A high-resolution Subspace-Least Mean Square (S-LMS) method for harmonic and interharmonic measurement in power systems is provided. The eigenvector corresponding to the smallest eigenvalue is used to calculate the frequencies of the signal, and the least mean square method is used to estimate the amplitude and phase angle of harmonic and interharmonic components based on the computed frequencies and time domain measurements of the signal. Three schemes, namely sparsity, catch-and-pinpoint, and hybrid are presented. The S-LMS method provides accurate phasor, harmonic and interharmonic measurements for power system monitoring. The speed, accuracy, and resilience of the S-LMS method can be further increased by each of the three schemes. The method has a wide range of applications in power quality analyzers, synchronized phasor measurement, situational awareness, dynamic equivalencing, and smart meters.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
 This invention was made with government support under Contract No. DE-EE0003226, awarded by the Golden Field Office, U.S. Department of Energy. The government has certain rights in the invention.