The Research Of Three-phase Four-wire Static Var Generator With One-cycle Control

With the development of the power electronic technology, the study of the dynamic reactive power compensation with Static Var Generator (SVG) has gradually become one of the more active research areas of the field of power electronics.In this paper, aiming at the complexity of the controller structure and difficult to be extended to industrial and engineering applications because of high costs of equipment, three-phase four-wire Static Var Generator (SVG) with one-cycle control is presented.The necessity of the reactive power compensation is first presented, then introduced and compared the existing reactive power compensation devices and analysis the advantages of SVG than any other devices; The main circuit structure of SVG and the control methods of indirect current control and direct current control are introduced. On the basis of comparison of two control methods, determined the indirect current control as a control method of this paper.Then discussed the basic operation principles and characteristics of one-cycle control in detail. As a nonlinear control method, it eliminates steady-state and transient errors by controlling the switching duty cycle in each switching cycle and control of the average variable reference signal equal to or into a certain proportion.Given the equivalent circuit of three-phase four-wire Static Var Generator (SVG) with one-cycle control and it's equation of the control objectives based on the analysis of its model cycle. One-cycle controlled three-phase four-wire SVG does not need detected three-phase load current and three-phase power supply voltage, no detection of harmonic and reactive current and no requirement of any multiplier. It's controller's composition is several integrator reset, flip-flops, comparators and a number of analog components. And it is easily extended to the practical application of industry and engineering because of the main circuit has constant switching frequency and the control circuit is simple, reliable, easy to implement.Next analysis the main circuit device and control circuit design of the one-cycle controlled three-phase four-wire Static Var Generator (SVG), introduced the device, analysis and choice of the circuit type and the calculation of the important parameters and the principles of the choice.Finally, do a wide range of load simulation using the MATLAB simulation software. Simulation results show that using the one-cycle controlled three-phase four-wire system SVG can reactive current compensation system effectively, and it has better compensation performance.