Voltage Stabilization of VSI SMES Capacitors and Voltage Sag Compensation by SMES Using Novel and Optimized Switching Strategies

This paper presents a novel and optimized switching strategy and control approach for a three-level two-quadrant chopper in a threelevel Neutral point clamped (NPC) voltage source inverter (VSI) superconducting magnetic energy storage (SMES). Using the proposed switching strategy, the voltage of the inverter capacitors in SMES can be independently controlled. Also, the minimum power and switching losses as well as the proper convection can be achieved using this switching strategy. The simulation results indicate that the proposed switching strategy along with a proportional-integral (PI) control approach can be easily implemented in the power networks, and it can balance and stabilize the capacitors’ voltage level of the multi level inverters while satisfying the IEEE standard specifications. To investigate the effectiveness and reliability of the proposed approach in stabilizing the capacitors’ voltage, the performance of SMES using the presented approach is compared with that of SMES when the capacitors of the three-level inverter are replaced with equal and ideal voltage sources. This comparison is carried out from the power quality point of view and is shown that the proposed switching strategy with a PI controller is highly reliable. Considering the fact that the Space Vector Pulse Width Modulation (SVPWM) is highly effective in decreasing the low order harmonics, in this article, this type of modulation combined with the most optimized switching strategy is utilized. In addition, in this study, a new algorithm is presented for SMES to compensate the voltage sag in the power networks. Simulation results show that the VSI SMES combined with the proposed algorithm is able to compensate the voltage sag and phase voltage in less than one cycle.

کلیدواژه ها:

Voltage stabilization ، voltage sag compensation ، optimized switching strategy ، threelevel Neutral point clamped voltage source inverter ، two-quadrant three-level chopper