【作者】 张立国；

【导师】 窦春霞； 张立晨；

【作者基本信息】 燕山大学 ， 控制工程（专业学位）， 2021， 硕士

【摘要】 随着不可再生能源消耗量的逐年增加,以及环境污染问题的日益加重,各个国家开始将目光转向低碳化的能源。由此,基于分布式能源的微电网应运而生,但微电网系统的控制策略及在不同工作模式间的切换稳定性仍存在很多待解决的问题。因此,本文针对相关问题进行研究,以改善微电网系统控制策略的有效性,提高运行稳定性。首先,对微电网的控制结构、运行模式、控制策略与常用分布式电源的数学模型进行了分析介绍,为后文微电网模型的建立及协调控制策略的制定提供了理论基础。其次,针对储能系统中的单储能控制策略在功率波动平抑及储能寿命管理上存在的问题,提出了双储能协调切换控制策略。两组储能针对不同条件分离或协同工作,削峰与填谷的工作任务分别由两组储能担任,不仅能够提高对分布式电源功率波动的平抑性能,还能有效延长储能寿命。并对储能系统建立了基于模型预测算法的功率波动平抑模型,以验证双储能策略的波动平抑效果。最后在双储能策略下,对储能不同放电下限进行仿真,通过对寿命损耗数据进行拟合,得出最低寿命损耗下的放电下限。然后,针对微电网各单元的协同切换问题,提出了基于强化学习的微电网多模态切换控制策略,以优化各单元的协调控制策略,实现微电网各单元的协调工作。首先,基于微电网各个单元的行为建立能够描述其所有行为与状态的行为模型与状态模型。其中在电压分层切换控制单元中,为消除母线电压在层间波动可能导致频繁触发控制命令的问题,提出了改进的电压分层切换控制策略。并针对负荷管理单元中存在的重要负荷与非重要负荷提出分区管理机制,以保证重要负荷的稳定运行。最后通过电压安全指标对系统进行安全评估并基于此设计了奖惩策略。更多还原

【Abstract】 With the increasing consumption of non-renewable energy and the aggravation of environmental pollution,countries begin to focus on low-carbon energy.Therefore,microgrid based on distributed energy resources emerges as the times require,but there are still many problems to be solved in the control strategy and switching stability between different working modes of microgrid system.Therefore,this paper studies the related problems in order to improve the effectiveness of the control strategy of microgrid system and improve the operation stability.Firstly,the control structures,operation modes,control strategies of microgrid and the mathematical models of common distributed generations are analyzed and introduced,which provides a theoretical basis for the establishment of microgrid model and the formulation of coordinated control strategy.Secondly,the single energy storage control strategy used in energy storage system has problems in the power fluctuation stabilization and the management of energy storage life.Therefore,the control strategy of coordinated switching of dual energy storage is proposed.The two groups of energy storage work separately or cooperatively according to different conditions,and the tasks of "peak clipping" and "valley filling" are undertaken by the two groups of energy storage respectively,which can not only improve the performance of suppressing the power fluctuation of distributed generation,but also effectively extend the life of energy storage.A power fluctuation suppression model based on the model prediction algorithm is established for the energy storage system to verify the fluctuation suppression effect of the dual energy storage strategy.Finally,under the dual energy storage strategy,different discharge lower limits of energy storage are simulated.Through fitting the life loss data,the discharge lower limit under the lowest life loss is obtained.Then,aiming at the problem of coordinated switching of each unit of the microgrid,a microgrid multi-modal switching control strategy based on reinforcement learning is proposed to optimize the coordinated control strategy of each unit and realize the coordinated work of each unit of the microgrid.Firstly,based on the behaviors of each unit of microgrid,the behavior models and state models which can describe all its behaviors and states are established.In the voltage hierarchical switching control unit,an improved voltage hierarchical switching control strategy is proposed to eliminate the problem that bus voltage fluctuation between layers may cause frequent triggering of control commands.According to the important loads and common loads in the load management unit,the partition management mechanism is proposed to ensure the stable operation of important loads.Finally,the system security is evaluated by voltage security index,and the reward and punishment strategy is designed based on this.更多还原