直流换相失败下双馈风电机组特性描述及暂态过电压抑制  

Characteristic Description and Transient Overvoltage Suppression of Doubly-fed Wind Turbines with LCC-HVDC Commutation Failure

作　　者：刘其辉 董楚然 吴勇 张亚灵 逄思敏 申杰 LIU Qihui;DONG Churan;WU Yong;ZHANG Yaling;PANG Simin;SHEN Jie(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University),Beijing 102206,China;Maintenance Company of State Grid Shanghai Municipal Electric Power Company,Shanghai 200063,China;Songjiang Power Supply Company of State Grid Shanghai Municipal Electric Power Company,Shanghai 201600,China)

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学),北京市102206 [2]国网上海市电力公司检修公司,上海市200063 [3]国网上海市电力公司松江供电公司,上海市201600

出　　处：《电力系统自动化》2022年第8期29-38,共10页Automation of Electric Power Systems

基　　金：国家电网公司科技项目(4000-202014051A-0-0-00)。

摘　　要：基于电网换相换流器的高压直流(LCC-HVDC)输电因传输容量大而在中国规模化风电外送中得到广泛应用。当LCC-HVDC系统发生换相失败时,其在暂态过程中的无功功率大范围波动将导致送端电网电压剧烈变化,对风电的稳定运行产生极大的影响,导致脱机等事故的发生。直流系统换相失败工况与交流电网短路故障有较大差异,因此亟须对该工况下的双馈感应发电机(DFIG)暂态特性及故障穿越方法进行研究。首先,分析了换相失败时送端电网的暂态电压形态特性,揭示了暂态过电压的形成机理。然后,采用分段线性描述方法对电网电压连续变化下的DFIG暂态磁链特性进行了解析,并结合DFIG无功输出方程提出了一种适用于换相失败故障的改进低-高电压故障穿越及过电压主动抑制策略。最后,通过PSCAD仿真验证了所提策略在实现DFIG故障穿越的同时还能够进一步抑制暂态过电压,提高了系统稳定性与灵活性。The line commutated converter based high voltage DC(LCC-HVDC)transmission system has been widely used in largescale wind power transmission in China due to its large transmission capacity.When the commutation failure occurs in LCC-HVDC systems,the power grid voltage at the sending end will fluctuate dramatically due to the large range of reactive power fluctuation in the transient process,which has a huge influence on the stable operation of wind power and leads to the occurrence of off-grid accidents.Meanwhile,the commutation failure in DC systems is different from the short circuit fault in the AC power grid.Therefore,it is urgent to study the transient characteristics and fault ride-through method of the doubly-fed induction generator(DFIG).Firstly,transient voltage characteristics of the commutation failure at the sending end are analyzed and the mechanism of transient overvoltage is revealed.Then,the stator flux characteristics of DFIG with the continuous change of the power grid voltage are analyzed by the piecewise linear description method.An improved active suppression strategy for low-and high-voltage ride-through and overvoltage is proposed for commutation failure according to the reactive power output equation of DFIG.Finally,PSCAD simulation verifies that the proposed strategy can not only achieve fault ride-through of DFIG,but also suppress the transient overvoltage,which improves the system stability and flexibility.

关 键 词：换相失败 双馈感应发电机 暂态电压 故障穿越 过电压主动抑制 

分 类 号：TM721.1[电气工程—电力系统及自动化] TM346