3D Surge Map Control for Chiller Compressor Stability

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Solution Overview

Problem

Chiller controllers face challenges in achieving energy efficiency while avoiding surge conditions, which can cause damage to compressor systems due to unstable operation at varying load conditions, temperature, pressure, and vane positions.

Innovation Solution

A three-dimensional surface map is generated and used to control chiller setpoints, detecting surge events and calculating points in a coordinate system involving prerotation vane position, differential pressure, and compressor motor variable speed drive frequency, allowing for dynamic control to prevent surges and optimize energy efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If chiller parameters are controlled to reduce power consumption, then energy efficiency is improved, but surge conditions occur causing compressor damage

Engineering Contradiction:

Improvepower consumptionVSAvoidcompressor stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system performs preliminary actions by detecting surge conditions through pressure differential monitoring and predicting potential surge events before they occur. The controller proactively adjusts operating parameters to prevent surge conditions, rather than reacting after damage occurs. This includes calculating surge margins and adjusting compressor speed or inlet vane position in advance to maintain safe operating conditions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements continuous feedback by monitoring pressure differentials across the compressor, comparing actual values against predicted surge conditions, and automatically adjusting control parameters. The feedback loop includes real-time detection of surge events, analysis of the three-dimensional parameter space (compressor speed, inlet vane position, pressure differential), and dynamic adjustment of operating points to avoid surge regions while maintaining energy efficiency.

Inventive Principle:

Principle #23Feedback

2Reliability

If traditional surge avoidance methods are used, then compressor protection is improved, but energy efficiency deteriorates due to conservative operating limits

Engineering Contradiction:

Improvesurge preventionVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system transitions from static, conservative surge avoidance limits to dynamic, adaptive operating boundaries. The controller continuously updates the three-dimensional surge map based on real-time conditions including compressor speed, inlet vane position, and pressure differential. This allows the system to dynamically expand operating limits into previously conservative zones, enabling lower power consumption while maintaining surge protection through real-time adaptation to changing conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes operating parameters by optimizing the relationship between compressor speed, inlet vane position, and pressure differential. Instead of maintaining fixed conservative limits, the controller adjusts these parameters dynamically based on the calculated surge margin and current operating conditions. This allows the system to operate closer to optimal efficiency points while still preventing surge through coordinated parameter adjustment.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If real-time surge detection and control is implemented, then system reliability is improved, but control system complexity increases

Engineering Contradiction:

Improvesurge detection accuracyVSAvoidcontroller complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The controller segments the complex control problem into distinct functional modules: pressure differential sensing, surge condition prediction based on three-dimensional parameter analysis, surge margin calculation, and independent control actuation. This modular segmentation allows each function to be optimized separately and simplifies the overall control architecture, making the system more manageable despite the increased sophistication required for accurate surge detection and prevention.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8726678B2Controllers and methods for providing computerized generation and use of a three dimensional surge map for control of chillers

Publication Date: 2014.05.20 TYCO FIRE & SECURITY GMBH

AI summary

A controller for a chiller includes processing electronics configured to detect a plurality of surge events. The processing electronics calculate a point for each detected surge event in at least a three dimensional coordinate system. The three dimensional coordinate system describes at least three conditions of the chiller when the surge event was detected. The processing electronics are configured to calculate a surface map for the at least three dimensional coordinate system using the calculated points. The processing electronics are further configured to control at least one setpoint for the chiller using the calculated surface map.