“S”区水力瞬变下抽水蓄能机组低水头并网及调频优化控制研究

The inherent “S” characteristic of pump-turbine results in dynamic catastrophic phenomena such as hydraulic vibration, mechanical instability and electromagnetic oscillation in the process of no-load grid connection and frequency modulation under low-head. In order to improve robustness and control performances of the turbine governing system, an efficient solution scheme for two dimensional dynamic nested flow-speed iterations is proposed by taking the precise system modeling as a breaking point. Implicit fractional-order differential equation set of multi-dimensional state variable topology and fractional-order model of hydraulic-mechanical-electric coupled system are built by studying on hydraulic transient mechanism of “S” area. Subsequently, the eigenvalue and stability condition of the Jacobi matrix of fractional-order chaotic controlled system at the equilibrium point are derived from analysis of nonlinear dynamic chaotic response characteristics of the system under dynamic catastrophe. Furthermore, a feedback robust predictive control strategy for fractional-order chaotic system under no-load grid connection condition is proposed. In addition, by investigating the interaction mechanism between self-excited vibration and low frequency oscillation, a primary frequency regulation method based on intelligent parameter optimization and model predictive control has been proposed. Eventually, a distributed multi-objective cooperative robust control model based on primary frequency modulation and AGC is established. The research findings will perfect the optimization control methodology of no-load grid connection and frequency modulation, thus to improve the intelligent operation level of pumped storage power stations.

水泵水轮机固有的“S”特性，导致抽水蓄能机组在低水头空载并网与调频过程中存在水力振动、机械失稳与电磁振荡等动力灾变现象，机组控制呈现高度复杂特性。为提高调节系统的鲁棒性与控制品质，以机组精确建模为突破点，以“S”特性区复杂水力瞬变机理研究为基础，提出流量-转速二维动态嵌套迭代高效求解方法，推求包含多维状态变量的拓扑结构隐式分数阶微分方程集，建立水-机-电耦合系统分数阶模型；解析动力灾变下系统非线性动力学混沌响应特性，推导分数阶混沌受控系统的雅可比矩阵在平衡点处的特征值和稳定条件，提出空载并网工况分数阶混沌系统预测反馈鲁棒控制方法；探明水力-机械自激振动对低频振荡的作用机理，提出融合调频参数智能优化与模型预测控制的一次调频控制方法，建立一次调频与AGC双智能体分布式多目标鲁棒协同控制模型。研究成果将系统完善机组空载并网与调频工况的优化控制方法体系，提高我国抽水蓄能电站智能化运行水平。

本项目围绕抽水蓄能机组低水头空载并网及调频优化控制涉及的关键科学问题，开展了机组耦合系统精确建模、空载工况并网控制方法与调频优化控制三方面研究。首先，推求了不同控制模式下机组数学模型微分方程集，建立了包含高阶发电机与励磁系统的机组分数阶模型，提出了基于变分模态分解和引力搜索的一体化在线辨识方法；在此基础上，引入了Hopf分岔理论，解析了低水头区域运行时水力、机械、电气因素之间的非线性动力学耦合特性及敏感性，提出了工况自适应预测-模糊控制方法，该方法调控的机组频率的近似周期振荡次数和超调指数分别小于1次和2%；解析了机组一次调频工况振荡特性与稳定性，机组低水头一次调频失稳时，低频振荡出现在开始时刻、超低频振荡则贯穿整个过程；进一步，设计了一种模糊分数阶PID控制器，引入多目标算法联合优化输出隶属度函数与控制器参数，一次调频工况的频率波动峰值减小了5.7%，调节时间短了3~5s，取得了较好的控制效果；最后，基于劳斯-赫尔维兹稳定性判据方法，解析了一次调频工况下机组调速系统平衡点位置、机组出力变化与控制参数之间的关系，为一次调频与AGC协同控制提供了理论支撑。通过凝练总结项目研究成果，发表了SCI论文12篇，出版了学术专著2部，授权了发明专利1项，申请发明专利3项，获得省部级科技奖励二等奖1项、三等奖1项。项目研究实施期间，受项目资助，培养2名硕士研究生完成硕士学位论文答辩。项目成果在我国抽水蓄能电站获得集成应用，提高了机组空载并网成功率和调频运行稳定性，取得了显著的经济效益与社会价值。