Elevator Group Scheduling for Peak Power Reduction
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Solution Overview
Problem
Elevator systems in high buildings face high energy consumption and inefficiencies due to varying power demands during accelerations and decelerations, leading to peak energy usage and potential fuse overload, especially when multiple elevators require simultaneous power.
Innovation Solution
Implementing a scheduling method that uses call information to coordinate elevator movements, delaying accelerations and rescheduling peak power usage to match energy release during decelerations, thereby reducing overall energy consumption and peak demand, and utilizing the hoisting machine as a generator to feed back energy into the grid or local storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple elevators are operated simultaneously to serve passenger calls, then passenger service coverage is improved, but peak power demand increases causing fuse overload risks
Solution Approach 1:
The control system performs preliminary scheduling of elevator runs based on predicted call patterns and energy availability. By pre-planning which elevators operate when, the system avoids simultaneous high-power accelerations and ensures fuse current limits are not exceeded, while still maintaining adequate passenger service coverage through optimized elevator dispatching.
Solution Approach 2:
The system dynamically adjusts elevator operation schedules based on real-time energy conditions and call patterns. The scheduling is flexible and adaptive, allowing the system to optimize the balance between passenger service coverage and peak power demand by shifting non-critical elevator runs to periods of lower power demand or higher energy availability.
2Speed
If accelerations are performed quickly to reduce travel time, then passenger transit speed is improved, but energy consumption increases due to high power demands
Solution Approach 1:
The system uses periodic acceleration and deceleration patterns that are optimized for energy efficiency. By scheduling accelerations to coincide with periods when energy is available (including regenerative periods when other elevators are decelerating), the system maintains acceptable transit speeds while reducing overall energy consumption through rhythmic, coordinated operation cycles.
Solution Approach 2:
The system converts the energy that would normally be lost during deceleration into useful energy by using regenerative braking. When elevators decelerate, the hoisting machine acts as a generator, transforming kinetic energy into electrical energy that can be used to power subsequent accelerations, thereby reducing net energy consumption while maintaining transit speeds.
3Use of energy by moving object
If the hoisting machine operates as a generator during deceleration to recover energy, then energy efficiency is improved, but control complexity increases
Solution Approach 1:
The control system merges the functions of acceleration control, deceleration control, and energy management into a unified scheduling framework. By coordinating multiple elevators' operations and combining regenerative energy from decelerating elevators with the needs of accelerating elevators, the system achieves improved energy efficiency while managing control complexity through integrated, centralized control logic.
Data Source
AI summary
Call information can be used for scheduling runs of elevators in a group of elevators. The scheduling is done so that based on the call allocations a schedule of expected movements, accelerations and decelerations can be computed. Then the movements, accelerations and decelerations may be controlled in order to improve energy efficiency or for controlling the movement in such manner that the energy consumption peaks or duration of these peaks is reduced.