Heidari - TAVANIR CO.
Mokariha - Industrials and mines

Although conductor resistance is one of the most influential parameter in system loss calculation, But, system engineers in their studies on other aspects of system studies do not feel compled to reflect this importance, possibly because it does not affect the results of their study as such. As a consequence of this negligence the system loss calculation in most of the time is made with lack of sufficient accurancy. In all existing computer programmes for load flow study, it is a common practice to find conductor resistance at constant temperature e.g. 25 oc, 50 oc, 90 oc, where as, the fact is that, the resistance of loaded conductors in each region by itself is a function of ambient temperature, sun radiation and current passing through it , one cap easily appreciate that common practice in system study could lead to an. unacurate calculation of system losses. In this paper a computerized model of load flow study is proposed in which loaded conductors resistance is given as a function of environmental parameters as well as current passing through it. Based on this model the system engineers will insert the temperature of each region at time of study (Day or Night ) as the initial data to the computer with which the load flow study programme is Ran. Then , by knowing the current passing through each line, the resistances of loaded conductors are calculated and refed into the programme as a new conductors resistance. This process is continued untile the desired accurancy is reached. In this way the real system losses are calculated. Another particularity of this proposed model is that, by enteringa simple fixed data of conductors resistance, load flow study can be carried out for various season " Summer, Fall, Winter, Spring" in various load situations.