In order to solve problems in high dynamic environment, a frequency-locked loop （FLL） assisted phase-locked loop （PLL） is put forward for carrier tracking. On the basis of the analysis of discriminators, the total...In order to solve problems in high dynamic environment, a frequency-locked loop （FLL） assisted phase-locked loop （PLL） is put forward for carrier tracking. On the basis of the analysis of discriminators, the total phase error of the tracking loop is analyzed and a general error expression is derived. By using linearization and Jaffe-Rechtin coefficients, the performance of a special first order FLL-assisted second order PLL is analyzed to get a closed expression. Analysis results and simula- tions show that there exist an optimal FLL loop bandwidth and a optimal PLL loop bandwidth which can make the phase jitter much less than that when the PLL is used alone.展开更多
弱电网的主要电气特性之一为高电网阻抗。高电网阻抗易导致电网电压波形畸变,畸变的电网电压会使光伏并网逆变器锁相环出现偏差甚至失效,并导致并网电能质量变差。针对这一问题,以LC型单相光伏并网逆变器为研究对象,提出采用基于2阶广...弱电网的主要电气特性之一为高电网阻抗。高电网阻抗易导致电网电压波形畸变,畸变的电网电压会使光伏并网逆变器锁相环出现偏差甚至失效,并导致并网电能质量变差。针对这一问题,以LC型单相光伏并网逆变器为研究对象,提出采用基于2阶广义积分器锁频环(second order generalized integrator frequency locked loop,SOGI-FLL)同步方法来实现逆变器与弱电网的同步。在分析不同电网状态尤其是弱电网对逆变器影响的基础上,详细阐述SOGI-FLL的工作原理和实现方法。仿真和实验结果表明,该同步方法在电网电压扰动及过零点震荡情况下均可稳定可靠工作,对电网电压变化具有较强的鲁棒性和适应性,与传统过零同步方法相比,SOGI-FLL同步方法可提高弱电网下光伏并网逆变器的可靠性。展开更多
文摘In order to solve problems in high dynamic environment, a frequency-locked loop （FLL） assisted phase-locked loop （PLL） is put forward for carrier tracking. On the basis of the analysis of discriminators, the total phase error of the tracking loop is analyzed and a general error expression is derived. By using linearization and Jaffe-Rechtin coefficients, the performance of a special first order FLL-assisted second order PLL is analyzed to get a closed expression. Analysis results and simula- tions show that there exist an optimal FLL loop bandwidth and a optimal PLL loop bandwidth which can make the phase jitter much less than that when the PLL is used alone.
文摘弱电网的主要电气特性之一为高电网阻抗。高电网阻抗易导致电网电压波形畸变,畸变的电网电压会使光伏并网逆变器锁相环出现偏差甚至失效,并导致并网电能质量变差。针对这一问题,以LC型单相光伏并网逆变器为研究对象,提出采用基于2阶广义积分器锁频环(second order generalized integrator frequency locked loop,SOGI-FLL)同步方法来实现逆变器与弱电网的同步。在分析不同电网状态尤其是弱电网对逆变器影响的基础上,详细阐述SOGI-FLL的工作原理和实现方法。仿真和实验结果表明,该同步方法在电网电压扰动及过零点震荡情况下均可稳定可靠工作,对电网电压变化具有较强的鲁棒性和适应性,与传统过零同步方法相比,SOGI-FLL同步方法可提高弱电网下光伏并网逆变器的可靠性。
