CAJ | 학술논문

分析了电网不对称故障下含飞轮储能单元的永磁直驱风电系统直流母线电压波动机理，在此基础上，研究了适用于该类型风电系统低电压穿越增强运行控制策略。所提控制策略在实现电网不对称故障下发电系统向电网提供暂态无功支持的同时，亦可提供3种可选的独立运行模式。所提控制方案突破传统控制模式下网侧变换器抑制直流链电压波动能力的局限，将比例积分谐振控制器(proportional integral resonant，PIR)引入飞轮电机电流闭环控制，利用飞轮储能单元吸收直流电容2倍工频脉动功率，从而有效实现故障过程中直流链电压的稳定无波动控制，进一步增强系统不对称故障穿越运行能力。通过仿真计算验证了所提控制策略的正确性和有效性。
분석료전망불대칭고장하함비륜저능단원적영자직구풍전계통직류모선전압파동궤리，재차기출상，연구료괄용우해류형풍전계통저전압천월증강운행공제책략。소제공제책략재실현전망불대칭고장하발전계통향전망제공잠태무공지지적동시，역가제공3충가선적독립운행모식。소제공제방안돌파전통공제모식하망측변환기억제직류련전압파동능력적국한，장비례적분해진공제기(proportional integral resonant，PIR)인입비륜전궤전류폐배공제，이용비륜저능단원흡수직류전용2배공빈맥동공솔，종이유효실현고장과정중직류련전압적은정무파동공제，진일보증강계통불대칭고장천월운행능력。통과방진계산험증료소제공제책략적정학성화유효성。
The mechanism of DC bus voltage fluctuation in permanent magnet direct-drive wind power system containing flywheel energy storage unit during asymmetrical fault in power grid is analyzed, and on this basis an enhanced control strategy suitable to low-voltage ride through (LVRT) in such a wind power system is researched. Three selectable independent operating modes can be provided when the wind power system provides power grid transient reactive power support during asymmetrical fault in power grid by the proposed control strategy. The proposed control scheme surmounts the limitation of restraining DC-link voltage fluctuation by grid-connected converter under traditional control modes and leads proportional integral-resonant (PI-R) controller into closed-loop current control of flywheel motor to absorb double power frequency pulsating power in DC-link capacitor by flywheel energy storage unit, thus the stable control of DC-link voltage free of fluctuation during asymmetrical fault in power grid can be effectively implemented and further enhance LVRT ability of wind power system under asymmetrical fault in power grid. The correctness and effectiveness of the proposed control strategy are verified by Matlab/Simulink-based simulation results.