并网型光伏电站直流侧电磁干扰关键问题研究

The aim of this research project is to establish conducted emission & radiated emission modeling in large area photovoltaic (PV) plant. By means of that, we can analysis those electromagnetic interference ( EMI ) negative effects on insulation aging of PV equipments. And finally we will discover an effective EMI noise attenuation method. The main content includes: (1) Conducted EMI modeling of PV inverter, long cable and large area solar cell array. Calculating reflection and standing wave in order to determine the common mode (CM) voltage at each end of cable and solar cell. (2) Analysis the influence of high du/dt CM spike voltage on the insulation aging of PV equipments. That include the partial discharge behavior, the space charge behavior, the dielectric loss, the aging characteristics and the description parameters of the insulation. (3) Modeling of the radiated field system of the PV arrays and then estimate its strength and distribution characteristic. (4) Proposing a novel distributed filtering method for the PV grid-connected system. Analysis the relationship between the impedance of filter and long cable, filter and PV array, filter and PV inverter, so that we may explore the feasibility of attenuating PV EMI at a lower cost. This project will have great theoretical and practical significance on the research of EMI in PV grid-connected system.

本项目旨在研究光伏并网逆变器产生的电磁干扰在大面积光伏阵列内的传导及辐射机制，分析其对光伏设备绝缘材料寿命的影响机理，探索干扰抑制的有效途径。主要研究内容包括：（1）建立包含光伏逆变器共模等效电压源、长电缆、大面积光伏阵列的传导干扰传播模型，计算反射与驻波，确定电缆终端和光伏组件承受的共模电压幅度；（2）研究高du/dt共模尖峰电压对光伏设备绝缘寿命的影响，包括绝缘的局部放电、空间电荷行为、介质损耗、老化特征和表征参量，建立绝缘材料的老化模型；（3）建立光伏阵列辐射场的模型，理论预估其辐射场强度大小和分布特性；（4）提出适用于光伏并网系统的分布式滤波方法，研究滤波器与长电缆、滤波器与光伏阵列、滤波器与逆变器相互之间的阻抗匹配关系，探讨以较小代价抑制太阳能光伏系统电磁干扰的可行性途径。本项目对于光伏并网系统电磁干扰问题及其对策的研究具有关重要的理论意义和明确的应用价值。

光伏电站的共模漏电流带来很多负面问题，包括危害人身设备安全，增大电磁干扰，增加系统的额外损耗，加速光伏板的老化过程，引起共模滤波器的饱和，降低滤波效果，造成系统的损坏等。本项目建立了包含光伏逆变器共模等效电压源、长电缆、大面积光伏阵列的传导干扰传播模型，确定了电缆终端和光伏组件承受的共模电压幅度；研究了长期高压电致老化的微观机理以及漏电流在光伏组件内部的分布特性；建立了光伏阵列辐射场的模型，理论预估其辐射场强度大小和分布特性；提出了适用于光伏并网系统的分布式滤波方法，研究了滤波器与长电缆、滤波器与光伏阵列、滤波器与逆变器相互之间的阻抗匹配关系，探讨了以较小代价抑制太阳能光伏系统电磁干扰的可行性途径。本项目对于光伏并网系统电磁干扰问题及其对策的研究具有关重要的理论意义和明确的应用价值。