Wind Turbine Plant Fault Current Control for Circuit Breaker Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wind turbine plants connected to weak grids face challenges during low voltage fault events, where the fault current contribution can exceed the breaking capacity of circuit breakers, leading to potential permanent damage and increased costs due to the need for higher-rated circuit breakers or costly hardware solutions.
Innovation Solution
A method is implemented to monitor the electrical grid for low voltage faults, calculate the grid short circuit strength, determine a short circuit current limit, and operate wind turbine generators to provide a maximum fault current contribution based on this limit, thereby reducing the risk of exceeding circuit breaker capacity while maintaining reactive current support for grid recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wind turbine generators provide large fault current contribution during low voltage faults, then system stability is improved, but circuit breaker breaking capacity is exceeded causing potential damage
Solution Approach 1:
The wind turbine generators dynamically adjust their fault current contribution based on real-time grid conditions and circuit breaker capacity. The control system modulates the active and reactive power output of each generator during fault conditions, transitioning from static current contribution to dynamic control that responds to changing fault severity and grid state, thereby maintaining system stability while preventing circuit breaker overload.
Solution Approach 2:
The invention changes the operational parameters of wind turbine generators during fault conditions by calculating optimal active and reactive power references. The control system adjusts power output parameters based on grid frequency, voltage conditions, and circuit breaker breaking capacity, transforming fixed parameter operation into adaptive parameter control that resolves the contradiction between providing sufficient fault current and protecting circuit breakers.
2Power
If additional power production units are added to the transmission circuit, then power generation capacity is increased, but fault current contribution increases causing further stress on circuit breaker
Solution Approach 1:
Each power production unit (wind turbine generator or appended generator) is equipped with dynamic control capabilities that adjust its fault current contribution in real-time. During fault conditions, the control system continuously monitors grid state and modulates the active and reactive power output of each unit, transforming static power contribution into dynamic control that prevents cumulative fault current from exceeding circuit breaker capacity while maintaining overall power generation capacity.
Solution Approach 2:
The invention implements parameter changes by calculating optimal active and reactive power references for each power production unit based on circuit breaker breaking capacity and grid conditions. The control system adjusts operational parameters (power output, current contribution) of each unit dynamically, allowing multiple generators to operate at full capacity during normal conditions while automatically coordinating their fault current contribution to stay within circuit breaker limits during faults.
3Reliability
If circuit breaker breaking capacity is increased to handle fault current, then system reliability is improved, but hardware cost and complexity increases
Solution Approach 1:
The control system implements continuous feedback monitoring of grid frequency, voltage, and fault conditions, combined with knowledge of circuit breaker breaking capacity. During fault events, the system receives feedback on actual grid state and adjusts the active and reactive power references of wind turbine generators in real-time, creating a closed-loop control system that dynamically ensures fault current contribution remains within circuit breaker capacity without requiring higher-rated hardware.
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
A method of operating a wind turbine plant is provided. Such a wind turbine plant comprises at least one transmission branch comprising a plurality of wind turbine generators and coupled to an electrical grid at a point of common coupling through at least one circuit breaker comprising a breaking capacity. The method comprises monitoring the electrical grid for a low voltage fault event; and if a low voltage fault event is detected: calculating a grid short circuit strength, determining a short circuit current limit if the grid short circuit strength requires an initial fault current contribution which exceeds the breaking capacity of the circuit breaker to be passed through the circuit breaker, determining a maximum fault current contribution based on the short circuit current limit and operating the wind turbine generators to provide to the electrical grid the maximum fault current contribution.