In this paper, an attempt is made to introduce various power theories for power network solution and its mathematical framework in view of load compensation. These are necessary to evaluate the efficiency and performance of the transmission, distribution systems and various electrical equipments. In order to compensate the load, it is required to know which components of the load power to be compensated. Under balanced and sinusoidal conditions, the power definitions and decompositions are well defined and are being in the practice. But, in the case of non-ideal source condition it is still in grey area. So in that context this article presents the current literature about the different power theories and the ideas for load compensation in non-ideal conditions.