A New Fuzzy-Based Total Demand Distortion Factor for Nonsinusoidal Situations

When considering one single range of short circuit level, the values of ldquototal demand distortionrdquo (TDD) are enough to quantify harmonic distortion in a certain current waveform. When considering multiple ranges of short circuit levels the TDD is unable to determine whether the distortion is within the acceptable limits or not. In this paper, a new fuzzy total demand distortion factor (FTDDF) is proposed. The FTDDF indicates the level of distortion in the current waveform or (how close is the waveform to a pure sinusoidal waveshape,) and also allows deciding whether the distortion contained in the current is within the acceptable limit or not. Moreover, the use of a fuzzy inference system (FIS) has the advantages of being simple, easy to implement and contains its knowledge base. The proposed FTDDF is sensitive to the TDD and short circuit level changes in all distortion cases in sinusoidal and nonsinusoidal situations. Therefore it will be very useful for many applications such as power-quality (PQ) evaluation, cost-benefit analysis of PQ mitigation techniques and setting penalty tariffs for customers generating harmonics.