Study On A Novel Active Filter To Cancel The Neutral Harmonic Current

Nowadays, the power supply bureau and customers pay more attention to the power quality. Harmonics contamination become more and more severe problems in power distribution system because of the ever-increasing nonlinear loads, such as converter, variable speed drivers, arc furnace, etc.Owing to the nonlinear loads, distortion of currents and voltages and so great third harmonics are caused and the power quality is terribly disturbed. This harmonic current flows through the neutral line to make a loop, which bring to great neutral harmonic current. Active power filter, an effective solution, have been widely researched and developed in the recent years.A novel active power filter for compensation of neutral harmonic current is proposed in this paper, based on the improvement of power quality. The topology, the method of detecting compensating components, the control strategy and design of physical circuit is fully analysized and detailly demonstrated in this paper. The content contains:Chapter two brings forward the configuration of main circuit and the principle of operation. Three main circuits are introduced: four phase converter, three phase converter, a novel instrument for compensating neutral harmonic current.Chapter three mostly discusses the detection of neutral harmonic current and control strategy in two ways. Two improved methods based on p-q , ip-i1 transform are firstly put forward. One is separated by zero-sequence power. The other is separated by zero-sequence current. Additionally, an adaptive detecting method based on the adaptive interference canceling theory. The control methods are briefly discussed including PWM hysteresis comparing mode and integrated learning Boost converter control. The application of integrated learning Boost convertercontrol to compensate neutral harmonic current is deduced in detail.In chapter four, a novel instrument for compensating neutral harmonic current is introduced in detail, such as main circuit, control circuit, etc. And some experiments are fulfilled. The results of experiment are given.