电网友好型风电场低电压穿越建模、仿真与验证研究

With the connection of large-scale wind farms to the grid, the low voltage ride-through (LVRT) quality of single wind turbine generators and wind farms has become an urgent problem. By fully considering grid requirements for the integration of wind turbine generators, this research has studied the interaction of doubly-fed induction generator (DFIG) and direct drive permanent magnet synchronous generator (PMSG) with the grid during fault, dynamic reactive power control strategies, technical solution of grid voltage support, protection of converters and hardware circuit control aiming at enhancing the LVRT ability of wind turbine generator. Based on the abovementioned analysis, LVRT models of DFIG and PMSG are developed in software platform and further modified through the comparison between experimental results and real test data to ensure their accuracy and practical applicability. On the basis of single wind turbine generator LVRT model, LVRT models of wind farms containing the same type or different types of wind turbine generators have been further established, and strategies for reactive power optimal coordinated control of DFIG and PMSG during the period of low voltage have been put forward, which provide a positive guidance in theory and technical support for the safe and grid friendly operation of large scale wind farms.

随着大规模风电的并网运行，风电机组和风电场的低电压穿越（LVRT）能力已成为亟待解决的问题。本项目通过分析电网故障期间双馈和直驱式风电机组同电网之间的交互作用机理，并以现代风电并网导则为依托，深入研究了风电机组动态无功功率控制策略、电网电压支撑技术方案、风电机组变流器保护技术和提高风电机组LVRT能力的硬件电路控制。并基于以上研究，在软件平台上开发了双馈和直驱式风电机组LVRT仿真模型，通过与试验结果和风电场实测数据进行对比验证，进一步修正风电机组LVRT模型，确保模型的准确性和实用性。在单机LVRT模型基础上，进一步建立了含同一类型和不同类型风电机组的风电场LVRT模型，提出低电压穿越期间双馈和直驱式风电机组无功功率最优协调控制策略，为大型风电场的并网稳定运行提供积极的理论指导和技术支持。

项目以现代风电并网导则为依托，对当前获得广泛应用的变速恒频风电机组和风电场并网的建模和控制进行了深入研究。首先，针对双馈式风电机组的结构和数学模型，建立了双馈风电机组的控制系统，在软件平台上建立了具备低电压穿越功能的双馈风电机组机电暂态仿真模型，与实测双馈风电机组的相关特性数据进行仿真对比，进一步修正相关参数，确保了双馈式风电机组机电暂态模型的有效性和准确性。其次，在考虑风电场内风电机组运行特性的相似性与差异性的基础上，将风电场内的机组划分为同调机群，根据不同机群的运行特性分别采用了恒电压控制和恒功率因数控制的无功协调控制策略，并提出了一种综合考虑风电场电压稳定和无功裕度的风电场稳定系数指标来评价风电场无功控制策略的优劣，仿真验证了该基于风电机组运行特性划分同调机群的无功协调控制策略能在有效支持电网电压的同时，还有相对较高的无功裕度来满足电网的进一步无功需求。再次，针对有Crowbar保护的双馈风电场，项目提出了基于Crowbar动作分群的风电场无功控制策略，仿真验证了所提策略能充分发挥DFIG背靠背变流器的优势，有效提高双馈风电场的低电压穿越能力。然后，运用特征值分析方法获得了直驱风电机组电磁暂态降阶模型，并在软件平台上搭建了仿真模型；最后，依据直驱式风电机组采用双PWM全功率变流器，能够独立控制风电机组发出的有功功率与无功功率的优势，控制电网侧变流器根据电网电压的跌落程度发出无功功率，实现了直驱风电场参与系统电压调节的功能。