Research On Control Of The Stable Of DC Bus Based On The Power Electronic Converter Cascade

With the development of power electronic technology, the tradition centralized power plant can not be suit for the development and transmission of the renewable energy source,besides, more and more DC loads have been used, and then the DC distributed power system is rised in response to the proper time and condition. As the DC distributed power system is composed of many power electronic converters, so the interaction between them,have a huge impact on the entire DC distributed power system, especially in steady-state and dynamic performance. Therefore power electronic converters stability of interaction is one of the key technologies of DC distributed power systems. This paper is a study for a two-stage cascade stability control DC distributed power systems:First, the impedance ratio of the criterion based on the DC power electronic converter cascade distributed power system is analyzed, and Buck converter for non-ideal small signal model which is often used as the source of the converter and the load converter is built. Its single closed loop PI control output voltage input impedance is derived, and the factors that may affect the input impedance of the output are analyzed. It is often used as a load for a three-phase PWM inverter converter small- signal modeling, derives its single closed loop PI control voltage input impedance. A single closed loop PI control voltage Buck converter and single-phase voltage closed-loop PI control PWM inverter input impedance which have a negative impedance characteristic low frequency similar to the constant power load is analysed.Secondly, this paper introduces a DC bus regulator, which can compensate harmonics and reactive current on the DC bus and stable power supply due to the mismatch cascade impedance DC power electronic converters in distributed power systems caused by the DC bus voltage oscillation. Analysis of the DC bus regulator principle, and its structure is analyzed, the design parameters of the main components and control strategies. Combining the simulation results, the DC bus regulation gradually is elaborated functions.Finally, according to double-loop control strategy, a DC bus regulator experimental platform is built, where the system controller chip using ST’s STM32F103ZE, hardware circuit debugging with ARM on this paper, and the DC bus regulator experimentally is verified. Experimental results show that the DC bus regulator in the case due to the secondary cascade closed-loop system closed-loop input impedance and output impedance mismatch,causing the DC bus voltage oscillation to stabilize the DC bus voltage. At the same time when the load converters, that is a single-phase voltage closed-loop PI control PWM inverter with unbalanced load caused by the DC bus voltage drops and vibration, DC bus regulator has good inhibition. The feasibility and effectiveness of the DC bus regulator proposed in this paper is vertified.