Abstract:Through direct estimation of transmission line resistance wire to realize the distribution network loss evaluation function, is difficult to accurately grasp the problem, it is proposed that the distribution network transmission line, the maximum allowable temperature into active power loss limit, thus establishing the method of transmission wire short thermal value. The environmental parameters of the heat balance equation of transmission line as state variables, according to the transmission wire coupling relationship between active power loss and resistance, temperature, differential equation of transmission line power loss change is derived, in order to establish the measurement equation; at the same time, considering the slow change of thermal balance equation parameters, establishing the state variable then, on the basis of space expression; transmission line active power loss rate, using the method of Calman filter is used to estimate the state variables. Thus, the function of distribution network wire loss assessment is completed, which provides the basis for the feasibility of short-term maximum current operation mode of distribution network power transmission line. The feasibility and effectiveness of the proposed method are verified by the measured data of the transmission line of 220kV distribution network in an area of Guizhou, Kaili.