A Theoretical Line Loss Calculation Of Electricity Power Flow

The rate of power transmission losses, which had caught much attention of power enterprises and many related organizations, plays a very important role in evaluating the economics of a power system. Since the reform of the power industry, power transmission losses have directly affected the power price, which is vital to the benefit of enterprises. So accurately calculability of power transmission losses is very important not only to the evaluation of power transmission losses management, but also to the formulations of losses decreasing measurement.Firstly existing methods for calculation of the theoretical transmission energy losses is investigated in detail in this paper, and the limitation of them is also pointed out. Various kinds of calculation methods are applied under different requirements on the result precision and scale of the data collected. There are calculation methods of losses factor, equal square root of current and equivalent node power. But none of them added the effect of the load curve and the generation curve. Calculation experience showed that some time the error caused by disregarding the load curve and generation curve may be from -23% to 29%, it is unacceptable.Based on the above research, a new method using electricity quantities flow to calculate power transmission losses is proposed in this paper, it covers the load flow calculation and non-linear constrained optimization. According to the 24 hours electricity quantities records of all transformer substations, this method uses electricity quantities flow to calculate the whole losses and the losses of every line. For the ill conditioned load flow caused by the error produced in the transformation from electricity quantities to average power, direct current load flow and sensitivity vector are presented to find out the ill node, then by adjusting the load curve and generation curve in a certain principle, which is shown in detail with several flow charts, a new operation mode is reestablished to ensure the convergence of the calculation. Optimal multiplier method is proposed to work out the least square solution according to ill conditioned structural power network. The electricity quantities flow method enhances the reliability and accuracy of the calculation of the power transmission losses.