传统电压控制多采用潮流方程,电压可能在到达事故后稳定运行点前的过渡过程中失稳,因此基于系统的动态模型进行电力系统电压控制十分必要。该文提出了一种基于动态降阶模型的非线性电压预测控制方法。为降低优化计算时间,结合电力系统的特点对经验Gramian平衡降阶方法加以改进,并应用改进的经验Gramian平衡降阶方法降低电力系统非线性动态模型的维数。为提高模型计算精度和数值稳定性,提出使用4阶收敛的Adams法替代欧拉法进行状态预测,建立基于降阶模型的多步预测-滚动优化模型。此外,在模型求解过程中使用温启动方法和较小的迭代次数限值N~(max)来减少迭代次数。以NewEngland 10机39节点电力系统对所提出的方法进行验证。结果表明,所提出的方法能够提高预测模型的数值稳定性,极大地降低模型求解时间,有利于提前响应系统中可预测的动态变化,维持系统电压稳定。
Due to the use of power flowequation in tradition voltage control,the voltages may lose its stability in the transition process form the failure to the stable operating point. It is necessary to consider dynamic model of power system in voltage study. This paper presents a nonlinear voltage predictive control method based on dynamic reduced model. In order to decrease the optimal calculating time,the improved empirical Gramian balance reduction method based on the features of power system is applied to reduce the order of power system nonlinear dynamic model. In order to improve the accuracy and numerical stability of predictive model,this paper uses a 4-order convergent Adams method instead of Euler method to predictive state values,and develops a multi-step prediction and rolling optimization model based on reduced model. In addition,the warm start technique and a small iterative times limit N~(max)are used to decrease the iterative times in the solving process. The NewEngland 10-generator and 39-bus power system is simulated to test the performance of the proposed method. The simulation results showthat this method can not only increase the predictive model numerical stability and decrease the optimal-timing greatly,but also respond the predictable dynamic change of the system in advance to keep voltage stable.