Parallel Generator Foldback Calibration for Current Sharing Balance
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Solution Overview
Problem
Conventional high-voltage direct-current (HVDC) electrical power generation systems with foldback control algorithms experience significant current sharing imbalances between paralleled generators due to small errors in voltage sense measurements, leading to inefficient load distribution.
Innovation Solution
A generator system with controllers that calibrate foldback control by using current sensors to determine sharing errors and adjust voltage outputs to correct for current sharing imbalances, employing equations to calculate offset voltages and regulation points, ensuring accurate load sharing between generators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If foldback control is used to share load power between parallel generators, then load sharing is achieved, but current sharing imbalance occurs due to small voltage sense measurement errors
Solution Approach 1:
The patent implements a feedback mechanism where each controller measures the actual current output of its generator and compares it with the desired current share. The calibration offset is adjusted based on the difference between actual and desired current sharing, creating a closed-loop control system that continuously corrects imbalances caused by voltage sense measurement errors.
Solution Approach 2:
The patent changes the voltage reference parameter by introducing a calibration offset that is added to the foldback voltage reference. This offset is dynamically adjusted to compensate for measurement errors, effectively modifying the voltage parameter to achieve accurate current sharing despite imperfect voltage sensing.
2Ease of operation
If a shallow voltage versus current curve slope is used to enable small voltage changes to cause large current changes, then load sharing control is improved, but current sharing imbalance increases due to voltage sense errors
Solution Approach 1:
The feedback mechanism measures actual current output and uses this information to adjust the calibration offset, compensating for the amplified effects of voltage sense errors on current sharing balance.
Solution Approach 2:
The system performs self-calibration by automatically adjusting its own voltage reference parameters based on measured current sharing performance, eliminating the need for external calibration equipment or manual adjustment.
3Extent of automation
If voltage sense measurement errors occur in the control system, then foldback control still operates, but one generator takes more current than it should while another takes less
Solution Approach 1:
The system uses feedback from current measurements to detect and correct the imbalances caused by voltage sense measurement errors, maintaining automatic load sharing despite sensing inaccuracies.
Solution Approach 2:
The patent introduces asymmetric calibration offsets for different generators based on their individual voltage sense measurement errors. Each generator receives a customized offset that compensates for its specific sensing inaccuracies, allowing the system to handle asymmetric errors effectively.
Data Source
AI summary
A generator system can include a first generator, a first controller operatively connected to the first generator to control a first generator voltage output, a second generator, and a second controller operatively connected to the second generator to control a second generator voltage output. The first generator and the second generator can be configured in a parallel generator configuration to share load power. The first controller and the second controller can be configured to provide foldback control. The first controller and the second controller can be configured to calibrate foldback to correct for current sharing imbalance between the first generator and the second generator.