Mehrdad Tarafdar Hagh; Seyyed Jalal Kazempour
Abstract
Although many mathematics-based and heuristic approaches have been recently developed on optimally allocation of TCSCs for lines overloads reduction and buses voltage stability enhancement during fault conditions, the works on the TCSCs efficiency to achieve the abovementioned goals are rare. This idea ...
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Although many mathematics-based and heuristic approaches have been recently developed on optimally allocation of TCSCs for lines overloads reduction and buses voltage stability enhancement during fault conditions, the works on the TCSCs efficiency to achieve the abovementioned goals are rare. This idea that TCSCs can surely enhance the system’s security must be comprehensively investigated. In this paper, after the optimal allocation of TCSCs, their efficiencies on lines overloads reduction and buses voltage stability enhancement during fault conditions are investigated using two new indices named “transmission index” and “voltage stability index”. The numerical results show TCSCs can remarkably enhance the buses voltage stability, but they can not significantly reduce the lines overloads. In addition, the impact of TCSCs installation on mitigation of load shedding aim to enhance the buses voltage stability is presented as a new work. The IEEE standard 14 and 30 buses systems are selected as case studies.
Hassan Taghizadeh; Mehrdad Tarafdar Hagh
Abstract
This paper presents a new method to find the optimum switching angles in voltage source multilevel converters in order to minimize specific higher order harmonics and decrease the total harmonic distortion (THD) of their output voltage waveform. The output voltage waveform of inverter can either be in ...
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This paper presents a new method to find the optimum switching angles in voltage source multilevel converters in order to minimize specific higher order harmonics and decrease the total harmonic distortion (THD) of their output voltage waveform. The output voltage waveform of inverter can either be in the form of staircase or PWM. In order to increase the degrees of freedom and elimination of more harmonics, one can increase the number of levels or use PWM waveform which has more switching than once at each level. However, both of them result in complexity of nonlinear transcendental equations which solving them by using conventional numerical iterative techniques such as Newton-Raphson method is not feasible. In this paper, particle swarm optimization algorithm is presented to find optimum switching angles of PWM waveform in multilevel converters. These angles must be determined so that the desired fundamental harmonic is maintained and at the same time undesired higher order harmonics are suppressed. Theoretical and simulation results for an eleven-level converter show the efficiency of the proposed algorithm to determine the optimum angles in order to decrease the undesired harmonics and produce very high quality output voltage waveform.
