The Design Of Grid Connected Inverter Based On DSP With Active Harmonic Suppression

Fossil energy using brings two aspects problem to humans: on the one hand, the use of a large number of fossil fuels leads to the depletion of non-renewable energy; on the other hand, an environmental problem caused by the burning of fossil fuels is constantly increasing. Distributed power generation technology could develop and use the green pollution-free energy such as wind power and solar energy to replace the traditional fossil energy, so it makes the technology become one of the hot research topics in the world today. The energy exchange between distributed generation system and power grid is by inverter circuit implementation. Therefore, grid inverter directly affects the quality of the grid electricity, its specific performance in reliability, conversion rate and harmonic content; it is the key that the distributed generation system performance is good or bad. In addition, due to the power grid presents large amounts of power electronic and nonlinear devices, it injected a large amount of harmonic into the power grid causing pollution of grid environment. Therefore, how to control the grid inverter makes its safety grid at the same time and improve the quality of grid electricity, these become one of the most important research hot spots.The essay is based on the three-phase grid inverter as the research object, according to power grid harmonic interference problem, it realized to implement harmonic suppression on the premise of the traditional grid inverter, namely it joined the synthetic virtual the harmonic impedance link in conventional current and voltage closed loop control, in order to realize to reduce the harmonic in the grid and to achieve national grid requirements in. effective interconnection conditions. The essay is based on three-phase power grid as an example, this paper firstly introduces the basic principle of three-phase grid inverter, then focuses on the closed-loop control method of harmonic suppression in voltage. It increases in the voltage loop variable virtual harmonic impedance to reduce the transmission lines to produce resonance and meet the requirements of grid. Under the condition of the above ideas, in this paper, it gives two control methods based on the specified frequency synthesis harmonic impedance and harmonic impedance based on second-order generalized integrator synthesis. In MATLAB/SIMULINK simulation platform, this paper sets up a system simulation model; the specific process includes extraction of the harmonic wave in the power grid, synthetic virtual harmonic impedance, and voltage current closed loop control circuit, generating SPWM inverter control work to achieve interconnection. In addition, this paper analyses and designs the hardware experiment system, which mainly includes the control system of main circuit, drive circuit and analog signal sampling circuit, etc.The experimental results show that increase of harmonic impedance of the double closed loop control method in this paper can effectively reduce the harmonics of power grid and improve power grid power quality, this paper is proved the feasibility and effectiveness of the designed control scheme and realize the purpose of this article design.