Development of simplified loss models for distribution system analysis

This paper proposes a methodology to derive a simplified model for distribution system loss analysis. According to the typical daily load patterns and the energy consumption of customers, the hourly loading of distribution transformers can be solved. A three-phase load flow program is applied to calculate the feeder power flow so that the hourly feeder loading will be the same as that obtained by the field test. The hourly primary conductor loss, secondary conductor loss, transformer copper loss and core loss are then solved according to the mathematical modeling of system components. The sensitivity analysis of system loss with respect to the feeder loading, power factor, feeder length, transformer capacity is then performed to derive the simplified loss model of distribution feeders. A distribution feeder of Taipower system is then selected for computer simulation to demonstrate the effectiveness of the proposed method. By applying the simplified loss model derived, the daily loss pattern of distribution feeders is solved according to the actual hourly feeder loading. It is concluded that the proposed methodology provides a useful tool for distribution engineers to estimate the operation efficiency of distribution systems in a very effective manner