Bøger af Besta Hariprasad

In this book, the application of the active SFCL into in a power distribution network with DG units is investigated. For the power frequency overvoltage caused by a single-phase grounded fault, the active SFCL can help to reduce the over- voltage¿s amplitude and avoid damaging the relevant distribution equipment. The active SFCL can as well suppress the short-circuit current induced by a three-phase grounded fault effectively, and the power system¿s safety and reliability can be improved. Moreover, along with the decrease of the distance between the fault location and the SFCL¿s installation position, the current-limiting performance will increase. During the study process, in view of the changes in the locations of the DG units connected to the system, the DG units injection capacities and the fault positions, the active SFCLs current-limiting and overvoltage suppressing characteristics are both simulated in MATLAB. The simulation results show that the active SFCL can play an obvious role in restraining the fault current and overvoltage, and it can contribute to avoiding damage on the relevant distribution equipment and improve the systems safety and reliability.

The size and location of DG are the crucial factors in the application of DG for loss minimization. This book presents an algorithm for the identification of bus location using Sensitivity analysis and also an algorithm for the determination of size of the DG using PSO. This methodology is tested on IEEE 15 bus system. By installing DGs at all the potential locations with the determined sizes, the total real power loss of the system has been reduced by 83% and the voltage profile of the system is also improved. The harmonics that are present in the system are reduced by placing capacitors at the optimal locations which are determined by using PSO-HPF algorithm. By placing the capacitors at optimal locations, the voltage profile is also improved.

An integral terminal sliding mode control design was proposed to enhance the power quality of wind turbines under unbalanced voltage conditions. The design combines the robustness, fast response, and high quality transient characteristics of the integral terminal sliding mode control with the estimation properties of disturbance observers. It was successfully implemented to both the rotor-side (RSC) and grid side (GSC) converters of a DFIG-based wind turbine. The controller gains were auto tuned using a fuzzy logic approach. Its performance was assessed in the presence of deep voltage sags and under varying parameter conditions. Its dynamic response was also compared to that of the standard SMC. The performance analysis and simulation results confirmed the ability of the proposed approach to maintain the active power, currents, DC-link voltage and electromagnetic torque within their acceptable ranges even under the most severe unbalanced voltage conditions.