摘要：It is difficult to determine the harmonic current which flows through the line element in power grid, the paper proposed a new method for identifying the main harmonic current indicator at the Point of Common Coupling (PCC) based on the strict mathematic constraints. At the fundamental of the harmonic Norton equivalent circuit, the paper analysed that the harmonic active power direction method can be completely correct and valid in a certain interval. Combined the basic principles of the circuit and the strict inequality constraints, the paper discussed various fundamental characteristic of the harmonic impedance on both the system side and the user side, with the harmonic voltage and current measured amplitude and phase angle at the PCC. When the indicator of main harmonic current is the user side, the method can directly get the conclusion with the phase angle difference between harmonic voltage and current. When the indicator of main harmonic current is the system side, the method can get the conclusion combined the phase angle difference between harmonic voltage and current and harmonic impedance. Finally, the paper used the measured data of a variety of practical engineering scenarios to verify the correctness and effectiveness of the method.
