电网电压不对称跌落下直驱风电系统控制策略

Control strategy for direct-drive wind power system under asymmetric grid voltage sag

针对电网电压不对称跌落下直驱风电系统并网运行过程中出现的直流环节过电压、并网电流畸变、并网功率波动问题,在直驱风电系统并网变换器的直流环节并联超导磁储能系统;同时在分析电网电压不对称跌落下网侧变换器数学模型的基础上,采用抑制并网功率波动的正负序电流控制对网侧变换器的控制策略加以改进,从而稳定直流环节电压、改善并网电流品质、抑制并网功率波动。仿真结果验证了该控制策略的正确性和有效性。

In view of problems of DC side overvoltage, grid-connected current distortion and grid- connected power fluctuation existed in grid-connected operation of direct-drive wind power system under asymmetric grid voltage sag, superconducting magnetic energy storage was connected in parallel at DC side of grid-connected converter. Meanwhile, positive and negative sequence current control to suppress the grid-connected power fluctuation was used to improve control strategy for grid side converter based on analysis of mathematical model of the grid side converter under asymmetric grid voltage sag, so as to stabilize DC side voltage, improve grid-connected current quality and suppress grid-connected power fluctuation. The simulation result verifies correctness and effectiveness of the control strategy.