Voltage Formula derived by Ohmic Calculation for AC Two-bus System with Constant Power Load P+jQ and Transmission Line Impedance R+jX

The AC two-bus system can be understood as the aggregation of the entire power system, in which the bus voltage and the load P,Q can be interpreted as the current operating voltage and the total consumers’ demand of the system. And the sending-end and receiving-end voltage of two-bus system can be the starting-point for step-by-step voltage calculation of multiple load points in a distribution line. Calculation of the voltages in two-bus system is meaningful. The voltage-power equation composed of bus voltages and load power P,Q for an AC two-bus system has been presented in publications. In addition, an explicit formula for calculating the receiving-end voltage of an AC two-bus system with line admittance G-jB recently has been announced. This formula can yield a unique and practical solution, however, the conductor parameters used in power system computation and provided by manufacturers have been mostly expressed by impedance R+jX, not by admittance G-jB. In this paper, the formulae for sending-end and receiving-end voltage of an AC two-bus system with line impedance R+jX are derived using ohmic calculation. And an explicit formula for calculating the receiving-end voltage of AC two-bus system represented by impedance R+jX is also introduced, from which a unique and feasible solution can be obtained. The line impedance data R+jX can be substituted directly into the proposed formula without any data conversion. Example calculations show that the results by the proposed formulae are exact and the same as those by existing methods.