永磁直驱风电低电压穿越与功率平抑策略研究

Strategy Research on Low Voltage Ride Through and Power Smoothing ofPermanent Magnet Direct Drive Wind Turbines

针对永磁直驱风电机组低电压穿越和功率平抑两种问题,提出采用改进超级电容储能系统(ISCESS)和串联制动电阻(SDBR)的联合控制策略。将ISCESS并联在机组的直流链上,SDBR则串联在电网与并网点之间。当风电并网系统正常运行时,ISCESS凭借快速充放电能力平抑机组的并网功率。当电网故障电压骤降时,SDBR抬升并网点的电压并耗散不平衡能量,另一部分不平衡能量则由ISCESS吸收。研究结果表明,所提策略在正常运行时能有效对永磁直驱风电机组的并网功率进行平抑,在电网故障时能有效提升机组的低电压穿越能力。

In order to solve the two problems of low voltage ride through and power smooth for permanent magnet synchronous generator,the combined control strategy of improved supercapacitor energy storage system(ISCESS)and series dynamic braking resistors(SDBR)is proposed.In this paper,ISCESS is connected in parallel to the DC chain of the unit,and SDBR is connected in series between the grid and the grid connection point.When the wind power grid-connected system is in normal operation,ISCESS smooths the grid-connected power of the unit with its fast charging and discharging capability.When the grid fault voltage suddenly descends,the SDBR raises the voltage of the junction point and dissipates the unbalanced energy,ISCESS absorbs the other part of the unbalanced energy.The results show that the proposed strategy can effectively smooths the grid-connected power of permanent magnet direct drive wind turbines during normal operation,and enhance the low voltage ride through capability of the unit during grid faults.