how to create a scan to detect in 15 minutes this phase of transition as shown in the image

While images can be used to illustrate and clarifiy an already specific unambiguous objective definition, an image is not in and of itself a definition which can be used (at least by me) to create a scan for whatevere you are attempting to identify.

If you are trying to identify the "flat" part, maybe something like the following?

MAXH15 - MINL15 < 3 * ATR15

You can change 3 in the formula to adjust the sensitivity (the lower the value, the "flatter" it needs to be) and the 15s in the formula to adjust how many bars are being used in the calculation.