Damping of inter area oscillations using power system stabilizer and unified power flow controller
Indreshwar Prasad Srivastava
Oscillation occurs in power system as a result of conditions such as faults or sudden changes in load or generation. These are harmful to the operations of the system since they affect power system stability and the flow of optimal power through it. These oscillations does not generally damp out in tie-lines by its own even the tripping of these lines can’t result in damping of these oscillations, unless some controls are applied to the system. Local and inter area mode of oscillations have conventionally been controlled by the use of Power System Stabilizers (PSS). However FACTS (Flexible alternating current transmission systems) controllers such as UPFC (Unified power flow controller) have sufficient strength as an alternatives to PSS. In addition to steady state solutions such as voltage control at bus and power flow control in transmission line, an additional benefit of FACTS controllers is that they can control power system oscillations in transmission system. These oscillations can damage generators, increases line losses and damage of power system components. The main aim of this thesis is to damp inter-area power system oscillations by the use of UPFC (Unified power flow controller). The approach proposed is a general nonlinear method for multiple FACTS controllers for damping power system oscillations in a power system. UPFC controllers can be used for fast damping of inter-area oscillations in both two-area and multi-area power systems.By using a UPFC the oscillation introduced by the faults, the rotor angle and speed deviations can be damped out quickly than a system without a UPFC. In multi area system with more than one FACTS controller are analysed during faults and also the response of these controllers in such conditions can be analysed.