Key Techniques Of The High Voltage And Large Capacity Series Hybrid Active Power Filter

In the recent decades, with the repid development of the the power electronics technology, the widely industrial application of the nonlinear load based on power electronics devices has brought serious harmonic pollution to power grid, as well as a series of power quality problems. Meanwhile, various kinds of sensitive load demande stringent specification of power supply quality. In this context, the harmonis problem became serious. The hybrid active power filter now is the research hotspot in the harmonic suppression, since it has both the advantages of the passive power filter and active power filter, such as low cost, high reliability and flexible compensation and so on. The object of study of this dissertation is the new type series hybrid active power filter (SHAPF) based on fundamental magnetic flux compensation (FMFC). Some related problems are discussed.This dissertation introduces the three-phase SHAPF based on FMFC. Then discuss the disturbance voltage coupling problem in different phase when adopt six bridges inverters. The theoretical analysis account for the reasons the filtering effects adopt three-phase inverter is less then the three number of single-phase inverter. Adding midcourt line can uncouple the disturbance voltage and improve the filtering effects. The validity of the theoretical analysis conclusions is verified by the experimental results.In order to solve the DC voltage control problem of the series hybrid active power filter, a novel DC voltage control strategy of the SHAPF is proposed. This new control strategy is independent of the detection of the primary winding port voltage of the series transformer. The inverter generates fixed active power current, so that the fundamental voltage loss of the series transformer may remain stable. The controlled DC voltage provides the feasibility of the SHAPF based on FMFC to adapt various working conditions. This DC voltage control strategy has no additional power electronics device, and not increase the cost.When adding the same phase harmonic current instructions in current control block, the system current of the SHAPF appear oscillation phenomenon. The essence of oscillations phenomenon is that the SHAPF system is unstable to the interharmonics current. In order to solve this problem, some methods are proposed. From the practical viewpoint, the voltage feed-forward control is easy to achieve. It can reduce the current oscillation problems, and also improve the filtering effect. The feasibility of these methods is validated by both the emulation and experiment results.Taking the series hybrid active power filter based on magnetic flux compensation as example, this paper analyzes the interharmonics stability of the APF systemThe conclusion of the above research is that when the SHAPF based on FMFC applied in the high voltage and large capacity electrical power system, it is suitable to choose three single phase H bridge inverter instesd of three-phase inverter. And the same phase harmonic compensate current is unnecessary. Then based on these conclusions, the equivalent harmonic impedance model of the series is established. And on the basis of the model, the impact of the parameters of the series transformer to the equivalent harmonic impedance is discissed. The conclusion is that the turn’s ratio k of the series transformer has greatly imfluence to the filtering effects. Then takes the10V,0.8MVA electrical power load in a certain factory in Guangdong Province as example, the accurate global mathematical model of the SHAPF based on FMFC is established. The series transformer parameters and the inverter control parameters are discussed in detail to show its imfluence to the filtering effects. This accurate global mathematical model can be used as foundations of the parameter selection of the SHAPF. The simulation results verify the validity of the theoretical analysis.On the basis of the above work, an engineering prototype has been manufactured and well running in the factory in Guangdong Province. A good filtering performance is achieved. This dissertation also pays attention to the some related problem, such as the tilerting effect in some extreme working conditions, and the load voltage.