Q: big problem with my iMac randomly sleeping

Well, i've got a big problem with my iMac 21' bought in summer 2015.
Till this afternoon, it randomly fall asleep often each 5 secondes sometimes let me work longer few minutes...

I still had the problem in 'repair mode'... i've reset PRAM/VRAM and try a lot of things without success.

Here is what i get in energy log, does it spot something anormal ?

UUID: AB149E07-80F7-422C-8D80-E46A5DD40F78

2016-08-18 16:58:15 +0200 Notification        Display is turned off                                                               

2016-08-18 16:58:15 +0200 Assertions          PID 97(hidd) Summary UserIsActive "com.apple.iohideventsystem.queue.tickle" 00:41:21  id:0x0x900000215 [System: DeclUser kDisp]         

2016-08-18 16:58:15 +0200 Assertions          Kernel Idle sleep preventers: -None-         

2016-08-18 16:58:16 +0200 Sleep               Entering Sleep state due to 'Low Power Sleep': Using AC 1555 secs

2016-08-18 16:58:19 +0200 Wake Requests       [*proc=mDNSResponder request=Maintenance inDelta=7198]          

2016-08-18 16:58:19 +0200 PM Client Acks      Delays to Sleep notifications: [com.apple.apsd is slow(2226 ms)]          

2016-08-18 17:24:09 +0200 Kernel Client Acks  Delays to Sleep notifications: [AppleThunderboltNHIType2 driver is slow(msg: WillChangeState to 2)(437 ms)] [AppleAHCIDiskQueueManager driver is slow(msg: SetState to 0)(689 ms)]          

2016-08-18 17:24:09 +0200 Assertions          PID 90(mDNSResponder) Created MaintenanceWake "mDNSResponder:maintenance" 00:00:00  id:0x0xd0000042e [System: DeclUser BGTask SRPrevSleep kCPU kDisp]         

2016-08-18 17:24:09 +0200 Assertions          Kernel Idle sleep preventers: IODisplayWrangler         

2016-08-18 17:24:09 +0200 Notification        Display is turned on                                                                

2016-08-18 17:24:11 +0200 Assertions          PID 90(mDNSResponder) Released MaintenanceWake "mDNSResponder:maintenance" 00:00:02  id:0x0xd0000042e [System: DeclUser BGTask kDisp]         

2016-08-18 17:24:11 +0200 Wake                Wake from Normal Sleep [CDNVA] due to XHC1/HID Activity: Using AC          

2016-08-18 17:24:11 +0200 Kernel Client Acks  Delays to Wake notifications: [AppleHDADriver driver is slow(msg: SetState to 1)(404 ms)] [AppleHDADriver driver is slow(msg: SetState to 1)(475 ms)] [en0 driver is slow(msg: DidChangeState to 2)(2008 ms)]          

2016-08-18 17:24:11 +0200 PM Client Acks      Delays to Wake notifications: [AirPort configd plug-in is slow(303 ms)] [IPConfiguration is slow(303 ms)]          

2016-08-18 17:25:15 +0200 Assertions          PID 76(apsd) Released InteractivePushServiceTask "com.apple.apsd-connectionestablish-sandbox.push.apple.com" 00:01:02  id:0x0x1200000440 [System: DeclUser IPushSrvc kDisp]         

2016-08-18 17:26:16 +0200 Assertions          PID 76(apsd) Released InteractivePushServiceTask "com.apple.apsd-connectionestablish-sandbox.push.apple.com" 00:01:01  id:0x0x120000044a [System: DeclUser IPushSrvc kDisp]