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基于多模型融合的四端口VSC-HVDC混合线路故障识别与测距方法

A multi-model fusion fault identification and location method for four-terminal VSC-HVDC hybrid transmission lines

  • 摘要: 针对四端口VSC-HVDC架空线-电缆混合线路中分段参数差异、连接点折反射及过渡电阻变化导致故障识别与测距难度增大的问题,提出一种基于多模型融合的故障识别与测距方法。该方法仅利用L1首端正、负极电压和电流波形构造面向故障识别与测距的特征集合;在故障识别阶段,构建级联故障识别模型,实现故障线路识别及故障类型识别;在故障测距阶段,针对3类故障分别建立4类基础测距模型,并利用K-means算法划分波形特征区域,根据验证集区域误差确定动态融合权重,从而实现动态权重多模型融合测距。仿真结果表明,故障识别准确率在无噪声样本训练下为100%,噪声增强训练后在不同测试条件下均不低于98.67%;动态权重测距模型在无噪声样本训练条件下的平均绝对误差分别为0.18 km、0.15 km和0.19 km,均优于最佳单模型和多种全局固定权重融合方法;经噪声增强训练后,在信噪比为20 dB条件下3类故障平均绝对误差均不超过0.30 km;表明所提方法具有较高的故障识别准确率、测距精度和噪声鲁棒性。

     

    Abstract: To address the increased difficulty of fault identification and fault location in four-terminal VSC-HVDC hybrid overhead-line/cable transmission lines caused by section parameter differences, reflection and refraction at junctions, and variations in fault resistance, a multi-model fusion-based fault identification and location method is proposed. The proposed method constructs feature sets for fault identification and fault location using only the positive- and negative-pole voltage and current waveforms at the sending end of line L1. In the fault identification stage, a cascaded fault identification model is constructed to identify the faulted line and classify the fault type; in the fault location stage, four base fault location models are established separately for the three fault types, and K-means is employed to divide the waveform feature regions. Dynamic fusion weights are then determined according to the regional errors on the validation set, thereby realizing dynamic-weight multi-model fusion fault location. Simulation results show that the fault identification accuracy is 100% under noise-free sample training and remains no lower than 98.67% under different test conditions after noise-augmented training. Under noise-free sample training, the MAEs of the dynamic-weight fault location model are 0.18 km, 0.15 km, and 0.19 km, respectively, outperforming the best single model and several global fixed-weight fusion methods. After noise-augmented training, under a signal-to-noise ratio of 20 dB, the mean absolute errors of the three fault types are all no greater than 0.30 km, indicating that the proposed method achieves high fault identification accuracy, high fault location accuracy, and good noise robustness.

     

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