离网模式下逆变器接口的控制策略

发布时间：2018-05-04 21:51

本文选题：微网 + 逆变器并联　；参考：《浙江大学》2015年硕士论文

【摘要】：随着煤、石油等不可再生能源的消耗,能源危机成为人们不得不面对的问题,而太阳能、风能等能源的可再生性给解决这个问题提供了新思路。分布式发电迅速崛起,然而由于新能源的随机性和间歇性,分布式发电向传统电网接入成为新问题。一些科学家提出将这些分布式新能源与一些储能单位整合成一个有机的整体共同控制,因此产生了微网的概念。微网的稳定运行离不开合理的控制技术,因此对微网中微源控制的研究十分有必要。微网中微源接口包括传统的发电机型接口和逆变器型接口,由于新能源大多采用逆变器型接口并网,因此本文的主要研究对象是逆变器型微源及其并联系统的控制方式。逆变器型微源的接口控制方式包括恒功率控制、恒压恒频控制和下垂控制。下垂控制能够利用本地信息控制,通信要求较低,是本文研究的主体,同时恒压恒频控制在稳定频率和电压方面起到重要作用,本文也对其进行了仿真和研究。传统下垂控制中并未对线路阻抗进行合理分析和考虑,当线路阻抗为感性时有功和无功功率才能解耦和正确控制,而低压微网中线路阻抗为阻性,使用传统下垂控制会导致有功和无功功率耦合,此外由于线路电压降的不同,无功功率不能够按照设定的比例分配,这会使一些微源超过容量或出现严重的过流,对微源造成损害。针对低压微网中传统下垂控制无法适用的问题,本文在相关文献无功功率理论基础上,推得逆变器无功功率输出与负载端电压的线性关系,提出了一种改进的下垂控制方法。该方法将线路阻抗看做逆变器内阻的一部分,测量负载端的电压作为电压电流双闭环控制的参考信号,并添加虚拟电感调节线路阻抗的性质,使有功和无功功率解耦。最后对改进下垂控制的功率控制模块、虚拟阻抗模块和电压电流双闭环模块进行了设计和分析。在Matlab/Simulink软件环境下的仿真结果验证了该控制方法的有效性。
[Abstract]:With the consumption of non-renewable energy such as coal and petroleum, the energy crisis has become a problem that people have to face, and the renewable energy such as solar energy and wind energy provide a new way to solve this problem. Distributed generation is rising rapidly. However, due to the randomness and intermittency of new energy, the access of distributed generation to traditional power grid becomes a new problem. Some scientists put forward the idea of integrating these distributed new energy sources and some energy storage units into an organic whole control system, which resulted in the concept of microgrid. The stable operation of microgrid can not be separated from reasonable control technology, so it is necessary to study microsource control in microgrid. The microsource interface in the microgrid includes the traditional generator interface and the inverter interface. Since the inverter interface is mostly used in the new energy source, the main research object of this paper is the control mode of the inverter microsource and its parallel system. The interface control methods of inverter microsource include constant power control, constant voltage and constant frequency control and droop control. Droop control can use local information control, communication requirements are low, is the main body of this study, and constant voltage and constant frequency control plays an important role in stabilizing the frequency and voltage, this paper also simulates and studies it. In the traditional droop control, the line impedance is not reasonably analyzed and considered. When the line impedance is inductive, the active and reactive power can be decoupled and controlled correctly, but the line impedance in the low-voltage microgrid is resistive. Traditional droop control can lead to active and reactive power coupling. In addition, reactive power can not be distributed according to the set proportion because of the different voltage drop of the line. This will cause some microsources to exceed capacity or cause serious overcurrent. Damage to microsources. Aiming at the problem that traditional droop control can not be applied in low-voltage microgrid, based on the theory of reactive power, the linear relationship between reactive power output and load terminal voltage of inverter is deduced in this paper, and an improved droop control method is proposed. In this method, the line impedance is regarded as a part of the inverter's internal resistance, the voltage at the load end is measured as the reference signal of the voltage and current double closed loop control, and the property of the line impedance is adjusted by the virtual inductance to decouple the active and reactive power. Finally, the power control module, virtual impedance module and voltage and current double closed loop module are designed and analyzed. The simulation results under the Matlab/Simulink software environment verify the effectiveness of the control method.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM464

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