Research On STATCOM In Low Voltage Unbalanced Power Grid

With the acceleration of the industrialization process,the use of various large-capacity electricity load(such as electric arc furnace,electrified railway,etc.)in the power grid causes the load distribution among the three phases to be extremely uneven,making the environment of the power grid deteriorate and seriously threaten the power grid Safe and normal operation of electrical equipment.(STATCOM)as a new compensation device,with the suppression of harmonics,compensation for reactive power and reduce the balance of a variety of functions,can effectively purify the grid environment.In this paper,STATCOM is designed and developed for the compensation of unbalanced load in three-phase four-wire system.This paper first introduces the harm caused by unbalanced load and its suppression method and the development direction of unbalanced compensation device.Then the basic working principle of STATCOM is selected,the appropriate topology is selected,and the corresponding mathematical model is established based on the structure.After that,the compensation current detection scheme and voltage and current control strategy of STATCOM are studied.In order to improve the tracking accuracy of the compensation current,the triangular wave comparison control method using the regular sampling method is adopted.Then,the analysis and design of DC side voltage control are carried out from two aspects of voltage stabilization and voltage sharing.Finally,the Matlab simulation is carried out according to the adopted scheme.The result shows that the design is reasonable and correct,and then an experimental prototype is designed and debugged.The experimental results show that the STATCOM design has a good compensation effect on the three-phase unbalanced load.