The doubly-fed induction generator (DFIG) produces the reactive power to maintain its constant voltage operation. Firstly, the principle of the constant voltage control system for double-fed wind turbines is researched, and the influence on DFIG terminal voltage when the wind speed changes and the grid voltage sags is analyzed. Secondly, self-tuning PI control algorithm based on BP neural netwo...

Voltage sags normally do not cause equipment damage but can easily disrupt the operation of sensitive loads such as electronic Adjustable Speed Drives (ASD’s). Voltage sags cause a momentary decrease in DC-link voltage triggering an under voltage trip leading to nuisance tripping of adjustable speed drives (ASD’s) employed in continuous-process industries which contributes to loss in revenue. A...

The dynamic voltage restorer (DVR) is used to regulate the voltage at the load terminals from various power quality problems like sag, swell, harmonics, unbalance etc., in supply voltage. This paper presents modelling aspects of several types of Dynamic Voltage Restorer (DVR) working against various voltage sags by simulation in PSCAD/EMTDC. The reference signal for the series connected DVR is ...

This paper introduces the terminology and various issues related to ‘power quality’. The power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency deviations that result in a failure of end use equipment’s. The main occurrence of voltage sag is always considered as one of the major power quality problems and it become severe to industrial customers. Voltag...

Any power quality disturbance waveform can be seen as superimposition of various oscillating modes. It becomes necessary to separate different components of single frequency or narrow band of frequencies from a non stationary signal to identify the causes which contribute to power quality disturbances. In this paper a method is proposed to detect and classify voltage sag causes based on Empiric...

This paper describes the causes of voltage sags in affecting process industries, their impacts on equipment operation, and possible solutions. The definition proposed focuses on system faults as the major cause of voltage sags. The sensitivity of different types of process industry equipment; including adjustable speed drive controls, programmable logic controllers, and motor contactors; is ana...

Any power quality disturbance waveform can be seen as superimposition of various oscillating modes. It becomes necessary to separate different components of single frequency or narrow band of frequencies from a non stationary signal to identify the causes which contribute to power quality disturbances. In this paper a method is proposed to detect and classify voltage sag causes based on Empiric...