孤立电网中风电和储能的联合非线性鲁棒控制

Combined Nonlinear Robust Control of Wind Powerand Energy Storage in Isolated Grids

为优化风储孤立电网的暂态特性以提升其在恶劣运行环境下的抗干扰能力,提出了孤立电网中风电和储能的联合非线性鲁棒控制策略。基于状态反馈精确线性化及鲁棒H∞最优控制理论,并综合考虑了系统建模时同步电机的转矩扰动、功率扰动、电压扰动等各种干扰因素,首先通过构造微分同胚非线性坐标变换,建立了风储孤立电网的精确线性化动态模型,进而设计了风电和储能的联合鲁棒控制器;所提控制策略可使风机实时地保持最优转速以输出最大风功率,并通过风电与储能的联合控制使系统出力跟踪负荷变化,实现了多目标控制。仿真验证表明,提出的风电和储能的联合非线性鲁棒控制策略对外界风速及负荷的扰动具有很强的鲁棒性;当外界风速突变或系统负荷突变时,风储孤网在非线性鲁棒控制器作用下可以迅速且平滑地过渡至稳态,有效避免了采用传统PI控制时调节过程中出现的超调及2~3次振荡,能显著提升风储孤立电网的暂态特性。该研究为风储孤立电网的联合控制提供设计理论基础及工程实践。

In order to optimize the transient characteristics of the isolated wind-storage power grid and enhance its anti-interference ability in harsh operation,a combined nonlinear robust control strategy of wind power and energy storage in isolated grids was proposed in the paper.Based on the state feedback exact linearization and robust H∞optimal control theory and taking into consideration various interference factors(for instance,torque disturbance,power disturbance,voltage disturbance of the synchronous motor)in the system modeling,an exact linearization dynamic model of the isolated wind-storage grid was established by constructing the diffeomorphism nonlinear coordinate transformation,and then a combined nonlinear robust controller of wind power and energy storage was designed.The proposed strategy can help the wind turbine maximize the wind power by maintaining the optimal revolution speed in real time and can keep power generation tracking the load change through the combined control of wind power and energy storage,realizing the multi-objective control.The simulation results show that the proposed combined nonlinear robust control strategy can hold strong robustness to external wind speed and load disturbance.When the external wind speed or the system load changes drastically,the isolated wind-storage grid can promptly and smoothly transition to the steady state under the action of the nonlinear robust controller,which effectively avoids the overshoot and 2—3 oscillations in the adjustment process when using the traditional PI control and significantly improves the transient characteristics of the isolated wind-storage grid.The research can provide a theoretical basis and engineering practice for the combined control of isolated wind-storage grids.