双馈风电场柔性高压直流接入下的网侧变换器改进Backstepping控制策略

Improved Backstepping control strategy for GSVSC of DFIG wind farm with VSC-HVDC grid-integration

为了增强风电场柔性直流输电(VSC-HVDC)接入结构的强健性,改善电力系统风电接入点的电能质量和提高电力系统风电接入能力,以双馈感应电机(DFIG)风电场VSC-HVDC接入结构为例,针对其电网侧电压源换流器(GSVSC)提出了改进的Backstepping控制策略。该策略在充分考虑实际控制运行中可能出现的交直流侧系统参数变动、交流电网电压波动以及其他不确定外界扰动的基础上,引入sign函数和有界的集总不确定量于各次递回迭代控制力设计中,以增强GSVSC运行控制中应对系统参数变动以及外界不确定扰动的能力。所提控制策略的稳定性依据Lyapunov稳定原则进行了推导证明。通过3种不同干扰模式下的仿真验证以及与同等条件下传统双闭环PI控制效果的对比分析充分表明所提控制策略是有效的。

An improved Backstepping control strategy of GSVSC（Grid-Side Voltage-Source Converter）is proposed for DFIG（Doubly-Fed Induction Generator） wind farm with the grid-integration structure of VSC-HVDC（Voltage Source Converter-High Voltage Direct Current） to improve its grid-integration robustness, the electrical energy quality of its integration point and its grid-integration capability. With full consideration of the parameter variations at both AC and DC sides,the AC voltage fluctuation and other uncertainties, sign function and bounded lumped uncertainties are introduced to the control force design for each iterative turn to improve the anti-disturbance performance of GSVSC. The stability of the proposed control strategy is deduced according to Lyapunov principle. Simulative results of three disturbance modes are compared with those by traditional double-loop PI control strategy under same conditions,which proves the effectiveness of the proposed control strategy.