基于PR控制的海上风电场并网VSC-HVDC系统

摘要

提出了一种新的适用于海上风电场并网的新型高压直流输电(Voltage Source Converter based HVDC,VSC-HVDC)系统的比例谐振(Proportional Resonant,PR)控制策略.该方法充分利用PR控制器能够在αβ坐标系下对交流输入信号无静差控制的特点,将矢量控制策略下的有功电流和无功电流分量转换到αβ坐标系下进行调节,实现风电场和电网侧换流器维持直流电压稳定以及有功、无功功率的解耦控制.与常用的双闭环PI控制相比,该策略无需多次坐标变换和前馈解耦控制,且易于实现对系统谐波电流的补偿,降低了实现难度,提高了系统的鲁棒性和并网电能质量,为海上风电场并网VSC-HVDC系统提供了一种优化的控制方案.%A novel proportional resonant (PR) control strategy in the VSC-HVDC system for offshore wind farms is proposed in the paper. The technique took full advantage of the characteristics of PR controller, which can realize zero steady-state error of AC input signal in the stationary frame. In the method,by using the vector control strategy, the active and reactive current component were transformed into the stationary frame to achieve the target of keeping the DC-link voltage constant,and decoupling the active and reactive power. Compared with the common double close-loop proportional integral controller,the PR technique is better in harmonic compensation without the complex coordinate transformation, the decoupling and the feedforward control. Also the control algorithm is easy to be realized while the robustness and power quality is improved. It provides an optimized control scheme in the VSC-HVDC system for offshore wind farms.