1. Introduction to Yaw drivers

The yaw system, also known as the wind alignment device, is an important component of the wind turbine nacelle. The yaw system is used to drive the nacelle to rotate around the tower, keeping the wind turbine blades always facing the wind direction to maximize the capture of wind energy. The yaw system is mainly divided into passive yaw and active yaw. The passive yaw system uses wind pressure to generate torque to align the wind turbine with the wind direction. However, it cannot automatically untwist the cables and is prone to cable over-twisting faults, so it is rarely used. The active yaw system uses electricity or hydraulics to drive the wind turbine to face the wind.

The active yaw system consists of a yaw bearing, a yaw drive device, a yaw brake, a yaw counter, a cable untwisting protection device, and a yaw hydraulic circuit, etc. By achieving real-time monitoring of the main wind direction changes, automatically adjusting the azimuth angle of the nacelle, ensuring the continuous alignment of the generator set with the wind, and preventing excessive cable twisting, among other multi-functional collaborative operations, it enhances the utilization rate of wind energy, reduces the vibration and noise of the wind turbine, guarantees the efficient and stable operation of the wind turbine unit, improves operational safety, and extends the service life of the wind turbine.

Traditional electric drive scheme

The direct starting method of the yaw motor is convenient to operate and control, simple to maintain, and relatively economical. However, it also has disadvantages such as large starting current impact, large torque fluctuations on yaw bearings, braking and protection devices, and unbalanced load distribution. Motor straight up, starting protector easy trip, will lead to the yaw system outage, wind turbines can't to the wind, thereby causing loss to the power.

Secondly, the large starting impact will cause significant mechanical wear, making it more likely for the yaw bearing to crack or break its teeth. If one of the motors malfunctions or gets damaged, the rest of the motors will no longer be able to operate normally, and the yaw system will completely stop working.

2. FGI Solution

(1）Flexible yawing scheme

To address the issues of the traditional direct start-up scheme, the variable frequency drive scheme provided by FGI adds a variable frequency inverter for soft start-up in the yawing system. Through the interaction of the control logic with the main control system and the effective coordination with the hydraulic control, this scheme significantly improves the operational stability of the yawing system.

The new flexible yawing scheme can reduce the current and mechanical shock during the motor startup process, decrease the occurrence of overload conditions during the yawing of the wind turbine, extend the service life of the yawing motor and bearings, improve the accuracy of the yawing system by precisely identifying the wind direction and the azimuth angle of the nacelle, and achieve better control effect on the angle of the wind turbine nacelle.

In the scheme, the variable frequency system can conduct real-time data interaction with the main control system through industrial communication. The main control system will transfer the data of the frequency converter to the SCADA, HMI interface and data generation records, which can simplify the troubleshooting process and make subsequent maintenance more convenient.

(2) System Architecture and Features

The FGI FD300 series yaw drive frequency converter was selected to achieve flexible start-stop control for multiple yaw motors. The original yaw system control method remained unchanged. The original main control system's manual/automatic mode for yaw control and the flexible yaw mode were retained, and a one-click switching function was also enabled.

3.Application case

The FGI FD300 yaw drive frequency converter, with its advanced space vector control technology, can achieve load balancing within the yaw motor unit. The optimized flexible control algorithm can reduce the occurrence probability of slippage under strong wind conditions, minimize abnormal shutdowns, and improve the wear of bearings and braking systems in the yaw system, significantly lowering mechanical maintenance costs.