Study On The Grid-connected Inverter Of Distributed Generation With Harmonic Inhibiting Function

With the development of energy saving and environment protection,the program about making use of new energy has been rapidly promoted in order to solve problems such as power shortage, environment pollution ,and so on. Distributed generation has been attracted by more and more countries in the world, and it will become an important power form in the future. Distributed generations in distribution network and substantial application of power electronic devices have resulted a decline in power quality, it has become an important problem that how to effectively improve the power quality while feedback gets to the grid in the distributed power generation system, the inverter has become a hot research. This paper mainly makes a detailed analysis and research on system topology, control strategy, parameter selection, and experiments in the net voltage and inverter.Firstly, according to the characteristics of distribution network with distributed generation, a new plan of governing harmonic wave has been proposed, that is to combine active power filter technology which can improve power quality with the distributed inverter power source, then to design a new type of multi-functional grid inverter. A small-signal mathematical model about grid-connected inverter has been set up by switch function method, the core of the composite control strategy is PI closed-loop regulation, voltage feed-forward compensation has been adapted to offset the impact of power grid voltage' disturbance on current ,then a better control can be abtained about the output current , the i_d-i_q harmonic current detection algorithm based on instantaneous reactive power can accurately detect and the separate the required active and harmonic component, phase-locked control algorithm based on DSP can make current and voltage have the same phase and frequency.What's more, sub-block design has been carried out on hardware and software of the grid inverter control system. Detailed analysis and description has been done in A/D conversion circuit, inverter drive circuit, PWM signal generation circuit of the inverter system. Human-Computer interaction function has been carried out by SCI asynchronous serial communication interface which is inside the master chip-TMS320LF2407A of DSP, Grid-machine communication function has been carride out by CAN control module, at the same time, flow cycle about main program of the control system and interrupt subroutine program will be given at the running environment of TI DSP2000. Additionally, Multi-function inverter power supply systems and related experimental auxiliary circuit of the three-phase PWM bridge inverter main circuit which consist of IPM in power device has been developed, experiments about active power's output of the inverter and the elimination of harmonic have been finished, the map of physical devices and experimental waveforms have been given, correctness of the inverter's working principle and feasibility of system design have been validated.The work of this paper done to broaden the ideas of distribution network of distributed power generation harmonic governance, and it has some strong theoretical and practical value for the promotion of energy-saving, power supply, the use of new energy and improving the quality of grid electricity.