Hybrid Wind Generator DFIG Synchronous Stability
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Solution Overview
Problem
Current wind turbines using single generators are limited by the characteristics of that generator, restricting performance and efficiency, and lack redundancy and cost-effectiveness, especially in variable wind conditions and remote areas.
Innovation Solution
A hybrid power-generating device integrating a doubly-fed induction generator (DFIG) as the primary generator and a synchronous generator (SG) as the auxiliary generator, with the SG's rated power no larger than one third of the DFIG, allowing for enhanced performance, stability, and reduced operating costs, while enabling operation at low wind speeds and independent grid connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single generator is used in wind turbines, then the device complexity is reduced, but the performance and efficiency are restricted
Solution Approach 1:
The patent combines two different types of generators (DFIG and SG) into a hybrid power-generating system. The DFIG handles variable speed operation and grid synchronization, while the SG provides stable power output and voltage support. This merging allows the system to leverage the strengths of both generator types, improving overall energy production efficiency while maintaining manageable complexity through coordinated control.
Solution Approach 2:
The hybrid system performs multiple functions simultaneously: the DFIG provides variable speed control and maximum power point tracking, while the SG provides voltage stabilization and grid support. This multi-functionality allows a single generator system to handle diverse operational requirements, improving productivity without proportionally increasing complexity.
2Ease of manufacture
If a DFIG is used as the primary generator, then the operating cost is reduced through partial power converter, but the grid stability and performance are compromised during voltage dips
Solution Approach 1:
The SG is pre-configured in the hybrid system specifically to provide voltage support and reactive power during grid faults. When voltage dips occur, the SG immediately activates to stabilize the grid, cushioning the impact that would otherwise cause the DFIG to disconnect. This prior cushioning capability maintains reliability while the DFIG continues to provide cost-effective partial power conversion operation.
Solution Approach 2:
The SG acts as an intermediary between the DFIG and the electrical grid during fault conditions. It absorbs the grid instability and protects the DFIG from direct exposure to voltage dips, allowing the DFIG to maintain its cost-effective operation while the SG handles the reliability-critical grid interaction during disturbances.
3Reliability
If the SG rated power is increased to provide sufficient auxiliary power, then the redundancy and reliability are improved, but the operating cost increases significantly
Solution Approach 1:
The SG is designed with partial action principle - its rated power is set to no larger than one third of the DFIG rated power. This partial sizing is sufficient to provide the necessary auxiliary functions (voltage support, reactive power, startup assistance) without over-provisioning. The SG operates at elevated load ratios when active, providing adequate reliability and redundancy while controlling manufacturing and operating costs.
4Ease of manufacture
If a fixed speed induction generator is used, then the device reliability is improved and cost is reduced, but the wind energy conversion efficiency is suboptimal and reactive power support is required
Solution Approach 1:
The DFIG component enables variable speed operation, allowing the rotor to rotate at different speeds according to wind conditions. This dynamic operation optimizes the tip-speed ratio and maximizes aerodynamic efficiency across varying wind speeds, significantly improving wind energy conversion efficiency compared to fixed-speed operation, while the partial power converter keeps costs manageable.
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
The hybrid system improves overall performance and grid stability, reduces energy production costs, and allows for independent operation in remote areas by leveraging the strengths of both generator types, with the SG providing additional power and redundancy without significant cost increases.
Implementation Method 1
a primary electrical generator, being specifically a doubly-fed induction generator (DFIG)
Implementation Method 2
an auxiliary electrical generator, being specifically a synchronous generator (SG)
Data Source
AI summary
The present invention relates to a hybrid power-generating device and a power generating method thereof. The hybrid power-generating device is primarily comprised of: a primary electrical generator and an auxiliary electrical generator with different characteristics, both mechanically coupled to a prime while enabling the rated power of the auxiliary electrical generator to be smaller than that of the primary electrical generator; wherein, as the prime is operating at a low rotation speed or at its initial operating stage, the auxiliary electrical generator is enabled to be driven and activated thereby; and as the operating speed of the driver is stabilized and reaches a predetermined value, the primary electrical generator is then being driven and activated thereby. By the aforesaid hybrid power-generating device, not only the overall performance and the stability of power grid are enhanced, but also the operating cost is reduced.