基于负荷预测的风柴储混合发电系统频率控制方法研究

发布时间：2018-05-04 05:35

本文选题：风柴储混合发电系统 + 频率控制　；参考：《电子科技大学》2014年硕士论文

【摘要】：随着全球常规能源的枯竭,世界各国纷纷开始关注分布式发电。由于分布式电源的不可控性和随机性,其渗透率的提高增加了对电力系统稳定性的负面影响。为充分利用可再生能源和对各种分布式发电单元进行有效管理,提出了微网结构。微网有并网和孤岛运行两种模式,当微电网运行于并网模式时,其频率由大电网提供支撑;当微电网运行于孤岛模式时,与大电网连接断开,微网只能依靠自身来维持频率的稳定。由于负荷的不可预测性、风能的随机性和间歇性使得微网运行时的频率控制具有一定难度,频率控制成为了微网孤岛运行时的关键问题。针对微网孤岛运行时频率难控制的问题,本文提出了一种基于负荷和风力发电预测的风柴储微网频率控制方法,主要研究内容如下:1、研究并分析了风柴储微网的结构和主要组件的运行特性,并给出了基于负荷和风力发电预测的风柴储微网频率控制方法的原理和控制结构图,该控制结构由基于负荷预测的风柴分配模块和储能电池实时控制模块组成。2、为了减小风电和负荷波动对于系统频率的影响和充分利用负荷和风力发电的预测信息,本文设计了风柴功率分配模块,根据风力发电机和柴油机下一时刻的预测值与此时的实际值之间的差值设计了模糊控制器,修正了风机和柴油机的分配功率值,减小可能出现的有功功率供需之间的差额,从而减小了微电网可能出现的频率波动。利用仿真软件MATLAB搭建模型,与不利用负荷和风力发电的预测信息的频率控制策略对比,仿真结果表明本文提出的控制方法不仅能够很好地控制系统的频率波动,还能够平滑柴油机的输出,避免了其频繁动作,减小了对柴油机的损耗,还能够减小储能电池的充放电功率,避免储能电池过充过放。3、由于预测数据与实际数据之间有误差,需要利用储能电池来实时地控制微电网的频率。但是储能电池传统的下垂控制存在下垂系数调节困难,有静差,抗干扰能力差的缺点,有必要对其进行改进。本文设计了基于扩张状态观测器的实时频率补偿控制器,将负荷与风电的波动当作系统的干扰,将储能电池和微网的传递函数转换为状态空间表达式,作为被控对象,调整控制器的参数,使得微网的频率稳定在额定值附近,利用仿真软件MATLAB搭建模型,与传统的下垂控制策略进行对比,仿真结果表明基于自抗扰控制器的储能电池实时频率控制策略的频率稳定性更强,抗干扰能力也增强。
[Abstract]:With the depletion of global conventional energy, the world began to pay attention to distributed power generation. Due to the uncontrollability and randomness of distributed power generation, the increase of permeability increases the negative impact on power system stability. In order to make full use of renewable energy and manage all kinds of distributed power generation units, a microgrid structure is proposed. Microgrid has two modes: grid-connected mode and islanding operation mode. When microgrid is running in grid-connected mode, its frequency is supported by large grid, and when micro-grid is running in islanding mode, it is disconnected from large grid. Microgrids can only rely on themselves to maintain frequency stability. Because of the unpredictability of load and the randomness and intermittency of wind energy, it is difficult to control the frequency of microgrid operation, and frequency control has become a key problem in the operation of microgrid island. In order to solve the problem that the frequency of microgrid island is difficult to control, a new frequency control method based on load and wind power generation prediction is proposed in this paper. The main contents of this paper are as follows: 1. The structure and operation characteristics of the main components of the micro-grid are studied and analyzed, and the principle and control structure of the frequency control method based on load and wind power generation prediction are given. The control structure consists of a load forecasting module based on wind and firewood distribution and a real time control module of energy storage battery. In order to reduce the influence of wind power and load fluctuation on system frequency and make full use of the forecasting information of load and wind power generation. Based on the difference between the predicted value and the actual value of the next moment of the wind turbine and diesel engine, the fuzzy controller is designed, and the distribution power value of the fan and diesel engine is corrected. The difference between supply and demand of active power is reduced, which reduces the frequency fluctuation of microgrid. The simulation software MATLAB is used to build a model, which is compared with the frequency control strategy without the predictive information of load and wind power generation. The simulation results show that the proposed control method can not only control the frequency fluctuation of the system very well. It can also smooth the output of the diesel engine, avoid its frequent action, reduce the loss of the diesel engine, reduce the charge and discharge power of the energy storage battery, and avoid the overcharge and overdischarge of the energy storage battery. Because of the error between the predicted data and the actual data, Energy storage batteries need to be used to control the frequency of the microgrid in real time. But the traditional droop control of energy storage battery is difficult to adjust the sag coefficient, has the shortcomings of static error and poor anti-interference ability, so it is necessary to improve it. In this paper, a real-time frequency compensation controller based on extended state observer is designed. The fluctuation of load and wind power is regarded as the disturbance of the system, and the transfer function of energy storage cell and microgrid is converted into the expression of state space, which is regarded as the controlled object. The parameters of the controller are adjusted to make the frequency of the microgrid stable near the rated value. The simulation software MATLAB is used to build the model, which is compared with the traditional droop control strategy. The simulation results show that the real-time frequency control strategy of energy storage battery based on ADRC has stronger frequency stability and stronger anti-jamming ability.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM614

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