Quantitative analysis method of harmonic voltage transmission level of nonlinear load of user terminal and device

Abstract

The invention provides a quantitative analysis method of a harmonic voltage transmission level of a nonlinear load of a user terminal and a corresponding device. The method comprises the steps: sampling voltage and current in a common coupling point between a power supply terminal and the user terminal; obtaining several harmonic voltage phasors and current phasors according to sampling data; judging whether the nonlinear load of the user terminal is a main harmonic source or not; computing the harmonic impedance of the power supply terminal if the nonlinear load of the user terminal is the main harmonic source; and computing the harmonic voltage transmission level of the nonlinear load of the user terminal in a time interval according to the harmonic impedance of the power supply terminaland the current phasors in the common coupling point. By applying the method, the harmonic voltage transmission level of the nonlinear load of the user terminal can be easily and quantitively analyzed.

Description

technical field [0001] The invention relates to an analysis method and device for electric system parameters, in particular to an analysis method and device for harmonic voltage emission levels. Background technique [0002] In recent years, the problem of harmonic pollution in power systems using large-capacity nonlinear equipment has received more and more attention. The voltage and current distortion caused by these devices in the power system will reduce the efficiency of power generation, transmission and power utilization, and will also interfere with relay protection and communication, resulting in disorder of each module of the power system. Power systems maintain planned levels of voltage harmonics by limiting the harmonic currents injected by nonlinear loads. [0003] Such as figure 1 As shown, how to provide a method that can quantitatively detect the harmonics of nonlinear loads at a physical point called the Point of Common Coupling (PCC) between the power sup...

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Problems solved by technology

Even if the power system allows this kind of interference to normal operation, it can also be found that this method is theoretically flawed by analyzing Equation 2: Equation 2 is based on the assumption that the background harmonics at the power supply end do not follow the power system due to the load at the user end However, since the background harmonics at the power supply end are actually determined by the parameters of the power supply network, the above assumption does not hold

However, to determine the impedance Z in an actual power system s and Z c It is very difficult, costly and time-consuming, so this non-intrusive method is still at the stage of theory, but not really applied in the field of engineering

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