Photovoltaic Grid-Connected Inverter Harmonic Compensation and Grid-Connected Unified Control

On the basis of the research on grid-connected technology of distributed generation system, in order to extend the full advantage of single-phase photovoltaic grid-connected energy and gain rapid electric energy conversion and high quality electric energy and achieve accurate control and reactive power and harmonic compensation, a control scheme of grid-connected in conjunction with harmonics presented. Based on instantaneous reactive power theory, algorithms of current decoupling in the single-phase system are derived for performing the reactive power control of single-phase photovoltaic grid-connected inverter. The method proposed effectively solves the difficulties of the current detection in single-phase connection. The paper derives the algorithm and duty factor of pulse width modulation (PWM) and duty factor of grid-connected inverter. With this system used in the two grade single-phase photovoltaic grid-connected inverter, instantaneous harmonic and reactive current will be compensated and photovoltaic grid-connected system has the energy that take advantage of solar module rapidly. Power quality will be improved and the practicability of photovoltaic grid-connected system will also be enhanced. On the basis of analysis , a experiment prototype was excogitated. IN conclusion, not only the system has the function of supplying active power, but also can perform reactive power and harmonic compensation .It will be of great reliability and dynamic performance in the near future and the algorithm is very simple and easy to achieve.