Changing Nature of Loads and the Impact on Utilities


The penetration of new load types, such as (1) energy-efficient lighting such as Compact Fluorescent Lamps (CFLs), (2) residential appliances with Variable Speed Drives (VSDs), and (3) computers and relatively new consumer electronics technologies (e.g., flat-screen TVs) has increased in the last few years and is expected to increase further in the future. Some of the new load types, such as fluorescent lighting and appliances with variable speed drives are generally more energy efficient thereby reducing the overall demand and the peak demand. In particular, reduced peak demand can result in substantial cost reduction for the utilities as this reduces the need for expensive generation to meet peak demand. On the other hand, the new technologies are often detrimental to the power quality of the utility supply system due to the non-linear characteristic of the electronic components of the new technology (e.g., the ballast in Compact Fluorescent Lamps and the converter in variable speed drives). These nonlinear loads increase the harmonic levels of the supply voltage can potentially degrade the overall power factor of the system.


The advent of the electric car is on the horizon, which will have a significant impact on the utility load if significant penetration levels are reached. The challenge for the utilities will be to have sufficient generation and thermal capacity to supply the electric vehicle fleet and to eliminate any detrimental impact the electric vehicle battery chargers may have on power quality. High-penetration levels of electric vehicles also present an opportunity for the utilities in that (1) the electric vehicle load can be beneficial for load leveling if battery charging is controlled so that it occurs during offpeak hours and (2) the storage capacity of the electric vehicle batteries may potentially be utilized for regulation and other utility operation services.

In this DSTAR study, the impact of the new load types on usage profiles, harmonic injection, energy consumption, losses, power factor, and other utility concerns are assessed. With these loads aggregated to the feeder level in various ways, the impact on operation and planning functions was investigated and discussed. Some of these functions include:

  • Conservation voltage reduction
  • Reactive power management
  • Energy efficiency
  • Peak shaving strategies
  • Power quality and reliability concerns
  • Load control and Demand-Side Management (DSM) programs

The result of the study is a 168-page comprehensive report that (1) discusses and analyzes new and emerging load types and the technology behind them, (2) discusses the factors that drive consumers to adopt new technologies, (3) assesses utility perspectives on loads with regard to trends in demand, energy use, and power quality, power factor, (4) simulates and analyzes the potential impacts of aggregated load types on load curves, harmonic distortion levels, energy consumption, losses, and utility operation practices. The outline of the report is shown below.


The final report for this study can be downloaded from P12-6