To enable keepalives for all your stored sites:
Reference:
https://winscp.net/eng/docs/commandline#batchsettings
https://winscp.net/eng/docs/rawsettings#pingtype
winscp.exe /batchsettings * PingType=1
Reference:
https://winscp.net/eng/docs/commandline#batchsettings
https://winscp.net/eng/docs/rawsettings#pingtype