The Study On The Control Strategy Of Reactive Power Compensation And DC Ice Melting Of Static Var Compensator

In recent years,various types of extreme weather in the world have occurred frequently.The loss caused by ice and snow disasters to the power grid has become more and more serious,and the degree of damage has become more and more serious.It is also more difficult to restore the power grid after the disaster.Overhead line icing in areas where extreme cold and freezing weather occurs frequently leads to serious losses of power grid,such as conductor galloping,ice flashing,broken lines and inverted towers.Frequent occurrence of ice and snow natural disasters makes the power grid in these areas equipped with DC ice melting devices.At present,the majority of DC ice melting devices use thyristor rectifier control technology,which will consume a large amount of reactive power and produce a certain amount of harmonics,which has a negative impact on the AC network.The modular static var synchronous compensator and DC ice melting device based on full bridge sub-module has the characteristics of less harmonic content,convenient operation and high power quality,so it has gradually become a hot spot in the field of grid ice melting research.The static var synchronous compensator and DC ice melting control strategy will be studied in this paper.Firstly,the operation topology and working principle of the reactive power compensation of the static var synchronous compensator are introduced,and the mathematical model of the reactive power compensation process is given.Then,the reactive current detection method based on the instantaneous reactive power theory and the PI control method of the DC side and the AC side of the static var synchronous compensator are analyzed.After that,the operation topology and working principle of the static var synchronous compensator DC ice melting are introduced,the mathematical model of the DC ice melting process is given,and the capacitor voltage balance modulation method and DC ice melting control method of the sub-module of the static var synchronous compensator are analyzed.Firstly,the function parameters of DC ice-melting are determined,then the basic parameters of DC ice-melting mode and reactive power compensation mode of static var synchronous compensator are analyzed.Finally,the design parameters of static var synchronous compensator are determined,and the control system of static var synchronous compensator is designed.Finally,a simulation model is built on the MATLAB/Simulink simulation platform to verify the reactive power compensation and DC ice melting control method of the static var synchronous compensator.The simulation results show that the static var synchronous compensator has a good compensation effect on the power grid,and it can also continuously adjust the DC voltage from zero to set value,with different lengths,different voltage levels and different types of overhead lines ice melting.This validates the dynamic reactive power compensation and DC ice melting capability of the static var synchronous compensator effectively.