含大规模风电的电力系统负荷频率控制的自抗扰设计

发布时间：2018-07-12 08:24

本文选题：线性自抗扰控制 + 线性二次型高斯最优控制　；参考：《华北电力大学(北京)》2017年硕士论文

【摘要】：现今,风能是应对全球能源危机最为主要的可再生能源之一。近年来随着风电技术和规模的不断发展,风电场在电力系统中所占比例逐步增大,但由于风电输出功率具有随机性和波动性,其大规模并网会引起电力系统频率的波动,从而降低电力系统的频率控制能力。为保证电力系统的安全性和频率稳定性,针对大规模风电机组并网后电力系统的频率稳定问题进行研究并设计能适应并抑制系统输出频率波动的负荷频率控制器是十分必要的。线性自抗扰控制器(LADRC)结构简单、不依赖精确数学模型和具有较强的适应性和鲁棒性,但仅用带宽法进行整定,控制器的控制性能会受到限制。本文在针对含大规模风电的电力系统负荷频率波动的LADRC结构和设计方面,为提高其抗干扰控制性能,考虑将过程的复杂动态加入到LADRC控制结构中,利用被控对象已知的信息,设计了改进型的LADRC控制策略,提出了实际可行的能克服风电场负荷波动的频率控制方案。方案一将风电负荷视为负荷频率控制系统的随机干扰。利用线性二次型高斯最优控制(LQG)对随机干扰抑制效果好的优点,提出LQG-LADRC两步法控制器设计方案。该方案首先根据被控对象模型设计了LQG,其次在不改变干扰抑制性能的前提下把设计好的LQG转换成LADRC,使得LADRC可以完全实现LQG的抗干扰性能。这种改进方法可以更好地估计扰动,能够更加充分地利用LQG和LADRC各自的优点,使得LADRC控制器抑制随机干扰的能力进一步得到提高。方案二将风电负荷视为负荷频率控制系统的不确定扰动。利用干扰观测器(DOB)对不确定干扰控制效果好的优点,本文提出了一种DOB-LADRC两步法控制器设计方案。该方案首先设计了一个基于DOB的两自由度控制系统,其次在不改变干扰抑制性能的前提下把设计好基于DOB的控制器转换成LADRC,使得LADRC可以完全实现DOB的抗干扰性能。这种改进方案优化了含不确定干扰的负荷频率系统控制性能,使得风电场引起的负荷频率波动最小化,达到更好的控制品质。最后,本文建立了风力机和电力系统负荷频率模型,针对电力系统中风力发电的干扰,运用以上两种方案进行仿真分析。并将所提方案与IMC-PID控制、基于带宽法整定的LADRC方案进行了对比,从干扰抑制性能和鲁棒性能两个角度验证了本文所提方案的有效性。
[Abstract]:Nowadays, wind energy is one of the most important renewable energy sources to deal with the global energy crisis. In recent years, with the development of wind power technology and scale, the proportion of wind farm in power system has gradually increased. However, due to the randomness and volatility of wind power output, large-scale grid connection will cause the frequency fluctuation of power system. Thus, the frequency control ability of power system is reduced. In order to ensure the safety and frequency stability of power system, it is necessary to study the frequency stability of power system after large-scale wind turbine is connected to grid and to design a load frequency controller which can adapt and suppress the frequency fluctuation of power system output. The linear active disturbance rejection controller (LADRC) is simple in structure, independent of accurate mathematical model, and has strong adaptability and robustness. However, the control performance of the controller is limited by only tuning by bandwidth method. In this paper, in order to improve the anti-interference control performance of LADRC structure and design of power system load frequency fluctuation with large-scale wind power, the complex dynamic process is considered to be added to the LADRC control structure, and the known information of the controlled object is used. An improved LADRC control strategy is designed, and a feasible frequency control scheme is proposed to overcome the load fluctuation of wind farm. Scheme one regards wind power load as random disturbance of load frequency control system. Based on the advantage of linear quadratic Gao Si optimal control (LQG) for suppressing random interference, a design scheme of LQG-LADRC two-step controller is proposed. Firstly, the LQG is designed according to the controlled object model, and then the designed LQG is transformed into LADRCwithout changing the interference suppression performance, so that LADRC can completely realize the anti-jamming performance of LQG. The improved method can better estimate the disturbance, make full use of the advantages of LQG and LADRC, and further improve the ability of LADRC controller to suppress random interference. The second scheme regards wind power load as uncertain disturbance of load frequency control system. This paper presents a design scheme of DOB-LADRC two-step controller based on the advantages of disturbance observer (DOB) for uncertain disturbance control. Firstly, a two-degree-of-freedom control system based on DOB is designed. Secondly, the controller based on DOB is transformed into LADRC-based controller without changing the performance of interference suppression, so that LADRC can completely realize the anti-jamming performance of DOB. The improved scheme optimizes the control performance of the load frequency system with uncertain disturbance, which minimizes the fluctuation of load frequency caused by wind farm and achieves better control quality. Finally, the load frequency model of wind turbine and power system is established, and the above two schemes are used to simulate and analyze the disturbance of wind power generation in power system. The proposed scheme is compared with the IMC-PID control and the LADRC scheme based on bandwidth tuning. The effectiveness of the proposed scheme is verified from two aspects: interference suppression performance and robust performance.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM712

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