铁磁谐振过电压是电力系统中的一种内部过电压，严重威胁着电力系统的安全稳定运行。经过长时间的研究，目前已得出了众多的消谐措施，但由于电网接线复杂，不同电网中的铁磁谐振性质也不同，消谐措施并不能通用。而且中性点直接接地系统铁磁谐振通常发生在高压侧，对电网的危害更大，根据以往的运行经验，中性点直接接地系统中最容易发生基波谐振，因此本文仅对中性点直接接地系统中的基波谐振进行研究。 本文对铁磁谐振产生的基本原理进行了分析，求取了基本谐振回路的约束方程。对铁磁谐振中的跳跃现象进行了阐述，确定了铁磁谐振发生需要满足的条件。分析中采用非线性电感的工频励磁特性，为准确分析基波谐振，对工频励磁特性的表达式进行了推导。在EMTP仿真模型中，电压互感器采用非线性电感并联线性电阻的模型，并利用EMTP的子程序SATURATION将实测的电压-电流特性转换成了电流-磁通特性。 在理论分析方面，根据得到的工频励磁特性，结合戴维南电源伏安特性对工频谐振判据进行了推导，得到临界阻尼电阻的表达式。然后就典型谐振变电站接线图分别在断开断路器和打开隔离刀闸两种情况下谐振的发生情况，以及在互感器二次侧星形绕组两端并联消谐电阻和退出消谐电阻两种情况进行了理论分析。并在EMTP中建立110kV典型谐振变电站的仿真模型，对以上理论分析逐一仿真，验证了理论分析的正确性。 经过理论分析和仿真验证，虽然消谐电阻消谐的方法可以有效的抑制谐振发生，但是，退出消谐电阻时依然可能产生谐振，所以结合阻容消谐的方法对消谐电阻消谐进行了改进，在并联消谐电阻的同时，经全桥整流电路并联一个大电解电容，不仅可以吸收谐振产生的能量，而且可以防止电容电压对系统产生影响。并用EMTP对打开断路器和退出消谐电阻时的情况进行了仿真，得到了良好的消谐效果。

Ferroresonance is an internal overvoltage in power system. It is a huge threat to the safety and operational stability of power system. Many useful measures to inhibit ferroresonance had been obtained after the long time research. But because of the complex of grid connection, the characters in different grids wouldn’t be the same. And the measure to eliminate ferroresonance cannot be used general. And the ferroresonance in neutral-grounded system usually happened at the high voltage side. It’s more harmful. According to the running experience, the fundamental ferroresonance in neutral-grounded system had happened most. So, this thesis only discussed the fundamental resonance to prevent and inhibit fundamental resonance. This thesis analyzed the basic theories of ferroresonance, and then induced the constraint equation of the circuit. Then introduced the characteristic of jump phenomena, confirmed the necessary conditions of ferroresonance. This thesis adopts power-frequency excitation characteristic of non-linear inductance to analyze fundamental resonance, and deduced the expression of power-frequency excitation characteristic. Take a non-linear inductance paralleling a linear resistance as the model of PT in EMTP. And then the U-I characteristic had been converted into i- characteristic with the program SATURATION in EMTP. In the area of theory study, according to power-frequency excitation characteristic, this thesis induced the criterion for fundamental ferroresonance, obtained equation of the critical damping resistance. Then it took the wiring diagram of the ferroresonance substation for example to analyses the two conditions that open the breaker and open the isolation breaker to judge whether the ferroresonance would happen, and then to analyses another two conditions that paralleling a small resistance on the Y windings of transform secondary side and cut down the resistance in theoretically. Next it built the simulation model of 110kV system by using EMTP for checking above analysis one by one. Through the Theory analyses and simulation checked, although it can inhibit ferroresonance effectively by using the method that paralleling small resistance. But when cut it down, ferroresonance would happen again. So, this thesis had improved the method by add a electrolytic capacitors after a full bridge rectifier circuit. It can absorb the power of resonance, and also can prevent the capacitor voltage to influence the system. Then two situations that open the break and cut off the resistance had been simulated by using EMTP.