基于光伏系统低电压穿越的无功控制策略

Strategy for Reactive Control Based on Ability of Low Voltage Ride Through in Photovoltaic Power System

分析了光伏逆变器的结构和功率控制方式。计算了光伏逆变器的无功功率极限。提出了一种基于光伏逆变器低电压穿越(LVRT)能力的无功控制策略。通过DIgSILENT PowerFactory仿真结果表明,采用该控制策略的光伏电站,可以在电网故障时不脱网并发送无功,支撑并网点电压,维持局部电网电压稳定。

Photovohaic （PV） power station is usually running under condition of unity power factor to output active power as nmch as possible or in accordance with dispatch. And it outputs almost no reactive power which results in a certain extent waste of apparent power when PV power station is not running at full power. However, The PV inverter has reactive power output capacity. A strategy for reactive power control based on inverter＇ s low voltage ride through （LVRT） ability is proposed on conditional that PV inverter＇ s structure and power control mode were analyzed. The limit of reactive power output was calculated. The results of DIgSILENT PowerFactory simulation show that the proposed strategy can make PV power station connected to the grid when faults happen and send reactive power to support voltage of PCC, result in the voltage stability of local grid.