Unbalanced three phase load flow programming using Matlab

Abstract

Electric utility industry is undergoing dramatic changes due to privatization, deregulation and competition in electricity markets in many leading countries. As a consequence, increasing wheeling transactions lead to a growing demand of transfer capabilities. In this new environment, a demand for flexible power flow control is becoming a technical need because the increase in the level of risk and uncertainty associated with transmission operation and investment. The goal of this project is a derivation of a mathematical model of unbalance (three-phase) load-flow of electric systems. The proposed model is suitable for active and reactive power flow control in transmission networks operating under either balanced or unbalanced conditions. An existing Decoupled NR (Newton-Raphson) based three-phase power flow program has been upgraded to include the proposed model. The power flow equations pertaining to power network are solved in a unified single-frame of reference leading a very good iterative solution. In this unified solution, nodal voltage state variables (voltage magnitudes and angles) are computed simultaneously through the iterative process. Hence, the algorithm exhibits quadratic convergence characteristic regardless of the network size. Validation of the proposed model is carried out in a benchmark network operating under balanced conditions. Matlab is used as a powerful tool to write the code which its algorithm is presented later.Electric utility industry is undergoing dramatic changes due to privatization, deregulation and competition in electricity markets in many leading countries. As a consequence, increasing wheeling transactions lead to a growing demand of transfer capabilities. In this new environment, a demand for flexible power flow control is becoming a technical need because the increase in the level of risk and uncertainty associated with transmission operation and investment. The goal of this project is a derivation of a mathematical model of unbalance (three-phase) load-flow of electric systems. The proposed model is suitable for active and reactive power flow control in transmission networks operating under either balanced or unbalanced conditions. An existing Decoupled NR (Newton-Raphson) based three-phase power flow program has been upgraded to include the proposed model. The power flow equations pertaining to power network are solved in a unified single-frame of reference leading a very good iterative solution. In this unified solution, nodal voltage state variables (voltage magnitudes and angles) are computed simultaneously through the iterative process. Hence, the algorithm exhibits quadratic convergence characteristic regardless of the network size. Validation of the proposed model is carried out in a benchmark network operating under balanced conditions. Matlab is used as a powerful tool to write the code which its algorithm is presented later.