电网连锁故障下双馈式风力发电机动态特性及鲁棒性增强穿越研究

Cascading voltage fault is a big challenge for wind power conventional fault ride through (FRT) operation and needs to be solved urgently. The proposed project is to research on the basic theory and key technology of the doubly-fed induction generator (DFIG) dynamic analysis under cascading voltage fault with phase angel jumps and its enhanced robustness FRT control. Firstly, On deriving the dynamic equations of the key variables of the DFIG both under balanced and unbalanced faults, with considering the phase angel jumps, interval of cascading fault, electromagnetic transient characteristics, magnetic saturation characteristics, bandwidth of the controllers, reactive power and output and protection circuit, the principle of the DFIG FRT fail can be extracted. Secondly, on designing the new H∞ current control method based on stationary coordinate, the robustness and dynamic FRT performance of DFIG for cascading fault conditions with phase angel jumps are improved, in which conventional control has bad transient performance because of the uncertainties of generator, the complexity of external disturbance, the oscillatory instability and the bias of coordinate orientation. Thirdly, on developing a coordinated control scenario with circuit protection and reactive power output control, the voltage swell and the DC link over-voltage can be mitigated. The research of the proposed project can provide a theoretical basis and innovative solution for the ride through of the cascading conditions with phase angel jumps of the DFIG, which also has an important application value for avoiding severe cascading trip failures.

电网"跌落-骤升"连锁故障穿越是提高目前风电并网适应性亟需解决的问题。本项目研究在伴随相位跳变的复杂电网连锁故障下，双馈式风力发电机不脱网运行及鲁棒性增强控制的基础理论与关键技术。首先，建立各类对称、非对称连锁故障下，考虑相角跳变、电磁暂态特性、控制器时间常数、锁相环时间常数、磁饱和特性、无功输出及保护电路投切等多因素约束的暂态分析模型，为完整揭示风机动态穿越性能提供理论依据；然后，建立基于静止坐标系下的鲁棒H∞电流控制器，解决该类故障下控制系统对象参数不确定、外部扰动不确定、易引发振荡失稳、坐标系定向偏差等问题，为增强故障下风机穿越性能提供新的方法；最后，提出机侧-网侧无功协调输出策略，避免恒压控制引发电压骤升，并抑制电压骤升后母线电压过调制，最终实现风机连锁故障穿越。本项目研究成果可对风机在复杂电压故障下的运行与控制提供理论依据和技术支撑，对避免实际风机连锁脱网事故具有重要的应用价值。

电网"跌落-骤升"连锁故障穿越是提高风电并网适应性的现实需求。电网电压连锁故障下风机电流控制呈现出对象参数不确定、外部干扰增加、易引发振荡失稳、坐标系定向偏差等特点，若能划归为一类带有扰动不确定性系统的控制问题，设计兼具鲁棒性、稳定性和快速性的控制器，并结合矢量控制的磁链-转矩解耦特性，可有效提高该类故障下风机的穿越性能。.本项目完成了电网电压连锁故障并伴随电压相位跳变下双馈式风力发电机的动态响应机理分析。论证了电网电压连锁故障不仅会激发定子磁链暂态分量，从而导致转子暂态过电流，同时导致母线电压瞬态过冲出现稳态过电压，增加风机故障穿越难度。同时论证了电压相位跳变后会加剧电网故障下转子侧过电流和母线过电压的机理。.在完成对电网连锁故障下风机响应特性分析基础上，本项目建立了考虑实际电机参数和不同电压故障下谐波的不确定性风机模型，设计了基于H∞控制理论的转子电流鲁棒控制器，进而成功实现了电网电压骤降并伴随复杂扰动下的风机故障穿越及谐波电流抑制。.在成功建立转子电流鲁棒控制器的基础上，本项目提出了电网电压连锁故障下双馈式风力发电机的增强穿越策略，通过对转子侧变流器采用鲁棒控制策略，改善了电压故障后双馈风力发电机转子过电流响应。网侧变流器采用改进无功电流控制策略，增强了双馈式风力发电机的低电压和高电压连锁穿越性能，并提出了一种转子侧撬棒电路投切策略。.本项目成功建立了电网复杂连锁故障下计及多不确定因素的双馈式风机模型，分析了转子电流动态响应特性，为完整揭示风机动态穿越性能提供理论依据。成功利用了H∞控制理论设计转子电路鲁棒控制器，为增强故障下风机穿越性能提供了新的思路。提出了机侧-网侧无功协调输出策略，避免恒压控制引发电压骤升，并抑制电压骤升后母线电压过调制，实现了风机连锁故障穿越。本项目研究成果对风机在复杂电压故障下的运行与控制提供理论依据和技术支撑，对避免实际风机连锁脱网事故具有重要的应用价值。