电网不对称故障下光伏并网逆变器的无功支撑控制策略

REACTIVE POWER SUPPORT CONTROL STRATEGY FOR PV GRID-CONNECTED INVERTERS UNDER ASYMMETRIC GRID FAULTS

针对电网不对称故障下光伏系统存在的输出电流峰值越限、交流侧功率波动、直流侧电压不稳定等问题,该文提出一种电网不对称故障下光伏并网逆变器无功支撑控制策略。以无功支撑要求为目标,以有功功率波动幅值和输出电流峰值为约束条件确定逆变器的有功功率安全运行区域,提供足够无功支撑并扩展有功功率输出能力,或在约束条件内根据无功电流权重提供部分无功支撑,保证光伏系统在发生电网不对称故障时安全运行,最后仿真验证了控制策略的有效性。

Aiming at the problems of output current peak exceeding limit,AC side power fluctuation and DC side voltage instability in photovoltaic system under asymmetric grid fault,this paper proposes a reactive power support control strategy for photovoltaic grid-connected inverter under asymmetric grid fault.Taking the reactive power support requirement as the goal,the active power safe operation area of the inverter is determined with the active power fluctuation amplitude and the output current peak as the constraint conditions,providing sufficient reactive power support and expanding the active power output capability,or providing partial reactive power support according to the reactive current weight within the constraint conditions to ensure the safe operation of the photovoltaic system in the event of an asymmetric grid fault.Finally,the simulation verifies the effectiveness of the control strategy.