Wind power generation selection guide: how to choose the most suitable generator?
The core of wind power generation is to efficiently and reliably convert wind energy into electrical energy, and the choice of generator directly affects system performance and cost. The current mainstream types of wind turbines include asynchronous generators, doubly fed induction generators, and permanent magnet synchronous generators, each with their own advantages and disadvantages, which need to be matched according to the application scenario.
1、 Asynchronous Generator: A Low Cost Beginner's Choice
Principle: By generating electricity through electromagnetic induction, the rotor speed is slightly higher than the synchronous speed, and reactive power needs to be absorbed from the power grid.
Advantages:
Simple structure: brushless and slip ring, low maintenance cost, suitable for harsh environments.
Low price: Mature technology, low initial investment.
Disadvantages:
Efficiency is average: excitation losses result in an efficiency of approximately 85% -90%.
Reactive power compensation is required: additional capacitors or compensation devices need to be configured, otherwise it will affect the grid voltage.
Applicable scenarios: Small and medium-sized wind power systems, areas with high grid stability (such as rural distributed wind power).
2、 Double fed Induction Generator (DFIG): Balancing Efficiency and Cost
Principle: The stator is directly connected to the grid, and the rotor is connected to the grid through an inverter to achieve variable speed constant frequency operation.
Advantages:
Variable speed operation: It can efficiently generate electricity within a wind speed range of 3-25m/s, expanding the range of wind energy utilization.
Partial power conversion: Only 25% -30% of the power on the rotor side needs to be processed, and the cost of the converter is low.
Reactive power support: Provide reactive power compensation through inverters to improve grid stability.
Disadvantages:
Complex structure: requires gearbox and slip ring, with a high mechanical failure rate.
Applicable scenarios: Large onshore wind farms, areas with high wind speed fluctuations (such as mountainous areas and coastal regions).
3、 Permanent Magnet Synchronous Generator (PMSG): An Efficient and Low Maintenance Future
Principle: By using permanent magnets to generate a magnetic field, there is no need for external excitation, resulting in higher efficiency.
Advantages:
High efficiency: No excitation loss, efficiency can reach over 95%, especially suitable for low wind speed areas.
Compact structure: Omitting electric brushes and slip rings, low failure rate, and reduced maintenance costs by more than 30%.
Advantages of direct drive: Directly connected to the blades (without gearbox), reducing noise by 10-15 decibels.
Disadvantages:
High cost: The price of permanent magnet materials (such as neodymium iron boron) fluctuates greatly, and the initial investment is high.
Applicable scenarios: offshore wind power, low wind speed inland areas, and noise sensitive environments (such as near residential areas).
4、 How to choose? The key is to focus on these three points
Wind speed conditions:
Low wind speed zone (annual average wind speed<6m/s): Choose a permanent magnet synchronous generator (with higher efficiency).
High wind speed zone: doubly fed generator or asynchronous generator (lower cost).
Grid requirements:
Weak current network may require reactive power support: doubly fed generator (with flexible power factor adjustment).
Strong power grid: Both asynchronous and permanent magnet synchronous generators are suitable.
Cost and maintenance:
Initial budget limited: asynchronous generator (priced 20% -30% lower).
Long term operation and maintenance sensitivity: permanent magnet synchronous generator (reducing maintenance costs by 40% over 10 years).
5、 Trend: Direct drive permanent magnet synchronous generators become mainstream
With technological advancements, direct drive permanent magnet synchronous generators (omitting gearboxes) are becoming the preferred choice for offshore wind power and low wind speed areas. Its advantages include:
Reliability improvement: Reduce mechanical failure points by 50% and extend lifespan to over 25 years.
Efficiency optimization: The full power converter achieves power grid fault ride through (LVRT) and adapts to weak power grids.
Environmental adaptation: low noise, no oil pollution, suitable for marine ecological protection requirements.
case
Danish Vestas V236-15.0 MW offshore wind turbine: using direct drive permanent magnet technology, with an annual power generation of over 80GWh per unit.
China Goldwind Technology GW82-1.8MW onshore wind turbine: permanent magnet direct drive design, can start generating electricity at a wind speed of 3m/s.
Conclusion
The selection of wind turbines requires a balance between efficiency, cost, and reliability. For most projects:
Onshore wind power: doubly fed generator (balance performance and price).
Offshore wind power: direct drive permanent magnet synchronous generator (high reliability, low maintenance).
Distributed wind power: asynchronous generators (low-cost) or permanent magnet synchronous generators (high-efficiency).
With the decrease in the cost of permanent magnet materials and the maturity of direct drive technology, wind power generation will be more efficient, quieter, and sustainable in the future.
