摘要
电网发生短路故障时,风机需要向系统提供无功功率支撑电网电压恢复。弱电网不对称故障时如果只向系统注入正序无功功率,在提升故障相电压的同时会导致非故障相电压抬升,加剧风机机端三相电压不平衡度,因此需要风机注入一定的负序无功功率来抑制非故障相电压抬升。为了进一步优化不对称故障下永磁直驱风机的故障相电压支撑策略,首先建立电网不对称故障下风机送端系统数学模型及正负序解耦控制锁相环,然后推导风机机端电压与有功无功之间的耦合关系。提出以机端故障相电压最高为优化目标,约束条件为三相电流最大值不超过换流器限流上限,在这种情况下风机发出无功的同时输出一定的有功功率更有利于非故障相电压的支撑。根据华北某实际风电送端系统在MATLAB/Simulink中搭建仿真模型,验证单相接地故障时该控制策略的可行性和有效性。
When the power grid is short circuited, the fan needs to provide reactive power to the system to support the voltage recovery of the power grid. If only positive sequence reactive power is injected into the system in case of asymmetric fault of weak current network, the voltage rise of non fault phase will be caused while the fault phase voltage is raised, which will aggravate the unbalance of three-phase voltage at the fan end. Therefore, it is necessary to inject certain negative sequence reactive power into the fan to suppress the voltage rise of non fault phase. In order to further optimize the support strategy of fault phase voltage of permanent magnet direct drive fan under asymmetric fault, we first established the mathematical model of fan supply end system and phase locked loop of positive and negative sequence decoupling control. Then the coupling relationship between the voltage and active and reactive power of fan terminal was deduced. The paper proposed that the maximum fault phase voltage at the end of the machine is the optimization objective, and the constraint condition is that the maximum value of three-phase current does not exceed the current limit of the converter. In this case, the fan can generate reactive power and output a certain active power, which is more conducive to the support of non-fault phase voltage. According to the simulation model of a wind power transmission terminal system in North China in Matlab/Simulink, the feasibility and effectiveness of the control strategy were verified.
作者
盛四清
田颢璟
王倩
SHENG Siqing;TIAN Haojing;WANG Qian(School of Electrical and Electronic Engineering,North China Electric Power University,Baoding 071003,China)
出处
《华北电力大学学报（自然科学版）》
CAS
北大核心
2022年第4期73-79,112,共8页
Journal of North China Electric Power University：Natural Science Edition
关键词
永磁直驱风机
不对称故障
弱电网
无功支撑
锁相环
PMSG
asymmetric fault
weak power grid
reactive power support
phase locked loop
