A linear electrical generator is a kind of device which can be used to wave energy converter, for directly converting mechanical energy of a floating structure into electrical energy. A wave farm consists of multiple wave energy converters in a sea area. In the present paper, a numerical model is proposed considering the interference effect in the multiple floating structures, and the controlling force of each linear electrical generator. Especially, the copper losses in the electrical generator is taken into account, when the electrical power is computed. At first, the controlling force coefficients are discussed to find their physical effects on heave motion. As a case study, the heave motion and electrical power of the three truncated cylindrical floating structures are estimated in the straight arrangement. And the average electrical powers are calculated in different distance of the floating structures.