Sampled‐data‐based H∞ load frequency control for power systems with wind power

Abstract

AbstractLoad disturbances, the intermittent generation of wind power, and the uncertainty of sampling period will significantly affect the frequency stability of power system. This paper presents a sampled‐data‐based load frequency control (LFC) scheme for power systems with wind power (PSWPs), which aims to guarantee the stable operation of the systems under a sampling period as large as possible while retaining the desired robust performance. First, by considering the feature that power system plant operates in continuous‐time domain and LFC controller operates in discrete‐time domain, the closed‐loop PSWPs installed with a PI‐type LFC controller is modeled as sampled‐data control system with aperiodic samplings. Second, by utilizing an augmented two‐side looped Lyapunov functional and the linear matrix inequality (LMI), two sampling‐interval‐dependent stability criteria with less conservatism are derived for the studied systems, which guarantee that the presented LFC scheme operates in a large sampling period. Then, based on proposed stability condition, a sampled‐data‐based PI‐type LFC controller with the consideration of sampling period and performance index is obtained. Following this, an algorithm is given to obtain the gain of sampled‐data‐based PI‐type LFC controller and the admissible maximum sampling period while preserving the desired robust performance. Finally, case studies are carried out on the one‐area power system and three‐area PSWPs. The simulation results demonstrate the effectiveness of the presented LFC scheme, and robustness against load disturbances, wind power fluctuations and sampling period. It also shows that the designed LFC scheme can tolerate a larger sampling period while preserving the desired performance.