Research And Application About STATCOM Based On Improved Asymmetric Cascaded Multilevel Technology

A new hybrid cascade topology is studied based on the transformation of2H bridge after analyzing the common multilevel topologies and call it2H/5-H in the paper. The5-H bridge uses only five switching devices producing five-level voltage output, the new cascade topology uses only nine switching devices but can produce nine-level voltage output, and applying it to STATCOM.In theory part, analyze the basic principles and PWM control methods of STATCOM, focus on a reactive current detection method based on single-phase system. Reduce the number of triangular carrier to simplify the hardware design based on stacked PWM control method.The simulation software Matlab is used to simulate the principle and reactive power compensation ability of the topology, the results show that no matter in inductive, capacitive or dynamic process, STATCOM has good reactive compensation effect.Hardware and software is designed based on hybrid cascade topology, hardware design mainly includes:main circuit design, control circuit design, and dead zone protection circuit design. Software design includes data acquisition program design and main control program design.After completing the above designs, a single-phase hybrid cascade inverter is designed. First, verify the feasibly of the topology, and then experiments are done on low power factor and high power factor. Results show that both the quality of the output waveforms and the results of reactive power compensation are satisfactory.