Research On SVG And Its Influence On Voltage Stability Of Power System

With industrial development and social progress,electricity load increase and a large-scale power systems is formed gradually.Voltage stability of power system is not just a power issue and is also vital issue related to the safe operation of large power grid,so more and more scholars begin to devote themselves to the study of system voltage stability.The voltage level of the system is the embody of co-ordination of supply and demand of reactive power of power system.Reactive power losses will directly affect the voltage drop in the process of capacity transmission.With the development of technology,SVG become the most advanced reactive power compensation device at present in that in-depth study of the impact that SVG has on voltage stability of power system is of great theoretical and practical significance.This report mainly includes the following aspects:1.This text uses an algorithm of reactive power optimization to determine the compensation capacity of the power system and adopts the niche genetic algorithm by the comparison of several commonly used reactive power optimization algorithm at present.It introduced mathematical model and workflow of the algorithm at first,then use it to determine the reactive power capacity of the standard system adopted in the text,which is the capacity of reactive power compensation devices.2.On the basis of above work,I designed a multi-level linking SVG after determining system capacity and type comparison of reactive power optimization,Its main circuit adopted the six H-bridge connected topology of multi-level inverter;three-phase current resonance integral control is used as the control strategy.PR controller can coordinate power current floating in a rest frame and don’t need the dq coordinated] transformation and positive and negative sequence decomposition, thus reducing the dq transform part in current detect;make it more convenient to control SVG and save time of reactive power compensation action.3.By determination of reactive power optimization to system capacity and SVG designed in this report,we put them into the selected system to study effects of SVG on voltage stability.The text choose two standard system to analyze and they are three machine nine node system and IEEE33 node system.Analyze the impact the SVG has on voltage stability by simulation and obtain and verify that SVG improve voltage stability and its value of power system.