When a fault occurs, it is very hard to accurately locate the fault position using the data provided from limited PMUs, unless we install PMUs at all substations of transmission network.

• 一般来说，输电电网所安装的同步量测单元的个数，远少于电网上汇流排的个数，在一般正常的状态下，电力工程师可由这些有限个数的同步量测单元的讯号，得知电力系统状态的良窳。