Enhancement of Power System Transient Stability by Utilizing Controllability of Kinetic Energy of Adjustable Speed Synchronous Condensers

Worsening of power system transient stability is concerned in a power system where renewable energy resources increase and synchronous generators (SG) decrease. One of the measures to enhance transient stability is synchronous condensers (SC). We showed that SC decreases acceleration energy by the kinetic energy storage function of inertia and increases deceleration energy area by voltage control function. SC can enhance transient stability by these two effects. However, since the rotor speed of SC is fixed, SC cannot control kinetic energy. So, we turned our attention to adjustable speed synchronous condensers (ASSC) capable of controlling kinetic energy. This paper proposes a control method of ASSC for the enhancement of transient stability utilizing the controllability of kinetic energy of ASSC in the situation where ASSC exists between a large SG and load. A simulation result shows that ASSC increases the active power output of the SG during a fault and after clearing the fault by the proposed method compared with SC. As a result, the method can decrease the acceleration energy of the SG, increase the deceleration area of the SG and enhance transient stability.