| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that in the communication network of a distribution automation system, a communication speed is slow and a response time from packet transmission to reception, therefore, is long and fluctuates greatly, which, in a time synchronization procedure as network time protocol (NTP), significantly affects monitoring control and degrades time accuracy. <P>SOLUTION: In a distribution automation system, an operation status is inquired of each piece of equipment individually from a control unit and the equipment which received the inquiry notifies the control unit of their status information. A response time from inquiry until when status information is received is measured for every equipment, and the response time is notified to the equipment side by making use of a broadcast. A communication unit on the equipment side receives the response time and a timestamp by a timer synchronized to a radio clock, compares them with the time of day of its own timer, and, if a difference is greater than a given value, corrects the time of day of the timer. According to the present invention, a communication traffic volume needed for time synchronization control can be reduced to eliminate effects of delay time in a communication network, making it possible to realize highly accurate time synchronization. <P>COPYRIGHT: (C)2012,JPO&INPIT |
