Abstarct: In recent years, by proliferation of non linear load in power network, power quality became of great importance for both consumers and utilities. One of the most important power quality events is flicker. Due to competition in power market, it is necessary to eliminate or reduce negative effects of flicker. Detection of flicker source’s place is the first step to mitigate flicker in power system. The core of flicker analysis is tracking of the voltage envelope. In this thesis, four methods baxsed on d-q transformation for tracking all flicker tones are proposed (novel method, improved square method, improved half wave rectifier method, and improved phase shifting method). The proposed methods are capable of tracking more than one tone in voltage envelope. Detection of flicker sources is an important problem in compensation issue. Many methods have been presented in the literature for detection flicker source such as power flicker method and Neural Network. But the problem of existence of several flicker sources using neural network has not been studied. In this thesis, improved half wave rectifier method is used to extract amplitude and angle of flicker tones and proposed three methods to detect several flicker sources in a power system. In the first proposed method, phase difference of voltage and current are considered as index of flicker sources detection and by using the fundamental power flow direction at any considered line as reference, and the flicker power sign, flicker sources have been detected correctly. In the second proposed method, flicker tones amplitudes are considered as index of flicker sources detection and biggest amplitude shows the place of flicker source. And in the third proposed method, in order to reduce the number of measurement devices a neural network is train by using acquired indexes (flicker tones amplitude) to identify the place of flicker sources. The performance of the d-q Transformation on tracking the flicker tones is examined with the signals generated by MATLAB, as well as the 6-bus network is simulated and algorithms for flicker sources detection are tested. The simulations results show that by using the proposed methods, all flicker sources in a power system can be detected correctly.