Looking at the subject of resale or reselling:
1) There are many others who believe there is nothing wrong to buy house near powerline
2) If the resell value is lower than other house, well your purchase price normally lower too

On safety side
A 2006  Medical College of Wisconsin review of studies on the subject revealed that:
-    46 percent of those studies found exposure to power frequency fields had no effect on subjects.
-    22 percent found that exposure resulted in DNA damage.
-    32 percent of the studies were inconclusive.

Like normal people, some may be sensitive to something and some may not. Some allergic to some and some are not.

Some guide provided something like this:

The minimum clearance distances o powerline are as specified:
Voltage (kV)----------------Minimum Clearance Distance (ft)
Up to 50--------------------  10
>50 to 200-----------------  15
>200 to 350----------------  20
>350 to 500----------------  25
>500 to 750----------------  35
>750 to 1,000--------------  45

How to identify what is the voltage on the powerline?
You can see that there are ceramic insulator (that white disc) near the tower on each side. Count the number of insulator

Transmission line Voltage -----------------​Number of insulator discs
110 kV -------------------------------------- 6–8
220 kV​--------------------------------------- 10–12
​400 kV--------------------------------------- 18–21

The 30m is far. It is your call even if I'd say it is okay 

this remind me of certain bank does not approve loan for unit near HTC.