Classification of Power quality problems by wavelet Fuzzy expert system N.Karthik Electrical and Electronics Engineering, Bapatla Engneering college Bapatla, India, karthik_21199@yahoo.co.in Dr.Shaik Abdul Gafoor Electrical and Electronics Engineering, Bapatla Engneering college Bapatla, India Dr.M.Surya Kalavathi JNTU college of Engineering,Kukatpally, Hyderabad, India Abstract: Electric power quality, which is a current interest to several power utilities all over the world, is often severely affected by harmonics and transient disturbances. There is no unique model which can assess the power quality problem and to identify and classify them properly. Existing automatic recognition methods need improvement in terms of their versatility, reliability, and accuracy. The FUZZY LOGIC based tools have been applied for the PQ classification. This paper addresses Power quality problem classification by wavelet and fuzzy expert system. Major Key issues and challenges related to these advanced techniques in automatic classification of PQ problems are highlighted. New intelligent system technologies using DSP, expert systems, AI and machine learning provide some unique advantages in intelligent classification of PQ distortions. INTRODUCTION Modern power systems are complex networks, where hundreds of generating stations and thousands of load centers are interconnected through long power transmission and distribution networks. The main concern of consumers is the quality and reliability of power supplies at various load centers where they are located at. Even though the power generation in most well-developed countries is fairly reliable, the quality of the supply is not so reliable. Power distribution systems, ideally, should provide their customers with an uninterrupted flow of energy at smooth sinusoidal voltage at the contracted magnitude level and frequency. However, in practice, power systems, especially the distribution systems, have numerous nonlinear loads, which significantly affect the quality of power supplies. As a result of the nonlinear loads, the purity of the waveform of supplies is lost. This ends up producing many power quality problems. Apart from nonlinear loads, some system events, both usual (e.g. capacitor switching, motor starting) and unusual (e.g. faults) could also inflict power quality problems. Power quality problems are associated with an extensive number of electromagnetic phenomena in power systems with broad ranges of time frames such as long duration variations, short duration variations and other disturbances. Short duration variations are mainly caused by either fault conditions or energization of large loads that require high starting currents. Depending on the electrical distance related to impedance, type of grounding and connection of transformers between the faulted/load location and the node, there can be a temporary loss of voltage or temporary voltage reduction (sag) or voltage rise (swell) at different nodes of the system. Therefore, these power quality problems can be improved in distribution system by using custom power devices like DVR, D-STATCOM, and SSTC. SHORT-DURATION VOLTAGE VARIATIONS: Voltage variations, such as voltage sags and momentary interruptions are International Journal of Advances in Engineering Sciences Vol.1, Issue 3, July, 2011