VRB-SC混合储能平抑直驱式风电波动与提升故障穿越一体化研究

The key problem is that Inner Mongolia grid friendly direct-driven permanent magnet synchronous generator(PMSG) wind power generation system smooths the fluctuations of output power and achieves flexible fault ride through (FFRT). In order to deal with all kinds of grid fault and random fluctuation of wind power output more effectively, the DC side equipped with bi-directional DC/DC converter with flexible response characteristics vanadium redox flow batteries (VRB) and super capacitor (SC) is proposed. Based on the study of mathematical model, the circuit topology, working mechanism, control strategy, and the transient characteristics of the PMSG, the simulation model of type dual three-level PMSG integrated with electromechanical transient and control strategy is established, and fault recorded data is imported into simulation model to validate the ability of FFRT. By analyzing the frequency spectrum of the wind power data, wavelet transform allot frequency and make rational distribution of storage power based the value of frequence. And using the improved fuzzy method to optimize energy management strategy, the strategy can smooth output fluctuations and improve FFRT integration by rapid energy throughput. The scheme is popularized to large wind farm, which can realize space-time translation of wind power, change the fluctuant disorderly wind power into dispatchable green power, and has greatly increased the accommodation capacity of wind power in the power grid. Research results have theoretical significance and engineering value for wind farm stabilizing the power fluctuations by hybrid energy storage system.

研究内蒙古电网友好型永磁同步（PMSG）直驱式风电系统平抑出力波动和柔性故障穿越（FFRT）关键问题。提出在机组直流侧加装带双向DC/DC变换器的具有灵活响应特性的全钒液流电池(VRB)和超级电容(SC)应对各种电网故障和风电出力随机波动。在研究PMSG数学模型、电路拓扑、工作机理、控制策略、暂态特性的基础上，构建集机电暂态与控制策略为一体的混合储能式双三电平PMSG仿真模型，采用现场故障录波数据导入仿真模型，验证储能提升FFRT能力。通过对风功率数据进行频谱分析，运用小波变换分频理论，采用频率高低分配原则结合改进的模糊智能控制方法优化能量管理策略，利用混合储能快速能量吞吐实现平滑输出波动与提升FFRT一体化。推广应用于大型风电场，可实现风电功率的时空平移，使波动无序的风电成为稳定可调度的“绿色”电源，提高电网对风电的消纳容量。研究工作对储能应用于风电场平抑功率波动具有理论意义和工程价值。

为了更有效的应对直驱式永磁同步(PMSG)风电系统故障穿越运行和平抑出力波动，提出了在直流环节加装带双向DC/DC变换器的VRB-SC混合储能，利用储能的源荷二重性和灵活响应特性，以及双向柔性有功、无功控制能力，通过快速的能量吞吐提升PMSG柔性故障穿越（FFRT）能力同时彻底解决风电并网功率波动问题。后续又直接从源头入手解决问题，提出理论上可实现万能电压故障穿越的动态电压恢复器（DVR）和九开关变换器（NSC）拓扑结构实时分相补偿电网电压畸变，为解决PMSG-FFRT运行的科学难点问题提供了新的途径，这是风力发电技术与电力电子技术的一种完美组合。具体研究工作如下：1)基于两相同步旋转坐标系和两种惯例，详细推导了阶数更低、形式更为简洁、求解更加容易的PMSG动态数学模型，简化了其控制系统的设计。2)对PMSG网侧变换器在电压故障时采用了新颖的电网暂态故障时无功优先、有功受限控制策略，混合储能系统采用改进分层控制策略，优异的控制策略提高了风电系统的运行性能。3)构建了完备的2MW PMSG、卸荷电路、混合储能单元、DVR、NSC的仿真模型，对比多种策略实现PMSG故障穿越运行的优缺点，阐述电网电压畸变工况下PMSG故障穿越运行与控制的本质与规律。4)通过双向DC/DC变换器进行混合储能的能量管理，控制能量双向传输，实现了平滑风电机组输出功率的动态波动。5)为解决电网故障时风电场的无功支撑问题，提出静止同步补偿器与网侧变换器无功协调控制策略，将无功需求在二者之间协调分配，提升了风电机组和风电场无功裕度和故障穿越能力。6)在传统储能电池调度方案的基础上，从储能电池出力水平以及风电未来输出对当前储能运行影响的两个新角度，设计了百兆瓦级风储联合运行系统，验证风电的可调控性；7)就核心的串联电压补偿型DVR和并联电流补偿型有源电力滤波器（APF）改善PMSG运行特性与电能质量方案进行了小功率实验验证。研究工作可提高PMSG的运行可控性和电网友好性，为其故障穿越和平滑出力提供了新的解决方案和技术依据，有望促进风电向可调控绿色电源迈进。