Load Coefficients (Load Varying with Voltages)

June 26, 2014
It is crucial to comprehend how the electric load reacts to changes in the supply voltage, especially when voltage reduction is now being utilized more often by utilities as means to reduce electric stress and demand response.

It is crucial to comprehend how the electric load reacts to changes in the supply voltage, especially when voltage reduction is now being utilized more often by utilities as means to reduce electric stress and demand response. After voltage reduction was implemented at a specific station, various engineering departments review the load change and compare the impact to their models and expectations. Often, the results don’t concur with their analysis, mainly due to the lack of modeling proper load coefficients. In the next paper, I can discuss the impact of voltage reduction on the substation transformers, sub-transmission feeders and the transmission system.

There are three types of loads, also known as load coefficients:

  • Constant power load
  • Constant current load
  • Constant admittance (inverse of the impedance) load

Even though several load flow programs models the electric load as constant power only, the other two types play a key role as well. Most modern equipment is of a constant power load type. The main difference between these types is in their response to changes in voltage....(Read rest of "Load Coefficients"...)

About the Author

Ahmed Mousa | Principal Engineer/Adjunct Professor/Board Member/Founder & CEO

Ahmed Mousa, M.S.E.E., has over 12 years of experience in transmission, sub-transmission, substations and distribution systems with industry leaders such as Consolidated Edison, PSE&G, PEPCO, and First Energy. He is a subject matter expert in transmission/sub-transmission, distribution and substation planning. Ahmed has years of expertise conducting PSS/E load flows, i.e. forced & scheduled outages analysis, phase angle studies, voltage analysis, network/non-network load transfers. Ahmed provides analysis and support during heat waves, storms and other system emergencies.

Mr. Mousa is an Adjunct Professor at New Jersey Institute of Technology (NJIT) teaching advanced topics graduate electrical engineering courses.

Mr. Mousa serves on the New Jersey Association of Energy Engineers board as a board member.

Mr. Mousa is currently the Principal Engineer at PSE&G in the Electric Delivery Planning section, where he is responsible for managing power system generation, transmission and distribution simulation studies, developing the short/ long range substation forecasts, analysis and load relief, performing short circuit studies, performing breaker duty analysis, developing transmission and distribution station and feeder designs, reviewing large customer demand proposals. Mr. Mousa is responsible for all Distributed Energy Resources technical evaluations and interconnection agreements.

Mr. Mousa is the Founder/CEO of The Electric Bridge Consulting firm assisting large and small utilities, colleges/universities & consulting firms by providing electric utility services, educational/training services, consulting services, leadership seminars, career consulting, lecturing services, electric professional engineering courses & national & international webinars. 

Mr. Mousa was responsible for the short term, long term (1/5/10/20/30 years), and emergency planning for the area substation, transmission / sub-transmission feeders and the 4 kV system at Consolidated Edison. He has conducted several studies on the impact of electric vehicles, distributed generation, steam to AC conversion, energy efficiency models, and R&D initiatives on the distribution and transmission system.

Mr. Mousa was the project manager for a SCADA GE XA21 Energy Management System and the project manager and project engineer for President Obama’s Department of Energy stimulus grant for Consolidated Edison’s 4 kV system.

Awards include the 2009 3rd Quarter Distribution Engineering ALVA Award for 21st Century Leader, the 2012 “Sustain Energy Reliability” Team Award, and the 2013 Excellence in Design and Genius Engineer (EDGE) Award Nominee for “Developed Load Calculation Tools for System and Transmission Operations.” He has over eight years of experience in providing training in a wide range of subjects including PSS/E, 4 kV systems, distributed generation grid adoption, system operation outage analysis, transformer ratings, voltage studies, basic and advanced power flow, intermeshes, phase angle studies, capacitor bank impact on the grid, smart grid, plant information (PI), post contingency analysis, voltage reduction, and conservation voltage optimization. Mr. Mousa received his Bachelor's Degree in Electrical Engineering from Stony Brook University and later a Master's Degree in Electrical Engineering from Manhattan College and has completed the Siemens PTI Distribution and Transmission courses.

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