单相三绕组换流变长时感应电压试验入口电容及负载特性的研究

Study on Entrance Capacitance and Load Characteristic of Long Term Induction Voltage Test of the Single-phase Three-winding Converter Transformer

长时感应电压试验(ACLD)是考核电气设备绝缘强度的重要技术手段,试验设计中换流变入口电容的计算极为关键。本文通过分析单相三绕组换流变压器变(简称"单相三绕组换流变")的结构对其进行电路和数学建模,通过该模型计算换流变各绕组之间及各绕组对地的等效电容,并利用各等效电容计算加压端的入口电容,进而得到合适的补偿电感量;利用现场试验数据对计算的入口电容量进行了验证,验证结果表明该模型的合理性。最后,本文根据多次现场长时感应电压试验加压经历,总结了该试验过程中换流变负载特性的变化规律。

Long term induction voltage test(ACLD) is the important method to check the insulation strength of converter transformer,and the calculation of its entrance capacitance plays a key role in the design of long term induction test.In this paper,the circuit and math model is established on the basis of analyzing the structure of the single-phase and three-winding converter transformer so to calculate the equivalent capacitance between windings or between the windings and the earthed parts.The entrance capacitance of the applied end is calculated by the use of each equivalent capacitance so to obtain appropriate amount of compensation inductance.The entrance amount of the calculated capacitance is verified by the test data at site so to verify the reasonableness of the model.Finally,the variation rule of load characteristic of converter transformer during the test period is summarized in accordance with the voltage application experience for the long term induction voltage test which is performed for many times at site.