微网多逆变器并联电压不平衡控制方法研究

发布时间：2018-06-01 19:10

本文选题：分布式电源 + 微网　；参考：《湖南大学》2014年硕士论文

【摘要】：随着国民经济的迅猛发展，人类对电力的需求日益增大，然而能源危机和环境污染也日益加重，促进了人类对可再生能源发电技术的研究。由于可再生能源的分散性、多样性和随机性，分布式发电技术成为其必然的网络结构。近年来，分布式发电技术以其能源利用率高、污染小、可靠性高等特点受到了广泛关注，为了减少分布式电源接入对主网的不利影响，最大限度的发挥其优势，专家们提出了微网的概念。微网主要由多个分布式微源、电力电子变换装置、储能装置、保护及负荷控制等设备构成。大多数分布式微源以逆变器作为接口接入微网，，因此多逆变器型微网的运行控制及其电能质量分析与控制是微网研究的关键技术，本文是在自然科学基金重点项目《微网多逆变器并联及电能质量控制方法研究》的资助下完成的，研究内容主要涉及到：逆变器接口微源的控制策略，微网多逆变器并联电压不平衡控制方法，以及两台三相逆变器并联系统实验平台研制。（1）从微网多逆变器并联运行入手，对基于功率下垂控制的多逆变器并联控制策略进行分析。以含两个分布式发电单元的微网逆变器并联系统为例，推导了并联逆变器等效输出阻抗呈感性和阻性情况下的下垂特性表达式，以及基于电感电流前馈的电压电流双环控制的逆变器输出阻抗表达式；分析了引入虚拟阻抗的改进型功率下垂控制方法。（2）针对负载接入不对称，从而导致微电网电压出现不平衡，影响微电网稳定性及用电设备正常工作的情况，提出了一种αβ坐标系下的微电网多逆变器并联电压不平衡补偿方法。该方法包括不平衡补偿环、下垂控制环、虚拟阻抗环及电压电流环四个部分。在引入虚拟阻抗的改进型功率下垂控制基础上，通过检测三相基波正负序电压和电流，并引入一个负序无功电导Q--G不平衡下垂控制环，合成并修正指令电流参考值，以实现微电网电压的不平衡补偿。电压电流控制环采用比例谐振PR控制以实现电压电流的无静差控制。通过Matlab/Simulink仿真验证了所提的控制方法的正确性和有效性。（3）介绍了两台三相逆变器并联系统实验平台软硬件的设计与实现，通过对所开发的样机进行测试，从实验结果可以看出，所提出的控制方法不会对功率均分效果造成影响，并且可以平衡分布式电源的输出电压，能有效的进行功率控制和电压不平衡补偿，动态性能良好，验证了该方法的正确性和有效性。
[Abstract]:With the rapid development of the national economy, the human demand for electricity is increasing. However, the energy crisis and environmental pollution are becoming more and more serious, which promotes the research of renewable energy generation technology. Because of the dispersion, diversity and randomness of renewable energy, distributed power generation technology becomes the inevitable network structure. In recent years, distributed power generation technology has attracted wide attention because of its high energy efficiency, low pollution, high reliability and so on. In order to reduce the adverse impact of distributed power access on the main network, it can maximize its advantages. Experts put forward the concept of microgrid. The microgrid consists of a number of distributed microsources, power electronic conversion devices, energy storage devices, protection and load control equipment. Most distributed microsources use the inverter as the interface to access the microgrid, so the operation control and power quality analysis and control of the multi-inverter microgrid are the key technologies of the microgrid research. This paper is completed with the support of Natural Science Foundation's key project, "study on parallel connection of microgrid multi-inverter and study of power quality control method". The research content mainly involves: control strategy of inverter interface micro-source, The parallel voltage imbalance control method of microgrid multi-inverter and the experimental platform of two three-phase inverter parallel systems are developed. 1) starting from the parallel operation of microgrid multi-inverter, the parallel control strategy of multi-inverter based on power droop control is analyzed. Taking the parallel system of microgrid inverter with two distributed generation units as an example, the droop characteristic expression of parallel inverter with equivalent output impedance with inductance and resistance is derived. The output impedance expression of voltage and current double loop control based on inductance current feedforward is presented, and the improved power droop control method with virtual impedance is analyzed. In view of the asymmetry of load access, which leads to the imbalance of microgrid voltage, which affects the stability of microgrid and the normal operation of power equipment, this paper proposes a method for compensating the voltage imbalance of microgrid multi-inverter in 伪尾 coordinate system. The method includes four parts: unbalanced compensation loop, droop control loop, virtual impedance loop and voltage current loop. Based on the improved power droop control with virtual impedance, the reference value of instruction current is synthesized and corrected by detecting the positive and negative sequence voltage and current of three-phase fundamental wave, and introducing a negative sequence reactive conductance Q G unbalanced droop control loop. In order to realize the unbalanced compensation of microgrid voltage. The voltage and current control loop adopts proportional resonance PR control to realize the voltage and current control without static difference. The correctness and effectiveness of the proposed control method are verified by Matlab/Simulink simulation. This paper introduces the design and implementation of the hardware and software of the experiment platform of two three-phase inverters parallel system. Through the test of the developed prototype, it can be seen from the experimental results that the proposed control method will not affect the effect of power equalization. It can balance the output voltage of the distributed power supply, and can effectively control the power and compensate the voltage imbalance. The dynamic performance is good, and the correctness and effectiveness of the method are verified.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

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