Adaptive wams-based secondary voltage control

Voltage instability is a growing threat to the security and the reliability of power grids, especially as the penetration level of intermittent renewable energies increase significantly in recent years. Voltage instability and even voltage collapse will take place as the loss of control of the voltage profiles in a power system. To achieve more efficient voltage regulation in power systems, the hierarchical three-level coordinated voltage control mechanism has been developed recently to prevent voltage collapse through the appropriate management of reactive power sources. This chapter presents recent developments in adaptive secondary voltage control (SVC) by utilizing real-time measurements of power systems obtained from the wide-area measurement system (WAMS). These methods are adaptive in the sense that load disturbances are estimated from synchronized phasors of WAMS in nearly real-time. Thus, these control inputs of SVC can be synthesized to minimize deviations in load voltage profiles under the worst-case scenario. Uncertainties in measurement are also taken into considerations by exploring the maximum likelihood (ML) method to further improve SVC performance. Comprehensive simulations on a variety of IEEE benchmark systems have been performed to verify the feasibility and the effectiveness of these schemes.