风电大规模并网时机组级电压控制技术研究

Research on Unit-level Voltage Control Technology for Large Scale Grid-connected of Wind Power

风电机组电压控制在维持风电场并网后的系统电压稳定方面具有较大的优势,且对于提高电网运行经济性具有重要意义。此处主要从风机电压控制的3个关键技术点展开分析。在无功极限方面主要针对相对复杂的双馈型风电机组(DFIG)展开分析,定子侧考虑定转子电流极限的约束,网侧考虑了网侧变流器无功能力限制。风机在无功极限内参与调压时其无功支撑能力远大于按照0.9~0.95功率因数运行所具备的无功支撑能力。无功分配及环流抑制方面,采用了基于下垂特性的电压控制,避免了无功环流,保证机组间无功合理分配。风机参与调压后振荡风险分析及抑制方面,通过仿真模拟了振荡过程,分析了振荡影响因素,合理设置电压控制速度以规避振荡风险。最后,基于1.5 MW双馈风电实验台开展了控制策略测试,验证了所提方法的可行性。

The voltage control of wind turbines has great advantages in maintaining the voltage stability after the wind farm is connected to the grid,and it is of great significance to improve the economy of power grid operation.Three key technical points of that are mainly analyzed.In terms of reactive power limitation,doubly-fed induction generator(DFIG)are mainly analyzed.The stator side considers the current limitation constraints of stator and rotor,and the grid side considers reactive power limitation of grid side converter.After considering reactive power limitation,the overall reactive power supporting capability of wind turbine is much larger than that of the wind turbine operating at 0.9~0.95 power factor.For reactive power distribution and circulation suppression,voltage control based on droop characteristics is adopted to avoid reactive power circulation and ensure reasonable reactive power distribution among units.Regarding the oscillation risk analysis and suppression after voltage regulation,the oscillation process is simulated,the factors affecting the oscillation are analyzed,and the voltage control speed is reasonably set.Finally,a control strategy test is carried out to verify the feasibility of the proposed method based on the 1.5 MW double-fed wind power test bench.