Analysis and Simulation of Cascade STATCOM Based on PAM Inverter

In order to achieve similar harmonic elimination effect as Pulse Width Modulation (PWM) method at a lower switching frequency and solve the problem of DC capacitor voltage unbalance, the Pulse Amplitude Modulation (PAM) method and the method of pulse exchanging circularly are proposed in this chapter. By solving the optimal objective function, the angles of switching point can be worked out. It makes the low harmonic performance and the total output voltage optimal. The pulse generators rotate each fundamental frequency cycle time in the pulse distribution, and 10 fundamental cycles (200 ms) are needed to complete one cycle pulse rotation mechanism, which effectively improves the condition of the capacitor voltage difference. Then a neural network PI controller is designed to tune the parameters of the PI controller timely. The results of simulation show the correctness of the proposed method. It can adjust the changes through the simulation.