Coordinated Equipment Staging to Reduce Peak Energy Demand Charges
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Solution Overview
Problem
Central plants face challenges in managing peak energy consumption and demand charges due to simultaneous staging of HVAC equipment, leading to high energy spikes, which are difficult to avoid while ensuring efficient heating and cooling loads are met.
Innovation Solution
A controller system that coordinates equipment staging across multiple subplants by detecting staging events and preventing secondary subplants from activating until a predetermined time period has elapsed since the initial staging, thereby reducing peak energy consumption and demand charges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple subplants stage their equipment independently to meet cooling loads, then the heating and cooling loads are met efficiently, but the peak energy consumption increases due to simultaneous staging spikes
Solution Approach 1:
The patent combines the control functions of multiple independent subplant controllers into a centralized controller that coordinates equipment staging across all subplants. This merging allows the system to maintain efficient load meeting while preventing simultaneous staging events that cause peak energy consumption spikes.
Solution Approach 2:
The controller detects staging events in one subplant and preemptively prevents simultaneous staging in other subplants by evaluating time periods since previous staging events. This preliminary action avoids the harmful stacking of energy spikes before they occur.
2Speed
If equipment is staged simultaneously to respond to increased cooling load, then the cooling demand is met quickly, but the demand charge increases due to high peak energy consumption
Solution Approach 1:
The controller performs preliminary evaluation of staging events by detecting when equipment in one subplant is staged and preemptively preventing simultaneous staging in other subplants. This timing-based coordination maintains quick response to cooling demands while avoiding the harmful stacking of energy consumption spikes that increase demand charges.
Solution Approach 2:
The patent converts the potentially harmful effect of simultaneous staging into a benefit by using the timing information from one subplant's staging event to coordinate and optimize the staging of other subplants. This coordination transforms what would be harmful stacked spikes into a controlled sequence that meets demand charges requirements.
3Ease of operation
If subplant controllers operate independently without coordination, then each subplant can be controlled简单地, but the overall system experiences stacked energy consumption spikes
Solution Approach 1:
The patent merges the independent control operations of multiple subplants into a coordinated system through a centralized controller. This combination maintains the operational simplicity of individual subplant control while adding the necessary coordination layer to prevent stacked energy consumption spikes, thus resolving the contradiction between simplicity and energy efficiency.
Data Source
AI summary
A controller for multiple groups of equipment detects a staging event for a first group of equipment and determines when the staging event occurs. The controller determines whether a predetermined time period has elapsed since the staging event for the first group of equipment has occurred and prevents a second group of equipment from staging in response to a determination that the predetermined time period has not elapsed since the staging event for the first group of equipment has occurred. Preventing the second group of equipment from staging reduces peak energy consumption during the predetermined time period and reduces a demand charge based on the peak energy consumption.