The Study Of Micro-source Inverter With The Function Of Harmonic Compensation In AC Microgrid

In recent years, many micro-source and power electronic devices are applied into the micro-grid. The intermittent characteristics of micro-source and extensive use of power electronic devices will bring voltage fluctuations, frequency change, harmonic and other power quality problems. Among them, harmonic problem will have a negative impact, such as increasing the system loss, affecting the normal work of other equipment and so on. So the harmonic problem of the micro-grid has been studied by many scholars. For solving the harmonic problem, the micro-source inverter with the function of harmonic compensation is mainly studied in this thesis.Firstly, the structure and control principle of three-phase voltage micro-source inverter and parallel active power filter are compared and analyzed, and the topology structure and control theory of the micro-source inverter with the function of harmonic compensation is given. The micro-source inverter has two functions, one is injecting power to micro-grid, the other is compensating harmonic current. At the same time, a storage device is added the DC link of the micro-source inverter to maintain the balance of input and output power of micro-source inverter.Secondly, the deadbeat control, which is based on the mathematical model of the controlled object and has good dynamic performance, is applied into the control of the micro-source inverter with the function of harmonic compensation. And hybrid prediction method, which combines the repeated prediction method and the Lagrange extrapolation, is used to improve the traditional deadbeat control for solving the delay problem of the traditional deadbeat control. And the improved deadbeat control method is simulated by Matlab/simulink.Finally, from the micro-grid level, the coordinated control of multiple micro-source inverters is the focus of research when the micro-grid contains multiple micro-source inverters. Make sure that each micro-source inverter finished inject power to micro-grid, harmonic compensation ratio of each micro-source inverter is allocated according to the remaining capacity of each micro-source inverter. The coordinated control of multiple micro-source inverters can solve the problem that single micro-source inverter is limited by capacity. And the coordinated control of multiple micro-source inverters is verified by Matlab /simulink.