Optimal Power System Stabilizer Based Enhancement of Synchronizing And Damping Torque Coefficients

Design of power system stabilizer for enhancement power system stability is proposed. The effect of the proposed PSS on the synchronizing and damping torque coefficients is proved. To study the effectiveness of the proposed linear quadratic regulator (LQR) power system stabilizer, a sample power system in a linearized model is simulated and subjected to different operating conditions. The Linear Quadratic Gaussian (LQG) power system stabilizer is proposed. The power system dynamic responses after applying a variety of operating points with the proposed LQG-PSS stabilizer are plotted. The output of such stabilizer is fed directly to the automatic voltage regulator (AVR) of the synchronous machine. The input to such stabilizer are four state variables, two are accessible which are the deviation of the speed ( ω Δ ) and rotor angle ( δ Δ ). The other two inaccessible states that are the deviation of the Voltage proportional to q-axis flux linkage. ( ' q E Δ ) and the Generator field voltage ( fd E Δ ). An observer has been designed to access the two inaccessible states. Further, the effect of connecting the proposed power system stabilizer on synchronizing and damping torque coefficients is tabulated. A comparison between the effect of the power system stabilizer based on either LQR approach, the proposed LQG stabilizer in terms of either power system responses or its eigenvalues due to different load condition is reported. Key-Words : Power Systems, LQR Control, LQG Power System Stabilizer. List of symbols: Is the rotor angle (Rad.) Is the rotor speed (pu.) Is the mechanical power (pu.) Is the self damping coefficient (pu.) Is the inertia constant in (s) Is the quadrature axis voltage(pu.) Is the excitation voltage (pu.) Is the direct axis reactance (pu) Is the transient direct axis reactance (pu) Is the direct axis short circuit time constant (s) Is the exciter time constant (s) Is the exciter gain (pu.) Is the optimal control gain Is the system matrix Is the state variables Is the input matrix