Power Frequency Waveform Analysis System Based On MATLAB And VB

Power Frequency AC Withstand Voltage Test, which imposes a certain voltage to the power equipments and maintains a certain time, to inspect the capabilities of electrical equipments insulation subjected to varieties of voltage. The voltage, waveform, frequency and the voltage insulation distribution in the internal goods of the AC withstand voltage test, under the actual operation requirements, we can effectively discovery the insulation defects of electrical equipments. Moreover, generally as the voltage of AC Withstand Voltage Test is higher than normal operation voltage, after the test, equipments have a larger safety allowance. Therefore, Power Frequency AC Withstand Voltage Test is the most effective and direct way to identify insulation strength of electrical equipments, as well as an important element of preventive test, and as an important tool to ensure the safe operation of electrical equipments.First, the author studied the feasibility of virtual instrument technology used in Power Frequency AC Withstand Voltage Test measurement. Then based on the virtual instrument, the author developed a power frequency waveform analysis system based on MATLAB7.1 and VB6.0, its main functions, including: electrical parameters measurement and signal waveform analysis. On the electrical parameter measurement facet, this digital waveform analysis system can calculate Root Mean Square(RMS), peak, active power, reactive power and power factor of voltage and current signals; on the signal waveform analysis facet, it can achieve waveform spectrum analysis, including: linear spectrum, power spectrum and energy spectrum, as well as can realize frequency spectrums real-time display function of voltage and current waveforms.Software is core of the whole power frequency waveform analysis system, this paper, based on MATLAB and VB mixed programming technology, used Client / Server programming to complete the whole waveform analysis system, utilized VB to complete the design of virtual instrument operation panel, used MATLAB to complete all the functions of the waveform analysis system, achieved seamless integration of MATLAB and VB. Also in the spectrum analysis aspects, this paper used the FFT improvement algorithm based on windowed interpolation. Through the simulation and test, we validated this algorithm, Comparing with the ordinary FFT algorithm, having greatly improved accuracy on harmonic analysis.On the hardware facet, this paper emphasized the feasibility of USB-9215A portable data acquisition card used in Power Frequency AC Withstand Voltage Test measurement, as well as emphasized the performance of the portable data acquisition card and application methods.At the end of this paper, the author established test circuit in the laboratory, set TDS3012B digital oscilloscope measurement results as the standard results, compared with the power frequency waveform analysis system measurement results. Through analyzing the measurement data, we validated the feasibility of this power frequency waveform analysis system based on MATLAB and VB, verified the advantages of MATLAB on numerical calculation and digital signal processing, proved the practical applicability of this power frequency waveform analysis system based on MATLAB and VB.