光储并网发电系统低电压穿越控制策略

Low-voltage Ride-through Control Strategy for Grid-connected Photovoltaic Power Generation System

  • 摘要: 根据电网故障条件下的新能源并网发电系统的低电压穿越的要求,以抑制负序电流为控制目标建立αβ坐标系下的两级式光储并网发电系统的控制模型.前级光伏系统采用基于电压分层的变功率轨迹跟踪控制策略,保证电压跌落期间直流母线电压和光伏系统输出功率的稳定.后级并网逆变器采用基于电压前馈的准比例谐振双环控制策略,实现频率偏移条件下控制系统的稳定,增强系统抗扰动能力.故障期间采用无功优先的控制策略来支撑电网电压的恢复,通过改进的锁相环模块进行复杂工况下电网电压信号的同步,根据跌落深度的不同来控制逆变器发出无功功率的大小.在Matlab/Simulink中搭建不对称的故障工况下的光伏并网发电系统的仿真模型并进行测试,验证了所提方法的有效性.

     

    Abstract: Based on the requirement of low voltage ride-through capability of the new energy grid-connected power generation system under grid fault conditions, taking suppressing the negative sequence current as the control target, the control model of the two-stage optical storage grid-connected power generation system under the αβ coordinate system is established. The pre-stage photovoltaic system adopts a variable power trajectory tracking control strategy based on layered voltage to ensure the stability of the DC bus voltage and the output power of the photovoltaic system during fault crossing. Simultaneously, the stability of the system under frequency offset conditions and system's anti-disturbance capability can be enhanced by using a control strategy with grid voltage feed forward for double closed-loop quasi-proportional resonance strategy on the post-stage grid-connected inverter. The reactive power priority control strategy is used to support the recovery of the grid voltage during the fault by using the improved phase-locked loop module, this module can Synchronization of grid voltage signals under complex conditions and control the magnitude of the reactive power generated by the inverters. Finally, simulation module is built in Matlab/simulink under the fault conditions of frequency offset, phase jump and voltage asymmetry to verify the effectiveness of the proposed method.

     

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