抑制背景谐波振荡的无限长传输线模拟器研究

The propagation of background harmonics throughout a power-distribution system may result in resonant magnifying of the harmonic voltages and current on loads and PCC and exceed the utility operation standard, which seriously affects the utility components security and usage life such as reactive power compensation device and passive filter. With impedance model it is difficult to achieve perfect compensation and background harmonics mitigation by passive filter and traditional active power filter. R-APF can effectively suppress the propagation of harmonic voltages along the feeder lines in the distribution system. However, due to sensitivity to the installing position of the system, installation of an active or passive filter on a long-distance power distribution feeder is limited to end of radiation line or middle of loop lined. In this project, an infinite transmission line simulator (ITLS) is presented by applying distributed parameter model. Compared to the R-APF, it is insensitive to installing position parameter of characteristic impedance. Combined with optimized network structure, it is realized to suppress background voltage propagation. The project aims to optimize power quality of supply system by analyzing harmonic propagation of comprehensive strategy in view of the complex network structure. Meanwhile, referring to the grid-connected inverter secure operation under background harmonic, its parameter designing will be considered. The control scheme of interface inverter hybrid functionality of background harmonic mitigation will be researched to improve the capability of distribution system background harmonic mitigation. The purpose of the project is to provide a more secure, reliable, low cost electricity environment.

背景电压谐波在传输过程中因谐振而产生背景谐波放大振荡，导致用户负荷及PCC 的谐波电压电流超标，严重影响无功补偿装置、无源滤波装置及用电设备的安全运行与使用寿命。应用阻抗模型，结合无源滤波与有源滤波很难实现背景电压谐波的完全谐波补偿和抑制。阻性有源滤波器能够有效地抑制配电系统馈电线上谐波电压的传播，但安装位置受限，影响系统的推广使用。本课题应用分布参数模型，分析设计无限长传输线模拟器，相比于阻性有源滤波器解决对位置敏感性问题，结合优化网络结构，实现抑制背景电压振荡。针对复杂网络结构，分析谐波振荡放大的组合式抑制策略，优化供电系统电能质量。同时从并网逆变器单元入手，分析接口变流器背景谐波下安全运行的参数设计，研究并网接口逆变器复合背景谐波抑制功能，增加系统背景谐波电压治理能力。

射线型配电网和环型配电网中，系统电感和寄生电容会引起背景电压谐波在传输过程中谐振，导致配电网中谐波含量增加，电能质量下降，给电力系统造成损失或威胁电气设备的安全运行。本项目基于均匀传输线理论的分布参数模型和集总参数模型，对两种类型的配电网(射线型配电网和环型配电网)线路上的背景谐波电压增殖放大现象进行了讨论分析。针对环型配电网中谐波谐振现象，提出了在环型配电网中点安装等效无限长有源电力滤波器（Long-Feeder Simulator-Based Active Power Filter, LFS-APF），以及一种基于双点检测单阻性有源滤波器（Double Point Detective of Single Resistive Active Power Filter, DPDSRAPF）的谐波抑制策略。这些方案相比于在环型配电网中点安装阻性有源电力滤波器（Resistive Active Power Filter，R-APF）的传统方案可以获得更好的谐波抑制效果。同时，针对射线型配电网中的谐波谐振现象，在传统的R-APF基础上提出了双阻性有源电力滤波器（Double-RAPF, D-RAPF），以及分频动态增益调节的有源滤波器（Discrete Frequency Automatic Gain Active Filter, DFAGTAF）最优安装位置的谐波衰减方案，为滤波器的安装位置提供了理论依据。最后，从并网逆变器单元入手，对末端是微电网结构的配电网系统的谐波抑制策略进行了研究 ，提出了分频阻性有源滤波器（Discrete Frequency Resistive Active Power Filter, DFRAPF）等谐波抑制策略，可有效抑制末端微电网结构系统中的背景谐波放大现象。