Research And Application Of STATCOM Technology Used For Suppression Of Sub-synchronous Oscillation

With the development of economy human society, thepopularity of electric equipment and electrical automation made the power grid morecomplex, therefore,the power quality is requested to be better and better, concepts ofpower factor, harmonic distortion rate and electrical damping show attention topower quality from people.With the development of computer technology andconverter technology, many compensators have been a large number of applications,in the direction of high pressure dynamic compensation, cascade STATCOM hasbecome the hot topics in the study of the current converter.Based on the comparison of some typical STATCOM topology, the cascadeSTATCOM as the main research object is determined. On the study of PWM, thispaper is deduced method which modulation wave transform in order to improve theutilization rate of dc voltage in the Angle of special solution and general solution ofthe control equation, proposes the thinking which improve method ofPWM-controlling. Through the study of a variety of phase-locked loop method, thispaper proposes a feed forward phase-locked method based on SOGI, solved thephase-locked loop in the complex system that frequency and amplitude changed.Through the ip-iq and p-q test contrast, proposed a modified method of the ip-iq,the method can extract fundamental wave signal from the harmonic source andunbalanced three-phase. Several key parts Control strategy of STATCOM isintroduced: current loop control, voltage loop control,three-phase imbalance controlbased on positive and negative sequence decoupling, according to the research of thechange of dc side capacitor voltage, put forward a kind of control strategy based onsuperposition of double voltage loop, solve the problem of the dc side voltageimbalance. Finally, in the MATLAB building a7level star connection model ofSTATCOM, verify the correctness of the stated theory by simulation.Suppress Sub-synchronous Oscillations,and determined the STATCOM cansuppress sub-synchronous oscillation and control method of multiple modalseparation, and gives the design method of modal filter. according to the discussionsmentioned above,put forward control strategy of suppression of sub-synchronousoscillation of STATCOM, and according to the PI control can’t tracking AC signal,put forward modified control strategy of suppression of sub-synchronous oscillation.finally,the simulation compared the two control methods, verified control effect ofmodified control strategy.According to the study of cascade STATCOM, analysis of sub-synchronousoscillation mechanism and aiming to problems of sub-synchronous oscillation of HuMeng grid system, designed a set of20Mvar/10kv star the cascade STATCOMdevice is used to suppress sub-synchronous oscillation, building Hu Meng system model in the RTDS lab, verified the effectiveness of the STATCOM used to suppresssub-synchronous oscillation. According to the different working conditions, differentdisturbances and different control parameters,doing a lot of experiments proved thatthe STATCOM used to suppress sub-synchronous is correct and feasible theory, andhave achieved good results under a variety of working conditions.