Reactive Power Meter Based On The Hilbert Digital Filtering Of The Design Study

Recently, the use of many inductive and nonlinear loads in power system bring on more and more serious unbalance of reactive power that result in power quality problem, such as voltage deviation and voltage flicker, which affect the safe operation of electrical network. And the reactive power measurement is the key for reactive power compensator, therefore fast and accurate reactive power measurement is the focus in electric measurement.The design principle of the existing power meter is based on the sinusoid circuit theory, and this kind of power meter is only suitable for the measurement of linear load electric energy of which voltage and current waveform is distortionless. However, along with the swift growth of non-linear elements in the power system, the characteristic of the power network and the load have been thoroughly changed, as well as the non-linear characteristic, the distortion and non-symmetry of current and voltage waveform get obvious. As a result, the sine electric circuit power theory presents unsuitability gradually.According to reactive power defined by Budeanu, a new algorithm of reactive power used Hilbert transform is proposed in this dissertation, based on system research on reactive power algorithm in the non-sinusoidal electric circuit. The Hilbert transform can shift 90°phase for each frequency and has no error in theory. Current and voltage are decomposed by orthogonal wavelet transform, and reactive power in each frequency band can be calculated in time domain. In order to compare various reactive power measure algorithms, simulation in MATLAB is completed by using non-sinusoidal signal models. the result shows that the algorithm of Hilbert transform have a highly precision when it is used to measure the reactive power.This dissertation proposes and simulates two kinds of Hilbert digital filter. By simulating in MATLAB, the result shows that the design of linear phase finite impulse response (FIR) Hilbert digital filter is more suitable than infinite impulse response (IIR) Hilbert digital filter in this high accuracy power meter's design. At last, this dissertation also designs the precise power meter's hardware and software. And the algorithm of reactive power based on the Hilbert digital filter is realized by two blocks (Embedded Target for the TI TMS320C2000^TMDSP Platform and MATLAB Link for CCS) on MATLAB. It is confirmed that it can obtain high accuracy and practicability by using DSP chip and the algorithm of the Hilbert digital filter in the course of this high accuracy power meter's design.