2results about How to "Implement adaptive selection" patented technology

The application discloses a kind of electric meter relay resonance fault detection method and system based on harmonic analysis, it is related to the field of measurement electric variable, method includes: obtaining current signal and voltage signal and pre-processing, obtain the current cycle of current analysis signal and power grid harmonic spectrum;Based on power grid harmonic spectrum, the resonance risk of power grid is quantified, and the resonance sensitivity index of current cycle power grid is obtained;Pre-set candidate wavelet basis set, obtain the time-frequency focusing ability evaluation index and task adaptability index of each candidate wavelet basis in set;Based on three indexes, construct dynamic comprehensive cost function and select optimal wavelet basis;Based on optimal wavelet basis, wavelet packet decomposition is carried out to current analysis signal, and the current working state of relay is extracted fault feature and identified to judge.The application can realize the adaptive selection of wavelet basis, solve the problem that fault feature extraction is not accurate, false positive rate is high, and computing resource is not reasonably utilized in existing detection method.

The present application relates to a kind of multi-frequency impedance measurement methods based on frequency adaptive selection, it is related to power electronic converter impedance measurement technical field, including: according to measurement requirement given frequency range, and set iteration number and initial point number, generate initial impedance measurement frequency point set;Adaptive selection impedance measurement frequency point is through interpolation error calculation algorithm and dynamic average threshold method;All new impedance measurement frequency points are grouped according to odd-even, and the multi-sine signal of two groups of sub-frequency band amplitude is injected into the system to be measured;Based on the impedance data corresponding to all iteration cumulative impedance measurement frequency points, impedance curve is fitted by bilinear mapping and least square method.The present application can realize the adaptive selection of measurement frequency point, solve the problem that the peak or valley of impedance cannot be accurately observed in the traditional equal-frequency interval impedance measurement mode, and can provide important standardized tool and research background for system impedance acquisition and stability analysis.