Design Power System Stabilizer Based on Transient Energy Flow Theory

The parameter setting of power system stabilizer (PSS) is of great significance for the stability of the power system. Phase compensation methods are the current mainstream methods which are on the basis of the complex torque coefficient analysis. Since energy function and its changing rates directly reveal oscillation state of the power systems, this paper proposes a novel method for designing PSS controller from the energy function perspective. First, the theory of transient energy flow is introduced and expression of the dissipative energy flow is derived. Then, a small-signal model of synchronous machine (SM) containing the PSS is established. The input signal is the phase of the SM terminal voltage, and the output is SM's output active power. The transfer function between them is obtained. A definition of the SM's stability contribution index (SCI) is proposed. With the aim of making the value of the energy function decrease as fast as possible, the optimum phase-frequency characteristics of the transfer function can be gained. Thus, the PSS parameter design model is built. Intelligent calculation algorithms can be used to solve it. Finally, the effectiveness of the proposed PSS design technique has been evaluated by simulation on the single-machine infinite-bus system and the four-machine two-area system.