Wind Power Reactive Power Controller Grid Stability

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Solution Overview

Problem

Existing wind power generation systems face challenges in maintaining grid stability during transient conditions, particularly avoiding voltage collapse that may necessitate disconnection from the grid, due to inadequate control of reactive power feeding.

Innovation Solution

A method involving determining the Q-V characteristic of the grid at the point of connection and controlling reactive power feeding based on this characteristic to prevent voltage collapse, by maintaining reactive current above a safe minimum level, thereby enhancing system reliability and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If reactive power is fed to the grid during transient conditions, then grid stability is improved, but voltage collapse may occur causing system disconnection

Engineering Contradiction:
Improvegrid stabilityVSAvoidvoltage collapse
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system determines the Q-V characteristic of the grid and uses this feedback information to control reactive power feeding. The controller continuously monitors the relationship between reactive power (Q) and voltage (V) and adjusts reactive power injection accordingly to maintain voltage within safe operating limits, preventing voltage collapse while maximizing grid stability support.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system changes the operating parameters by determining the Q-V characteristic curve and identifying the nose point (maximum reactive power point). By operating below this nose point and maintaining a safety margin, the system dynamically adjusts reactive power levels based on grid conditions, transforming the control approach from fixed to adaptive parameter management.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If reactive power is controlled to prevent voltage collapse, then system reliability is improved, but control complexity increases

Engineering Contradiction:
Improvesystem reliabilityVSAvoidcontrol complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system performs preliminary determination of the Q-V characteristic and nose point before actual transient events occur. This advance characterization of the grid's voltage-reactive power relationship allows the controller to pre-establish safe operating boundaries, simplifying real-time control decisions during actual transients by referencing pre-computed safety margins.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the nose point is determined and minimum reactive current is established, then operating safety is improved, but measurement and control difficulty increases

Engineering Contradiction:
Improveoperating safetyVSAvoidnose point detection
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The system determines the Q-V characteristic at regular intervals through periodic disturbance injection, rather than waiting for natural grid disturbances. This scheduled periodic measurement ensures the nose point and safety margins are continuously updated without requiring complex real-time detection algorithms, balancing measurement accuracy with operational simplicity.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentEP2376773B1Control method and apparatus
Publication Date: 2016.06.15 VESTAS WIND SYSTEMS AS
  • EP2376773B1 patent drawingFigure 1~2
  • EP2376773B1 patent drawingFigure 3
  • EP2376773B1 patent drawingFigure 4~6

AI summary

The present disclosure relates to method and a controller for controlling a wind power generation system. The system is connected to a grid at a point of connection, and is devised to feed reactive power to the grid in order to improve grid stability. A Q-V characteristic is determined for the grid at the point of connection as well as a nose point for the Q-V characteristic. A minimum reactive current, lQmm, which is safe from the nose point, is determined, and the feeding of reactive power is controlled such that the reactive current is kept higher than the minimum reactive current. In this way it is made sure that the reactive current does not make the Q-V characteristic reverse, and thereby the stability of the system is improved.