Compressor protection and grid fault detection device
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Solution Overview
Problem
Compressors connected to an electrical grid experience rapid current increases due to voltage drops, leading to potential stalling and thermal overload, which can cause grid instability and require costly supplemental generation and energy storage solutions, necessitating a method to detect and mitigate faults at the individual compressor level.
Innovation Solution
A compressor monitoring system that includes a current monitor, averaging modules, and a control module to detect anomalies by calculating ratios of average current values and generating fault signals based on predetermined thresholds, as well as utilizing sensors for mass flow, temperature, vibration, and power factor to deactivate the compressor when faults are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage drops on the electrical grid, then the compressor's current increases dramatically, but this leads to motor stalling and thermal overload
Solution Approach 1:
The system performs preliminary detection of abnormal current conditions by continuously monitoring current and comparing it against threshold values. When current exceeds the threshold for a predetermined time period, the system activates the contactor to disconnect the compressor from the power source before thermal overload can occur, preventing damage in advance
Solution Approach 2:
The system implements feedback control by continuously measuring the compressor current, comparing it with predetermined threshold values, and automatically activating the contactor when abnormal conditions are detected. This closed-loop monitoring and response mechanism ensures the compressor is protected from thermal overload caused by voltage drops
2Object-affected harmful factors
If the compressor is disconnected during voltage drops, then thermal overload is prevented, but grid instability persists requiring supplemental generation
Solution Approach 1:
The system extracts the problematic compressor load from the electrical grid by automatically disconnecting it when abnormal current conditions are detected. The contactor opens the circuit between the power source and compressor, removing the destabilizing influence of the compressor's high current draw during voltage drops, thereby preventing further grid instability without requiring supplemental generation
3Measurement precision
If current monitoring with threshold comparison is used, then fault detection is achieved, but false positives may occur
Solution Approach 1:
The system employs dynamic threshold adjustment by determining the threshold based on the compressor's operating conditions, including startup phase detection. During startup, the system recognizes the natural high current draw and adjusts the threshold accordingly, preventing false fault detections. The threshold is not fixed but adapts to the compressor's operational state, improving both detection accuracy and reliability
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
A compressor monitoring system includes current and voltage monitors, current and voltage averaging modules, a control module, and a switch. The current monitor measures a current drawn by a motor of a compressor. The current averaging module generates first and second average current values based on the current measured by the current monitor. The voltage monitor measures a utility power voltage. The voltage averaging module generates first and second average voltage values based on the voltage measured by the voltage monitor. The control module selectively generates a fault signal when a first ratio is greater than a first predetermined threshold and a second ratio is less than a second predetermined threshold. The first ratio is based on the first and second average current values. The second ratio is based on the first and second average voltage values. The switch deactivates the motor when the fault signal is generated.