风电系统网侧变换器并联方案与控制策略研究

Research on Design and Control Strategy of Paralleling Grid-side Converters of Wind Power System

面向并联的网侧变换器设计了交错式PWM方案,并基于此提出了系统在各种电网情况下的控制策略。该方案的关键是根据具体的网侧变换器为其PWM载波设计恰当的相位差。这样可显著削减因为变换器器件开关引起的电网电流谐波。该方案的另一个价值在于,在不同电网电压条件下,甚至短暂的电网故障情形下,通过对电网电压和电流的负序分量进行检测和控制。所设计的广义电网同步和电流控制器的方案可有效工作。对提出的调制策略和控制方法进行了仿真和实验,结果验证了方案正确可行。

This paper designs and performs interleaved PWM scheme for the paralleled grid-side converters,and the generalized control strategy is also proposed.The key of the program is how to determine the phase difference among the PWM carriers of different grid converters.As a consequence,the total grid current harmonic caused by converters switching will be significantly cut down.Another value of this solution is that the designed general grid synchronization and current controllers can be effective to work by detecting and controlling the negative sequence component of the grid current and voltage under various grid voltage conditions,even under transient grid fault conditions.Simulation and experiment are implemented presented to verify the validity of the proposed switching strategy and control scheme.The experimental results are good.