智能电网融合下基于FFCD-SOGI-PLL的电网状态估计

State estimation of power grid under smart grid integration based on FFCD-SOGI-PLL

在智能电网与新能源发电融合背景下,电力电子接口装置的大量使用将给系统引入额外的直流偏置。因此,电网电压信息获取算法的直流偏置抑制能力变得至关重要。二阶广义积分器锁相环(SOGI-PLL)广泛应用于电网信息的同步与提取,可以有效抑制频率波动和相位跳变对电网状态估计精度的影响,但其自适应频率反馈环节在实现谐波抑制的同时,对于电网中含有的直流偏置非常敏感。针对这一问题,提出了一种固定频率反馈的级联SOGI-PLL(FFCD-SOGI-PLL),使用级联结构输入固定电网标称频率,实现信号直流分量滤除,增强了谐波抑制性能。通过小信号模型给出其稳定性分析和参数设计方法。实验结果表明,在电网电压含有直流分量、谐波以及电网电压跌落时,设计的FFCD-SOGI-PLL可以快速稳定地对电网电压状态信息进行精确估计。

In the context of the integration smart grid and new energy generation, the extensive use of power electronic interface devices will introduce additional DC bias to the system. Therefore, the DC bias suppression capability of the grid voltage information acquisition algorithm becomes crucial. The second-order generalized integrator phase-locked loop(SOGI-PLL), which is widely used in the synchronization and extraction of power grid information, can effectively suppress the influence of frequency fluctuations and phase jumps in the power grid on the power grid state estimation accuracy, but its adaptive frequency feedback link while achieving harmonic suppression, it is very sensitive to the DC bias contained in the grid. Aiming at this problem, this paper proposes a cascaded SOGI-PLL with fixed frequency feedback(FFCD-SOGI-PLL), which uses a cascade structure and inputs a fixed nominal frequency of the power grid to filter the DC component of the signal and enhance the harmonics inhibit performance is enhanced. The stability analysis and parameter design methods are given by the small signal model. The experimental results show that the designed FFCD-SOGI-PLL can quickly and stably estimate the grid voltage state information accurately when the grid voltage contains DC components, harmonics and grid voltage drops.