网端负载波动时混合传动风电系统的控制方法

The Control Strategy of Hybrid Drive Wind Power Generation System During Load Fluctuation in the Grid

由于目前采用电力电子变流设备来实现变速恒频的风电机组具有成本高、低电压穿越能力弱、可靠性差等缺点,一种利用混合传动系统进行调速,实现变速恒频的方法成为研究热点。但该新型调速系统存在由于网端负载波动而影响调速电机控制精度的问题。针对此问题,对于该变速恒频风电系统中的调速电机提出了一种包含转矩观测器和线性二次控制器的转速控制新方法。利用岭回归算法,估算了调速系统的转动惯量和阻尼系数等参数。通过试验验证,证明了在网端负载波动和变风速的运行条件下,负载转矩观测器能有效的跟踪网端负载的变化。基于负载观测器所设计的调速电机控制方法不仅能使得调速系统输出误差满足实际应用要求,并且使其对于网端负载波动具有较强的稳定性。

As a result of these shortcomings such as high cost, weak ability of low voltage ride through and poor reliability, when adopting frequency converters to get power with constant frequency in wind turbines, a kind of speed regulating method by using hybrid drive system to achieve variable speed constant frequency is becoming the hot area of research. However, the hybrid drive system is subject to the pulsating torque because of load fluctuation in the grid, which can seriously affect the accuracy of speed control of the speed regulating motor. Owing to these problems, a new control strategy composed by the linear quadratic controller and load torque observer for speed regulating motor was proposed. In addition, the related parameters including rotational inertia and viscous friction coefficient of the speed regulating system were calculated accurately via ridge regression algorithm. At last, we verified that the observer can observe the change of load torque rapidly under the operating conditions of chang＇rag wind and fluetuant load. Experimental results show that the control precision for output speed by using the designed controller can meet the praetieal requirements. In addition, the system has great stability during load fluctuation in the grid.