Identifying the efficiency decrease factor of motors working under power harmornic in 660V electric mining grids

Purpose. Identify the motors efficiency decrease factor corresponding to various values of load-carrying ratio. Methods. Basing on the onsite measurements of power harmonic in 660V low voltage (LV) grids in Vietnam underground mines, simulations have been done on MATLAB and compared with mathematical models. Verifying data will be implemented in Lab-measurements carried out on pumping system to reveal series of decreasing factors. Findings. Series factors present the relation of the level of power total harmonic distortion (THD) and the decrease in motor efficiency with alternative load-carrying ratio. The factors will help mine operators to have better understanding of the power harmonics impact on 660V motors. Originality. The proposed factors and simulation in MATLAB may be applied to all underground mining grids with diffe-rent input parameters of THD. Practical implications. The research is implemented to identify the factors obtained from the operation of motors which work in high power harmonic environment. The resulting factors could be utilized to recalculate mining efficiency.

Reducing the effects of Power Harmonics on Distribution Transformers using Simplex Optimization Technique

There have been incessant power failures in our power network, which has arisen as a result of over current, over voltage, harmonic distortion caused by ripples to mention a few, This could be overcome by determining the harmonic mean from a given harmonic distortion data ,optimizing the mean from a given distortion data, training the optimized result to minimize harmonic in power distribution transformer, designing a Simulink model for mitigating the resultant effect of harmonics which are the sinusoidal components of a complex wave, using simplex optimizationtechnique. The optimization technique used is 69% better than the conventional method like proportional integral derivative (PID) in terms of minimizing harmonic in power transformer.

Single-Phase Active Power Harmonics Filter by Op-Amp Circuits and Power Electronics Devices

This paper introduces a new structure for single-phase Active Power Harmonics Filter (APHF) with the simple and low-cost controller to eliminate harmonics and its side effects on low voltage grid. The proposed APHF includes an accurate harmonic detector circuit, amplifier circuit to trap tiny harmonics, switching driver circuit for precise synchronization, and inverter to create injection current waveform, which is extracted from reference signal. The control circuits are based on electrostatic devices consist of Op-Amp circuits. Fast dynamic, simplicity, low cost, and small size are the main features of Op-Amp circuits that are used in the proposed topology. The aim is removing the all grid harmonic orders in which the proposed APF injects an appropriate current into the grid in parallel way. The proposed control system is smart enough to compensate all range of current harmonics. A prototype is implemented in the power electronics laboratory and it is installed as parallel on a distorted grid by the non-linear load (15 APeak-Peak) to verify the compensating of harmonics. The harmonics are compensated from THD% = 24.48 to THD% = 2.86 and the non-sinusoidal waveform is renovated to sinusoidal waveform by the proposed APHF. The experimental results show a good accurate and high-quality performance.