Based on the structure of wind turbines and its grid-connection principle, an improvedlow voltage ride through control scheme with "DC chopper + reactive compensation" of PMSG is proposed. An improvedlow voltage ride through control scheme with DC chopper and series dynamic braking resistor of DFIG is adopted. The grid-connection simulation models of PMSG and DFIG which have thecapability of low voltage ride through are built in the PSCAD/EMTDC. Based on " Technical rule for connecting wind farm to power system", the low voltage ride through capability are verified with voltage sag generator (VSG) for PMSG and DFIG. Combined with the accessing scheme of Dabancheng wind farm group, a simulation example of wind farm groups which all the PMSG and DFIG have the capability of low voltage ride through is built, the characteristics of wind farm groups during fault ride-through in condition of different fault types of tie line and voltage drop at wind farm outgoing line as well as voltage drop at tie line between the groups are researched. Results indicate that the voltage drop of grid-connected large scale wind farms outgoing line have influence on voltage and frequency for the adjacent wind farm and power system, the whole wind power system can be restored to steady state operationafter the failure.Research results contribute to analyze the running characteristic of grid-connected large scale wind farms and improve the receptivity ability for wind power.%结合风电机组的结构和并网原理,对直驱风电机组提出了"卸荷电路+无功补偿"的低电压穿越改进控制方法,对双馈风电机组采用了DC-Chopper和SDBR(series dynamic braking resistor)代替Crowbar的低电压穿越改进控制方法.以 PSCAD 为平台分别构建了具备低电压穿越能力的直驱风电机组和双馈风电机组的并网仿真模型;结合风电并网技术规程,采用电压跌落器仿真验证了直驱、双馈风电机组在电网电压跌落下的低电压穿越能力.参照新疆达坂城实际风电场群接入系统方案,构建了包含具备低电压穿越能力的直驱、双馈风电机组的集群风电场仿真算例,研究了风电场送出线故障、集群风电场送出线电压跌落、系统线路电压跌落时风电场群故障穿越特性.仿真结果表明:集群接入风电场送出线电压跌落会影响相邻风电场及系统的电压和频率,故障结束后整个风电接入系统可以在风电接入技术规程要求的时间内恢复至稳态运行状态.研究成果有助于分析风电大规模集群接入系统的运行特性,提高电力系统对风电的接纳能力.
展开▼
