ANALYSIS AND MINIMIZATION OF POWER LOSS IN EEPCo's TRANSMISSON GRID NETWORK

Abstract

This research work is intended on the analysis and minimiz ation or bulk power transmission loss in high voltage transmission grid networks. A literature review on the determination of bulk transmission capacity and energy losses are provided. The basic problems were the computation of how much energy is being lost in transferring the electrical energy across the power network and the minimization of this loss by taking necessary technological measures. Appropriate methods which take in to account the available data were chosen to quantify the capacity and energy los ses for the existing transmission network of EEPCo. A modeling of electrical system elements was first developed to have a complete one line diagram of the exi s ting grid network using ETAP-PowerStation environment. A load flow analysis was then run with substation peak loads collected from EEPCo offices provided at Appendix C. The load flow solution provided the total peak capacity loss of the whole grid network, peak losses on lines of different voltage levels namely, 45, 66, 132, 230 and 400 kV networks, and peak losses on transformers which extend from generation to HV / l 5 kV distribution transformers. Hence, the loss shares of each component were determined. The impact of variation of line loading and length on transmission losses was analyzed f or each voltage level with single and double circuit line models. The "Loss Factor - Load Factor" method was employed to determine the annual average power loss and hence the annual energy loss. This method is based on the empirical f ormula to determine the Loss Factor, which is then used to derive the annual average capacit y loss from the annual peak loss. The annual peak loss was determined from load flow solution. Detail discussion of the method is provided in the literature section and the analysis throughout the study was undertaken in this method. This study focused on methods to improve the efficiency of the grid. Industry-accepted methods were appli e d to evaluate various loss-reduction methods for the operating grid or EEPCo. Three methods of t ransmission line upgrading were undertaken to minimiz e the power loss of EEPCo ' s transmission grid from the exist ing state. The methods includ e lin e double circuiting, line nominal voltage uprating and reactive power compensation. Collective effects were also analyzed by applying two methods at a time. Candidate lines to be upgraded for loss reduction were chosen. For double circuit loss reduction method of this study, 55% of 45 kV lines, 40% of 66 kV lines and 30% of 132 kV lines were proposed to be upgraded. The selected lines are higher power dissipating lines determined from the load flow solution. For voltage uprating technique of loss reduction, 45 and 132 kV voltage levels were chosen to be uprated. All 45 kV lines were decided to be upgraded to 66 kV whereas 132 kV lines which lie in the main loops of the grid network were selected to be uprated to 230 kV. For reactive power compensation method of loss reduction, candidate buses were selected for compensation. The bus voltage profiles were determined from the load flow solution to select buses with worst voltage profiles. Shunt capacitors were connected to under voltage buses while shunt reactors to overvoltage buses. The annual energy gains due to loss reductions were determined for each method of loss reduction. Such energy gains were then expressed in terms of financial profits. Finally, the study ended with conclusions and recommendations.