Load flow analysis in power system using ETAP software

Abstract

ETAP (Electrical Transient Analysis Program) is the most comprehensive analysis tool for the design and testing of power systems available. Using its standard offline simulation modules, ETAP can utilize real-time operating data for advanced monitoring, real-time simulation, and optimization and energy management systems. It is invented and started in California, USA from1986. It is widely used for more than 30 years for power system studies across the world. ETAP has been designed and developed by engineers for engineers to handle the diverse discipline of power systems for a broad spectrum of industries in one integrated package with multiple interface views such as AC and DC networks, cable raceways, ground grid, GIS, panels, arc flash, WTG, protective device coordination/selectivity, and AC and DC control system diagrams. The project is based on load flow analysis of power system using etap software. Load flow analysis helps to determine the active power flow, reactive power flow, power factor, losses, bus voltage profiles etc. in the system. The study also target to analyse the load flow result outcomes, its improvement and mitigation. Here, initially we have considered a simple SLD and modelled it in the etap software. Additionally, the simulated results from the etap software for simple SLD are compared and validated with the manual calculation also. Further, the main SLD is constructed in etap with the detailed modelling of electrical equipment’s such as grid, transformers, loads etc. The project is performed with consideration of two configurations ‘Normal Configuration’ and ‘One_TR_Out Configuration’. The load flow study results are simulated for various operating conditions (maximum, minimum and normal) of generator and load. From the study results it is observed that during Minimum load flow case overvoltage’s are observed at 0.415 kV LV buses Bus3 & Bus5 as 107.7 %. However, with +2.5% tap setting of transformers T2 & T4 the voltages at Bus3 & Bus5 reduces within the voltage violation limit of ± 5%. During maximum load flow case it is observed that transformer T1 is supplying power to all downstream system of 6.6 kV and 0.415 kV (as the other two transformer’s T3 & T4 are out of service) causes overloading of transformer T1. To overcome this situation, the transformer T1 & T3 ratings are increased to 31.25 MVA using ONAF cooling; and OLTC tap limit to increased to ±15%. With this solution, it is observed that there is no overloading of any equipment an also the bus voltage profiles are well within the acceptable limit of ±5%.