Wind Turbine Grid Frequency Stabilization via PID Control
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Solution Overview
Problem
Wind energy systems face challenges in stabilizing grid frequency due to fluctuations, leading to potential oscillations and instability when reconnecting to the grid, and existing control methods are insufficient to bring the frequency back to nominal levels.
Innovation Solution
Implementing a method that uses a PID controller to actively adjust the active power injection from wind power installations based on actual network frequency deviations, incorporating proportional, integral, and derivative components to stabilize the grid frequency and prevent oscillations by setting specific threshold values for power injection and disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wind power installation reconnects to the grid immediately when frequency returns to nominal range, then the installation can resume power injection quickly, but this may cause frequency oscillations and instability
Solution Approach 1:
The controller implements a frequency threshold mechanism that requires the frequency to remain within the nominal range for a predetermined time period before allowing reconnection. This preliminary waiting action prevents immediate reconnection that could cause oscillations, while still enabling relatively quick resumption of power injection once the stability condition is met.
2Stability of the object's composition
If wind power installation actively adjusts power injection to bring frequency back to nominal levels, then grid frequency stability is improved, but this requires more complex control mechanisms
Solution Approach 1:
The controller continuously monitors the actual grid frequency and uses this feedback to dynamically adjust the active power injection from the wind power installation. When frequency deviates from nominal, the controller modifies power injection levels to help restore frequency to nominal range, creating a closed-loop feedback control system that actively stabilizes the grid.
3Reliability
If multiple wind power installations disconnect simultaneously when frequency exceeds limits, then individual installation protection is achieved, but this creates oscillating disconnection-reconnection loops
Solution Approach 1:
The controller implements a preventive mechanism that monitors frequency trends and implements control actions before oscillating disconnection-reconnection loops can develop. By requiring frequency to remain stable within nominal range for a predetermined time before reconnection, the system preemptively prevents the conditions that would lead to oscillatory behavior, rather than merely reacting to frequency excursions.
Data Source
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AI summary
The purpose of the invention is to reduce the contribution of wind power installations to frequency errors on the grid, and preferably to contribute to the elimination of such errors. Thus, the method involves the use of PID control and/or control with hysteresis so as to regulate the active power injected into the grid, in view of the deviation between a measured grid frequency and the nominal grid frequency.