光伏发电接入配电网故障机理与保护对策研究

Protection of distribution network existed misoperation and immovable by the photovoltaic power fluctuation and intermittent when PV connected into the distribution network. This project established the corresponding relationship between impedance protection and current protective adaptation of the network model and parameter through the grid connected photovoltaic station fault mechanism, the faults characteristic quantity, variation characteristics analysis from the network analysis theory. It would be discussed the cooperation relationship between reclosing operation characteristics of PV power station of low voltage ride through characteristics and the original protection and configuration based on the point of view of time; put a holographic harmonic discriminant method and parameter identification method of transient / permanent fault identification using different properties of fault total response signal; located the fault by analyzing the fault traveling wave fault location of multi-scale wavelet to obtain the feature information; completed protection of impedance angle online adjustment reduces transition resistance reference based on artificial neural network model and adaptive system; protection setting value adaptive correction using the network configuration and parameters self-tuning method model; Validation of the new protection measures and protection criterion validity through simulation experiments. Research results could be expected to solve the bottleneck problem of distribution network in photovoltaic power generation, improve the ability of safe and stable operation of the distribution network.

光伏接入配电网后，原有保护受光伏功率波动性、间歇性影响，导致保护拒动/误动，影响电网安全,制约光电规模化应用。本项目从网络分析理论出发，综合考虑多种因素，通过并网光伏站短路机理、故障特征量、特性变化趋势等分析，建立与电流/阻抗保护相适应的网络模型及参数和故障信息之间的对应关系。基于时间角度探讨光伏电站低电压穿越特性与原有保护及配置的重合闸动作特性之间的配合关系；利用不同性质下故障全响应特征信号，提出全息谐波判别法和参数辨识法实现瞬时/永久故障识别；通过对故障行波多尺度小波分析，获取故障位置特征信息进行故障定位；结合人工神经网络构建模型参考自适应系统完成保护阻抗倾斜角在线调整减小过渡电阻影响；采用网络模型的结构和参数自校正方法进行保护整定值自适应校正；通过数字动模实例验证提出的新的保护对策和保护判据的有效性。研究成果预计可解决配电网消纳光伏发电的瓶颈问题，提高配电网安全稳定运行能力。

项目组针对光伏电站接入配电网（以下简称配网）故障产生的机理与对策展开研究。建立了具备LVRT的光伏电站接入配网的动态仿真模型，研究了不同工况下，光伏电站接入配网的故障特征与故障机理，根据光伏电站的出力情况，提出精确计算光伏电站提供短路电流大小的模型。为解决自动重合闸与LVRT（Low Voltage Ride Through，低电压穿越）之间的不匹配问题，提出了自动重合闸与LVRT以及保护的整定方法，为防止自动重合闸重合于永久性故障，提出了基于二次电弧和参数辨识的光伏电站接入配网故障识别判据，提高了光伏电站接入配网故障识别的成功率。为避免光伏电站接入配网，导致部分电流保护发生误动和拒动的问题，提出了基于小波变换的电流保护组合判据，新判据能很好地解决电流保护失去选择性的问题。为克服光伏电站波动性、间歇性给配网保护带来的影响，提出了基于光伏电站等值阻抗计算的电流自适应保护判据。为解决光伏电站集中接入电网，由于过渡电阻倾斜角导致距离保护不能正确动作的问题，提出了基于倾斜角自适应的距离保护判据。. 将上述所提出的保护方案以新疆某光伏电站接入配网为例进行了仿真验证，验证了的所提方法的有效性和正确性。