Energy Management Studies

Overview

The electrical power required by motors to operate conveyors in a baggage handling system (BHS) is essential for designing the overall BHS. In many systems, numerous conveyors grouped into zones are started simultaneously due to the motor control configuration, such as soft starters, known as Zone Methodology. In this configuration, multiple conveyors are activated simultaneously, and they run continuously until the zone has been cleared of bags for a specified period, typically 10 minutes or more. This approach can result in running a large number of conveyors to transport a small number of bags during off-peak hours. The implementation of Variable Frequency Drives (VFDs) throughout the BHS eliminates the need for conveyor zones, allowing for targeted control and increasing energy efficiency by running motors only when necessary.

Small Group Methodology

An alternative zoning strategy is the Small Group Methodology, where conveyors run only when bags are present. Downstream conveyors are activated seconds before bags reach them and deactivate a few seconds after the last bag exits. This method reduces unnecessary conveyor operation and achieves significant energy savings.

Simulation and Verification

BNP uses simulation to verify the benefits of the Small Group Methodology. This approach involves activating motors when a bag approaches within a certain distance (configurable to three seconds of travel time) and deactivating them after the last bag exits the conveyor, with varying sleep delays (1, 2, 3, 5, and 600 seconds) examined. In contrast, the Zone Methodology simulation set a fixed sleep delay of 600 seconds for all conveyors. Energy consumption for each method was calculated over a 24-hour period.

Results

The bag systems have been simulated using the Zone Method and the Small Group Method to quantify the runtime and the number of starts and stops of each conveyor. This data, combined with the motor energy requirements, is used to estimate the daily energy consumption of each approach. Simulations have identified opportunities to reduce airport energy costs by up to 33%. The graph below depicts the energy utilization for each methodology over the 24-hour study interval, showing significant energy savings with the application of the Small Group Methodology.