Renewable Energy Plant Control System for Power Overgeneration
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Solution Overview
Problem
Existing control systems for renewable energy plants face issues with overgeneration due to rapidly increasing solar irradiance, leading to overcurrent protection trips and the limitation of active power but not current.
Innovation Solution
A method and system that measure power output and frequency deviation, generate error signals within predetermined limits, and apply these signals to a proportional-integral loop to control power flow between a renewable energy plant and an electric power grid, using a renewable energy plant control system to manage power output and frequency events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If closed loop voltage regulation and frequency droop control are used to maintain stable operation, then system stability is improved, but power overgeneration occurs during rapidly increasing solar irradiance
Solution Approach 1:
The control system performs preliminary action by measuring power output and frequency deviation, generating error signals within predetermined limits before applying them to the proportional-integral loop. This anticipatory control prevents power overgeneration by limiting the error signal to predetermined minimum and maximum power error limits, ensuring that the control response does not cause overgeneration during rapidly increasing solar irradiance while maintaining system stability
Solution Approach 2:
The invention changes the parameter of error signal limiting by applying the first and second error signals to a proportional-integral loop with predetermined minimum and maximum power error limits. This parameter change ensures that the control output remains within safe boundaries, preventing both overgeneration and under-generation while maintaining frequency stability
2Productivity
If the governor's PI loop compensates for cloud passage by increasing loop output, then power generation recovery is improved, but power overshoots the reference after cloud passes
Solution Approach 1:
The control system uses feedback by measuring power output from the renewable energy plant and determining a first difference signal between the measured power output and a power reference. The measured power output is fed back to the proportional-integral loop with predetermined limits, which automatically adjusts the control signal to prevent both under-generation during cloud passage and overshoot after cloud passes, thereby improving both recovery and control precision
Solution Approach 2:
The control system applies preliminary anti-action by generating a first error signal that is limited to predetermined minimum and maximum power error limits before being applied to the proportional-integral loop. This preliminary limitation prevents the governor's PI loop from over-compensating during cloud passage, thereby preventing power overshoot after the cloud passes while still enabling adequate power generation recovery
3Power
If controllers limit active power but not current, then power output control is improved, but overcurrent protection trips occur during overgeneration
Solution Approach 1:
The invention changes the parameter of control by applying the first error signal (derived from power measurement and reference comparison) and second error signal (from frequency deviation) to a proportional-integral loop with predetermined minimum and maximum power error limits. This dual-parameter control with limiting ensures that both active power and current are controlled within safe boundaries, preventing overcurrent protection trips while maintaining effective power output control during overgeneration conditions
Data Source
AI summary
A method for controlling power flow between a renewable energy plant and an electric power grid, the plant having an intermittent energy source, the method comprising: using a control system, measuring power output from the plant and determining a first difference between the measured power output from the plant and a power reference; measuring frequency deviation of the power output from the plant and determining a second difference between the measured frequency deviation and a frequency deviation reference; generating a first error by limiting a sum of the first and second differences between predetermined minimum and maximum power error limits; modelling power output from the source and determining a second error between the modelled power output from the source and a control signal applied to the source to control the power output therefrom; and, generating the control signal by applying the first and second errors to a PI loop.