【作者】 白静；

【导师】 林莘；

【作者基本信息】 沈阳工业大学 ， 电机与电器， 2007， 硕士

【摘要】 电力变压器是电力系统中及其重要的电气设备，它的安全运行直接关系到电力系统的稳定。变压器长期在电网中运行会发生各种故障和事故，一旦遭到破坏，损失巨大。通过预防性试验和油中溶解气体的气相色谱分析结果判断变压器的绝缘状况，对防止事故的发生有很大作用，但定期的预防性试验可能出现过多的维修和不必要的停机，又不能及时发现故障；而变压器在线监测可以及早发现变压器故障，避免事故的发生，而且可以降低维护成本。变压器中最常发生故障的部位是绕组，它的损坏率约占整个变压器故障的60％～70％。诊断绕组变形的方法中，频率响应法、阻抗分析法、低压脉冲法虽然有可取之处，但是都属于离线方法，不能及时发现变压器的故障，不适于在线测量；通过实时计算变压器绕组短路电抗来在线诊断变压器故障是一种有效的在线监测方法。本文根据变压器绕组的短路电抗在正常运行时不发生变化，而在变压器内部故障时要发生变化的特性，应用辩识理论，利用变压器三相电压、电流的测量值来辨识绕组的短路电抗。把辨识结果对比正常时的三相绕组的短路电抗，可以发现绕组是否异常及故障发生的部位，保证变压器元件得到及时更换，防止变压器非正常退出运行。本文采用傅立叶算法来计算变压器三相电压、电流采样信号的基波分量的幅值与相角，实现变压器绕组的参数辨识，此时并没有考虑衰减直流分量。经过分析，当采样信号中存在衰减直流分量时傅立叶算法就会产生误差，而递推最小二乘法和卡尔曼滤波效果很好。最后本文介绍了变压器绕组参数辨识的实际应用与误差分析，分析了系统中软件、硬件方面的问题对测量短路电抗造成的影响；以及参数辨识的软件设计和运行试验，验证了方案的可行性。更多还原

【Abstract】 Electrical transformer is important and valuable electric equipment in electrical power system. It’s safely running related to electrical power system’s stabilization. Transformer will occur kinds of accidents when it operating in power line long time. If broken the loss is very high. Through preventive test and gas chromatograph to judge transformer insulation condition is helpful method to prevent accident. But periodic preventative test may have excess maintenance and unnecessary stop, also can’t find accident in time. But the on-line monitoring of winding deformation of transformer can forecast trouble in time, avoiding occur accident and reducing maintenance cost.Windings are the most fault components of transformer and its damage rate is about 60%～70% of all the transformer accidents. In the method of checking winding deformation, low voltage impulse method, frequency response analysis method and short-circuit reactance method, which can be used to measure and diagnose the deformation of power transformer winding are available in some extent, but they are all off-line monitoring. Accident can’t be fund in time and not fit on-line measurement. Through on-line measuring the short-circuit reactance of power transformer to estimate transformer winding deformation is an effective method.According to the character of short-circuit reactance of power transformer is not change when transformer is normal work and short-circuit reactance will change when transformer occur accident, using identification principle and basing on measuring primary, secondary currents and voltages to calculate the short-circuit reactance of windings. It is a cinder box system model. Normal work short-circuit reactance is reference and compare to calculation value, can judge whether the winding is normal and which winding happen accident. Make sure transformer components can replace in time, prevent transformer stop operation abnormally.Using Fourier algorithm to solve parameters of voltage and current, and then finish winding parameter identification. But no consider decaying DC component. Fourier algorithm for signals including decaying DC component may make error, but least squares algorithm and Kalman filtering algorithm have good effect.At last introduce transformer winding’s practical application of parameter identification and error analysis. Software and hardware may influence short-circuit reactance measurement. Introduce software design of parameter identification and put this software system in reality. Then verifying program is feasible.更多还原