升降压和升压三种模式之间的平滑切换。分析了柔性互联开关的单电流环和电压电流双闭环控制方式,并通过仿真和实验进行验证,证明了相关理论分析的正确性。(2)为实现柔性互联开关进行直流微网互联和能量调度的功能,设计了柔性互联开关的一次调节下垂控制策略。柔性互联开关将检测到的两端微网母线电压大小输入到控制器中,控制器根据设定好的下垂曲线计算出潮流调度的大小和方向。下垂曲线的设置与直流微网内部储能变流器的控制相协调,通过微网间的能量调度使直流微网之间相互支撑,以维持两侧微网母线电压均处于合理范围。接着介绍了柔性互联开关的并联运行控制策略,说明了柔性互联开关在并联运行上的可行性。(3)为辅助实现对两侧直流微网储能SOC(State of Charge)的优化调节,在柔性互联开关一次调节的基础上增加了二次调节功能。二次调节是指柔性互联开关的一次调节下垂控制曲线会根据两侧微网储能SOC的状态上下平移。柔性互联开关在得到两侧微网储能SOC的大小后,由控制器根据相应的公式计算出平移量,将能量从SOC高的一侧调度到低的一侧,以维持两侧微网储能SOC于合理范围内,实现对储能单元SOC的优化调节,延长其使用寿命。(4)对三种模式下的柔性互联开关进行了小信号建模,以柔性互联开关工作于Buck模式为例,推导了柔性互联开关及两侧直流微网在柔性互联开关工作于Buck模式时的数学模型,并对其在下垂控制策略下的稳定性进行了分析,说明了各控制变量的取值变化对直流微网运行稳定性的影响。(5)在以上理论分析的基础上,在Matlab/Simulink中搭建仿真模型,并且搭建了基于dSPACE1103的半实物仿真平台,对相关理论和控制策略的正确性进行仿真和实验验证。
[Abstract]:As a kind of effective organization form of integrating distributed power supply, energy storage system and load, microgrid has been paid more and more attention by scholars at home and abroad since it was put forward. With the increasing of DC power supply and DC load, the research of DC microgrid is becoming more and more important. For example, multi-source coordinated control and optimal configuration of energy storage in DC microgrid, but there are not many researches on the control strategy of energy scheduling between DC microgrids. The control strategy of DC microgrid interconnection and energy scheduling using flexible interconnected switches is analyzed. In this paper, the flexible interconnected switch and its DC distribution system composed of DC microgrid are studied from the following aspects. The working principle of the flexible interconnected switch in different working modes is analyzed in detail. The double carrier three mode modulation mode is used to realize the smooth switching between three modes of flexible interconnected switch, i.e., the step-down mode, the lifting mode and the boost mode. The single current loop and voltage and current double closed loop control mode of the flexible interconnect switch are analyzed. Through simulation and experiment, it is proved that the correctness of the related theoretical analysis is the function of DC micro-grid interconnection and energy scheduling for flexible interconnected switches. The droop control strategy of the flexible interconnect switch is designed. The voltage of the microgrid bus is input to the controller by the flexible interconnect switch. The controller calculates the size and direction of power flow scheduling according to the set droop curve. The setting of droop curve is coordinated with the control of the internal energy storage converter of DC microgrid, which supports each other through the energy scheduling between microgrids. In order to maintain the voltage of microgrid bus in a reasonable range, the parallel operation control strategy of flexible interconnected switch is introduced. The feasibility of flexible interconnected switch in parallel operation is explained. The secondary regulation function is added on the basis of the primary regulation of the flexible interconnected switch, which means that the droop control curve of the primary regulation of the flexible interconnected switch will be shifted up and down according to the state of the energy storage SOC on both sides of the microgrid. After the switch gets the size of the energy storage SOC on both sides of the microgrid, The translation amount is calculated by the controller according to the corresponding formula, and the energy is scheduled from the high side of SOC to the low side, in order to maintain the energy storage SOC of both sides of the microgrid within a reasonable range, the optimal regulation of the energy storage unit SOC can be realized. Prolonging its service life. (4) small signal modeling of flexible interconnected switches in three modes is carried out. Taking flexible interconnected switches working in Buck mode as an example, The mathematical models of flexible interconnected switch and DC microgrid in Buck mode are derived, and its stability under droop control strategy is analyzed. This paper explains the influence of the change of control variables on the operation stability of DC microgrid. On the basis of the above theoretical analysis, the simulation model is built in Matlab/Simulink, and the hardware-in-the-loop simulation platform based on dSPACE1103 is built. The correctness of relevant theory and control strategy is verified by simulation and experiment.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM727

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