Optimal Design Method of Flexible Excitation System for Improving Power System Stability
Abstract : Providing sufficient damping over the full frequency range of low-frequency oscillation (LFO) is a challenge in modern power systems. The flexible excitation system with two damping channels, controlled by the power system stabilizer (PSS) and the reactive power damping controller (RPDC), respectively, provides a new way to solve this problem. The controller structures of the flexible excitation system are studied, in which a novel structure is adopted in RPDC to enhance the damping over the lower frequency range of LFO. The controller parameters design method of the flexible excitation system is also proposed: the phase compensation method is employed to design the time constants of PSS and RPDC; and the gains of them are adjusted based on their critical values. A single machine-infinite bus system in a real-time digital system and a system considering the doubly-fed wind generator are simulated to verify the effectiveness of the flexible excitation system on improving the power system stability.
? The computer implementation of such a scheme of economic dispatch is straightforward.
? It might be done by provision of tables of the values of FY as a function of the load levels and devising a simple scheme to take the existing load plus the projected increase to look up these data and compute the factors.
? Security enhancement: Recommends corrective control actions to be taken to alleviate an existing or potential overload in the system while ensuring minimal operational cost.
? The secondary reactor is normally nonexistent, as it is more economical to design the reactor transformer with 200% leakage impedance between primary and secondary windings.
? The conic programming is an effective tool to solve robust PSS design problems by simultaneously considering several operating scenarios is show in.
? Linear Matrix Inequality (LMI) is flexible in controller design since it provides an incredibly powerful way to solve convex or quasi-convex optimization problems.
? A PSS for a small-signal stability study using three kinds of controllers to solve the problem of the immeasurable state variables in the conventional sliding mode control is presented in, which the effectiveness of the proposed controller is verified by linear time-domain simulation under normal load operation and under parameter variation of AVR gain.
• The modified form of BPTT has been named Recursive Gradient (RG) and has used optimization of an objective function based on the current and previous state vector and control inputs.
• The results have proved that neuro-PSS trained on proposed algorithm had far better tracking capability than conventional PSS.
• The strength of the proposed controller has been depicted on multi machine system. The results have shown that the proposed controller has performed better in terms of overshoot, undershoot as well as damping.
• The research work proposed in [58] has used evolutionary algorithm and ANFIS. The control algorithm is based on self-tuning and offline-trained.
? Power system dynamic performance is improved by the damping of system oscillations. Generally, there are two kinds of power oscillation damping controllers in power systems: PSS and FACTS controllers.
? PSS is widely used in the electric power industry for improve the performance and functions of power systems during normal and abnormal operations.
? A PSS can be viewed as an additional block of a generator excitation control or automatic voltage regulator, added to improve the overall power system dynamic performance, especially for the control electromechanical oscillations.
? The gain and the lead-lag compensator time constants are to be selected for optimal performance over a wide range of operating conditions.
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