Wind Turbine Overvoltage Ride-Through via AC Load Dump
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Solution Overview
Problem
Wind turbines face challenges in handling overvoltage events, which can lead to equipment damage and disconnection from power grids, especially in offshore wind farms, due to the stress on insulation systems and sensitive power electronics.
Innovation Solution
A method involving a wind turbine system with a power generator, machine side and line side converters, and a DC-link, where active operation is disabled during overvoltage events, and an AC-load dump is enabled to dissipate power, with a waiting period before resuming operation, ensuring safe and stable transition back to normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main-circuit breaker trips during an overvoltage event, then the wind farm is protected from severe damage, but the wind farm is left in isolated operation with the cable and transformer experiencing continued overvoltage stress
Solution Approach 1:
The control system activates the AC-load dump resistor before the overvoltage becomes severe, preparing the dissipation path in advance. When overvoltage is detected, the system has already positioned the resistor to absorb excess energy, preventing the need for breaker tripping and avoiding isolated operation with continued stress on insulation systems.
Solution Approach 2:
The invention converts the harmful overvoltage energy into useful heat dissipation through the AC-load dump resistor. By providing a controlled path for excess energy dissipation, the system transforms the damaging overvoltage condition into a manageable thermal process, protecting insulation systems while maintaining grid connection.
2Reliability
If the wind turbine disables active operation of converters during overvoltage, then equipment is protected from damage, but power transfer to the grid is interrupted
Solution Approach 1:
The AC-load dump resistor serves as an intermediary element that absorbs excess power from the generator during overvoltage events. This mediator allows the system to protect converters from damage while providing a controlled path for energy dissipation, enabling the wind turbine to ride through the event without complete power transfer interruption.
Solution Approach 2:
The system changes the operational parameters of the AC-load dump resistor, switching it from a high-impedance state during normal operation to a low-impedance state during overvoltage events. This parameter change enables the resistor to absorb excess power when needed while minimizing its impact on normal power transfer, balancing equipment protection with productivity.
3Reliability
If the wind turbine implements overvoltage protection measures, then ride through capability is achieved, but hardware and software complexity increases
Solution Approach 1:
The AC-load dump resistor is designed to serve multiple functions: it provides overvoltage protection, enables ride through capability, and can be integrated with existing converter systems. By making this single component multi-functional, the invention achieves comprehensive protection without proportionally increasing overall system complexity.
Solution Approach 2:
The control system automatically detects overvoltage conditions and activates the AC-load dump resistor without requiring external intervention or complex coordination with other systems. The system monitors its own state and self-regulates to provide protection, reducing the need for additional complex control infrastructure while achieving reliable ride through capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows wind turbines to effectively ride through overvoltage events without damaging equipment, maintaining grid connection and ensuring smooth power transfer, with minimal hardware and software changes, and is robust enough to handle both symmetric and asymmetric overvoltages.
Implementation Method 1
an AC-load dump connected between the machine side converter and the power generator is enabled in order to dissipate power output from the power generator into the AC-load dump
Data Source
AI summary
A method of operating a wind turbine is disclosed, the wind turbine comprising a power generator, a machine-side converter connected to the power generator, a line-side converter connected to a power grid through associated power components, and a DC-link connected between the machine-side converter and the line-side converter. The method includes monitoring the power grid for overvoltage events, and upon detecting an overvoltage event: (1) disabling active operation of the machine-side converter and the line-side converter, (2) enabling an AC load dump connected between the machine side converter and the power generator in order to dissipate power output from the power generator, (3) waiting for a waiting period, and (4) enabling active operation of the line-side converter and the machine converter when the overvoltage event ends within the waiting period.