基金项目:
国家自然科学基金(51577075);
中央高校基本科研业务费专项资金(2014QN223);
Project supported by National Natural Science Foundation of China (51577075), the Fundamental Research Funds for the Central Universities (2014QN223);
摘要
为探讨风电机组轴系振荡这一问题,推导出了双馈风电机组电磁、机械耦合支路的传递函数,首次建立了完全反映双质量块动态特性的轴系振荡复转矩分析模型,得到轴系振荡同步转矩系数及阻尼转矩系数的表达式,并进一步分析了该系数随风电机组不同运行转速的变化规律,揭示了风电机组在最大风功率跟踪(maximum power point tracking, MPPT)控制模式下运行转速对其轴系振荡模式的作用机理。最后,通过特征值分析和时域仿真分析验证了所建模型及分析结果的准确性。
关键词 :轴系振荡;
双馈风电机组;
运行转速;
复转矩分析;
小干扰稳定;
DOI:10.13336/j.1003-6520.hve.20170527046
ABSTRACT
The torsional oscillation of doubly-fed induction generator (DFIG) based wind turbine (WT) is discussed. By deducting the transfer functions of both the electromagnetic loop and mechanical loop of DFIG, a complex torque analysis model which could thoroughly represent the two-mass model’s dynamics is established for the first time. Expressions of the synchronizing torque coefficient and damping torque coefficient are also obtained. Based on this model, the operating speed’s impacts on those coefficients are further analyzed. And the influence of the operating speed on torsional oscillation when DFIG is under the maximum power point tracking (MPPT) control mode is stated. Finally, the theoretical analysis results are verified by Eigen-value analysis and time-domain simulation results.
KEY WORDS :torsional oscillation;doubly-fed induction generator based wind turbine;operation point;complex torque analysis;small signal stability;
双馈风电机组采用两个背靠背、通过直流环节连接的变频器进行励磁。其中转子侧变频器(rotor side converter, RSC)主要用于实现风电机组输出有功、无功功率的解耦控制。网侧变频器(grid side converter, GSC)则主要用于保持直流母线电压的稳定及保证风电机组的正常运行。本文中的变频器主要用于实现MPPT控制和单位功率因数控制。
\({{H}_{2}}\left( s \right)=\frac{{{P}_{\operatorname{m}}}}{\omega _{t}^{2}}\frac{K+Ds}{2{{H}_{t}}s+{{{P}_{m}}}/{\omega _{t}^{2}}\;}\) (20)
2.3 轴系振荡转矩系数
令Re\(\left\{ H\left( s \right) \right\}\)和Im\(\left\{ H\left( s \right) \right\}\)分别代表复频域中H(s)的实部与虚部。则有
\(H\left( s \right)=\operatorname{Re}\left\{ H\left( s \right) \right\}+\text{j}\operatorname{Im}\left\{ H\left( s \right) \right\}=\operatorname{Re}\left\{ H\left( s \right) \right\}+\)
\(\text{j}{{\omega }_{d}}\frac{\operatorname{Im}\left\{ H\left( s \right) \right\}}{{{\omega }_{d}}}=\operatorname{Re}\left\{ H\left( s \right) \right\}+\frac{\operatorname{Im}\left\{ H\left( s \right) \right\}}{{{\omega }_{d}}}s\) (21)
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