Improving transient stability of power systems by using passivity-bassed nonlinear STATCOM controller

Reddy, D Raghu Rama (2007) Improving transient stability of power systems by using passivity-bassed nonlinear STATCOM controller. MTech thesis.



This report presents a novel nonlinear control scheme for designing Static Synchronous Compensators (STATCOM). A passivity-based approach is proposed for designing robust nonlinear STATCOM controller. The mathematical model of STATCOM will be represented by a Euler-Lagrange (EL) system corresponding to a set of EL parameters. The STATCOM modeled in the a–b–c reference frame are first shown to be EL systems whose EL parameters are explicitly identified. The energy-dissipative properties of this model are fully retained under the d-q axis transformation. By employing the Park’s transformation, the differential geometry approach is used to investigate the power system dynamics with considering STATCOM under the synchronous d-q frame. Based on the transformed d-q EL model, passivity-based controllers are then synthesized using the technique of damping injection. Two possible passivity-based feedback designs are discussed, leading to a feasible dynamic current-loop controller. Motivated from the usual power electronics control schemes, the internal dc-bus voltage dynamics are regulated via an outer loop proportional plus integral (PI) controller cascaded to the d-axis current loop. The STATCOM controller based on passivity is obtained with a feedback control law from linear system models. The STATCOM controlled by the proposed passivity-based current control scheme with outer loop PI compensation has the features of enhanced robustness under model uncertainties, decoupled current-loop dynamics, guaranteed zero steady-state error, and asymptotic rejection of constant load disturbance. Digital computer simulation for a large operation point variations have been studied the STATCOM controller design. For analysis of the system performance, the PSCAD/EMTDC programme was applied. Simulation results show that the proposed STATCOM controller can effectively enhance transient stability of the power system even in the presence of large operation point variations.

Item Type:Thesis (MTech)
Uncontrolled Keywords:STATCOM, EL, PSCAD/EMTDC
Subjects:Engineering and Technology > Electrical Engineering > Power Systems
Divisions: Engineering and Technology > Department of Electrical Engineering
ID Code:4318
Deposited By:Hemanta Biswal
Deposited On:10 Jul 2012 11:40
Last Modified:10 Jul 2012 11:40
Supervisor(s):Panda, P C

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