A Novel Algorithm of Dielectric Loss Measurement Based on Orthogonal Decomposition
Chengjun Huang · Proceedings of the CSEE · 2008
The advantages and disadvantages of recent digital algorithms of dielectric loss,which include zero cross point voltage comparison,harmonics analysis and so on,are reviewed. Then signification and definition of dielectric loss factor-tanδ is analyzed under harmonics exist. Further more,voltage and current are defined as vectors in Euclid function space,and according to orthogonal characteristic,the current signal is decomposed to a total of active and reactive current. Subsequently,a novel digital algorithm of tanδ measurement is presented based on orthogonal decomposition,and this algorithm has properties such as clear physical signification,simple calculation,precise and steady measurement result. At last,the proposed algorithm is simulated under such conditions as sinusoidal voltage,nonsinusoidal voltage,frequency fluctuation,sampling frequency and sampling time length in change. Comparing with harmonics analysis method,simulation results show that the maximal measurement error is reduced to 23.72 percent and 5.35 percent respectively when voltage frequency fluctuates in (50±0.5) Hz. Meanwhile,the fluctuation scope of real-time measurement value of tanδ is reduced 110 times when frequency is 50.5 Hz. So the proposed method can be used in tanδ online monitoring and offline measurement.