不对称电压跌落下逆变电源的多目标控制策略

Multi-Objective Control Strategies of Grid Interface Inverter under Unbalanced Voltage Sags

当电网发生不对称电压跌落时,需要对分布式逆变电源进行故障下的穿越控制,保证其能够继续向电网输送功率而不退出运行。提出一种新型的适用于分布式逆变电源接口逆变器的多目标控制策略,旨在满足多样化的故障穿越需求。首先,提出并推导一种新型的统一电流参考计算表达式,通过引入参数k_1和k_2来实现对多个目标的控制。然后,推导一种最优波动功率幅值的搜索路径用来实现对参数k_1和k_2的优化选择。通过简化最优搜索路径,得到了另一种线性的搜索路径,该路径可以近似代替优化路径并削减控制的复杂度。接着,根据控制目标在搜索路径上的单调性,设计了一种定功率波动幅值以及自适应的电流不平衡度限制的控制策略。最后,通过仿真算例验证了所提控制策略的有效性和灵活性。

The grid interface inverters of distribution generation should realize low-voltage ride-through property to deliver power to the grid under unbalanced voltage sags. In this paper, a novel multi-objective control strategy is proposed for grid-interface inverters to meet diverse ride-through requirements during gird faults. First, a unified formula for the current reference is established and multiple targets can be controlled by the adjustable parameters kx and k2. Next, an optimized search path for kx and k2 is derived to control the oscillating power of the inverter. Moreover, a linear search path which can replace the optimized one is obtained by simplifying the optimized path. Then, according to the monotonous property of the controlling objective, a novel multi-objective control scheme is proposed with adaptive limitation for the current unbalanced factor. Finally, the effectiveness and flexibility of the proposed control strategies are verified by simulation results.