Load Flow Analysis and Reactive Power Compensation Subhajit Mukherjee Department of Electrical Engineering Brainware Group of Institutions-SDET Barasat, Kolkata 700125, India subhobesu2008@gmail.com Arijit Ganguly Department of Electrical Engineering Brainware Group of Institutions-SDET Barasat, Kolkata 700125, India arijit.ganguly.2013@gmail.com Dr Ajay Kumar Datta Electrical Engineering Department Brainware Group of Institutions-SDET Barasat, Kolkata 700125, India ajaydatta2007@gmail.com Asoke Kumar Paul Department of Electrical Engineering Brainware Group of Institutions-SDET Barasat, Kolkata 700125, India asokepaul@yahoo.co.in Abstract— This paper deals with load flow analysis and compensation of reactive power in an electrical machine lab. This lab is used for conducting experiments on various DC generators whose prime mover is an induction motor, DC motors and Induction motor with variable load and rectifier unit. Other than electrical machines, there are large number of fluorescent lamps, exhaust fans and celling fans in the lab. For each induction machine, fan and fluorescent lamp, the reactive power drawn has been experimentally measured. The electrical load analysis in the lab has been simulated using ETAP (Electrical Transient and Analysis Program) software. The calculation of reactive power compensators has been done using ETAP software and compensators have been installed in the lab for power factor improvement. Further, using ETAP software, the lab design has been modified to reduce the load side voltage fluctuation. With the introduction of this reactive power compensator in the lab by capacitor bank, as calculated by ETAP software, the reactive power drawn by the lab has been reduced and consequently the line current drawn by the lab has reduced. This has reduced the load side voltage fluctuation and losses in line have been reduced. Keywords— ETAP, Reactive power, Active power, Compensating capacitor, VAR compensators. Harmonic analysis. I. INTRODUCTION A large institute or an office complex requires power factor improvement for stability of power system and to improve load side voltage. Power factor is the ratio of active power consumed by the total power drawn (apparent power) by a unit (Lab / Housing complex / Shopping complex / Industry) containing electrical equipment, lights, fans and electrical gadgets. It is a measure of how efficiently the electrical power is converted into useful work output. Most industrial loads require active power and reactive power to produce a useful work. An industrial consumer pays for both active and reactive power. Decrease in reactive power consumption reduces the electric bill of a company. The basic idea of this work (reactive power compensation) is to estimate the reactive power using ETAP software and calculation of capacitor required for compensation to make the power factor nearly unity. This reactive power shall be supplied, so that current drawn from the substation / generating station is reduced. This in turn reduces losses in the transmission line and reduces the losses in the transformer. An electrical load of unity power factor is an ideal load. A load of lower power factor (say 0.8) results higher loss in the supply system and higher bill for the consumer. A relatively small improvement in power factor shall reduce the losses significantly. Typical power factor of laboratory loads and domestic loads are given in Table-1. Reactive power compensation can be used throughout the day and night. However, in the peak load hour (5.00 pm to 11.00 pm), more rebate is given if reactive power drawn is less (i.e. power factor is nearer to unity). Thus, reactive power compensation is more useful during peak hour. When the high power consuming loads are known in a lab or in a house, suitable compensating devices can be designed using ETAP software. This shall reduce the electric bill of the lab / house. A low power factor due to induction motor and transformer can be compensated by addition of power factor correcting equipment. When there are DC motors driven by converters and AC motors driven by inverters, there will be distorted current waveform. To improve the power factor we need harmonic filters. The input power factor for inverter driven AC motors is in the range of 0.50 to 0.75. An extensive literature survey has been conducted to improve the power factor in the lab. The paper [1] gives the impact of power factor correction on the distribution network. TABLE I. TYPICAL POWER FACTOR OF LABORATORY AND DOMESTIC LOAD Sl. No. Item Power Factor Typical power (i) Ceiling fan 0.5 to 0.7 80 W (ii) Control room fan 0.5 to 0.6 80 W (iii) Exhaust fan 0.6 to 0.7 100 W (iv) Washing machine 0.6 to 0.7 1000 W (v) Vacuum cleaner 0.6 to 0.7 1000 W (vi) Window type Air Conditioner 0.6 to 0.85 1000 W (vii) Refrigerator 0.6 to 0.7 150 W 2018 International Conference on Computing, Power and Communication Technologies (GUCON) Galgotias University, Greater Noida, UP, India. Sep 28-29, 2018 978-1-5386-4491-1/18/$31.00 ©2018 IEEE 211