不对称短路故障下多风电场电压控制方法研究

Research on voltage control method of multi-wind farms under grid asymmetric faults

由于风电场往往处在电网末端,与负荷中心呈现逆分布特点,系统在不对称短路故障条件下具有较差的电压支持能力,风电机组的低电压运行适应性能受到严峻挑战。因此,有必要进一步结合风电并网导则,研究提升电网故障下多风电系统低电压运行适应能力的控制方法。论文首先建立了多风电系统的正负序等效电路,分析了影响系统公共连接点电压的因素。其次,分析了不对称故障下单风电场电压控制的限制条件,然后以改善不同运行场景下风电系统低电压运行适应能力为目标,提出了多风电系统暂态电压协同控制方法。最后,建立了多风场暂态电压控制仿真计算模型,仿真结果表明所提方案可有效改善公共连接点暂态电压水平,并灵活实现最大风能跟踪,为有效提升多风电系统的低电压运行适应能力奠定基础。

Wind farms are often located in the rural power grid with inverse distribution characteristics to the load center.As a result,wind power generation systems have poor voltage support capability under asymmetric short-circuit fault conditions,and the low-voltage operation adaptability of wind turbines is severely challenged.Therefore,it is necessary to study the control methods to improve the low-voltage operation adaptability of multi-wind power systems under grid faults,aimed at wind power grid-connection guidelines.Firstly,this paper establishes the positive and negative sequence equivalent circuit of the multi-wind power system,and analyzes the factors affecting the voltage at the common connection point of the system.Secondly,the constraints of single wind farm voltage control under asymmetric faults are analyzed,and then a cooperative control method of multi-wind power systems transient voltage is proposed,with the goal of improving the low voltage operation adaptability of wind power generation systems with different operation scenarios.Finally,a multi-wind farm transient voltage control simulation model is established,and the simulation results show that the proposed scheme can effectively improve the transient voltage level at the common connection point,and flexibly achieve the maximum wind energy tracking,which laying the foundation for effectively improving the low-voltage operation adaptability of multi-wind power systems.