Variable Speed Drive Reference Power for Accurate Energy Savings
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Solution Overview
Problem
The challenge in accurately determining the reference power value for variable speed drives (VSDs) leads to overestimation of energy savings, as conventional methods rely on nominal motor power, which can vary due to motor and actuator sizing discrepancies, hindering the effective use of energy-saving monitoring features.
Innovation Solution
A method utilizing cloud technology to remotely collect operational data from VSDs, generate a curve representing speed and power relationships, and determine a reference power value at the nominal speed, enabling accurate energy savings estimation by comparing VSD and direct on-line motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If nominal motor power is used as reference power value, then energy savings calculation can be performed, but the accuracy of energy savings estimation deteriorates due to motor and actuator sizing discrepancies
Solution Approach 1:
The patent changes the reference parameter from fixed nominal motor power to a dynamic reference power value that varies with motor speed. The reference power value is determined as the power consumed by the motor when operated at direct-on-line (DOL) control at each specific speed point, replacing the conventional constant nominal power reference with a speed-dependent reference that accurately reflects actual DOL power consumption at different operating conditions
Solution Approach 2:
The patent implements a feedback mechanism where the reference power value is continuously updated based on actual motor operating conditions. By monitoring motor speed and calculating the corresponding reference power value from DOL control characteristics, the system feedbacks an accurate reference value for energy savings calculation, eliminating the need for manual motor sizing adjustments and ensuring continuous accuracy across varying operating conditions
2Ease of operation
If conventional energy-saving monitoring features are implemented, then energy efficiency can be monitored, but the reliability of monitoring results deteriorates due to overestimation from inaccurate reference values
Solution Approach 1:
The patent enables the energy-saving monitoring system to self-correct by automatically determining accurate reference power values based on actual motor speed and DOL control characteristics. The system serves itself by using its own operational data to generate the reference values needed for accurate monitoring, eliminating dependence on external manual adjustments or predetermined nominal values that may not reflect actual operating conditions
Data Source
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AI summary
Disclosed is a method comprising collecting operational data associated with a motor controlled by a variable speed drive, wherein the operational data comprises at least speed values and power values of the motor; determining, based on the operational data, a reference power value corresponding to a nominal speed value of the motor; and estimating, based on the reference power value, an amount of energy saved by the variable speed drive compared to direct on line motor control.