Research On Control System Of Cascade Multilevel STATCOM

As one of core equipments of flexible AC transmission system, Static Synchronous Compensator (STATCOM) plays an important role in reactive power compensation, maintaining power grid voltage, improving steady and dynamic performance of system. It is power electronics equipment with superior performance.This paper chosen cascade multilevel STATCOM as research object by comparing STATCOM with different circuit structures. In order to improve the response speed and control precision of STATCOM,this paper adopted direct current control method based on d-q axis. About the prominent problem of imbalance of units voltage in DC side, this paper studied voltage balance control based on active power overlying with the combination of hardware and software, which improved the reliability of balance control. Adopted quick detecting method based on instantaneous reactive power theory to detect system reactive power. Considering the structure characteristic of cascade multilevel STATCOM, applied phase shift pulse width modulation in half period, which could increase equivalent switching frequency to gain better harmonics characteristic.This paper designed hardware circuit and control program according to the demand of modularization and production. In addition, considering the integrality of system research, introduced the design of monitoring system of STATCOM equipment, including system hardware, software design and communication.Adopted MATLAB/SIMULINK to establish simulation model of control system of cascade multilevel STATCOM to prove control method and comprehensive performance. Established experiment platform of STATCOM equipment to test its running performance, which proved the feasibility and superiority of control method.