Numerous measuring and controlling techniques based on the high precision GPS-clock available in power systems nowadays have a common problem

viz. the stability of the clock signal is very poor

thus these techniques can hardly meet the requirements of power systems

e.g. synchronous control with high reliability

phase difference measurement

and so on. By analyzing the GPS-clock error and combining the characteristics of the GPS-clock with the high precision oscillator

methods for correcting the GPS-clock on-line by comparing with the oscillator are proposed. As the GPS-clock is free from cumulative error and the high precision crystal oscillator is free from random error

the two clocks can be effectively combined. Through dynamically averaging the counting values between the second pulses and estimating the error of the second pulse

methods for correcting the GPS-clock on-line have been developed. The device for the high precision clock with high performance price ratio is designed

which has been successfully applied in traveling wave location.