Modeling And Performance Analysis Of Renewable Sources Power Generation Buck-Type Voltage Source Converter

In order to meet the power demands, countries around the world focused on the generation power technology of clean renewable resources. So the research on grid-connected inverters is very important. With the development of fully controlled devices and the improvement of their performance, the application of voltage source converters became more and more common. The dissertation [26] presented a novel Buck-type voltage source converter (BVSC) and a novel dual-frequency Buck-type voltage source converter (DBVSC). Comparing with the conventional converters, the BVSC can achieve excellent output waveforms, and the DBVSC can reduce switching loss and improve power grade, which is suitable for large power situation.This dissertation mainly focused on modeling one-cycle controlled BVSC and DBVSC, and analyzing their steady-state performance and dynamic-state performance. The achievements of the dissertation are as follows:1) Summarize the modeling methods of switching converters, and adopting state-averaging method to build the model of the system. Analyzing the working situation in different switching states, deducing the expression function of main voltage and current, and building the linearized averaging model of the BVSC. On this basis, the steady-state function, the small-signal model and its equivalent circuits were achieved;2) Making small-signal perturbation analysis to the BVSC control function, and obtaining the model of the whole system. Deducing the input current-output current open-loop transfer function and the input voltage-output current open-loop transfer function of the whole system, drawing bode plots and analyzing the faults. Then designing the compensating circuit, and comparing the compensated system performance with uncompensated system. Calculating the close-loop transfer function of the system, and analyzing the dynamic performance by simulation both in time domain and frequency domain;3) Analyzing the equivalent circuit of DBVSC in different switching states, and deducing the small-signal function and equivalent circuit. Applying the same method to compensate the system. Simulating the DBVSC system with perturbation and the results confirmed the theoretical analysis.