风力电动机通常作为分布式电源并入主配电网中,针对传统配电网继电保护策略无法解决并网带来的功率方向随机性及系统状态改变等问题,文中在DFIG内部的保护模块中加入自适应电流保护策略,这样不但抗干扰性强,且可自动判断电网风机的存在状态,同时还能加快熔断后恢复速度.而在风电场内部系统保护模块中加入主从机纵连保护策略,便可通过分机功率方向对电路中故障发生的位置进行准确判断.仿真结果表明,所提继电保护策略相较传统方法的熔断恢复时间缩短了0.15 s,且在大规模系统中也能够对故障发生的位置进行准确地判断.

文章主要讨论了大规模风电接入和继电保护之间的关联,并为此提出了一些合理的保护措施,希望能更好的维护电力系统.

电网三相跌落故障下,两级式光伏逆变器的直流母线电压及并网电流会不稳定,从而导致光伏逆变器由于过压或者过流而脱网,而光伏逆变器的脱网又会恶化电网系统的安全运行,从而造成更为严重的事故.针对这一问题,文中首先在分析三相光伏并网逆变系统结构及控制的基础上,提出电网故障下保持系统直流母线电压及并网电流稳定的控制策略,且采用所提控制策略下的光伏并网逆变器能够在电网故障期间对其提供一定的无功支持.最后,搭建了三相光伏并网逆变系统的数字仿真平台,结果验证了所提控制策略在三相跌落故障下的有效性与优越性.

DC bus voltage and grid-connected current of the traditional two-stage PV inverter will be unstable under power grid′s unbalanced fault,which causes the PV inverter′s outage due to overvoltage or overcurrent. Outage of the PV inverter can worsen the secure operation of power grid and cause more serious accidents. To solve this problem,a control strategy was presented based on analysis of the three-phase PV grid-connected inverter system′s topology and control method. During the fault of power grid,the proposed strategy could not only ensure the stability of DC bus voltage and grid-connected current,but also make the PV inverter to provide a certain reactive power support to the grid. An experimental system and digital simulation platform of the three-phase PV grid-connected inverter system were built,and the validity and superiority of the proposed control strategy under the power grid′s unbalanced fault are verified by simulation results.