A power system stabilizer (PSS) for a wind turbine employing a doubly fed induction generator (DFIG) is presented. It is shown that this PSS can significantly influence the contribution that a DFIG-based wind farm can make to network damping. A simple, generic test network that combines synchronous and wind farm generation is used to demonstrate system performance contributions. The results of both eigenvalue analysis and time response simulation studies are presented to illustrate contributions to network dynamic and transient performance that the DFIG controller with its PSS can make. Performance capabilities superior to those provided by synchronous generation with automatic voltage regulator and PSS control are demonstrated.

A power system stabilizer for DFIG-based wind generation

Design of augmented fuzzy logic power system stabilizers to enhance power system stability

This paper presents an augmented fuzzy logic power system stabilizer (PSS) for stability enhancement of multimachine power systems. In order to accomplish a satisfactory damping characteristic over a wide range of operating points, speed deviation (/spl Delta//spl omega/) and acceleration (/spl Delta//spl omega/) of a synchronous generator were taken as the input signals to the fuzzy controller. It is well known that these variables have significant effects on damping the generators' shaft mechanical oscillations. A modification of the terminal voltage feedback signal to the excitation system as a function of the accelerating power on the unit, is also used to enhance the stability of the system. The stabilizing signals are computed using the standard fuzzy membership function depending on these variables. The performance of the proposed augmented fuzzy controller is compared to an optimal controller and its effectiveness is demonstrated by a detailed digital computer simulation of a single machine infinite bus and a multimachine power systems.

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Design of augmented fuzzy logic power system stabilizers to enhance power systems stability

A power system control apparatus has a power system impedance estimating circuit for estimating a power system impedance from an internal power of a generator, determined by an internal current thereof, and from a terminal voltage of the generator, and having a power system impedance estimating table, a power system stabilizer for suppressing a power fluctuation in power system in accordance with the estimated power system impedance, and an auto voltage regulator for keeping an output voltage of the generator at a constant value during a normal operation.

Power system stabilizer estimating a power system impedance

This paper presents a study of fuzzy logic power system stabilizer (PSS) for stability enhancement of a single machine power system. In order to accomplish a stability enhancement., speed deviation (/spl Delta//spl omega/) and acceleration (/spl Delta//spl omega/~) of the rotor synchronous generator were taken as the input to the fuzzy logic controller. These variables take significant effects on damping the generator shaft mechanical oscillations. The stabilizing signals were computed using the fuzzy membership function depending on these variables. Simulink Block Design and Matlab 5.3 were utilized in implementing the study. The performance of the fuzzy logic power system stabilizer was compared with the conventional power system stabilizer and without power system stabilizer. The simulations were tested under different types of conditions; the steady state operation, three phase to ground fault, mechanical power input changes, generator loading and reference voltage (V/sub ref/) step changes.

Study of fuzzy logic power system stabilizer

The authors propose three novel approaches to improve a conventional power system stabilizer (PSS) in a single machine to infinite bus system. These improved stabilizers use the conventional PSS in the usual manner plus modification of the terminal voltage feedback signal to the excitation system as a function of the accelerating power on the unit. This nonlinear action increase the power system stability greatly. Also, since these improved stabilizers are based on the conventional stabilizers, they are simple to implement. Simulation results show that these three kinds of improved stabilizer can improve power system stability much more than the conventional PSS which has been used widely in power systems since the 1970s. >

M.M. Gupta

Papers

Improved power system stabilizers