white Gaussian noise awgn

how I can add white Gaussian noise restricted to 1% of the measurements ? and how I can add white Gaussian noise restricted to constant value(i.e. 0.01) ?

[KALYAN ACHARJYA]

Can you elaborate more?

[Kh zaa]

I am actually not familiar with awgn but I got an information that I need to add awgn restricted to 1% of the measurements. My project is to collect measurements from a power system and then perform a controller. Thanks in advance