Building HVAC system with multi-level model predictive control
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Solution Overview
Problem
Commercial HVAC systems face challenges in deploying model predictive control (MPC) due to the complexity of managing large numbers of building zones and the need to include airside power consumption models to optimize overall energy costs, as existing systems often neglect airside costs and struggle with real-time optimization.
Innovation Solution
A system comprising a high-level model predictive controller (MPC) and low-level airside MPCs that generate optimal airside and waterside load profiles to minimize total energy cost, incorporating airside and waterside power consumption models to manage both systems simultaneously, with thermal energy allocation and temperature modeling to optimize zone-level operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single combined control system is used for campus-wide HVAC optimization, then centralized optimization can be achieved, but the optimization problem becomes too large to solve in real time
Solution Approach 1:
The patent divides the campus-wide HVAC system into multiple building-level control systems, each independently optimizing its own building. This segmentation allows each control system to solve a smaller, manageable optimization problem in real-time while collectively achieving campus-wide energy optimization. The decomposition transforms one large intractable problem into multiple smaller solvable problems.
2Stability of the object's composition
If traditional temperature control is used to converge to desired set points, then temperature stability is achieved, but total energy consumption is not minimized
Solution Approach 1:
The patent uses predictive optimization to anticipate future temperature requirements and pre-adjust thermal energy storage systems (such as ice storage or hot water tanks) before peak demand periods. This preliminary action allows the system to meet future temperature set points with less energy by storing thermal energy during off-peak hours when electricity rates are lower, thereby minimizing total energy consumption while maintaining temperature stability.
Solution Approach 2:
The patent changes the control objective from simple temperature set point tracking to a multi-parameter optimization that includes energy cost minimization, thermal storage state, and predictive load forecasting. This parameter transformation allows the system to balance temperature stability with energy efficiency by adjusting control variables such as chiller operation schedules, storage tank temperatures, and HVAC equipment timing.
3Device complexity
If airside power consumption is excluded from optimization, then optimization complexity is reduced, but total energy cost optimization is incomplete
Solution Approach 1:
The patent merges the airside and waterside system models into a unified optimization framework that simultaneously considers both components. The airside model predicts HVAC equipment power consumption based on temperature set points and load conditions, while the waterside model predicts chiller and pump power consumption. By combining these models, the system achieves complete total energy cost optimization without prohibitively increasing complexity, as both models use similar predictive approaches and can be integrated into a single cost function.
Data Source
AI summary
A heating, ventilation, or air conditioning (HVAC) system for a building includes HVAC equipment configured to provide heating or cooling to one or more building spaces and one or more controllers. The one or more controllers include one or more processing circuits configured to generate energy targets for the one or more building spaces using a thermal capacitance of the one or more building spaces to which the heating or cooling is provided by the HVAC equipment, generate setpoints for the HVAC equipment using the energy targets for the one or more building spaces to which the heating or cooling is provided by the HVAC equipment, and operate the HVAC equipment using the setpoints to provide the heating or cooling to the one or more building spaces.