The maximum power point tracking technology（MPPT）

as an important control strategy of PV grid system

is the key to keep system fast dynamic response and improve power quality of distribution network. In this paper

several kinds of common MPPT algorithm are analyzed and a kind of algorithm for the improvement of particle swarm is proposed. The algorithm ensures that the optimal solution can be based on the current moment of the global optimal solution for sorting

updating so to improve the tracking speed and accuracy by way of limiting the speed of particle with self-adaption. Finally

the influence of the algorithm on power quality is analyzed quantitatively in accordance with such parameters of the three kinds of algorithm as outpour power

voltage of the grid-connection point and harmonic contents of current etc. It is shown by the simulation result that the improved particle swarm algorithm is the fastest in the tracking speed and the least of output harmonic contents. The algorithm not only gives full play to the advantages of PV power generation but also improves the power quality of distribution system.