The Research On Single-phase Harmonic Suppression Transformer And Its Supporting Active And Passive Hybrid Filter

With wide use of the electronic equipment and industrial and civilian electricity load rapid increased, a great amount of harmonic currents injected into the power system, then caused the power quality decline, loss increased and efficiency of system depressed, the security and stability of power system operation is seriously affected. These harmonics act on the transformer cause additional harmonics losses of transformer, lead transformer additional temperature rise and its useage lifetime decreased. So the research of harmonic suppression of transformers and its filter devices is of great significance.The concept of harmonic and its occurring reasons and hazards is noted, the harmonic damage to transformers pointed out in particularly; the basic structure and fliter principle of passive filters and active power filter are described; and a variety of the hybrid filters structure are introduced.Some different harmonic detecting methods are analysed, and their limitations in application are pointed out. The theory of instaneous reactive power and its using in the single-phase detection circuit is described. Then, an improved detection method based on the theory of instaneous reactive is introduced, and a harmonic current detection method based on the theory of phase distinguishing is recommended and simulation is implemented to demonstrate the superiority of this detection method. Several commonly used controlling methods of active power filter are comparative analysed, and choosed one-cycle control method that response fast and the structure of control circuit simple as resrarch key target. In order to solve the disadvantages of one-cycle controlled APF, a new control method of APF combined current detecting method based on phase-distinguishing theory and one-cycle control is proposed, it can be Flexible to choose targets compensation, and simulation of this program is implemented.The general concept and topological structure of single-phase harmonic suppressed transformers are introduced, this transformer using their own magnetic potential balance principle to suppress harmonic. Various harmonic-suppressed transformer structures relatives to passive filters, active filters and hybrid filters are given, and the technical features of single-phase harmonic-suppressed transformers are described. Finally, the filtering method of single-phase harmonic-suppressed transformer is presented, the main parameters of filtering decives of harmonic-suppressed transformer are offered, and the simulation of inductive harmonic-suppressed transformers and auto-coupling harmonic-suppressed transformers are implemented, the results of simulation show that: the filtering effect of this harmonic-suppressed is good, and performance is superior to conventional filtering methods, thus provides theoretical foundation for the following reseaches.