The Research On Harmonic Norton Model And Harmonic Source Identification Of Single-phase Diode Bridge Rectifier Loads

In recent years, single-phase nonlinear loads with bridge rectifier circuit have beenimmediately increasing with the development of power electronic technology as well asthe wider attention of energy saving. These loads are distributed all over the low voltagedistribution system, and increasingly becoming a new harmonic source that inducedscholar extensive concern as distributed harmonic sources. Although the power of asingle device is small, but it has high current distortion, some even more than100%.Numerous harmonic current of such nonlinear loads injected into the system, powerquality should not be underestimated. Based on the frequency domain admittanceharmonic model of the rectifier circuit load and its characteristics, this paper developeda harmonic Norton model, which simplified the load harmonic model, and developedthe main factors that affect the establishment of the harmonic Norton model. Thefeasibility of such nonlinear load harmonic Norton model is verified by a large numberof experiments. Based on this, harmonic Norton model parameters have used toresearch on harmonic source identification.①Based on harmonic coupling admittance matrix model of single-phase bridgerectifier circuit, influence factor of the bridge rectifier load harmonic Norton modelwere studied. Through theoretical analysis and simulation and experiment results showthat coupling relationship between input voltage and admittance elements of theadmittance model will directly impact the establishment of the load harmonic Nortonmodel.②According to harmonic self-attenuation characteristic of single-phase diodebridge rectifier loads, and input voltage crest factor embody flat characteristics was keyindex which influence the establishment of such non-linear load harmonic Nortonmodel. And it was verified by a large number of measured data. This also provides thebasis to construct the fluctuation quantity of the voltage and current to obtain harmonicNorton model. ③Capacitor switching method was applied to construct the fluctuation quantity ofthe voltage and current. Through fluctuation quantity method obtain utility side andcustomer side harmonic Norton model parameters, and using the parameters obtained toevaluate the respective harmonic responsibility on utility side and customer side.Simulation and experiment results show that capacitor switching method can estimateutility side harmonic Norton model parameters, however, customer side is not soeffectual, and the aberration will be directly reflected on the harmonic voltageresponsibility. Consequently, harmonic Norton model was applied to harmonic sourceidentification will affect the accuracy and credibility.