Guide Vane Command Limiting for Stable Pumped Storage Speed Control
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Solution Overview
Problem
In conventional power generation and pumped storage power generation systems, the guide vane opening degree command value held in the integral control element can lead to excessive closure and subsequent re-opening of the guide vane during load breaking, causing rotational speed fluctuations and instability.
Innovation Solution
A method is introduced that includes a rotational speed controller with a modified output runaway prevention circuit and a load limiter, which limits the guide vane opening degree command and restricts excessive closing, thereby preventing the guide vane from re-opening excessively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gain of the integral control element is increased to prevent excessive guide vane opening during load breaking, then the guide vane opening degree stability is improved, but the water pressure fluctuation in the conduit becomes excessive
Solution Approach 1:
The patent segments the control function by introducing a separate guide vane opening degree limiter that operates independently from the integral control element. This limiter specifically constrains the guide vane opening degree command value during load breaking conditions, allowing the integral control element to maintain its original gain settings without causing excessive water pressure fluctuations, while still preventing the guide vane from excessively increasing.
Solution Approach 2:
The guide vane opening degree limiter acts as an intermediary between the rotational speed controller and the guide vane operation mechanism. It receives the guide vane opening degree command value from the rotational speed controller and applies appropriate constraints before transmitting it to the guide vane operation mechanism, thereby mediating the conflict between stability and pressure fluctuation.
2Stress or pressure
If the gain of each control element is set small to prevent excessive water pressure fluctuation and ensure smooth power supply change, then the water pressure stability is improved, but the guide vane opening degree response becomes slow causing rotational speed to reach maximum and then fluctuate
Solution Approach 1:
The patent separates the control functions by introducing a dedicated guide vane opening degree limiter that provides fast response constraints independent of the slow-responding integral control element. This allows the control elements to maintain small gains for water pressure stability, while the limiter ensures rapid guide vane opening degree response by directly constraining the command value.
Solution Approach 2:
The guide vane opening degree limiter dynamically adjusts the guide vane opening degree command value based on real-time operational conditions, particularly during load breaking when rotational speed exceeds the rated value. This dynamic constraint provides fast response without requiring increased control element gains.
3Productivity
If the integral control element holds the guide vane opening degree command value corresponding to load output, then the load output control is improved, but the guide vane opening degree excessively increases again after initial closure during load breaking
Solution Approach 1:
The guide vane opening degree limiter applies preliminary anti-action by constraining the guide vane opening degree command value before the integral control element can cause it to excessively increase. During load breaking, when rotational speed exceeds the rated value, the limiter proactively prevents the command value from rising, counteracting the inherent tendency of the integral control element to increase it.
Solution Approach 2:
The system uses feedback from the rotational speed signal to trigger the guide vane opening degree limiter. When the rotational speed exceeds the rated value during load breaking, this feedback activates the limiter to constrain the guide vane opening degree command value, creating a closed-loop protection mechanism that maintains stability while preserving load output control.
Data Source
AI summary
A method of controlling a power generation apparatus and a pumped storage power generation apparatus including a motor directly connected to a rotor of a generator or generator motor, the method performing speed control by providing a guide vane opening degree command to the motor, the guide vane opening degree command being calculated by a rotational speed controller including a proportional control element, an integral control element, and a differential control element, in which a first upper limit limiting function is multiplied by a second upper limit limiting function, the first upper limit limiting function being included in an output runaway prevention circuit of an integral control function provided in the integral control element and being defined according to an output signal of a load limiter.