scholarly journals Transient stability of power systems with non-linear load models using individual machine energy functions

Author(s):  
Hamid Elahi
Author(s):  
S.Ali Abbas Al-Mawsawi

<p>In recent years, studies have been investigated the effectiveness of UPFC and TCSC in increasing power transfer capability. However, the effectiveness of these FACTS devices in increasing power transfer capability when the load is non-linear has not been established in a comparative study yet. This paper will explore the steady-state performance of the UPFC and TCSC as impedance compensation models. The effectiveness of both FACTS devices are investigated when they are installed in multi-machine systems with different non-linear load models. Simulation results demonstrate that, upon installing UPFC, more active and reactive powers are received at the sending end bus for different types of non-linear load models. In addition, both active and reactive powers are more sensitive in changing the modulation index of the converters. Furthermore, both the active and reactive powers are less sensitive to the non-linearity of the load model type. However, active and reactive powers in case of installing TCSC are only sensitive in changing the firing angle (α) when it is between 90º to 110º. Therefore, results from this study clearly encourage the effectiveness of UPFC in comparison to TSCS in terms of increasing power transfer capability applied to non-linear load models. </p>


2020 ◽  
Vol 5 (1) ◽  
pp. 149-163
Author(s):  
Haider Muhamad Husen ◽  
Salar Ahmed Qadir

Unbalanced input source voltages generate extra current harmonics in addition to non-linear loads which distorts the power quality in the entire power systems. Three-phase multi-level neutral point clamped (NPC) converter based shunt active harmonic filter (SAHF) are used as a solution to overcome problems due to current harmonics. In this work, synchronous reference frame (d-q) algorithm is selected to detect the harmonic current components, Proportional-integral (PI) controller is utilized to ameliorate the storage of energy in the dc-link capacitor and the multilevel space vector pulse width modulation (MSVPWM) strategy determines the switching pulses of NPC inverter. Under balanced input supply voltages condition, the proposed MSVPWM achieved a mitigation of source current THD of 3.58 % as compared to 28.57 % prior to compensation on non-linear load. Furthermore, the MSVPWM technique was compared with and without compensation under unbalanced input source voltages and the results shows that the proposed method achieved reduction in source current THD of 3.96 % as compared to 29.76 % after and before compensation respectively. The proposed MSVPWM based-SAPF model was also compared with conventional SVPWM under balanced and unbalanced input supply voltages conditions. The results show that MSVPWM performed better than CSVPWM. The simulated results obtained by MATLAB/SIMULINK power system environment. All the results for the presented work are within IEEE-519 harmonics standard with non-linear loads under balanced and unbalanced voltages condition. 


Author(s):  
Aleksei V. Makarov ◽  
Valeriy G. Makarov ◽  
Tatiana V. Makarova ◽  
Aleksei A. Petrov

The purpose of the work is developing a simulation model of factory’s the power system, with a nonlinear load model, which is a 12-pulses thyristor invertor and a model of a static synchronous compensator, which is multi-level voltage invertor, based on H-bridge invertor. Also defining preliminary parameters for the design of a static synchronous compensator in order to meet the requirements for power factors and limits of voltage harmonic and interharmonic distortion specified for the point of common connection to the mains supply. The analytical and numerical methods of mathematical programming and control of electromechanical systems were used. VisualStudio and PSIM software products for developing a control system for electromechanical systems and compiling a simulation model of an industrial power supply system were used. As a result of the research, a simulation model of the power supply system of an industrial enterprise, a model of a nonlinear load and a static synchronous compensator were developed. The rated power of the static synchronous compensator is determined to reduce the consumption of reactive power and the magnitude of the higher harmonics of the current, at the point of common connection, during operating a non-linear load.


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