低电压穿越(Low-Voltage Ride Through，LVRT)是影响光伏并网发电系统稳定运行的重要因素。针对这一现状，文中提出了一种混合储能（Hybrid Energy Storage System，HESS）的控制策略来解决，HESS由蓄电池储能系统（Battery Energy Storage System，BESS）和超导磁储能系统 (Superconducting Magnetic Energy Storage，SMES) 构成。采用低通滤波的方法将不平衡功率分频，为HESS分配功率指令。当光伏并网发电系统正常运行时，HESS用于平抑功率波动。当出现短路故障时，采用无功电流注入的策略使光伏逆变器发出无功功率，此时不平衡功率仅由SMES吸收，BESS不参与运行。通过SMES与光伏逆变器的配合，顺利实现LVRT过程。所提方法能够提高光伏发电系统的低电压穿越能力，减小功率波动对电网的冲击，有一定的实际应用价值。
英文摘要:
Low-voltage ride through (LVRT) is an important factor affecting the stable operation of photovoltaic (PV) grid-connected power generation system. In view of this situation, a hybrid energy storage system (HESS) control strategy is proposed to solve this problem in this paper. HESS consists of battery energy storage system (BESS) and superconducting magnetic energy storage (SMES). The unbalanced power is divided into frequency by using low-pass filter, and the power command is assigned to the HESS. When the PV grid-connected power generation system operates stably, HESS is used to stabilize the power fluctuation. In case of short-circuit fault, the strategy of reactive current injection is adopted to make the PV inverter generate reactive power. The unbalanced power is only absorbed by SMES during the LVRT, and BESS does not participate in the operation. The LVRT process can be realized successfully by the cooperation of SMES and PV inverter. The proposed method can improve the LVRT capability of PV power generation system and reduce the impact of power fluctuation to power grid, which has certain practical application value.