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The purpose of this paper is to present a novel combined design of the voltage source converter–high voltage direct current (VSC-HVDC) and the power system stabilizer (PSS) controllers to obtain a better dynamical response. The proposed technique is applied to enhance the damping of the power system low-frequency oscillations (LFOs) and results are compared with traditional design. A fuzzy logic controller is designed for PSS (FPSS). Then, a chaotic optimization algorithm, which has a strong ability for finding the most optimistic results, is employed, in presence of FPSS, to search for optimal VSC-HVDC output feedback controller parameters. Moreover, a singular value decomposition method is utilized to select the most effective damping control signal of the VSC-HVDC output feedback controllers. The novel proposed controllers are evaluated on an AC/DC power system. The simulation results demonstrate that the combined controllers have an excellent capability for damping power system LFOs and greatly enhance the dynamic stability of the power system. Also, the system performance analysis under different operating conditions and some performance indices show the effectiveness of the proposed controllers. The benefit of the suggested procedure is greatly improving the dynamic response of the system. In addition, the overshoots, undershoots and the settling times are dramatically reduced by applying the proposed method.

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A comprehensive comparative study is made of a pitch control system and shunt flexible AC transmission system (FACTS) devices in order to improve large wind farm operation. Transient stability analysis of a large wind farm in the presence of superconducting magnetic energy storage (SMES), static synchronous compensator (STATCOM), static var compensator (SVC) and pitch controller is performed. The proposed control strategy of the STATCOM is based on PWM control; both the angle and the magnitude of the converter output voltage and the proposed SMES control system is based on a PWM voltage-source converter and a two-quadrant DC–DC chopper using an insulated-gate bipolar transistor (IGBT). Furthermore, robust control systems are designed for SVC and pitch controllers. To investigate the operation of the wind farm with contribution of these devices, two scenarios are considered and simulated. First, extensive analysis of a symmetrical three-phase fault and its effects on system operation is carried out. A permanent fault due to unsuccessful reclosing is analysed; this is one of the most noticeable features of this study. PSCAD/EMTDC software is used for modeling and simulation of the system components and proposed control strategies for power electronic interfaces. System performance analysis under different operating conditions and performance indices show the effectiveness of the proposed controllers even when a severe fault is applied.

In this paper, a robust method for the simultaneous coordinated design of the interline power flow controller (IPFC) and power system stabilizer (PSS) based on output feedback controllers in a single-machine infinite-bus power system for the enhancement of power systems low-frequency oscillations damping is presented. The Honey Bee Algorithm, which has a strong ability to find the most optimistic results, is employed to search for optimal IPFC and PSS output feedback controller parameters. A singular value decomposition method is utilized to select the most effective damping control signal of the IPFC output feedback controller. To assess the effectiveness and robustness of the proposed method, simulation studies are carried out for three operating conditions. Analysis of the results shows that the combined design has an excellent capability for damping a power system's low-frequency oscillations. Moreover, system performance analysis under different operating conditions and performance indices shows the effectiveness of the proposed method even when a severe fault is applied.