STATCOM Research Cascade Multi-level Technology

With the rapid development of the social industrialization, as well as thecontinuous improvement of living standards, the security and stability of powersystem directly affects the development of the country. Non-linear load reactivepower consumption of the grid has become a great hidden danger, so reactivepower compensation becomes the key research objectives of the world. StaticSynchronous Compensator (STATCOM) as the application of power electronicsresearch and development of new type of reactive power compensation device,which can realize the dynamic continuous compensation, fast response speed,good control precision and good performance to make it become a hotspot of thefield of reactive compensation.Firstly, the background of developments in the field of reactive powercompensation is introduced, on the basis of the analysis several typicalSTATCOM main circuit structure analysis, and the cascade multilevel structureis selected as the main circuit structure. Then mathematical model is establishedand the stability of the STATCOM system is analyzed. In the respect of themodulation strategy, the carrier phase shift modulation method is adopted.Simulation results show that the feasibility of the main circuit.Secondly, in the aspect of reactive current detection, the current detectionmethod based on instantaneous reactive power theory is chosen, and theimprovedi p iqreactive current detection method is proposed, it is able todetect the reactive current fast and accurately when three-phase voltages areasymmetrical. Simulation results demonstrate the rationality of detectionmethodsThirdly, the current indirect control method is chosen on the basis of theanalysis and comparison of STATCOM control methods. And in view of theproblem of the voltage unbalance of the dc-link capacitor, the method thatconsumes a small amount of active power of the system is proposed. Thesimulation results show that the effectiveness of the method. Finally, the whole simulation model of the STATCOM is built andsimulated for different load conditions. Simulation results show that the dynamiccompensation effect is good and fast.