Fast and accurate acquisition of positive sequence components of unbalanced grid voltage is an essential requirement to ensure the safety operation of the grid-connected inverter.To improve the extraction speed of pos...Fast and accurate acquisition of positive sequence components of unbalanced grid voltage is an essential requirement to ensure the safety operation of the grid-connected inverter.To improve the extraction speed of positive sequence components of unbalanced voltage,this study proposes a sampling period delay filter(SPDF)to quickly separate positive and negative sequence components by delaying two sampling periods of grid voltage in dq frame.With the SPDF method,only one coordinate transformation is required and the computational burden can be reduced apparently.Then,the noise immunity performance of the proposed SPDF algorithm is investigated;and the corresponding solution,operation period delay filter(OPDF),can guarantee the desired fast response performance under the premise of limiting the amplified noise within the acceptable range.Finally,the feasibility and priority of the above two algorithms have been verified by the simulation and experimental results.展开更多
The admittance is a strong tool for stability analysis and assessment of the three-phase voltage source converters(VSCs) especially in grid-connected mode.However, the sequence admittance is hard to calculate when the...The admittance is a strong tool for stability analysis and assessment of the three-phase voltage source converters(VSCs) especially in grid-connected mode.However, the sequence admittance is hard to calculate when the VSC is operating under unbalanced grid voltage conditions. In this paper, a simple and direct modeling method is proposed for a three-phase VSC taking the unbalanced grid voltage as a new variable for the system.Then coupling in the three-phase system can be calculated by applying the harmonic linearization method. The calculated admittance of three-phase VSCs is verified by detailed circuit simulations.展开更多
针对实际电网电压中存在实时动态变化的谐波运行环境,提出电压源型并网变流器广义谐波下的滑模变结构直接功率控制(sliding-mode-based direct power control,SMCDPC)策略;其实施是针对所有次数谐波,该控制策略不需实时精确的电网谐波...针对实际电网电压中存在实时动态变化的谐波运行环境,提出电压源型并网变流器广义谐波下的滑模变结构直接功率控制(sliding-mode-based direct power control,SMCDPC)策略;其实施是针对所有次数谐波,该控制策略不需实时精确的电网谐波次数和相位检测,具有实际工程应用价值。在以往研究成果的基础上,建立了广义畸变电网环境中的并网电压源型变流器(grid-connected voltage-sourced converters,VSC)的完整数学模型,提出3种该运行环境下的控制目标:正弦形输出电流,消除有功功率波动和无功功率波动。完成了滑模变结构直接功率控制设计。仿真结果表明,相比传统滑模变结构直接功率控制,改进的滑模变结构直接功率控制增强了电压源型并网变流器在实际电网广义电压谐波下环境中的运行能力。展开更多
基金The work was supported by the National Natural Science Foundation of China(51707091).
文摘Fast and accurate acquisition of positive sequence components of unbalanced grid voltage is an essential requirement to ensure the safety operation of the grid-connected inverter.To improve the extraction speed of positive sequence components of unbalanced voltage,this study proposes a sampling period delay filter(SPDF)to quickly separate positive and negative sequence components by delaying two sampling periods of grid voltage in dq frame.With the SPDF method,only one coordinate transformation is required and the computational burden can be reduced apparently.Then,the noise immunity performance of the proposed SPDF algorithm is investigated;and the corresponding solution,operation period delay filter(OPDF),can guarantee the desired fast response performance under the premise of limiting the amplified noise within the acceptable range.Finally,the feasibility and priority of the above two algorithms have been verified by the simulation and experimental results.
基金supported by National Natural Science Foundation of China(No.51637007,No.51507118)
文摘The admittance is a strong tool for stability analysis and assessment of the three-phase voltage source converters(VSCs) especially in grid-connected mode.However, the sequence admittance is hard to calculate when the VSC is operating under unbalanced grid voltage conditions. In this paper, a simple and direct modeling method is proposed for a three-phase VSC taking the unbalanced grid voltage as a new variable for the system.Then coupling in the three-phase system can be calculated by applying the harmonic linearization method. The calculated admittance of three-phase VSCs is verified by detailed circuit simulations.
文摘针对实际电网电压中存在实时动态变化的谐波运行环境,提出电压源型并网变流器广义谐波下的滑模变结构直接功率控制(sliding-mode-based direct power control,SMCDPC)策略;其实施是针对所有次数谐波,该控制策略不需实时精确的电网谐波次数和相位检测,具有实际工程应用价值。在以往研究成果的基础上,建立了广义畸变电网环境中的并网电压源型变流器(grid-connected voltage-sourced converters,VSC)的完整数学模型,提出3种该运行环境下的控制目标:正弦形输出电流,消除有功功率波动和无功功率波动。完成了滑模变结构直接功率控制设计。仿真结果表明,相比传统滑模变结构直接功率控制,改进的滑模变结构直接功率控制增强了电压源型并网变流器在实际电网广义电压谐波下环境中的运行能力。
