VRF System Pressure Optimization Using Extremum-Seeking Control
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Solution Overview
Problem
Variable refrigerant flow (VRF) systems face challenges in optimizing power consumption and operational efficiency, particularly in determining the optimal pressure setpoints for outdoor units to minimize energy usage while maintaining effective heating and cooling performance.
Innovation Solution
The implementation of an extremum-seeking control (ESC) technique, which perturbs the current pressure setpoint with an excitation signal, monitors the resulting power consumption, estimates the gradient, and adjusts the setpoint to drive it towards zero, optimizing the total power consumption of outdoor VRF units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional control methods are used to manage outdoor VRF units, then the system operation is simple, but the power consumption cannot be optimized to an extremum
Solution Approach 1:
The patent implements a closed-loop feedback control system where the extremum-seeking controller continuously monitors system performance (power consumption) and adjusts the pressure setpoint accordingly. The controller uses feedback from power consumption measurements to drive the gradient toward zero, thereby optimizing energy usage dynamically while maintaining system operation.
Solution Approach 2:
The patent dynamically changes the pressure setpoint parameter to optimize power consumption. By treating the pressure setpoint as a variable parameter rather than a fixed value, the system can adapt to changing conditions and drive power consumption to its extremum through continuous parameter adjustment based on real-time measurements.
2Adaptability or versatility
If the pressure setpoint is fixed, then the control system is simple, but the system cannot adapt to changing conditions to minimize energy usage
Solution Approach 1:
The patent transforms the static pressure setpoint into a dynamic variable that adapts to changing system conditions. The extremum-seeking controller continuously adjusts the pressure setpoint based on real-time power consumption measurements, enabling the system to adapt to varying loads, ambient conditions, and operational requirements while minimizing energy usage.
Solution Approach 2:
The extremum-seeking control system is self-regulating and automatically adjusts the pressure setpoint without external intervention. The controller monitors power consumption and autonomously drives the system toward optimal operation by adjusting parameters, enabling the system to serve itself and adapt to changing conditions without complex external control.
3Loss of energy
If extremum-seeking control is implemented to optimize power consumption, then energy usage is minimized, but the control system complexity increases
Solution Approach 1:
The patent employs feedback control where the extremum-seeking controller continuously monitors power consumption and adjusts the pressure setpoint to minimize energy waste. The feedback loop drives the gradient of power consumption toward zero, automatically reducing energy waste while the controller manages the increased complexity through systematic control algorithms.
Data Source
AI summary
A variable refrigerant flow (VRF) system for a building includes a plurality of outdoor VRF units configured to heat or cool a refrigerant for use in heating or cooling the building and an extremum-seeking controller. The extremum-seeking controller is configured to determine a total power consumption of the plurality of outdoor VRF units, generate a pressure setpoint for the plurality of outdoor VRF units using an extremum-seeking control technique that drives the total power consumption toward an extremum, and use the pressure setpoint to operate the plurality of outdoor VRF units.