Load Frequency Control of Power Systems with Governor Deadband (GDB) Non-linearity

Abstract

Load frequency control of power systems with a governor deadband (GDB) is studied in the paper. The effects of GDB on the linear active disturbance rejection controller (LADRC) are analyzed first. It is shown that the limit cycle can be avoided by reducing the controller and/or observer bandwidth. However, the disturbance rejection performance will be degraded. To maintain the performance of the original LADRC controller, two anti-GDB schemes are proposed. One is based on the observer structure of active disturbance rejection control, which utilizes the output of the governor to reconstruct the input to the system in order to correctly estimate the controller states. Another is based on the error between the realistic output of the governor and its ideal value which is fed back and added to the output of the original LADRC. Simulation results on a single-area and a two-area power system with the GDB show that the two schemes are effective in reducing the limit cycle caused by the GDB. The observer-based anti-GDB has some limitations in practical implementation and performance, while the error-compensation-based scheme is simple to implement and can approximate the disturbance rejection performance of the original LADRC.