光伏系统电压波动检测方法研究

发布时间：2018-05-20 23:06

本文选题：光伏 + 电压波动　；参考：《华北电力大学》2014年硕士论文

【摘要】：光伏发电一方面很好地利用了清洁能源，缓解能源危机；另一方面光伏电站发出的电能可以就地消纳，减少远距离输电造成的额外损耗；光伏电站可以与主电网互为备用，在一定程度上提高了系统的供电可靠性，是未来能源发展的方向之一，具有良好的发展前景。光伏电源输出功率受光照强度的影响较大，使得逆变器的利用率较低，且频繁的投切也会使电网的稳定性下降，电压扰动是限制光伏发电发展的瓶颈。本文在建立了光伏电池模型，分析了光伏电源输出特性，提出了指数变步长扰动观察法的光伏系统MPPT控制方法。分析了电压有效值检测法、基波分量检测法、峰值电压检测法、小波分析检测法、希尔伯特黄变换检测法以及基于数学形态学与后差分算法的检测法的优缺点和应用场合，并针对希尔伯特黄变换检测法的端点效应，提出采用镜像法进行数据延拓，有效抑制了端点效应，提高了希尔伯特黄变换检测法的实用性；针对数学形态学与后差分算法中传统形态方法采用固定结构元素的缺陷，导致其不能很好地处理各种噪声的情况，提出了利用广义形态开-闭和形态闭-开运算，结合自适应方法提出一种形态开、闭运算自适应加权组合滤波器，通过形态运算的加权组合来设计更有效的算法，以获得更好的效果。通过算例仿真，对改进的方法的有效性进行了检验。分别对电压暂降、电压暂升、电压瞬变以及电压中断做了仿真分析。仿真结果表明改进的希尔伯特黄变换检测法可以有效检测电压暂降、电压暂升以及电压中断3种电压波动类型，而且能在一定程度上定量分析出电压波动幅值情况，，但是改进的方法无法有效识别电压中断，镜像数据延拓方法可以有效抑制希尔伯特黄变换检测过程中产生的端点效应；改进的基于形态学与后差分算法的检测法可以有效检测出电压暂降、电压暂升、电压中断以及电压瞬变4种电压波动情况，而且能够精确求得电压暂降和电压暂升的幅值，发生电压瞬变时，只能通过检测瞬时频率来求得电压瞬变发生时刻，发生电压中断时只能通过检测幅值随时间变化曲线来求得电压中断起始时刻。
[Abstract]:On the one hand, photovoltaic power plants make good use of clean energy to alleviate the energy crisis; on the other hand, the electricity generated by photovoltaic power plants can be absorbed locally, reducing the additional losses caused by long-distance transmission, and photovoltaic power plants can be used as a reserve with the main grid. To a certain extent, it improves the reliability of the power supply system, and is one of the directions of energy development in the future, and has a good development prospect. The output power of photovoltaic power is greatly affected by the intensity of light, which makes the utilization rate of inverter low, and the stability of power grid will be reduced by frequent switching. Voltage disturbance is the bottleneck to limit the development of photovoltaic power generation. In this paper, the photovoltaic cell model is established, the output characteristics of photovoltaic power supply are analyzed, and the MPPT control method of photovoltaic system based on exponential variable step perturbation observation method is proposed. The advantages and disadvantages of voltage RMS detection method, fundamental component detection method, peak voltage detection method, wavelet analysis detection method, Hilbert yellow transform detection method and detection method based on mathematical morphology and post differential algorithm are analyzed. Aiming at the endpoint effect of Hilbert-Huang transform detection method, the image method is proposed to carry out data continuation, which effectively restrains the endpoint effect and improves the practicability of Hilbert-Huang transform detection method. In view of the defects of the traditional morphological method in mathematical morphology and post-difference algorithm, which can not deal with all kinds of noises well, the generalized morphological open-close and morphological closed-open operations are proposed. Combined with adaptive method, an adaptive weighted combinatorial filter with morphological open and closed operations is proposed. A more effective algorithm is designed by weighted combination of morphological operations to obtain better results. The effectiveness of the improved method is verified by an example. The voltage sag, voltage surge, voltage transient and voltage interruption are simulated and analyzed respectively. The simulation results show that the improved Hilbert-Huang transform detection method can effectively detect three types of voltage fluctuation, such as voltage sag, voltage surge and voltage interruption, and can quantitatively analyze the voltage fluctuation amplitude to a certain extent. However, the improved method can not effectively identify the voltage interruption, and the image data continuation method can effectively suppress the endpoint effect in the detection process of Hilbert-Huang transform. The improved detection method based on morphology and post-differential algorithm can effectively detect four kinds of voltage fluctuations such as voltage sag, voltage surge, voltage interruption and voltage transient, and can accurately obtain the amplitude of voltage sag and voltage surge. When voltage transients occur, the transient time of voltage can only be obtained by detecting the instantaneous frequency, and the starting time of voltage interruption can only be obtained by detecting the curve of amplitude with time when the voltage interrupt occurs.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM615

【参考文献】