不对称故障下两级式光伏并网系统低电压穿越控制  

Low-voltage Riding-through Control Strategy for Two-staged Grid-connected Photovoltaic System Under Asymmetrical Faults

作　　者：王诗雯 刘飞[1] 刘沁怡 庄一展 黄艳辉 查晓明[1] WANG Shiwen;LIU Fei;LIU Qinyi;ZHUANG Yizhan;HUANG Yanhui;ZHA Xiaoming(School of Electrical Engineering and Automation,Wuhan University,Wuhan 430072,Hubei Province,China)

机构地区：[1]武汉大学电气与自动化学院,湖北省武汉市430072

出　　处：《电网技术》2023年第1期91-99,共9页Power System Technology

摘　　要：并网逆变器在传统低电压穿越控制中存在有功功率指令不明确,易受直流电压外环控制参数影响的问题。此外两级式光伏并网系统中前级DC-DC变换器根据直流母线电压波动情况被动调整光伏输出功率,导致光伏侧动态响应速度较慢。提出了一种结合超级电容的两级式光伏并网系统不对称故障低电压穿越控制策略,该策略重点关注低电压穿越期间光伏侧的输出特性,可根据逆变器的输出能力计算其可输出的最大有功功率,利用直流母线两端的超级电容变换器稳定母线电压,光伏升压变换器用于控制光伏功率出力以快速与逆变器有功功率出力匹配。仿真结果表明,在不对称故障下,所提方法可在稳定直流母线电压的同时,实现光伏侧输出功率的快速调节。In the existing low-voltage ride-through(LVRT)control strategies, the power command, affected by the control parameters, does not have a definite value. Besides, the front-end DC-DC converter passively adjusts the output power of photovoltaic(PV) array according to the variation of DC bus voltage, so that the dynamic response of the PV side is relatively low. This paper proposes a LVRT control strategy under an asymmetrical fault for the two-staged grid-connected PV system based on the super-capacitor(SC). The proposed method mainly focuses on the dynamic response of the PV side,which can calculate the maximum output active power of the inverter according to its capacity. The SC converters at the both ends of the DC bus are used to stabilize the DC bus voltage,and the boost converter at the PV side is used for controlling the PV output power in order to match the output active power of the inverter quickly. The simulation results show that under the asymmetrical fault, the proposed method is able to stabilize the DC bus voltage and realize the rapid adjustment of the PV output power.

关 键 词：两级式光伏并网系统 不对称故障 低电压穿越 超级电容 有功指令共享 

分 类 号：TM721[电气工程—电力系统及自动化]