Abstract
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.
Highlights
Harmonic current flowing through line components is one of the main factors that cause adverse effects, such as increased losses and reduced operating efficiency
The fluctuation method is used to estimate the harmonic impedance based on the measured harmonic voltage and current information at the Point of Common Coupling (PCC)
According to the superposition theorem of the circuit, the PCC harmonic current Ipcc is the superposition of the harmonic current which contributed by the system side and the user side, as shown in formula (2)
Summary
Harmonic current flowing through line components (such as transformers) is one of the main factors that cause adverse effects, such as increased losses and reduced operating efficiency. Independent random vector covariance method is used to estimate the harmonic impedance by using the basic properties that harmonic voltage and current are independent approximation in the power grid and the covariance equals zero. It weakens the effect of background harmonics to a certain extent. Harmonic active power direction method was proposed on the base of harmonic state estimation It was widely used in the actual power grid because of simple and easy to use [2, 8, 16]. The results show that the proposed method is effective and accurate
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
