PowerEL stands for Power Enterprise Linux, it originates from a requirement to have a fully free open source distribution for the IBM POWER 8 and higher platform.
The distribution takes it's inspiration and origin from various Open Source Enterprise Linux distributions such as Red Hat, CentOS, Oracle Linux, Fedora, SuSE, and others.
PowerEL has been optimized for specific CPU features, such as IBM Power8 or higher and Intel x86 AVX or higher, so it only works on cpu's with at least this set of features available.