Modeling and Simulation of Unbalanced Distribution Systems for Time-Domain Analysis under Different Operating Conditions

In this paper, a comprehensive model of the IEEE 13 node power distribution system is modeled and simulated according to the governing differential equations of the system. The unbalanced nature and mutual coupling of the system are considered. Moreover, different types of loads such as concentrated, distributed loads and capacitor banks are taken into consideration. Various case studies of variable R/X ratio for line branches as well as load factor are investigated. The solution of the power distribution system is compared to a power-flow program and the results are verified with an acceptable range under different R/X and load factor ratios. It is found that the maximum voltage percentage error is less than 1% between the proposed solution and the forward/backward power flow solution. Moreover, the greatest phase error is found to be less than one degree between the two solutions. In general, the maximum voltage percentage error increases with increasing the R/X ratio or load factor.