Research On Supply Current Direct Control Strategy Of ASVG

At end of the 20 th century, a lot of new power electronic devices had been developed, and the relevant technology is more and more perfect, at the same time, to promote the development of social stability and safety of power system operation, transmission capacity and the efficiency of power consumption, energy saving also had a bad influence, harmonic pollution, equipment of low power factor were severely reduces the grid power quality.Power grid in C hina is facing many challenges, such as transmission and distribution technology behind, low level of automation and fault cause blackout accidents.Therefore, urgent need for grid harmonic control and reactive power compensation tec hnology in-depth research, extensive research and development of application of new equipment, such as FACTS(Flexible AC Transmission Systems), the development of ASVG(Advanced Static Var Generator) has entered people’s field of vision, it is based on co nverter technique, equivalent to a controlled voltage/current source, by controlling the amplitude and phase of voltage/current source to control the size of the reactive power purposes.I t is now one of the active researching filed in power electronics course.This thesis based on the research on the distribution network dynamic reactive power compensation issue.Working principle and control method of ASVG analysis, combined with the traction power supply system balance problems do application verification.Research on ASVG control scheme, the existing ASVG current direct control and indirect control two basic control method, the two methods have their advantages and disadvantages, through comparative analysis in this thesis, the direct current control method.For direct current control method, this article first to the power supply current direct control compared with the traditional direct current control analysis, prove its consistency, namely adopt the power supply current direct control can achieve the traditional current direct control of the same control effect, because the method only needs to detect the power current, no need to load testing and calculation of reactive power and harmonic, makes the circuit is greatly simplified.Secondly, generate power supply current real-time tracking instruction value is the key to achieve power direct current control PWM signal, in this thesis, by comparing various tracking type PWM control technology, in-depth study of one-cycle control method, using one-cycle control method combined with direct control power supply current control of ASVG, and through the simulation analysis, prove the rationality of the control strategy effectively.Combined balance transformer and ASVG, the above method is applied to the co-phase traction power supply system, analyzed the basic working principle, from the main work of ASVG target analysis of the whole system works.Balance transformer, load and compensation system by the system of three parts, such as balance transformer is the main function of achieving a three-phase equilibrium, and a goal of eliminating harmonics and reactive power compensation. Output reactive current to compensate for the main function of ASVG load caused by reactive current and suppress the harmonic current. The design method of the main parameters is given.In this thesis, the ASVG had been in-depth analysis and research.Paper first introduces reactive power dynamic compensation principle; and through the analysis of the basic principle of ASVG, mathematical modeling. To establish the simulation model of balance converting device of power supply system, the simulation results and illustrate the co-phase traction power supply system of YN,vd balance traction transformer. The results show that the power supply of current is correct and feasible by using one-cycle control strategy.