Novel Control Strategy Of Unified Power Quality Controller Upqc Direct Control Methods Of The Theory And Realization

As the main energy of the modern society, electrical power is applied in all walks of life. And electrical power quality involves the total result of national economy. The unified conditioning technology of power quality, based on power electronic technology, is one of all important branches of Custom Power. UPQC (Unified Power Quality Controller) is one of the most up-to-date development trends of Custom Power, which combines the functions of voltage compensator, current compensator and energy storage device and must have a prospective future. Multiple power quality regulation functions are implemented in UPQC simultaneously. UPQC is a more effective way to regulate the power quality of distribution system systematically and improve the reliability of power supply than others. Therefore, UPQC is becoming an emphasis of related research.Based on practice of improvement of power quality, this paper first of all analyses in detail the main circuit topologies and control technologies of Unified Power Quality Controller and deals with deeply the theory, topology, compensation strategy and control strategy for loop system of UPQC. Also the comparing between the advantage and disadvantage of its main control modes and strategies existing at present and the analyzing of their future are provided. In the way of direct compensation, the precision and the real-time of calculation of the aberrance will influence the whole compensation effect of UPQC. But in the way of direct control, there are no need to detect or calculate the fluctuation and harmonic of power line voltage, and reactive power and harmonic current of loads. Because of its brief circuit, easy achievement and good real-time compensation, the direct control mode is considered to be a more promising control method. Through the exhaustive discussion above, a good control scheme is selected and this paper will focus on the theory and realization of single-phase UPQC with basic topology which uses novel control strategy and direct control mode.Studying in the power supply current-direct control method and its equivalence of active power filter, the rationalization and feasibility of UPQC's novel control strategy is proved. In the third chapter and the fourth chapter, the unified model of the whole single-phase UPQC system is build according to its dynamic physical performance. Both the series part and shunt part of UPQC are designed as voltage-current double-closed loop control models. This paper uses the design principles of typical 2 order control system to design these two control models, involving computing the parameters of power circuit, filter circuit, reference signal producing circuit, control circuit and so on. Then all parameters are optimized using ideal Psim Simulation and real ICAP/4 Simulation to obtain better compensation results. On the foundation of simulation model, the simulation results obtained verify that the control algorithms are feasible and rational and can be applied in practice. Besides, this paper also discusses the basic elements of Hysteretic Current Control method with constant frequency, and then designs the control adjustor and Simulates the circuit.On the basis of above researches, every unit hardware structure of single-phase UPQC is designed, chosen and experimented. These unit circuits conclude the selection of power switching device, the realization of a certain functional module, the choice of control chips and isolation circuits and the computations of filter capacitors and inductances which play an important role for UPQC's dynamic performance. Also the experimental results are provided and analyzed. Lastly a unified power quality conditioner is designed and implemented.In one word, this paper gives the reference of novel direct control strategy in UPQC, and will improve the development and application of the UPQC.