光伏系统直流微网智能接口及MPPT研究

发布时间：2018-06-24 18:06

本文选题：移相全桥DC/DC控制器 + ZVS　；参考：《扬州大学》2014年硕士论文

【摘要】：太阳能作为一种无污染的绿色能源,它的开发利用越来越受到重视。直流微网中一个重要的能源来源就是光伏发电,但是太阳能电池板的输出电压一般比较低,不能直接与直流微网中高电压等级的直流母线相连,因此需要通过一个中间接口与直流母线相连,这个中间接口即为电力电子变换元件。在光伏发电系统中,DC/DC变换器常常被用来作为这一中间接口,DC/DC变换器不仅可以将光伏电池输出的低电压升高到所需求的高电压,还可以对太阳能电池实现最大功率跟踪,从而提高了电池的利用率。本文光伏智能接口主要由光伏电池,功率电路,传感器电路,调理电路,A/D转换电路,CPU控制板,手持器,Zigbee接口等组成。功率电路主要包括逆变电路,高频变压器和整流电路。传感器电路所采集的信号经过调理电路后进行A/D转换,A/D转换输出到CPU进行相应的运算与控制。手持器主要用于观测和修改参数。论文首先阐述了直流微网的现状与发展,光伏DC/DC控制器的特点和发展,分析了移相全桥ZVS PWM DC/DC全桥变换器的工作原理。在分析和研究了移相全桥DC/DC变换器的拓扑结构和控制方法基础上,搭建了PSIM移相仿真模块,对其进行了验证。针对移相全桥DC/DC变换器中因特性不一致使变压器初级产生直流分量而导致的偏磁问题,提出了不对称移相的偏磁数字抑制方法,并给出了基于TMS320F28335 DSP不对称移相的实现方法,经仿真和实验表明,取得了较好的效果。此外,系统在并入直流母线之前首先要将电压稳定到直流母线所设定的电压600V,有效的防止了在并网的瞬间将电网电压拉低。在升压时为了防止电压的过冲,加入了惯性环节,使系统使得整个系统可以安全有效的运行。最后,针对光伏电池的伏安特性具有强烈的非线性,对负载适应性较差,且太阳电池的输出功率随光照强度和温度等因素而变化的问题,采用基于正弦扰动的最大功率点跟踪(maximum power point tracking, MPPT)非线性控制方法,仿真和实验结果表明此方法控制效果很好。在完成设计和调试基于TMS320F28335DSP的CPU控制板后,制作了功率板,调理板和传感器采样板,并进行了PWM移相、A/D转换和并网等主要程序的设计和调试。针对基于直流微网中的Zigbee通讯要求,设计了相应的通讯协议和串行通讯程序。
[Abstract]:Solar energy, as a kind of green energy without pollution, has been paid more and more attention to. An important source of energy in DC microgrids is photovoltaic power generation, but the output voltage of solar panels is generally low and cannot be directly connected to the DC busbar with high voltage levels in the DC microgrid. So it is necessary to connect with DC bus through an intermediate interface, which is called power electronic conversion element. In photovoltaic systems, DC / DC converters are often used as an intermediate interface to not only increase the output voltage of photovoltaic cells to the required high voltage, but also to track the maximum power of the solar cells. Thus, the utilization rate of the battery is improved. This paper mainly consists of photovoltaic cell, power circuit, sensor circuit, conditioning circuit, A / D conversion circuit, CPU control board, handheld device, Zigbee interface and so on. Power circuit mainly includes inverter circuit, high-frequency transformer and rectifier circuit. The signal collected by the sensor circuit is processed through the conditioning circuit and then the A / D conversion is output to the CPU for corresponding operation and control. Handheld devices are mainly used to observe and modify parameters. In this paper, the current situation and development of DC microgrid, the characteristics and development of DC / DC controller are introduced, and the working principle of phase-shifted full bridge ZVS PWM DC / DC full-bridge converter is analyzed. Based on the analysis and study of the topology and control method of phase-shifted full-bridge DC / DC converter, the PSIM phase-shifting simulation module is built and verified. In order to solve the problem of bias magnetic field caused by inconsistent characteristics in phase-shifted full-bridge DC / DC converter, an asymmetric phase-shift digital bias suppression method is proposed, and the realization method of asymmetric phase shift based on TMS320F28335 DSP is presented. Simulation and experiments show that good results have been achieved. In addition, the system must first stabilize the voltage to the voltage 600V set by the DC bus before incorporating the DC bus, which effectively prevents the grid voltage from being lowered in the instant of grid connection. In order to prevent voltage overshoot, inertia link is added to make the whole system work safely and effectively. Finally, aiming at the problem that the volt-ampere characteristic of photovoltaic cell is strongly nonlinear, the adaptability to load is poor, and the output power of solar cell varies with light intensity and temperature, etc. A nonlinear control method based on sinusoidal perturbation for maximum power point tracking (maximum power point tracking,) is proposed. The simulation and experimental results show that the proposed method is effective. After the design and debugging of the CPU control board based on TMS320F28335 DSP, the power board, the conditioning board and the sensor sampling board are made, and the main programs, such as PWM phase-shifting Ar / D conversion and grid-connected, are designed and debugged. According to the communication requirement of Zigbee based on DC microgrid, the corresponding communication protocol and serial communication program are designed.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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