As the requirement of mini water turbine merging into local area network is constantly increasing

frequently merging of the mini water turbine has become an important problem.To improve the safety and reliability of parallel operating mini hydroelectric power system

aiming at solving the problem that the time of merging is too long and the accuracy is too long

a design procedures of automatic synchronized system is proposed

how use the input multiloop feed-back second order active low pass filtering to get the timing voltage is analyzed

the constant lead time and catch the angle of phase lead are ensured.The design principle and realization scheme of controller are introduced in detail.The result of experiment indicate that this automatic synchronized system has the character of quickly and exactly simultaneous

and small impact to the system

at the same time it increases the precision of paralleling.