由于新能源并网变流器耐流能力不足，在电网发生故障时容易出现大规模脱网，造成新能源电力系统低电压穿越(LVRT)能力下降，进而危及电力系统的稳定运行。提出一种新能源同步电机对(MGP)系统用于提升新能源发电系统LVRT能力。首先给出了MGP系统的数学模型和控制方法，然后从机械运动方程入手分析MGP系统的故障隔离机理，并对直流电压反馈控制在电压跌落过程中的调控机理进行了详细阐述。进一步以光伏(PV)发电系统为例，通过仿真分析了采用MGP系统对低电压穿越能力的提升及无功支撑作用。最后对所提并网方案的低电压穿越效果进行试验研究，验证了光伏逆变器采用直流电压反馈控制后MGP系统可以有效提高光伏低电压穿越能力。

Due to the insufficient current withstanding capacity, the grid-connection converter of the new energy unit is easy to cause large-scale off grid in case of grid failure, which will lower the low voltage ride-through (LVRT) capability of the new energy system and endanger the stable operation of the power system. A motor-generator pair (MGP) system is proposed to improve the LVRT capability of the new energy generation system. Firstly, the mathematical model and control method of the MGP system are given. Then the fault isolation mechanism is analyzed from the mechanical motion equation, and the regulation mechanism of the DC voltage feedback control in the process of voltage drop is illustrated in detail. Taking the photovoltaic (PV) generation system as an example, the simulation model is built to verify the LVRT capability and reactive power support by adopting the MGP system. Finally, experimental validation on the LVRT effect is performed, and the results show that the MGP system can effectively improve the LVRT capability of PV inverter with DC voltage feedback control.

贵州电网公司科技项目(067600KK52180007)