A New Approach to Economic Dispatching Using Load Bus Elimination Techniques

This paper presents a new technique to solving the economic dispatch problem based on a reduced order model of the original system. Loads are first modeled by their appropriate voltage-dependent models as load admittances. Load admittances are then added to the bus admittance matrix and their respective buses are eliminated. The obtained model is a reduced model of the original system. The admittance matrix is of the same order as the number of voltagecontrolled buses in the system. The variables of the reduced model are the voltage-controlled buses’ angles and active power generations. Newton Raphson method is used to calculate the angles and active generations of the reduced model while minimizing the operational cost. Load bus voltages and angles of the original system are then calculated by a direct method and load admittances are modified. The process is repeated until convergence is achieved. The simulation is carried out on IEEE 118 bus test system. A comparison between the new approach and the penalty factors method has been made. It is shown that operational cost is improved and solution time is significantly reduced when compared to the penalty factors method of economic dispatch.