The assessment of the measurement error status of online Capacitor Voltage Transformers (CVT) within the power grid is of profound significance to the equitable trade of electric energy and the secure operation of the...The assessment of the measurement error status of online Capacitor Voltage Transformers (CVT) within the power grid is of profound significance to the equitable trade of electric energy and the secure operation of the power grid. This paper advances an online CVT error state evaluation method, anchored in the in-phase relationship and outlier detection. Initially, this method leverages the in-phase relationship to obviate the influence of primary side fluctuations in the grid on assessment accuracy. Subsequently, Principal Component Analysis (PCA) is employed to meticulously disentangle the error change information inherent in the CVT from the measured values and to compute statistics that delineate the error state. Finally, the Local Outlier Factor (LOF) is deployed to discern outliers in the statistics, with thresholds serving to appraise the CVT error state. Experimental results incontrovertibly demonstrate the efficacy of this method, showcasing its prowess in effecting online tracking of CVT error changes and conducting error state assessments. The discernible enhancements in reliability, accuracy, and sensitivity are manifest, with the assessment accuracy reaching an exemplary 0.01%.展开更多
在电容式电压互感器(capacitive voltage transformer,CVT)运行过程中,温度、受潮、电容芯子击穿等将导致CVT电容绝缘参量变化,从而改变电容分压器的分压比,引起CVT的计量误差。建立计及绝缘参数的CVT等效模型,研究多节CVT计量精度的影...在电容式电压互感器(capacitive voltage transformer,CVT)运行过程中,温度、受潮、电容芯子击穿等将导致CVT电容绝缘参量变化,从而改变电容分压器的分压比,引起CVT的计量误差。建立计及绝缘参数的CVT等效模型,研究多节CVT计量精度的影响规律。通过仿真分析,得到多节CVT计量误差随电容分压器等值电容和介损的变化规律,并搭建CVT计量误差试验平台,通过试验对理论分析和仿真结果进行验证。研究结果表明,多节CVT绝缘特性的变化将对其计量精度产生较大影响;电容变化主要影响CVT测量"比差",介损变化主要影响CVT测量"角差",当"低压臂电容"的等值电容增大0.22%时,比差变化-0.2%,介损增大0.20%时,角差变化4.8';电能计量误差会随CVT"高压臂电容"的等值电容和介损增加向"正方向"增加,随"低压臂电容"的等值电容和介损增加向"负方向"增加。展开更多
针对电容式电压互感器(capacitor voltage transformer,CVT)的谐波传递特性,综合考虑杂散电容等因素影响,建立等效电路模型,采用逐级计算各级等效阻抗和传递函数的方法,对CVT谐波传递特性进行深入计算和分析。基于Matlab/Simulink仿真...针对电容式电压互感器(capacitor voltage transformer,CVT)的谐波传递特性,综合考虑杂散电容等因素影响,建立等效电路模型,采用逐级计算各级等效阻抗和传递函数的方法,对CVT谐波传递特性进行深入计算和分析。基于Matlab/Simulink仿真工具对CVT谐波传递特性开展了仿真验证,并针对实际CVT开展了CVT谐波传递特性和测量误差的实际物理试验研究,试验结果与仿真分析结果具有较好的一致性。发现影响CVT谐波传递特性的因素不仅是LC串联谐振回路额定工作点的偏移,中间变压器一次侧和补偿电抗器的杂散电容对CVT谐波传递特性有着重要影响,传递函数幅频特性曲线呈现尖峰和低谷效应,导致较大的测量误差。展开更多
文摘The assessment of the measurement error status of online Capacitor Voltage Transformers (CVT) within the power grid is of profound significance to the equitable trade of electric energy and the secure operation of the power grid. This paper advances an online CVT error state evaluation method, anchored in the in-phase relationship and outlier detection. Initially, this method leverages the in-phase relationship to obviate the influence of primary side fluctuations in the grid on assessment accuracy. Subsequently, Principal Component Analysis (PCA) is employed to meticulously disentangle the error change information inherent in the CVT from the measured values and to compute statistics that delineate the error state. Finally, the Local Outlier Factor (LOF) is deployed to discern outliers in the statistics, with thresholds serving to appraise the CVT error state. Experimental results incontrovertibly demonstrate the efficacy of this method, showcasing its prowess in effecting online tracking of CVT error changes and conducting error state assessments. The discernible enhancements in reliability, accuracy, and sensitivity are manifest, with the assessment accuracy reaching an exemplary 0.01%.
文摘在电容式电压互感器(capacitive voltage transformer,CVT)运行过程中,温度、受潮、电容芯子击穿等将导致CVT电容绝缘参量变化,从而改变电容分压器的分压比,引起CVT的计量误差。建立计及绝缘参数的CVT等效模型,研究多节CVT计量精度的影响规律。通过仿真分析,得到多节CVT计量误差随电容分压器等值电容和介损的变化规律,并搭建CVT计量误差试验平台,通过试验对理论分析和仿真结果进行验证。研究结果表明,多节CVT绝缘特性的变化将对其计量精度产生较大影响;电容变化主要影响CVT测量"比差",介损变化主要影响CVT测量"角差",当"低压臂电容"的等值电容增大0.22%时,比差变化-0.2%,介损增大0.20%时,角差变化4.8';电能计量误差会随CVT"高压臂电容"的等值电容和介损增加向"正方向"增加,随"低压臂电容"的等值电容和介损增加向"负方向"增加。
文摘针对电容式电压互感器(capacitor voltage transformer,CVT)的谐波传递特性,综合考虑杂散电容等因素影响,建立等效电路模型,采用逐级计算各级等效阻抗和传递函数的方法,对CVT谐波传递特性进行深入计算和分析。基于Matlab/Simulink仿真工具对CVT谐波传递特性开展了仿真验证,并针对实际CVT开展了CVT谐波传递特性和测量误差的实际物理试验研究,试验结果与仿真分析结果具有较好的一致性。发现影响CVT谐波传递特性的因素不仅是LC串联谐振回路额定工作点的偏移,中间变压器一次侧和补偿电抗器的杂散电容对CVT谐波传递特性有着重要影响,传递函数幅频特性曲线呈现尖峰和低谷效应,导致较大的测量误差。
