Algorithm Researching On Voltage Sag Characteristics Detection

With rapid updating and highly automatization of technologies in electric equipments, Voltage sags, as the most important dynamic power quality(PQ) problem has brought forth widely attentions. And customers also have stricter demands on PQ. To decrease the impacts of sags as much as possible, the principal task is to introduce fast, effective and accurate algorithm for Voltage sags characteristics detection.Problems concerning voltage sag, disunity standards on sags characteristics and indices are generally introduced in the thesis. For the short duration and randomicity of sags happening, traditional methods for Voltage sags characteristics detection are inadequate to give complete parameters. It is naturally to introduce more practical and novel algorithm -A algorithm for Voltage sags characteristics detection using wavelet transform and DQ transform. Wavelet's superiority in denoising and detecting odd point in signal has been fully exploited. The beginning and ending time of the sag are exactly determined. Signal with less noise is analyzed using DQ transform to get magnitude and duration of the sag. Thus all the sags characteristics are detected accurately. The simulation results of two typical sag signals prove the validity of the algorithm.The thesis also probe into the implement of wavelet in DSP, which the main obstacle in wavelet practical using. The summary and the prospect of the methods for sags detection are given finally.