Novel quasi-decentralized SMC-based frequency and voltage stability enhancement strategies using valve position control and FACTS device

This paper proposes a novel sliding mode control (SMC) strategy for load frequency and voltage control in a complex power system under electrically faulty conditions. The load frequency regulation is achieved by changing the valve position of generators, while the bus voltage regulation is realized with the utilization of a popular FACTS device, Static Var Controller. Inter-area tie-line power is taken into consideration in the load frequency control so as to maintain the obligations of importing/exporting active power from/to connecting areas. The proposed control method thus operates in a quasi-decentralized manner, utilizing local frequency and voltage signals, as well as inter-area tie-line power information. An improvement is then made to the originally proposed SMC scheme to suppress its inherent fluctuations. The proposed enhanced SMC is easy to implement, and compared with conventional PI controllers, it produces superior performances in regulating frequencies and magnitudes of bus-bar voltages.