【摘要】 为满足光伏逆变器并网要求,针对电网电压在对称跌落和不对称跌落情况,分别采用不同的低电压穿越控制策略。当发生对称跌落时,封锁电压外环,电流内环给定指定值;当发生不对称跌落时,采用电压前馈算法有效抑制跌落瞬间的电流冲击;快速的正负序分量提取和精确的电网电压同步信号,保证控制信号提取的实时性;抑制负序电流分量,保持三相电流平衡并动态调节无功电流输出,满足无功支撑要求;有源阻尼控制将保证系统的稳定运行。基于10 k W三电平光伏并网逆变器,进行Matlab/Simulink仿真和现场实验。结果表明,控制策略能有效抑制并网电流的瞬间冲击并具有较高的正弦度,从而保证在电网发生跌落期间的安全穿越。更多还原

【Abstract】 In order to meet the grid-connected technical specification of photovoltaic(PV)inverter,a control strategybased on three-phase grid-connected voltage symmetrical and unsymmetrical sags for low voltage ride through(LVRT)was proposed. The voltage outer-loop was blocked and the current inner-loop of the specified value was given when threephase symmetrical voltage sag. The grid- connected voltage feed- forward control was adopted to suppress the currentimpact at the moment of voltage sags. Combining with fast extraction of positive- sequence and negative- sequencecomponents of current and accurate synchronization signal of grid-connected voltage to ensure real-time control of theacquired signal,and take maintaining the balance among three-phase currents by suppressing negative-sequence currentcomponent,and adjust reactive current output to meet the reactive power support requirements. Finally,Matlab/simulinksimulation and field experiments were completed based on 10 k W grid-connected PV inverter,the results showed thatthe control strategy can effectively suppress the grid-connected current impact at the moment of voltage sags,and keep ahigh degree of sinusoidal current,which could be achieving security ride through during voltage sags.更多还原