Research And Design About Static Synchronous Compensator Based On Asymmetrical 3H Multilevel Inverter

With the development of multi-level technology, the STATCOM containing multi-level inverter shows its superiority, attracts more and more attention. Asymmetric multi-level topological features of more level output with fewer devices, has been placed in the application research on STATCOM, this is of great significance.In this paper, the asymmetric 3H multi-level inverter is proposed as the main circuit topology of STATCOM. The operation principal and control methed of asymmetric 3H inverter have been analyzed. A Static var compensator which contains asymmetric 3H inverter as the main circuit topology has been designed.In theory part, the operation principal of the STATCOM has been analyzed. Indirect current control method and single-phase instantaneous reactive current detection method have been studied. The operation principal of asymmetric inverter has been analyzed, and the asymmetric 3H inverter has been deeply analyzed, and carrier wave disposition method of part PWM on asymmetric 3H inverter has been deeply analyzed and improved.The simulation software Simplorer is used to simulate the STATCOM based on the asymmetric 3H multi-level inverter, the simulation results show that the STATCOM based on the asymmetric 3H multi-level inverter has a good output voltage waveform and it can achieve better effect of reactive power compensation.The hardware and software of the STATCOM based on the asymmetric 3H multi-level inverter have been designed. Main circuit, detection circuit, control circuit, PWM generation circuit and driver circuit have been designed as hardware. Control circuit uses two ARM7 embeded chips, which communicate with the dual-port RAM. A/D sampling program, reactive current calculation program, communication program, digital PI program and modulation wave control signal program have been designed as software.Basing on the design of the hardware and software, an experiment prototype of the single-phase STATCOM based on the asymmetric 3H multi-level inverter has been made. Reactive power compensation experiments have been done in the case of inductive load, capacitive load and load mutated. The experiment results show that the experiment prototype of the STATCOM have a good compensation effect in different operating conditions. The quality of the output waveform reflects the advantage of multi-level.