基于预估的用户谐波评估方法

谐波源接入电网投产试验,根据小容量试验数据来预测满载时谐波发射水平有助于现场评价负荷电能质量问题,预控电网设备安全风险。该文提出了以负载容量为参数的变化谐波源通用预测模型及其求解步骤,并引入稳健回归算法对参数寻优以提高模型精度。在预测过程中,利用多个预测方法如线性模型、指数模型、乘幂模型构成预测模型群,对谐波电流数据进行拟合。该方法把建模对象当作黑箱,不考虑内部机理,可用于其他非线性负荷建模中。此外,通过对不同电网等值谐波阻抗参数辨识方法进行比较,提出统计回归方法有较好的准确度。最后,通过实例证明了该文提出的通用预测模型能较好地平衡拟合和外推,可以满足电能质量现场评估需求。

User Harmonic Evaluation Method Based on Prediction

The commissioning tests of harmonic loads in power grid and predication of harmonic emission level at full load in accordance with small capacity test data is helpful to evaluate power quality assessment at site and control risk of power grid equipment.In this paper,a novel methodology of establishing versatile harmonic model based on system identification technique and changeable load capacity is introduced,and a robust regression algorithm is introduced for parameter optimization and model accuracy improvement.During the predication,the predication group is composed by such multiple predication methods as linear model,exponential model and exponentiation model to fit data of harmonic current.The modeling object in this method is taken as a black box without considering the internal mechanism and such method can be used for modeling other non-linear loads.Moreover,the proposed statistical forecast model has better accuracy compared with other methods in terms of system harmonic impedance verification.Finally,examples are given to show that the proposed model provides good results on both fitting the known data in time sequence and the extrapolation of the data to be predicted and meeting the need of site assessment for power quality.