Partial Discretization-based Efficient Computation of H∞ Norm for Power System With Inclusion of Time Delays

Abstract

The application of wide-area measurement system and time delays in the transmission of remote signals make the traditional power system into delayed power system. Since the H∞ norm of delayed power system, which is usually expressed as the stability and performance criteria in the field of robust control, is difficult to be calculated directly by the traditional method, an efficient method for calculating H∞ norm of delayed power system is needed. In this paper, a partial discretization-based efficient computation method for H∞ Norm of delayed power systems is proposed. The model of the closed-loop delayed power system is established in consideration of time delays and the state variables are partitioned according to whether the state variables are correlated with time delays. Partial discretization is utilized to discretize retarded state variables only, which makes the order of state matrix after discretization close to that associated to power system without time delay and ensures the calculation efficiency of the presented method. Based on the model of closed-loop power system after discretization, the level set method is utilized to calculate the estimated value of H∞ norm and the estimated H∞ norm can be corrected by the correction equation, which guarantees the accuracy of the presented method. The test on the two-area four-machine system validates the efficiency and accuracy of the presented method, especially in the case of large time delay.