## Thursday, November 20, 2014

### Load Factor, Coincidence Factor, Diversity Factor and Responsibility Factor

Load factor is average load of a system divided by its peak load. The higher the load factor is, the smoother the load profile is, and the more the infrastructure is being utilized. The highest possible load factor is 1, which indicates a flat load profile.

In the old days, load factor is often used for long term peak demand forecasting. The forecasters first develop a energy forecast. They then calculate the average hourly load. Finally by dividing the forecasted average load by a predefined load factor, they can obtain the forecasted peak. However, I would avoid using this method for long term load forecasting in today's world where high resolution data is available for load forecasting.

Coincidence factor is the peak of a system divided by the sum of peak loads of its individual components. It tells how likely the individual components are peaking at the same time. The highest possible coincidence factor is 1, when all of the individual components are peaking at the same time.

Diversity factor is sum of peak loads of all the components in a system divided by peak of the entire system. It is the reciprocal of coincidence factor. The higher the diversity factor, the more diverse the individual loads are in terms of peaking time. If the individual loads are peaking at the same time, the diversity factor is 1.

Coincidence factor and diversity factor are often used for top-down forecasting in transmission and distribution planning. After the corporate level forecast is developed, the planning team would get a quota telling the sum of the peaks from various regions. This quota is usually calculated by dividing the forecasted system peak by coincidence factor. The regional peak load forecasts can then be developed subject to the constraint of this quota.

Responsibility factor is the load of an individual component at the time of system peak divided by the peak load of this individual component. Responsibility factor tells how much of the component is contributing to the system peak. When a component peaks at the same time as the system, its responsibility factor is 100%.

Responsibility factor is often used in guiding demand side management. Utilities often get charged for its contribution to the peak of independent system operator. To avoid a high charge, a utility has to reduce the responsibility factor. This can be done by implementing various programs that help shift the peak. Similarly, responsibility factor is also used in rate making. A customer with high peak demand may not get high demand charge if the peak occurs during off-peak period of the utility system load.