Generator Load Angle Determination via Electrical Parameters
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Solution Overview
Problem
Existing methods for determining the load angle and rotor angle in electrical power generators, especially during high load conditions and transient periods, are inaccurate due to magnetic saturation and require additional costly components, making them unsuitable for small synchronous generators and out-of-step protection.
Innovation Solution
A method that measures the field current to derive the open circuit voltage, combined with terminal voltage and current measurements, to accurately determine the load and rotor angles without needing additional components like optical encoders or sensors, allowing for precise detection of out-of-step conditions at a lower cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical encoders or additional sensors are used to determine rotor angle, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The generator uses its own existing sensors (voltage and current sensors) to determine the load angle, without requiring external measurement devices. The method extracts rotor position information from the generator's inherent electrical parameters, making the system self-sufficient and avoiding additional hardware complexity
Solution Approach 2:
The patent replaces mechanical measurement systems (optical encoders, physical sensors on the rotor) with an electrical calculation method. By using voltage and current measurements combined with mathematical models, the mechanical measurement approach is substituted with an electrical field-based determination method
2Device complexity
If conventional load angle estimation methods are used during high load conditions, then device complexity is kept low, but measurement precision deteriorates due to magnetic saturation
Solution Approach 1:
The patent changes the approach from directly measuring rotor position to calculating it from electrical parameters (voltage, current, power factor). This parameter transformation allows accurate load angle determination during high load conditions by using the relationship between electrical quantities and rotor position, which remains valid even when magnetic saturation occurs
Solution Approach 2:
The patent introduces electrical parameters (voltage, current, power factor angle) as intermediaries to determine the load angle. Instead of directly measuring the mechanical rotor position, the method uses electrical measurements as intermediate steps to calculate the angle, providing accuracy during magnetic saturation while maintaining simple device complexity
3Reliability
If accurate load angle determination is achieved during transient periods, then out-of-step protection reliability is improved, but device complexity increases due to additional measurement requirements
Solution Approach 1:
The generator's existing voltage and current sensors serve dual purposes: normal operation monitoring and transient condition detection. The same sensors used for routine operation automatically provide data for load angle calculation during transients, eliminating the need for separate protection measurement systems
Solution Approach 2:
The measurement system is designed to serve multiple functions: normal operation monitoring, load angle determination during steady-state, and out-of-step protection during transient conditions. This multi-functionality achieves high protection reliability without increasing device complexity, as the same hardware infrastructure supports all operational modes
Data Source
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AI summary
Disclosed herein is a method of determining the load angle and/or rotor angle of a generator system (10), wherein the generator system (10) comprises a generator (11) with a generator terminal (15) for outputting electrical power generated by the generator (11), a transformer (16) and a point of common coupling, PCC, terminal (17), wherein the transformer (16) is arranged between the generator terminal (15) and the PCC terminal (17), the method comprising: determining the field current of the generator (11); determining the output voltage from the generator terminal (15), the output current from the generator terminal (15) and the power factor angle and/or the power factor of the output voltage and output current from the generator terminal (15), and determining the load angle of the generator system (10) in dependence on the determined field current, output voltage from the generator terminal (15), output current from the generator terminal (15) and the power factor angle and/or the power factor; and/or determining the output voltage from the PCC terminal (17), the output current from the PCC terminal (17) and the power factor angle and/or the power factor of the output voltage and output current from the PCC terminal (17), and determining the rotor angle of the generator system (10) in dependence on the determined field current, output voltage from the PCC terminal (17), output current from the PCC terminal (17) and the power factor angle and/or the power factor.