الفهرس 
chapter 1Only 14 pages are availabe for public view
 |  | from | 153 |  |  |
| | | from | 153 | | |
Abstract
Power quality has attached a great deal of attention in recent years due to an increasing utilization of sensitive power electronic based loads in power system. Power disturbances can cause severe damage to equipment and costly problems for customers. One of the most important steps for mitigating the effect of power quality disturbances is to classify these disturbances in the voltage and current waveforms. Only after disturbances classification is known, the disturbance mitigation can be carried out.
This thesis is built on three axes
• A hybrid technique for classifying power quality (PQ) disturbances is presented. The hybrid technique is based on Kalman filter for extracting three parameters (amplitude, slope of amplitude, harmonic indication) from the captured distorted waveform. Discrete wavelet transform (DWT) is used to help Kalman filter to give a good performance; the captured distorted waveform is passed through the DWT to determine the noise inside it and the covariance of this noise is fed together with the captured voltage waveform to the Kalman filter. The three parameters are the inputs to fuzzy-expert system that uses some rules on these inputs to classify the PQ event in the captured waveform. This hybrid technique can classify two simultaneous PQ events such as sag with harmonic or swell with harmonic. Several simulation and experimental data are used to validate the proposed technique. The results depict that the proposed technique has the ability to identify and classify PQ disturbances with high accuracy.
• Two novel modulated power filter compensation (MPFC) schemes for mitigating PQ disturbances are introduced. The proposed MPFC scheme A is a combination of one series capacitor and two shunt capacitors with a tuned arm power filter. The series capacitor is connected in series with the line conductors and two shunt capacitor banks are connected in parallel with the series capacitor terminals making delta connection. The AC side of six pulses rectifier are connected between the two shunt capacitors banks and the rectifier DC side is connected with a resistance and inductance branch that forms a tuned arm filter. The tuned arm filter is controlled by tri-loop error driven modified PID controller. The scheme B of MPFC is the same as scheme A but the two shunt capacitor banks make pi structure. The two schemes are validated by testing them on a simulated AC network of different types of loads and a comparison between the two schemes is achieved. The two schemes enhanced the power quality, improved power factor, compansated the reactive power, stabilized the buses voltag and reduced the transmission line losses. The MPFC scheme B is better than MPFC scheme A because the output waveforms are mor smooth than that of scheme A, specially in the power factor waveform, and the line losses is less than that of scheme A.
• The best modulated power filter compensator scheme of the two novel schemes is applied on a distribution network with wind energy source. With changing the wind speed and excursing the different loads, the MPFC scheme improves the performance results.