A Coordinated Control Scheme of PSS and STATCOM Devices for Improving Power System Oscillation

In this present era, the continuously increment in power demand results expansion of power system network which makes the existing system more sensitive and prone to instability. An important issue associated with the stability of multi-area power system is the inter-area oscillations from a multi-machine system. Generally, Power System Stabilizer (PSS) are used for power system oscillation damping, but local PSS not have global observability so Flexible AC Transmission System (FACTS) devices with supplementary controller are used for effective damping of power system oscillations. In this paper, presents the coordination control of PSS and STATCOM to damp out the inter-area oscillations from a multi-machine system. In the past era, to damp out such type of inter-area oscillations used PSS as a local controller in multi-machine system. Reactive FACTS devices, such as static synchronous compensators (STATCOM) are considered and assessed for their damping controller design. STATCOM is reactive power compensator based upon a voltage source converter which uses power electronic devices with turn-off capability as switching devices. Its main function is to support bus voltage of which it is connected to the system by providing quick response to supply or absorb reactive power. For damping power oscillations purpose, it is required to employ power oscillation damping (POD) function wherein its output is summed to voltage reference as input of STATCOM. This paper focuses on implementing POD function in STATCOM controller to damp inter area oscillations mode. Some simulations results are carried out on Kundur Two-Area Four Machine system under small disturbance. From the simulation results, it reveals that the proposed controller damp-out the inter-area oscillations effectively under small disturbance conditions.