Application Research On The Hybrid Cascade Multilevel Inverter Of Chaos Theory In STATCOM

As an innovation technology in multilevel inverter，since the hybrid cascaded multilevelinverter can improve the quality of output waveform, reduce the voltage resistance ofswitching devices, save the transformers and greatly reduce the cost, it has been a hot topic inthe large-capacity research on STATCOM.In this paper the performance of chaos theory on the randomness，the topology ofcontagion and the density of point set of cycle in the phase space has been studied. In order toimprove the character of the single chaos sequence, a new chaos sequence based onChebyshev chaotic sequences and chaotic sequence with infinite collapse is built. Thesimulation results show that the new chaotic sequence has better random performance anditeration speed than single chaotic sequence. Through the character of chaos sequence and theprinciple of the RFPWM are analyzed, and a new modulation strategy based on RFPWM ofchaos sequence is presented. For improving operation performance of the hybrid cascadedmultilevel inverter and reducing electromagnetic noise and the harmonic, modulation strategyof RFPWM of chaos sequence is applied to the hybrid cascaded multilevel inverter. Thesimulation analysis is validated that the hybrid cascaded multilevel inverter based on the newchaos sequence can effectively reduce the overall harmonic amplitude, and reduce the noiseof inverter, as well as improve the switch device utilization rate and life of the inverter device.Being able to accurately detect the reactive and active current of system characteristics inreal time is the key of STATCOM steady operation. After the methods of p qand d qarecomparatively analyzed, the d qinstantaneous reactive power theory of testing technology ischose. Theoretical analysis indicates that reactive current can be fastly and accurately detectedby this method avoiding the influence of harmonic. The control method of states feedbackdecoupling based on RFPWM of hybrid chaotic sequence is presented, and applied to powergrid. The simulation results based on open loop and closed loop show that the above methodcan greatly reduce the harmonic amplitude, improve the performance of STATCOM, andeffectively ameliorate the response speed of STATCOM.