Research On Control Technology Of Active Power Filter

With the development of power electronics technology, application of non-line devices is more and more widespread as well as lots of harmonics are injected to power system. Many problems are caused by harmonic pollution, such as lower power factor and bigger wastage; even power system will be paralytic. In order to solve the above problems, the most effective strategy of improving and governing electric quality is adopts the APF that can compensated harmonic dynamic. However, APF still exist some deficiencies which are limited capability, inaccurate harmonic currents and lower compensated effects dynamicly. Thus, the subject investigated is harmonic compensation of APF technology.Base on APF operating principle, a novel parallel HAPF is proposed in this paper against limited capability , which key technologies are detection of harmonics and reactive currents as well as the control of compensated currents. A lot of methods for three-phase unbalance power system harmonics current detecting have been proposed to improve the performance of active power filter. To avoid some shortages which exist in the harmonic current detecting methods now, an improved ip-iq algorithm based on instantaneous reactive power theory is presented.Under the balanced power system ,this method is through the establishment of new mathematical models and algorithms can real time and accurate reference the harmonic current effectively at the same time to facilitate the project only on the active filter harmonic current compensation. In unbalanced power system, the balance to be bound by the grid design of APF will not be running normal. Ac will have a negative sequence current, so severe asymmetric current network side.The thesis gives out a new three-dimension complex space power definition based on the synchronous rotating coordinate is suitable for APF control and the power analysis of the unbalanced case. At the same time, on this basis it was proposed that AC suppression of negative sequence current control strategy. The strategy allows the system to improve the active power filter current response speed, lower power loss, is an optimal space voltage vector control program.Ultimately, the APF system is simulated by Matlab/Simulink and part circuits are designed. The simulation and test results verified that the proposed system improved current dynamic and harmonic suppression capability. So the research of APF in this paper has a great asset to APF technology.