Power quality is generally indicated by stability, symmetry and current wave characteristicsand so on. As more modennonlinear loads are connected to the grid, the power quality has been seriously affected. The mass application of various power electronic devices and the frequent fluctuation of the loads are main sources of the disturbance which results in many negative impacts to the grid:
As more modennonlinear loads are connected to the grid, the power quality has been seriously affected.
- Low power factor, high power loss, high productive cost and low productive efficiency.
- Resulting in reactive power impact , voltage dropping and voltage flicker of the grid. In some cases even causing the driving and protection equipments‘malfunction or shutdown.
- Causing harmonic currents which may lead to:
- Grid voltage distortion.
- Faults of protective and automatic equipments.
- The amplification of resonanceand harmonic currents of the capacitors, which may lead to the capacitors’overload or over-voltage or burning.
- Increasing loss of transformers which will result in heat increase of the transformer.
- Heat increase of the electrical equipments, the instability of motor and even burning of the motor.
- Acceleration of insulation deterioration of electrical equipments.
- Reduction of efficiency of the electric arc furnace (EAF) and increment of losses.
- Disturbing communication signals.
- 3-phase unbalance which causes negative-sequence current which causes vibration of motor rotors.