DC Capacitor Voltage Control Strategy for the Cascaded STATCOM

ABSTRACT

In order to solve the DC capacitor voltage balance problem of the cascaded static synchronous compensator (STATCOM), a software method is presented. On the basis of overall control, a zero sequence injection method is used to realize the clustered balancing control. By using this method, a star-connected cascaded STATCOM will have a certain ability to compensate the unbalance load. An improved carrier disposition pulse width modulation method is proposed to realize the individual balancing control problem. By using the proposed PWM method, the charging and discharging time of the capacitors can be controlled by changing the distributive rule of modulation signal according to the capacitor voltages. The results of simulation and practical application show the validity of the proposed control strategy.

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